Patterns
and Perspectives
in Environmental
Science
NATIONAL SCIENCE BOARD 1972
/CO.
Patterns
and Perspectives
in Environmental
Science
Report Prepared for the
National Science Board
National Science Foundation
1972
**T<v
1930
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FOREWORD
This report has been prepared as a companion volume, a
supplement to the third annual report of the National Science Board,
Environmental Science — Challenge for the Seventies (NSB 71-1),
which was transmitted to the Congress by the President in June
1971. It contains much of the information and interpretation that
formed the basis for the conclusions and recommendations of the
annual report.
The present document makes no attempt to present a complete
view of environmental science or a coherent description of the natural
environment. These undertakings would be both impracticable and
overambitious within the confines of a single volume. Rather, this
volume is a compendium of the views and judgments of a large
number of scientific leaders, addressed to a broadly representative
array of topics that serve to illustrate, but not define, the scope and
nature of environmental science today.
The National Science Board is deeply grateful to these many
individuals for their thoughtful, candid, and sometimes controversial
opinions. In some cases the views expressed are in conflict with
others contained in the report itself or held by other members of the
scientific community. Hopefully these conflicting views will chal-
lenge scientists to resolve these differences and will point out that
there are, in fact, many areas in environmental science that demand
substantial investigation before any degree of adequate understand-
ing is achieved. It is these differences that contribute significantly
to the "patterns and perspectives" and help to identify directions of
needed scientific advance.
In accepting this report and recommending its publication, the
Board does not endorse all views contained herein, but hopes that
the report will prove informative to the general reader, that it will
provide useful insights to assist policymakers, whether in govern-
ment or in private institutions, and that it will contribute to the
discussions of scientists — students, teachers, and other professionals
— who are most intimately concerned with the status and future
progress of environmental science.
H. E. Carter
Chairman,
National Science Board
in
ACKNOWLEDGEMENTS
The National Science Board owes a debt of gratitude
to a large number of people for their assistance in the
preparation of this report. The Board expresses its appre-
ciation to all of them for a job well done.
Valuable aid was provided by the consultants who
gave freely of their opinions and served as a general
sounding board regarding the handling of the final format
of this report, as well as its companion volume, Environ-
mental Science: Challenge for the Seventies. This group
included: Dr. Julian R. Goldsmith (former member of the
National Science Board), University of Chicago; Dr. Louis
J. Battan, University of Arizona; Dr. John E. Cantlon,
Michigan State University; Dr. Wilbert M. Chapman
(deceased), Ralston Purina Company; Dr. Roger Revelle,
Harvard University; and Dr. Gilbert F. White, University
of Colorado.
The major responsibility for preparation of this re-
port was undertaken by the Staff of the National Science
Foundation, working in consultation with the Board and
the consultants. Dr. Lawton M. Hartman, III and Dr.
Eugene W. Bierly directed the effort. The result is
unique: a profile of a section of science that is rich in
information, broad in scope, and explicit as to the present
status of understanding. The National Science Board
expresses its sincere appreciation for the dedicated work
of these men.
The report has been edited by Mrs. Patricia W. Blair,
special editorial consultant to the Board. The Board
recognizes that her conscientious effort to present each
contribution in its best light has made the report much
more valuable.
The following staff members of the Foundation and
others have contributed in various ways, and the Board
acknowledges the time and effort that these people gave
from their already busy offices:
Dr. James R. Barcus, Program Director, Solar Terres-
trial Program
Dr. William E. Benson, Head, Earth Sciences Section
Dr. John L. Brooks, Program Director, General Ecol-
ogy Program
Mrs. Josephine K. Doherty, Program Manager, Re-
gional Environmental Systems Program
Dr. H. Frank Eden, Program Director, Meteorology
Program
Dr. John E. Geisler, Associate Program Director,
Meteorology Program
Dr. Walter H. Hodge, Head, Ecology and Systematic
Biology Section
Dr. Phillip L. Johnson, Division Director, Environ-
mental Systems and Resources
Mrs. Joan M. Jordan, Assistant Program Director,
General Ecology Program
Dr. Edward J. Kuenzler, Program Director, Biological
Oceanography Program
Dr. Lawrence H. Larson, Program Director, Physical
Oceanography Program
Miss Roberta J. Mears, Assistant Program Director,
Biological Oceanography Program
Dr. John M. Neuhold, Program Director, Ecosystem
Analysis Program
Dr. Richard I. Schoen, Program Director, Aeronomy
Program
Mr. Peter H. Wyckoff, Program Manager, Weather
Modification Program
and, from outside the Foundation,
Mrs. Eileen Cavanaugh, Smithsonian Center for Vio-
lent Phenomena
Dr. Charles Cooper, San Diego State University
Miss Margaret Deane, Bureau of Occupational
Health and Environmental Epidemiology, State of
California
Mrs. Barbara L. Kendall, National Center for At-
mospheric Research
Dr. Allen Kneese, Resources for the Future
Dr. William H. Matthews, Associate Director, Study
of Critical Environmental Problems, M.I.T.
The endless task of typing and filing of correspond-
ence was handled efficiently and effectively by Mrs. Judith
M. Curtis, NSF. Her accurate typing of material for this
volume as well as the first, particularly in situations where
time was at a premium, is much appreciated.
Special credit must be given to Mr. John C. Holmes, Finally, the Board acknowledges its great debt to
Head of the Printing and Reproduction Section, NSF. Mr. the approximately 150 scientists who responded to the
Holmes has made a difficult job much easier through his Board's request for information and analysis. Their frank
understanding of the problems and the positive approach and sometimes controversial papers are the basis for this
he took in solving them. report. It could not have been written without them. To
these busy scientists, who took precious time to furnish
There are others who have helped this report to come information, the National Science Board is extremely
into being who are not listed by name. To these people, grateful. It is these contributors who have made Patterns
the Board offers its thanks. and Perspectives in Environmental Science a reality.
vi
INTRODUCTION
A report on environmental science is at best
a risky undertaking. As was noted in the third
report of the National Science Board, Environ-
mental Science — Challenge for the Seventies
(NSF3 71-1):
Environmental Science is conceived ... as
the study of all of the systems of air, land,
water, energy, and life that surround man.
It includes all science directed to the system-
level of understanding of the environment,
drawing especially on such disciplines as
meteorology, geophysics, oceanography, and
ecology, and utilizing to the fullest the
knowledge and techniques developed in such
fields as physics, chemistry, biology, mathe-
matics, and engineering.
Indeed, the natural environment is so all-encom-
passing, so complex, that any attempt at exposi-
tion would appear doomed from the outset.
This report has a more limited, but per-
haps more crucial, purpose: to assemble, in
one place, enough material to permit the iden-
tification of fundamental patterns that might
help in appraising the status of environmental
science today. It seeks a basis for tentative
assessments of:
1. The availability of essential data and
successful theoretical formulations;
2. The present capability of environ-
mental science to predict future events; and,
hence,
3. The capacity of science to serve
society in its growing concern with the condi-
tion of the natural environment and what man
is doing to it.
To achieve this end, many leading environ-
mental scientists were asked by the National
Science Board to prepare informal statements on
specific, assigned topics covering a representative
sample of environmental phenomena. They were
asked to include their personal opinions and judg-
ments on the current status of scientific knowl-
edge and understanding. This volume comprises
a selection among the responses to those requests.
In order that the document not be mis-
understood, or be judged with reference to
inappropriate criteria, several important ca-
veats need to be stated.
First, no attempt has been made to provide
a complete description of the natural environ-
ment. Rather, the topics have been selected to
illustrate a fundamental feature of environmental
science — namely, that interactions prevail among
all environmental regimes.
Second, the report does not attempt a defini-
tive scientific review of environmental science.
Such a review, representing the consensus of
informed opinion, is probably not possible today
and, at the very least, could not be undertaken
without a massive team effort. Nor does the
report attempt to duplicate the many excellent
surveys that continue to be prepared on the status
of individual disciplines within the "environ-
mental sciences."
Third, this volume is not primarily concerned
with pollution, a subject of enormous environ-
mental concern but one that is receiving extensive
attention in many other places.
Fourth, in preparing this report for publica-
tion, it has not been feasible to update the original
papers. Thus, the material is now nearly two
years old. In most instances this does not affect
the conclusions presented, even though advances
in environmental science are being recorded at an
increasing rate.
Finally, it has been assumed, as a matter of
policy, that all the material included in this report
has a reasonable scientific basis, even though
some of the opinions expressed may cause con-
troversy among specialists, both contributors and
others. In certain instances, differences of opinion
will be observed in statements devoted to the
same topic. It is hoped that any resulting con-
troversy or disagreement will help to illustrate
the present status of environmental science and,
indeed, to generate constructive and extensive
discussion among scientists.
Specific attribution of papers and asso-
ciated illustrative material has been deliberately
avoided. The exigencies of the publishing sched-
ule have not permitted authors an opportunity to
review the edited product, and, where consistency
could be assured, material from two or more
papers have been combined; thus, while every
effort has been made to retain scientific accuracy
and individual style, authors should not be ex-
pected to bear individual responsibility for the
final version. Furthermore, in order to encourage
candid opinions, contributors were told from the
first that informality was sought and that indi-
vidual acknowledgments would not be made.
"Patterns and perspectives" in environ-
mental science begin to emerge from a reading
of the various papers in this report. Several ques-
tions recur. How adequate are the experimental
data that comprise an essential underpinning for
scientific progress? To what extent does a satis-
factory theoretical structure exist, as distinct from
a largely qualitative understanding? How mature
are attempts at mathematical modeling? How
adequate is the scientific basis for environmental
control? Has environmental science reached the
point where regulatory standards can be formu-
lated in terms of demonstrated benefits and
costs to society? What further scientific activity
is needed? What needs to be done?
The National Science Board, in its third re-
port, sought the broad outlines of the answers to
such questions at this point in time. Its findings
and recommendations comprise the first volume
of the third report, a summary of which is
appended. It is hoped that the publication of
these papers — the raw material, so to speak —
will help to generate further discussion of the
topics covered and their implications for environ-
mental science as a whole, its organization and
staffing, its choice of priorities, its methods of
investigation, and the extent of established infor-
mation and theory that can serve as the founda-
tion of future progress. In this case, as in so
many others, discussion and controversy are an
important prelude to action.
vm
CONTENTS
Page
FOREWORD iii
ACKNOWLEDGEMENTS v
INTRODUCTION vii
I THE SOLAR-TERRESTRIAL
ENVIRONMENT
Elements of the Solar-Terrestrial
System 3
Terrestrial Effects of Solar Activity . . 13
II DYNAMICS OF THE SOLID EARTH
1. Deep Earth Processes 21
An Overview of Deep-Earth
Chemistry and Physics 21
A Note on the Earth's Magnetic Field 23
2. Continental Structures and Processes
and Sea-floor Spreading 26
Continental Drift and Sea-floor
Spreading 26
Practical Implications of Major
Continental Processes 32
3. Earthquakes 35
Earthquake Prediction and Prevention 35
4. Volcanoes 40
Volcanoes and Man's Environment . . 40
Aspects of Volcanic Science 44
III CLIMATIC CHANGE
1. Cyclical Behavior of Climate 51
Long-term Temperature Cycles
and Their Significance 51
Fluctuations in Climate over Periods
of less than 200 Years 55
Environmental Cyclic Behavior: The
Evidence of Tree Rings and Pollen
Profiles 59
2. Causes of Climatic Change 62
Basic Factors in Climatic Change .... 62
The Radiation Balance 65
Climatic Change and the Effects of
Civilization 69
Environmental Change in Arid
America 73
IV DYNAMICS OF THE ATMOSPHERE-
OCEAN SYSTEM
1. Oceanic Circulation and Ocean-
Atmosphere Interactions 77
Oceanic Circulation and the Role
of the Atmosphere 77
On Predicting Ocean Circulation .... 79
Hydrodynamic Modeling of
Ocean Systems 81
Effects of Antarctic Water on
Oceanic Circulation 83
Tropical Air-Sea Rhythms 84
2. Atmospheric Circulation 89
Modeling the Global Atmospheric
Circulation 89
3. Weather Forecasting 93
Short-, Medium-, and Long-Term
Forecasting 93
Long-Range Weather Forecasting ... 97
Short-Term Forecasting, including
Forecasting for Low-Altitude
Aviation 101
4. Clear Air Turbulence 105
Clear Air Turbulence and
Atmospheric Processes 105
Prediction and Detection of
Wave-Induced Turbulence 107
A Note on Acoustic Monitoring 112
5. Urban Effects on Weather and Climate . . . 113
Urbanization and Weather 113
The Influence of Urban Growth on
Local and Mesoscale Weather 116
Urban Effects on Weather — the
Larger Scales 118
IX
Page
V SEVERE STORMS
1. Hurricanes 123
The Origin of Atlantic Hurricanes . . . 123
A report on Project STORMFURY:
Problems in the Modification of
Hurricanes 127
The Scientific Basis of Project
STORMFURY 130
A Note on the Importance of
Hurricanes 132
Geomorphological Effects of
Hurricanes 133
2. Tornadoes 137
Status of Tornado Research 137
Tornadoes — Their Forecasting
and Potential Modification 144
Tornado Forecasting and Warning . . 146
3. Hail 149
Hailstorm Research and Hail
Suppression 149
Current Status of Hail Prevention . . . 154
4. Lightning 157
Basic Processes of Lightning 157
Reduction of Lightning Damage
by Cloud Seeding 160
VI PRECIPITATION AND REGIONAL
WEATHER PHENOMENA
1. Drought 165
The Causes and Nature of Drought
and its Prediction 165
2. Precipitation Modification 169
Artificial Alteration of Natural
Precipitation 169
The Status of Precipitation
Management 172
3. Fog 180
Modification of Warm and Cold Fog . 180
Fog Dispersal Techniques 182
4. Tropical Weather 184
Monsoon Variations and Climate
and Weather Forecasting 184
Page
Tropical Meteorology, with Special
Reference to Equatorial Dry Zones. 187
5. Dust 191
African Dust and its Transport into
the Western Hemisphere 191
VII WATER RESOURCES, FORESTRY,
AND AGRICULTURE
1. Water Resources 197
Estimating Future Water Supply
and Usage 197
Water Movement and Storage in
Plants and Soils 200
A Note on Subsidence and the
Exhaustion of Water-Bearing and
Oil-Bearing Formations 203
2. Forestry 205
Water Quality in Forests 205
Factors Relating Forest Management
to Water Quality 212
3. Agriculture 215
Global Food Production Potentials . . . 215
The Hazard of Drought 218
VIII AQUATIC ECOSYSTEMS
1. Component Relationships 225
Trophic Dynamics, with Special
Reference to the Great Lakes 225
Effects of Artificial Disturbances on
the Marine Environment 230
Marine Flora and Fauna in the
Antarctic 231
Systems Approaches to Understanding
the Oceans and Marine Productivity 233
2. Oceanic Production 236
Primary Plant and Animal Life in the
World Ocean 236
The Southern Oceans in the
Production of Protein 240
Scientific Aspects of North Pacific
Fisheries 242
Some Scientific Problems Associated
with Aquatic Mammals 245
3. Estuaries and Coastal Zones 248
Page
The Relationship of Fisheries to
Estuaries, with Special Reference
to Puget Sound 248
Prospects for Aquaculture 250
4. Dynamics of Lakes 254
Lake Circulation Patterns 254
The Effects of Thermal Input on
Lake Michigan 257
5. Lake Eutrophication and Productivity .... 261
Fishery Deterioration in the Great
Lakes 261
Problems or Eutrophication in the
Great Lakes 267
Pollution and Recovery in Lake
Washington 270
IX TERRESTRIAL ECOSYSTEMS
1. Component Relationships 277
Environmental Design 277
Maintenance of the Biosphere, with
Special Reference to Arid Lands . . . 280
Energy Relationships in Ecological
Systems 285
A Note on Soil Studies 291
2. Forest Ecosystems 292
The Forest as an Ecosystem 292
A Note on Hubbard Brook 293
Tropical Forests 295
Comparison of Temperate and
Tropical Forests 298
3. Forest Animals 302
Problems of Animal Ecology in
Forested Areas 302
Wilderness as a Dynamic Ecosystem,
with Reference to Isle Royale
National Park 303
4. Forest Fire 306
Research into Fire Ecology 306
The Role of Fire in Forest
Management and Ecology 308
5. Polar Ecosystems 313
Polar Flora and Vegetation 313
X ENVIRONMENTAL CONTAMINANTS
Effects of Environmental Pollutants
and Exposures on Human Health
and Well Being 319
1. Airborne Chemicals 329
Chemical Contaminants in the
Atmosphere 329
Atmospheric Contaminants and
Development of Standards 332
Modeling the Atmosphere 335
Problems in the Ecology of Smog .... 337
2. Airborne Biological Materials 339
Atmospheric Dispersal of Biologically
Significant Materials 339
Biological Monitoring Techniques for
Measuring Aeroallergens 345
3. Pests and Pesticides 350
Environmental Pollution and Pesticides 350
Pesticides and the Pollution Problem . 354
4. Marine Contaminants 357
Effects on the Ocean of Atmospheric
Circulation of Gases and Particulate
Matter 357
Oil on the Sea Floor 361
5. Environmental Disease 364
Malaria 364
Other Parasitic Diseases 367
XI HUMAN ADAPTATION TO
ENVIRONMENTAL STRESS
Genetic Adaptation to the
Environment 373
Aspects of Man's Adaptation in the
Tropics 378
Adaptation to High Altitude 379
Adaptation to Smog and Carbon
Monoxide 385
APPENDIX: Summary and Recommendations .... 391
SELECTED REFERENCES 395
INDEX 401
CONTRIBUTORS 423
NATIONAL SCIENCE BOARD 426
XI
LIST OF ILLUSTRATIONS
Figure
Page
THE SOLAR-TERRESTRIAL ENVIRONMENT
1-1
1-2
1-3
1-4
1-5
II— 1
II-2
1 1-3
II-4
II— 5
1 1-6
II-7:
II-8:
III— 1 :
III-2:
1 1 1-3:
III-4:
Solar Flare 4
The Interplanetary Medium 6
The Magnetosphere 7
The Ionosphere 9
Atmospheric Temperature Distribution 12
DYNAMICS OF THE SOLID EARTH
Regions of the Earth's Interior 21
Chronology of Earth's Magnetic Field Reversals 24
Six Shifting Plates of the Earth 27
Continental Drift 33
Seismicity of the Earth 36
The Upper Mantle in the Region of
Fiji-Tonga-Raratonga 37
Seismic Risk in the United States 38
U.S. Volcanoes 45
III-
III-
III— 7:
III-8:
III-9:
111-10:
CLIMATIC CHANGE
Average Water Level in Lake Victoria
Changes in the Temperature of the
Ocean Surface
Temperature Curves Derived from Oxygen
Isotope Ratios of Deep-Sea Cores
Variations of the Mean Annual Temperature
of the Northern Hemisphere
Precipitation Patterns from Tree Rings
Computer Simulation of Sea-Level
Pressure Field
Factors in the Radiation Balance of the Earth
Observed Lagged Temperature Variation of
the Northern Hemisphere
Lagged Temperature Curve for the Northern
Hemisphere Corrected for COL.
Lagged Temperature Curve for the Northern
Hemisphere Corrected for COj and Dust . . .
51
53
54
56
eO
65
67
70
71
71
DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
I V-l : Sea-Surface Temperatures 77
IV-2: Classification of Waves and Currents 81
IV-3: Antarctic Waters and Their Circulation S3
I V-4 : Canton Island Data 85
IV-5: Walker's "Southern Oscillation" 86
IV-6 : SIRS Sounding 90
IV-7: Availability of Upper Air Data 92
IV-8: Data Required for Forecasts 94
IV-9: Forecasting Skill 99
IV-10: Waves and Turbulence in the Clear
Atmosphere 110
IV-11: Weather Changes Resulting from Urbanization 114
IV-12: Heat Island Effect 117
SEVERE STORMS
V-l : A History of Hurricane Seedlings 124
V-2: Hurricane Beulah, 1967 124
Figure Page
V-3: Probability Forecasts for Hurricanes 125
V-4 : Hurricane Losses by Years 127
V-5 : Hurricane Camille, 1969 134
V-6: Comparative Losses due to Severe Storms
and Hurricanes 137
V-7: Radar View of a Hooked Echo 139
V-8: Contour-mapped PPI Display 142
V-9: Contour-mapped Digital Display 143
V-10: Severe Weather Warning 147
V-ll : Structure of Hailstone Embryos 150
V-12: Hail Suppression at Kericho, Kenya 153
V-13: A Midwest Thunderstorm 155
V-14 : Lightning 157
V-15: The Initiation of a Lightning Stroke 159
PRECIPITATION AND REGIONAL WEATHER PHENOMENA
VI-1
VI-2
VI-3
VI-4
VI-5
VI-6
VI-7
VI-8
VI-9
VI-10
VI-11
VI-12:
VI-13 :
Annual Worldwide Precipitation 166
Precipitation Processes 169
Lattice Structures of Agl and Ice 173
Temperature Dependence of Nucleating Agents 174
Optimum Seeding Conditions 176
Simulated Effect of Cloud Seeding 177
Concentration of Ice Nuclei in a City 179
A Driving Hazard 180
Results of Fog-Seeding Programs 182
Monsoonal Areas 184
Array for Barbados Oceanographic and
Meteorological Experiment (BOMEX) 186
Frequency of Tropical Cyclones 189
Dust over the Tropical Atlantic 191
WATER RESOURCES
VII-1
FORESTRY, AND AGRICULTURE
Disposition of Water Diverted for Irrigation
Purpose 199
VII-2: The Hydrologic Cycle 201
VII— 3: Subsidence in Long Beach, California 203
VII-4: Ownership of U.S. Forest Lands 205
VII-5 : Effects of Forest Fires 208
VII-6: Relation of Sediment Particle-Size to Flow Rate 210
VII— 7: Effect of Land Use on Sediment Yield and
Channel Stability 211
VII-8: Potentially Arable Land in Relation to
World Population 215
VII-9: Transplanted Species 216
VII-10: Comparative Perceptions of Feasible
Adjustments to Drought 219
AQUATIC ECOSYSTEMS
VIII-1 : Trophic Levels 225
VIII— 2 : Effect of Alewives on Zooplankton 229
VIII— 3 : Sensitivity of Phytoplankton to Insecticides . . 234
VIII-4 : Some Phytoplankton 237
VIII-5 : Some Zooplankton 238
VIII-6: An Antarctic Food Chain 239
VIII-7: Distribution of the World's Fisheries 243
VIII-8: The Fate and Distribution of Marine Pollutants 245
VIII-9: A Purse Seine 246
xn
Figure Page
VIII— 10 : Cost of Economic Activities in
Corpus Christi Bay 249
VIII— 11 : Scheme for Using Sewage in Aquaculture .... 252
VIII-12: Upwelling of Coastal Lake Waters 256
VIII— 13 : Thermal Influence of Electric Power
Generation on Lake Michigan 258
VIII— 14 : Commercial Fish Catch — Lake Michigan .... 261
VIII-15: The Effect of Fertilizer on Nitrate
Concentrations in Rivers 265
VIII— 16 : Transparency Measurements in
Lake Washington 271
VIII— 17 : Measurements of Algae, Phosphorus, and
Nitrogen in Lake Washington 273
TERRESTRIAL ECOSYSTEMS
IX— 1: Serai Stages of a Deciduous Forest 277
IX-2: A Systems Model for a Grassland Ecosystem . . 279
IX-3 : Mosquito Submodel 282
IX-4: A Model Validation Study 284
IX-5: Major World Biomes 286
IX-6: Plant-Mouse- Weasel Chain 287
IX-7: Energy Budget of a Horse 288
IX-8: Relation Between Food Intake and Calorific
Equivalence of Invertebrates 290
IX-9: Ecological Effects of Deforestation 294
IX-10: The Effect of Tree Cover Removal in
the Tropics 297
IX— 11: Comparison of Temperate and Tropical
Forest Types 299
IX-12: Life Expectancy and Survivorship of
Isle Royale Moose 305
IX-13: Effect of Fire on Mesquite Shrubs 306
IX-14: Quantities of Nutrients Released by Burning
Tropical Vegetation 309
IX-15: A Section of the Tundra Biome 313
IX-16: Flow Diagram of a Wet Coastal Tundra
Ecosystem 315
ENVIRONMENTAL CONTAMINANTS
X-l : Composition of Clean, Dry Air 329
X-2: Pollution — An Environmental Problem 331
X-3 : Atmospheric Scales 332
X-4: A System for Discussing Air Pollution 333
X-5: Projection of Physical, Economic, and
Social Relationships 338
Figure
X-6: Atmospheric Particulate Matter Impc
in Aerobiology
X-7: Components of a Model for Pollen Aerol
X-8: Average Annual Losses from Crop Di
in the United States 342
X-9: Distribution of Ragweed Pollen in the
United States 346
X-10: Efficiency of Cylindrical Collectors
for Ragweed Pollen 348
X— 11: Resistance of Insects and Mites to Pesticides . . 350
X-12: Pesticide Usage and Agricultural Yields 351
X-13: Resurgence of California Red Scale 355
X-14: Concentration of DDT in a Lake Michigan
Food Chain 356
X-15: Comparison of Caucasian Dust Fall and
the Soviet Economy 359
X-16: PCB Residue in Fish, Birds, and Mammals .... 360
X— 17: Petroleum Hydrocarbon Contamination in the
Marine Environment 361
X-18: Changes in Malaria Morbidity Before and
After Mosquito Control 364
X-19: Areas of Major Malaria Potential 366
X-20: World Distribution of Schistosomiasis 368
X-21 : Ejection of Small Droplets into the Atmosphere
by Bursting Bubbles 370
HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
XI— 1: Distribution of the Yanomama Indians in
South America 375
XI— 2: Cytogenetic Findings in 49 Yanomama Indians
from Two Villages in Venezuela 375
XI-3: Frequency of Sickle-cell Gene in Liberia 377
XI— 4: Changes in Oxygen Consumption Capacity of
Lowlanders upon Upward Migration 380
XI-5: Oxygen Consumption Capacity Among
High-Altitude Natives 381
XI-6: Growth Rate Differences Between Nunoa
and U.S. Children 384
XI-7: Possible Epidemiological and Pathophysiological
Mechanisms Relating Carbon Monoxide and
Myocardial Infarction 386
XI-8: Rates of Chronic Bronchitis and Emphysema
for Smokers and Non-Smokers 387
XI-9: Hemodynamic and Respiratory Responses of
Five Normal Subjects to Carboxyhemoglobin
(COH,,) 389
Xlll
PART I
THE
SOLAR -TERRESTRIAL
ENVIRONMENT
ELEMENTS OF THE SOLAR-TERRESTRIAL SYS
The natural environment of man
consists of a single, gigantic system,
all of whose parts continuously in-
teract. It has been customary over
the centuries to view certain of these
parts in isolation: the atmosphere of
winds and moisture; the hydrosphere
of oceans, lakes, rivers, and ground-
water; the biosphere of living things;
and the lithosphere, or the crustal
portion of the "solid" earth. Only
during recent decades has a general
awareness been developing that the
behavior of each of these parts is
fundamentally influenced, and indeed
frequently controlled, by the behavior
of the others. Even less apparent to
many has been the role of the more
remote parts of our environment: (a)
the deeper reaches of the earth that
lie beneath the crust, and (b) the vast
region that extends from the upper
levels of the atmosphere to the sun —
and even beyond to the sources of
much of the cosmic radiation that
continues to bombard the earth. The
latter is designated here as the "solar-
terrestrial system" and forms the
starting point of this review of the
status of environmental science. The
system can be divided conveniently
into five parts:
The Sun — an undistinguished star,
but the principal source of the energy
that drives our environmental system.
The Interplanetary Medium — pre-
viously considered a vacuum, this
enormous region between the sun
and the near-earth environment is
now known to be filled with matter,
largely electrons and protons (hy-
drogen nuclei), originating in the
outer reaches of the solar atmosphere
(the "corona") and rushing outward
at great speeds as the "solar wind."
The Magnetosphere — that region
of space in which the earth's magnetic
field dominates charged-particle mo-
tion. An enormous storehouse of
solar energy, the magnetosphere is
bounded, on the sunward side, by
the "magnetopause," which is the in-
ner boundary of a transition region
(the "magnetosheath") beyond which
lies the solar wind. In the direction
away from the sun, the magneto-
sphere stretches beyond the orbit of
the moon in a long tail, like the tail
of a comet.
The lonospliere — a region con-
taining free electrically charged par-
ticles by means of which radio waves
are transmitted great distances around
the earth. Within the ionosphere are
several regions, each of which con-
tains one or more layers that vary
in height and ionization depending
on time of day, season, and the solar
cycle.
The Upper Atmosphere — an elec-
trically neutral region, whose chief
characteristics derive from the ab-
sorption of solar ultraviolet radiation.
The upper atmosphere (the "thermo-
sphere" and "mesosphere") overlaps
the lowest level of the ionosphere
but also extends below it. Near 50
kilometers from the earth, at the
"stratopause," the upper atmosphere
gives way to the atmosphere lay-
ers that immediately surround the
earth (the "stratosphere" and "tropo-
sphere").
This enormous volume of space is
matched by the great range of physi-
cal mechanisms that occur. In the
closer regions of the upper atmos-
phere, solar-terrestrial science is con-
cerned with many of the concepts
that meteorologists have evolved in
dealing with the weather systems of
the lower atmosphere; at the outer
extremes, the methods of astrophysics
and high-temperature plasma physics
must be utilized. The status of solar-
terrestrial science is thus strongly de-
pendent on the specific phenomena
being considered, for scientific prog-
ress has not been uniform across this
complex system.
At the same time, the solar-terres-
trial system, considered as a whole,
is both the source of beneficial radia-
tion, without which life itself could
never have developed on the earth,
and the mechanism for controlling
harmful radiation. Without this con-
trol mechanism, life could not long
survive. The whole range of solar-
terrestrial relationships is therefore
of the greatest environmental con-
cern.
The past twenty years have pro-
duced a wealth of detail and at least
partial understanding of the activity
going on in this region. The knowl-
edge has not produced quantitative
models of the dynamical effects on
the earth environment. The effects
are too complicated — in the same
way that weather is still too com-
plicated for satisfactory quantitative
modeling. But the knowledge informs
us about what is happening, allowing
us to understand the effects and to
avoid them in some cases, thus per-
mitting intelligent planning for the
future.
The Sun
A powerful source of energy, gen-
erated by thermonuclear processes,
the sun can nevertheless be expected
to remain in its present condition,
emitting radiation at a more or less
constant rate, for an extremely long
time. This surmise is based on astro-
nomical observations of stars similar
to the sun. Scientific attention is
therefore directed principally to as-
pects of solar activity, and its attend-
ant radiation, that are more variable
in time.
Most of the variability in solar
radiation is associated with (a) the
11-year solar-activity (or sunspot)
cycle, (b) the "active regions" that
are often displayed at the peak of
the cycle and are the source of intense
PART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
fluxes of extreme ultraviolet (EUV)
radiation, X-rays, and energetic par-
ticles (chiefly protons and electrons),
and (c) the "solar flares" that burst
forth from within these active re-
gions. (See Figure 1-1)
None of these three phenomena is
well understood and the outstanding
questions about the sun at present
are:
1. What is the basic reason for the
11-year solar-activity cycle?
2. What are the mechanisms un-
derlying the emission of the
more "exotic" portions of the
spectrum — i.e., X-rays and
Figure 1-1 — SOLAR FLARE
Solar flares usually lasting only a few minutes form very rapidly in disturbed re-
gions around sunspots. Flares occur quite frequently near the maximum of the solar
activity cycle and are related to catastrophic changes in the powerful magnetic fields
that are associated with sunspots.
EUV radiation at the short
wavelength end and radio
waves at the long end? Is
there anything that we should
know about such relatively un-
explored regions of the spec-
trum as the infrared and mil-
limeter-wave radiations?
3. What is the basic mechanism
responsible for solar flares?
The Eleven-Year Solar-Activity
Cycle — The basic mechanism that
produces this cycle is not known. It
is almost surely bound up with the
internal structure of the sun, which
will not be accessible to direct ob-
servation for the foreseeable future.
Thus, the answer to the first question
is not likely to be reached with any
degree of certainty for a considerable
time, although theoretical mechanisms
to explain solar activity should be
generated and tested as far as pos-
sible against observation. It remains
the most basic of all outstanding
questions of solar physics.
Active Regions — There is more
hope that a solution will ultimately
be found to the problem of growth
of individual active regions, as well
as the occurrence of flares within
these regions. It is known, for ex-
ample, that magnetic fields play an
important role in the associated en-
hanced ultraviolet and X-ray emis-
sions, in the growth of sunspots
(around which magnetic fields at-
tain strengths as great as 1,000
gauss), and in the sudden birth of
flares. Observations suggest that re-
gions of strong magnetic field are
carried outward by convection from
the interior of the sun. When these
magnetic fields break through the
visible surface, we see their effect
in the form of active regions and
sunspots. As the magnetic fields ex-
tend outward into the solar atmos-
phere, they encounter less and less
material. Flares originate at some
location within this outer solar at-
mosphere.
It is, thus, likely that answers to
the second question posed above will
ELEMENTS OF THE SOLAR-TLRK
come eventually from a gradual ex-
tension of present work, in the form
of refinement of satellite and space-
probe observations and the continua-
tion of the ground-based observations
that have provided the core of our
knowledge about the sun.
Solar Flares — Solar flares are
cataclysmic outbursts of radiation,
similar to those generally observed
from active regions, but in immensely
greater quantities and with much
higher energies. Fortunately, individ-
ual flares are short-lived (of the order
of an hour at most), and the most
intense ones are quite rare, even at
the peak of the solar cycle.
The effects of flares on the near-
earth environment make them by far
the most important solar phenom-
enon. The sudden surges of radiation
they produce constitute a major haz-
ard to manned space flights and a
hazard of uncertain magnitude to
the passengers and crew of super-
sonic-transport aircraft on transpolar
flights, where natural solar-radiation
shields are less effective than else-
where. Flares also increase the elec-
trical conductivity of the lower part
of the earth's ionosphere, giving rise
to severe interruptions of radio and
telegraph communications, particu-
larly at high latitudes.
Considerable progress in predict-
ing major solar flares has been made
through observations of time varia-
tions of the magnetic field configura-
tion within known active regions in
the lower solar atmosphere. While
improvements in empirical forecast-
ing techniques of this kind can be
expected, truly accurate predictions
must await an understanding of the
basic physical mechanisms respon-
sible for the development of a flare.
Many promising suggestions have
been put forward, but none has proved
entirely satisfactory. Some think a
flare is caused by the annihilation of
magnetic fields. Another interesting
possibility has emerged from satellite
probes of the "auroral substorms"
that occur in the earth's outer mag-
netosphere (see page 8). There is
an apparent analogy between many
of the observed radiation character-
istics of these substorms and those
of solar flares, opening up the pos-
sibility that their mechanisms are
basically similar, though with modifi-
cations appropriate to the different
solar environment.
Other Research Needs — Solar
EUV radiation is largely responsible
for the existence of the earth's iono-
sphere, and the broad nature of that
responsibility is now fairly clear.
Many of the details, however, re-
main beyond our grasp. The de-
tailed structure of the sun's radiation
spectrum in the EUV and X-ray
regions, the points of origin of these
radiations at the sun, and the mech-
anisms responsible for producing
them are still areas of considerable
uncertainty. Much progress is likely
to come from the satellite and space-
probe programs aimed at long-term
monitoring of solar radiation in these
wavelength regions with high an-
gular resolution.
The Interplanetary Medium
The broad features of the inter-
planetary medium are known and
understood. (See Figure 1-2) Inter-
planetary space is in fact tilled with
material, or plasma, from the outer
reaches of the solar atmosphere (the
"corona"). It is made up for the
most part of electrons and protons
(hydrogen nuclei), with small quan-
tities of helium and traces of heavier
nuclei. As a result of the instability
of the outer solar corona against
expansion, this material is rushing
outward from the sun at speeds of
the order of 400 kilometers per sec-
ond, forming the "solar wind."
Many important details are still
missing from this picture, however.
For example, solar-wind matter is
believed to constitute a sample of
the material that exists in the upper
solar corona. After a solar flare has
erupted, however, the nuclear com-
position of the solar wind has
seen to change quite suddenly to one
that contains up to 20 percent helium,
with appreciable amounts of heavier
elements. This material is probably
that of the lower solar atmosphere,
near the base of the corona or in the
chromosphere, where flares originate.
Spacecraft are providing an oppor-
tunity to study fairly directly these
interesting differences in the chemical
composition of different regions of
the sun itself. Comparison of solar-
wind compositions with the terres-
trial composition may produce in-
sights into how the earth and solar
system were formed.
"Collisionless" Shock Waves —
Another important area for study is
the reason for the fluid-like behavior
of the solar wind. In conventional
fluids, particles interact by collisions,
but collisions between individual
solar-wind particles are extremely
rare. Nevertheless, the solar wind
displays many of the properties of
a continuous fluid. In particular, the
wind's outward expansion is super-
sonic, in the sense that its speed
relative to the sun and planets is
greater than the speed with which
waves can propagate through the
medium. As it sweeps past any solid
body in the solar system, the wind
forms a standing shock wave up-
stream of the body, analogous to the
shock wave ahead of an aircraft in
supersonic flight. The width of the
wave that forms around the earth
is determined by the outward extent
of the earth's magnetic field, rather
than by that of the solid earth itself,
because the material in the solar
wind, being a good electrical conduc-
tor, is strongly affected by magnetic
fields. The earth's shock wave is
much larger than that formed around
other, more weakly magnetized bod-
ies like the moon, Venus, and Mars.
Collisionless shock waves are phe-
nomena that may have an important
bearing on our understanding of the
basic plasma physics that holds the
key to controlled thermonuclear fu-
sion. They have been difficult to
PART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
Figure 1-2 — THE INTERPLANETARY MEDIUM
In addition to visible radiation, both steady and sporadic electromagnetic emissions
from the sun extend over a large range of wavelengths (radio to X-ray). Low energy
charged particles in the expanding outer corona form the solar wind which, together
with the extended solar magnetic field, dominates the environment of the interplane-
tary medium. Occasionally, great flares in active regions emit charged particles of
cosmic ray energy.
produce under laboratory conditions,
and their properties even harder to
measure, because the probes used
have generally been larger than the
thickness of the shock wave itself.
Now, however, the shock wave on
the sunward side of the earth's mag-
netosphere provides a natural labora-
tory for studying collisionless shocks;
space-probe techniques, in which the
probe dimensions are much smaller
than the shock thickness, are likely to
produce a great deal of valuable
information.
The Interplanetary Magnetic
Field — The solar-wind material is
permeated by a weak magnetic field,
also of solar origin. This interplan-
etary magnetic field plays an impor-
tant role in guiding the highly
energetic flare particles toward or
away from the earth. The detailed
behavior of the field is exceedingly
complex, however, and not well un-
derstood. Furthermore, the picture is
complicated by the often irregular,
or "turbulent," structure of the mag-
netic field, which causes particles to
diffuse outward from the sun much
as chimney smoke diffuses in the tur-
bulent atmosphere. This turbulence
is highly variable and depends on the
general background of solar activity
at any particular time.
Since the effects of energetic par-
ticles reaching the vicinity of the
earth are generally undesirable, an
ability to predict their arrival would
be useful. One fact that helps in
their prediction is that, because the
sun rotates, interplanetary magnetic
field lines stretch out in a spiral,
much like water drops from a rotating
garden sprinkler. Hence, the earth is
connected magnetically to a point
well to the western side of the sun's
visible disc rather than to the center,
and intense flares originating in the
western portion of the disc are more
likely to produce serious effects than
those erupting in the eastern portion.
Nevertheless, a great deal more work,
both observational and experimental,
is needed to lay the foundation for
accurately predicting the arrival of
potentially harmful particles.
Blast Waves — Major solar flares
are accompanied by blast waves
which move out from the sun at
speeds of the order of 1,000 kilo-
meters a second, sweeping the am-
bient solar-wind plasma ahead of
them and bringing in their train a
greatly enhanced solar-wind flow.
The more intense blast waves are
not appreciably affected by inter-
planetary conditions. As the blast
waves encounter the earth, they pro-
duce major effects on the magneto-
sphere, giving rise to worldwide
magnetic storms and visible auroras
(often at much lower latitudes than
the conventional auroral zones). They
also provide the most important
sources of fresh material for the
radiation belts that surround the
earth.
Ability to predict these effects is
a matter of some practical impor-
tance, since serious interruptions in
radio communications and even in
domestic power supplies may result.
ELEMENTS OF THE SOLAR-TERRESTRIAL SYSTEM
Short-term prediction of blast waves
is not too difficult, since the appear-
ance of an intense flare on the sun
gives one or two days advance warn-
ing. Longer-term prediction is in-
volved with the problem, discussed
earlier, of long-term prediction of
flares themselves; this problem re-
mains unresolved due to our relative
lack of understanding of the basic
mechanisms underlying solar activity.
In general, the major practical re-
sult of increasing our knowledge of
the interplanetary medium would be
an improved ability to predict solar-
flare particle effects in the vicinity
of the earth. Basic advances in our
understanding of the processes gov-
erning collisionless plasmas, and of
the origin of the solar system itself,
are also likely consequences, and
should be pursued.
The Sunward Side — The mag-
netopause marks the true boundary
between the plasma originating at
the sun and that belonging to the
earth. On the sunward side of this
boundary lies the immense shock
wave described in the previous sec-
tion, which stands some 15 earth-
radii out from the center of the
earth, as well as a region about 5
earth-radii thick known as the "mag-
netosheath"; the latter is made up
of solar-wind plasma that has been
disoriented by passage through the
shock wave, together with tangled
irregular magnetic field.
The existence of something like
the magnetopause had been predicted
theoretically long before the Space
Age; its existence has now been
verified by satellites and space-
probes carrying magnetometers. But
many of its observed properties re-
main puzzling. Furthermore, most
of the observations have been con-
fined to near-equatorial regions, while
many of the important problems of
energy transfer from the solar wind
to the magnetosphere hinge on the
existence and properties of the mag-
netopause over the polar caps. Here
practically no information exists.
The Geomagnetic Tail — The con-
figuration of the outer magnetosphere
in the direction pointing away from
the sun is quite different from that
in the solar direction. Instead of
being compressed by the solar wind
into a volume sharply bounded by
the magnetopause, the magneto-
Figure 1-3 — THE MAGNETOSPHERE
The Magnetosphere
The magnetosphere (see Figure 1-3)
is the outer region of the earth's
ionized atmosphere, in which the
medium is sufficiently rarified that
collisions between charged and neu-
tral particles can be neglected and
the behavior of the charged particles
is dominated by the earth's magnetic
field. It can be regarded as the region
in which control of the environment
by the solar wind gives way to con-
trol by the earth. As such, it is an
enormous storehouse of solar energy,
extending out to a distance of some
10 earth-radii in the direction of the
sun and to a much greater distance,
perhaps as much as 1,000 earth-radii,
in the opposite direction.
The magnetosphere extends from
the "magnetopause," where the geo-
magnetic field terminates, down to
a height of about 250 kilometers
above the surface of the earth, and
thus includes a large part of the con-
ventional ionosphere. This section
will be devoted to the outer regions
of the magnetosphere proper; the
inner portion will be treated as part
of the ionosphere in the next section.
This conceptual model of the earth's magnetic field is based on years of spacecraft
observations. The dot marked "moon" indicates the relative distance at which the
moon's orbit intersects the plane containing the sun-earth line and geomagnetic axis.
PART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
sphere in the anti-solar direction is
stretched out by the action of the
solar wind into a long "tail," much
like the tail of a comet. The geo-
magnetic field lines are straight, with
the field itself directed away from
the earth (and the sun) in the south-
ern half and toward the earth in the
northern half.
The geomagnetic tail is now rec-
ognized to play a vitally important
intermediate role as a reservoir of
stored solar-wind energy. Its for-
mation requires some form of energy
transport across the boundary be-
tween the magnetosphere and the
solar wind, but whether this transport
is accomplished by a process analog-
ous to viscosity in a fluid, or by the
coupling together of geomagnetic and
interplanetary magnetic fields, or by
some more exotic process is not yet
known.
Equally mysterious are the pro-
cesses by which the tail releases en-
ergy. While some of the enormous
energy stored in the tail is continually
being drained into the earth's at-
mosphere, the most dramatic releases
are associated with relatively short
bursts, known as auroral substorms,
which can recur at intervals of a
few hours. They are accompanied
by disruptions of radio communica-
tions and surges on long power lines
that can result in power outages.
Associated increases in radiation-belt
particle fluxes shorten the lives of
communication satellites by degrad-
ing the performance of the solar cells
on which their power supply depends.
As noted earlier, the substorms are
thought to have many analogies to
solar flares. An understanding of
their mechanisms may thus lead to
an understanding of the flare mech-
anism. This understanding is vital
to our future ability to predict the
whole gamut of solar-terrestrial phe-
nomena that affect communications
and power supplies and may also
provide some insight into the plasma-
confinement mechanisms that are
needed to achieve controlled thermo-
nuclear fusion. Fortunately, the sub-
storm mechanism can be studied di-
rectly through satellite probes of the
tail region in which the release of
energy takes place.
Radiation Belts — The great en-
ergy released in the form of an
auroral substorm also serves to re-
plenish the radiation belts that sur-
round the earth with magnetically
trapped particles. The discovery of
these belts was the first dramatic
result of the Space Age in terms of
exploration of our near-space envi-
ronment. A broad mapping of their
structure and behavior has now been
obtained, although no complete ex-
planation yet exists of the sources
of the belts or of their dynamic
behavior. At first the belts were
thought to be fairly static and well-
behaved. Nature seemed to have pre-
sented us with an example of stably
confined high-temperature plasma.
It is now clear, however, that the
individual particles in the outer por-
tions of the belts are continuously
experiencing a variety of processes,
including convection in space, accel-
eration, and precipitation into the
atmosphere. Plasma instabilities of
some kind associated with the growth
of hydromagnetic and electromag-
netic waves in the magnetosphere
seem to be of major importance.
Similar instabilities have prevented
the confinement of high-temperature
plasmas in the laboratory.
The Plasma-pause — In addition to
confining the magnetosphere to a
sharply bounded cavity on the sun-
ward side, and stretching it out into
a long tail in the anti-solar direction,
the solar wind apparently generates
a vast system of convection that
affects the plasma throughout the
outer magnetosphere. This convec-
tion system pulls plasma from the
sunward side of the magnetosphere
over the top of the polar caps into
the tail, where a return flow carries
it back toward the earth, around the
sides, and back out to the front of the
magnetosphere.
Another of the great boundary
surfaces of the magnetosphere, known
as the "plasmapause," marks the di-
viding line between plasma that is
influenced by this convection and
plasma that is tightly bound to the
earth and corotates with it. The
plasmapause generally lies some 4
earth-radii out from the center of
the earth above the equator, and
follows the shape of the geomagnetic
field lines from there to meet the
ionosphere at about 60° magnetic
latitude. In common with other mag-
netospheric boundaries, such as the
magnetopause, it is extremely well
marked, and the properties of the
magnetospheric plasma change
abruptly in crossing it.
Although the close relationship be-
tween the plasmapause and the bound-
ary of the convection region has been
fairly well established, several fea-
tures of the plasmapause remain un-
explained. These include the sharp-
ness of the plasma changes on either
side, the shape of the plasmapause
at any given instant, and its radial
motions in time. There is some
evidence that inward movements
of the plasmapause during magnetic
storms have a bearing on the so-
called ionospheric storms, when the
density of the mid-latitude iono-
sphere drops sharply, leading to a
deterioration in radio communication.
Experiments aimed at probing the
plasmapause are presently being
planned with the aim of improving
our understanding of the mechanisms
influencing its formation and its dy-
namic behavior.
The Ionosphere
The ionosphere (see Figure 1-4) is
defined here as the electrically charged
component of the earth's upper at-
mosphere, consisting of free elec-
trons, heavy positively charged ions,
and a relatively small number of
heavy negatively charged ions. The
non-charged component — i.e., the
atmosphere itself — will be consid-
ered in the next section.
ELEMENTS OF THE SOLAR-TERR1
Figure 1-4 — THE IONOSPHERE
Geometric Altitude (in Kilometers)
DAYTIME
(max.)
10
OZONE LAYER
102 103 10"
Number of Electrons per cubic centimeter
The unfiltered ultraviolet and X-rays of the sun ionize many molecules, producing the
ionosphere. The ionosphere has several layers, each characterized by a more or less
regular maximum in electron density. The difference between the day and night
profile is due to the availability of solar radiation.
Our understanding of the forma-
tion and behavior of the ionosphere
is considerably more advanced than
in the areas discussed previously.
Major breakthroughs have been
made, particularly in the past two
decades, when direct probing through
rockets and satellites has been pos-
sible. Nevertheless, as is usually the
case, increasing knowledge has raised
new and previously unsuspected
questions, some of which have con-
siderable practical importance.
The ionosphere is conventionally
divided into three fairly distinct re-
gions:
1. The D region, lying between
about 60 and 95 kilometers al-
titude;
2. The E region, extending from
95 to about 140 kilometers; and
3. The F region, containing the
bulk of the ionization and ex-
tending upward from 140 kilo-
meters.
The E and F regions are capable of
reflecting medium- and short-wave
radio waves and thus permit long-
distance communication. The D re-
gion plays an important role in
propagating long waves, but it has
an undesirable effect on radio propa-
gation at the higher frequencies
through absorption of the radio-wave
energy.
The F Region — In the case of the
F region, where the concentrations
of free electrons reach their peak,
ionization is now known to be created
by EUV radiation from the sun. The
contributions of the various portions
of the solar spectrum within this
band are quite well understood. The
principal unknowns arise basically
from the fact that the atmosphere
at these altitudes is so rarified that
collisions between electrons, ions,
and neutral particles are extremely
rare, so that an individual electron
has a very long lifetime and can move
considerable distances from the re-
gion in which it is formed. As a
result, the electron concentration at
any given time and place is strongly
influenced by motions, including
winds, atmospheric waves, and dif-
fusion. Many of the anomalies in
the behavior of the F region, which
have been recognized since the early
days of radio propagation, are almost
certainly based on motions of this
kind.
Much of the current interest in the
F region is focused on the explanation
of these anomalies and the informa-
tion they can provide on the winds
of the outer atmosphere. One out-
standing anomaly is that the daytime
F region is usually denser in winter
than in summer, despite the decreased
sunlight available. Another is that
the F region tends to be maintained
throughout the long polar night when
the sun disappears completely for
long periods of time. This latter
phenomenon seems at least partly
due to bombardment of low-energy
particles from the outer magneto-
sphere, but movement of electrons
from lower latitudes probably also
plays a role.
The most powerful tool to emerge
in recent years for studying the F
region is the so-called incoherent
TART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
(Thomson) scatter radar technique,
which allows direct ground-based
investigation of high-lying ionization.
This has added immensely to our
knowledge of the mechanisms in-
fluencing the F region. It has been
possible to measure not only electron
concentration, but also temperatures
of the different plasma components
and effects of electric fields in causing
motion of the plasma. Results from
existing and planned scatter radar
installations will undoubtedly add a
great deal to our knowledge of this
outermost region of our atmosphere,
and will, hopefully, lead to improve-
ments in our ability to predict
changes in radio propagation condi-
tions.
Two F-region phenomena are of
special interest at this time. These
are the "polar wind" and the "iono-
spheric storm," both of which are
more than mere curiosities. The
polar wind, which has been predicted
on theoretical grounds but not yet
adequately verified observationally,
arises because of the existence of the
long geomagnetic tail described in
the previous section. The F-region
plasma can diffuse quite freely along
the direction of the earth's magnetic
field, and as long as the field lines
loop back into the opposite hemi-
sphere of the earth no plasma is
lost thereby. In the polar regions,
however, the field lines are greatly
stretched by the solar wind and
eventually become lost in interplan-
etary space. When F-region plasma
travels out along these field lines, it
ultimately disappears. This outward
flow is expected to be at least partly
supersonic; it plays a large part in
the loss of the lighter constituents
(hydrogen and helium) from the at-
mosphere.
Ionospheric storms, by contrast,
have been recognized observation-
ally for many years but still have
no adequate theoretical explanation.
Over most of the earth they appear
as a rather rapid decrease in the
electron concentration of the F region,
accompanied by a corresponding in-
ability to propagate radio signals that
normally propagate freely. Recovery
from this effect is much less rapid
than its onset. The ultimate explana-
tion for ionospheric storms may lie
in a combination of inward motion
of the plasmapause, discussed in the
last section, movement of the F region
caused by electric fields, and changes
in the photochemistry of the region.
The £ Region — As one moves
downward from the peak of the F re-
gion, photochemistry becomes stead-
ily more important relative to motions
in determining the characteristics of
the ionosphere. The E region, which
is largely formed by solar X-radiation
together with some EUV radiation,
shows quite different characteristics
from the F region, and many of these
differences arise from photochemical
causes. Movements of the ionization
are still important, however, in that
they give rise to very substantial
electric fields and currents because
of the difference between the colli-
sion characteristics of electrons and
ions. In fact, the whole situation is
analogous to a dynamo, in which an
electrical conductor moves in a fixed
magnetic field and thereby generates
an electric field. For this reason, the
region is often referred to as the
"dynamo region" of the ionosphere.
The E region is the seat of the
major current systems responsible for
surface magnetic-field variations. The
latter are particularly pronounced
near the magnetic equator, where the
magnetic field lines are horizontal,
and in auroral zones, where irregular
changes in ionospheric conductivity
are associated with particle bombard-
ment. The great concentrations of
ionospheric current in these regions
are known respectively as the "equa-
torial electrojet" and the "auroral
electrojet" by analogy with the jet
streams of the lower atmosphere.
While the broad reasons for the
existence of these electrojets are
fairly well understood, they still pre-
sent many puzzling features. The
growth of small but intense irreg-
ularities within and near the electro-
jets, in particular, presents a chal-
lenge in geophysical plasma physics
that has not yet been fully met.
The development of the thin, dense
layers of electrons known collectively
as "sporadic E," once an outstanding
problem, now appears to be largely
explicable in terms of the interaction
of vertical wind shears with metallic
ions of meteoric origin. This problem
is not completely solved, however,
and is still an active field for theory
and experiment. The continuous in-
flux of meteoric material to the at-
mosphere has turned out to be quite
important to both the E and D re-
gions of the ionosphere. There are
many unanswered questions con-
nected with this meteoric material,
including its chemical composition,
its distribution within the atmos-
phere, and its ultimate fate.
The D Region — After years of
relative neglect, a great deal of inter-
est is presently focused on the D
region, which is the real meeting
ground between the lower and upper
atmosphere. It now appears certain
that many of the strange facets of
this region's behavior are basically
due to meteorological effects con-
nected in as yet unknown ways with
the lower atmosphere. Thus, on cer-
tain winter days the D-region elec-
tron concentration rises abnormally;
this "winter anomaly" is associated
with sudden warmings of the strato-
sphere and mesosphere which are
probably connected with the break-
down of the polar winter vortex
of the general atmospheric circula-
tion. D-region electron concentra-
tions usually display a high degree
of variability during winter, while
they are relatively stable from day
to day in summer. These effects,
and others of a similar kind, are
currently arousing a great deal of
interest both among meteorologists,
who are extending their concepts
upward into this unexplored region
of the atmosphere, and among iono-
spheric workers, who are bringing
their interests downward.
10
ELEMENTS OF THE SOLAR-T: F
The practical importance of the
D region arises from the fact that it
efficiently absorbs radio waves at the
higher frequencies (MF and HF), and
reflects them at the lower frequencies
(LF and VLF). Both of these proper-
ties are greatly modified by solar dis-
turbances, since the energetic radia-
tion and particles emitted from the
sun at these times penetrate through
the thin upper regions of the iono-
sphere and deposit most of their
energy in the D region. When in-
tense solar flares give rise to fluxes
of energetic solar protons, for ex-
ample, the protons are funnelled by
the earth's magnetic field to the
polar regions, where they enter the
atmosphere and create very intense
ionization in the 50- to 100-kilometer
altitude range. The consequent strong
absorption of HF radio waves (known
as "polar cap absorption") com-
pletely disrupts short-wave radio
communication over the polar regions,
sometimes for days on end. The X-
rays emitted from the same flares
cause mild, brief fadeouts that extend
over the sunlit hemisphere of the
earth.
While the problem of predicting
these effects is ultimately the prob-
lem of predicting intense solar flares,
it is also important to learn as much
as possible about the relationship
between the detailed characteristics
of individual flares and the nature
and magnitude of the ionospheric
response. A great deal has already
been achieved in this area through a
combination of ground-based radio
observations and direct rocket and
satellite measurements of the radia-
tions and particles responsible.
Ionospheric Modification — One in-
teresting recent development is the
possibility of artificial modification of
the ionosphere. Research on this
problem is still in its infancy, but
success could lead to a major increase
in our ability to use the ionosphere
for radio-propagation purposes. Un-
controlled modification has been pro-
duced artificially by high-altitude
nuclear detonations; attempts are
now being made to modify the iono-
sphere in more sophisticated ways
by releasing ion clouds from rockets
and by use of high-power radars on
the ground. This approach is likely
to lead eventually to greater insight
into the mechanisms that control
the natural ionosphere as well as
provide us with a new range of pos-
sible practical uses.
The Upper Atmosphere
This section deals with the neutral
gas of the upper atmosphere, as dis-
tinct from the electrically charged
component that forms the iono-
sphere. In terms of altitude, the two
overlap; indeed, they are closely
coupled together in many ways, so
that several of the problems men-
tioned in the preceding section are
inseparable from the problems of
the neutral upper atmosphere. The
neutral upper atmosphere also shows
a range of properties not directly
related to the ionosphere, however,
and those are the questions of con-
cern here.
Like the ionosphere, the neutral
atmosphere has long been divided
into altitude regions, based mainly on
thermal structure. (See Figure 1-5)
The very lowest region of the atmos-
phere, in which the earth's weather
systems are located, is known as the
troposphere; here the temperature
generally decreases with increasing
altitude. Above the tropopause the
temperature first remains constant
and then increases with increasing
altitude through the stratosphere,
terminating at a temperature maxi-
mum near 50 kilometers altitude
known as the stratopause. Above
this lies the mesosphere, a region of
decreasing temperature with height,
which extends to about 85 kilometers.
The temperature at the mesopause is
lower than anywhere else in the at-
mosphere, and can be below — 150°
centigrade. Above the mesopause
lies the thermosphere, in which the
temperature steadily increases with
altitude, eventually reaching a fairly
steady value in excess of 1,000° cen-
tigrade. The warm regions of the
upper atmosphere owe their high
temperatures to the absorption of
solar ultraviolet radiation, by ozone
near the stratopause and by EUV
radiation in the thermosphere.
Tlic Thermosphere — The intense
heating experienced by the thermo-
sphere must set up some kind of
circulation pattern, analogous to the
circulation of the lower atmosphere
but differing in many important re-
spects because of the extreme rarity
of the medium and the influence of
the ionosphere. Little is known about
this circulation, but the effects of the
variable heat input on the density
of the thermosphere can be directly
detected through changes in the or-
bital period of satellites that travel
through the upper thermosphere. As
solar activity increases, the thermo-
sphere heats up, expands outward,
and increases the frictional drag on
satellites, thereby appreciably short-
ening their lifetimes.
Thermospheric heating depends on
the structure of the sun's EUV spec-
trum and its variability with solar
activity, neither of which is known
adequately, and on the constitution
of the upper atmosphere and the
manner in which the various atoms
and molecules absorb the radiation.
The non-uniformity of the heating
from equator to poles causes strong
temperature gradients which in turn
give rise to very strong winds. Some
of the properties of these thermo-
spheric winds have been inferred
from their influence on the F region
of the ionosphere, which is amenable
to exploration by ground-based ra-
dio sounding, but this information is
still very sparse.
The principal chemical components
of the thermosphere are atomic ox-
ygen, helium, and hydrogen; the two
latter, being the lightest constituents
of the atmosphere, tend to diffuse
toward the higher regions; atomic
hydrogen, in particular, is so light
that appreciable numbers of atoms
11
PART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
Figure 1-5 — ATMOSPHERIC TEMPERATURE DISTRIBUTION
KILOMETERS _^^^ APPROACHES
^^ TEMPERATURES
100 ► -^^^ EXCEEDING 1000° C.
THERMOSPHERE
PRESSURE
(Millibars)
THOUSANDS
OF FEET
90 ►
s
< 10-3
4 300
80 ►
Mccn
4 10-2
4 250
70 ►
^^^^ STANDARD TEMPERATURE
MESOS
PHERE ^*^^
<— 10-
60 ►
<200
50 ►
— STRATI
* l
4150
40 ►
STRATO
30 ►
SPHERE f
«-"
4100
20 ►
4 ioo
450
,„. --TROPOPAUSE -I
10 ► .
»=^
4 200
4 300
TROPOSPHERE "^^^^^
4 500
1 1
1 1 1 1 1 1 1 1****^ 1
4 700
4 1000
-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20
TEMPERATURE— CENTIGRADE
This chart shows the average distribution of temperature with height (lapse rate) of
the mid-latitude atmosphere. Lines ending with the word "pause" indicates the
boundary between two spheres. These boundaries are not always well established.
can attain escape velocity and leave
the earth entirely. The region in
which an atom can proceed outward
without colliding with other atoms is
known as the exosphere, the true
outer limit of the neutral atmosphere.
The exosphere's presence can be de-
tected from the ground because hy-
drogen scatters sunlight at night, but
its properties have been little ex-
plored.
The Mesosphere — This region,
which overlaps the D region of the
ionosphere, is the object of much
current interest. It is a region of
extreme complexity, in which mete-
orological phenomena, mixing, and
photochemistry all play a part. It
is made up mostly of molecular ni-
trogen and oxygen, just like the lower
atmosphere, but it contains many
minor constituents which, because of
their chemical reactivity or ready
ionizability, dominate the energies of
the region. Among these are ozone,
atomic oxygen, nitric oxide, water
vapor, and many others. The region
has proved extremely difficult to ex-
plore directly, since the atmosphere
is too dense to allow satellites to
remain long in orbit and too high
for the balloon techniques that are
used at lower altitudes. Most existing
information has come from rocket
soundings, but even here the prob-
lems are severe because of the com-
paratively high density and the fact
that rockets generally travel through
the region at supersonic speeds, cre-
ating shock waves that disturb con-
ditions locally.
The photochemistry of the region
has recently been under intensive
study, both through rocket experi-
ments and by way of laboratory
measurements of the rates of the
various key chemical reactions. A
broad picture of the important mech-
anisms is beginning to emerge, but
the roles played by transport and
movements in carrying constituents
from one point to another are still
largely unexplored. Of special im-
portance is the question of turbulence
in the mesosphere and its influence
on mixing of the various constituents.
Many of the problems of dispersing
pollutants in the lower atmosphere
arise from mechanisms similar to
those of distributing minor constitu-
ents in the mesosphere; many of the
photochemical reactions responsible
for smog formation are also the same.
Thus, the work presently being car-
12
TERRESTRIAL EFFECTS OF SOLA
ried out in the relatively less compli-
cated mesosphere may produce sig-
nificant insights into these practical
problems of the lower atmosphere.
Research Needs in the Upper At-
mosphere — The greatest single need
in this area of geophysics is for a
systematic exploration of the prop-
erties of the upper atmosphere using
rocket and satellite techniques. At
present we have only tantalizing
glimpses of many of the important
features, and little or no information
on how they change with time of
day, season, solar activity, and al-
titude. The techniques exist, and
all that is required is a sustained
synoptic program aimed at studying
a variety of upper-atmosphere param-
eters simultaneously under a wide
range of conditions. Such a program
would add immensely to our knowl-
edge of the upper reaches of the
atmosphere, and of the mechanisms
occurring there that may be important
to our existence. Because of the
complexity of the region, single prob-
lems cannot be handled in isolation,
and there is a real need for a thor-
ough exploration of the entire region.
Some scientists believe, however, that
we now have enough general knowl-
edge of what goes on in space that
future studies should be limited and
carefully aimed at specific goals.
TERRESTRIAL EFFECTS OF SOLAR ACTIVITY
The sun and the motions of the
of the earth about it essentially de-
termine the earth's climate. The time
of day and the season are associated
with well-known, normal variations
in the weather. Superimposed on
these regular patterns, however, are
extremely large deviations from cli-
matology. Some of these can be ex-
plained (and, hence, forecast with
some success) on the basis of physical
equations; some are so irregular or
little understood as to require a
statistical and probabilistic approach
to prediction.
Advances in Forecasting Technique
For many decades, atmospheric sci-
entists attempted to relate solar
perturbations to terrestrial weather
features, with no significant success.
Until recently, the only data avail-
able to them were those collected
from ground-based observatories and
weather stations. When radio arrived
on the scene, scientists began to re-
late variations in radio propagation
to observed changes in the character
of the sun.
The Space Age produced a revolu-
tion in understanding and procedure.
It became clear that, in general, the
farther one moves away from the
troposphere, the more one's environ-
ment is influenced by solar perturba-
tions. In the region above the meso-
pause, at about 80 kilometers from
the earth, variations in temperature
and density result almost entirely
from irregular solar emissions and
hardly at all from the moving pattern
of low-level cyclones and anticyclones.
These new insights — together with
the realization that men, equipment,
and their activities above the lower,
protective atmosphere are vulnerable
to (and may benefit from) environ-
mental changes — gave impetus to a
rush of new, very-high-altitude scien-
tific missions and related activities.
These include observations from rock-
ets, satellites, and improved ground-
based platforms; computerized data-
processing techniques; and prediction.
Solar Forecasting Services — At-
mospheric scientists, ionospheric and
solar physicists, and even astrono-
mers have shared in these new activi-
ties. But the atmospheric scientist, in
becoming involved with the expanded
environment, brings with him a spe-
cial point of view: he is vitally con-
cerned with data standardization, real-
time use and rapid transmission of
data, and the tailoring of his products
to operational needs. He brings added
emphasis with regard to synoptic cov-
erage. He uses meteorological tech-
niques in studying high-altitude vari-
ations such as anomalous variations
in neutral density. He even applies
Rossby's concepts to circulation fea-
tures on the "surface" of the sun.
A combination of the viewpoints
and methods of various kinds of sci-
entists has now brought a new and
important scientific service into being
— the solar forecast center. The first
such center was established by the
U.S. Air Force with a nucleus of
highly trained and cross-disciplined
scientists from the Air Weather Serv-
ice and the Air Force Cambridge Re-
search Laboratories; their mission was
to provide tailored, real-time support
to military operations affected by
the environment above the "classical
atmosphere." The ionospheric-pre-
diction activity of the National Oce-
anic and Atmospheric Administration
(NOAA) has been enlarged to pro-
vide a complementary service for the
civilian community.
Major Problem Areas
Solar forecasting centers and other
such forecasting services undertake
to meet the needs of a variety of cus-
tomers, including radio communica-
tors, astronauts, and scientific re-
searchers. The most important areas
of interest for such customers are as
follows:
Tlie Ionosphere — High frequency
(HF) (3-30 mHz) radio communica-
tions are widely used as an inexpen-
sive, fairly reliable means of trans-
mitting signals over long distances.
13
PART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
The HF radio communicator therefore
requires long-range and short-term
forecasts of the specific frequencies
that will effectively propagate
throughout the day. This is known
as frequency management and means,
in short, the determination of the
frequency that can be used from a
particular transmitter to a particular
receiver at a particular time. Propa-
gation of the HF signal to a distant
receiver employs single or multiple
"reflections" from the ionosphere and
the earth. Since the state of the iono-
sphere is dynamic and highly respon-
sive to solar activity, the number of
usable frequencies depends on (a) the
intensity of ionizing solar ultraviolet
and X-ray emissions and (b) the de-
gree of disturbance of the magneto-
spheric-ionospheric environment.
These are in addition to such factors
as time of day, latitude, and equip-
ment characteristics.
The HF communicator also requires
forecasts and real-time advisories of
short-wave fadeouts caused by X-ray
emissions related to solar flares. If he
gets these, he can insure that alternate
means of communication (satellite or
microwave methods) are available for
use in sending the highest-priority
messages. He can also differentiate
between communication outages
caused by propagation and those
caused by equipment malfunction. If
he knows that an outage is due to
a short-wave fadeout, the communi-
cator can simply wait for his circuit
to return to normal to continue
low-priority traffic rather than take
time-consuming action to switch fre-
quencies.
Other solar-terrestrial disturbances
which disrupt communications, such
as "polar cap absorption" events,
geomagnetic-ionospheric storms, and
auroral and geomagnetic substorm
events, must also be forecast to allow
the communicator to prepare to use
alternate means of communication.
Finally, the communicator needs an
accurate and complete history of ion-
ospheric disturbances to post-analyze
his system's performance. Outages
that have been attributed to poor
propagation when no disturbances
were observed can then be identified
as being due to mechanical or pro-
cedural problems.
High-Altitude Density — Space
vehicles which spend all or part of
their orbits in the region from 100 to
1,000 kilometers above ground are
subject to significant drag from the
neutral atmosphere. The density of
this region and the resulting satellite
drag are dynamic parameters. Their
variations reflect heating of the high
atmosphere produced by solar ultra-
violet variations and corpuscular pre-
cipitations, mostly at polar latitudes.
Satellite drag perturbs the orbital
parameters of the vehicles and, in
turn, complicates cataloguing, track-
ing, and control. Density variations
can sometimes alter the orbit enough
to carry the vehicle out of an area of
scientific interest or otherwise de-
grade its mission. If mission con-
trollers are to be able to compensate
adequately for orbital changes, they
need the following:
1. A dynamic, accurate model of
the global distribution of at-
mospheric density throughout
the region of interest;
2. Accurate observations of such
parameters of the model as
ultraviolet flux, solar-wind en-
ergy, and density; and
3. Accurate forecasts of these pa-
rameters.
Space Radiation — Man in space
faces radiation hazards from galactic
cosmic rays, trapped radiation, and
storms of particles (mostly protons)
from solar flares.
Cosmic radiation is so penetrating
that there is no practical means of
shielding against it. Astronauts sim-
ply must live with it. Its intensity is
low enough that it does not pose a
serious hazard.
The trapped-radiation environment
of near-earth space, however, is so in-
tense that prolonged exposure would
be fatal. Consequently, mission plan-
ners avoid that region by orbiting
below it or arranging to pass through
it quickly.
Solar-flare radiation poses a threat
for a lightly shielded astronaut. The
threat is not especially significant,
however, because (a) major events
occur rarely, (b) the astronaut can be
shielded effectively from most of the
radiation (in effect, the Apollo com-
mand module is a "storm cellar"),
and (c) the astronaut can return to
the safety of a shielded vehicle before
significant doses have time to build
up.
Despite the rather low critical na-
ture of this hazard, certain space-
environment support is essential to
protect man effectively from the haz-
ards of solar-flare radiation. Mission
planners need forecasts of the likeli-
hood of a particle event to insure that
they have enough options available
in case an event occurs. Observations
of the flare radiation are needed to
alert the astronauts. Techniques are
required to project the course and
intensity of an observed event so that
the radiation threat can be accurately
assessed.
Today there is some concern over
the radiation hazard to passengers
and crew of supersonic transports,
especially for polar flights. Though
not completely resolved, it appears
that the threat is minimal, since solar
cosmic-ray events sufficiently intense
to cause undesirably high radiation
doses are exceedingly rare and prob-
ably occur less than once every ten
years. But forecasts, observations,
and alerts will be needed to insure
full protection. Warning systems are
being developed, but warnings are
unlikely to reach aircraft already in
polar regions unless communication
14
TERRESTRIAL EFFECTS OF SOLAR ACTIVITY
satellites can be used that are not
subject to the "polar blackout" that
accompanies any biologically danger-
ous particle flux.
Electromagnetic radiation from so-
lar flares can be observed by sensitive
radio receivers in the form of radio
"noises," or interference, if the sun
happens to be in the direction that
the antenna is "looking." Observa-
tions of the sun's radio emission are
required to advise system operators
of the nature of the signal they are
observing.
General Observational Data — The
researcher needs forecasts and real-
time advisories of the occurrence of
selected solar and geophysical events
in order to schedule and conduct ex-
periments. He needs a consistent base
of comparable observational data that
can be vigorously examined for sig-
nificant relationships.
The State of the Art
To meet the needs of these various
operational and research communi-
ties, varied capabilities, skills, and
understanding are required. Individ-
ually or institutionally, the atmos-
pheric scientist and his colleagues
must provide the following:
1. Observations of the sun and
the space environment;
2. Rapid communications and data
processing;
3. Forecasts of significant solar
activity and geophysical re-
sponses.
In addition, they must have an un-
derstanding of the needs of specific
systems and operations, in order to
present advice to an operator in the
form that will benefit him most.
Observations of the Sun and the
Space Environment — The observa-
tions must be continuous, consistent,
comparable, and, where appropriate,
synoptic. They should include, but
not be limited to, solar flares, active-
region parameters, solar radio emis-
sion, space radiation, solar wind, the
ionosphere, and the geomagnetic field.
U.S. civilian and military agencies
maintain a network of operational
solar observatories around the globe.
This network is supplemented by nu-
merous scientific observatories.
Nearly continuous patrol of solar
chromospheric activity has been
achieved thereby. But the data ob-
tained are not as useful in operational
situations as, ideally, they might be.
First, they are subject to consider-
able inconsistency due to the subjec-
tive evaluations of the individual
observers. To obtain the final de-
scription of a solar event, many often
highly divergent observations are sta-
tistically combined. But in the quasi-
real-time frame of operational sup-
port, evaluation of a solar event must
be made on the basis of only one or
two observations.
Second, patrol of the sun's radio
emission is not complete. Gaps in
synoptic coverage exist, frequencies
useful for diagnosing solar activity
are not always available, and some ob-
servatories report uncalibrated data.
Operational radio patrol is about 90
percent effective, nonetheless.
Unmanned satellites are patrolling
energetic-particle emission and some
other space parameters for opera-
tional use. Real-time energetic-par-
ticle patrol presently exceeds 20 hours
a day; X-rays, 16 to 18 hours; and
solar wind, 8 to 9 hours. The obser-
vations are limited, however, in that:
(a) they are not continuous; (b) data
acquisition and processing are expen-
sive; (c) all needed parameters are
not sampled; (d) different sensors are
not intercomparable; (e) sensor re-
sponse changes; and (f) the vehicles
have limited lifetimes. Other scien-
tific satellites are sampling the space
environment, but limited readout and
data-processing capabilities and ex-
perimenters' proprietary rights pre-
vent these data from being used
operationally.
Observations of the ionosphere are
being made using vertical- and
oblique-incidence ionosondes, riome-
ters, and sudden-ionospheric-disturb-
ance sensors. For operational use,
however, timely receipt of data is
available from only about 20 loca-
tions around the world.
Several other observations of solar
and geophysical parameters are being
made for operational use. These in-
clude radio maps of the sun, ground-
based neutron monitors, and geomag-
netic-field observations. In general,
they suffer from the same limitations
as the observational networks de-
scribed earlier.
The recent establishment of World
Data Centers for storing and ex-
changing space data represents a sig-
nificant advance. These centers are
supported by the Inter-Union Com-
mission on Solar-Terrestrial Physics
of the International Council of Scien-
tific Unions. However, the primary
benefit comes to the research com-
munity rather than directly to the
operational community. Furthermore,
the program still suffers from incon-
sistencies, incomparabilities, and in-
completeness of much of the data.
Rapid Communications and Data
Processing — Rapid communication
and processing of data are essential
for timely forecasts. Even in the ab-
sence of forecast capability, they are
required to make maximum opera-
tional use of observations.
The Air Force has designated a
special teletype circuit for the rapid
movement and exchange of solar-
physical data within the United
States. Both civil and military agen-
cies have access to it. This circuit
makes possible near-real-time relay.
Data from the overseas observatories
must be relayed by more complex and
time-consuming means.
15
PART I — THE SOLAR-TERRESTRIAL ENVIRONMENT
Up to a year or two ago, processing
of the data was done by hand. Sys-
tems to process the data by machine
have now begun to come into use,
and the future will see more and more
use of computers in operational space-
environment support.
Forecasts of Significant Solar Ac-
tivity and Geophysical Responses ■ —
Geophysically significant solar events
must be forecast several hours, days,
weeks, or even years in advance. Sig-
nificant factors of the earth's environ-
ment, such as density at satellite alti-
tudes and the state of the ionosphere,
must also be forecast. In general, the
shorter the forecast period, the more
stringent the accuracy requirement.
Research on forecasting techniques
has been under way for many years.
The approaches have been many and
varied, and no single technique has
yet stood up under the test of con-
tinued operational use. Since knowl-
edge of the physics of solar processes
is lacking, present techniques are
based on statistical correlations and
relationships, observed solar features,
even the influence of planetary con-
figurations. By a combination of
many techniques and subjective skills,
operational forecasters have now de-
veloped a limited ability to forecast
solar activity.
How well can solar activity be fore-
cast? It is fairly safe to say that fore-
casting cannot be done well enough
for the operator to place full reliance
on it. Predictions can be used to ad-
vantage, but the operator knows he
must have alternatives available to
compensate for an incorrect forecast.
As a rough approximation (doubtless
open to challenge), no better than one
out of every two major, geophysically
significant solar events can be fore-
cast 24 hours in advance. Addition-
ally, at least three forecasts of events
that do not occur are issued for every
forecast that proves accurate. The
most valuable forecasting tool has
proved to be persistence. If a region
of solar activity hasn't produced a
major event, it probably won't. If a
major event has occurred, another is
likely to follow. Such factors as re-
gion size and radio-brightness tem-
perature, magnetic structures, and
flare history have also proved of some
value.
One factor that complicates the
forecast problem is that most research
schemes attempt to predict large "so-
lar flares." In reality, what the system
operator or mission controller is in-
terested in is the geophysically sig-
nificant solar event, whether large or
small. Experience has shown that
most large solar flares are geophysi-
cally significant, but some are not.
Most small flares are of no conse-
quence, but a disturbing percentage
are.
Forecasting of terrestrial proton
events after a flare has occurred has
been more successful, although it is
not without limitations due to uncer-
tainties and unavailability of relevant
data. The storm of particles emitted
by a flare takes a day or two to prop-
agate from the sun to the earth, and
this time interval permits a forecaster
to analyze the diagnostic information
contained in the electromagnetic
emissions that accompanied the solar
event. Analysis of radio-burst signa-
tures and X-ray enhancements indi-
cates whether the particles have been
accelerated. Quantitative forecasts of
the course and magnitude of the event
are often possible.
Other aspects of the space environ-
ment are being forecast with varying
degrees of success. The mean 10.7-
centimeter radio flux from the sun is
an input into high-altitude-density
models; efforts to forecast it have
been reasonably successful, in part
because the parameter varies rather
slowly. In contrast, practically no
capability exists for forecasting vari-
ability in the geomagnetic field, an-
other important input; short-term
prediction of geomagnetic storms is
particularly difficult.
Forecasts of ionospheric parameters
for radio communicators have been
made for many years. The field is
quite extensive and complex. The
Space Environment Laboratory, of
NOAA, issues monthly, and some-
times more frequent, outlooks on ra-
dio propagation conditions. Monthly
median predictions are generally ade-
quate for most frequency-manage-
ment applications, though significant
improvements could be made by more
frequent modification of the median
predictions. Ability to forecast iono-
spheric disturbances is closely tied to
the ability, discussed earlier, to fore-
cast geophysically significant solar
activity.
Understanding of Operational
Needs
Effective application of space en-
vironment observations and forecasts
requires, first, physical knowledge of
the interaction between the environ-
ment and the specific activity being
supported. Equally important, the
forecaster and the operator must de-
velop an effective rapport, based on a
thorough knowledge by the former of
the latter's system or mission. All
parties must recognize that many
things can happen to man's space-
related activities which are significant
but which cannot be explained.
The Direction of Future
Scientific Effort
There is a clear, continuing need to
advance the state of the art of opera-
tional solar and space-environmental
support. Capabilities are already far
from adequate, and the increasing
sophistication of the activities that are
affected requires a matching growth
in capabilities.
Future scientific efforts need to fo-
cus on the following:
1. Techniques to provide accurate
long-range and short-term fore-
casts of geophysically signifi-
16
TERRESTRIAL EFFECTS OF SOLAR ACTIVITY
cant solar events. Basic research
on the physics of events is re-
quired to get away from the
admitted limitations of statisti-
cal techniques.
2. Ionospheric forecasting and
specification techniques, espe-
cially in the area of short-term
frequency management. The
problem is especially acute dur-
ing magneto-ionospheric storms
and within polar latitudes.
3. Modeling of high-altitude at-
mospheric density that is dy-
namic— i.e., which reflects
hour-to-hour and day-to-day
variations.
4. Better and more complete ob-
servations of solar and geo-
physical phenomena and tech-
niques and hardware to process,
format, and transmit data with
minimal delay.
5. Operationally useful work on
the propagation conditions of
energetic particles between the
sun and the earth.
Techniques to forecast geomag-
netic disturbances accurately.
The level of disturbance of the
geomagnetic field must be re-
lated to operationally signifi-
cant applications such as the
ionosphere and high-altitude
neutral density.
Finally, the researcher should
not be satisfied with research
alone. He must push his ad-
vances into the realm of "de-
velopment" and their applica-
tion to the many activities of
mankind.
17
PART II
DYNAMICS OF
THE SOLID EARTH
1. DEEP EARTH PROCESSES
An Overview of Deep-Earth Chemistry and Physics
We recall that the earth consists of
three parts: a thin crust, five to forty
miles thick; a "mantle," below the
crust, extending a little less than half-
way down to the center; and a core.
(See Figure II-l) The crust is the
heterogeneous body on which we live
and grow our food, and from which
we derive all mineral resources, metals,
and fuels. It is the only part of the
earth that is accessible and directly
observable; the composition of the
mantle and core must be inferred from
observations on the surface.
The crust, the oceans, and the
atmosphere above them form the en-
vironment in which we live. This
environment has been shaped through
geologic time and continues to be
shaped by forces which originate in
the mantle beneath it. Its nature and
the processes that occur in it mold the
environment and determine what part
of the surface will be land and what
part sea, which oceans will expand
and which contract, which continents
will move apart and which come to-
gether. Forces mainly within the
mantle determine where mountains
will rise, where stresses will cause
rocks to fracture and flow, where
earthquakes will occur, how intense
and how frequent they will be.
(Earthquakes, it may be recalled,
have killed more than one million
people in this century.) Most vol-
canoes have their source in the
mantle. They destroy towns and
crops; the gases and solid particles
they discharge into the atmosphere
contribute significantly to atmospheric
"pollution," in the form, for instance,
of huge amounts of sulfur oxides; at
the same time, volcanoes provide the
very ingredients (water, carbon di-
oxide) without which life would be
impossible.
Figure 11-1— REGIONS OF THE EARTH'S INTERIOR
This idealized view of the interior of the earth shows the distance in kilometers from
the surface to the several regions. This view is admittedly simplified; as time goes
on, our knowledge of the structure of the earth's interior will undoubtedly become
more detailed and complex.
This interaction of crust and mantle
cannot be overemphasized. The whole
of the environment, the total ecology,
is essentially a product of mantle
activity.
Participation of the core in crustal
affairs is much less clear. At the
moment the core is of interest mainly
as the source of the earth's magnetic
field; but there are reasons to believe
that it may yet play a more funda-
mental role in the earth's economy,
perhaps as a source of gravitational
energy or perhaps in converting some
of the earth's kinetic energy of rota-
tion into heat.
Problems and Methodologies
Problems of the deep interior are
essentially (a) to determine the chemi-
cal composition and physical nature of
the materials composing the mantle
and core, which are nowhere acces-
sible to direct observation, and (b) to
determine the distribution and nature
of the energy sources and forces that
21
TART II— D\NAMICS Or THE SOLID EARTH
cause deformation, flow, and vol-
canism.
What observations, and what meth-
ods of study, do we have?
Seismic Waves — Seismic (elastic)
waves are propagated between the
focus of an earthquake and receivers
(seismographs) appropriately located
on the earth's surface. The speed of
propagation depends on the physical
properties of the propagating mate-
rial; this knowledge of speed versus
depth within the earth provides a clue
as to variations of physical proper-
ties — hence, of composition — with
depth. A serious problem arises in
that physical properties are sensitive
to pressure, and pressures inside the
earth greatly exceed those that can
conveniently be created in the labora-
tory for the purpose of studying their
effects on physical properties. High
pressures, of the order of those exist-
ing in the core, can be created by
means of explosive shock waves, but
precise measurement of physical prop-
erties under shock conditions remains
exceedingly difficult and costly.
Measurable Properties of the Eartli
as a Whole — Properties such as
earth's total mass, its moment of in-
ertia (best determined from observing
the motion of artificial satellites), and
the frequency of its free oscillations
(i.e., the "tone" at which the earth
vibrates, like a struck bell, when dis-
turbed by a sufficiently violent earth-
quake) provide constraints on density
distribution and physical properties in
the form of global averages. For in-
stance, the variation in physical prop-
erties with depth deduced from seis-
mic studies must average out to the
values deduced from these global con-
straints.
Lava — The nature of molten mate-
rial (lava) that rises from the mantle
and spills out on the surface (from
volcanoes) provides information on
the chemical nature of the source. The
problem is not straightforward, how-
ever, for the chemical composition of
the liquid that forms by partial melt-
ing of a system as complicated as
ordinary rock is not generally the
same as that of the parent rock; it
varies, moreover, as a function of
pressure and temperature. A great
deal of painstaking experimental work
at high pressure is required before the
chemistry of the earth's mantle will
be understood.
The "Heat Flow" — The heat that
escapes across the surface of the
earth from the interior provides in-
formation on the distribution of heat
sources and temperature within the
earth. (This heat flow, incidentally,
amounts to some 30 million mega-
watts and is equivalent to the output
of about 30,000 large modern power
plants.) The manner in which this
heat is transferred within the earth is
not precisely known; it is generally
believed that transfer in the deep in-
terior is mostly by "convection":
mass motion of hot stuff rising while
an equivalent amount of cold stuff
is sinking elsewhere. Convection is
generally believed to provide a mech-
anism to move the crust. Earthquakes
may well be the expression of strains
set up by this motion, and the geo-
graphic distribution of earthquakes
may reflect the present pattern of con-
vective flow in the mantle.
The chief problems are: (a) How
does the solid mantle flow? How do
we best describe its response to me-
chanical forces? (b) What flow pat-
tern do we expect in a body as com-
plicated and heterogeneous as the
earth? We are faced here with some
difficult mathematical problems in
fluid dynamics. It must also be re-
membered that, contrary to the com-
mon state of affairs in engineering
studies of fluid dynamics, where the
initial conditions are precisely stated
and controllable, conditions in the
earth regarding flow properties and
distribution of heat sources and tem-
perature are not known and must be
deduced from a comparison of theory
with geological or geophysical obser-
vations.
Sea-Floor Spreading — Geological
studies regarding past history of the
earth provide information as to what
has happened. Most importantly, they
provide information as to the rate at
which the crust deforms or moves, the
sense of its motion, and its duration.
This is essential input to the solution
of the dynamical problems mentioned
in the previous paragraph.
In this respect, the last decade has
seen what may well be the most im-
portant and far-reaching development
since the days of Hutton (1795).
What has now become known as
"sea-floor spreading" (or "plate tec-
tonics" or "global tectonics") is the
general proposition that new oceanic
crust is constantly generated from the
mantle along submarine ridges while
an equivalent amount of crust is re-
sorbed into the mantle at other places;
in between, the whole crust moves at
rates of a few inches per year. This
general pattern of motion provides an
important and much-needed clue to
the behavior of the mantle.
Phase Cliauges — It is well known
in materials science that, at high pres-
sure or temperature, substances may
occur under forms with properties
quite different from those of the same
substance under normal conditions
("phase changes"). A typical example
is that of common carbon that occurs
either as graphite (a soft material used
for lubrication) or diamond (the hard-
est known mineral). It is now clear
that phase changes do occur in the
mantle, the lower half of which has
properties quite different from those
of its upper half even though its gross
chemical composition may be roughly
the same. Again, a very large amount
of difficult experimentation on high
pressure is needed to ascertain the
form under which common minerals
could occur in the earth's deep in-
terior. It is not unlikely that such
studies could lead to the discovery
and synthesis of new materials of
engineering importance; for exam-
ple, very hard substances might be
produced.
DEEP EARTH PRC
Evaluation of Present Knowledge
In spite of recent advances, our
ideas and knowledge of the deep in-
terior remain largely qualitative. We
know roughly, but not exactly, what
the mantle consists of. We suspect
that phase changes occur at certain
depths, but we cannot pinpoint the
exact nature of these changes. We
can estimate roughly how much heat
is generated in the mantle and its
source (mostly radioactive disintegra-
tion), but cannot tell yet how the
sources of heat and temperature are
distributed. We do not have precise
information as to the mechanical and
flow properties of the mantle, and
haven't yet solved the mathematical
equations relevant to convection, even
though approximate solutions have
been found. We don't even know
whether the whole mantle, or only its
upper part, participates in the motion.
The situation regarding the core is
similarly vague. We know that it con-
sists dominantly of iron, but cannot
determine what other elements are
present. We know that the outer two-
thirds of the core is liquid, and that
motion in this metallic liquid gener-
ates the earth's magnetic field, but the
details of the process are still obscure,
and the full set of equations that
govern the process has not yet been
solved. Important physical properties
of the core, such as its electrical con-
ductivity, are still uncertain by one
or more powers of ten. The source of
the energy that drives the terrestrial
dynamo is still obscure. Even though
we suspect that motions in the core
are the cause of observable effects at
the surface (e.g., irregular changes in
the length of the day, small periodic
displacements of the earth with re-
spect to its rotation axis), we still can-
not assess these effects qualitatively.
We suspect interactions between the
core and mantle which ultimately af-
fect the crust, but cannot focus pre-
cisely on any of them.
Goals and Requirements for
Scientific Activity
To understand our total environ-
ment, to see how it came to be the
way it is, and how it is changing from
natural — as opposed to human —
causes, and to control it to our best
advantage (e.g., by curtailing earth-
quake damage or by muzzling dan-
gerous volcanoes with due regard to
their positive contributions to human
ecology), we need a better under-
standing of the constitution and be-
havior of the deeper parts of the
earth. To reach this understanding re-
quires a concerted and sustained ef-
fort in many directions, encompassing
a wide range of scientific disciplines,
from fluid mechanics to materials sci-
ence, from electromagnetic theory to
solid-state physics.
Observational Networks — If we
can foretell the future from the recent
past, it is clear that a key to further
progress is the establishment and
maintenance of a first-rate global net-
work of observatories such as the
worldwide network of standard seis-
mographic stations established under
the VELA program of the Department
of Defense. This network has enabled
seismologists to determine more pre-
cisely than ever before just where
earthquakes occur, and has brought
into sharp focus a remarkable corre-
lation between earthquakes and other
geological features that had only been
dimly perceived. This correlation is
fundamental to the notion of global
tectonics. Among other examples of
progress resulting from improvement
in instrumentation, one can mention
the determination of the depth in the
mantle at which some of the phase
changes occur and refinements in the
fine structure of the inner core.
Deep Drilling — Much speculation
could be avoided, and much informa-
tion gained, from analysis (of the type
to which lunar samples are subjected)
of samples from the mantle obtained
by deep drilling. Drilling through the
sedimentary cover of the ocean floor
has already been most rewarding in
its confirmation of the relative youth
and rate of motion of the oceanic
crust. But more is needed, and deeper
penetration through the crust into the
mantle at several points will eventu-
ally become necessary.
High-Pressure Experiments —
Finally, it would seem that a major
effort should be made to gain more
knowledge of the properties and be-
havior of materials subjected to pres-
sures of the order of those prevailing
in the deep interior (tens of millions
of pounds per square inch). Too much
is now left to guessing; solid-state
theory is presently inadequate and
would anyhow need experimental
confirmation.
A Note on the Earth's Magnetic Field
The earth's magnetic field was one
of the earliest subjects of scientific
inquiry. The field's obvious utility
in navigation, as well as the intrinsic
interest of the complex phenomena
displayed, have led people to study it
ever since the sixteenth century.
The study of the earth's field di-
vides into two parts: that of the main
part of the field, which changes only
slowly (over hundreds of years), and
that of the rapid variations (periods of
seconds to a year). The latter are
caused by things that happen in the
23
PART II— DYNAMICS OF THE SOLID EARTH
upper atmosphere and in the sun;
they are largely the concern of space
research. The former, the slowly
varying field, is the subject considered
here.
Interest in the slowly varying field
has been greatly increased by the
realization that it has frequently re-
versed in the past. (See Figure II-2)
The reversals have been helpful in
establishing the history of the oceans
and the movements of the continents.
The study of the magnetic field can be
expected to contribute — indeed, is
beginning to contribute — to the
search for oil and minerals. Measure-
ment of the magnetic field has be-
come one of the principal tools for
studying the earth.
The Origin of the Earth's
Magnetic Field
These applications lend a new in-
terest to the origin of the field itself.
A theory as to its origin has proved
hard to find. Only in our own day has
anything plausible been suggested.
Although a theory of the origin has
no discernible immediate practical
importance, it is a part of the story of
the earth without which we cannot
be said to understand what is going
on. Maybe we can get on very well
without understanding, but one feels
happier if important practical tech-
niques have a proper theoretical un-
derpinning.
The difficulty of discovering the
origin of the slowly varying field is
due largely to its lack of relation to
anything else. It is not related to
geology or geography and goes its
own way regardless of other phenom-
ena. In some places, some of the
changes are due to the magnetization
of rocks near the surface of the earth,
but this is not the case over most of
the field.
Fashionable theory holds that the
magnetic field is produced by a dy-
namo inside the earth. The earth has
a liquid core; the motions in this core
Figure 11-2— CHRONOLOGY OF EARTH'S MAGNETIC FIELD REVERSALS
YEARS AGO
690,000
890,000
950,000
,610,000
,630,000
1,640,000
1,790,000
1,950,000
1,980,000
2,110,000
2,130,000
YEARS AGO
2,430,000
2,800,000
2,900,000
2,940,000
3,060,000
4,380,000
4,500,000
LEGEND
Field as at Present
Field Reversed
This figure shows reversals in the polarity of the earth's magnetic field, a phenome-
non of global extent that is known to occur but has never been witnessed. These
data are derived from measurements of the direction (N-S) of magnetism frozen into
lava as it hardens. The effects of the reversals are unknown.
24
DEEP EARTH PROCESSES
are believed to cause it to act as a dy-
namo and to produce electric currents
and magnetic fields. The theory of the
process is one of the most difficult
branches of theoretical physics. Its
study is closely related to a wide
range of problems concerning the mo-
tions of liquids and gases in the
presence of magnetic fields, especially
to the problems of generating thermo-
nuclear energy.
But no realistic treatment of the
earth's dynamo has yet been given.
The subject does not require a
large-scale organized attack. It needs
thought and ideas that will come from
a few knowledgeable and clever peo-
ple. It is a subject for the academic,
theoretical physicists with time to
think deeply about difficult problems
and with access to large computing
facilities.
Perhaps the field's oddest feature is
that, as already noted, it occasionally
reverses direction (most recently, per-
haps, about 10,000 B.C.). Some scien-
tists have suggested that these rever-
sals have profound biological effects,
that whole species could become ex-
tinct, perhaps as a result of a large
dose of cosmic rays being let in as the
reversal takes place. There is some
observational evidence to support this
thesis. Other scientists do not believe
that this would happen, however, and
do not regard as conclusive the ob-
servational evidence for extinction of
species at the time of reversal. The
matter is clearly of some importance.
At various times in the past, the
majority of all forms of life are known
to have been rather suddenly ex-
tinguished, and this is a phenomenon
we would do well to understand. If
reversals of the magnetic field might
play a part in this drama, then we
have added reason for understanding
their cause and their effects.
25
2. CONTINENTAL STRUCTURES AND PROCESSES
AND SEA-FLOOR SPREADING
Continental Drift and Sea-Floor Spreading
The idea that continents move about
on the surface of the earth was ad-
vanced about a century ago and has
always had adherents outside of the
United States. In this country, where
no direct evidence existed, the concept
was first greeted with skepticism and
then, for fifty years, was viewed as
nonsense. All American thinking in
geology — economic or academic —
was built on the alternative concept of
a relatively stable earth.
This is now changed. The past few
years have seen a basic revolution in
the earth sciences. Continents move,
and the rates and directions can be
predicted in a manner that few would
have dreamed possible but a short
while ago. As a consequence, all as-
pects of American geology are being
reinterpreted, and in most cases they
are being understood for the first
time.
The continents are an agglomera-
tion of superposed, deformed, melted,
and remelted rocks with differing ages
covering a span of three billion years.
These rocks are eroded in some places
and covered with sediment in others.
The end result is a very complex con-
figuration of rocks with a history that
has not been deciphered in more than
a century of effort by land geologists.
The ocean basins are very different.
The rocks are all relatively young;
they are simply arranged and hardly
deformed at all; erosion and deposi-
tion are minimal. Consequently, it
was logical that their history would be
unraveled before that of the conti-
nents if only someone would study it.
Oceanographers have been engaged
in just such a study for about two
decades. It has been enormously ex-
pensive compared to continental ge-
ology — and trivially cheap compared
to lunar exploration. Thus, the haunt-
ing possibility exists that the same
effort on the continents might have
yielded the same results despite the
complexities. In the event, the break-
through was made at sea by the in-
vention of a whole new array of in-
struments and the development of a
system of marine geophysical ex-
ploration. The results have now been
synthesized with those from the land
to provide the data for the ongoing
revolution in the earth sciences.
Present understanding was achieved
in what in retrospect seems a curious
sequence. We depart from it to pre-
sent the new ideas in more orderly
fashion.
Continental Drift
First, a little geometry. The move-
ment of a rigid, curved plate over the
surface of a sphere can occur only as
a rotation around a point on the
sphere. This simple theorem, stated
by Euler, has been the guide for much
that follows. Earthquakes on the sur-
face of the earth are distributed in
long lines that form ellipses and cir-
cles around almost earthquake-free
central regions. If there are plates, it
is reasonable to assume that they cor-
respond to the central regions and
that the earthquakes are at the edges
where plates are interacting.
The motion of earthquakes confirms
the existence of plates with marvelous
persuasiveness. Euler's theorem speci-
fies the orientation of earthquake mo-
tion, and it has been confirmed for
many plates. Moreover, for any given
plate the earthquakes in front are
compressional as two plates come to-
gether; they are tensional in the rear,
where plates are moving apart. Along
the sides they are as expected when
one plate moves past another. (See
Figure II-3)
The knowledge that plates exist
and are moving has immediate im-
portance with regard to such matters
as earthquake prediction. For ex-
ample, one boundary between two
plates runs through much of Cali-
fornia along the San Andreas Fault.
We can measure the rate of offset in
some places and we now know that
related offsets must occur everywhere
else along the plate boundaries.
Earthquakes indicate that moving
plates exist now. But the evidence
that they existed in the past is of
a different sort. This comes from a
vast array of geological and geophysi-
cal observations — topographic, mag-
netic, gravity, heat flow, sediment
thickness, crustal structure, rock
types and ages, and so on. Integra-
tion of these observations indicates
that, where plates move apart, new
igneous rock rises from the interior
of the earth and solidifies in long
strips. These in turn split apart and
are consolidated into the trailing edges
of the two plates. Because the rising
rock is hot, it expands the trailing
edges of the plates. The expansion
elevates the sea floor into long central
ridges, of which the Mid-Atlantic
Ridge is but a part. As the new strip
of plate moves away, it cools and
gradually contracts. The cooling and
contraction cause the sea floor to sink.
This is why the ridges have gently
sloping sides that gradually descend
26
CONTINENTAL STRUCTURES AND PROCESSES AND SEA-FLOOR SPREADING
Figure 11-3— SIX SHIFTING PLATES OF THE EARTH
EURASIA
EURASIA
This diagram shows the six major "plates" of the earth. The double lines indicate
zones where spreading or extension is taking place. The single lines indicate zones
where the plates are converging or compression is taking place. Earthquake
activity is found wherever the plates come in contact.
into the deep basins. The basins are
merely former ridges.
Sea-Floor Spreading
The magnetic field of the earth re-
verses periodically, and a record of its
polarity is forever preserved in the
orientation of magnetic minerals in
volcanic rocks which cooled at any
particular time. This apparently unre-
lated fact gives us clues to the motion
of the plates. The new rocks at the
trailing edges of the plates record the
magnetic polarity like a tape recorder
and then, like a magnetic tape, they
move on and the next polarity change
is recorded. This occurs in each of the
plates moving away from their com-
mon boundary. As a result, the sea
floor in the Atlantic, for example, is
a bilaterally symmetrical tape record-
ing of the whole history of the earth's
magnetic field since the basin first
formed as a result of Africa and South
America splitting apart. We usually
read a tape recording by moving the
tape, but the stereo records of the
oceans are read by moving a ship or
airplane with the proper instruments
over the sea floor. From work on
land and at sea, the changes in mag-
netic polarity have been dated. We
can thus convert the magnetic records
into age-of-rock records and prepare
a geological map of the sea floor. In
the Atlantic, to continue with the pre-
vious example, the youngest rocks are
in the middle; they grow progres-
sively older toward the continents.
The remains of sea-surface micro-
organisms rain constantly onto the
sea floor to form layers of ooze and
clay. Where the crust is young, the
layers are thin; they thicken where
they have had more time to accumu-
late. The very youngest crust, which
has just cooled, is exposed as black,
glossy, fresh rock of the type seen
in lava flows in Iceland and Hawaii.
The outpouring of lava occurs at a
relatively constant rate but the plates
spread apart at different rates depend-
ing on the geometry. Consequently,
lava piles up into very long volcanic
ridges with a relief that varies with
the spreading rate. A slow spreading
rate produces mountainous ridges;
fast spreading produces low, gently
sloping, but very long hills.
27
PART II— DYNAMICS OF THE SOLID EARTH
Most of the remaining topography
of the sea floor is in the form of
roughly circular volcanoes which can
grow as large as the island of Hawaii.
These volcanoes remain active for
tens of millions of years and during
that time they drift as much as a
thousand miles. If they develop on
young crust, they necessarily sink
with the crust as it cools. This seems
to be the explanation for the drowned
ancient islands commonly found in
the western Pacific. Once they were
islands, but now they are as much as
a mile deep.
The phenomena that occur where
two plates come together are natu-
rally different from those that occur
where they spread apart. If the plates
come together at rates of less than a
few inches per year they seem to
crumble and deform into young moun-
tain ranges. Where they come to-
gether faster, the deformation cannot
be accommodated by crumbling. In-
stead, the plates overlap and one of
them plunges deep into the interior
where it is reheated and absorbed.
This produces the most intense de-
formations on the surface of the
earth. A line of fire of active vol-
canoes, deep depressions of oceanic
trenches, and swarms of earthquakes
mark the line of junction. Ancient
rocks of the continents are now being
reinterpreted as having once been
deep-sea and marginal-sea sediments
that were deposited where plates
came together. They occur in central
California, the Alps, and many other
mountain ranges. Typically, they are
highly deformed, which seems quite
reasonable considering what must
happen when plates smash together.
Implications of the
New Knowledge
Since the sea floors are young, con-
tinental rocks contain what records
may exist of ancient plate motions.
The present revolution in understand-
ing was needed to serve as a guide to
geological exploration, however. Land
geologists had long noted similarities
between the rocks on opposite sides
of the South Atlantic. In the past few
years, many more confirming correla-
tions have been discovered. Knowing
that the continents were once joined,
we can reconstruct, in the mind's eye,
a history in which they were once but
a small distance apart and the nascent
Atlantic was a narrow trough.
We should pause for a moment to
consider how important to economic
resource development the new ideas
may be. The continental shelves of
Atlantic coastal Africa and South
America, for example, contain salt de-
posits and sediments in thick wedges
that seem to lack any dam to trap
them. These deposits contain oil. We
can imagine the difficulties American
oil geologists had in interpreting their
records and predicting where to drill
when they had no idea of how the
oil-bearing rocks accumulated. How
easy it may now become, when their
origin can be readily explained as
occurring in the long narrow trough
of the newborn Atlantic!
Until now exploration has been
adequate to demonstrate the existence
of continental drifting and global de-
formation, but much remains to be
done to flesh out the reconstruction of
the history. If the exploration at sea
continues and is matched by compa-
rable effort at continental margins
and on land, we may hope to see the
beginning of a deep new understand-
ing of the earth.
Continental Structures and
Processes
Our knowledge of continental
crustal processes, except in the vicinity
of the continental margins, has lagged
behind our knowledge of oceanic
crustal processes. One reason for the
great progress in the study of oceanic
crustal processes is the beautifully
simple pattern of magnetic anomalies,
magnetic-field reversals, and earth-
quake and volcanic activity in the
vicinity of the continental margins
that led to the discovery of sea-floor
spreading. But another reason must
be that the earth scientists who made
these advances were not inhibited by
the traditions and prejudices of scores
of years of separation into highly
compartmentalized sub-disciplines. Of
course, the continental crust is com-
plex, and simple patterns, if they
exist, are obscured by the geological
and geophysical scars of billions of
years of continental damage and re-
building. But the attitudes and study
methods that led to the discovery of
sea-floor spreading and downward-
plunging plates will be needed if we
are to improve our knowledge and
understanding of continental proc-
esses during the 1970's.
Structure of the Continental Crust
The average thickness of the con-
tinental crust of the United States, as
determined by seismic measurements,
is 41 kilometers; its volume is about
40,000 x 104 km3. The average
crustal thickness in the west of the
Rocky Mountains is 34 kilometers,
while the average thickness to the
east of the mountains is 44 kilometers.
The volume of the western crust is
only about 10,000 x 104 km:i. Thus,
the western crust accounts for only
one-fourth of the continental total by
volume, as compared to 30,000 x 104
km3 for the eastern crust, although its
surface area is almost a third of the
total. Average seismic velocities also
suggest that the western crust is less
dense than the eastern crust. Thus,
the western crust — the portion of the
crust in which continental dynamic
processes (earthquakes, volcanic erup-
tions, magmatism, ore deposition, and
mountain-building) have been active
during the past 100 million years or
so — is the lesser fraction of the con-
tinent in terms of volume and mass.
Further Western-Crust Data — A
recent reinterpretation of a network
of 64 seismic-refraction profiles re-
28
CONTINENTAL STRUCTURES AND PROCESSES AND SEA-FLOOR S
corded by the U.S. Geological Survey
in California, Nevada, Idaho, Wyo-
ming, Utah, and Arizona from 1961
to 1963 indicates that crustal thick-
ness reaches maxima under the Sierra
Nevada Range (42 km.), the Trans-
verse Ranges of southern California
(37 km.), and in southwestern Nevada
(36 km.). The crust is relatively thin
under the Coast Ranges of California
(24 to 26 km.), the Mojave Desert
(28 km.), and parts of the central
Basin and Range Province in Nevada
and Utah (29 to 30 km.). The base
of the crust dips generally from the
Basin and Range Province toward
greater depths in the Colorado Plateau
(43 km.), the middle Rocky Mountains
(45 km.), and the Snake River Plain
(44 km.). A velocity boundary zone
between the upper and lower crust
can be well determined only beneath
the middle Rocky Mountains, the
Snake River Plain, and the northern
part of the Basin and Range Province.
The average velocity of the western
crust is low, typically about 6.1 to 6.2
kilometers per second, but signifi-
cantly higher in the Colorado Plateau
(6.2 to 6.5 km/sec), and the Snake
River Plain (6.4 km/sec). Upper-
mantle velocity is less than 8.0 kilo-
meters per second under the Basin and
Range Province, the Sierra Nevada,
and the Colorado Plateau and equal
to or greater than 8.0 kilometers per
second under the Coast Ranges of
California, the Mojave Desert, and
the middle Rocky Mountains.
Recent refraction work indicates
that the average crustal velocity in the
Columbia Plateau is high, as expected,
but that the crust is about 10 to 15
kilometers thinner than it is in adja-
cent areas. Thus, the Columbia Pla-
teau has seismic properties similar to
those of a somewhat overthickened
oceanic crust. So does the Diablo
Range of California. The Franciscan
formation (a metamorphosed struc-
ture) exposed in the Diablo Range,
believed by many geologists to have
been deposited in a Mesozoic oceanic
trench, apparently extends to a depth
of 10 to 15 kilometers; it was de-
posited directly on a basaltic crust
that now extends to a total depth of
about 25 kilometers.
Composition of the
Continental Crust
In a rock of a given composition,
both metamorphic degree and water
content affect seismic velocities at
various pressures and temperatures.
Recent laboratory research in the
United States suggests that pressures
and temperatures at most crustal
depths would place the rocks within
the stability field of eclogite rather
than basalt. Seismic velocities in the
lower crust formerly interpreted as
appropriate for basalt are therefore
regarded by many petrologists as
more appropriate for more silicic rock.
However, the presence of significant
amounts of water in the lower crust
would produce abundant hydrous
minerals in a rock of basaltic com-
position; this would result in seismic
velocities similar to those in the lower
crust.
Given such uncertainties, it seems
that the only positive assertion that
can be made about the average com-
position of the continental crust is
that it is intermediate and probably
not too different from monzonite. The
lower crust may be basaltic, interme-
diate, or even silicic, and the most re-
liable guide to its composition is
probably geologic association. For ex-
ample, in the Snake River Plain, where
basalt is exposed at the surface, it
seems reasonable to interpret the high
velocities of the lower crust as indica-
tive of basalt. In other areas, the
higher velocities should probably be
regarded as indicative of intermediate
rock.
Structure and Composition of the
Upper Mantle
Seismic probing of the upper man-
tle has established the existence of
two important velocity transition
zones: one at a depth of about 400
kilometers, in which magnesium-rich
olivine is transformed with increasing
pressure to spinel; and another at a
depth of about 650 kilometers, in
which spinel is presumed to be trans-
formed to compact oxide structures
with increasing pressure. Recent esti-
mates of the density of the uppermost
mantle, based on statistical models
using all available evidence, yield
densities of 3.5 to 3.6 grams per cm3,
significantly higher than the densities
deduced from the usual velocity-
density relations. Rocks of this den-
sity and the seismic velocities ob-
served just below the Mohorovicic
discontinuity could be either eclogite
or iron-rich peridotite. Given the
lateral heterogeneity of the upper
mantle indicated by the variable seis-
mic velocities, it seems most reason-
able to regard the upper mantle as
grossly heterogeneous, consisting pri-
marily of peridotite but with large
lenses, or blocks, of basaltic, eclogitic,
intermediate, and perhaps even silicic
material distributed throughout.
There is much seismic evidence that
a low-velocity zone for both P- and
S-waves exists in the upper mantle in
the western third of the United States,
with a velocity minimum at a depth of
100 to 150 kilometers. This zone
seems to be particularly pronounced
in the Basin and Range Province. The
low-velocity zone for P-waves is ap-
parently absent or greatly subdued in
the eastern two-thirds of the United
States. The most likely explanation
for the low-velocity zone is that the
mantle rocks there are partially
molten.
Continental Margin Processes
The interaction of the laterally
spreading sea floors with the con-
tinental margins — resulting in the
downward plunging of rigid litho-
spheric plates beneath the continents,
accompanied by shallow- to deep-
focus earthquakes and volcanic ac-
tivity — has been elucidated by a
beautiful synthesis of geological and
29
PART II— D'kNAMICS OF THE SOLID EARTH
geophysical evidence. The new
"global tectonics" appears to provide
an adequate explanation of the struc-
ture and continental-margin processes
of most of the circum-Pacific belt.
Along the California coast the pat-
tern is different, however. No oceanic
trench lies seaward of California, and
the earthquakes are confined to nar-
row, vertical zones beneath the San
Andreas fault system to depths that
do not exceed about 15 kilometers.
Thus, the brittle behavior of the
crust in coastal California is confined
roughly to the upper half of the crust.
Fault-plane solutions of the earth-
quakes occurring along the San An-
dreas fault system are predominantly
right-lateral strike-slip, but some solu-
tions indicating vertical fault move-
ments are also obtained. As already
noted, both geological and geophysi-
cal studies suggest that the Mesozoic
Franciscan formation of the Coast
Ranges was deposited in an oceanic
trench. These observations and in-
ferences are compatible with the con-
cept of a westward-drifting continent
colliding with an eastward-spreading
Pacific Ocean floor, resulting in conti-
nental overriding of the Franciscan
Trench and the East Pacific Rise and
development of the San Andreas sys-
tem as a complex transform fault. The
pattern of these relations is not tidy,
however, and many problems remain
to be solved in unraveling the struc-
ture and continental-margin processes
of California.
Isotopes and the Evolution and
Growth of Continents
Lead and strontium isotopic studies
of continental and oceanic rocks com-
pleted during the past decade have
contributed greatly to a better under-
standing of processes involved in the
growth and development of conti-
nents through geologic time. The
studies of continental igneous rocks
indicate addition of primitive (mantle-
derived) material and hence support
the concept of continental growth.
Lead isotope studies of feldspars rep-
resenting significant volumes of crus-
tal material place constraints on the
rate of transfer of uranium, thorium,
and lead from the mantle to the crust
and suggest early development (3,500
to 2,500 million years ago) of a sig-
nificant portion of the crust. Geochro-
nologic studies of Precambrian rocks
show that at least half of the North
American crust was present 2,500
million years ago, lending support to
this thesis.
Lead and strontium data obtained
on young volcanic rocks in the oceanic
environment have provided direct
information on the existence of sig-
nificant isotopic and chemical hetero-
geneities in the upper mantle. Sys-
tematics provided by these decay
schemes allow estimates on the times
of development and preservation of
these chemical heterogeneities, many
of which must have been generated in
Precambrian time. If a dynamic crust-
mantle system is assumed, the data
for the oceanic environment can be
interpreted as reflecting events related
to the development and growth of
continental regions.
Studies of volcanic rocks being
erupted at the continental margins
allow an isotopic evaluation of the
concept of ocean-plate consumption
in this environment. Lead isotopes in
volcanic rocks of the Japanese arc are
compatible with partial melting of
the underthrust volcano-sedimentary
plate. Strontium isotopes in calc-
alkaline rock series have placed sig-
nificant constraints on the basalt-
hybridization theory and the concept
of partial melting of older crust, how-
Local studies of lead and strontium
in continental igneous rocks have al-
lowed evaluation of the involvement
of crustal material in the genesis and
differentiation of these rocks. The
studies are circumscribed, however,
by the lack of chemical and isotopic
knowledge of the lower crust. If the
isotopic anomalies of some conti-
nental rocks are related to generation
in, or assimilation of, the lower crust,
this region must be characterized
by low uranium/lead and rubidium/
strontium ratios relating to earlier
depletion of uranium and rubidium,
perhaps at the time of initial crustal
formation.
Although these isotopic studies
have provided many answers, they
have also generated new questions
and problems. Continued work on
oceanic volcanic rocks and ultra-
mafic rocks of mantle mineralogy are
needed. High-pressure experimental
work to determine trace-element par-
titioning in the mantle is needed to
make full use of the isotopic variations
that have been observed. Chemically
and isotopically, less is known about
the lower crust than the upper mantle
and upper continental crust. Direct
sampling of this environment is a dis-
tinct possibility with modern drilling
technology; it would provide sorely
needed information not only from the
isotopic standpoint but also for many
other earth-science disciplines.
Tectonics and the Discovery of
Mineral Deposits
Adequate supplies of mineral raw
materials are essential to our econ-
omy, but they are becoming increas-
ingly difficult to find as we are forced
to seek ore deposits that offer only
subtle clues to their existence and lo-
cation. The science of ore exploration
is advancing rapidly, however. And
as it does, more is being learned of
the basic principles controlling the oc-
currence and distribution of ore de-
posits and their relation to continental
structures. Economic geologists are
increasingly adept at predicting where
deposits are apt to occur — where in
terms of geologic and tectonic envi-
ronment and where in terms of geo-
graphic areas.
The essential first step toward in-
creasing our knowledge in this field is
to plot known mineral deposits and
30
CONTINENTAL STRUCTURES AND PROCESSES AND SEA-FLOOR SPREADING
districts on a geologic-tectonic map.
This effort is well under way. Ameri-
can geologists are participating in an
international committee for the Geo-
logic Map of the World, sponsored
by a commission of the International
Union of Geological Sciences which is
compiling a world metallogenic map.
A first version of the North America
map has been completed.
Although the scale of the map
(1 : 5,000,000) necessitates severe
condensation of data, the general dis-
tribution of many ore types can be
represented and compared. For ex-
ample, the relation of the strata-bound
massive sulfide deposits to volcanic
(eugeosynclinal) belts of Precambrian
rocks in the Shield, Paleozoic rocks in
the Appalachians, and Mesozoic rocks
in the Cordillera shows rather clearly.
Nickel sulfide ores are distributed
around the periphery of the Superior
Province. A rather distinct class of
magnetite-chalcopyrite replace-
ment deposits in carbonate rock seems
to follow the Cordilleran margin of
the continent. Tungsten deposits lie
east of the quartz-diorite line. Many
epigenetic deposits in the interior of
the continent seem related to trans-
verse structures (lineaments), and a
suggestion of zonation on a conti-
nental scale seems to be emerging.
Further refinement of the metal-
logenic map is under way. In combi-
nation with general studies of conti-
nental processes and structures, this
will enable exploration geologists to
locate promising areas in which to
search for additional mineral deposits.
Needed Research on
Continental Processes
The Continental Margins — The
concepts of global plate tectonics for
the first time give earth scientists a
general working hypothesis to explain
the varied continental processes that
characterize the mountain-building as-
sociated with active continental mar-
gins: transcurrent faulting, volcanism,
thrust faulting, and the like. Clearly,
an intensification and broadening of
geological and geophysical research
along continental margins such as the
coastlines of California, Oregon, and
Washington is critically needed.
Geologic Processes in the Conti-
nental Interior — All earth scientists
recognize that the continental plates
have been actively deformed, and that
concepts of rigid continental plates
must be modified in practice. In par-
ticular, many students of the geology
of the western United States recognize
that the continental crust in and west
of the Rocky Mountains has been ac-
tively deformed over the past 100 mil-
lion years or so, and is still being
actively deformed in many places.
Plate tectonics is not irrelevant, how-
ever. Application of the attitudes and
study methods that led to the con-
cepts of global plate tectonics can be
expected to lead to significant and
dramatic advances in our knowledge
of continental processes.
If the westward-drifting continent
overrode the eastward-spreading Pa-
cific Ocean plate and continental mar-
gin features such as oceanic ridges
and trenches, where are these features
now? Is the Basin and Range Province
behaving similarly to a spreading
ocean floor? If so, where are the
spreading centers? Are they along
the Wasatch Mountain front, or the
Rio Grande rift zone? What dynamic
continental processes are occurring
east of the Rocky Mountains, and
how do they relate to the active
processes of the western crust?
Seismic Monitoring — Seismology
is now being focused in unprecedented
detail on the active continental proc-
esses along the California continental
margin. A similar focusing of seis-
mological effort on the earthquake
zones of Washington and the conti-
nental interior is needed. In particu-
lar, intensification of seismological
effort is recommended for the Ven-
tura-Winnemucca earthquake zone of
California and Nevada; the Rocky
Mountain zone of Arizona, Utah,
Idaho, Wyoming, and Montana; the
Rio Grande rift zone of Colorado and
New Mexico; the Mississippi Valley
earthquake zone of Illinois and Mis-
souri; and the earthquake zones of
the New England region. Seismic
monitoring should be accompanied by
measurements of crustal strain and
appropriate geological and geophysi-
cal exploration of major crustal fea-
tures.
Structural and sedimentary basins,
in which large reserves of petroleum
and other economic fuels and minerals
are concentrated, are among the most
prominent and significant geologic
features of the continents, but the
processes of their formation are poorly
understood. An intensive three-
dimensional study of all aspects of the
development of one or more struc-
tural and sedimentary basins through
geologic time, relating that develop-
ment to economic deposits and envi-
ronmental assets and liabilities perti-
nent to wise long-term use of the
land, would make a great contribution
to our knowledge of continental proc-
esses. The beginning of such a study
has been made in the Wind River
Basin of central Wyoming, but this
study has been concentrated mainly
on the upper part of the earth's crust.
Basin development is necessarily con-
trolled by upper-mantle as well as
crustal processes, and therefore de-
tailed geophysical study of the deep
crustal and upper-mantle foundations
of one or more large basins is needed.
Deep Continental Drilling — Our
knowledge of the composition of the
lower continental crust is clearly in-
adequate. In addition to more detailed
geophysical exploration of the deep
crust, a program of deep continental
drilling is critically needed. Locations
for penetrating the lower crust that
will be within the reach of present
drilling technology can be selected
from geophysical studies.
Geochemical Research — Although
we have good qualitative understand-
ing of the major features of the geo-
31
PART II— DYNAMICS OF THE SOLID EARTH
chemical cycles, we are still deficient
in detailed quantitative knowledge of
the geochemical cycles of practically
all elements. Research on geochemical
cycles of the elements, such as es-
sential carbon, for example, should be
intensitied. Research on the behavior
of fugitive constituents (e.g., water
and sulfur dioxide) in igneous and
metamorphic processes is also criti-
cally needed to improve our under-
standing of continental geochemical
processes and their relations to tec-
tonics.
If research on continental struc-
ture and processes is intensified and
strengthened, we can expect the
1970's to be as exciting a decade of
discovery for the continents as the
1960's were for the oceans and the
continental margins.
Practical Implications of Major Continental Processes
Recent verification that the crust of
the earth moves readily over the
earth's interior in the form of large
sliding plates has reoriented geologi-
cal thinking in a number of ways
that affect our understanding of where
many natural resources occur. We
also have new insights into such
natural hazards as biological extinc-
tions, the development of ice ages,
major earthquake belts, and regions
of volcanism, to cite just a few natural
hazards that are of continuing inter-
est. In fact, the new ideas of conti-
nental drift and sea-floor spreading
have demanded a re-evaluation of
many of the premises underlying the
subjects of geology, geochemistry,
oceanography, and long-term changes
in atmospheric circulations.
Resource Distribution
Much of our information on geo-
logical and geochemical distributions
comes from a study of ancient sys-
tems that have existed over great
lengths of geological time. In many
instances, it is clear that these ancient
systems operated differently from
those of today. It now appears that
the earth's sliding-plate mechanism
has caused relative motions between
continental and oceanic regions,
formed and destroyed ocean floors,
developed mountain belts, and
changed the positions of land masses
with respect to the equator or to the
poles in times that are short com-
pared to the time it took to form
many of our major natural resources.
Evidence is building up that we are
currently in a stage in earth history
that is considerably more active than
that pertaining over much of the geo-
logical past. It is beginning to appear
that mountain belts are longer and
higher, earthquake activity greater,
and a large array of other features
more pronounced in present times
than in an average geological period
in the past. Furthermore, by relative
motions between the continental land
masses and the pole of rotation of
the earth, it seems that climates may
have changed rather radically in the
recent geological past.
This means that we must take a
new look at theories of the origin of
many mineral deposits, natural fuels,
and surface deposits, so that we may
better predict their locations and ex-
tensions. For example, it is clear that
the petroleum deposits in the Prudhoe
Bay area of Alaska were formed at
much lower latitudes, the potash
salt deposits of Saskatchewan were
formed closer to the equator, and the
onset of the devastating ice ages was
brought about by shifts in oceanic
circulation resulting from shifting
land masses. It is necessary to know
these correlations if we are to under-
stand the processes that cause the de-
velopment of petroleum and salt de-
posits, polar ice-caps, and many other
resources or hazards that are of con-
cern to man.
Minerals — The new understand-
ing of the down-thrusting of ocean
floor beneath continental edges has
led to correlations between these
zones of downward motion and a
superjacent distribution of certain
types of mineral deposits. For ex-
ample, it has been discovered that
copper deposits of the type found in
the southwestern United States, which
supply most of our copper today,
occur in belts that lie above these
zones and that the age of emplace-
ment of the deposits generally coin-
cides with the time of the down-
thrusting movement. Thus, it appears
that the disappearance of crust, the
development of volcanoes, and asso-
ciated mineral deposits are tied to-
gether by a process that involves the
melting and fractionating of down-
dragged materials. This has led to
much prospecting activity in regions
where the downward disappearance
of crust is known from large-scale
effects. The result has been the devel-
opment and discovery of a number of
new, hitherto unsuspected deposits.
Another way of seeking new areas
for prospecting has been the predic-
tion of extensions of known mineral
belts where they occurred before con-
tinental land masses were separated.
For example, South America fitted
into Africa in a single supercontinent
not too long ago, geologically speak-
ing. (See Figure II-4) The locations
of gold, manganese, iron, tin, ura-
nium, diamonds, and other mineral
deposits in Africa are much better
known than those in South America,
although it is expected that South
America's mineral potential east of
the Andean chain will eventually be
32
CONTINENTAL STRUCTURES AND PROCESSES AND SEA-F1
Figure 11-4— CONTINENTAL DRIFT
TODAY
In 1912 Wegener noted the striking similarity in the shape of the coastline of the
Americas and of Europe and Africa. He suggested that at one time there had been
a single supercontinent as shown in the upper left of the figure. Wegener postulated
that the landmass broke up and allowed the continents to drift apart as shown in the
upper right until they assumed the position of today.
The same applies to sediment
cumulations and potential depths of
gas accumulation in such regions as
the North Sea, where reserves of
natural gas are now a substantial fac-
tor in the economies of neighboring
countries.
Thermal Water — An example of
the possibility of unexpected return
from the study of major crustal proc-
esses is seen in the power potential of
the thermal waters of the Salton Sea
area in California. Lower California
is splitting off from the mainland by
the same process of sea-floor genera-
tion as in the mid-Atlantic — namely,
by the upwelling of hot rock materials
from depth. This zone of upwelling
and splitting apart continues up the
Gulf of California and into the conti-
nental region underlying the Imperial
Valley, undoubtedly causing the great
fault systems that have produced the
California earthquakes.
The heated waters resulting from
thermal upwelling represent a great
power potential. It is estimated, for
example, that the power potential in
the Salton Sea, Hungary, and other
regions where there are large, deep
reservoirs of heated water is of the
same order of magnitude as the
known oil reserves of the earth.
Steamwells and natural geothermal
heat have been exploited commercially
in volcanic regions of Italy, Iceland,
and New Zealand, and on an experi-
mental basis in the Salton Sea area.
as great as in comparable regions of
Africa. Prospecting for mineral belts
in northeastern Brazil, the Guianas,
and southern Venezuela in areas as-
sumed to be extensions of African
belts has begun to disclose similar
deposits.
Petroleum and Natural Gas — Sim-
ilarly, where continents have been
broken apart by rifting motions with
the development of a seaway, the new
edges are subject to the deposition of
shelf-type sediments. Prior to the
understanding of continental drift,
many of these continental shelves
were believed to be ancient. Now it is
known that all such new edges are
bounded by thick sections of younger
sediments which may have oil-bearing
potential. This knowledge, coupled
with the geological information pro-
vided in anticipating depths of drilling
as well as structures, has led major oil
companies to undertake a worldwide
prospecting program. The result has
been the discovery of new areas of
economic importance.
Environmental Pollution
Nature is the greatest polluter of
the environment. Geochemical proc-
esses have concentrated radioactive
elements at the surface, so that man
is constantly bombarded by a gamma-
ray flux much larger than the average
for the earth as a whole. Streams and
rivers carry rock flour from the action
of glaciers in high latitudes and
hydrated ferric oxides, clays, and
other debris in lower latitudes to such
an extent that deltaic and coastal de-
posits cause problems for shipping
33
PART II— DYNAMICS OF THE SOLID EARTH
and water transport, harbors, and re-
sort beaches. When a drainage system
cuts through a large mineral deposit,
it dumps its load of partially oxidized
and soluble metal salts into down-
stream waters.
In order to measure environmental
pollution and change, it is necessary
to know the base levels of natural
pollution and their distributions and
dynamics in space and time. The
response to thermal pollution in rivers
can be predicted on the basis of ob-
serving the ecology of warm waters
in tropical regions. The same applies
to oceanic waters. Natural variations
in radioactivity provide us with sta-
tistics on the effect of a widely
dispersed distribution of radioactive
wastes. Variations in the trace-ele-
ment abundances in natural waters
and soils give us an insight into the
effect of these on biological systems.
Thus, it can be said that a study of
the geochemical and geological dis-
tributions and processes forms a nec-
essary base for the observation of
perturbations to the natural levels
and rates.
Atmospheric Changes
The history of climatic change, as
different land masses approached or
receded from the equator, has left its
record on the ecology and on surface
deposits. In addition, evolutionary
change of living organisms has super-
imposed progressive changes in the
chemistry of the earth's surface.
Thus, early in earth's history, great
thicknesses of banded iron formations
resulted from a combination of evolv-
ing bioorganisms and the atmosphere
of the time.
Atmospheric change has been
closely coupled with the evolution of
photosynthesis processes and, more
recently, with the nature and extent
of land areas in the more tropical
regions of the earth. There is good
evidence to indicate that the partial
pressures of oxygen and carbon diox-
ide in the atmosphere are significantly
different from those in the past, with
some estimates indicating a drastic
variation in the content of oxygen in
particular. An understanding of the
balance between major tropical forest
areas, such as in the Amazon region,
and the partial pressure of oxygen in
the atmosphere would be of some sig-
nificance. But precise measurements
of the rate of change of oxygen
partial pressure with the oxygen-
generating living systems on land and
in the oceans have not been made on
a time-scale of interest to human
existence. We therefore know little
of the short-term effects that might
result from a substantial change in
human land use.
34
3. EARTHQUAKES
Earthquake Prediction and Prevention
The earthquakes that we are really
interested in predicting are the largest
ones, those capable of taking human
life and causing property damage.
Earthquakes of this size have occurred
countless times in the past few million
years, mostly in relatively narrow
belts on the earth's surface.
The destructive powers of earth-
quakes and resulting tsunami waves
are well known. For example, the ex-
tremely destructive Alaskan earth-
quake of 1964 killed about 100 people
and caused measurable damage to
75 percent of Anchorage's total de-
veloped worth. The earthquake also
generated tsunamis that caused se-
vere damage throughout the Gulf of
Alaska, along the west coast of North
America, and in the Hawaiian Islands.
A very severe earthquake in 1960
killed approximately 2,000 people in
Chile and rendered about a half mil-
lion people homeless. Property dam-
age was estimated to be about $500
million. Tsunami damage from this
earthquake occurred along the shores
of South America, certain parts of
North America (principally southern
California), the Hawaiian Islands,
New Zealand, the Philippines, Japan,
and other areas in and around the
perimeter of the Pacific Ocean. About
$500,000 damage was suffered by the
southern California area, while about
25 deaths and $75 million damage
were suffered by the Hawaiian
Islands. The Philippines incurred
about 32 deaths. Japan sustained ap-
proximately $50 million damage.
Earthquake Zones — There are two
catastrophe-prone zones (see Figure
II-5) : first, a region roughly encom-
passing the margin of the Pacific
Ocean from New Zealand clockwise
to Chile, including Taiwan, Japan,
and the western coasts of Central and
South America; and second, a roughly
east-west line from the Azores to
Indonesia and the Philippines, includ-
ing Turkey and Iran and the earth-
quake zones of the Mediterranean,
especially Sicily and Greece.
The parts of the United States with
a history of severe earthquake inci-
dence are the Aleutians, south and
southeastern Alaska, and the Pacific
coast of continental United States.
The two worst earthquakes of the
twentieth century in this country
were the "Good Friday" quake near
Anchorage, noted above, and the San
Francisco quake of 1906. In terms
of energy release, the 1964 shock may
have been two or three times as
potent as that of 1906.
Statistical Generalities — The prob-
lem of earthquake prediction is closely
related to statistical studies of earth-
quake occurrence. Such studies en-
able us to make the following gen-
eralizations:
1. Somewhere on the earth there
will be a catastrophic earth-
quake, one capable of causing
death in inhabited areas, on the
average of between 2 and 100
times a year. Greater precision
is not possible, since a strong
earthquake in a sparsely popu-
lated area will create no major
hazard, while the same earth-
quake in a densely populated
region may or may not cause
loss of life, depending on how
well the buildings are con-
structed.
2. In any given region in the
earthquake-prone zones, a cata-
strophic shock will occur on
the average of once per so
many years, depending on the
size of the region and how
active it is.
But statistical prediction of this
sort is unsatisfactory for an inhabi-
tant of a specific region. This person
is most concerned with his own region
and with a time-scale of much less
than 100 years. This person probably
needs several months' advance notice
of an impending earthquake, although
we are nowhere near that goal.
Even if it were possible to predict
an earthquake to the nearest minute
or hour, major sociological problems,
of the sort associated in the United
States with civil defense, would need
to be solved. What kind of warning
system should there be? How does
one handle the dispersal of the crowds
involved in possible mass exodus?
And what would be the reaction of
the public if predictions failed to
prove out in, say, 25 percent of the
cases?
Why Earthquakes Occur
The occurrence of earthquakes in-
volves the physics of friction. Accord-
ing to the modern theory of rigid-plate
tectonics, the earth's surface is cov-
ered with a small number of relatively
rigid, large plates all in motion rela-
tive to one another. At some lines of
contact between two plates, the plates
are receding from one another and
surface area is being created by the
efflux of matter from the earth's in-
terior. Along other lines, plates are
approaching one another, area is being
destroyed, and surface matter is being
returned to the interior. Along a third
class of contacts, area is neither cre-
ated nor destroyed, and the relative
motions are horizontal.
35
PART II— DYNAMICS OF THE SOLID EARTH
Figure 11-5— SEISMICITY OF THE EARTH
Earthquakes occur in well-defined zones where the plates adjoin. The character
of the earthquakes varies with the nature of the plates' contact.
However steady the slow motion
of the plates at their centers, the
motions are not steady at their edges.
As the giant plates move relative to
one another, they rub against their
neighbors at their common edges.
The friction at the edges seizes the
plates and allows the accumulation of
stress at the contact. When the stress
at these contacts exceeds the friction,
the contact breaks, a rupture takes
place, and an earthquake occurs. (See
Figure II-6)
A map of earthquake locations,
therefore, is actually a map of the
plates, and the character of earth-
quakes varies with the nature of the
plates' contact. The character of the
earthquakes in the Aleutians and
along the San Andreas Fault of Cali-
fornia are significantly different, for
example: the first is a zone of com-
pression with surface area being con-
sumed, while the second is a zone of
relative horizontal motions with con-
servation of area.
Approaches to Earthquake
Prediction
The prediction problem is, there-
fore, the problem of finding a way to
determine the first breakage of the
frictional contact between two plates
at a particular point along the plate
boundary. This problem can be ap-
proached by three methods: a search
for premonitors, stress measurement,
and historical studies.
Search for Premonitors — When
solids approach the breaking point,
they enter a nonlinear regime of plas-
tic deformation in which the physical
properties of the materials change
markedly. Although the stresses con-
tinue to accumulate at a constant rate,
the strains increase greatly prior to
fracture. Indeed, in some cases, much
of the deformation observed in earth-
quakes is not associated with abrupt
displacements in rupture but is due
to "creep" — i.e., plastic deforma-
tion — certainly occurring after, and
probably occurring before, the shock.
Pre-shock creep has been observed in
laboratory experiments on fracture
and has been reported by Japanese
seismologists prior to some Japanese
earthquakes.
36
Figure 11-6— THE UPPER MANTLE IN THE REGION OF FIJI-TONGA-RARATONGA
INDIA PLATE
FIJI
TONGA TRENCH
^* —
PACIFIC PLATE
LITHOSPHERE
ASTHENOSPHERE
RAROTONGA
•j\'
NEW ZEALAND
This figure depicts an area where the Pacific plate (east of the Tonga trench) meets
with the India plate, pushing the lithospheric mass of the Pacific plate downward
forming the Tonga trench. Earthquakes take place all along this zone, closer to the
surface near the trench and at progressively greater depth beneath the continental
(India plate) mass.
Changes in the rate of strain are
another potential premonitor. These
changes would be accompanied by an
increase in the rate of occurrence of
microearthquakes — i.e., very small
earthquakes that are indicators of
"creaking." The U.S. program for
earthquake prediction has a strong
component devoted to the problem of
detecting changes in rates of strain
along parts of the San Andreas fault
system, including triangulation and
leveling, tilt, distance measurements,
and microearthquake observations.
Some intermediate-sized earthquakes
have been preceded by observed in-
creases in rates of microearthquake
activity and by increases in the strain
rate, as measured by changes in the
lengths of reference lines drawn
across known faults and by changes
in the tilt rate.
Other physical properties in the
vicinity of earthquake faults may
change prior to rupture. These in-
clude magnetic susceptibility, elec-
trical resistivity, and elastic-wave
velocities. There is one, as yet un-
duplicated, example of a Japanese
earthquake preceded by major changes
in the local magnetic field. A minute
change in the magnetic field has also
been noted in the neighborhood of
one part of the San Andreas Fault
about one day before each of several
microearthquakes occurred. Changes
in the other properties have been ob-
served in laboratory experiments on
rock fracture but have not been veri-
fied in earthquake examples.
Stress Measurement — There is
considerable debate about the values
of the critical stress required to cause
rupture. Seismological estimates place
the stress drop at about 10 to 100
atmospheres (bars). Laboratory ex-
periments show the stress drop to be
perhaps one-fourth the shear stress
across the frictional surface, although
there appears to be some seismologi-
cal evidence that the fractional stress
drop rises with increasing earthquake
magnitude. In any event, the overbur-
den pressure should be enough to
seal faults shut, and no earthquakes
should occur below about 2 kilome-
ters. But earthquakes do occur below
this depth. Thus, one must find some
reason why friction at depth is re-
duced. One way of doing so is to
invoke the role of water as an impor-
tant lubricant: that is, rocks lose
some or all of their shear strength
when interstitial water is raised in
temperature.
No major progress has yet been
made on in situ measurement of shear
stress and determination of pore
water pressure and temperature (to
determine critical shear rupture
stress). In principle, direct stress
measurement may be the simplest
way to predict earthquakes, but it
may also be the most difficult to
effect in practice.
Historical Method — In this case,
we ignore the physics of the earth-
quake mechanism in large part, and
concentrate instead on the history of
earthquake occurrence (seismicity) as
a mathematical sequence. We can
then investigate this historical se-
quence for regularities — if any are
present. The search may take two
forms: (a) a search for triggering
effects — i.e., a tendency for earth-
quakes to occur at certain preferred
times; and (b) a search for organiza-
tion within a local catalog.
Triggering is a cross-correlation
problem in which two time-series are
compared, one of which is the catalog
or compilation of the earthquake his-
tory for a particular region. No sig-
nificant triggering effects have yet
been found, although the earth tides
should be the most likely candidate.
In a number of cases, earthquake
activity at a distance from a given
region seems to be reduced following
a large shock. However, this effect
may be "psychoseismological": that
is, seismologists are more likely to
report aftershocks in an active area
and to neglect reporting for other
areas. Furthermore, the occurrence
of a large shock in one region will
reduce the tendency for another to
occur in the same region, and will
37
PART II— DYNAMICS OF THE SOLID EARTH
increase the likelihood of a shock
occurring in a neighboring region
over a time-scale of several years.
Organization is an auto-correlation
problem — i.e., one must search for
predictive elements in the time-series
of shocks for a given region within
the series itself, without benefit of
comparison with other time-series.
Although a given earthquake catalog
does not appear to be wholly random,
the "signal-to-noise" ratio is small.
The differences from randomness are
small, and the problems of extracting
the organized part from the random
part has not yet been solved.
The Limits of Prediction
dictive capabilities for the second and
succeeding large shocks, after the
next one has occurred, will be much
better on all accounts, for we will
then know what we are looking for.
In Stable Regions — Problems of
prediction are difficult enough in
regions of high activity such as the
circum-Pacific belt. They are almost
impossible in regions with little or no
history of seismicity. For example,
the region from the Rocky Mountains
to the Atlantic Coast is supposed to
be stable; yet two of the greatest
earthquakes in U.S. history occurred
east of the Rockies. Destructive
earthquakes of record occurred in
southeastern Missouri in 1811 (the
shock was felt over an area of two
million square miles; it relocated the
Mississippi River) and near Charles-
ton, South Carolina, in 1886.
Seismic-risk studies show the New
York area to have a hazard roughly
100 times smaller than southern Cali-
fornia. Does this mean that the larg-
est shocks on the southern California
scale would recur in the New York
area at an interval of 10,000 years?
Or are the largest possible shocks for
the New York area less than the larg-
est for southern California? The 1811
and 1886 experiences show that stable
regions are not immune. But we still
have no way of determining where in
stable United States a great earth-
quake is likely to occur — or when.
(See Figure II-7)
In Active Areas — All three meth-
ods of prediction in active areas share
one major difficulty: even in Cali-
fornia, where most U.S. activity in
prediction research is concentrated,
the rate of occurrence of truly large
shocks is small.
We have not had a great earth-
quake in California since careful seis-
mological records began to be kept.
The three great historical shocks —
San Francisco (1906), Lone Pine, or
Owens Valley (1872), and Fort Tejon,
near Los Angeles (1857) — all oc-
curred in earlier times. The historical
method postulates that the order of
small- and intermediate-sized shocks
can be used to predict when large
shocks will occur. However, seis-
mologists do not really know what
they are looking for, since a large
shock has not taken place in the
modern era of California seismology.
The same criticism applies to the
other two methods. In the search for
premonitory effects and the measure-
ment of in situ stress, the presumption
is that the anomalous, or critical, states
will be obtained for the large shock
by studying these states for the small
or intermediate shocks. Whether this
is correct or not will be seen after
the next large shock. Indeed, our pre-
Figure 11-7— SEISMIC RISK IN THE UNITED STATES
J NO DAMAGE
MINOR DAMAGE
INTENSITIES V AND VI
MODERATE DAMAGE
INTENSITY OF VII
MAJOR DAMAGE
INTENSITY OF VIII AND HIGHER
This figure delineates the areas where earthquakes have occurred and have caused
damage within the United States. The range is from areas of no damage in southern
Texas and Florida to areas of major damage such as the western coast of California.
Intensities are measured from 0 to 8 in terms of the Richter scale.
38
Minimizing Earthquake Damage
About 10,000 people a year die as
a consequence of earthquakes. Most
of them live in underdeveloped parts
of the world, where housing is not
well constructed; indeed, the United
States and Canada may be among the
few places in the earthquake zones of
the world where building construction
is even slightly seismo-resistant, be-
cause reinforcing steel is used in
public buildings and wood framing
in private residences in the seismic
zones.
Much more needs to be done, how-
ever. Structural engineers can now
determine the response of a building
to a given excitation with reasonable
accuracy. The basic problem remains
that of knowing what the ground
motion will be in a large earthquake,
so that appropriate building standards
can be established. Some measure-
ments of ground motion in earth-
quakes of intermediate size are avail-
able, but there are no good records
for large shocks. In California, the
next great shock may cause property
damage amounting to billions of dol-
lars. Loss of life may well be in the
thousands. Some of this hazard can
be reduced if appropriate changes in
the building codes for new con-
struction are made with the aim of
minimizing casualty from great earth-
quakes.
Until now, there has been severe
disregard of the earthquake hazard.
Tracts of homes are built within a
few feet of the trace of the 1906 San
Francisco earthquake, for example.
This section of the fault has remained
locked since lq06, but some creep
has recently been observed. Accelera-
tion of the creep could imply a sig-
nificant hazard in an important urban
area.
"Man-Made" Earthquakes
Some natural earthquakes have
been triggered by man. The trigger-
ing agents have included underground
nuclear explosions, the filling of dam
reservoirs, and the injection of water
into porous strata. In all cases, the
earthquakes occurred near the trigger-
ing agent. In all cases, the energy re-
leased in the earthquake was already
stored in the ground from natural
sources.
The water-injection case that oc-
curred near Denver, Colorado, is of
considerable interest. In that case, it
can be surmised that the water in-
jected into a shallow well at the Rocky
Mountain Arsenal between 1962 and
1965 lowered the friction on a pre-
existing fault and allowed a series of
earthquakes to be initiated. The oc-
currence of shocks was correlated to
the pumping history in the well. They
showed an increasing migration with
time and an increasing distance from
the well — all this in a region with no
previous history of earthquakes. In
this case, the water seen
acted as a lubricant to reduce
tion. The migration of the shocks
was due to stress propagation by
concentrations at ends of ruptured
segments.
Can Great Earthquakes be
Prevented?
Although these earthquakes were
triggered by man in his usual way of
modifying the environment without
thought for the consequences, the
experience in Colorado prompts an
interesting speculation. Suppose, for
example, one were to envision the
following situation some years from
now: Pumping stations are located
astride all the major earthquake zones
of the world. They serve to raise the
water pressure on the fault surfaces
several kilometers below the surface,
thereby reducing the friction. The
large plates are thus lubricated and,
without the friction at their edges,
they move at faster rates than at pres-
ent, releasing the accumulated stress
in a series of small, harmless earth-
quakes and avoiding the human toll of
destructive, catastrophic earthquakes.
There are many years of research
between the first bit of serendipity at
Denver and this fantasy, however. In
the meantime, work on the prediction
problem must go ahead until the solu-
tion to the prevention problem makes
prediction gladly meaningless.
39
4. VOLCANOES
Volcanoes and Man's Environment
In many parts of the world vol-
canoes are an important part of man's
environment. They are usually con-
sidered destroyers. But although vol-
canoes do a great deal of damage, and
have taken many thousands of lives
over the past few centuries, they are
benefactors in the long run.
Volcanic regions, especially those
in which the surface has been covered
with volcanic ash, tend to be very
fertile. The effect is most marked
in tropical regions where leaching
rapidly removes plant nutrients from
the upper part of the soil; there, new
ash falls restore the lost materials. A
close correlation between population
density and soil type has been shown
in Indonesia, for example, with by
far the densest populations in areas
where very young or still active vol-
canoes have added ash to the soil.
World over, the agricultural popula-
tion clusters in the most fertile re-
gions; it is likely to do so increasingly
as population grows and food supplies
become less adequate. Yet some of
the most fertile areas, close to active
volcanoes, are the most subject to
volcanic destruction. Furthermore,
volcanoes that have been quiet for
centuries may still be active and may
erupt again. In order to continue to
make use of these badly needed rich
agricultural areas close to volcanoes,
we must learn to forecast volcanic
activity, and to deal with it when it
comes.
A Brief Overview
Volcanoes are places where molten
rock or gas, or usually both, issue at
the surface of the earth. As the
molten rock, known as magma, rises
from depth, it contains dissolved
gases; but as the magma enters zones
of lesser pressure near the earth's sur-
face, some of the gas comes out of
solution and forms bubbles in the
liquid. The bubbles tend to escape
from the magma, but in order to do
so they must move to the upper sur-
face of the liquid and rupture the
surface. When the viscosity of the
magma is relatively low — as it is,
for example, at Kilauea Volcano, in
Hawaii — the bubbles escape easily;
but when the viscosity is high, they
escape less readily and accumulate in
the magma instead, their size and
pressure increasing until they are able
to burst their way free. This produces
an explosion. Thus, volcanic erup-
tions may consist of a relatively gentle
outwelling or spurting of molten rock,
which flows away from the vents as
lava flows, or of violent explosions
that throw shreds of the molten rock
or solid fragments of older rock high
into the air, or of any mixture of
the two.
The fragments thrown out by ex-
plosions are known as pyroclastic
material. The large fragments are
bombs, blocks, scoria, or cinder; the
sand- to dust-size material is called
volcanic ash. Some eruptions dis-
charge mostly gas; and gas is given
off, sometimes copiously, by many
volcanoes between eruptions.
The fact that a volcano has not
erupted for centuries does not make
it less dangerous. We have many ex-
amples of volcanoes that have been
dormant for hundreds of years, only
to return to life with catastrophic
eruptions. At the beginning of the
Christian era, Vesuvius had been quiet
for hundreds of years; but in a.d. 79
it erupted, destroying all the agricul-
tural land on its flanks and close to its
base, and the cities of Pompeii, Her-
culaneum, and Stabia. The greatest
eruption of recent years, at Kam-
chatka in 1956, took place at a long-
inactive volcano that had been given
so little attention that it had not even
received a name. The name we use
for it today, Bezymianny, means "no
name." Many other examples could
be given, including that of Arenal, in
Costa Rica, in 1968.
Within the U.S., the active vol-
canoes of Hawaii and Alaska are well
known. Familiar, too, is the line of
great volcanic mountains along the
Cascade Range, from northern Wash-
ington into northern California. Al-
though the latter are not usually con-
sidered to present any volcanic risk,
they really do. Several eruptions have
taken place in the Cascade Range in
the past 170 years, the latest at Lassen
Peak, California, during the years
1914 to 1919. Six thousand years ago
a tremendous eruption at the site of
the present Crater Lake, in Oregon,
covered hundreds of thousands of
square miles with ash and devastated
the area immediately around the
mountain. Other Cascade volcanoes
may behave similarly in the future.
Several appear to be in essentially the
same state as Mt. Mazama, at Crater
Lake, before its great eruption.
Lava Flows
Streams of liquid rock are lava
flows. Where the magma has low
viscosity and the supply is large, a
lava flow may spread for tens of
miles. Some flows in the Columbia
River lavas of Washington and Ore-
gon have been traced for distances of
more than 100 miles and over areas
of more than 10,000 square miles.
Since 1800, lava flows on the island
40
VOLCANOES
of Hawaii have covered more than
300 square miles of land surface.
Much of this was unused land on the
upper slopes of the mountains, but in
1955 a large part of the six square
miles buried by lava was prime agri-
cultural land. Again in 1960, several
hundred acres of rich sugar land were
covered. On the other hand, the lava
built out the shoreline of the island,
creating half a square mile of new
land.
The land buried by lava flows is not
lost forever. The rapidity with which
vegetation reoccupies the lava surface
varies greatly with climate. In warm
areas of high rainfall, plants move in
quickly. The lava flows of 1840, on
the eastern end of the island of
Hawaii, are already heavily vegetated.
In dry or cold areas the recovery is
much less rapid.
It has been found that simply
crushing the surface of the lava, as by
running bulldozers over it, greatly
speeds reoccupation by plants, appar-
ently because the crushed fine mate-
rial retains moisture. Certain types of
plants can be successfully planted on
a surface treated in this way within a
few years of the end of the eruption.
In 1840, Hawaiians were found grow-
ing sweet potatoes on the surface of
a lava flow only about seven months
old. Experimentation with ways of
treating the flow surface and with
various types of plants will probably
make it possible to use many flow
surfaces for food crops within two
years of the end of the eruption.
Methods for the Diversion of Lava
Flows — Several methods have been
suggested. In 1935 and 1942, lava
flows of Mauna Loa, Hawaii, were
bombed in an effort to slow the ad-
vance of the flow front toward the
city of Hilo. The results indicated
that, under favorable circumstances,
the method could be successful. They
also indicated, however, that not all
lava flows could be bombed with use-
ful results.
It has been suggested that lava
flows can be diverted by means of
high, strong walls, not in order to
stop the flow but only to alter its
course. Walls of this sort, although
poorly planned and hastily built, were
successful to a limited degree during
the 1955 eruption. Walls built during
the 1960 eruption were of a different
sort, designed to confine the lava
like dams rather than to divert it.
Although the lava eventually over-
topped them, they appear to have
considerably reduced the area de-
stroyed and were probably respon-
sible for the survival of a large part
of a beach community and a vitally
important lighthouse.
Whether such walls would be effec-
tive against the thicker, more viscous
lava flows of continental volcanoes is
not known. Thick, slow-moving lava
flows at Paricutin Volcano, in Mexico,
did not crush the masonry walls of a
church that was buried by the lava
to roof level. Walls generally would
be useless against lava of any vis-
cosity where the flow is following a
well-defined valley. Fortunately, the
flows of continental volcanoes usually
are shorter and cover less area than
Hawaiian flows, thus reducing the
area of risk. Much more research is
needed on ways to control lava flows.
Ash Falls
It was formerly believed that ash
from the great explosion of Krakatoa
Volcano, between Java and Sumatra,
drifted around the earth three times
high in the stratosphere. Although it
now appears that the brilliant sunsets
once regarded as evidence of this were
probably caused instead by an aerosol
of sulfates resulting from interaction
of volcanic sulfur dioxide gas and
ozone, it has been repeatedly demon-
strated that violent eruptions may
throw volcanic ash high into the
upper atmosphere, where it may drift
for hundreds of miles. For instance,
ash from the 1947 eruption of Hekla,
in Iceland, fell as far away as Mos-
cow; ash from the eruption of Qui-
zapu, in Chile, fell at least as far away
as Rio de Janeiro, 1,850 miles from
the volcano; and ash from the Crater
Lake eruption has been traced as far
as central Alberta.
Although it has not been absolutely
proved, it appears probable that large
amounts of ash in the atmosphere
affect the earth's climate. Ash from
the 1912 eruption of Mt. Katmai,
Alaska, is believed to have reduced by
about 20 percent the amount of solar
radiation reaching the earth's surface
at Mt. Wilson, in southern California,
during subsequent months; ash from
the Laki eruption in Iceland drifted
over Europe and appears to have
caused the abnormally cold winter of
1783-84. Other examples have been
cited, although some investigators
find no evidence for it.
Heavy ash falls may destroy vege-
tation, including crops, within a radius
of several miles around the volcano.
Ash from the Katmai eruption de-
stroyed small vegetation at Kodiak,
100 miles away, although bigger trees
survived. During the 1943 eruption
of Paricutin, even the big trees were
killed where the ash was more than
three feet deep. Even a few inches of
ash will smother grass.
Serious indirect consequences may
arise. A great famine that resulted
from destruction of vegetation and re-
duction of visibility to the point
where the fishing fleet could not work
followed the Laki eruption and is said
to have killed a large proportion of
the population of Iceland. Around
Paricutin, thousands of cattle and
horses died, partly of starvation and
partly from clogging of their digestive
systems from eating ash-laden vege-
tation. Even if it causes nothing
worse, ash-covered vegetation may
cause serious abrasion of the teeth of
grazing animals. Cane borers did
serious damage to sugar cane in the
area west of Paricutin, because the
ash had destroyed another insect that
normally preyed on the borers. Any
41
PART II— DYNAMICS OF THE SOLID EARTH
disturbance of the natural regime may
have surprising results!
Direct damage to fruit and nut trees
can be reduced by shaking the ash
from the branches; and collapse of
roofs of dwellings under the weight
of ash can be reduced by shoveling or
sweeping off the ash. Much addi-
tional research is needed on ways to
reduce other damage from ash.
Light ash falls are beneficial. The
ash acts as a mulch, and helps to
retain water in the soil for plant use
and to supply needed plant foods.
Within a few months after the erup-
tion, areas covered with a thin layer
of ash commonly look as though they
had been artificially fertilized. The
fertility probably could be further in-
creased by proper treatment of the
ash-covered ground.
Fragmental Flows
Glowing avalanches ("nuees ar-
dentes") are masses of red-hot frag-
ments suspended in a turbulent cloud
of expanding gas. The main portion
of the mass travels close to the
ground and is closely guided by
topography, but above it is a cloud
of incandescent dust that is much less
restricted in its spread. The ava-
lanches are exceedingly mobile; they
may travel as fast as 100 miles an
hour. Some glowing avalanches are
caused when large volumes of hot
debris are thrown upward nearly ver-
tically by explosions and then fall
back and rush down the slopes of
the volcano. This happened, for in-
stance, on the island of St. Vincent,
in the Lesser Antilles, in 1902. The
results were disastrous; thousands of
people died. The glowing avalanches
of Mt. Pelee, Martinique, in the same
year, appear to have originated from
low-angle blasts at the edge of a
steep-sided pile of viscous lava (a
volcanic dome) that grew in the crater
of the volcano. They devastated the
mountain slopes, destroyed the city of
St. Pierre, and took over 30,000
human lives. Still other glowing ava-
lanches result from collapse of the
side of the dome after it has grown
beyond the crater, or from collapse
of thick lava flows on the slope of
the volcano. Those formed by col-
lapse of a summit dome are common
on Merapi Volcano, in Java.
The association of glowing ava-
lanches with domes is so common
that any volcano on which a dome
is growing or has grown should be
suspect. Particularly where a growing
dome has expanded onto the outer
slope of the volcano, the area down-
slope is subject to glowing avalanches
and probably should be evacuated
until some months after the dome has
stopped growing and achieved appar-
ent stability.
Glowing avalanches are guided by
existing valleys, and their courses can
be predicted to some extent. The
upper parts of big ones may override
topographic barriers, however. St.
Pierre was destroyed by the upper
part of a big avalanche that continued
over a ridge while the main mass of
the avalanche turned and followed a
valley.
Ash flows resemble glowing ava-
lanches in being emulsions of hot
fragments in gas. They are also ex-
ceedingly mobile and travel distances
as great as 100 miles or more so
rapidly that, when they finally come
to rest, the fragments are still so hot
they weld themselves together. An
historical example occurred in the
Valley of Ten Thousand Smokes,
Alaska, in 1912. Older ones cover
many thousands of square miles in
western continental United States. A
fairly recent example is the Bishop
tuff in California.
The great speed of glowing ava-
lanches and ash flows probably makes
effective warning impossible once
they have started; and their great
mobility and depth appears to make
control by means of walls unfeasible.
The only hope of averting future dis-
asters seems to be in recognizing the
existence of conditions favorable to
their generation, and issuing a long-
range warning in advance of their
actual initiation.
Mudflows are slurries of solid frag-
ments in water. Not all of them are
volcanic, but volcanic ones (lahars)
are common. They may be either hot
or cold, and they may originate in
various ways: by the ejection of the
water of a crater lake, by rapid melt-
ing of ice or snow, or, most com-
monly, by heavy rains. The water
mixes with loose pyroclastic or other
debris on the sides of the volcano
and the mud rushes downslope, with
speeds of up to 60 miles an hour,
sweeping up everything loose in its
path. In the last several centuries,
mudflows have probably done more
damage, and taken more lives, than
any other volcanic phenomenon.
They were, for instance, the principal
cause of damage during the 1963
eruption of Irazu, in Costa Rica.
At Kelut Volcano, in Java, explosive
eruptions repeatedly ejected the water
of the crater lake, causing mudflows
on the flanks that took thousands of
lives and destroyed plantations and
rice paddies in the rich agricultural
area near the base of the volcano.
In 1919 alone, an area of 50 square
miles of arable land was buried and
about 5,100 persons were killed. In
an effort to improve the situation,
Dutch engineers drove a series of
tunnels through the flank of the vol-
cano and lowered the level of the
crater lake to the point that the vol-
ume of water remaining would be
insufficient to cause big mudflows.
This was effective. During the big
eruption of 1951 only seven persons
were killed, all on the upper slopes
of the volcano, and no damage was
done to the agricultural land at the
base. The eruption destroyed the
tunnel entrances, however, and they
were not reconstructed in time to pre-
vent a new disaster in 1966. A new
tunnel, completed in 1967, has again
drained the lake to a low level. As
42
VOLC,
Indonesian authorities are well aware,
the present menace on Kelut is in-
creasing as a result of the steady
increase of population on the fertile
flanks of the volcano.
In Java, attempts were made to
warn of hot mudflows by installing
thermal sensors in the upper parts of
the valleys on the slopes of volcanoes,
with an electrical alarm system in
villages on the lower slopes. It was
hoped that the villagers would have
time to reach high ground before the
mudflow arrived. In places, artificial
hills were built to serve as refuges.
The alarms were unreliable, however,
and did not work at all for cool
mudflows.
Mudflows, being essentially streams
of water, are closely controlled by
topography, and it is possible to an-
ticipate which areas are most threat-
ened. Dams built to try to contain
the mudflows from Kelut failed when
the small reservoirs behind them be-
came overfull. It might be possible,
however, in some favorable localities,
to use diversion barriers like those
suggested for Hawaiian lava flows.
In general, the best possibility seems
to be to learn to recognize the situa-
tions most likely to lead to mud-
flows, and issue warnings when these
develop.
Gases
The most abundant gas liberated at
volcanoes is water. Less abundant
are carbon gases, sulfur gases, am-
monia, hydrogen, hydrochloric acid,
and hydrofluoric acid. Sulfur dioxide
and sulfur trioxide unite with water
to form sulfurous and sulfuric acids.
The acid gases may be injurious to
plants downwind from the volcano.
Mild gas damage resembles smog
damage in cities. More severe damage
causes fruit to drop and leaves to turn
black and fall; it may kill the plant.
Serious damage of this sort has been
experienced on coffee plantations to
the lee of the volcanoes Masaya, in
Nicaragua, and Irazu, in Costa Rica,
and less severe damage has occurred
in Hawaii.
Suggested countermeasures have
included trapping the gases at the
vents in the volcanic crater and dis-
charging them at higher levels in the
atmosphere by means of a high flue,
or precipitating them by means of
chemical reactions. Valuable chemi-
cals might be recovered in the process.
Local application of chemicals directly
on the plants in order to neutralize
the acids has been tried, but this is
expensive and not wholly effective.
Further research on this subject is
indicated.
Predicting Eruptions
Accurate prediction of time, place,
and nature of volcanic eruptions would
go far toward eliminating the dis-
asters that arise from them. How-
ever, although some progress has
been made in this direction, we are
still a long way from being able to
make accurate predictions. The indi-
cations that have been used to predict
time and place of eruptions are: earth-
quakes, swelling of the volcano,
change of temperature or volume of
gas vents (fumaroles) or hot springs,
changes of elevation in areas near
the volcano, and opening or closing
of cracks in the ground.
Tumescence — Scientists of the
Hawaiian Volcano Observatory have
found that Kilauea Volcano swells up
before eruptions and shrinks once the
eruption has started. However, the
tumescence may continue for months,
or even years, before eruption finally
takes place; furthermore, it sometimes
stops and detumescence occurs with-
out any eruption. (The magma may
be drained away by intrusion into the
subsurface structure of the volcano.)
Tumescence, therefore, does not indi-
cate when an eruption will occur, but
only that the potential for eruption
is present.
Earthquakes — Some eruptions are
preceded by swarms of shallow earth-
quakes over periods of a few hours
or days. These, combined with the
swelling of the volcano, are the most
useful short-range tool for prediction.
The eruption of Vesuvius in a.d. 79
was preceded by ten years of very
frequent earthquakes, and with our
present knowledge we could probably
have made a general long-range pre-
diction that the volcano was likely to
erupt, though we still probably could
not have said just when. Other erup-
tions appear to have had no definite
seismic prelude.
Upheavals and Cracks — Marked
swellings or upheavals have taken
place before eruptions at some vol-
canoes, though more commonly none
has been detected. This may be partly
because of lack of appropriate instru-
ments in proper positions. Upheaval
of the land causes the shoreline in
the vicinity of Naples to shift seaward
a few hours or days before some erup-
tions of Vesuvius. A similar upheaval
preceded the eruption of Monte
Nuovo, in the Phlegrean Fields north-
west of Naples, in 1538. In 1070 the
region was again being upheaved,
with the opening of cracks and in-
crease of fumarolic action in the
nearby crater of Solfatara Volcano;
these things suggested strongly that
an eruption would take place in the
area soon.
Tilt Tatterns — In 1943, at Showa
Shin-Zan, in Japan, the ground sur-
face was pushed up to form a bulge
150 feet high and 2V2 miles across
before the eruption finally started.
The 1960 eruption of Manam Vol-
cano, near New Guinea, was preceded
by a large number of earthquakes
and tumescence that resulted in tilting
of the ground surface through an
angle ranging from 8 to 18 seconds of
arc. Tilting of the ground surface has
been observed before eruptions at
some other volcanoes, but it has not
43
PART II— DYNAMICS OF THE SOLID EARTH
been found commonly. In retrospect,
workers at Nyamuragira Volcano, in
central Africa, believed that swarms
of earthquakes would have made it
possible to predict the 1958 eruption
about 30 hours before the outbreak,
but no such prediction was made. At
most volcanoes, including most of
those in western United States, the
instrumental installations necessary to
recognize either earthquake preludes
or diagnostic tilt patterns are still
lacking.
History — The prediction of the
type of eruption rests almost wholly
on a knowledge of the past history of
the volcano. What has happened be-
fore is most likely to happen again.
In most instances, however, the his-
tory must be deduced from careful
geological studies, and we still do not
know the history of most of the
earth's volcanoes.
Clearly, it will be some time before
we can consistently predict eruptions
at most volcanoes, including those in
some of the most heavily populated
areas.
Aspects of Volcanic Science
Giant strides have been made in
our understanding of the dynamics
of the earth's surface and of the be-
havior of rock systems at pressures
and temperatures equivalent to sub-
crustal conditions within the earth.
Yet our knowledge of the basic
physics and mechanisms involved in
volcanic processes are at best sketchy,
our explanations speculative and
largely qualitative, and our predic-
tions based on observed history rather
than fundamental understanding of
the real mechanics involved.
The number of scientists conduct-
ing serious investigations of volcanoes
is fairly small; they are concentrated
in the countries where most of the
earth's 450 active volcanoes are
found — the circum-Pacific belt (New
Zealand, the Philippines, Japan, east-
ern Soviet Union, Alaska, and western
North and South America) and an
east-west region extending from Java
through the Mediterranean. Most of
today's students are Japanese, Ameri-
can, Russian, Italian, Australian, In-
donesian, or Dutch.
Interaction with Man and
Environment
Volcanoes are spectacular in state
of eruption, and their effects on life
and property have often been devas-
tating. Damage is inflicted by several
means: fall of fine-grained ash from
the atmosphere; ash flows; lava flows;
and tidal waves associated with
violent eruptions. The most devas-
tating and dangerous eruptions are
those that produce ash flows or vio-
lent blasts. These are also among the
least understood, because the erup-
tions are short-lived and have not
been well studied.
The United States has over 30
active volcanoes, mostly in Alaska.
(See Figure II-8) Within continental
United States, large dormant vol-
canoes include Mt. Rainier, Mt. Baker,
Mt. St. Helens, Mt. Shasta, and Mt.
Lassen. Phreatic (steam-blast) erup-
tions occurred in Hawaii in 1924; the
hazard grows with population density.
Alteration of the environment near
an erupting volcano can be dramatic.
Some believe the decline of Minoan
civilization on Crete (about 1500 B.C.)
resulted from the eruption of the vol-
cano Thera. More recently, an ash
fall associated with the 1968 eruption
of Cerra Negro, Costa Rica, threat-
ened to choke off San Juan, the capital
city. In the United States, historic
lava flows from Kilauea and Mauna
Loa, on Hawaii, have reached the sea,
burying productive sugar cane fields.
The 1959 flow accompanying an erup-
tion along the east rift zone of Kilauea
buried the town of Kapoho. The 1950
flow from Mauna Loa reached the sea,
endangering for a time the town of
Kailua-Kona on the west side of
Hawaii.
Among the greatest direct threats
to life are eruptions producing ash
flows. A spectacular and devasting
historic eruption of this type occurred
on Martinique in 1902. An ash erup-
tion from Mt. Pelee flowed down the
flank of the mountain at an estimated
50 to 100 miles per hour and buried
the town of St. Pierre, with a loss of
38,000 lives. A passing ship observed
a similar eruption at Mt. Katmai,
Alaska, in 1912; it produced the Val-
ley of Ten Thousand Smokes, but
there was no known loss of life. Such
eruptions could recur nearly any-
where along the Aleutian chain. An
eruption of this type in a populated
region would be a catastrophe.
One of the most dramatic examples
of the effect of volcanic action on the
environment was the eruption of
Krakatoa, in 1883, in eastern Sumatra.
Krakatoa is a large, cauldron-type
volcano. It erupted with an energy
estimated as equivalent to 100 to 150
megatons of TNT. Some 36,000 peo-
ple lost their lives in this eruption and
the tidal wave that accompanied it.
The blast was believed to have been
the result of sea water entering the
magma chamber after a two-week
period of relative quiet. The resulting
acoustic wave produced in the atmos-
phere propagated to the antipodes
44
VOLCANOES
Figure 11-8— U.S. VOLCANOES
CANADA
Mt. SI. Helen
Ml R ji
Mt Hood ," Ml, Adams YX
Mt Jefferson # « / / Columbia River
Crato'lake •** "-' \ p|a'M"
Mt. Shasta t
/
Lassen Peak a
This figure indicates the active volca-
noes of the U.S. as well as Quaternary
volcanoes and other areas of volcanic
activity.
and back eight times as recorded by
microbarographs around the world.
Fine-grained ash was dispersed
throughout the atmosphere and pro-
duced distinctly red sunsets as far
away as Europe.
Long-Term Effects — Volcanoes
may also have an important effect on
man's environment on geologically
long time-scales. Fine-grained air-
borne volcanic material may have a
serious effect on the long-term heat
balance of the earth, for example, by
changing the reflection properties of
the upper atmosphere. The ash from
Krakatoa reduced the incident solar
flux to the surface by about 20 per-
cent of its normal value. Such effects
have been postulated as a possible
contributing cause for continental
glaciation. In this view, glaciations
result from a reduced heat flux to the
earth's suface as a consequence of
fine ash in the atmosphere dispersed
by a higher general level of volcanic
activity.
In addition, most of the gases that
produce the atmospheres and oceans,
the products of outgassing of the
earth's interior, probably reach the
surface through volcanoes. Hence,
the nature of volcanism is intimately
tied to such general questions as the
nature and evolution of planetary
atmospheres.
Ability to Forecast Eruptions
Perhaps the most serious matter is
that of predicting catastrophic and
unexpected eruptions. Volcanic soils
are among the most fertile in the
world; consequently, the slopes of
even active volcanoes are populated
and used for agricultural purposes.
Furthermore, the time between violent
volcanic events varies from several
decades to several thousand years — a
short time geologically but a long time
on the scale of man's life and memory.
There is thus a significant amount of
economic pressure to occupy hazard-
ous places. It is virtually certain that
violent eruptions like those at Kraka-
toa, Vesuvius, or Mt. Pelee will occur
in the future.
Our ability to explain or predict
volcano behavior is poor and restricted
to a few isolated, well-studied ex-
amples. The behavior of Kilauea, on
the island of Hawaii, is one of the
most systematically monitored and
historically well-studied volcanoes in
the world, along with Asama and
Sukurajima in Japan. (In 1914, Su-
kurajima erupted and seven villages
were destroyed; property damage was
some $19 million, as 25 square kilo-
meters were buried under new lava;
no lives were lost.) Kilauea has been
monitored almost continuously since
1912, the year that Jagger estab-
lished the Hawaiian Volcano Obser-
vatory (HVO), operated since 1917 by
the U.S. Geological Survey (USGS).
Integrated geological, geophysical,
and petrological chemical observa-
tions have been made of Kilauea's
eruptions and the lavas produced.
Small-scale earthquakes accompany-
ing upward movement of molten rock
at depth have also been studied.
Swelling of the volcano prior to erup-
tion has been monitored by precise
leveling and strain measurements. All
this has resulted in a basis for erup-
tion prediction based on previous ex-
perience.
The ability to predict eruptions at
Kilauea has little use elsewhere, how-
ever, since each volcano has it own
personality which must be studied to
be understood. Furthermore, Hawai-
ian-type volcanism, while it has been
destructive of property, is the most
passive of all types of eruption. And,
in spite of a long history of observa-
tion and systematic data collection at
Hawaii, we are still basically ignorant
of some important and interesting
facts: details of the melting processes
operative in the earth's mantle that
are responsible for the generation of
the lava; the mechanics of the propa-
gation of fractures in the mantle crust
and the hydrodynamics of transport
of the lava to the surface; the rela-
tionship of the lava to the fragments
of subcrustal (mantle) rocks contained
in some lavas; the nature of the man-
tle underlying Hawaii; and, finally,
why the Hawaiian chain (and the ac-
tive volcanism) is marching south-
eastward across the Pacific.
45
PART II— DYNAMICS OF THE SOLID EARTH
Diversion and Modification
Through Technology
Hilo, the second largest city in the
Hawaiian Islands, lies in the bottom
of a shallow, trough-like valley on the
east flank of Mauna Loa and Kilauea.
By chance, the most voluminous his-
toric flows have occurred on Mauna
Loa's west side and have, therefore,
flowed away from Hilo. In 1938 and
1942, however, lava flows erupted
from the east side of the peak and
proceeded downslope toward Hilo.
The U.S. Army Air Force, acting on
recommendations of geologists from
the HVO, bombed lava tubes in the
upper part of the 1942 flow, success-
fully diverting the flow of hot lava
from the interior of the tubes onto the
surface of the flow and possibly slow-
ing the forward advance of the flow's
leading edge some fifteen miles down
the hill. The flow did not reach Hilo.
The effectiveness of the bombing is a
matter of conjecture, however, since
termination of the extrusion of lava
from Mauna Loa occurred at about
the same time.
While there have been no direct at-
tempts to alter the cycle of activity of
any volcano, a 1.2-megaton atomic
experiment conducted by the Atomic
Energy Commission on October 2,
1969, in Amchitka Island in the Aleu-
tians, may represent — though not by
design — the first such project. Kiska
Volcano, on Kiska Island, erupted on
September 12, about three weeks be-
fore the experiment was to be held
some 500 kilometers away. Had this
eruption occurred three or four weeks
later, a controversy about the possible
cause-and-effect relationships between
the blast and the eruption would un-
doubtedly have ensued. The experi-
ment on Amchitka was preceded by
considerable debate among seismolo-
gists about the possible effects on the
seismicity of that part of this tec-
tonically active island chain. Since
seismicity and volcanism are inti-
mately related on a worldwide basis,
the relevant areas in the Aleutians
should be carefully monitored for pos-
sible alteration of the local volcanic
regimen.
Potential Sources of Basic
Information
It is clear that many disciplines will
contribute to progress in volcanology
— field geology, experimental and
observational petrology, geophysics,
geochemistry, fluid mechanics, and
others. Advances in our knowledge
of volcanic mechanisms can be ex-
pected from detailed observations, ex-
periments, and, eventually, theoretical
(mathematical) models.
Field Observations — Any signifi-
cant advance in our knowledge and
understanding of volcanoes must be
observationally based. Like all geo-
logical processes, the number of pa-
rameters involved and the complexity
of the physical processes are very
great. Eruptions amount to large-scale
and uncontrolled natural experiments.
Meaningful quantitative data can only
be provided by systematic observa-
tions by prepared observers with ade-
quate instruments in the right place at
the right time.
Any really basic, thorough under-
standing of volcano mechanisms, vol-
cano physics, and, eventually, erup-
tion prediction will follow detailed
observational work — both long-term
investigations of individual volcanoes
and ad hoc, short-term investigations
of volcanoes in a state of eruption.
The fruits of such observation can be
seen at Kilauea. Extended study by
the USGS has produced a detailed
geological, physical, and chemical de-
scription of this volcano. Detailed
knowledge of the behavior of Kilauea,
particularly prior to eruption, is
known, and reliable eruption predic-
tion by HVO has become routine. The
Hawaii experience underscores two
important points: (a) The ability to
predict the behavior of specific vol-
canoes is based on experience and
careful observation over a substantial
period of time, (b) Systematic collec-
tion of several types of data (geo-
physical, geological, penological,
chemical) is required.
Laboratory Experiments — There
are a number of laboratory experi-
ments that may yield useful informa-
tion: the chemical evolution of mag-
mas and mineralogical and chemical
evolution with time in relation to
eruption history are important param-
eters to establish. Petrologic and
chemical observation of volcanic prod-
ucts can be closely correlated to the
eruption history of observed (recent)
events or to carefully reconstructed
ones, yielding data about the evolu-
tion of magmas that culminate in
violent terminal activity.
Laboratory investigation of physi-
cal properties of lava and magmatic
systems, especially volatile-bearing
ones, is needed. Little is known about
the physical characteristics of lavas
under dynamic conditions — for ex-
ample, expansion during rise in a vol-
cano from depth. The formation of
volcanic ash and catastrophic erup-
tions are associated with inhibited
vesiculation (bubbling) of lava during
rapid rise to the surface. These erup-
tions are the most destructive, and
they are not well understood.
Experimental petrology (investiga-
tions of rock systems in controlled
situations in high-pressure vessels in
the laboratory) will yield data useful
in the quantitative reconstruction of
specific events as captured in rock
textures and in mineralogical asso-
ciations in volcanic rocks. By com-
parison of laboratory results with ob-
served relationships in volcanic rocks,
much can be inferred about the his-
tory of formation of specific volcanic
rocks that can never be directly ob-
served because the rocks occur too
deep within the volcano.
Simulation Experiments — Some
progress could come from large-scale
simulation of certain volcanic proc-
esses, in much the same way as our
understanding of meteorite-impact
46
VOLCANOLS
physics was greatly aided by high-
yield atomic-explosion experiments.
It might be feasible to simulate cer-
tain aspects of volcanic eruptions on
a rather large scale. Such experiments
would yield useful information on the
interior ballistics problem (flow within
the interior of volcanoes) and also on
the exterior ballistics of volcanic
ejecta, especially ballistics of large
fragments.
Small-scale model simulation of
volcanic processes is an exceedingly
difficult endeavor because of the
necessity to satisfy similitude require-
ments for both heat and mass trans-
fer. However, much has been learned
in a qualitative way about other geo-
logical processes — e.g., convection of
the earth's mantle and motion of
ocean currents — by such experi-
ments. The results, while semi-
quantitative, nonetheless can be quite
informative, especially when closely
tied to field observation. Model meth-
ods could profitably be applied (and
have been to a limited degree) to a
number of volcanic mechanisms, such
as the emplacement of lava and ash
flows.
Mathematical Description — Vol-
canic processes are complex. The
eruption of volcanoes involves the
flow of a fluid system from a high-
pressure reservoir at depth to the sur-
face through a long rough pipe, or
conduit. In this process of fluid flow,
heat and momentum are exchanged
both within the system and with the
vent walls. As the erupting medium
rises, the confining pressure decreases
and a number of things result — ex-
solution and expansion of the vola-
tile phases (gas), and cooling due to
expansion. Near the surface, these
processes are rate-controlled rather
than simple equilibrium ones.
Mathematical description of the
hydrodynamic and heat-transfer prob-
lems are rudimentary. There exists
abundant literature in engineering
and physics, however, which could
be applied readily to a number of vol-
canic processes. For example, in the
last decade our knowledge of the be-
havior of complex multi-phase sys-
tems involving gas, solid, and liquid
phases has advanced because of their
importance in engineering practice
(e.g., to determine the flow in rocket
nozzles). General hydrodynamic
codes for the description of the de-
formation of material under shock
loading have been developed to de-
scribe target effects around explosions
and impacts, and these codes can be
modified to describe volcanic situa-
tions. Further, the flow in gas and oil
wells and reservoirs is probably simi-
lar to the flow in some volcanoes and
their reservoirs. Also, the interaction
of the high-velocity stream of gas and
fragments ejected by an erupting vol-
cano into the atmosphere is a special
case of the interaction of a jet with
fluid at rest. These problems appear
to be ripe and could develop very
swiftly.
The science of petrology has pro-
gressed very rapidly in the last dec-
ade, to the extent that many quantita-
tive estimates can be made regarding
the temperatures and pressures of the
formation of certain minerals and
mineral assemblages found in vol-
canic rocks. These are very important
constraints on mathematical formula-
tion of the eruption problem. But the
greatest single impediment to the for-
mation of mathematical descriptions
of volcanoes in state of eruption is the
lack of systematic, quantitative field
data regarding eruption parameters
(mass flow rate, temperature, veloci-
ties and direction of fragments ejected,
the abundance and chemical composi-
tion of the gas phase, and petrog-
raphy and chemistry of the rocks
produced).
State of Observational
Data and Tools
Present data on active volcanoes
are quite incomplete, although the
means of acquisition of important in-
formation are available. One reason
data are incomplete is that, prior to
modern jet transportation, it was
simply impossible for qualified sci-
entists to arrive at the scene in time
to gather the most interesting infor-
mation, which occurs in the first few
hours or days of activity of many vol-
canic events.
For the past ten years, the Depart-
ment of Defense and National Aero-
nautics and Space Administration
have applied a powerful array of re-
mote-sensing and photographic tech-
niques to the investigation of some
volcanoes. The 1963 eruption of Surt-
sey, in Iceland, was studied, for ex-
ample. These methods hold great
promise and if applied to the study of
eruptions would produce a substantial
increase in the quantity of available
data as well as provide new kinds
of information. Even though means
exist for highly sophisticated and
complete investigations, however, the
number of eruptions that have been
thoroughly exploited is negligibly
small.
The investigation of active vol-
canoes requires cooperation between
fairly small numbers (3 to 10) of well-
qualified professional observers, with
technical support (including commu-
nications, logistics, and transporta-
tion) to be provided at very short
notice. The Smithsonian Institution
has set up a facility to fill part of this
need: The Center for Short-Lived
Phenomena, in Cambridge, Massa-
chusetts. The center serves effectively
as an information source for scientists
covering a number of specialties, in-
cluding volcanology and geophysics.
The center notifies potentially inter-
ested scientists by telephone or wire
of events such as volcanic eruptions;
it then, on very short notice, organizes
teams to visit the sites, ideally within
24 hours. The function of the center
is to dispense information and to
organize logistics for adequately pre-
pared individuals with their own
funding. The number of such scien-
tists is well below the number re-
47
PART II— DYNAMICS OF THE SOLID EARTH
quired to monitor the world's inter-
esting volcanic events, however, and
the results fall far short of what is
possible within the capabilities of
modern transportation and modern
data-gathering methods.
Requirements of Science
We expect advances in our under-
standing of fundamental volcanic
mechanisms to evolve from two broad
types of investigations:
Long-term investigations of in-
dividual volcanoes, volcanic
features, and volcanic fields.
These studies will focus on
the origin of the magmas and
land forms and their evolution
through time. The goal of the
research is to develop the de-
tails of the physical processes
producing these features and
the reasons for their evolution.
Some of this kind of work is in
progress in the United States.
Well-coordinated and short-
term field investigations of vol-
canoes in eruption by teams of
prepared and qualified scien-
tists capable of responding on
very short notice. This is a new
kind of activity, not currently
well organized.
48
PART
CLIMATIC CHANGE
1. CYCLICAL BEHAVIOR OF CLIMATE
Long-Term Temperature Cycles and Their Significance
The earth's climate results from
three fundamental factors:
1. The earth's mass, which pro-
vides a gravitational field of
sufficient strength to hold all
gases released from the interior
except hydrogen and helium;
2. The amount of energy emitted
by the sun, the distance of the
earth from the sun, and the
earth's reflectivity, which com-
bine to provide surface temper-
atures on earth suitable for the
existence of a substantial hydro-
sphere, including oceans, rivers,
lakes, and, at certain times, con-
spicuous ice masses;
3. The astronomical motions of
the earth which, together with
the inclination of the earth's
axis on the plane of the ecliptic,
provide diurnal and seasonal
cycles.
If these three fundamental factors
(and their components) were to re-
main constant through time, the
earth's climate would not change
except for short-range phenomena re-
lated to the hydro-atmosphere. Geo-
logical history and direct human ob-
servation show, however, that climate
has changed and is changing conspic-
uously, with variations ranging from
a few to many millions of years. The
causes for these changes are numer-
ous and varied, and often multiple.
Affecting mankind most, either
favorably or unfavorably, are the
changes that occur across time inter-
vals ranging from tens of years to
50,000 years. The former may en-
courage men to undertake great agri-
cultural and industrial activity in
regions affected by climatic ameliora-
tion, only to have their efforts de-
stroyed when climate deteriorates; the
latter have brought about the great
glacial/interglacial cycles of the past
million years, which strongly affected
the entire biosphere and directed the
course of human evolution.
Short-Range Climatic Change
Short-range climatic variations
(years to centuries) have been moni-
tored by direct observation since the
dawn of recorded history, but accurate
climatic measurements date only from
the middle of the seventeenth century
when the Accademia del Cimento of
Florence and the Royal Society of
London began their works. For more
than a hundred years these observa-
tions were restricted to Europe.
Global climatic cycles for which an
explanation is immediately clear are
the diurnal cycle, due to the rotation
of the earth, and the yearly cycle, due
to the revolution of the earth around
the sun. A 2.2-year cycle due to alter-
nating easterlies and westerlies in the
equatorial stratosphere also appears
rather well established. If the effect
of the daily, seasonal, and yearly
cycles is eliminated, climatic records
— including temperatures, pressure,
precipitation, wind strength, and
storm occurrences — may also exhibit
apparent periodicities. Thus, in 1964
Schove listed a dozen possible cycles,
which ranged in wavelength from 2
to 200 years. An apparent 20-year
periodicity, for instance, is shown by
the 10-year moving average tempera-
ture record for July in Lancashire,
England. A similar periodicity is not
visible, however, in the temperature
record for January. The problem is
that an infinite record would be neces-
sary in order to prove that a cyclical
phenomenon is really stationary —
i.e., that conditions at the end of a
cycle are identical to those at the
beginning.
Figure 111-1 — AVERAGE WATER LEVEL IN LAKE VICTORIA
This graph indicates that the rise and fall of water level in Lake Victoria from 1900
to the middle of the 1920's was correlated with the 11-year sunspot cycle. After
that period, however, the correlation broke down.
51
PART III — CLIMATIC CHANGE
The Role of Solar Activity — An
example of the erroneous conclusions
to which inadequate analysis of cycli-
cal phenomena may lead is shown in
Figure III-l. A relationship between
sunspots and water level in Lake Vic-
toria may be inferred from the record
between 1900 and 1925, but this rela-
tionship breaks down completely after
1925. As a matter of fact, the search
for causal relationship between cli-
mate and the solar sunspot cycle,
which averages 11.2 years but ranges
from 8 to 18 years, has proved rather
unsuccessful. A climatic effect prob-
ably does exist, but it is small and
masked by other phenomena.
Changes in solar activity may in-
duce changes up to a factor of a
thousand in the short wavelength re-
gion of the solar spectrum, but this
region represents only a hundred-
thousandth of the total energy emit-
ted by the sun. Thus, the change in
solar energy output produced by vari-
ations in solar activity is at most one
percent. Work by the Smithsonian
Institution has shown, however, that
the amount of solar energy received
at the outer boundary of the earth's
atmosphere at the mean distance from
the sun (the so-called "solar con-
stant," equal to 1.3 million ergs per
square centimeter per second) has re-
mained constant within the limits of
error of the observations during the
past 50 years.
Examples From the Past — Secular
climatic changes are often impressive.
For example, Lake Constance froze
completely in the winter of 1962-63
for the first time since 1829-30; Lake
Chad poured water into the Sahara in
1959 for the first time in 80 years;
precipitation in northeast Brazil has
decreased 50 percent during the past
50 years; arctic temperatures rose
some 2° centigrade between 1885 and
1940; and the average temperature of
the atmosphere and ocean surfaces
increased 0.7° centigrade during the
same time. Some of these changes are
regional (i.e., temperature rises in one
region while decreasing in an adja-
cent one), but others, including the
latter one just mentioned, are not.
Global climatic changes ranging
across time intervals of decades to
many centuries are known from his-
torical records and geological or pale-
ontological observations. Exception-
ally good weather prevailed in Europe
between a.d. 800 and 1200, when
glacier boundaries were about 200
meters higher, when the Vikings sailed
across the northern seas, and when
Greenland received its name. A few
centuries of colder climate followed:
the Baltic froze solid in the winter of
1322-23, an event that has not been
repeated since; Iceland was blocked
by ice for six months of the year dur-
ing the first half of the seventeenth
century (compared to 1-3 weeks
today); and all Alpine glaciers read-
vanced substantially in the same
period. Since the beginning of the
nineteenth century, climate has im-
proved again. Whether these climatic
changes are cyclical or not is not
known, although "cycles" of 80 and
200 years, presumably induced by
solar changes, have been mentioned
in the literature.
Long-Range Climatic Change
Climatic changes across longer time
intervals (a few thousand years to
millions of years) can only be inferred
from the geological and paleontologi-
cal records. The occurrence of mod-
ern-looking blue-green algae in chert
deposits dating from two billion years
ago indicates that the radiation bal-
ance of the earth has not changed
much over this extremely long time
interval. However, three times since
the beginning of the Cambrian era,
about 600 million years ago, the radia-
tion balance of the earth has been
sufficiently disturbed to produce con-
spicuous glaciations. This happened
during the Early Paleozoic (about 450
million years ago) , Late Paleozoic
(about 250 million years ago), and
Late Cenozoic (the past few million
years). At these times, ice-sheets
some 2 kilometers thick repeatedly
covered as much as 30 percent of the
continental surface.
Why Glaciation Occurs — For these
major glaciations to develop, the radi-
ation balance of the earth must have
become negative with respect to its
normal state during nonglacial times.
That is, the amount of solar radiation
reflected back into outer space must
have become greater. Cooling of the
earth by a decrease of incoming solar
radiation does not seem likely be-
cause, according to the 1953 calcu-
lations of Opik, formation of the ice-
sheets to the extent known would
have entailed cooling the equatorial
belt down to 8 centigrade, whereas
the paleontological record indicates
that warm-water faunas have existed
ever since the beginning of the Cam-
brian. Therefore, the radiative bal-
ance of the earth must have become
negative through the effect of terres-
trial phenomena alone.
Many such phenomena could have
done the trick. For instance, an in-
crease in continentality would have
increased the earth's reflectivity and
produced cooling, since land absorbs
less solar energy than the sea. Dis-
placement of continental masses to-
ward high latitudes should favor
glaciation. Finally, an increase in
atmospheric haze produced by vol-
canic activity and dust storms could
have reduced the amount of solar
energy reaching the earth's surface
and, at the same time, reflected into
space a portion of the incoming solar
radiation. Once the earth's surface
temperature is reduced below a certain
critical value by one or another or a
combination of these factors, ice may
begin to develop. Ice is highly reflec-
tive, of course, so that more ice means
more solar energy reflected, lower
temperatures, and even more ice. In-
deed, ice appears to be self-expanding
and to come to a stop only when the
ocean has cooled so much as to pro-
vide insufficient evaporation for feed-
ing the ice-sheets.
The pattern of glaciation is best
known for the past few hundred thou-
52
CYCLICAL BEHAVIOR OF CLIMATE
sand years, a time during which ice-
sheets repeatedly formed and ad-
vanced to cover North America as far
south as a front running from Seattle
to New York, and Europe as far south
as a front running from London to
east of Moscow. A substantial ice-
sheet also repeatedly covered Pata-
gonia, and mountain glaciers formed
wherever high mountains and moun-
tain ranges were available. The re-
peated advances of the ice-sheets were
separated by interglacial times during
which all continental ice-sheets dis-
appeared except those of Greenland
and Antarctica. We are presently in
the middle of one of these interglacial
times.
The advances and retreats of con-
tinental ice have left the glaciated
lands littered with glacial debris,
ranging in size from fine sand and
clays to boulders as large as a house.
From the study of these sediments,
geologists have concluded that the
ice-sheets formed and swept across
the northern continents at least five
times during the recent past. The
sediments are so mangled, however,
that it is difficult to reconstruct a
complete history of the glacial events.
"Globigerina Ooze" — For a more
complete record one must turn to
the deep sea. About 40 percent of
the deep ocean floor is covered with
a sediment known as "Globigerina.
ooze." This sediment is rich with the
empty shells of planktonic Foramini-
fera, microscopic protozoans freely
floating near the surface when alive.
Of the fifteen common species of
planktonic Foraminifera, several are
restricted to equatorial and tropical
waters, several to temperate waters,
and one to polar waters. When cli-
mate changes, the foraminiferal spe-
cies move north or south, and these
movements are recorded in the sedi-
ment on the ocean floor by alter-
nating layers of empty shells belong-
ing to warm, temperate, and cold
species. Sediment core samples up to
20 meters long have been recovered.
Paleontological analysis of the chang-
ing foraminiferal faunas through these
cores reveals the climatic changes that
occurred while the sediment was being
deposited. In addition, it is known
that foraminiferal shells formed dur-
ing cold intervals contain a greater
amount of the rare oxygen isotope 1S O
than shells formed during warm in-
tervals. Thus, oxygen isotopic analy-
sis of the foraminiferal shells yields
accurate information on the actual
temperature of the ocean surface and
its variations through time. The re-
sults given by micropaleontological
and isotopic analysis are essentially
identical.
Because Globigerina ooze accumu-
lates at the rate of a few centimeters
per thousand years, a deep-sea core
20 meters long reaches sediments half
a million years old. Deep-sea cores
can be dated by various radioactive
methods, including radiocarbon and
the ratio of thorium-230 to protac-
tinium-231. Thus, climatic changes
can not only be followed in continuity
by studying deep-sea sediments but
can also be dated.
The study of many deep-sea cores
from the Atlantic and the Caribbean
has made it possible to reconstruct a
continuous curve showing the tem-
perature changes of the surface ocean
water at low latitudes over the past
425,000 years. This curve, shown in
Figure III-2, exhibits a number of
alternating high- and low-temperature
intervals, with a gross periodicity of
about 40,000 years. A comparison of
this curve with the chronology of con-
tinental glaciation, based largely on
radiocarbon dating, shows that the
most recent low-temperature interval
(70,000 to 15,000 years ago) repre-
sents the last major glaciation. One
may safely infer that earlier low-
temperature intervals of the oceanic
curve represent earlier continental
glaciations.
Sediments older than the oldest
ones represented in Figure III-2 have
been recovered recently from the
ocean floor by the drilling vessel
Clomar Challenger; analysis of these
sediments, yet to be performed,
should show how far back in the
past temperature variations as large
as those of Figure III-2 continue.
For the time being, sections of older
marine sediments now occurring on
land have been used. One of these
sections, representing sediment de-
posited about 1.8 million years ago in
southern Italy, shows that climatic
variations as large as the most recent
ones were already occurring at that
time.
The General Temperature Curve —
The apparent periodicity of 40,000
years is intriguing. No terrestrial
phenomenon of the type described
before is believed to take place with
Figure 111-2 — CHANGES IN THE TEMPERATURE OF THE OCEAN SURFACE
Changes in the ocean surface temperature over the past 425,000 years have been
reconstructed from deep-sea cores. Present time is at the left of the graph. The
numbers above the time axis are for reference, indicating the peak of the long-term
cycles.
53
PART III — CLIMATIC CHANGE
such periodicity. These terrestrial
phenomena last either much shorter
times, like volcanic eruptions or dust
storms, or much longer times, like
changes in the relative position or
extent of continents and oceans.
There are, however, certain astronom-
ical motions of the earth that occur in
cycles of tens of thousands of years.
Because of the attraction of the moon,
the sun, and the planets on the bulge
of the earth, the earth's axis precesses
with a periodicity of 26,000 years; the
obliquity of the ecliptic with respect
to the terrestrial equatorial plane
changes with a periodicity of 40,000
years; and the eccentricity of the
earth's orbit changes with a periodic-
ity of 92,000 years. The result of
these motions is that, in the high
latitudes, periods of warm summers
and cold winters alternate every
40,000 years with periods during
which summers are colder and winters
warmer.
Long before research on deep-sea
sediments indicated the probable oc-
currence of climatic cycles 40,000
years long, the Serbian physicist Mi-
lankovitch and the German meteor-
ologist Kcippen had suggested that
long periods of cool summers could
trigger a glaciation even if accom-
panied by warmer winters. They
reasoned that winter is cold enough
anyway at high latitudes for snow to
accumulate on the ground, while cool
summers would allow permanent
snow to expand year after year. The
earth's reflectivity would thus in-
crease, temperature would decrease,
more snow would accumulate, and a
major glaciation would rapidly de-
velop.
This theory was enlarged by Geiss
and Emiliani to include plastic ice-
flow, heat absorption by ice-melting,
and downbuckling of the earth's
crust under the weight of the ice-
sheets in order to explain the disap-
pearance of the major ice-sheets
(Greenland and Antarctica excluded)
at the end of each glaciation. As it
now stands, the theory seems to ac-
count for glacial and interglacial
events and their time-scale during the
recent past. It also accounts for the
timing of high interglacial sea levels
related to ice melting. That is, the
times when summers were warmest,
as calculated from astronomical con-
stants, were also the times when sea
level stood high as determined by
radioactive dating of fossil shells and
corals.
The generalized temperature curve
of Figure 1II-2 shows, superimposed
on the major oscillations, a number
of smaller oscillations. Mathematical
analysis of the original isotopic curves
of the deep-sea cores has shown
that these smaller oscillations are re-
lated to the precession of the equi-
noxes. Precession of the equinoxes is
apparently also responsible for the
occurrence of more than one high sea
level during interglacial intervals, oc-
curring whenever northern summers
coincide with perihelion and resulting
from partial or even total melting of
Greenland ice.
Figure III-3 shows the original oxy-
gen isotopic curves for two deep-sea
cores from the Caribbean. The hori-
zontal scale shows the depth below
the top of the core, the tops of the
cores being on the left side (0 cm).
The tops represent modern sediments,
and the time-scale for the various
cores can be evaluated by comparing
each curve with the generalized tem-
perature curve of Figure III-2. The
vertical axis represents the 180/u'0
concentrations, which are inversely
proportional to temperature. The
more negative values, therefore, rep-
resent higher temperatures.
As shown in Figure III-3, isotopic
values as negative as the ones occur-
ring at the tops of the cores, repre-
senting the present interglacial con-
ditions, occur only occasionally below.
Temperature was considerably lower
than today during much of the previ-
ous interglacial intervals, with periods
of temperatures as high as today oc-
curring only for a short time (a few
thousand years at most) at the peaks
of the previous interglacial ages. The
present period of high temperature
began about 8,000 years ago and
reached a peak 2,000 years later. It
was followed by a 2°-centigrade tem-
perature decrease about 4,000 years
ago, in turn followed by a l°-centi-
grade increase.
The Present Situation
All these changes, short-term as
well as long-term, regional as well as
Figure 111-3 — TEMPERATURE CURVES DERIVED FROM OXYGEN
ISOTOPE RATIOS OF DEEP-SEA CORES
400
500 600 700 800 900
DEPTH BELOW TOP (cm)
1000 1100 1200 1300 1400
Sediments formed from shells of microscopic protozoans are known to have a high
concentration of '~0 when formed during cold periods. Therefore, high values of
the ratio ls0/"O indicate cool temperatures; low values indicate warm temperatures.
The point at which the core is sampled can be dated by other means. Several
centimeters of core represent a thousand years.
54
CYCLICAL BEHAVIOR OF CLIMATE
global, must be carefully monitored
and studied. Because the environ-
mental balance is delicate, and be-
cause it can be affected not only by
natural changes but also by man-
made ones, a thorough understand-
ing of climatic history and dynamics
is important indeed. Furthermore,
many climatic events appear to result
from triggering actions involving only
a small amount of energy. An under-
standing of these actions is important
not only to prevent catastrophic cli-
matic changes (as, for instance, the
development of new glaciation or the
melting in part or in whole of the ice-
caps of Greenland and Antarctica)
but also to develop methods for cli-
matic control.
Judging from the record of the past
interglacial ages, the present time of
high temperatures should be drawing
to an end, to be followed by a long
period of considerably colder temper-
atures leading into the next glacial
age some 20,000 years from now.
However, it is possible, or even likely,
that human interference has already
altered the environment so much that
the climatic pattern of the near future
will follow a different path. For in-
stance, widespread deforestation in
recent centuries, especially in Europe
and North America, together with in-
creased atmospheric opacity due to
man-made dust storms and industrial
wastes, should have increased the
earth's reflectivity. At the same time,
increasing concentration of industrial
carbon dioxide in the atmosphere
should lead to a temperature increase
by absorption of infrared radiation
from the earth's surface. When these
human factors are added to such
other natural factors as volcanic erup-
tions, changes in solar activity, and
resonances within the hydro-atmos-
phere, their effect can only be esti-
mated in terms of direction, not of
amount.
Long-Term Temperature Change —
Because climatic changes across in-
tervals of years to centuries are so
much affected by the time-character-
istics of our turbulent hydro-atmos-
phere, no immediate breakthroughs
are to be expected toward a global
view of climatic dynamics across
these intervals. Much progress has
been made, however, in the study of
climatic changes across longer time
intervals, in which the intractable
turbulent effects cancel out. Studies
already under way concern: the am-
plitude of the glacial/interglacial tem-
perature change at different latitudes
and in oceans other than the Atlantic,
using oxygen-isotopic analysis of suit-
able deep-sea cores; short-range
(years to centuries) climatic changes
through oxygen-isotopic analysis of
deep-sea cores for anaerobic basins;
and climatic change in the absence of
ice on earth using deep-sea cores of
Middle and Early Cenozoic and of
Late Mesozoic age obtained by the
D. V. Glamor Challenger.
Prospects for Controlling Change
— Judging from past results, the cur-
rent and planned research should con-
tribute importantly to our under-
standing of many climatic problems
related to the evolution of man's en-
vironment and to the possibilities for
altering or controlling it. Research
conducted so far, for instance, has
made much clearer the significance of
the earth's reflectivity as a major cli-
matic factor. If reflectivity is indeed
so important, then control of today's
earth reflectivity by plastic films or
other means may be a way to control
the climatic deterioration already
under way. Again, because glaciation
is essentially a runaway phenomenon,
early control should be much easier
than later attempts at modifying an
already established adverse situation.
Fluctuations in Climate Over Periods of Less Than 200 Years
Factors thought to be responsible
for climatic fluctuations of less than
200 years' duration (and the sciences
involved) are:
1. Short-term fluctuations in solar
radiation (solar and atmospheric
physics) — There is no evidence
of changes in the solar constant
greater than 0.2 percent, al-
though variations do occur in
the particle (X-ray) flux and
also, it is thought, in the ultra-
violet bands shorter than 0.2
microns.
Correlations have been estab-
lished between ultraviolet flux
and stratospheric ozone concen-
trations, but the exact nature of
the links between ozone and the
intensity of the stratospheric
circulation, and the conse-
quences for the troposphere re-
gime, are uncertain.
2. Changes in atmospheric constit-
uents (meteorology, atmos-
pheric chemistry) — Carbon di-
oxide (CO2) is a major absorber
of infrared radiation from the
earth, whereas aerosols (espe-
cially dust) affect solar radiation
by scattering and absorption.
The ratio of absorption to scat-
tering is about 5/3 for urban
sites and 1/5 for prairie and
desert areas.
The nearly global rise of tem-
perature in the first forty years
of this century (see Figure III-4)
has been attributed to increas-
ing CO2 content, although this
is by no means an accepted
theory. The magnitude of the
55
PART III — CLIMATIC CHANGE
Figure III -4 — VARIATION OF THE MEAN ANNUAL TEMPERATURE
OF THE NORTHERN HEMISPHERE
The graph shows the variation of mean annual temperature near the surface of the
northern hemisphere during the past century. Variations in the world mean annual
temperature are similar. The curve is based on data from several hundred stations,
weighted for the area represented by each station. The data are expressed in
terms of ten-year overlapping means of the departures from the 1885 90 mean.
effect for a given increase in
COi concentration is still in dis-
pute. (A 1 -centigrade increase
might require an increase in
concentration of from as little
as 25 percent to as much as 80
percent; at present rates of COj
increase, such a temperature in-
crease would take between 50
and 300 years.)
Little is known about the ef-
fects of volcanic and man-made
dust. The net effect of major
eruptions, such as that of Mt.
Agung in 1963, on total solar
radiation received amounted to
a decrease of only 6 percent.
Turbidity measurements indi-
cate a widespread increase in
atmospheric dust content in this
century, but the role of man in
this, and its meteorological con-
sequences, are largely unknown.
3. Air-sea interaction (meteorol-
ogy, oceanography) — Changes
of ocean surface temperatures
appear to lag two to three years
behind long-term atmospheric
trends, but feedback effects —
by which oceanic processes re-
inforce an initial atmospheric
trend — are of great impor-
tance. Short-lived anomalies
such as the dry summers in
northeastern United States dur-
ing the early 1960's can be
attributed to persistent sea-
temperature anomalies. Little
is known about the factors de-
termining the duration of a
trend or its eventual reversal.
4. Inherent variability in the at-
mospheric circulation (meteor-
ology, fluid dynamics) — The
year-to-year patterns of devel-
opment of the seasonal weather
regimes seem to be essentially
random. Thus, individual ex-
treme seasons may occur in
spite of a general trend in the
opposite direction. Instances
are the severe English winters
of 1739-40 and 1878-79, both
of which followed a series of
mild winter seasons. An exten-
sive snow cover or sea-tem-
perature anomaly may help to
trigger circulation changes if
other conditions are suitable.
On the 50- to 200-year time-scale,
changes in the disposition of the
wind-flow patterns between 10,000
and 30,000 feet are important. There
is evidence of an approximately 200-
year fluctuation in the northern hem-
isphere westerlies, with peaks in the
early 1300's, 1500's, 1700's, and
1900's and with shorter, less regular
fluctuations superimposed. Weaken-
ing of the westerlies in recent decades
has been accompanied by an equator-
ward shift of the wind belts.
Finally, and most fundamentally,
the extent to which global climate
is precisely determined by the gov-
erning physical laws is unknown.
Theoretical formulations indicate the
possibility that all changes in the
atmospheric circulation need not be
attributable to specific causes. That
is, the atmosphere may not be a
completely deterministic system.
Although much recent attention has
been given to changes in atmospheric
constituents, it is not yet possible to
be at all positive as to which, if any,
of these four groups of factors are
the major determinants of relatively
short-term climatic fluctuations —
i.e., those of less than 200 years' dura-
tion. Even the secular changes in the
strength of the wind belts and their
latitudinal location, noted in (4)
above, may be determined by forcing
of extraterrestrial or terrestrial origin.
Characteristics of the Fluctuations
The amplitude of 100- to 200-year
fluctuations of temperature is esti-
mated to be of the order of 1J centi-
grade; decadal averages of winter
temperature have a range of 2 centi-
grade. It is generally accepted that
the longer the duration of a climatic
fluctuation, the larger is the area
affected in any given sense and the
greater is the response of vegetation,
glaciers, and other "indicators." Thus,
over the time period from the mid-
56
CYCLICAL BEHAV!
nineteenth century to the present, the
amplitude and incidence of tem-
perature fluctuations in Europe and
eastern North America are broadly
similar. But certain of the minor
fluctuations lasting perhaps 25 to 30
years are missing, or of opposite
direction, in some localities in these
areas. Minor fluctuations within
North America itself also show spatial
and temporal irregularities.
There is no clear evidence that any
of the fluctuations are strictly peri-
odic — i.e., that they are rhythms.
Around the North Atlantic, the ampli-
tude of the fluctuations over the past
300 years or so appears to have in-
creased while their duration has de-
creased by comparison to the previous
centuries. Periods of about 23, 45-60,
100, and 170 years have been sug-
gested, but not statistically estab-
lished, from observational data and
indirect historical records in Europe.
Recent analyses of cores from the
Greenland ice-cap also indicate fluctu-
ations in lsO (oxygen-isotope) con-
tents with a period of about 120 years.
The spatial pattern of climatic
change during this century is com-
plex. Annual and winter tempera-
tures increased over much of the
globe from approximately 1890 to
1940, especially in high latitudes of
the northern hemisphere; net cooling
has occurred over about 80 percent
of the globe since the latter date.
There is virtually no correlation be-
tween the over-all global changes and
trends in particular areas, which
strongly suggests that the controls
of regional fluctuations are distinct
from those for global changes.
In low latitudes, the most impor-
tant fluctuations involve precipitation,
with a decrease of the order of 30
percent in many parts of the tropics
around 1900. During most of the first
half of this century, the equatorial
rain belt tended to be narrower, and
the tropical arid zone wider, than
either during the preceding half-
century or since the 1940/50's. This
change did not affect monsoon Asia,
but the same pattern of change oc-
curred on the east coasts of Australia
and North America up to about 40
latitude. The other major area affected
by precipitation change is central
Asia, where the 1950/60's have been
much drier.
Interactions with Society
Fluctuations in climate — either nat-
ural or man-induced — can have im-
portant economic and social implica-
tions for man. For example, studies
in England and the eastern United
States since about 1940 indicate a
return to conditions of the early nine-
teenth century. What would be the
implications of such a sustained de-
terioration of climate in the middle
and high latitudes of the northern
hemisphere? What would be the
effects of man's intentional or acci-
dental modification of large-scale and
local climate?
Effects of Continuing Deterioration
— Even beyond such frost-suscepti-
ble, high-value crops as the Florida
citrus fruits, farming activities can be
markedly affected by changes in tem-
perature and moisture balance, espe-
cially those occurring in spring and
fall. The growing season in England,
for example, has shortened by an
average of two weeks since 1950, as
compared with the years 1920 to
1940. Cereal cultivation was revived
in Iceland only in the 1920's, after
a gap of four centuries or more. Many
more summers like that of 1969 —
when sea-ice persisted along the
northern coast for most of the sum-
mer and grain harvests were ruined —
could seriously threaten that coun-
try's marginal economy. The effect
on the fishing industry of Iceland
(and other European countries) could
also be serious.
The increased frequency of severe
winters in northwest Europe since
1939-40, as compared with the pre-
ceding twenty years, has been re-
flected in greater disruption ol
port and increased requirements ior
domestic heating, winter fodder for
cattle, and the like. Through a series
of chain reactions, for example, the
winter of 1^69-70 had a serious effect
on the whole East German economy.
The relationships between climatic
changes and farming are generally
nonlinear. In view of the second-
er third-order interactions among
weather, pests and diseases, soil, and
crops, the implications of recent
changes may be more significant agri-
culturally than the basic climatic fluc-
tuations might suggest. This is as true
in temperate middle latitudes as it is
in semi-arid or other marginal cli-
mates. For example, lower air and sea
temperatures in spring in northeastern
North America are believed to have
affected fish (especially salmon) by
accentuating the sublethal effects of
DDT.
Effect of Man's Activities — Non-
meteorologists tend to base estimates
on assumptions of a constant mean
and variance of the climatic elements.
But there is a serious need to scruti-
nize long-term weather/climate modi-
fication schemes with respect to their
possible interaction with climatic
trends. Cloud-seeding programs de-
signed to augment snowfall in moun-
tain areas, for example, may increase
avalanche hazard and spring-summer
runoff. If the planned increase coin-
cides with an unrecognized trend to
greater precipitation (or falling tem-
peratures), the effects may exceed
expectations.
Unintentional effects of man,
through increased atmospheric pollu-
tion (dust, carbon dioxide and other
gases, supersonic aircraft trails in the
stratosphere), are of international
concern, particularly with respect to
their health implications. The possi-
ble broader effects on global climate
and, directly or indirectly, on man's
economic activities may be even more
critical. Although the role of CO2 is
reasonably well understood, the effect
57
PART III — CLIMATIC CHANGE
of dust on solar and terrestrial radia-
tion is virtually unknown.
In an historical context, it has been
suggested that the Rajasthan Desert
of northwest India may have origi-
nated largely through overgrazing,
with the resultant increase in atmos-
pheric dust content leading to condi-
tions that further decreased rainfall.
Correct identification of natural and
man-made tendencies is vital in such
instances if attempts are to be made
to reverse the processes.
Evaluation of Current Status
Data — The data base available for
the study of climatic fluctuations last-
ing less than 200 years is limited in
a number of respects:
Spatial coverage of climatic data
covering approximately the last cen-
tury and a half is restricted. Direct
observations are particularly limited
for the southern hemisphere gener-
ally, the oceans, the high arctic,
mountain areas in general, and parts
of the tropics. Fortunately, more ex-
tensive records are available for the
European-North Atlantic sector, the
area where climatic fluctuations have
been pronounced.
Climatic data available for a sub-
stantial length of time is restricted to
only a few categories, however —
mainly temperature, precipitation, and
pressure. Indices of volcanic activity
and dust since the late seventeenth
century are available. But records of
solar radiation, atmospheric CO-, and
other dust content, for example, exist
only for shorter periods and provide
a more restricted spatial coverage.
Reconstruction of changes over the
past two centuries is now possible,
using (a) snow/ice cores from Green-
land and Antarctica, which provide
records of O18 changes with good
time-resolution over thousands of
years, and (b) tree-ring indices in
selected areas — the arid margins
for moisture changes and the arctic
(or alpine) margins for temperature
changes. Other techniques for recon-
structing past climates do not allow
the necessary degree of time-resolu-
tion, mainly because of inherent limi-
tations in available dating methods.
Data on the extraterrestrial and ter-
restrial variables that may cause fluc-
tuations are even more limited. Car-
bon dioxide, for example, has been
measured in a few places over the
past 100 years but regular monitoring
is very recent. The monitoring of tur-
bidity has only just begun in a limited
way, and extensive and reliable meas-
urements are similarly available for
only about a decade. Fluctuations in
solar radiation will only be deter-
mined from satellite data, although
there are several centuries of sunspot
records.
Changes in other terrestrial vari-
ables such as sea-surface tempera-
tures, extent of snow cover, pack-ice
and frozen ground, cloudiness, and
total atmospheric vapor content can-
not be assessed with sufficient accu-
racy from available (or foreseeable)
ground networks. Satellite monitor-
ing will again be indispensable.
The fact that "artificial" climatic-
changes due to man's activities mav
obscure, or accentuate, natural trends
further complicates efforts to study
climatic changes over the past 200
years.
Theoretical Formulations — The
development of operative numerical
models of the atmosphere and oceans
which account for the major observed
features of global climate represents
a significant recent advance. Theoret-
ical formulations are generally avail-
able as far as atmospheric-circulation
models are concerned, although theo-
ries of "almost intransitive" systems
need further development. Tidal phe-
nomena in the atmosphere have been
a subject of much recent study, but
their possible implications for climatic
fluctuations have not yet been estab-
lished. Some phenomena — e.g., the
scattering/absorption properties of
aerosols; interactions between strato-
spheric ozone and the general circula-
tion — still present important theo-
retical problems.
Interactions — The possible impact
of climatic fluctuations on man's
activities — agriculture, fisheries, do-
mestic heating, transportation, con-
struction industries, and so on —
appears to have been generally neg-
lected, particularly in terms of mod-
eling and long-range planning. Eco-
system studies of the International
Biological Program will provide some
information pertinent to these prob-
lems, but the difficulty with all short-
term programs of this type is that
climate tends to be regarded as an
environmental constant.
Some Controversial Topics — Con-
cerning the stability of the arctic
pack-ice, would it re-form under pres-
ent climatic conditions if attempts
were made to remove it? Data short-
comings for this area and the problem
of ocean and atmospheric advection
of heat have prevented resolution of
this question.
It has been argued that the appar-
ent recent increase of atmospheric
turbidity may account for the down-
turn of temperature since about 1940.
If this were to be confirmed, a contin-
ued deterioration could be expected,
other things remaining constant.
The problem of changes induced by
turbidity is related to the more gen-
eral, and equally important, problem
of distinguishing between "natural"
and man-induced climatic change.
This is especially significant in assess-
ing the actual and potential effects
of large-scale, long-term weather/
climate modification programs.
Instrumentation — The technical
aspects of required instruments are,
in general, adequately covered. With
respect to determinations of atmos-
pheric turbidity, however, the ap-
plication of LIDAR (light detection
58
CYCLICAL BEHAVIOR C
and ranging) needs further evaluation
and refinement. Similarly, routine
availability for grid-points of all data
collected by satellites is essential for
maximum climatological use of the
information.
Adequate deployment (including
long-term satellite coverage) presents
the major problem. The number of
long-term "benchmark" stations for
measuring the variables referred to
earlier, in addition to the climatic
parameters, is inadequate for many
regions of the globe.
Requirements for Scientific
Activity
The present climatic fluctuation
may be of immediate economic signifi-
cance for areas with marginal climate,
especially in high latitudes. Over the
longer term, possible changes else-
where could be of major importance
for the planning of agricultural pro-
duction, architectural design, heating
requirements, and transportation sys-
tems. It may not be possible to fore-
cast climatic fluctuations with anv
confidence for a decade or more, if at
all, but any planning should incorpo-
rate the best advice of climatologists.
Data Collection — Continued and
intensified monitoring of atmospheric
dust content, especially in mid-ocean
and high-elevation sites, is needed.
Satellite monitoring of global cloudi-
ness, snow and ice cover, atmospheric
vapor content, and sea-surface tem-
perature, with routine data reduction,
is also required.
Data collection needs to be planned
to continue on a long-term basis,
through such programs as the Global
Atmospheric Research Program and
the World Weather Watch. The per-
spective must certainly be global. (In
this connection, it is worth noting that
in much of tropical Africa basic data
networks are now seriously reduced
below what they were in the colonial
era, and this will greatly restrict
future analyses.) Planning for data
collection is urgent within the next
year or two. It cannot be stressed
too strongly that studies of climatic
change require a long series of
records.
Data Analysis — Exhaustive analy-
sis of all available historical weather
information, especially outside Eu-
rope, is needed to provide perspective
on the recent period. Historians
could contribute significantly here.
The reliability of the data must be
assessed and it must be stored in a
form suitable for application of mod-
ern retrieval systems.
Collection and synthesis of all
available "historical" information may
take twenty years. It will, however,
provide essential information for con-
tinued development of theory and
prediction, and it should serve as a
considerable stimulus to interdisci-
plinary work and exchange of ideas
in the fields that are concerned with,
or affected by, climatic change and
its implications.
Dendroclimatic and snow/ice core
studies should be extended to supple-
ment direct records. Dendroclimato-
logical work in the tropics (Africa
and South America), especially near
the alpine timberline, is particularly
needed.
Further study is needed of the mag-
nitude and spatial extent of fluctua-
tions for different climatic parameters,
and of rates of change. These might
offer confirmation, or otherwise, of
the existence of various rhythms.
Advances in general atmospheric-
circulation studies over the next dec-
ade should greatly improve our
understanding of the way in which
the atmosphere responds to internal
and external forcing functions. If
the present climatic deterioration in
middle and high latitudes of the
northern hemisphere is part of a 50-
to 100-year fluctuation, research over
the next decade would be critical in
terms of our "engineering" ability to
cope with it adequately.
Finally, analyses of air-sea feedback
effects on various time-scales need to
be undertaken.
Numerical Model Experiments —
Model experiments should provide
definitive information on the effect
of such variables as pack-ice extent,
snow cover, and sea-temperature
anomalies on the heat budget and on
atmospheric circulation patterns. Ade-
quate sophistication will probably be
available for this work within two to
five years.
Work in progress should provide
information on tropical-temperature
and trans-equatorial links in the gen-
eral circulation necessary to an under-
standing of spatial aspects of fluctua-
tions. It is not yet clear, however,
whether or not this work will clarify
understanding of the way in which
seasonal weather patterns commonly
develop in different manners in differ-
ent years. This is fundamental to the
possibilities of predicting short- or
long-term fluctuations.
Environmental Cyclic Behavior: The Evidence of Tree Rings and Pollen Profiles
One of the major problems to be
faced before we can arrive at an un-
derstanding of environmental cyclic
behavior is concerned with standard-
izing definitions. Attempts at world-
wide standardization of terms in cli-
matic studies are being made. The
Commission for Climatology of the
World Meteorological Organization
has published two suggested glossa-
ries, one for various statistical charac-
teristics of climatic change and the
59
PART III — CLIMATIC CHANGE
other for differentiating between the
various time-scales of climatic change.
Similar glossaries are needed for other
aspects of the physical matrix making
up the environment.
"Operational" definitions are used
here. "Environment" is considered to
be the physical matrix in which orga-
nized and unorganized matter exists.
The term "cycle" refers to the com-
plete course of events or phenomena
that recur regularly in the same se-
quence and return to the original
state; in this sense, a cycle has a true
harmonic course. "Cyclic" (or "cycle-
like") refers to something that only
roughly approximates a harmonic.
Aside from "seasonal" patterns, no
true harmonic behavior has been
found in global or regional climatic
patterns; the latter are cyclic patterns
but they vary in duration and inten-
sity. Several biological and natural
processes reach such a degree of
harmonics that they are sometimes
called rhythms, but these rhythms are
generally tied to seasonal climatic
changes.
Tree growth and pollen production
are, in a certain sense, a physiological
response to the climatic conditions
prevailing at the time these processes
occurred. A thorough understanding
of these processes leads to a better
understanding of the immediate envi-
ronment, and when old samples of
tree rings (the long chronologies) and
pollen production (the pollen profiles)
can be located and studied, past local
environmental conditions can be de-
termined for those specific areas. Pub-
lications are now appearing on cli-
matic conditions over the past 15,000
years or so, as interpreted by various
authors. Although cyclical patterns
appear in many of these interpreta-
tions, the patterns are so obscure that
little credence can be put on their
meaning.
Tree Rings and Environmental
Cyclic Behavior
Certain species of trees respond to
physiological behavior by doing all of
their yearly growth in a particular
period of time. Thus, growth itself
is harmonic. The amount of growth
produced each year, however, varies
in response to environmental changes.
Trees in a uniform environment, or
one that remains fairly constant year
in and year out, produce tree rings
of a uniform width over a given
period of years. In contrast, trees
growing in areas where environmen-
tal changes are quite pronounced will
reflect those changes in variable ring-
widths for a given period of years.
(See Figure III-5) In areas where one
growth-controlling factor assumes
dominance over the others, this factor
can be isolated; variations of ring-
widths then permit study of this par-
ticular type of variable environmental
condition. In certain areas the con-
Figure III -5 — PRECIPITATION PATTERNS FROM TREE RINGS
1700
17S0
1800
1900
The photograph shows tree rings beginning about 1690 and ending about 1932.
The rings were used to estimate whether the year was wet or dry; moisture was
then computed to provide the graph in the lower part of the diagram. Since varia-
tions in atmospheric circulation cause periods of wetness and dryness, the ring-
width records can be calibrated with surface pressure and used to map anomalies
of the atmospheric circulation for periods of time in which few if any historical
data exist.
60
OCLICAi ;
trolling factor might be soil moisture,
in others it might be summer temper-
atures, and in still others it might be
solar radiation. If too many variables
enter the picture, to a point where
they cannot be isolated, the growth
patterns become "confused"; in the
present state of knowledge, they are
of little value for this type of study.
Numerous studies are being con-
ducted on tree growth. Those con-
cerned with the bristlecone pine
(Pinus aristata Engelen) in the White
Mountains of eastern California are
among the more important. Living
bristlecone trees as old as 5,000 years
or more have been studied and a good
yearly growth chronology for that
period of time has been developed.
Bristlecone snags and other pieces of
deadwood have enabled the chronol-
ogy to be extended back for over
7,000 years. Similar but shorter
chronologies have been developed in
other areas throughout many parts
of the northern hemisphere. Some
work has been done in the southern
hemisphere but none has yet attained
the length of the bristlecone studies.
Although numerous studies on
these tree-ring series have been made
by meteorologists, climatologists, and
statisticians, as well as dendrochron-
ologists and others, no cyclic pattern
has been detected in spite of the
annual variation that exists. The non-
uniform periods of good and poor
growing conditions for the bristlecone
show a cycle-like behavior. But be-
cause of the wide variation in inten-
sity and duration, one can "screen"
the data to find almost any cycle
length desired, or even none at all.
These data appear to be promising
from the standpoint of cyclic be-
havior, but at present they are of lim-
ited value.
Pollen Profiles and Environmental
Cyclic Behavior
The number of pollen and spores
recovered from any depositional se-
quence is the result of a wide variety
of variable factors which are not yet
well understood. Climatic factors are
involved in the production and dis-
persal of pollen of the various wind-
pollinated species; in addition, a dif-
ferential is caused by preservation and
recovery from the sediments. Experi-
mental work is being done on almost
every aspect of these wide variations,
and there is hope that the future will
see at least a reasonable solution to
many of these problems.
Profiles represent a random count
of various wind-pollinated species re-
covered from sediments. Seldom does
the palynologist working with recent
materials give an absolute pollen
count of every grain present on the
slide. These counts are treated in a
statistical manner in an attempt to
overcome bias caused by differential
production (plants too close to the
depositional area) or differential pres-
ervation (oxidation). Such profiles
give only a gross representation of the
true situation. Furthermore, no an-
nual variation in past pollen produc-
tion or preservation can be detected
from such profiles unless the variation
is frozen into annual deposits such as
a varved clay sequence.
Pollen profiles are being interpreted
as essentially representing the vegeta-
tive cover existing at the time the pol-
len was produced. The vegetative
cover was, in turn, a response to envi-
ronmental conditions during
periods, and those environmental con-
ditions are interpreted as being of
climatic significance.
Present Status
There is no question that, under cer-
tain environmental conditions, plants
produce different amounts of growth
in the annual layers of wood, and dif-
ferent amounts of pollen are produced
and dispersed during the pollen-
production seasons. Tree-growth and
pollen studies are still, however, in
what one could call a primitive state.
We are only now learning what the
problems actually are. As soon as the
problems can be better defined, con-
centrated effort can be made toward
their solution. At the present time,
only trends can be detected in the
various environmental conditions; no
scientific prediction can yet be made
from these trends.
In general, more physiological
studies are needed regarding the con-
nection between environment and
tree-ring growth, especially in quanti-
tative amounts. Such studies need to
be made on a variety of species grow-
ing under a wide variety of condi-
tions. Once these measurements are
made and understood, considerable
statistical work (computer analysis)
will be necessary to reduce the data to
usable forms. We are still in need of
better knowledge on pollen produc-
tion and dispersal, on pollen preserva-
tion and recovery, and on statistical
(or computer) analyses of recovered
grains. These studies will be of
limited value, however, if we do not
also have a much better understand-
ing of all aspects of the physical
matrix comprising the natural envi-
ronment.
61
PART III — CLIMATIC CHANGE
2. CAUSES OF CLIMATIC CHANGE
Basic Factors in Climatic Change
It is useful to introduce the prob-
lem of climatic change by considering
the definition of climate. Practical
definitions of the term "climate" vary
in their specifics from one authority to
another. All are alike, however, in
distinguishing between climate and
weather (and between climatology
and meteorology) on the basis that
climate refers to "average" atmos-
pheric behavior whereas weather
refers to individual atmospheric events
and developments. On the face of it,
then, it might seem that we are left
simply with the decision of what time
interval to choose over which to aver-
age the observed weather into "the
climate." By "average" is meant aver-
age statistical properties in all re-
spects, including means, extremes,
joint frequency distributions, time-
series structure, and so on.
Climatic Change as a Fundamental
Attribute of Climate
Were atmospheric behavior to pro-
ceed randomly in time, the problem
of defining climate would reduce to a
straightforward exercise in statistical
sampling. We could make our esti-
mate of climate as precise as we wish
merely by choosing an average inter-
val that is sufficiently long. One diffi-
culty arises immediately because our
knowledge of past atmospheric be-
havior becomes less and less detailed
(and less and less reliable) the further
back in time we go. But there is an-
other, more important difficulty: If
our knowledge of past climates is im-
precise, it is at least good enough to
establish that long-term atmospheric
behavior does not proceed randomly
in time. Changes of climate from one
geological epoch to another, and ap-
parently also those from one millen-
nium to another, are clearly too large
in amplitude to be explained as ran-
dom excursions from modern norms.
When one examines modern recon-
structions of the paleoclimatic rec-
ord, one might be led to suppose that
geological changes of climate — such
as those associated with the alternat-
ing glacials and interglacials of the
Pleistocene ice age — are smoothly
varying functions of time, readily dis-
tinguishable from the much more
rapid variability of year-to-year
changes of atmospheric state. In
other words, one might suppose that
each part of a glacial cycle has its own
well-defined climate, just as each sea-
son of the year is revealed by modern
meteorological data to have its own
well-defined climate. In such a case,
the averaging interval needed to ob-
tain a stable estimate of present-day
climate should be long enough to sup-
press year-to-year sampling variabil-
ity, but short in comparison to the
duration of a glacial cycle.
If we succumbed to the foregoing
rationale for defining climate, we
would probably be living in a fool's
paradise. The reason is simple
enough: the apparent regularity of
atmospheric changes in the geological
past is only an illusion, attributable to
the inadequate resolving power of
paleoclimatic indicators. Most such
indicators act to one degree or another
as low-pass filters of the actual cli-
matic chronology. If our more recent
experience — based on relatively
higher-pass filters such as tree-rings,
varves, ice-cap stratigraphy, and pol-
len analysis applicable to post-glacial
time — is any guide, the state of the
atmosphere has varied on most, if not
all, shorter scales of time as well.
In other words, the variance spec-
trum of changes of atmospheric state
is strongly "reddened," with low-
frequency changes accounting for rel-
atively large proportions of the total
variance (in the broadband sense).
At the same time, important gaps in
the spectrum of climatic change have
yet to be identified and may not even
exist. Taken together, these circum-
stances imply that there may be no
such tiling as an "optimum" averag-
ing interval, and therefore no assur-
ance that we can define (let alone
measure) a unique, "best" estimate of
what constitutes average behavior of
the atmosphere.
To summarize, atmospheric state is
known to vary on many scales of
time, and it cannot be ruled out from
present knowledge that it varies on all
scales of time (from billions of years
all the way down to periods so short
that they are better defined as mete-
orological variability). Thus it can be
argued that the very concept of cli-
mate is sterile as a physical descriptor
of the real world as long as it adheres
to the classical concept of something
static. In any event, present-day cli-
mate is best described in terms of a
transient adjustment of atmospheric
mean state to the present terrestrial
environment.
The Problem of Causes
If climate is inherently variable, as
here suggested, different interpreta-
tions can be lent to the variability.
The "Slave" Concept — One inter-
pretation is the conventional one,
which can be called the "slave" con-
cept of climatic change. This em-
62
CAUSES Ol
bodies the idea that the average
atmospheric state is virtually indis-
tinguishable from an equilibrium
state, which in turn is uniquely con-
sistent with the earth-environmental
conditions at the time; in this view,
the atmosphere requires a relatively
short time to adjust to its new equilib-
rium state when the earth-environ-
mental conditions change.
The "Conspirator" Concept — An-
other interpretation can be called the
"conspirator" concept of climatic
change. This concept considers that
the average atmospheric state is in-
fluenced as much by its own past
history as by contemporary earth-
environmental conditions, that there
may be more than one equilibrium
state that is consistent with those en-
vironmental conditions, and that the
choice of equilibrium state approxi-
mated by the actual atmospheric state
at any given time depends upon the
antecedent history of the actual state.
Sliarp Distinctions — The distinc-
tions between these two concepts is
sharp for long-period climatic change,
such as the change from Tertiary to
Quaternary times. On such a time-
scale, the dynamic and thermody-
namic time-constants of atmospheric
processes are infinitesimal, even if one
chose to include the oceans and the
polar ice-caps as coupled "atmos-
pheric" processes. As now seems
plausible, earth -environmental
changes included gradual sea-floor
spreading and continental drift, to-
gether with a gradual increase of
average continental elevation. It is
usually assumed that the climate acted
in keeping with the "slave" concept
throughout and that, after a certain
point in the course of continental drift
was reached (perhaps when the Arc-
tic Ocean was isolated), the equilib-
rium climate was transformed in a
deterministic manner from a glacial-
inhibiting pattern to a glacial-stimu-
lating pattern.
On the other hand, it is possible to
argue, following Lorenz, that the
actual climate of the Quaternary was
not necessarily preordained by its
contemporary environmental state;
that the evolution of climate to its
Quaternary mode was not a deter-
ministic evolution but a probabilistic
one that might have turned out very
differently under identical conditions
of continental drift and other environ-
mental change. The different Quater-
nary outcomes (two or more) would
have followed from differences in the
precise course of the climate itself,
due either to transient environmental
disturbances or perhaps to "random"
excursions of atmospheric state along
the way.
Subtle Distinctions — With regard
to relatively rapid climatic change,
however, the distinction between the
"slave" and the "conspirator" con-
cepts of change is much more subtle
in character, and perhaps unrecog-
nizable within present bounds of
either theory or observation. The rea-
son for this is to be found in the inti-
mate dynamic and thermodynamic
coupling that exists between the at-
mosphere and the oceans, and to a
lesser extent in the coupling between
the atmosphere, the oceans, and the
polar ice-caps. These couplings intro-
duce long time-constants into the
changes of atmospheric state, and re-
sult in various forms of autovariatiou
in the total system, on the time-scale
of decades and centuries. In the
course of such autovariation, the at-
mosphere itself may be said to obey
the "slave" principle. But in a rela-
tively limited period of years, the
coupled atmosphere-ocean system
would exhibit changes of state that
are not independent of its initial state.
In this case, the system is more prop-
erly described as obeying the "con-
spirator" principle. To complicate
matters further, it is conceivable that
the autovariation of the atmosphere-
ocean system is riding on top of a
transient of the Lorenz type already
mentioned.
In the presence of Lorenz-type
transients, the effect of systematic en-
vironmental changes on p
climate (changes, for exam]
ing secular increases of carbc
oxide (CO:;) or other consequences ot
human activities) might be so badly
confounded as to be totally unrecog-
nizable. Even without such transients,
however, atmosphere-ocean autovari-
ation could effectively obscure the
effect of systematic environmental
changes that we are seeking to dis-
cover.
Rationale for the Isolation of
Human from Natural Factors in
Climatic Change
What rationale, then, are we to fol-
low in establishing the climatic effects
of systematic environmental change
on the scale of decades and centuries?
More specifically, how do we go about
the task of isolating the contribu-
tion of man's activities to twentieth-
century climatic change?
First of all, there seems no real pos-
sibility of detecting Lorenz-type tran-
sients in present-day climate, so we
will have to proceed on the assump-
tion that they are not now occurring
nor are they likely to be induced in
the foreseeable future by further
environmental change from human
activities.
Second, while we should not hesi-
tate to use presently available esti-
mates of the climatic effects of atmos-
pheric pollution and other forms of
environmental change as an interim
guide in assessing the potential cli-
matic hazards of various human ac-
tivities, we should also remember that
such estimates are highly tentative.
We should take pains not to put
undue confidence in them.
Shortcomings of the Present Data
Base — In this connection, there are
two important points to consider:
1. Most present estimates of the
climatic impact of human activ-
ities are based on relatively
63
PART III — CLIMATIC CHANGE
simple hydrostatic heat-balance
models (as refined, for example,
by Manabe and used by him to
estimate the thermal effect of
variable CO-, stratospheric wa-
ter vapor, surface albedo, and
the like). Manabe himself has
often stressed the limitations of
such models, the most impor-
tant of which are: that they do
not take account of atmospheric
dynamics other than purely
local convective mixing; and
that they do not take into ac-
count changes of atmospheric
variables other than the varia-
ble that is explicitly controlled
as a parameter of the calcula-
tion (plus water vapor in those
experiments stipulating a con-
stant relative humidity).
2. Climatic changes caused by nat-
ural agencies, and those possi-
bly caused by human agencies,
are not necessarily additive. For
example, by analysis of past
data on CO- accumulation in
the atmosphere, roughly 50 per-
cent of all fossil COj added to
the atmosphere appears to have
been retained there. Using pub-
lished United Nations projec-
tions of future fossil CO-
production, together with a
constant 50 percent retention
ratio, it can be predicted that by
a.d. 2000 the total atmospheric
CO- load will have exceeded its
nineteenth-century baseline by
more than 25 percent. As
pointed out by Machta, how-
ever, recent atmospheric CO-
measurements at Mauna Loa
and other locations indicate that
the atmospheric CO- retention
ratio has been dropping steadily
since 1958, to a present value
of only about 35 percent.
It may be significant that the 50
percent retention figure applied to a
time when world average tempera-
tures were rising, and that the ob-
served decline since 1958 applies to a
time when world average tempera-
tures have been falling. It is conceiv-
able, though certainly not proven,
that the reversing trend of world cli-
mate in recent years has somehow
altered the rate at which the oceans
can absorb fossil CO2. If this is the
case, we are witnessing an interactive
effect whereby climatic changes pro-
duced by one agency (presumably a
natural one) are at least temporarily
reducing the climatic impact of an-
other agency (in this case, an inad-
vertent human one). Such interactive
effects are very poorly understood,
and yet they may be a very important
element in the evolution of present-
day climate.
The Use of Advanced Mathematical
Models — To return to our question
of what rationale we should follow in
our study of contemporary climatic
change and of human influences on
climate, we are left with little choice.
We have to rely on the development
of advanced mathematical models of
the global atmosphere that will be
suitable for long-term integration to
generate stable climatological statistics
and will be capable of simulating
many dynamic and thermodynamic
processes in the atmosphere and at
the earth's surface. Relatively sophis-
ticated models of these kinds have
already been developed, at least one of
which has been expanded to deal with
coupled atmosphere-ocean systems.
Experiments with such models have
begun to lay a solid foundation for a
quantitative theory of global climate
and have elucidated the climate-
controlling influence of the general
atmospheric and oceanic circulations.
There appears to be no limit to the
refinement possible in such models,
other than the limits imposed by com-
puter capacity and speed.
The manner in which such numeri-
cal experiments bear on the study of
climatic change is essentially twofold:
1. The experiments verify that a
wide range of environmental
factors have a bearing on the
global pattern of atmospheric
circulation and climate. They
confirm that the most impor-
tant factors in this respect are:
(a) solar emittance; (b) the
geometry of the earth-sun sys-
tem including the orbital and
axial motions of the earth;
(c) the distribution of oceans
and land masses; (d) the state
of the ocean surface which,
along with the juxtaposed at-
mospheric state, governs the
fluxes of energy, moisture, and
momentum across the surface;
(e) the state of the land surfaces
with respect to albedo, thermal
capacity, water and ice cover,
relief, and aerodynamic rough-
ness; and (f) the gaseous and
aerosol composition of the at-
mosphere itself. To the extent
that all of these factors may
vary with time, either slowly
or rapidly, in response to forces
other than the contemporary at-
mospheric state itself, all such
factors are automatically to be
regarded as potential causes of
climatic change.
2. In the numerical experiments, it
is possible to simulate the be-
havior of circulation and cli-
mate as a function of arbitrarily
chosen boundary conditions
and atmospheric constituency,
which enter the experiments as
controllable parameters. This
makes it possible to vary any
of the environmental factors
listed above and determine how
the circulation and climate re-
spond. In this way, various
theories of climatic change can
be tested in terms of their mete-
orological consistency. With the
further refinement of joint at-
mosphere-ocean models, the
more realistic modeling of con-
tinents and ocean basins, and
the introduction of ice-cap in-
teractions into the models, the
range of factors in climatic
causation that are amenable to
this kind of study will eventu-
ally became almost exhaustive
of all reasonable possibilities.
64
CAUSES OF CLIMATIC CHANGE
Factors related to human activi-
ties would, of course, be in-
cluded.
Other Requirements — As neces-
sary as such model experiments may
be to the study of climatic change, it
is important to realize that they are
not sufficent to solve the problem of
climatic change. It is not enough that
we develop the ability to measure the
response of climate to varying envi-
ronmental conditions. If we are to
decipher past climatic changes or to
predict future changes, it is necessary
to determine which environmental
controls of climate have been (or will
be) doing the varying, at what rate,
and in what direction.
At present, there is a deplorable
lack of understanding about the vari-
ability of our environment. There can
be no guarantee that the necessary
understanding will ever be acquired in
full, for that in turn may depend on
unknowable past events and unpre-
dictable future events. But we should
learn what we can, for in no other
way can we be certain whether the
climatic changes of the twentieth cen-
tury are or are not causally related to
man's activities.
The Radiation Balance
It has become evident that man can
change the entire atmosphere of his
planet in certain subtle ways. And he
can modify large regions in rather
obvious ways — for example, with
smoke and smog. There are now new
dimensions to his leverage on the at-
mosphere as he flies large jet aircraft
even higher in the stratosphere, and
as booster rockets of the Saturn class
introduce hundreds of tons of exhaust
into the thin reaches of the upper
atmosphere.
The effects of these changes on the
environment are diverse. We have re-
cently become aware of the evident
and sometimes acute effects of pollu-
tion in the world's cities. Now we
realize that man may even be able to
change the climate of the earth. This
is one of the most important questions
of our time, and it must certainly rank
near the top of the priority list in
atmospheric science.
General-Circulation Models
of the Atmosphere
In recent years, it has been possible
to create fairly realistic numerical
models of the global atmosphere that
behave very much the way the real
atmosphere does. (See Figure III-6)
The atmosphere is a great heat engine
that runs on solar energy, taking ad-
vantage of the greater amount of heat
that reaches the equatorial zone. The
function of the heat engine is to trans-
port this heat from the equator to the
poles. In the process, the atmosphere
moves with the patterns of the winds
seen on any weather map.
Figure 111-6 — COMPUTER SIMULATION OF SEA-LEVEL PRESSURE FIELD
Sea level pressure distribution for the western hemisphere has been simulated by
a numerical model developed by the National Center for Atmospheric Research.
The time is 42.83 days into the simulation and represents a moment in a typical
January. The contour interval is 5 millibars. White areas represent clouds. The
influence of these clouds is taken into account in the radiation calculations. Areas
of high pressure are indicated by H, areas of low pressure by L.
65
PART III — CLIMATIC CHANGE
Modeling of the atmospheric heat
engine is complicated by the existence
of another, more sluggish but massive
heat engine — namely, the oceans.
While the ocean does not move as fast
as the atmosphere, its tremendous
heat capacity more than offsets its
slow movement. The ocean circula-
tion is coupled to that of the atmos-
phere, and nearly as much heat is
transported from equator to pole in
the oceans as in the atmosphere.
The key to this atmosphere-ocean
system, the ultimate driving force, is
the solar radiation that is absorbed,
mostly in the equatorial regions, and
the infrared radiation that is emitted
back to space at all latitudes. One
cannot consider the heat involved in
radiation, however, without also con-
sidering the internal heat released into
the atmosphere bv the condensation
of water vapor. In fact, most of the
heat that is transported from the
equator to the middle latitudes is in
the form of the latent heat of water
vapor, heat that is released whenever
it rains or snows.
Experimental general -circulation
models of the atmosphere that have
been run on large computers at the
National Center for Atmospheric Re-
search (NCAR), the Geophysical Fluid
Dynamics Laboratory of the National
Oceanic and Atmospheric Adminis-
tration (NOAA), and the University
of California at Los Angeles also take
into account the effect of the moun-
tain ranges of the world, the rotation
of the earth, and the complex proc-
esses that exchange heat, moisture,
and momentum vertically by means
of convection, particularly in the
tropics. All these processes can be
related to each other by a set of dif-
ferential equations that involve time.
A model is made to "run" by integrat-
ing these equations in small time-
steps, and the result is a model of a
moving fluid system that behaves
very much like the real atmosphere.
Future Refinements — With these
general-circulation models we can, in
principle, do "experiments" to learn
how the atmosphere would change
with time if there were a change, for
example, in the ability of the atmos-
phere to transmit solar radiation due
to smoke, haze, or smog, or how it
would change if there were a growth
or shrinking of the size of the great
polar ice-caps.
Actually, however, we are still a
long way from realizing a model that
is adequate for such experiments in
"climatic change." The current gen-
eral-circulation models are designed
to show the hour-to-hour, day-to-day,
and week-to-week changes; we would
run out of computer time if we used
them to study really long-term
changes. Long-term changes in this
system would certainly involve
changes in the ocean. Hence, it would
not be enough to consider only the
circulations of the atmosphere. Never-
theless, there is hope that, in time, we
will be able to develop theoretical
numerical models with which to con-
duct experiments on the atmosphere-
ocean climate and how it will change
with changes in the heat available to
the system. These models will require
a considerable effort in developing
quasi-statistical shortcuts and the
availability of larger computers than
we have now.
The Radiation Budget
As mentioned, radiation is the ulti-
mate source of energy to drive the
complex atmosphere-ocean system. In
order to gain an idea of the role that
radiation plays in keeping the system
in motion, we can perform a simple
calculation of the rate of energy input
from the sun as compared to the
amount of energy that the atmos-
phere contains at any time. The solar
radiation absorbed by the system is
about 600 calories per cirr per day,
and the average total thermal heat
energy of the atmosphere is about
60,000 calories per crrr. This means
that if the solar radiation were cut off
abruptly, about 10 percent of the
energy of the atmosphere would dis-
appear within ten days. This is enough
to cause an appreciable change in the
circulation. Such a rough calculation
indicates that the atmosphere will re-
spond to a change of heat input in a
week or less.
Determinants of the Earth's Albedo
— The solar radiation that reaches
the earth is partly reflected back into
space, partly absorbed by the atmos-
phere, but mostly absorbed by the
surface. (See Figure III-7) In the
1940's it was estimated that about
40 percent of the solar radiation was
reflected back to space, but more re-
cent estimates, based largely on satel-
lite observations, have been lowered
to about 30 percent. This average re-
flectivity is referred to as "the earth's
albedo." The fact that there has been
such a large uncertainty as to the
magnitude of the albedo is testimony
to our general uncertainty about the
amount of energy available to the
system.
Cloud Cover — Another important
variable is the cloud cover, since
clouds are generally much more highly
reflecting than the surface of the
earth. The same is true of snow and
ice. An increase in cloud cover in-
creases the albedo. For example, a
change of 5 percent in the average
cloudiness of the equatorial zone, an
amount that would go unnoticed,
would change the albedo of the earth
by about 1.5 percent. This would
represent an appreciable decrease in
the energy available to drive the
atmosphere-ocean system.
The same effect as a decrease in
amount of cloud cover would be
achieved by a decrease in the reflec-
tivity of the clouds, since both would
decrease the net albedo of the earth.
Clouds moving over regions with in-
dustrial pollution, such as Europe,
show a decrease in reflectivity from
about .95 (for pure water clouds more
than half a kilometer thick) to .80 or
.85. This much reduction in cloud
66
CAUSES OF CLIMATIC CHANGE
Figure MI-
FACTORS IN THE RADIATION BALANCE OF THE EARTH
SELECTIVE ♦_, .
ABSORPTION t Y ^'
nJ^t AND EMISSION ~-~yL~~ /] '
f\ ^7\thermal
1 - FMISSION
^
RAYLEIGH SCATTERING
i
EMISSION
FROM CLOUD
THERMAL
EMISSION OF
ATMOSPHERE
( ~
J'h CtOUD REFLECTION
rV~j AND ABSORPTION
SELECTIVE ABSORPTION
•;\ AND
EMISSION
CLOUD
ABSORPTION 4~
AND 5
SCAHERING - ■
ABSORPTION AND EMISSION
THERMAL EMISSION
FROM EARTH SURFACE
ABSORPTION AND REFLECTION
BY EARTH SURFACE
The diagram indicates the major components in the global radiation balance. The
albedo, or reflectivity, is composed of the radiation reflected from the ground,
clouds, aerosols, and other materials that might scatter incoming solar radiation.
reflectivity, in the unlikely event that
all clouds were so affected, would
have about the same effect as a 5 per-
cent reduction in cloud amount.
Budyko, at Leningrad, and Sellers,
at the University of Arizona, have
taken this energy calculation one step
further, arguing that a decrease of
only 1.6 to 2.0 percent in the solar
radiation available to the earth would
lead to an unstable condition in which
continental snow cover would ad-
vance all the way to the equator, with
the albedo raised by the greater snow
cover to the point where the oceans
would eventually freeze. Lest this
rather frightening calculation be taken
too seriouslv, it should be mentioned
that there is no evidence that a mech-
anism for a change of as much as 1.5
percent actually exists, or ever has in
the history of the earth. The model
nevertheless illustrates the delicacy of
our planet's thermal balance.
Aerosols — The aerosols that fill
the atmosphere — natural haze, dust,
smoke, smog, and so on — probably
play an important role in the radiation
balance of the earth, but this is one of
the great uncertainties in the theory
of how the atmosphere behaves.
Aerosols in cloudless air probably in-
crease the albedo to some extent,
and they absorb sunlight themselves.
Also, as we have noted, they can
change the reflectivity of clouds. We
are quite certain that variations in the
solar radiation absorbed by the earth's
atmosphere and surface, due to
changes in turbidity or total aerosol
content of the atmosphere, are signifi-
cant. Furthermore, as will be noted
below, aerosols in the atmosphere can
be greatly affected by man and vol-
canic activity.
Factors Affecting Loss of Terrestrial
Heat — On the other side of the
ledger by which we keep track of the
amount of heat into and out of the
atmosphere-ocean heat engine is the
loss to space of terrestrial heat by in-
frared radiation. Over a period of a
year or so, the amount of radiation
lost by infrared radiation must almost
exactly balance the amount of solar
radiation absorbed by the earth and
its atmosphere. If this did not hap-
pen, the earth would rapidly heat or
cool.
As a general principle, any sub-
stance in the atmosphere that absorbs
infrared radiation will slow the cool-
ing of the surface. The reason for this
is that the energy radiated from the
surface is absorbed by the absorbing
substance in the atmosphere, thus
heating the atmosphere which in turn
radiates back toward the ground. In
effect, an absorbing layer acts as a
radiation blanket, and its presence
will result in a higher surface tem-
perature.
An auxiliary effect of this absorb-
ing blanket will be an increase in the
stability of the lower part of the at-
mosphere, between the surface and
the absorbing layer. This increase in
stability will reduce convection in the
lower layers. The ability of the at-
mosphere to stir itself by convection
is a principal source of cumulus
clouds, so that a decrease in convec-
tion would also decrease precipitation.
Infrared Absorbers — There are
two main classes of infrared absorbers
in the atmosphere: trace gases (water
vapor and carbon dioxide (CO;;) being
the most important in the lower at-
mosphere) and aerosols of all kinds,
including clouds. Various estimates
have been made of the effect of in-
creasing COj in the atmosphere, since
man has in fact been able to raise
the total amount through burning fos-
sil fuels. Since 1900, the amount of
CO2 has increased an average of 10
to 15 percent, and this trend has
usually been cited to account for the
observed rise in the average surface
temperature of 0.2 centigrade up to
1940. The theoretical calculations of
Manabe and Weatherald indicate that
a doubling of the COj content in the
atmosphere would have the effect of
raising the temperature of the atmos-
phere (whose relative humidity is as-
67
PART III — CLIMATIC CHANGE
sumed to be fixed) by about 2 centi-
grade, an appreciable change.
The role of aerosols in the radiative
balance cannot be calculated with
anything like the certainty of that for
carbon dioxide. Various estimates
have been made of the effect of
aerosols, with conflicting results. The
principal effects of aerosols are to in-
crease the scattering of sunlight in the
atmosphere and also to absorb sun-
light, the two effects being about
equal. Thus, Robinson, in England,
reports an average decrease of 25 per-
cent in the amount of sunlight reach-
ing the surface due to aerosols, and
presumably at least half of this
amount went into heating the atmos-
phere. In clear air, such as that found
in the polar regions, the effect of
aerosols is much less, but in the
tropical zone the turbidity of the at-
mosphere, probably due primarily to
natural haze from vegetation, is high
all the time.
Man-Made Aerosols — Aerosols
should be taken into account in any
calculation of the radiative balance of
the earth-atmosphere system, but the
fact is that we do not yet know how
to do this with certainty. Further-
more, there is the practical question
of how man-made aerosols compete
with natural aerosols.
The haze observed in many parts of
the world far from industrial sources
originates chiefly in the organic mate-
rial produced by vegetation, with
large contributions from sea salt from
the ocean and dust blown from dry
ground. At times, volcanic activity in
the tropics produces a worldwide in-
crease of the aerosol content of the
high atmosphere. It is estimated by
Budyko, for example, that the solar
radiation reaching the ground after
the 1963 eruption of Mt. Agung, in
Bali, was reduced in the Soviet Union
by about 5 percent, a significant at-
tenuation whose total effect on the
global radiation balance is not clear.
In contrast to these natural aero-
sols, man has overwhelmed nature in
certain parts of the world where in-
dustrial smog and smoke have an evi-
dent effect on the clarity of the atmos-
phere. Observations in a few cities,
such as Washington, D. C, and Uccle,
Belgium, have documented the in-
crease in turbidity and the decrease in
solar radiation reaching the surface
over the past few decades, even
though progress has been made in the
United States and Europe in reducing
the production of smoke from coal-
burning heat sources.
An additional complication, a pos-
sible effect of man-made contaminants
in the atmosphere, is the observed
reduction of the albedo of clouds due
to contaminants absorbed in cloud
droplets. This effect must also be
taken into account in a complete cal-
culation of the radiation budget and
man's effects on it.
Needed Scientific Activity
In view of the uncertainties in the
many factors involved in the radiation
balance of the earth, and the possibil-
ity that man is significantly affecting
the radiation balance by his introduc-
tion of aerosols and his increase in the
COi; content, it is necessary to inten-
sify our studies of the effects of these
factors on the climate.
Models — The key to such studies
is the development of adequate clima-
tological models on which experi-
ments can be run. One would, for
example, study the change in the
average temperature in various re-
gions of the globe for certain changes
in the optical characteristics of the
atmosphere resulting from aerosols
and carbon dioxide. There are many
feedbacks in this system, and the
model should take as many as pos-
sible into account. A major feedback,
already referred to, is that due to
changing ice and snow cover in the
polar regions; another is due to
change of cloud cover; the two prob-
ably react in the opposite direction to
a change in average temperature.
Since the oceans are important in
the long-term heat balance of the sys-
tem, a climatic model must certainly
include oceanic circulations, even
though they are largely secondary to
atmospheric circulations in the sense
that the atmosphere drives the sur-
face currents. Progress in modeling
oceanic circulation has been made in
a number of places, notably the Geo-
physical Fluid Dynamics Laboratory
of NOAA, NCAR, Florida State Uni-
versity, and The RAND Corporation.
The challenge, eventually, will be to
combine the atmospheric and oceanic
circulations in one model.
Monitoring — It is not sufficient to
develop a theory without being aware
of changes actually taking place in the
real atmosphere. For this reason it
will be necessary to continue to moni-
tor the climate, as is being done in a
number of stations throughout the
world. In addition to the usual pa-
rameters of temperature, wind, and
precipitation, the composition of the
atmosphere and its turbidity need to
be monitored better than they are
now. This is not a simple task, since
quantitative measurements of trace
gases require fairly elaborate tech-
niques, while measurements that de-
scribe the aerosol content of the at-
mosphere should provide information
on the optical properties of these
aerosols as well as their concentration.
It is necessary to know how these
aerosols affect incoming solar radia-
tion and outgoing infrared radiation.
This has not been done adequately,
except on a few occasions using spe-
cial equipment.
Satellites have been useful in many
ways in obtaining new information
about the global atmosphere, and they
can contribute significantly to the
monitoring task. Except for cloud
cover, however, observations to date
have not been sufficiently quantita-
tive. Cloud cover can and should be
monitored by satellites. Satellites can
also monitor snow and ice cover, al-
though there is a problem during the
polar night when pictures cannot be
taken in the usual manner. This situa-
68
CAUSES OF e; IANGE
tion is improving rapidly, since the
High Resolution Infrared Radiom-
eters, of the type used on the Nimbus-
4 and ITOS-1 satellites, can obtain
pictures by day or night and even
provide an indication of the heights of
cloud tops. Nimbus-F, scheduled for
launching by the National Aeronau-
tics and Space Administration
(NASA) in 1974, may carry an ab-
solutely calibrated radiation experi-
ment that could mark the beginning
of direct quantitative measures of the
total heat budget of the earth. Mea-
surements of lower atmospheric com-
position, or pollution, from satellites
have been proposed, but at this time
they seem to be further in the future.
Ozone, a trace gas found mostly in
the stratosphere and upper tropo-
sphere, has been measured, but this
component may be of minor concern
in the present context.
A Perspeciive on Man-Made Pollu-
tion — The possible change in the
radiative characteristics of the upper
atmosphere due to rockets can prob-
ably be dismissed, because even ex-
treme assumptions about numbers of
Saturn-class rockets being launched
lead to negligible changes. The con-
tribution of jets to water vapor and
aerosols in the stratosphere may also
be trivial. Recent studies by the Na-
tional Academy of Sciences, by Ma-
nabe and Weatherald, and by others
strongly suggest that it is. Contrails
are likely to have a climatic influence
only when they trigger the formation
of extensive bands of cirrus cloud
which mature, with the passage of
time, to a sufficient optical depth in
the infrared to produce either signifi-
cant blanketing or reduction of in-
coming visible solar radiation.
One cannot say for certain that, on
the occasions when jet-airplane con-
trails produce cirrus clouds, the cirrus
clouds would not have formed natu-
rally. But there are many occasions,
some lasting for several days, when
major portions of the United States
are crisscrossed by jet-airplane con-
trails that do not dissipate, but instead
spread out until major fractions of the
sky are covered by thin cirrus of suf-
ficient intensity to be of radiative sig-
nificance. What needs to be done
is to conduct quantitative studies, in
selected areas of the earth, of the
radiative losses to space that occur
with and without cirrus clouds. Then
there needs to be a rather careful ex-
amination of the degree to which
these cirrus can be artificially trig-
gered. The stability of the large-scale
circulation is an extremely important
matter. We know that large trough
developments occur in the 300-milli-
bar circulation, particularly in the late
winter and spring seasons, in a way
that is difficult if not impossible to
predict. It is quite conceivable that
cirrus cloud formations at high lati-
tudes over warm sources, as over the
Gulf of Alaska, may be important in
this regard.
The atmosphere-ocean system de-
pends on the heat available to run it,
and this is the result of a delicate bal-
ance between heat received from the
sun and re-radiated to space. There
are ways to disturb this balance, and
the ice ages of the past are proof that
nature sometimes does, in fact, alter
it. Man might do the same, and this
possibility deserves the most careful
study. There has been much hand-
waving of late by "prophets of doom."
While virtually none of these people
is a scientist, atmospheric scientists
have not been able to make convinc-
ing rebuttals so far.
The earth actually has a remarkably
stable life-support system, and man
is unlikely to be able to move it far
from its equilibrium. To mention a
few examples: Aerosols, of the sort
that man or nature creates, only re-
main in the atmosphere for about a
week on the average. Thus, indus-
trial pollution in the United States
hardly has time to reach Europe be-
fore it is washed from the air. Further-
more, natural sources of contamina-
tion from vegetation, volcanoes, the
oceans, and the deserts still far out-
weigh all of man's contributions,
taken on a global scale. With respect
to the balance built into our highly
variable clouds, an increase in mean
temperature would probably cause an
increase in moisture and cloudiness,
which in turn would reflect more solar
radiation back to space. Such a nega-
tive feedback, forcing the situation
back to equilibrium, is only one of
several mechanisms that we are be-
ginning to identify in the complex
atmosphere-ocean system.
Climatic Change and the Effects of Civilization
A worldwide climatic change has
been taking place for the past decade
or two. Its reality has been estab-
lished by scientists of the United
States, the Soviet Union, and
England.
The climatic amelioration that took
place between the late 1800's and
1940 has ended, and the mean tem-
perature of the earth appears to have
fallen since the middle of the present
century. (See Figure III-8) Some
dramatic environmental changes have
followed — e.g., the return of mid-
summer frosts in the upper Midwest,
record cold autumns in Ohio, rising
lake levels in East Africa, and mas-
sive encroachment of sea-ice on the
north shore of Iceland. With this
change, the circulation patterns of
the atmosphere also appear to have
changed. Any such changes on an
earth that is straining its capacity to
69
TART III — CLIMATIC CHANGE
Figure 111-8 — OBSERVED LAGGED TEMPERATURE
VARIATION OF THE NORTHERN HEMISPHERE
The observed temperature variation of the northern hemisphere has here been
corrected (see solid line) for the time lag of the ocean-atmosphere-soil system and
the system's response to factors that cause the variation of temperature. A half-
response-time of ten years was used. The broken line is the smoothed curve of
Figure 111-4 repeated for comparison.
feed the human population are sig-
nificant.
The theory of climate is so poorly
developed that we cannot predict ac-
curately whether the climatic trend
will continue, or how the distribution
of rainfall and frost will change if it
does. Clearly this knowledge is a
national and international need of
high priority. Clearly, too, we must
know whether any or all of the recent
fluctuation in climate is man-made,
and whether it can be man-controlled.
Lacking an adequate theoretical basis
for prediction, we can only look to
the past to see what kinds of changes
are possible, with what rapidity they
may occur, and what the causal fac-
tors might have been.
Basic Balances
Although numerical models of the
atmospheric circulation are still too
crude to simulate the climatic pattern
within an error small enough to be
less than the occasional ecologically
significant variations, certain basic
relations may be identified that can
yield information on some of the fac-
tors important to climatic change.
Ultimately the sun drives the at-
mosphere. The fact that we have
water in gaseous, liquid, and solid
states in the proportions we do is de-
pendent on our distance from the sun
and the fraction of the sunlight that
the earth absorbs. In the long run,
there must be the same amount of
heat re-radiated to space from the
atmosphere as is absorbed by the
earth.
The receipt of solar radiation occurs
on the cross-sectional area of the
earth, but re-radiation takes place
from four times as large an area —
i.e., the entire area of the globe. Thus,
SttR2 (1 - a) = 4ttR- I,
where 5 is the solar constant,
R is the radius of the earth,
a is the albedo, or "reflec-
tivity," of the earth,
and It is the mean outward in-
frared radiation flux from
the earth to space.
Satellite data show that It is fairly
uniform over the earth, on the annual
average, and that the albedo of the
earth is such that the above equation
is approximately balanced. The out-
ward radiation measured from space
is smaller on the average than that
emitted by the earth's surface, so that
S (1 - a) = 4 (to-To4 - AI)
where t is the emissivity of the
earth's surface,
a is the Stef an-Boltzman con-
stant,
To is the surface tempera-
ture of the earth,
AI is the difference between
the heat radiated upward
by the earth's surface and
that leaving the top of the
atmosphere for space —
the "greenhouse effect,"
and the overbar on c<jT,,4 indi-
cates an average over the
whole surface of the
globe.
The above equation is crude, but
it provides an insight into the factors
that might affect the general tempera-
ture state of the earth. Clearly, fluc-
tuations in solar intensity, the fraction
of incoming solar radiation that is
"reflected" or scattered away before
reaching the ground, and the "green-
house effect" are the major causes
of variation in the mean temperature
of the earth. A change of one or 2
percent in any one of these variables
is enough to produce a significant cli-
matic change, yet none of them is
known with this accuracy except per-
haps the solar intensity.
Albedo — The temperature of the
earth is most sensitively dependent on
the albedo of the earth-atmosphere
system — an increase of a few per-
cent would cool the earth to ice-age
temperatures. This variable — reflec-
tivity — can be measured by mete-
orological satellites, but not yet with
sufficient accuracy. The albedo is also
a variable that can be changed by
human activity, primarily by changes
in the transparency of the atmosphere
70
CAUSES OF C ! \NGE
resulting from particulate pollution.
According to Angstrom, a 7 percent
increase in the turbidity of the atmos-
phere will produce a one percent
change in albedo and a 1 -centigrade
change in world mean temperature.
The "Greenhouse Effect" — The
other variable that can be changed by
human activity is the "greenhouse
effect." This depends on such things
as the water-vapor content of the air,
dustiness, cloudiness, and, especially,
the carbon dioxide content. The car-
bon dioxide content of the atmosphere
has risen 11 percent or so in the past
century, and it is widely believed that
the rise is due to human activity in the
burning of fossil fuels and greater
exposure of soil humus and the like to
oxidation. (See Figure I1I-9)
In times past, changes in vegetation
and land distribution and elevation
affected the earth's albedo, as did
short-time changes in cloud and snow
cover. Volcanic activity, then as now,
produced a variable input of particu-
lates to the atmosphere, as did blow-
ing dust from desert areas — which
in turn affected the albedo. (See Figure
111-10) In earlier times, the distribu-
tion of land and sea, volcanic activitv,
the elevation of the land and nature
of the biota probably affected the
magnitude of the greenhouse effect.
The sun's intensity may also have
varied, though there is no evidence.
In addition, there are complex feed-
back mechanisms, such as additional
water vapor in the air at higher tem-
peratures, that increase the green-
house effect which in turn increases
the water-vapor content still more.
While increased volcanic activity
makes the atmosphere more turbid
and thus tends to depress the tem-
perature, it may also contribute to the
greenhouse effect and thus tend in
part to counteract the temperature
effect. The complete equation for re-
lating these effects is not known, but
it appears that the effect of turbidity
on the greenhouse effect is only about
10 percent of its effect on the albedo.
We do know, however, that there
is something new under the sun —
a population of humans sufficiently
numerous to modify the whole albedo
of the earth and the magnitude of the
greenhouse effect through their sheer
Figure 1119 — LAGGED TEMPERATURE CURVE FOR
THE NORTHERN HEMISPHERE CORRECTED FOR CO,
In this graph, the mean observed temperature variation for the northern hemisphere
has been adjusted for the time lag shown in Figure 111-8 and for the warming effect
of carbon dioxide (CO.). It can be seen that the increase of variation due to the
"greenhouse effect" of CO. is small compared with the variation of temperature
corrected for system lag. (Compare values of Figures 111-8 with 111-9) Only about
3 percent of the variance can be explained by the presence of CO..
Figure III -10 — LAGGED TEMPERATURE CURVE FOR THE
NORTHERN HEMISPHERE CORRECTED FOR CO, AND DUST
A
o
.2
QL
=>
V-
<
at
UJ
Q.
%
UJ
0
-.2
- 4
1
1
, 1 ,
1
, 1 ,
1
1
1
1
7
0
80
90
1900
10
20
30
40
50
60
7
3
YEAR
The mean observed temperature variation for the northern hemisphere has here
been adjusted for the time lag of the system, the warming effect of CO,, and the
effect of both stratospheric (volcanic) and tropospheric dust. The dust effect ex-
plains 80% of the variance of the adjusted temperature, with 63% due to strato-
spheric and 17% due to tropospheric dust. The resulting curve shows what tempera-
tures would be observed under conditions of direct solar radiation with cloudless
skies, although some residual errors remain. (Compare Figures III-4, 8, and 9)
71
PART III — CLIMATIC CHANGE
numbers and control of energy. Thus
man can, and probably has, modified
the climate of the earth.
The Climates of the
Past Century
From late in the nineteenth century
until the middle of the twentieth, the
mean temperature of the earth rose.
During this time the carbon dioxide
content of the atmosphere rose enough
to explain the global temperature rise
— apparently the first global climatic
modification due to man. At the same
time, local production of particulate
pollution was starting to increase
rapidly due to mechanization and
industrialization. By the middle of the
twentieth century, these trends —
amplified by a general population ex-
plosion and a renewal of volcanic
activity — increased the worldwide
particulate load of the atmosphere to
the point where the effect of these
particulates on the global albedo more
than compensated for the carbon di-
oxide increase and world temperatures
began to fall.
The total magnitude of these
changes in world or hemispheric mean
temperature is not impressive — a
fraction of a degree. However, the
difference between glacial and non-
glacial climates is only a few degrees
on the worldwide average.
Actually, it is not the mean tem-
perature of the earth that is impor-
tant, but rather the circulation pattern
of the atmosphere. This is stronglv
dependent on the temperature differ-
ence from the tropics to the poles.
The same man-modifiable factors that
affect the mean temperature of the
globe-albedo and carbon dioxide —
even if applied uniformly over the
globe — will have the effect of chang-
ing the meridional temperature gradi-
ent and thus the circulation pattern
and resultant weather pattern. It is
this change of pattern that is of prime
concern. Dzeerdzeerski in the Soviet
Union, Kutzbach in the United States,
and Lamb in England have all pro-
duced different kinds of evidence that
the circulation patterns have changed
in the past two decades. In turn, the
local climates show change — some
regions wetter, some drier, some
colder, some warmer — though some
remain unchanged.
The most striking changes have
been where the effects of the change
are cumulative, such as the slightly
changed balance between evaporation
and precipitation in East Africa which
has caused the level of great lakes
such as Victoria to rise markedly.
Another case is the balance between
ice wastage and production that has
changed enough in the last decade to
bring drift-ice to the Icelandic shores
to an extent unknown for a century.
It would be most useful to know what
the cumulative ecological effect of
these local or regional changes might
be. Since biological selection in re-
sponse to environmental changes usu-
ally requires a number of generations
to show the total effect of the change,
it is probably too soon to know the
total ecological impact of the present
change. Here we can only look to the
past to see what is possible.
The Lesson of History
The advent of radiocarbon dating
has given a new dimension to the
study of the variety of paleobotany
known as palynology. It is now pos-
sible to put an absolute time-scale on
the record of environmental change
contained in the pollen assemblages
recovered from bogs and lake sedi-
ments. In the context of the present
discussion, the most startling result
is the rapidity with which major envi-
ronmental changes have taken place.
If we examine the most carefully
studied and best-dated pollen profiles,
we find that the pollen frequencies
often show a quasi-exponential change
from, for example, an assemblage
that might indicate boreal forest to an
assemblage typical of mixed hard-
woods. Calling the time required for
half the change to occur the half-life
of the transition, it appears that such
major changes in vegetation may have
half-lives of a couple of centuries or
less. (Greater specificity must await
analyses with much finer time-resolu-
tion than has been generally used.)
Since the plants integrate the climate,
the half-life of the climatic change
must be shorter still!
With the agricultural land use of
the world still reflecting the climatic
pattern almost as closely as the native
vegetation did, a major shift in cli-
matic pattern within a century could
be disastrous. Unlike the past, migra-
tion into open lands is not possible:
there are none, and forcible acquisi-
tion of agricultural land with a favor-
able climate is not acceptable. Only
in a few nations would a combination
of regional variety and advanced tech-
nology allow an accommodation to a
major climatic change.
What We Need To Know
Faced with the possibility that we
are well into a climatic change of ap-
preciable magnitude, of man's mak-
ing, there appear a number of ques-
tions to which answers are urgently
needed.
Since in the past there have been
rapid changes in climate due to natural
causes, such as major changes in vol-
canic activity, what is the probability
of increased volcanism in the next few
decades adding to the pollution of the
atmosphere made by man and thus
speeding up the present climatic
change?
How far will the present climatic
change go? It appears that the change
from a glacial climate to a nonglacial
climate occurred with great rapidity.
Would the opposite change occur as
fast? What chance is there, on a rela-
tively short time-scale, to control the
sources of turbidity?
72
CAUSES Ol CHANGE
If we have reverted to the climate
characteristic of the early 1800's, what
displacements in the world agricul-
tural pattern will occur in the next
decade?
The answers to these and a host of
related questions will require a much
more sophisticated knowledge of cli-
mate and the man-environment sys-
tem than we now possess. Time is
short and the challenge to science is
clear.
Environmental Change in Arid America
One of the great controversies in
ice-age paleoecology is how to explain
the virtually simultaneous coast-to-
coast extinction of large mammals in
North America around 11,000 years
ago. We know, for example, that ele-
phants once existed even in the pres-
ently arid lands of the West. Paleon-
tologists have commonly recovered
the bones of Mammuthus columbi in
arid America, along with bones of
other extinct large mammals, includ-
ing horses, camels of two extinct
genera, extinct bison, and ground
sloth.
Did the climate change suddenly?
Fossil elephants and the like inevitably
provoke visions of a wetter climate
and a more productive ecosystem
than today's arid land will support.
But the fossil-pollen record has indi-
cated otherwise.
Fossil Pollen and
Other Forms of Evidence
The technique of fossil-pollen anal-
ysis has proved of unique value in
determining what the vegetation and,
by implication, the primary produc-
tivity of arid America must have been
during the period when this region,
along with the rest of the continent,
supported large numbers of native
large mammals.
Pollen is a very popular fossil be-
cause it is produced in quantity by
certain plants and, thanks to its acid-
resistant outer wall or shell, is pre-
served in many types of sediments.
Unlike fossils of larger size, pollen is
usually dispersed evenly throughout
a deposit rather than aggregated in
one or a few distinct beds. Under
relatively uniform sedimentation, as
determined by closely spaced radio-
carbon dates, one can estimate the
intensity of the local pollen rain
through time, as Davis has done in a
study of vegetation history at Rogers
Lake, Connecticut. Different vegeta-
tion zones shed different amounts of
pollen — a tundra much less than a
forest, for example. This is revealed
by the fossil pollen extracted through
hydrofluoric-acid treatment of lake
muds.
In many deposits, especially in arid
lands, absolute values cannot be esti-
mated. The relative amounts of the
dominant pollen types in a deposit can
be compared with the pollen content
of sediments presently being deposited
in areas of natural vegetation. Literal
interpretation of the relative pollen
percentage cannot be made — i.e., 10
percent pine pollen does not mean
that 10 percent of the trees in the
stand were pines. But the pollen
spectrum of all types identified in a
fossil count can be matched, through
computer programs or simple direct
comparison, with the pollen rain of
modern natural communities. This
method works especially well in west-
ern United States, where there are
extensive areas of relatively undis-
turbed vegetation. In this way, any
major or increasing number of minor
changes in vegetation through time
can be detected.
As opportunity allows, the fossil-
pollen record can be compared with
other forms of evidence. Macrofossil
remains of plants, including seeds and
leaves, are found in certain lake muds.
They have been reported in remark-
able abundance in ancient wood-rat
middens of certain desert regions by
Wells. The oldest rat's nests studied
by Wells are over 30,000 years in age,
essentially older than can be deter-
mined by the radiocarbon method.
The Climatic Record of
Western America
The fossil record of radiocarbon-
dated deposits covering the last 30,000
years in western America indicates an
initial cool, dry period becoming
colder and wetter by 20,000 to 16,000
years ago. At this time, there were
ponderosa-pine parkland and pinyon-
juniper woodland at elevations about
3,300 feet below their present lower
limits on western mountains. The fate
of prairie, both short and tall grass-
land, is unknown. The present prairie
region was occupied by spruce in the
north and pine in the south. This
suggests that arid America, like other
regions, was affected by the late
Pleistocene cooling associated with ice
advance over Canada.
Around 12,000 years ago the cli-
mate changed rather rapidly, becom-
ing warmer and drier, until conditions
were only slightly cooler and wetter
than now. Modern vegetation zones
have occupied their present positions,
with minor fluctuations, continuously
for the last 8,000 years.
Thus, the record shows that the
environment of western America in-
habited by mammoth, camels, native
73
PART III — CLIMATIC CHANCE
horses, and bison at the time of their
extinction 11,000 years ago was not
vastly different from what we know
at present. Why, then, did the ani-
mals die? Fossil pollen and other
evidence from the radiocarbon dating
of extinct Pleistocene faunas seem to
indicate that no environmental defects
will explain this phenomenon. One
must look elsewhere. And the only
new variable in the American ecosys-
tem of the late-glacial period is the
arrival of skilled Stone Age hunters.
These events of thousands of years
ago have major implications for mod-
ern-day range management.
Implications for Modern Range
Management
In part, the concept of the West as
a "desert" is based on the fact that
grass production is indeed quite low.
But the dominant woody plants found
across the one million square miles of
western America — the creosote bush,
sagebrush, cactus, and mesquite — do
yield large amounts of plant dry-
matter annually. Primary productiv-
ity data on these western shrub com-
munities are less abundant than one
might wish. Nevertheless, such data
as do exist indicate that shrub com-
munities in southern Arizona may
yield 1,400 kilograms per hectare a
year, considerably more than adjacent
grassland under the same climate (12
inches of precipitation annually).
Observers have overlooked or writ-
ten off this annual production, per-
haps because it is often avoided by
domestic livestock. Indeed, fifty years
of range management in the West has
been aimed at destroying the woody
plants to make way for forage more
palatable to cattle. The effort has
been singularly futile and should be
abandoned.
The Future of Western Meat-Pro-
duction — The dilemma faced by the
range industry in arid America is that
beef can be produced faster, more
efficiently, and at less expense in the
southeast or in feedlots. If this fact
is accepted, one can make a case for
keeping large areas of arid America
as they are, at least until much more
is known about primary production of
the natural communities and until
some value for Western scenery can
be agreed upon. Some large, wealthy
ranchers have already recognized this
and have disposed of their cattle.
More should be encouraged to do so.
If a meat-producing industry is to be
established in the marginal cattle
lands in the West, it should be based
on new domestic species, animals that
are better adapted to arid environ-
ments than cattle and that are adapted
for efficient browsing rather than
grazing.
Potential New Domesticates — One
obvious source for potential new
domesticates is Africa, where arid
ranges that barely sustain cattle are
supporting thrifty herds of wilde-
beest, kongoni, zebra, giraffe, and
kudu. In size and general ecology, the
African species bear at least general
resemblance to the extinct Pleistocene
fauna of the Americas. They did not
invade the New World during the ice
ages because they failed to range far
enough north to be able to cross
the Bering Bridge, the only natural
method of intercontinental exchange
open to large herbivores. Many natu-
ral faunal exchanges of arctic-adapted
herbivores did occur over the Bering
Bridge in the Pleistocene. Some, but
not all, of the invaders re-adapted to
warmer climates of the lower latitudes.
In summary: (a) Studies of fossil
pollen and other evidence of the last
30,000 years reveal no environmental
defects that might explain the extinc-
tion of many species of native New
World large mammals 11,000 years
ago. (b) The only known environ-
mental upset at the time of large ani-
mal extinction was the arrival of Early
Man. (c) The cattle industry of west-
ern America is marginal, being main-
tained for reasons of its mystique, not
for its economics, (d) If a more pro-
ductive use of the western range is
desirable, experiments with other
species of large mammals should be
begun now, as indeed they have been
on certain ranches in Texas, New
Mexico, Mexico, and Brazil.
74
PART IV
DYNAMICS DFTHE
ATMOSPHERE-OCEAN
SYSTEM
1. OCEANIC CIRCULATION AND OCEAN-
ATMOSPHERE INTERACTIONS
Oceanic Circulation and the Role of the Atmosphere
The ocean circulation is one of the
primary factors in the heat budget of
the world. The circulation is impor-
tant not only internally to the ocean
but also to the overlying atmosphere
and, indeed, to the climate of the
entire earth. Together the sea and
the air make a huge thermal engine,
and it is not possible to understand
either without having some compre-
hension of the other. Any studies of
ocean circulation must inevitably in-
volve this coupling with the atmos-
phere.
The Present State of Understanding
Studies of ocean circulation have
progressed a long way in the past
fifty years. Measurements of the
characteristics of the ocean at great
depths have produced at least a gen-
eral sense of the major deep circula-
tions. And extensive theoretical de-
velopments over the same period have
given us some glimmering as to why
the circulations are what they appear
to be.
Ocean Variability — Both the ob-
servational and theoretical studies
have dealt mostly with a steady-state
ocean or the long-term mean of an
ocean. (See Figure IV-1) During the
past few years, however, some data
have been accumulated that allow us
to speculate a bit about the variability
of the ocean. Like mean circulation,
variability is closely coupled to the
atmosphere, and variations in ocean
circulation may lead to, or stem from,
variations in atmospheric phenomena.
For example, one of the critical parts
Figure IV-1 — SEA-SURFACE TEMPERATURE
AVERAGE
EMPERATURE
IN C
NORMAL
COLDER-
I I £
WARMER
The figure shows sea-surface temperatures represented as deviations from global
average values of the sea-surface temperature. The global average value for each
5° latitude band is marked at the right-hand edge of the world map. Note the extent
of the cold equatorial water in the Pacific (from the coast of South America westward
halfway across the Pacific) and the warm water west and north of the United
Kingdom.
77
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
of the heat engine is the Norwegian
Sea, an area where warm saline sur-
face water from the Gulf Stream is
cooled by contact with the atmos-
phere, made dense, and returned to
the open Atlantic as dense deep water
in such quantity as to create a recog-
nizable subsurface layer extending
throughout the Atlantic, Antarctic,
Indian, and Pacific oceans. In this
case, the power to drive this thermo-
haline engine comes from heat ex-
change with the atmosphere.
Warming of the surface waters in
low latitudes and cooling in high lati-
tudes creates easily recognizable ef-
fects on the circulation of the ocean.
The effect of this exchange on the
atmosphere is equally important, not
just locally — in that the coast of
Norway remains ice-free — but also
in the larger sense of general effects
on the world atmospheric climate.
The budget of this heat exchange and
the details of its various expenditures
must be learned if the earth's climate
is to be understood. Seasonal and
nonseasonal variations of the heat
exchange, and their causes and ef-
fects, must be studied.
The Gulf Stream is both a cause
and an effect of this exchange. It
would exist in any case as a conse-
quence of the wind-driven circulation
in the trade-wind and westerlies areas,
as do, in a weaker form, its South
Atlantic, North Pacific, and South
Pacific counterparts. (The heat and
water sink of the far North Atlantic
requires a vaster flow in the Gulf
Stream than in the other western
boundary currents.) But variations in
the strength of the Gulf Stream may
be either causes or consequences of
variations in heat exchange in the
Norwegian Sea. Although the effects
of these variations may be severely
damped by the time the waters enter
the immense reservoir of the abyssal
ocean, there is no certainty that their
effects on the far reaches of the ocean
are negligible.
Some of the most interesting varia-
tions yet observed in the ocean are
in the North Pacific, where bodies of
surface water thousands of miles in
diameter remain warmer or colder
than their seasonal means for periods
ranging from three months to over a
year. Such features seem to be char-
acteristic of the North Pacific. Thus,
a typical map of surface temperature
is not one that is very near the norm
everywhere, with many small highs
and lows; instead, the whole North
Pacific may consist of three to five
large areas of deviant temperature.
Such features have been noted only
in the past fifteen years. They are
beginning to receive the attention of
meteorologists, as well as oceanogra-
phers, since their consequences for
the atmospheric climate cannot be
discounted in attempting to under-
stand and predict the world's weather.
Prediction — Our present under-
standing of the ocean is barely suffi-
cient to account for the major cir-
culations in a general way. Some
preliminary attempts are now being
made to predict specific features of
ocean behavior, most of them being
based on the persistence of deviations
from the mean. That is, if an area
shows an abnormally high surface
temperature in one month, this anom-
aly is apt to endure or persist for
several months more and to diminish
to the norm slowly. Strictly speaking,
this is not prediction but merely the
extrapolation of a present feature.
More ambitious predictions are being
contemplated, but they are still in
very early stages.
Advances in Instrumentation
Devices to measure ocean currents
have improved greatly over the past
ten years. They have been used to
monitor changes in position of the
Gulf Stream, to measure its deep
flow, and to investigate some of the
principal inferences about deep cir-
culation in the Pacific and Atlantic
oceans. Considerable improvement
has also been achieved in instruments
for measuring water characteristics.
Moored buoys of various kinds
have been developed for deep-water
use within the past decade. They are
used for monitoring certain character-
istics of the ocean and atmosphere,
including wind, air, and sea tempera-
ture, subsurface temperature, waves,
and, possibly, water velocity. These
measurements can either be recorded
and recovered by vessels or trans-
mitted immediately by radio to ap-
propriate shore bases.
The future may see interrogation
and retransmission of signals by satel-
lite. The advantages of such monitor-
ing stations would include relatively
inexpensive operation (compared to
weather ships) and the ability to
gather data from regions that are out-
side normal shipping lanes but may
be extremely pertinent to ocean and
weather studies.
Deficiencies in the Data Base
The data base for study of the
ocean consists of measurements of
water characteristics in various loca-
tions and depths at different times
and measurements of currents, waves,
tides, and ocean depths. In some
areas and some seasons, this data
base is adequate for a long-term mean
to be established; it is not continuous
enough in time, however, to allow for
adequate study of variations from the
long-term mean. In other areas and
seasons, the data base barely exists.
High-latitude areas in winter have
hardly been explored. Our knowl-
edge of the deep arctic is extremely
limited. Some few winter data are
available from the antarctic region.
The deeper parts of the ocean may be
better represented in the present data
base than the surface parts, since the
deeper parts show less time-variation
than the upper layers.
Other parts of the data base in-
volved in investigating ocean circu-
lation include atmospheric-pressure
observations and wind measurements,
air temperature and the like. These,
78
OCEANIC CIRCULATION AND OCEAN-ATMOSPHERE ITONS
too, are limited both in time and
space. Major shipping lanes are fairly
well measured in many seasons.
Among the more systematically meas-
ured areas are the North Sea, the
California Current system, and the
Kuroshio Current. But data from the
areas that ships avoid, either because
of bad weather conditions or because
they do not represent profitable ship
routes, are generally sparse. Not only
is the arctic poorly represented even
with atmospheric information, but
also the South Pacific and large parts
of the South Atlantic. Very few areas
in the world are represented by a
data base sufficient to allow for sea-
sonal and nonseasonal variations.
Numerical models of the ocean are
also still in an early stage of develop-
ment.
What is Needed
A proper understanding of air-sea
interchange and of deep flow are
among the most urgent tasks of oce-
anic circulation research. We need to
determine which data are critical, ob-
tain them, and use them in mathe-
matical modeling of the ocean. Topics
of practical importance to man, re-
quiring urgent study, include fisheries
production in the world ocean; this is
related to ocean circulation, since the
latter controls the availability of plant
nutrients.
Better understanding of the Arctic
Ocean is crucial to proper evaluation
of its possibilities as a commercial
route for surface vessels or subma-
rines. Better knowledge of the deep
circulation and the rates of exchange
of ocean water — both from the sur-
face to the bottom and from the
deeper parts of one ocean to the
deeper parts of another — is particu-
larly important in the light of new
concerns over contamination and pol-
lution. While the ocean can act as a
reservoir to absorb, contain, and re-
duce much of the effluent now being
produced, it is not of infinite capacity
nor can it contain materials indefi-
nitely without bringing them back
onto the surface.
Time-Scale — It is not possible to
lay out a time-scale for many of the
things that must be investigated. For
the problem of describing the mean
ocean, another ten or fifteen years
might be sufficient. In that period of
time, it would be feasible to collect
the additional data needed without
substantially expanding the facilities.
In order to accomplish this, however,
the various institutions capable of
carrying out the requisite measure-
ments would have to devote a greater
part of their time to this subject —
and this may not be desirable.
Developing a data base to study
the time-variable ocean is a different
sort of problem. Since our under-
standing of the nature of time-varia-
tions is still in a primitive stage, we
must first learn how to observe the
phenomena and then begin a system-
atic series of observations in the ap-
propriate places. Progress has been
made in learning how to do this from
buoy deployments in the Pacific and
Atlantic oceans. These are prelimi-
nary, however, and must be greatly
augmented before we can really un-
derstand even the scale, much less
the nature, of the anomalies being
observed. Understanding of this kind
usually advances step by step from
one plateau to another, but the steps
are highly irregular both as to height
and duration, and a feasible time-
scale cannot be estimated.
Necessary Activity — On the one
hand, the scale of the problems dis-
cussed here suggests large-scale,
large-area, heavily instrumented re-
search carried out by teams of in-
vestigators. On the other, the history
of ocean circulation research has
shown that some of the greatest con-
tributions were made by individuals
— e.g., Ekman transport, Stommel's
westward intensification, Sverdrup
transport. A balance is required be-
tween large-scale programs compa-
rable to the space program and indi-
vidual small-scale projects.
One of the first needs is to train
people able to work on problems of
both the ocean and the atmosphere.
The two fields have been far too sepa-
rated in most cases. People trained
in mathematics and physics are avail-
able, but the average student finds it
difficult to acquire a working back-
ground in both the oceanic and at-
mospheric environment; indeed, many
people trained in physics and mathe-
matics have limited backgrounds in
either environment, relying on theory
without adequate knowledge of the
structure of the two systems.
On Predicting Ocean Circulation
Nonspecialists tend to think of
ocean circulation systems as being
primarily a matter of geographical
exploration. We are not going to dis-
cover many new undercurrents, how-
ever. Nor will simple-minded "moni-
toring" of ocean currents teach us
much. Twenty years of looking for
— and not finding — relations be-
tween changes in patterns of applied
wind stress and the total transports
of currents like the Gulf Stream
where it passes through the Florida
Straits warn us that the chain of
cause and effect in the ocean is rather
79
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
complicated and that the primary
problem is to make more profound
our understanding of the ocean as a
hydrodynamical phenomenon.
What We Know — and Don't Know
It has been pointed out that there
has been a really effective growth of
understanding of ocean surface waves
only in the last decade. And ocean
surface waves are probably the most
easily observable and dynamically
linear of ocean phenomena. Internal
waves and oceanic turbulence are not
so easily observable, and treatments
of these phenomena are a thin tissue
of preliminary theory largely unsup-
ported by observation. Studies limited
to rather high-frequency phenomena
actually represent the kind most
nearly duplicable in the laboratory.
There is a small body of theory
concerning oceanic circulation, but it
deals only with the climatological
mean circulation. The role of medium-
scale eddy processes in ocean circula-
tion is completely unknown, although
current measurements indicate that
they can be very important — as, for
example, they are in the general circu-
lation of the atmosphere. A two-
pronged development of mathematical
modeling and fairly elaborate field in-
vestigation is going to be necessary to
develop much further our under-
standing of the hydrodynamical in-
teraction of these eddies and the
mean circulation. (A working group
of the Scientific Committee on Ocean
Research of the International Coun-
cil of Scientific Unions recommended
a "Mid-Ocean Dynamics Experiment"
(MODE).) Considering the three-
dimensional detail of velocity struc-
ture and its development in time that
such a measurement program will
entail, it seems clear that a major
input from the engineering commu-
nity will be needed.)
Technological Limitations
Oceanography is not presently
competent technologically to tackle
the tasks of measurement that are
necessary in trying to tinravel the
dynamical features of large-scale mo-
tions. The difficulty is simply that one
needs to map variables like velocity
rather densely in large volumes (per-
haps 2 miles deep and 300 miles on a
horizontal side) for rather long pe-
riods (perhaps a year) with sufficient
accuracy that reliable statistics can be
calculated for complicated functions
like triple correlation products. Many
different modes of motion are occur-
ring simultaneously, and we need to
be able to separate one mode from
another in order to compute interac-
tions. Therefore, a great variety of
arrays of sensors need to be arranged
in different configurations and on
different scales for gathering the kind
of data required from the ocean.
Some test portions of the ocean will
need to be heavily instrumented in a
manner more sophisticated than pres-
ent small-scale observational opera-
tions can achieve. It is safe to say
that solutions of problems of internal
waves, the general circulation and
eddy processes, and such important
local processes as coastal upwelling
are simply going to have to wait until
major new instrumental arrays be-
come available.
There is a limit beyond which in-
ferior technique cannot go. It needs
to be made very clear what a helpless
feeling it is to be on a slow-moving
ship, with a few traditional measuring
techniques like water bottles and
pingers on hand, trying to keep track
of a variable phenomenon like an
eddy that won't hold its shape. A
faint idea of the elusiveness of the
phenomenon can be conveyed to any-
one who has tried to pick up mercury
with his fingers or who has watched
a teacher trying to keep track of her
pupils on an outing to a public park.
But the ocean environment is so much
larger, so much harder to see, that we
don't bring many of "our children"
home. Measurement in large-scale
ocean physics illustrates this limit
very well. Further theoretical devel-
opment is simply going to have to
wait upon adequate measurement
technique. The theoretical difficulties
are not serious; mathematical model-
ing can be worked by machine once
sufficient insight has been gained as
to what is actually going on in the
ocean.
The Need for Mathematical Models
Some advances in climate control,
pollution evaluation, and numerical
weather forecasting might be achieved
simply by extending present land-
based meteorological networks into
the ocean by means of buoys. Per-
haps a superficial knowledge of tem-
perature on a coarse grid in the upper
100 meters of the ocean will be useful
to meteorologists. But this will not
provide the basis for a quantitative,
rational, ocean-prediction system.
In order to be able to predict the
mechanism of the ocean it is neces-
sary to have numerical-mathematical
models that have been verified by
comparison with actually observed
case histories of oceanic motion. Be-
cause there are several modes of such
motion, these experiments or com-
parisons have to be made on several
different scales. But to date they have
not been made. They are beyond our
technical means.
Actually, it is too early to try to
design an oceanic monitoring system;
some experimental measuring systems
are needed first — aimed squarely at
providing input for mathematical
numerical modeling of the basic hy-
drodynamical processes at work. Suc-
cessfully tested models could evolve
into successful prediction schemes.
If sufficient resources were mus-
tered to start a good crew of instru-
ment engineers on a sample program
of measurement, sufficient progress
might be made in carrying out one
sample comparison of theory and
observation to catalyze progress on
the other necessary experiments. One
has the feeling that the science is
locked in a dead-center position, and
that a mighty shove is going to be
needed to get it rolling.
80
OCEANIC CIRCULATION AND OCEAN-ATMO1 1 IONS
Hydrodynamic Modeling of Ocean Systems
Waves and currents in the ocean
can be organized into many different
categories depending on horizontal
dimension and the time-scale of vari-
ability. Some of these categories are
strongly interconnected, others al-
most independent. In Figure IV-2 an
attempt is made at classification, along
with an indication of the principal
ways in which each phenomenon has
an impact on human activities. (The
emphasis in this outline is on ocean-
circulation phenomena; surface waves,
tides, and storm tides are treated only
briefly, although thev are admittedly
important subjects from the stand-
point of practical disaster-warning
systems.)
Present Status
Wind Waves and Tidal Waves —
The numerical models presently used
to predict surface waves are essentially
refinements of earlier operational
models developed by the U.S. Navy;
they have proved valuable to ship-
ping. New computer models, how-
ever, allow a much more detailed in-
corporation of the latest experimental
and theoretical advances in the study
of wave generation. Furthermore, or-
biting satellites may soon be able to
provide a good synoptic picture of the
surface sea state all over the globe.
Given an accurate weather forecast,
computer models would then be able
to predict future sea states. Indeed,
it may turn out that the ultimate limi-
tation to wave forecasting will involve
the accuracy of the weather forecast
rather than the wave-prediction
model itself.
Operational models for predicting
tidal waves (tsunamis) have been de-
veloped for the Pacific, where the
danger of earthquakes is greatest. As
soon as the epicenter of an earth-
quake is located by seismographs, the
model can predict the time a tidal
wave will arrive. Such warning sys-
tems are being developed by the
National Oceanic and Atmospheric
Administration (NOAA) and the
Japanese Meteorological Agency.
Storm Surges and Tides — Most of
the research in developing numerical
models to predict storm tides has
been carried out in Europe, in con-
nection with flooding in the North
Sea area. In the United States, storm
surges caused by hurricanes ap-
proaching the Gulf Coast have gener-
ated the most interest. The results of
these model studies appear promising.
Graphs and charts based on the
model calculations may be used by
Weather Service forecasters in mak-
ing flood warnings. The models will
also be useful in the engineering de-
sign of harbor flood-walls and levees.
In time, computer models will prob-
ably replace the expensive and cum-
bersome laboratory models of harbors
now used by coastal engineers.
Figure IV-2 — CLASSIFICATION OF WAVES AND CURRENTS
Time-Scale
Local
Intermediate
Global
Short
(minutes)
Surface Waves
(shipping,
shore erosion,
offshore drilling)
Tidal Waves (tsunamis)
(safety of shore areas)
Intermediate
(hours/days)
Ocean Turbulence
and Mixing
(pollution, air-sea
interaction
Storm Surges
(safety of
shore areas,
hurricane damage)
Tides
(navigation)
Long
(months/years)
Near-Shore
Circulation
(pollution)
Circulation of
Inland Seas
(Great Lakes
pollution, polar
pack-ice models)
Circulation in
Ocean Basins
(long-range weather
forecasting, fisheries,
climatic change)
The chart classifies waves and circulations as functions of time and distance.
81
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
Ocean Circulation — Over the past
decade, three-dimensional numerical
models for calculating ocean circula-
tion have been developed by the So-
viet Hydrometeorological Service and
NOAA. The methods used are sim-
ilar to those of numerical weather
forecasting. Given the flux of heat,
water, and momentum at the upper
surface, the model predicts the re-
sponse of the currents at deeper
levels. The currents at deeper levels
in turn change the configuration of
temperature and salinity in the model
ocean.
Although active work in develop-
ing these models is being conducted
at several universities, the only pub-
lished U.S. calculations are based
on the "box" model developed at
NOAA's Geophysical Fluid Dynamics
Laboratory. This model allows the
inclusion of up to 20 levels in the
vertical direction and a detailed treat-
ment of the bottom and shore con-
figuration of actual ocean basins.
Cox's calculation of the circulation
of the Indian Ocean is perhaps the
most detailed application yet at-
tempted with the NOAA "box"
model. Using climatic data, it was
possible to specify the observed dis-
tribution of wind, temperature, and
salinity at the surface as a function of
season. The model was then able to
make an accurate prediction of the
spectacular changes in currents and
upwelling in response to the changing
monsoons that were measured along
the African coast during the Indian
Ocean Expedition of the early 1960's.
Application of the Model to Prac-
tical Problems — The numerical mod-
els designed for studying large-scale
ocean circulation problems can be
modified to study more local circula-
tion in near-shore areas or inland
seas such as the Great Lakes. Thus,
numerical models may be useful for
the many problems in oceanography
in which steady currents play a role.
A partial list includes: (a) long-range
weather forecasting; (b) fisheries fore-
casting; (c) pollution on a global or
local scale; and (d) transportation in
the polar ice-pack.
Needed Advances
The Data Base — Standard oceano-
graphic and geochemical data provide
a fairly adequate base for modeling
the time-averaged, mean state of the
ocean. The data base for modeling
the time-variability of the ocean is
extremely limited, however. Infor-
mation on large-scale changes in
ocean circulation as well as the small-
scale variability associated with mix-
ing in the ocean have not been gath-
ered in any comprehensive way.
Future progress in ocean modeling
will depend on more detailed field
studies of ocean variability. Such
studies will establish the data base
for the formulation of mixing by
small-scale motions which must be
included in the circulation model.
Information on large-scale variability
will provide a means for verifying the
predictions of the models.
Technical Requirements — The
most promising approach appears to
be the different arrays of automated
buoys that have been proposed as
part of the International Decade of
Ocean Exploration (IDOE) program.
Coarse arrays covering entire ocean
basins, as well as detailed arrays for
limited areas, will be required.
Another technical requirement for
ocean modeling is common to a great
many other scientific activities: the
steady development of speed in elec-
tronic computers and the steady de-
crease in unit cost of calculations.
Manpower Training — Numerical
models of currents have now reached
a point where they can be of great
value in the planning of observational
studies and the analysis of data col-
lected at sea. The models can be used
in diagnostic as well as predictive
modes. This is particularly true of
the buoy networks proposed as part
of the IDOE. In order to do this,
however, more oceanographers will
need to be trained to use the numeri-
cal models and to carry out the com-
putations. This action will have to
be taken quickly if numerical models
are to have much signficance in IDOE
programs.
Application of Ocean Modeling
in Human Affairs
As pointed out by Revelle and
others, a large fraction of the added
carbon dioxide (CO-) generated by
the burning of fossil fuels is taken
up by the oceans. However, few
details are known concerning the
ocean's buffering effect and how long
it will continue to be effective. The
ability of the ocean to take up CO-
depends very much on how rapidly
surface waters are mixed with deeper
water. More detailed studies of geo-
chemical evidence and numerical
modeling are essential to get an un-
derstanding of this process. A start
in numerical modeling of tracer dis-
tributions in the ocean has been
made by Veronis and Kuo at Yale
University and Holland at the NOAA
Geophysical Fluid Dynamics Labora-
tory.
Another urgent task is to make an
assessment of the effect of CO- and
particulate matter in the atmosphere
on climate. Present climatic knowl-
edge does not allow reliable quan-
titative predictions of the "green-
house effect" due to CO- or the
screening out of direct radiation by
particulate matter. Published esti-
mates have been based on highly
simplified models that treat only the
radiational aspects of climate. But
no climate calculation is complete
without taking into account the cir-
culation of both the atmosphere and
the ocean. Some preliminary climatic
calculations have been carried out
with combined numerical models of
the ocean and atmosphere. But
greater effort is required to develop
82
OCEANIC CIRCULATION AND OCEAN-ATMOSPHERE INTERACTIONS
more refined ocean models if these
climatic calculations are to be reliable
enough to be the basis for public
policy decisions on pollution control.
Time-Scale of Significant Ad-
vances — Since published papers on
three-dimensional ocean circulation
models have only recently begun to
appear, rapid development should
continue for at least another five
years along present lines. In that
time, ocean models should have
reached about the same level of
development as the most advanced
atmospheric numerical models today.
Within five years, at least the feasi-
bility of application of numerical
modeling to small- and large-scale
pollution studies, long-range weather
forecasting, and hydrographic data
analysis should be well established.
Another five years will probably be
required to work out standard pro-
cedures for using numerical ocean
circulation models in these applica-
tions.
Effects of Antarctic Water on Oceanic Circulation
Except for a relatively thin (slightly
less than one kilometer) warm surface
layer in the tropics and subtropics,
the ocean is basically cold and fairly
high in dissolved oxygen content.
Ninety percent of the ocean is colder
than 8 centigrade, with an oxygen
content generally from 50 to 90 per-
cent of the saturation level. This
warm surface layer, because of its
high stability, acts as an impervious
cap over the cold abyssal water,
blocking renewal (by the usual tur-
bulent transfer methods) of the oxy-
gen that has been consumed by
various biological processes.
warm and low-oxygen-content cir-
cumpolar deep water (CDW) slowly
flows southward and upward. Even-
tually, it reaches the near-surface
layers at the wind-produced Antarc-
tic Divergence. Here, the intense
thermohaline alteration resulting from
the sea-air interaction converts the
CDW into "antarctic surface water"
(AASW), which is cold (near freez-
ing, —1.6° to —1.9° centigrade)
and relatively fresh. Some of the
CDW is converted by more intense
thermohaline alterations due to ice
formation into a fairly dense con-
tinental shelf water. At certain times,
this shelf water drops to the sea floor
where, on mixing with additional
CDW, it forms the "antarctic bottom
water" (AABW); neither the times
nor the exact locations of the vertical
motion are adequately known. The
AABW has worldwide influence. It
reaches far into the northern hemi-
sphere in the western Atlantic and
Pacific oceans.
Though we do not know how the
shelf water is produced, three meth-
ods appear to be likely: (a) sea-ice
formation; (b) freezing, melting, or
a combination of these at the floating
Why, therefore, is the bulk of the
ocean so cold and highly oxygenated?
In studying the relationship of tem-
perature to salinity in the cold abyssal
waters of the world ocean, one is
struck by its similarity to that found
in antarctic waters. This suggests
that the oceanographic processes oc-
curring in antarctic waters influence,
in a direct way, the physical and
chemical properties of much of the
ocean's abyssal water. One may
think of the antarctic region as a
zone in which the abyssal waters can
"breathe," renew their oxygen sup-
ply, and release to the atmosphere the
heat received at more northern lati-
tudes.
The Antarctic Water Masses
Figure IV-3 — ANTARCTIC WATERS AND THEIR CIRCULATION
POLAR
FRONT
ZONE
ANTARCTIC
DIVERGENCE
ZTlUE^NTARCTirr^ \ A /?/ "^AiTARCTIC
IURFACI
WATER
h(>'
ICE SHELF
SS™E -^^7i~<i
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The basic circulation pattern along
a north-south plane in antarctic wa-
ters is shown in Figure IV-3. The
This figure shows the position, circulation, and interaction of the several water
masses found in the antarctic region.
83
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
base of the extensive ice shelves of
Antarctica; (c) rapid cooling and evap-
oration resulting from the outbreaks
of cold, dry antarctic air masses.
Recently, a fourth method was pro-
posed which is based purely on
molecular exchange of heat and salt
between a warm salty lower layer
and a cold fresh upper layer. Which
of these methods is the dominant one
is not known. Method (a) has gen-
erally been considered the key
method; however, recent studies
show that method (b) may be most
important. It is probable that all
the methods are active to a varying
degree, depending on the location,
and a variety of AABW types are
formed.
The AASW flows slowly north-
ward (see Figure IV-3); on meeting
the less dense sub-antarctic water
(near 55" S.), it sinks, contributing
to the "antarctic intermediate water"
(AAIVV). The cold, relatively fresh
AAIW flows northward at depths of
nearly one kilometer. It reaches the
equator in the Indian and Pacific
oceans and up to 20 N. in the
Atlantic Ocean.
The zone where the AAIW forms
is called the "polar front zone," or
Antarctic Convergence. The proc-
esses occurring within the zone are
not understood; even the concept of
a "convergence" process is question-
able. The structure and position of
the polar front zone varies with time.
How, and in what frequency, and
how it influences the AAIW forma-
tion are not known at all. The polar
front zone should be subjected to
much study in the coming years.
It is of major importance to the
overturning process of ocean waters
and to climatic characteristics of the
southern hemisphere and perhaps the
world. The only way to study this
feature effectively is by multi-ship
expeditions and/or time-series meas-
urements from numerous anchored
arrays of instruments.
Exclmngc of Water Masses — From
salt studies, the general rate of me-
ridional exchange has been deter-
mined. The CDW southward trans-
port is 77 million cubic meters per
second, of which only 15 million cubic
meters per second have been derived
from the sub-arctic regions (mainly
from the North Atlantic). The rest is
the return flow from the two north-
ward antarctic components (AAIW
and AABW). The CDW also brings
heat into the antarctic region. It is
calculated that 14 to 19 kilogram
calories per cm2 per year are released
into the atmosphere by the ocean.
This has a great effect in warming
the antarctic air masses and, hence,
in modifying the influence of Antarc-
tica on world climate.
The exchange of CDW for AAIW
and AABW has the important result
of taking out the warm, low-oxygen-
ated water and replacing it with cold,
high-oxygen-content water. Were it
not for this, the abyssal waters would
warm considerably by geothermal
heating and downward flux of heat
across the thermocline. They would
also become devoid of oxygen by
organic decomposition.
Need for More Information
Though the gross features of the
circulation pattern can be found, we
do not know enough detail about
the process of conversion of CDW
into the antarctic water masses. In
what regions does this conversion
take place? Is it seasonal or does it
vary with another frequency? By
what methods is the CDW converted
into antarctic water masses?
To accomplish these tasks, long
time-series measurements of currents,
temperature, and salinity are needed
along the continental margins of Ant-
arctica and within the polar front
zone. Multi-ship expeditions and
satellite observations would also be
useful in studying time-variations of
the water structure. Geochemical
studies of the isotopic makeup of the
ice and sea water are necessary to
yield information as to "residence"
times within water masses and in-
sight into methods of bottom-water
production.
The antarctic waters are also of
importance in that they connect each
of the major oceans via a circum-
polar conduit. The rate of the cir-
cumpolar flow is not known, though
recent studies indicate a volume
transport of well over 200 million
cubic meters per second, making it
the largest current system in the
world ocean. A program of direct
current observations is needed to
study the circumpolar current. Satel-
lite surveillance of drogues will be
a useful method to study the current
systems.
In short, scientists need to know
in more detail the methods, rates,
and location of the formation of the
antarctic water masses. They can
accomplish this task by hydrographic
and geochemical observations in cir-
cumpolar waters using modern tech-
niques. In addition, detailed time-
series observations would be needed
at particular points such as the Wed-
dell Sea, Ross Sea, the Amery Ice
Shelf, and other appropriate regions.
Tropical Air-Sea Rhythms
Tropical air-sea rhythms are best
seen in the time-series of air and
sea temperature at Canton Island,
an equatorial island in the Pacific
(2°48'S. 171°43'W.); this is the only
locality where temperature observa-
tions have been maintained uninter-
ruptedly over a long period, 1950
through 1967. However, there is now
no way of continuing this important
time-series because the Canton Island
observatory, with its modern equip-
84
OCEANIC CIRCULATION AND OCEAN-ATMOSPI :;
ment for aerological data-gathering,
was abandoned in September 1967
for economy reasons.
Air-sea data from near-equatorial
islands has great importance because
the sea temperature in such localities
is subject to fluctuations of much
greater amplitude than in the ad-
jacent trade-wind belts of either
hemisphere. As a consequence, the
heat supplied from the ocean to the
atmosphere near the equator becomes
the most variable part of the total
tropical ocean-to-atmosphere heat
flux, which in turn is the major con-
trol of the global atmospheric circu-
lation. It is, therefore, logical to
expect that ocean temperature fluc-
tuations near the equator will influ-
ence atmospheric climate outside of
tropical latitudes. This action by re-
mote control through the global at-
mospheric circulation is here referred
to as "teleconnections."
According to preliminary findings,
the teleconnections from the Pacific
equatorial air-sea rhythms are major
factors — perhaps, in many cases,
the dominant factor — in creating
rhythms of climatic anomalies any-
where on the globe. Hence, these
teleconnections must be understood
before climatic anomalies can be
predicted successfully.
General Characteristics
The following facts stand out from
the Canton Island record. (See Figure
IV-4)
1. Sea temperatures vary over a
greater range than air tem-
peratures.
2. In periods of cold ocean the
air is warmer than the sea,
whereas in periods of warm
ocean the air is colder than the
sea.
3. Heavy monthly rainfall occurs
only during periods of warm
ocean.
It is known from atmospheric ther-
modynamics that the heating of the
atmosphere over a tropical ocean
takes place mainly through the heat
of condensation within precipitating
cloud. Hence, the rainfall record is
also a record of the major year-to-
year variations of the atmospheric
heat supply from the ocean. Those
variations showed rhythms of about
Figure IV-4 — CANTON ISLAND DATA
CANTON ISLAND 2°48'S I7I°43'W
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The figure shows a time-series of monthly air and sea temperatures and monthly
precipitation amount as measured at Canton Island from 1950 through 1967.
85
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
two years' periodicity, especially dur-
ing the 1960's; at other times the
rhythms were less regular.
The mechanism of the equatorial
air-sea rhythms is illustrated in Fig-
ure IV-5, which shows that a six-
month, smoothed time-series of
atmospheric pressure in Djakarta,
Indonesia (6°S. 107 E.), exhibits the
same long-period trends as the sea-
surface temperatures measured at
Canton Island and by ships crossing
the equator at 165W. When the
barometric pressure in Djakarta is
lower than normal, the equatorial
easterlies heading for the Indonesian
low become stronger than normal;
this automatically intensifies the
Pacific equatorial upwelling and cools
the sea surface. The parallelism of
the time-series of Djakarta pressure
and Canton Island sea temperature
is thereby assured.
If wind profiles are observed along
the equator at two opposite phases
of the air-sea rhythm, as exemplified
by November 1964, with its cool
ocean and aridity, and November
1965, with its warm ocean and abun-
dant rainfall at Canton Island, it is
found that in November 1964 the
equatorial easterlies swept uninter-
ruptedly from South America past
Canton Island toward a deeper-than-
normal Indonesian low, whereas in
November 1965 they stopped short
of reaching Canton Island. The equa-
torial upwelling — a by-product of
the equatorial easterlies — extended
almost to Indonesia in November
1964, while being confined to a much
smaller area east of Canton Island
a year later. Concomitantly, the
equatorial rainfall was confined to the
neighborhood of Indonesia in No-
vember 1964; the following year it
expanded from the west to beyond
Canton Island, while Indonesia suf-
fered serious drought.
The propulsion of the air-sea
rhythms resides in the atmospheric
thermally driven equatorial circula-
tion over the Pacific, which has its
heat source (by condensation) in the
rising branch, and heat sink (by
radiative deficit insufficiently com-
pensated by scarce precipitation) in
its descending branch near South
America. The oceanic counterpart to
this atmospheric circulation is, in
part, the westward surface drift and
Figure IV-5 — WALKER'S "SOUTHERN OSCILLATION"
The diagram shows the similarities in trend ot the time-series of sea temperature
and pressure measured at and near the equator in the southern hemisphere. The
dotted curve that follows that for Djakarta is based on data from Singapore. The
rapid oscillations of the sea-temperature curve measured at the equator in 1958 and
1959 result from more frequent ship crossings — and hence a greater density of short-
period detail — rather than from any unusual natural activity.
the subsurface return flow and, addi-
tionally, the circulation consisting of
an upwelling thrust at the equator
and sinking motion to the north and
south of the equator. These ocean
circulations are wind-driven and in-
trinsically energy-consuming, but they
exert a powerful feedback upon the
atmosphere by slowly varying the
areal extent of warm water at the
equator and thereby varying the ther-
mal input for the global atmospheric
circulation.
In November 1964, when cool up-
welling water occupied almost the
whole Pacific equatorial belt, the at-
mosphere received less heat than in
November 1965, when the upwelling
had shrunk back into a smaller east-
ern area. Consequently, the tropical
atmosphere swelled vertically from
1964 to 1965. This swelling was
most conspicuous over the Pacific
at 160 W. longitude. Moreover, the
swelling of the tropical atmosphere
had spread all around the global
tropical belt between 1964 and 1965,
a global adjustment that is inevitable,
since pressure gradients along the
equator must remain moderate.
North and south of the swelling
atmosphere in the tropical belt, the
gradient of 200-millibar heights in-
creased from November 1964 to
November 1°65, which indicated
increasing westerly winds in the
globe-circling subtropical jet streams.
This can best be documented in the
longitude sector from the area of
Pacific equatorial warming eastward
across North America and the At-
lantic to the Mediterranean.
The corresponding change at sea
level could be seen most dramatically
over Europe, where the moving low-
pressure centers abandoned their
normal track by way of Iceland to
Scandinavia and, instead, in Novem-
ber 1965 moved parallel to the
strengthened subtropical jet stream
and invaded central and southern
Europe.
Other associated rearrangements
involved the arctic high-pressure sys-
86
OCEANIC CIRCULATION AND OCEAN-ATMOSPHL
tern, which in November 1965 was
displaced toward northern Europe
and, consequently, on the Alaskan
side of the pole left room for the
moving low-pressure systems from
the Pacific to penetrate farther north
than normal.
So much for a description of the
air-sea rhythms. Supporting evidence
is available from a few other case
histories. The motivation for con-
tinued research on the equatorial air-
sea rhythms is the desire to develop
skill in forecasting climatic anomalies.
Current Scientific Knowledge
The data base is, unfortunately,
scanty. As mentioned earlier, Canton
Island is the only place where a
continuous record of the near-equa-
torial air-sea interaction was main-
tained; even there, scientific knowl-
edge of the air-sea rhythms, extending
vertically to great heights in the
atmosphere, must be based mainly
on a study of the years from 1950
through 1967.
Oceanographic cruises in the equa-
torial belt have been few and far
between in space and time. The
EASTROPAC Program, a series of
internationally coordinated cruises in
the eastern tropical Pacific and trans-
equatorial cruises in the mid-Pacific,
sponsored by the U.S. National Ma-
rine Fisheries Service (NMFS), Hono-
lulu, has been the best oceanographic
effort to date to explore air-sea in-
teraction in the critical area where
the air-sea rhythms originate. Eess
sophisticated, widely scattered ob-
servations are available from com-
mercial ships. Those collected by the
NMFS in Honolulu from commercial
ships that ply the route from Hawaii
to Samoa have provided a time-series
of equatorial sea temperature at
165°W., together with the corre-
sponding sea-temperature series at
Canton Island. The two records agree
rather well as far as the long rhythms
are concerned.
Organized reporting of sea and
air temperatures from commercial
ships crossing the east and central
part of the Pacific tropical zone is in
good hands with the NMFS in La
Jolla, California; the monthly maps
issued by that institution are at
present the best source of informa-
tion on tropical air-sea rhythms.
The Status of Instrumentation ■ —
An important technical improvement
in the ocean data reported from
commercial ships will come soon.
Selected ships will be equipped with
Expendable Bathy-Thermographs
(XBT) to enable them to monitor the
varying heat storage in the ocean
down to the thermocline.
Anchored buoys can provide the
same information as XBT-equipped
commercial ships and will have the
advantage of delivery data for long
time-series at fixed locations. The
buoys that can be permanently fi-
nanced should preferably be placed
to fill the big gaps between fre-
quented shipping lanes. Also, their
locations should be selected where
ocean temperatures are likely to vary
significantly, for instance along the
equator.
Infrared radiometers on satellites
can be adjusted to record sea tem-
perature in cloud-free areas, but the
accuracy of such measurements can-
not quite compare with careful ship-
or buoy-based observations. The
great contributions of the satellites
to tropical studies are — presently
and in the future — the TV-mapping
of cloud distribution, the temperature
measurements of the top surface of
cloud, and, under favorable condi-
tions, the movement of individual
clouds and cloud clusters.
Fixed installations on tropical is-
lands will continue to be important
for research on ocean-atmosphere in-
teraction. Aerological soundings, in-
cluding upper wind measurements,
are best done from islands; moreover,
fundamental measurements like the
time variations of the topography of
ocean level can only be done with
a network of island-based tide
gauges. The latter job does not call
for very expensive equipment, and
the tide gauges can be serviced as
part-time work by trained islanders;
the aerological work, on the other
hand, calls for a technologically
skilled staff on permanent duty.
Replacements for Canton Island as
an aerological observatory would be
relatively expensive, but yet cheaper
than was Canton, if islands with
stable native population were selected
for observatory sites. The two British
islands of Tarawa (l°2l'N. 172°56'E.)
and Christmas (1°59'N. 157°29'W.)
would be ideal choices.
Mathematical Modeling — A crude
modeling of an asymptotically ap-
proached "steady state" of an equa-
torial ocean exposed to the stress of
constant easterly winds has been pro-
duced by Bryan, of the Geophysical
Fluid Dynamics Laboratory, NOAA.
A corresponding, quickly adjusting
atmospheric model of the equatorial
circulation, such as observed over the
Pacific, was described in 1969 by
Manabe, also of the Princeton NOAA
team.
Presumably, the ocean and atmos-
pheric models can soon be joined for
a simulation of the equatorial air-
sea rhythms. Even without mathe-
matical formulation, the rhythm can
be crudely visualized to operate as
follows:
The cooling phase of the rhythm
begins when the equatorial easterlies
of the eastern Pacific start increasing
and thereby start intensifying the
upwelling. This increases the tem-
perature deficit of the eastern end
of the oceanic equatorial belt com-
pared to its western end. The asso-
ciated feedback upon the atmosphere
shows up in an increased east-west
temperature contrast, which produces
an increment of kinetic energy in
the equatorial atmospheric circula-
tion. This, in turn, feeds back into
87
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
increasing upwelling and ocean-cool-
ing over an increasing area.
A corresponding chain reaction can
he visualized for the phase of the
rhythm characterized by decreasing
easterly winds, decreasing upwelling,
and increasing equatorial ocean
warming. Hence, a slow vacillation
between the two extreme phases of
equatorial atmospheric circulation,
rather than a stable steady-state
equatorial circulation, becomes the
most likely pattern.
Simulation experiments are pres-
ently being planned on a global basis,
encompassing both ocean and at-
mosphere; they will bring more pre-
cise reasoning into the explanation
of the equatorial air-sea rhythms
and, hopefully, into the interpretation
of their teleconnections outside the
tropics. Both the Princeton team, un-
der Smagorinsky, and the team at
the University of California, at Los
Angeles, under Mintz and Arakawa,
are progressing toward that goal.
Requirements for Scientific
Activity
Continued empirical study of the
tropical air-sea rhythms, in past and
in real-time records, should accom-
pany and support modeling efforts of
theoretical teams. The knowledge
gained on tropical air-sea rhythms
and their extratropical teleconnec-
tions so far rests on the study of
only a limited number of case his-
tories. Much more can be learned by
studying the whole sequence of years
1950-67, during which Canton Island
was available as an indicator of the
air-sea rhythms. These years include
the International Geophysical Year
period, which happened to exhibit
some extreme climatic anomalies and
also had better-than-normal global
data coverage.
Such investigations are relatively
cheap. The main expense goes into
the plotting and analysis of world
maps of monthly climatic anomalies
in several levels up to the tropopause.
Such a system of climatic anomaly
maps would be the empirical tool for
tracking the mechanism of the tele-
connections. Liaison with EASTRO-
PAC and other post-1950 Pacific
tropical oceanographic research would
become a natural outgrowth of the
"historical" study.
The 1970's is to be the era of the
International Decade of Ocean Ex-
ploration (IDOE) as well as that
of the Global Atmospheric Research
Program (GARP). The study of trop-
ical air-sea rhythms belongs within
the scope of both of these worldwide
research enterprises and, indeed, will
serve to tie the two together. The
ultimate goal of IDOE-plus-GARP
should be to model the atmosphere
and the world oceans into one com-
prehensive system suitable for elec-
tronic integration. That endeavor
should produce meaningful progress
toward climatic forecasting by the
end of the 1970's.
88
2. ATMOSPHERIC CIRCULATION
Modeling the Global Atmospheric Circulation
An understanding of the structure
and variability of the global atmos-
pheric circulation requires a knowl-
edge of:
1. The quality and quantity of
radiation coming from the sun.
2. The atmospheric constituents —
not only the massive ones, but
also such thermodynamically
active components as water va-
por, carbon dioxide, ozone, and
clouds as well as other partic-
ulates. Furthermore, one must
understand the process by
which these constituents react
with the circulations and their
radiative properties — i.e., ab-
sorption, transmission, scatter-
ing, and reflection.
3. The processes by which the
atmosphere interacts with its
lower boundary in the trans-
mission of momentum, heat,
and water substance over land
as well as sea surfaces. The
behavior of the atmosphere
cannot be considered independ-
ent of its lower boundary be-
yond a few days. In turn, the
lower boundary can react sig-
nificantly. Even the surface
layers of the oceans have im-
portant reaction times of less
than a week, while the deeper
ocean comes into play over
longer periods. Hence, the
evolution of the atmospheric
circulation over long periods
requires consideration of a dy-
namical system whose lower
boundary is below the earth's
surface.
4. The interactions of the large-
scale motions of the atmos-
phere with the variety of
smaller-scale motions normally
present. If these smaller scales
have energy sources of their
own, as is the case in the at-
mosphere, the nature of the
interactions will be consider-
ably complicated.
In principle, mathematical models
embodying precise statements of the
component physical elements and
their interactions provide the means
for numerically simulating the nat-
ural evolution of the large-scale at-
mosphere and its constituents. Suc-
cessful modeling would have potential
applications in a number of areas:
long-range forecasting; determination
of the large-scale, long-term disper-
sion of man-made pollutants; the
interaction of these pollutants in in-
advertently altering climate; the in-
fluence of intentionally tampering
with boundary conditions to arti-
ficially modify the climate equilib-
rium. No doubt there are a variety
of other applications of a simulation
capability to problems that may not
yet be evident.
Current Status
Efforts to model the large-scale
atmosphere and to simulate its be-
havior numerically began more than
twenty years ago. As additional re-
search groups and institutions in the
United States and elsewhere became
involved, steady advances in model
sophistication followed. These came
from refinements in numerical meth-
ods as well as from improved formu-
lations of the component processes.
Today's multi-level models account
for a variety of interacting influences
and processes: large-scale topographic
variations; thermal differences be-
tween continents and oceans; varia-
tions in roughness characteristics;
radiative transfer as a function of an
arbitrary distribution of radiatively
active constituents; large-scale phase
changes of water substance in the
precipitation process; interactions
with small-scale, convectively un-
stable motions; the thermal conse-
quences of variable water storage in
the soil; and the consequences of
snow-covered surfaces on the heat
balance. More recently, combined
models have taken into account the
mutual interaction of the atmosphere
and ocean, including the formation
and transport of sea-ice.
Although many of these elements
are rather crudely formulated as cogs
in the total model, it has been pos-
sible to simulate with increasing detail
the characteristics of the observed
climate — not only the global wind
system and temperature distribution
from the earth's surface to the mid-
stratosphere, but also the precipita-
tion regimes and their role in forming
the deserts and major river basins
of the world. Attention is beginning
to be given to the simulation of
climatic response to the annual radia-
tion cycle.
Detailed analyses of such simula-
tions in terms of the flow and trans-
formation of energy from the primary
solar source to the ultimate viscous
sink show encouragingly good agree-
ment with corresponding analyses of
observed atmospheric data. Such
models have also been applied to
observationally specified atmospheric
states in tests of transient predict-
ability. Even within the severe limita-
tions of the models, the data, and the
computational inadequacies, it has
been possible to simulate and verify
89
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
large-scale atmospheric evolutions of
the order of a week. These advances
give promise that, as known deficien-
cies are systematically removed, the
practical level of the large-scale pre-
dictability of the atmosphere can
converge on a theoretical determin-
istic limitation of several weeks.
Models have also been used in
some, more limited applications. For
example, an attempt was made to
simulate the long-term, large-scale
dispersion of inert tracing material,
such as radioactive tungsten, which
had been released at an instantaneous
source in the lower equatorial tropos-
phere. The results were surprisingly
good. Only limited attempts have
been made to apply extant models to
test the sensitivity of climate to small
external influences. The reason is
that one normally seeks to detect
departures from fairly delicately bal-
anced states. It is often beyond the
current level of capability to simulate
an abnormal response that is com-
parable in magnitude to the natural
variability noise level.
Observational Problems
The present large-scale data base
is essentially dictated by the extent
of the operational networks created
by the weather forecast services of
the world. The existing network is
hardly adequate to define the north-
ern-hemisphere extratropical atmos-
phere; it is completely inadequate in
the southern hemisphere and in the
equatorial tropics. For example, there
are only 50 radiosonde stations in
the southern hemisphere in contrast
to approximately 500 in the northern.
The main difficulties arise from the
large expanses of open ocean which,
by conventional methods, impede de-
termination of the large-scale com-
ponents of atmospheric structure
responsible for the major energy
transformations. This critical defi-
ciency in the global observational data
store makes it difficult to define the
variability of the atmosphere in
enough detail to discern systematic
theoretical deficiencies. Furthermore,
the data are inadequate for the spec-
ification of initial conditions in the
calculation of long-range forecasts.
Recent dramatic advances in in-
frared spectroscopy from satellites
promise significant strides in defining
the state of the extratropical atmo-
sphere virtually independent of loca-
tion. (See Figure IV-6) However, the
motions of the equatorial tropical at-
mosphere lack strong rotational cou-
pling, making the observational prob-
lem there more acute. Independent
wind determinations may be needed
as well as the information supplied by
a Nimbus 3 (SIRS sensor) type satel-
lite. It is not yet known to what ex-
tent balloon-borne instrumentation or
measurements from ocean buoys will
be needed to augment satellite obser-
vations, especially in the lower tropos-
phere. This will depend on just
how strongly the variable character-
istics of the atmosphere are coupled.
A more precise knowledge would per-
mit relaxing observational require-
ments for an adequate definition of
its structure.
Figure IV-6 — SIRS SOUNDING
T
5
Id
(T
</>
to
UJ
<r
a.
100
1000
35
I-
I
o
UJ
I
200
300
250
TEMPERATURE (#K)
(Illustration Courtesy ot the American Meteorological Society )
This figure shows the broad similarities between simultaneous temperature sound-
ings obtained by radiosonde equipment and satellite-borne SIRS (Satellite Infrared
Spectrometer) and IRIS (Infrared Interferometer Spectrometer) systems. The latter
systems, however, are able to provide far broader and more continuous coverage
than conventional equipment. Further work is in progress to overcome the difficul-
ties of the present instruments in predominantly overcast areas.
90
ATMOSPHERIC \TION
There is some controversy as to
the inherent deterministic limitations
of the predictability of the atmos-
phere— say, for scales corresponding
to individual extratropical cyclones.
The span of controversy ranges from
about one to several weeks. More-
over, it is not known at all whether
longer-term characteristics of atmos-
pheric variability are determinate.
For example, is it inherently possible
to distinguish the mean conditions
over eastern United States from one
January to another in some deter-
ministic sense? In the equatorial
tropics there is very little insight as
to the spectrum of predictability.
Needs for Future Improvements
Broadly, there are three areas that
require intensive upgrading, the first
two of which are essentially tech-
nological:
Technological Requirements — The
need for establishment of an adequate
global observing system has already
been discussed. In addition, com-
puters two orders of magnitude faster
than those currently available are
needed to permit the positive reduc-
tion of mathematical errors incurred
by inadequate computational resolu-
tion. Faster computers will also per-
mit more exhaustive tests of model
performance over a much larger
range of parameter-space to assess
the sensitivity of simulations to
parameterizations of physical process
elements of the model. Faster com-
puters will also provide an ability
to undertake the broad range of ap-
plications implied by a more sophisti-
cated modeling capability.
Scientific Requirements — The sci-
entific requirements stem from the
necessity of refining the formulation
of process elements in the models.
To cite a few: boundary-layer inter-
actions — to determine the depend-
ence of the heat, momentum, and
water-vapor exchange within the
lower kilometer of the atmosphere
as a function of the large-scale struc-
tural characteristics; internal turbu-
lence — to determine the structure
and mechanisms responsible for in-
termittent turbulence in the "free"
atmosphere, which is apparently re-
sponsible for the removal of signifi-
cant amounts of energy from the
large scale and may also play a role
in the diffusion of heat, momentum,
and water vapor; and convection —
to determine how cumulus overturn-
ing gives rise to the deep vertical
transport of heat, water vapor, and,
possibly, momentum.
We still do not know the con-
sequences of particulates, man-made
or natural, either directly on the
radiative balance or ultimately on
the dynamics.
In the tropics, we have yet to com-
pletely understand the instability
mechanisms responsible for the for-
mation of weak disturbances or the
nature of an apparent second level
of instability which transforms some
of these disturbances into intense
vortices, manifested as hurricanes
and typhoons. Without an under-
standing of the intricacies of the
tropics, it is impossible to deal com-
prehensively or coherently with the
global circulation, particularly with
the interactions of the circulation of
one atmosphere with that of the
other.
Most of these critical scientific
areas of uncertainty require intensive
phenomenological or regional obser-
vational studies. These will provide
the basic data as foundations for a
better theoretical understanding.
Any one of the general scientific
and technological categories listed
above may at any one time provide
the weakest link in the complex
required to advance a modeling and
simulation capability. Obviously,
then, they must be upgraded at com-
patible rates.
Prospects
A comprehensive look at the status,
needs, and implications of an under-
standing and simulation capability of
the global circulation is embodied in
the Global Atmospheric Research
Program (GARP), which was estab-
lished several years ago as an inter-
national venture under the joint
auspices of the World Meteorological
Organization and the International
Council of Scientific Unions. In the
United States, GARP is overseen by
a National Academy of Sciences
committee that has produced a plan-
ning document for U.S. national par-
ticipation. Almost all the problem
areas discussed above have come to
the attention of the U.S. Committee
for GARP. The international time-
scale for major field experiments ex-
tends into the late 1970's. Concomi-
tantly, national and international
research programs to support and
derive results from the field programs
will be established. The time-scales
governing GARP planning imply that
one can expect the necessary elements
to be systematically undertaken over
about a ten-year period. The first
GARP tropical experiment will take
place in 1974 in the eastern equatorial
Atlantic and the first GARP global
data-gathering experiment is sched-
uled for 1976 or later. GARP is the
research part of the World Weather
Program (WWP). The other part of
the WWP is the World Weather
Watch (WWW), whose objective is
to bring the global atmosphere under
surveillance and provide for the
rapid collection and exchange of
weather data as well as the dissemi-
nation of weather products from cen-
tralized processing centers. GARP
will rely heavily on data obtained
from the WWW. (See Figure IV-7)
91
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
FIGURE IV-7 — AVAILABILITY OF UPPER AIR DATA
*
The map shows the current and planned global radiosonde network. The current
network is adequate only over Europe, central Asia, and the United States. The
planned additions will add greatly to our knowledge of the southern hemisphere; they
are part of the first phase of the World Weather Watch.
92
3. WEATHER FORECASTING
Short-, Medium-, and Long-Term Forecasting
The effects of weather on human
activities and the importance of ac-
curate weather predictions and timely
weather warnings for human safety
and comfort hardly need stating. The
farmer, the seafarer, the aviator, the
man on the street all share a com-
mon concern for the weather. Hurri-
canes, tornadoes, floods, heavy snows,
and other severe weather phenomena
take a heavy toll of lives and cause
billions of dollars loss in damage and
disruption each year. The cost would
be even greater were it not for
weather warnings and forecasts.
As the science of weather predic-
tion grows, it touches an ever wider
range of human problems. Today
there is much concern about air pol-
lution and the possible effects of pol-
lutants on weather and climate. The
mathematical models used in numeri-
cal weather prediction provide the
best known means of determining
how pollutants are spread over large
distances and how they might affect
weather patterns. Furthermore, math-
ematical modeling has reached the
stage where interactions of the at-
mosphere with the ocean can be
taken into account. This development
opens up the possibility of predicting
changes in the physical state of the
upper layers of the ocean, which
might prove useful to the fishing in-
dustry and other marine activities.
Although of great economic value,
present-day forecasts fall well short
of perfection. Even modest improve-
ments in accuracy would result in
substantial additional benefits. With
the new tools now available, espe-
cially the meteorological satellite, op-
portunities exist for increasing the
accuracy of forecasts at all ranges —
short, medium, and long.
The Nature of Weather Prediction
It is customary, and for some pur-
poses useful, to divide the subject of
weather prediction into three cate-
gories: short, medium, and long
term. These categories are generally
understood to refer to time ranges of
0-24 hours, 1-5 days, and beyond
5 days (e.g., monthly and seasonal
forecasts), respectively. While it is
often convenient to discuss the fore-
cast problem under these headings,
it is important to realize that they
do not necessarily represent logical
divisions of the subject in terms of
methodology employed, concepts in-
volved, or phenomena treated.
Weather prediction, as presently
practiced, is actually a highly com-
plex subject. It deals with such
diverse phenomena as thunderstorms,
tornadoes, hurricanes, and cyclonic
storms, and with a wide variety of
weather elements — wind, tempera-
ture, and precipitation, to name a few
of the more important. Moreover, it
involves the use of an assortment of
techniques, some based on human
judgment, others founded on physical
law and numerical computation.
Weather forecasting is still a mixture
of art and science, but a mixture in
which the scientific ingredient is be-
coming increasingly dominant as fun-
damental understanding of the at-
mosphere grows and more and more
application is found for numerical
methods.
In the following sections we will
review the principal elements in-
volved in prediction at different
ranges, dividing the subject according
to the pertinent phenomena. Figure
IV-8 shows the geographical range,
both latitudinally and in height, of
data needed for forecasting. To aid
in the discussion, it is desirable first
to summarize briefly the methods
employed in weather prediction.
Prediction Methods
Numerical Weather Prediction —
This is the term applied to forecast
methods in which high-speed digital
computers are used to solve the
physical equations governing atmos-
pheric motions. In order to compute
the future state of the atmosphere
accurately, the initial or present state
must be specified by observation.
Numerical methods are most success-
fully applied in predicting the be-
havior of the synoptic-scale disturb-
ances (cyclones, anticyclones, jet
streams) of middle and high latitudes.
Extrapolation — In this method,
successive positions of the feature
being forecast, for instance a low-
pressure center, are mapped, and the
future position is estimated by con-
tinuing past displacements or trends.
Since the advent of numerical weather
prediction, this method has fallen into
disuse in predicting motions of syn-
optic systems, but it is still useful in
other connections, for example, in
predicting movements of individual
thunderstorms seen on a radarscope.
Steering — In the steering method,
a smaller-scale weather system or
feature is assumed to move with the
direction and speed of a larger-scale
current in which it is embedded.
Thus, a hurricane may be displaced
according to the broad-scale trade-
wind current in its vicinity. The ac-
curacy of the method depends on how
well the basic steering assumption
is satisfied and how accurately the
steering current is known or pre-
dicted.
93
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
Figure IV-8 — DATA REQUIRED FOR FORECASTS
LATITUDE
0 20
The diagram gives an indication of the data necessary for forecasts in the middle
latitudes for varying lengths of the forecast period. It is important to note that both
atmospheric and oceanographic data are needed for all forecast periods.
ena selected on the basis of their
practical importance: severe local
storms (thunderstorms, hailstorms,
and tornadoes); hurricanes; and syn-
optic disturbances (cyclones, anticy-
clones, and fronts and their asso-
ciated upper-level troughs, ridges,
and jet streams).
Severe Local Storms — These
storms develop with extreme rapidity
and seldom have lifetimes of more
than a few hours. On the basis of
the large-scale temperature, moisture,
and wind fields, and their expected
changes, it is possible to delineate
areas in which severe storms are
likely to occur 6 to 12 hours in ad-
vance, or sometimes even longer. But
there is at present no way of predict-
ing when and where an individual
storm will develop. Once a storm
has been detected, extrapolation and
steering methods can be used to
predict its motion with fair accuracy,
but in view of the short lifetime of
the typical storm, the forecast rarely
holds for more than a few hours.
Statistical Forecasting — Though
statistical methods have wide appli-
cation in forecasting, the term, as
applied here, refers to any of a num-
ber of techniques in which past data
samples are employed to derive sta-
tistical relationships between the
variable being forecast and the same
or other meteorological variables at
an earlier time. The statistical method
is particularly valuable in forecasting
local phenomena that are too complex
or too poorly understood to be
treated by numerical or physical
methods but that experience has
shown to be related to identifiable,
antecedent causes.
The Analogue Method — The aim
of this method is to find a previous
weather situation which resembles
the current situation and to use the
outcome of the earlier case to deter-
mine the present forecast. The
method has the advantage of sim-
plicity, but its usefulness is extremely
limited since sufficiently close ana-
logues are difficult to find, even when
long weather records are available.
Mixed Methods — Combinations
of the foregoing methods are quite
common. Thus, surface temperature
is customarily forecast by a combina-
tion of numerical and statistical tech-
niques in order to obtain better
predictions than would be obtained
from use of the numerical method
alone.
Short-Range Prediction
The problems encountered, meth-
ods employed, and the time period
for which accurate predictions can
be made differ according to the phe-
nomenon or scale of motion being
forecast. It is therefore convenient
to discuss the subject on the basis
of different types of weather systems
involved. To keep the subject within
reasonable limits, the discussion will
be limited to the following phenom-
Weather radar is the most valuable
tool in severe-storm detection, and
it is only since the introduction of
radar that adequate monitoring of
severe storms has been possible.
Geostationary satellites also have
great potential usefulness in identify-
ing and tracking these systems. Until
there is full radar coverage of the
United States and permanent surveil-
lance by geostationary satellite with
both visual and infrared sensing ca-
pability, short-range prediction of
severe storms will not have reached
the limits of accuracy allowed by the
present state of the art.
Ultimately, one may hope that the
methods of numerical weather pre-
diction used so successfully with
larger-scale storms will be applied to
thunderstorms and other small-scale
phenomena. But there seems no clear
way of achieving this hope in the
foreseeable future. To forecast these
phenomena by numerical methods re-
quires observations of the basic me-
teorological variables — wind, tem-
94
WEATHER TORLCASTING
perature, and moisture — at spatial
intervals of less than a kilometer and
nearly continuously in time (cf., pre-
sent spacing of about 400 km. and
time intervals of 12 hours). Eco-
nomically, this is a prohibitive re-
quirement, quite apart from its prac-
tical feasibility in terms of the
instrumentation and observing sys-
tems currently envisaged.
Despite the present hopelessness
of straightforward applications of
physical-numerical methods to the
prediction of small-scale phenomena,
there is no doubt that opportuni-
ties exist for improved forecasting
through properly directed research
efforts. New developments in instru-
mentation and measuring systems —
doppler and acoustic radars and the
geostationary satellites, to mention
the most promising — utilized in con-
junction with special observing pro-
grams planned for the future, offer
great opportunities for advancing un-
derstanding of severe storms. From
this understanding, improved tech-
niques are bound to emerge. For in-
stance, it has been found that, unlike
the typical thunderstorm, very large
thunderstorms tend to move to the
right and slower than the steering
current. A better physical under-
standing of the cause of this behavior
would undoubtedly lead to superior
forecast techniques.
Hurricanes — Hurricane prediction
has improved steadily during the past
decade or two. The improvement has
been brought about by the use of
aerial reconnaissance, radar, and,
more recently, meteorological satel-
lites to detect and track the hurricanes
and by the development of better
techniques for predicting their move-
ment. Skill is still largely lacking in
forecasting their development, but
fortunately they form sufficiently
slowly and usually far enough away
from land areas that the development
problem is seldom critical.
In the past, extrapolation and steer-
ing methods have been the mainstays
in predicting hurricane movement.
Currently, the most accurate method
is a statistical one that uses past
weather records to derive regression
equations relating future movement
to previous movement and to various
measures of the large-scale atmos-
pheric structure in the region sur-
rounding the hurricane. With this
method, hurricane positions can be
predicted 24 hours in advance with
an average error of about 100 nauti-
cal miles. While this figure leaves
considerable room for improvement,
there can be no doubt about the
enormous value of current forecasts
in terms of lives saved and property
damage reduced.
Further refinement of the statistical
method and better observations of
the broad-scale features of the hurri-
cane environment could lead to some
improvement in hurricane prediction,
but it seems likely that the statistical
method has already approached its
limits of accuracy. Development of
numerical prediction methods would
seem to hold the key to further prog-
ress in this area. Methods of numeri-
cal prediction have already been tried
which forecast the large-scale steering
flow in the vicinity of hurricanes and
thereby allow better use of the steer-
ing principle. These methods have
met with some degree of success,
yielding errors comparable to, or
slightly larger than, the statistical
method.
More significant and promising for
the future has been the development
in recent years of theoretical models
which, starting from assumed initial
conditions, are able to simulate many
important features of hurricanes.
These models have reached the stage
where they could be tested routinely
in the atmosphere if the proper initial
data — i.e., observations of wind,
temperature, and humidity at suffi-
ciently close intervals to resolve the
atmospheric structure in and near the
hurricane — were available. The in-
terval required is 100 kilometers or
less, well beyond present observa-
tional capability. However, it is con-
ceivable that geostationary satellites
with visual and infrared sensoi
eluding sounders, could go a long
way toward providing the type of
information needed for carrying out
physical-numerical prediction of hur-
ricane formation, movement, and in-
tensity.
Despite these promising theoretical
and observational developments, it
would be premature to enter on a
crash program of hurricane predic-
tion. Emphasis now must be put on
improving the physical basis of hur-
ricane models and on developing the
full potential of the geostationary
satellite as an observing platform.
Tropical field experiments planned as
part of the Global Atmospheric Re-
search Program (GARP) will assist
theoretical studies of hurricanes by
providing data suitable for investi-
gating the nature of the interaction
of mesoscale convective phenomena
with the larger-scale flow patterns of
the tropics.
Synoptic Systems — During the
past decade or two, thanks to the in-
troduction of high-speed computers
and the development of numerical
weather prediction, remarkable prog-
ress has been made in predicting the
genesis and movement of high and
low pressure systems and tropos-
pheric circulation features in general.
Prognostic weather maps prepared by
computer now surpass the efforts of
even the most skilled and experienced
forecasters.
Despite these successes, short-range
forecasts of specific weather elements
often leave much to be desired. In
part, the shortcomings are due to
small-scale phenomena which, as ex-
plained earlier, are not predictable,
except in a statistical sense, more than
a few hours in advance. But, in con-
siderable measure, they can also be
attributed to deficiencies or limita-
tions in the numerical prediction
models. The models are most suc-
cessful in predicting pressure and
wind fields; they are less successful
in predicting cloud and precipitation
amounts and patterns and in answer-
95
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
ing such critical problems as whether
precipitation will be in the form of
rain or snow. These problems, in-
volving interactions of wind, tem-
perature, and moisture fields, are of a
different order of difficulty. Short-
range predictions also suffer some-
what from data deficiencies, particu-
larly in oceanic and adjoining regions.
Satellite observations have, however,
alleviated the data deficiencies to a
considerable degree in recent years.
There are several avenues for ad-
vancing the science of short-range
prediction of synoptic-scale phenom-
ena; all of them are being actively
pursued and deserve encouragement.
First, fine-grid scale models are being
developed which accept data at grid
intervals of half or less the current
standard mesh length of about 400
kilometers. Use of a finer grid per-
mits better resolution and more accu-
rate depiction of the synoptic patterns
and improves the accuracy of the
computational procedures. Unfortu-
nately, the presently available obser-
vations are not ideally suited for
fine-grid computation. Though a net-
work of surface observations exists
which makes it possible to represent
surface weather features more pre-
cisely than is presently done in nu-
merical prediction, no corresponding
closely spaced upper air observations
are available. High-resolution, scan-
ning radiometric sounders aboard
satellites offer a promising means of
overcoming this gap, and every effort
should be made to speed their devel-
opment and application. Data from
more advanced satellites can also be
expected to improve further the qual-
ity of ocean analysis, and thereby
contribute to better short-range fore-
casts over ocean areas and adjacent
coastal regions.
Another important avenue for ad-
vancing short-range prediction is
through continued efforts at improv-
ing the physical basis of the predic-
tion models. Such efforts can be
carried out in part bv theoretical
means, using presently available
knowledge of the physical processes.
But they will also almost certainly
require the acquisition of special data
sets of the sort planned under GARP
and other large observational pro-
grams. Better modeling of the physi-
cal processes will not only widen the
scope of the phenomena that can be
forecast successfully by objective
means but will result in greater ac-
curacy of the forecast as a whole.
A final important new direction in
short-range prediction is in modeling
of the near surface layer. This is the
layer that affects man most directly.
Accurate predictions of its structure
will contribute to successful predic-
tions of the dispersal of pollutants in
the atmosphere, and of fog and other
visibility- and ceiling-reducing fac-
tors that hamper aircraft operations.
Modeling of this layer is a difficult
undertaking, since its characteristics
and behavior are controlled in large
measure by turbulent processes. Both
theoretical work and field observa-
tional programs will be required to
advance this effort. We are still a
long way from being able to make
surface-layer prediction a part of the
routine prognosis.
Medium-Range Prediction
During the past dozen years, the
greatest gains in forecast skill have
probably occurred at medium range
(1-5 days). These gains are the direct
outcome of the development and ap-
plication of numerical prediction
models capable of forecasting the for-
mation and movement of synoptic-
scale weather systems. The method
differs in no way from that described
in connection with short-range pre-
diction; it is simply extended for a
longer period.
Surface weather predictions are
now quite satisfactory for periods of
about 48 hours. Upper-level prog-
noses show some degree of skill for
periods as long as three to five days.
Again, pressure and wind patterns
are better forecast than such elements
as precipitation. At medium ranges
it is still possible to infer likely areas
of convective activity — thunder-
storms and the like — but prediction
of individual small-scale disturbances
is completely beyond the realm of
possibility.
Numerical experiments conducted
as part of GARP suggest that it is
possible, in principle, to forecast day-
to-day weather changes for periods
as long as two to three weeks in ad-
vance — though some critics feel this
is an excessive figure in terms of
what the public would judge to be
successful forecasting. In any event,
there is good reason to believe that
useful forecasts can be made by nu-
merical methods for periods well in
excess of the present three-to-five day
limit.
The main obstacles in the way of
increasing the time range of forecasts
(and thereby also their accuracy, even
at shorter ranges) are the lack of an
adequate observational network on a
worldwide basis and deficiencies in
the physical formulation of the pre-
diction models. A principal aim of
GARP is to overcome these observa-
tional and physical shortcomings.
A number of areas or industries
have been identified in which more
accurate predictions in the five- to
twenty-day range would result in
great economic benefit. Among these
are agriculture, transportation, public
utilities, and the construction and
fishing industries.
Long-Range Prediction
Long-range prediction is a contro-
versial subject. Its proponents make
a variety of claims, ranging from the
ability to forecast a given day's
weather weeks or months in advance
to the ability to forecast, with some
small degree of skill, departures of
temperature or precipitation from
their monthly or seasonal means.
Skeptics contend that the whole busi-
ness is a waste of time, either that we
do not know how to make long-range
predictions or that long-range pre-
96
WEATHER
diction is an impossibility. Where
does the truth lie?
First we might ask: Are there valid
grounds for attempting long-range
prediction? Here the answer is defi-
nitely "yes." If weather changes were
due exclusively to migratory synoptic-
or smaller-scale weather systems, it
is known from the GARP experiments
cited previously that prediction would
not be possible beyond two or three
weeks. But it has long been recog-
nized that there are larger-scale pat-
terns in the atmosphere which tend to
persist or recur over periods of weeks,
months, or seasons. Drought episodes
and prolonged spells of warm or cold
weather may be cited as examples of
such patterns. They are associated
with abnormal features of the circu-
lation— unusual displacements of the
jet stream, the semi-permanent high
and low pressure centers, and so
forth.
Theories of Causation — The cause
of long-period weather changes is a
debatable subject. Many investiga-
tors have sought to connect them to
extraterrestrial events — to variations
of solar radiation, in particular — but
the evidence in favor of an extrater-
restrial origin is not impressive. Other
investigators have suggested that they
are caused by complex feedback
mechanisms within the atmosphere.
This hypothesis cannot be discounted.
In laboratory experiments with rotat-
ing fluids, it has been found possible
to generate long-period (on the time-
scale of the model) circulation fluctua-
tions even when external conditions
are kept rigidly constant.
A final theory, which has steadily
gained support, attributes long-period
weather variations to interactions of
the atmosphere with surface features.
Anomalies of sea-surface temperature
and of snow cover are examples of
conditions that are believed capable
of producing and perpetuating abnor-
mal weather situations.
Forecasting Metlwds — Though
some physical reasoning may enter
into the formulation of a long-range
forecast, the methods currently in use
do not have a physical basis. The
numerical methods applied at shorter
ranges are not, as presently formu-
lated, appropriate to long-range pre-
diction.
Thus, main reliance is put on ex-
trapolation, statistical, and analogue
methods of forecasting, and human
judgment plays a heavy role. The
results obtained from these methods
show at best only slight skill, and
there seems little or no hope of sig-
nificant improvement through their
continued use and development. How-
ever, in view of the great economic
importance of long-range prediction
and the growing evidence that a
meaningful physical understanding
of long-period atmospheric variations
can be achieved, it is essential that
efforts to derive more suitable quanti-
tative methods of prediction be con-
tinued and strengthened.
Needed Scientific Activity — Ac-
tivities of two types deserve particu-
lar encouragement in this respect.
First are programs to acquire the kind
of global data needed for establishing
the physical basis of long-range pre-
diction. Such programs will have to
endure for a long time and will not
only have to measure the usual me-
teorological variables employed in
numerical prediction but will have to
measure additional parameters such as
sea-surface temperature, snow cover,
and the like. It is apparent that ob-
servations from satellites will be the
key element in a global monitoring
effort.
A second type of activity that
merits vigorous support is experi-
mental work in numerical modeling
of the general circulation, of the sort
now practiced by a number of groups
in the United States. From such ex-
periments, it may well be possible to
discover the underlying causes of
long-term weather and climatic anom-
alies. In fact, the modeling experi-
ments are essential to the observa-
tional effort, for without them we can
never be sure, until perhaps it is too
late, that the proper variables are
being measured.
Long-Range Weather Forecasting
Scientists who work in long-range
weather forecasting encounter great
difficulties, not only in the intricacies
of their chosen field but also in get-
ting across to other scientists and the
lay public the essential nature of
their problem and the reasons for
their painfully slow progress in the
modern-day milieu of satellites, com-
puters, and atomic reactors. When
solar eclipses can be predicted to frac-
tions of a second and the position of
a satellite pinpointed millions of miles
out in space, it is not readily under-
standable why reliable weather pre-
dictions cannot be made for a week,
month, season, or even a year in
advance. Indeed, eminent scientists
from disciplines other than meteorol-
ogy, underestimating the complexity
of the long-range problem, have tried
to solve it only to come away with a
feeling of humility in the face of
what the late von Neumann used to
call "the second most difficult prob-
lem in the world" (human behavior
presumably being the first).
And yet, the potential economic
value of reliable long-range forecasts
probably exceeds that for short-range
(daily) forecasts. Many groups need
as much as a month or a season or
more lead-time to adjust their plans.
These include such diverse types as
manufacturers (e.g., summer suits,
97
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
raincoats, farm implements), fuel and
power companies, agriculturalists,
construction companies, and com-
modity market men, to say nothing
of vacationers. Aside from this, long-
range forecasting, by setting the cli-
matic background peculiar to a given
month or season, is of distinct value
to the short-range forecaster. For ex-
ample, it can alert him to the likeli-
hood of certain types of severe
storms, including hurricanes, intense
extratropical cyclones, and even broad
areas most frequently vulnerable to
tornadoes.
Most of the needs of these groups
for long-range forecasts cannot pres-
ently be met, however, because of the
low skill level of predictions or the
inability to predict anomalous weather
at ranges beyond a month or season.
Why is the problem so intractable?
The General Problem
In the first place, long-range fore-
casting requires routine observations
of natural phenomena over vast areas
— and by vast we mean at least
hemisphere-wide coverage in three
dimensions. More probably, the en-
tire world's atmosphere, its oceans
and its continents, must be surveyed
because of large-scale interactions
within a fluid that has no lateral
boundaries but surrounds the entire
earth. In contrast to the physicist,
the meteorologist has no adequate
laboratory in which to perform con-
trolled experiments on this scale, al-
though some recent work with elec-
tronic computers holds out hope for
useful simulation.
Inadequate Observational Net-
works — When the immense scale of
the atmosphere is realized, it becomes
clear that the present network of
meteorological and oceanographic ob-
servations is woefully inadequate.
Even in temperate latitudes of the
northern hemisphere, relatively well
covered by surface and upper-air re-
ports, there are "blind" areas of a
size greater than that of the United
States. The tropics are only sparsely
covered by reports, and the data cov-
erage in the southern hemisphere is
poorer still.
In the southern hemisphere, a moat
thousands of miles in diameter sepa-
rates the data-rich antarctic continent
from the temperate latitudes, making
it virtually impossible to get a coor-
dinated picture of what is occurring
now, let alone what may occur in the
future. The "secrets of long-range
forecasting locked in Antarctica" — a
cliche often found in press articles —
are indeed securely locked. Of course,
cloud and radiation observations from
satellites are assisting to an ever in-
creasing degree, but better methods
of determining the atmosphere's pres-
sure, wind, and temperature distribu-
tion from satellite and other types of
observations are urgently needed.
Inadequate Understanding — Even
if every cubic mile of the atmosphere
up to a height of 20 kilometers were
continuously surveyed, however (and
there are 2,500 million such volumes),
reliable long-range forecasts would
still not be realizable. Regardless of
their frequency and density, observa-
tions are not forecasts; they merely
provide "input data" for extended
forecasting. Meteorologists have yet
to develop a sufficient understanding
of the physics of the atmosphere and
the ocean to use these input data
effectively in long-range forecasting,
although this understanding is un-
likely to come about in the absence
of such data.
The Present Situation
The Data Base — Today the data
and facilities for making long-range
forecasts, inadequate as they may be,
are far better than ever. In addition
to about 25,000 surface weather re-
ports (22,000 over land and 3,000
over sea) available each day at a
center like Washington, there are 900
balloon observations of wind direc-
tion and speed, and 1,500 radiosonde
observations of upper air pressure,
temperature, and humidity and, fre-
quently, wind. In the same 24-hour
period about 1,300 aircraft reports,
dozens of indirect soundings of up-
per air temperatures made by the
Nimbus-SIRS satellite system, and
hundreds of satellite cloud photo-
graphs are received.
While these figures are impressive
they are inadequate, especially be-
cause they represent a most tineven
geographical array of observations
and neglect proper surveillance of the
ocean. The vast blind areas are, un-
fortunately, located in important wind
and weather system-generating areas,
like the northern Pacific Ocean, the
tropics, and parts of the southern
hemisphere. These systems, once
generated, soon influence weather in
distant areas around the world, their
complex effects often traveling faster
than the storms themselves. Hence,
if an area is especially storm-prone
during a particular winter, the storms
will persistently influence other areas
thousands of miles distant, sometimes
leading to floods or droughts. Obvi-
ously, if the wind and weather char-
acteristics in the primary generating
area are imperfectly observed one
cannot hope to predict the distant
responses.
As pointed out earlier, data alone,
regardless of how extensive in space
and how frequent in time, are not
sufficient to insure reliable long-range
forecasts. It does appear, however,
that more data of special kind and
accuracy are required if a successful
solution is to be obtained. The kinds
of data required and a rough estimate
of the density will be discussed later.
State of the Art — Forecasts can be
made for future days by using elabo-
rate numerico-dynamical methods and
high-speed computers. In these meth-
ods, one predicts various meteoro-
logical elements at many levels for
successive time-steps. The approach
always begins with the initial condi-
tions observed at many levels at a
certain time over a large area like the
northern hemisphere and forecasts
98
I
for time-steps of about 15 minutes.
Each iteration starts from the last
prediction, and the forecast is carried
forward for many days.
Numerical predictions of this kind
form the basis for the extended (5-
day) forecasts made by the National
Weather Service, an additional com-
ponent being supplied by the experi-
ence of the forecaster. How accurate
are they?
The skill of the final pressure-
pattern predictions made by the pres-
ent "man-machine mix" from two to
six days in advance is shown in
Figure IV-9 by the curve marked
"Present." Without going into de-
tails, 1.00 on the vertical scale implies
perfect forecasts, and 0 indicates fore-
casts that are no better than maps
randomly selected from the same
month of past years. As can be seen
in Figure IV-9, extended forecasts de-
teriorate rapidly from day to day; by
the sixth day, one might as well use
the initial day's map as a forecast
("persistence"). Even at the fourth
day, the skill is low enough to be of
marginal economic value. Assuming,
however, that the present accuracy of
forecasts for the fourth day are eco-
nomically valuable, we might ask
Figure IV-9 — FORECASTING SKILL
1.00
BASED ON 156 CASES
The graph shows the accuracy — and limitations — of National Weather Service
forecasts of the pressure pattern for North America for the period March 1968 to
February 1969.
how good the two- to six-day predic-
tions would have to be to give us
accuracy equal to the four-day figure
at two weeks, or 14 days in advance.
These computed values are shown in
the upper curve marked "Future."
Thus, we see that a six-day forecast
will have to be about as good as a
two-day forecast is now. A six-day
forecast will have to be about 25
times better than at present (ratio of
the squares of the six-day correlations
for "Present" and "Future"), a four-
day forecast about 10 times better.
Prospects — These are tremendous
strides that will have to be made,
especially if one considers the frus-
tratingly slow rate of progress in
improving short-range weather fore-
casts over the past twenty years. The
situation suggests that some major
breakthrough in understanding, and
in the density and quality of observa-
tions, must come about before de-
tailed predictions in time and space
out to two weeks or more will be
realized. There is controversy in the
meteorological community as to
whether forecasts of this type will
ever be possible.
Yet the potential for economically
valuable long-range predictions is not
as bleak as might be gathered from
this discussion. While the forecast
for a given day well in advance may
be greatly in error using the above
method, the general weather charac-
teristics of a period — say, the aver-
age of computerized forecasts for the
second or third week in advance —
may turn out to contain economically
valuable information. There is still
no evidence this is so, but the hope
exists that better and more observa-
tions combined with more knowledge
of atmospheric modeling will result
in this advance. Numerical modeling
may make a major spurt forward be-
cause of the development of a first
model aimed at coupling air and sea.
What Needs To Be Done
In order to bring about this prog-
ress and raise the level of the "Pres-
99
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
ent" curve in Figure IV-9, a vast
World Weather Watch (WWW) pro-
gram to acquire an adequate network
of observations has been set in mo-
tion by the WMO (World Meteoro-
logical Organization) and a compan-
ion research arm, GARP (Global
Atmospheric Research Program), un-
der IC5U (International Council of
Scientific Unions) and WMO. The
aims, rationale, and scope of these
undertakings have been well docu-
mented in many reports and will not
be reiterated here; suffice to say that
a satisfactory solution of long-range
forecasting problems is not likely to
come about without them.
Statistical Aggregation — Neverthe-
less, the future of long-range weather
forecasting does not and should not
depend solely on the possibilities in-
herent in the iterative approach de-
scribed earlier. Virtually every group
of meteorologists that has attacked
this problem over the past century
has done so by working not with
short time-step iterations but, rather,
by studying statistical ensembles and
the evolution of average wind and
weather systems — e.g., from month
to month and season to season. The
long-range forecasting services of the
Soviet Union, England, Japan, and the
United States operate with statistical
aggregates as well as physical meth-
ods. In the statistical approach, it is
taken for granted that the average
prevailing wind and weather patterns
for one month, together with the
associated abnormalities of sea tem-
peratures and land surfaces (e.g.,
covered or free of snow), largely de-
termine how the general weather pat-
terns are going to develop during the
following month under the influence
of the solar radiation appropriate to
time of year. A small effort in nu-
merical modeling using this philoso-
phy has begun.
How good are long-range predic-
tions by conventional non-iterative
methods? This is a question of scien-
tific as well as practical importance,
because any positive skill over and
above climatological probability im-
plies knowledge that ought to funnel
into further research and thereby lead
to more reliable prediction. The pres-
ent skill at forecasting departures
from normal of average temperature
at 100 cities over the United States
for 5-day, 30-day, and experimental
seasonal forecasts may be roughly
given as 75, 61, and 58 percent, re-
spectively, if chance is defined as 50
percent. Similarly, for precipitation,
5-day, 30-day, and seasonal forecasts
average roughly 5<5, 52, and 51 per-
cent, respectively. While these skills
are far from perfect they do indicate,
particularly for temperature, that the
methods contain some knowledge of
long-term atmospheric behavior. The
5- and 30-day forecasts that are re-
leased to the public appear to be of
definite economic value, judging from
hundreds of comments by users and
also from their reaction when the
forecasts are not received on time.
Despite the work and performance
of many groups around the world
along these practical lines and the
fact that their forecasts show some
small but definite skill in long-range
prediction (contrasted with the utter
failure, up to now, of dynamical
iterative models at periods up to
a month), the statistical-physical-
synoptic (synoptic here meaning an
over-all view with the help of maps)
approach has been relatively neg-
lected by meteorologists in the United
States.
The Role of Oceanography —
Oceanographers may see the long-
range problem more clearly than me-
teorologists as one in which statistical
aggregates play an important part —
both in forecasting general thermal
conditions in the sea and in forecast-
ing its long-period interaction with
the atmosphere. Perhaps this is be-
cause large-scale changes in the sea
take place much more slowly (about
ten times more slowly) than in the
atmosphere and the reasons can
therefore provide a sort of memory
bank for the atmosphere.
In the past decade, research has
shown that the thermal state of the
oceans, especially the temperatures in
the upper few hundred meters, varies
considerably from month to month
and year to year, and that these vari-
ations are both cause and result of
disturbed weather conditions over
areas thousands of miles square. By
complex teleconnected processes, the
effects of these disturbed conditions
are transmitted to areas thousands of
miles distant. Thus, the prevailing
wind systems of the globe — the
westerlies, the trade winds, and the
jet streams — may be forced into
highly abnormal patterns with con-
comitant abnormalities of weather.
Because these reservoirs of anoma-
lous heat in the ocean are deep, often
up to 500 meters, and may last for
long periods of time, the atmosphere
can be forced into long spells of
"unusual" weather, sometimes re-
sulting in regional droughts or heavy
rains over periods ranging from
months to seasons, and even years or
decades.
Potential Lines of Action — The
interface between meteorology and
oceanography is thus a promising
area which should receive more at-
tention. Several items are needed:
1. A network of observations for
both air and sea measurements
over the world's oceans, or at
least over the Pacific Ocean
where much of the world's
weather appears to be gener-
ated. This network can be a
mix of ocean weather ships, spe-
cially equipped merchant ships,
and — particularly — un-
manned, instrumented buoys
which have now been demon-
strated to be feasible. A net-
work of observations about
500 kilometers apart would be
adequate as a start; later, the
data gathered could indicate
whether a finer or coarser grid
is necessary. Satellite measure-
ments can supplement but can-
not replace these observations,
particularly the subsurface ones
which monitor the heat reser-
100
WEATHER
voirs of the sea and give in-
formation on the ocean currents.
2. "Air-sea interaction" should be
more than a catch phrase. It
is a subject which must occupy
the efforts of the best young
men in geophysics today.
Equally important is meteorolo-
gist-oceanographer interaction.
These men must not be steered
only into narrow avenues
where they lose sight of the
big problems that lie at the
heart of long-range prediction.
Special seminars and inclusion
into academic curricula of large-
scale air-sea problems on long
time-scales (months, seasons,
and decades) are necessary de-
spite the imprecise knowledge
relative to short-period phe-
nomena and short-range nu-
merical weather prediction.
3. Special attempts are needed to
bring meteorologists and ocean-
ographers together more fre-
quently in universities and
laboratories where they can
analyze oceanographic and me-
teorological data in real time,
conduct joint discussions of
what went on and is going on,
and try to predict what will go
on in subsequent months. This
will involve computers and
much research, but the research
effort will be sparked by the
satisfaction of seeing one's pre-
dictions verified. This type of
stimulus has been largely miss-
ing in the oceanographic com-
munity, where oceanographers
have had to work on restricted
problems mainly with data
months or years old or with
series of observations embrac-
ing a small area.
These same observations and pro-
cedures, and their exploitation, will
assist in most of ocean-air inquiry,
whether iterative or non-iterative
methods are employed. The ultimate
long-range prediction scheme will
probably be a combination of all
three facets -
and synoptic.
physi
c aj
Whether science will be able to
achieve appreciable skill in long-
range weather prediction should be
known in the next ten to twenty
years, providing enough trained
people are efficiently employed and
adequate data, as suggested by the
WWW and GARP programs, become
available. If, however, an unbalanced
program is embarked upon, with little
or no use made of statistics and
synoptics, it is unlikely that good,
practical long-range forecasts will be
achieved. Considering the rate of
progress already achieved despite the
complexity of the problem, the small
number of scientists who have at-
tacked it, and the inadequacy of data
and tools in the pre-computer age,
the outlook is optimistic, particularly
in view of the WWW and GARP
programs. General forecasts for pe-
riods up to a year in advance are
quite within reach; even the general
character of the coming decade's
weather may be foretold in advance.
Short-Term Forecasting, Including Forecasting
for Low-Altitude Aviation
Substantial progress has been made
during the past two or three decades
in the nonclassical, exotic areas of
the atmospheric sciences and their
applications. From a state of almost
no knowledge of the characteristics
of the atmosphere between 10 and
30 kilometers, rawinsonde networks
and high-flying, instrumented air-
craft have enabled us to produce
excellent analyses and prognoses over
most of the northern hemisphere.
Rocketsonde programs are greatly
expanding our knowledge of the at-
mosphere from 30 to 100 kilometers.
Meteorological satellites promise to
enable the meteorologist to expand
his charts to cover the globe. Fur-
thermore, the speed and capacity of
the electronic computer make it pos-
sible for his charts to be prepared in
time for practical use. The machines
produce upper-air wind and tempera-
ture fields that are as accurate as those
of an experienced meteorologist.
These and similar advances have
great practical value. For example,
sophisticated climatic techniques per-
mit introduction of the weather fac-
tor into construction planning and
other operations. Twenty years ago,
Fawbush and Miller, in Oklahoma,
began what is now a successful na-
tional program of advising the public
of threatening weather such as tor-
nadoes and hailstorms. Weather-
modification programs at military air-
fields near Spokane and Anchorage
have all but eliminated air-traffic de-
lays due to wintertime supercooled
fog at those locations.
Air-pollution research and opera-
tions promise to benefit planning for
industrial and residential areas, warn-
ing the public of impending high
pollution levels, and locating pollu-
tion sources. Simulations of at-
mospheric circulation features and
weather-modification efforts are be-
ginning to enable atmospheric sci-
entists to assess, quickly and rela-
tively economically, the effects of
deliberate or inadvertent modifica-
tions in the structure or dynamics of
meteorological features through a
wide range of scales.
Progress has also been great with
respect to sheer volume of output
in both the classical and exotic areas
of the atmospheric sciences, thanks
both to the electronic computer and
101
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
other modern methods of communi-
cation and to improvements in or-
ganization and management.
Evaluation of Forecast
Performance
The "bread and butter" products
of the meteorologists, however, are
the hour-to-hour and day-to-day
forecasts of rain, snow, and tem-
perature for the general public and
of airfield and low-level flying
weather. These have not fared so
well. Reliable tigures to demonstrate
improvement of accuracy over the
past few decades are not available
for scientific judgment of the per-
formance of the meteorological com-
munity. Statistics do exist for a
large number of forecast targets
(cities, airports) for a limited time
period and for a few selected targets
for two or three decades. However,
this sparse data sample (which may
be quite misleading) and subjective
evaluations over the years suggest
that, in an over-all sense, short-
period forecasts have demonstrated
little improvement for several de-
cades.
Routine Forecasts of Temperature
and Precipitation — Between 1942
and 1965, for example, the Chicago
office of the National Weather Service
(NWS) showed a steady improve-
ment in their combined weather and
temperature forecasts of about .33
percent per year. Large temperature-
forecast errors (10° F. or more) made
by the Salt Lake City office decreased
from one such error every 6 days
to one each 14 days. (Statistics for
the over-all temperature-prediction
capability of this office are not avail-
able.) A study of 260 NWS stations
discerned no noticeable change in
the ability to forecast rain "today"
during the first half of the 1960's,
but did note an increase of about
3 percent in the number of accurate
predictions of rain "tonight" and
"tomorrow." Scattered data such as
these suggest that the accuracy of
routine, classical forecasts of tem-
perature and precipitation has in-
creased — but only very slowly.
Hurricane and Typhoon Posi-
tions — Forecasts for special types
of weather events in some, if not
most, cases have fared better. For
example, from 1955 to 1965, the
NWS's 24-hour forecasts of hurricane
positions improved from an average
error of about 125 nautical miles to
one of about 110 nautical miles.
With regard to similar forecasts for
typhoons in the western Pacific, made
jointly by the Air Force and Navy
weather services, errors diminished
from nearly 170 nautical miles in
the mid-1950's to about 110 in 1969.
Winds — Forecasts of winds for
high-flying aircraft are in the "new"
and specialized area. Between the
early and late 1960's, wind-prediction
errors at 20,000 feet dropped from
over 15 to under 11 knots. With
regard to similar forecasts for low-
flying aircraft (e.g., at 5,000 feet)
which, although part of a specialized
activity, can hardly be classed as ex-
otic, the reduction was about one-
half that for the higher level.
Visibility and Cloud Cover — The
predictions of airfield ceiling and
visibility made by the Air Weather
Service (U.S. Air Force) are repre-
sentative of those made by other
services. Their statistics for the pe-
riod January 1968 through January
1970, compiled from the records of
200-odd airfields, show a small im-
provement, not necessarily repre-
sentative of performance improve-
ments of previous years. The accuracy
increased between 3 and 4 percent
for forecasts with time ranges of 3,
6, 12, and 24 hours. By 1970, the
forecasts were better than persistence
(no change from "time of observa-
tion") by nearly 4 percent at 3 hours
and nearly 8 percent at 24 hours.
Statistics for predictions of low-level,
in-flight clouds and weather are not
available, but are likely to be about
the same as those for airfield con-
ditions.
Verification systems used for the
kinds of forecasts discussed above
necessarily vary considerably. Opin-
ions of atmospheric scientists regard-
ing the representativeness of the
data, and the value of the methods,
also differ widely. On the whole,
however, it can be said that the
status of forecasting is about the
same for cities, airfields, and low-
level flying — on the average not
bad, on occasion seriously deficient,
and improving very slowly.
Factors Responsible for
Improvements in Forecasting
The Norwegian Theory — The Nor-
wegian air-mass and frontal theory,
developed around 1920, began to
influence meteorological research and
application on a large scale by the
late lQ30's. It represented a scien-
tific and conceptual revolution that
substantially improved the capabili-
ties of the atmospheric scientist. The
Norwegian theory was largely sub-
jective, and its application relied on
the individual skill and imagination
of trained and experienced practi-
tioners. A large part of the theory
was concerned with the distribution
and intensity of rain, surface tem-
perature and wind changes, and
cloudiness — elements that directly
influence man in his daily activities.
The Rossby Theory — A second
revolution in concept was initiated
by Rossby in the 1940's. In con-
trast to the Norwegian theory, Ross-
by's approach emphasized the im-
portance of upper-level wind and
temperature patterns, whose influ-
ences on sensible weather were broad
and ill-defined. The theory was ob-
jective and lent itself to mathematical
calculation. Almost at the outset,
after refinements by a number of
atmospheric scientists, Rossby's basic
theory began to produce usable prog-
noses of upper-level wind and tem-
perature fields. Further refinements
produced relatively large-scale fields
of vertical air-movement from which
it has become possible to predict
102
WEATHER .TING
broad areas of cloud and precipita-
tion with measurable skill. At tirst,
the necessarily large volume of data
was processed manually; with the
arrival of electronic computers in the
mid-1950's, processing could be
completed in a few hours.
This approach to research and pre-
diction caught the fancy of most
modern atmospheric scientists. Their
fascination with an objective system
that really worked — together with,
in a sense, a commitment to large,
expensive computer systems — has
brought into being a breed of sci-
entist different from those of pre-
Rossby days. This new approach has
strengths, but it also has weaknesses.
On the one hand, real progress has
been made in predicting for high-
altitude jet aircraft and even, hope-
fully, in forecasting large-scale at-
mospheric features several days
ahead of time. On the other hand,
de-emphasis of the Norwegian theory
has, if anything, degraded the mete-
orologist's ability to deal with the
small-scale atmospheric patterns as-
sociated with weather at or near the
earth's surface.
The current approach has made
some inroads on the short-range,
small-area problem. In the past three
or four years, programs employing
closer grid networks and more at-
tention to the vertical variation of
low-level meteorological elements
have increased the detail of com-
puter-produced prognoses. In recent
tests, three-dimensional air-trajectory
computer programs have increased
the accuracy of forecasts of airfield
weather by a few percent in selected
geographic areas.
Technological Contributions —
Most of the small increases in short-
period weather forecasts of the past
decade or so are not attributable to
the atmospheric sciences, however.
Thus, speeded-up communications
and computer-operations systems
have brought the "data-observation
time" closer to the "forecast time";
since short-period forecasts are more
accurate than long-period ones, an
improvement has been gained. Net-
works of observation stations have
gradually been augmented, benefi-
cially realigned, and provided with
improved instrumentation. New kinds
of data, such as those from weather
radar, have helped especially in very
short period forecasting (minutes to
hours) of clouds, precipitation, and
severe weather. Improved Air
Weather Service and other weather-
reconnaissance planes have strength-
ened the National Weather Service's
diagnostic capability; they have been
vital in pinpointing hurricane loca-
tions and specifying their intensities.
Judicious use of various stratifications
of past weather data (climatology),
again a technique requiring no mete-
orological skill in its applications, has
helped to reduce large errors in local
forecasts. There have also been ad-
vances in management practices, such
as grouping specialized meteorolo-
gists at locations where they can
work uninterrupted by telephonic or
face-to-face confrontations with their
public or military customers.
Satellites — The meteorological sat-
ellite is the most significant innova-
tion in the atmospheric sciences since
the computer. By far its greatest
contribution to date has been to
provide the meteorologist with cloud-
cover information on a global basis.
Research on the use of infrared data
obtained by satellite is growing; these
data have real potential, but they
have not yet contributed to improve-
ment in routine short-period predic-
tion.
The satellite has vastly increased
day-to-day knowledge of existing
cloud cover, which in turn has im-
proved subjectively derived circula-
tion patterns that embrace fronts,
major storm centers (including hurri-
canes), and other large-scale tropical
features, and even some of the larger
thunderstorms. It is sometimes feas-
ible to deduce upper-level winds
from observed cloud features.
The satellites assist the lorecastcr
to make predictions for an is such
as the oceans and regions of the
southern hemisphere, where data can-
not be obtained by conventional
means. In special cases — e.g., in
overseas military operations and in
flights over regions of the United
States not covered by conventional
data-gathering systems — they can
be of much, occasionally vital, aid to
the weather forecaster. Without
rapid access to good-quality, recent
satellite read-outs, however, the value
of the data for short-period forecast-
ing drops quickly.
It must be remembered that satel-
lites describe present conditions; the
atmospheric scientist is still con-
fronted with the classical problem of
predicting how conditions will change.
Furthermore, satellites do not meas-
ure parameters beneath the tops of
clouds (except for thin cirrus).
Actions to Improve the
Value of Forecasts
As noted earlier, an adequate data
base for evaluating weather forecast-
ing does not exist. A satisfactory
evaluation program also does not
exist with respect to the community
of atmospheric scientists. There are
sporadic evaluation programs, but
statistics for one kind of forecast do
not necessarily apply to other kinds
and proper assessments for long pe-
riods of years are not available. Fur-
ther, forecast-verification programs
are normally conducted by the agen-
cies that make the forecasts them-
selves, leaving open the question of
objectivity.
Operational Data Transmission ■ —
Over data-sparse areas such as re-
mote oceanic regions, airlines and
other flying agencies are already test-
ing the use of rapid, automated trans-
mission of operational data via satel-
lite to management centers. Selected
meteorological data should be in-
cluded and made available to appro-
103
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
priate weather-forecasting stations.
Similarly, in-flight weather data over
the continental United States should
be made available on call to stations
making short-period predictions for
the public, for airfields, and for low-
level flying activities. The large num-
bers of aircraft in U.S. airspace con-
stitute existing platforms with the
potential for providing much valuable
data for short-period forecasting.
As a general rule, the shorter the
period of a forecast, the more de-
tailed and dense (in three dimensions)
should be the data used in the predic-
tion process and the smaller the re-
quired area to be represented by the
data. The current rawinsonde net-
work over the United States is excel-
lent for long-period forecasts, but as
the period decreases to half a day or
less the density of observations be-
gins to leave much to be desired.
Further, upper-air wind analysis and
prognoses prepared by the computer
and used by the forecaster are
smoothed in the computational proc-
ess.
Computer Models — Efforts to pro-
duce lower-troposphere computer
models with finer and finer meshes
should be expanded, since work done
to date has already shown some
gain. Development of adequate dis-
play techniques should accompany
these efforts.
Radar and Satellite Data — In-
creased emphasis should be placed
on better utilization of radar informa-
tion, including digital processing and
use of interactive graphics to display
data and to integrate them with other
kinds of information.
Greatly increased research should
be conducted to apply meteorological
satellite data to the short-term fore-
cast problem.
The Man-Machine Mix — Consid-
erably greater effort should be di-
rected toward the man-machine mix
in forecasting. There should be
greater exploitation of the valuable —
albeit subjective — Norwegian theory
of air masses and fronts. Digital
graphics offer significant potential.
Microminiaturization should be em-
phasized in the development of new
sensing and processing equipment in
the interests of reducing lag times of
sensors as well as of reducing the
weight of equipment that must be
borne on aircraft, rockets, or bal-
loons.
Regardless of research directed at
improving short-period forecasting,
however, progress will almost in-
evitably be slow (except for new
kinds of applications) because of the
chaotic nature of smaller-scale at-
mospheric phenomena and because
meteorologists are required to state
certain kinds of prediction in prob-
abilistic terms. In some areas the
state of the art appears to have
reached a plateau; if this is so, what
are needed are breakthroughs.
104
4. CLEAR AIR TURBULENCE
Clear Air Turbulence and Atmospheric Processes
Understanding of atmospheric
processes appears to decrease rapidly
with decreasing scale or typical size
of the phenomena considered. Thus,
it has only recently been recognized
that turbulence in clear air in the
upper troposphere and lower strato-
sphere is an important part of the
energy cycle of the atmosphere.
Although motions in the atmo-
sphere at scales less than a kilometer
are often turbulent to some degree,
the occasional outbreaks of moderate
or severe turbulence that have
plagued aviation for the past decade
or more have important implications
for the study and prediction of large-
scale atmospheric motion.
These motions are a result of dif-
ferential heating. In the process of
attempting to restore a uniform dis-
tribution of heat in the atmosphere,
the motions and processes of the
atmosphere create narrow layers in
which both wind and temperature
variations are concentrated. The
sharpest of these occur in the boun-
dary layer, in the fronts associated
with weather systems, and in the
vicinity of the jet stream near the
tropopause.
In each of these regions of strong
gradients, turbulence typically occurs
when the gradients become strong
enough. The turbulent motions cause
mixing and tend to smooth the varia-
tions of wind and temperature. In
the process, a considerable amount of
heat and momentum may be trans-
ported from one region to another,
and with all turbulence there is a
conversion of kinetic energy to ther-
mal energy.
The basic cycle of events in the
atmosphere may thus be viewed as
a sequence in which:
1. Large-scale gradients created by
differential heating result in
large-scale motions.
2. The large-scale motions con-
centrate the variations caused
by this differential heating into
narrow zones which now con-
tain a significant fraction of the
total variation.
3. As the degree of concentration
increases, turbulence arises in
these zones, destroying the
strong variations and thus mod-
ifying the larger-scale structure
of the atmosphere.
In this sense, turbulence in the zones
of concentrated variation is an essen-
tial part of the thermodynamic proc-
esses of the atmosphere.
Atmospheric scientists have long
known that both the transport of
heat and momentum and the dissipa-
tion of kinetic energy were strong
in the boundary layer and in frontal
regions. The importance of these
same processes in clear air turbulence
near the jet stream is a recent dis-
covery.
Perhaps the most important prac-
tical implication of this development
concerns the feasibility of long-range
numerical weather prediction. Such
predictions cannot be reliable for ex-
tended periods unless the computer
models correctly simulate the energy
budget or energy cycle of the atmo-
sphere. It now appears likely that this
cannot be done without taking ac-
count of the role of clear air turbu-
lence — a phenomenon of too small
a scale to be revealed by present
standard sounding techniques or to
be represented directly with the data
fields used in the computer models.
The importance of clear air tur-
bulence in the energy budget is illus-
trated by its contribution to the rate
of dissipation of kinetic energy in the
atmosphere. Although the exact
value is subject to some controversy,
the total dissipation rate probably
will be somewhere in the range 5 to
8 watts per square meter, of which
2 to 3 watts per square meter prob-
ably occurs in the boundary layer.
Studies of dissipation by Kung, using
standard meteorological data, and by
Trout and Panofsky, using aircraft
data, both arrive at an estimate of
1.3 watts per square meter for the
dissipation in the altitude range
25,000 to 40,000 feet near the tropo-
pause.
Thus, despite the present uncer-
tainty of these estimates, it appears
that the region near the tropopause
contributes on the order of 20 per-
cent of the total dissipation of the
atmosphere. The rate of dissipation
in severe turbulence is about 400
times as large as that in air reported
smooth by pilots and about 20 times
as large as that in light turbulence.
The estimates of Trout and Panofsky
show that the light and moderate
turbulence contributes the major
fraction of the total dissipation in
the layer near the tropopause; fur-
thermore, their estimates show that
about equal fractions of the dissipa-
tion in this layer are probably due to
the severe clear air turbulence and
to the smooth air. (It should be
noted that the estimate of the con-
tribution of severe turbulence is un-
doubtedly too low, because pilots
attempt to avoid it if at all possible.)
Available Observational Data
Most of what is known about the
structure of clear air turbulence and
105
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
the regions in which it occurs results
from investigations motivated by its
impact on aviation. Clear air tur-
bulence has caused injuries to crew
members and passengers on commer-
cial airlines, loss of control, and
damage to aircraft structures. For
these reasons, two main types of
investigations have been carried out.
Pilot Reports — In the first type,
reports of civil and military pilots are
used in conjunction with standard
weather data in an attempt to derive
a gross climatology of both the fre-
quency of occurrence of clear air
turbulence and its association with
wind and temperature fields. These
data are biased because pilots try to
avoid clear air turbulence; further-
more, the pilot reports are subjective
and not uniform, due both to varying
pilot temperament and to varying
aircraft response to characteristics.
Instrumented Aircraft — In the sec-
ond, aircraft specially instrumented to
measure the gust velocities compris-
ing the clear air turbulence are flown
into such regions. The resulting data
have been analyzed in a variety of
ways. These programs have con-
tributed significant and valuable in-
formation about the internal physics
of the turbulent motion and about
certain aspects of its statistical char-
acteristics. The data are biased, how-
ever, by the fact that turbulence was
being sought by pilots; thus, they
cannot be used directly to establish
the frequency of occurrence of clear
air turbulence.
A more serious defect, from the
scientific standpoint, is that these
programs were conceived on the basis
of the needs of aviation and aero-
nautical engineering; they were not
designed to reveal information about
the physics of turbulence or its de-
tails or interactions with larger-scale
flows. Nevertheless, the available
data could be used for scientific pur-
poses more extensively than they
have been.
In the past few years attempts to
conduct scientific studies of the phys-
ics of clear air turbulence with spe-
cially instrumented aircraft (in some
cases with simultaneous use of
ground-based radars) have been
started in the United States, Canada,
England, and the Soviet Union. Al-
though the preliminary results from
these programs appear both promis-
ing and encouraging, no definitive
body of knowledge has yet emerged.
The problem is that the accuracy of
data required for scientific study of
the physics of clear air turbulence
and its interactions with the envi-
ronment leads to requirements for
basic sensors that severely test, or
even exceed, current instrumenta-
tion capabilities.
Theoretical Knowledge
Despite these deficiencies in the
collection of empirical data about
clear air turbulence, there does appear
to have been recent theoretical prog-
ress. Atmospheric scientists have
long suspected that clear air tur-
bulence is primarily a result of a
particular mode of fluid-flow in-
stability that occurs when there is
weak density stratification relative to
rapid vertical variation in the flow
velocity. This phenomenon has been
modeled in the laboratory by Thorpe,
seen under water in the Mediterra-
nean by Woods, and the character-
istic shape has appeared on the scopes
of radars used in turbulence studies
by Hardy, Glover, and Ottersten as
well as in a few photographs taken
when the process was made visible
by clouds. The hypothesis that clear
air turbulence is indeed a mani-
festation of this particular fluid-flow
instability provides an important con-
ceptual basis for planning the struc-
ture of empirical investigations.
Recent work has also suggested
that internal gravity waves in the at-
mosphere may be linked with the
formation of clear air turbulence. An
interesting possibility is that the
waves may be absorbed in shear
layers, and thus may act as a trigger
for the outbreak of turbulence. The
fact that gravity waves are often
generated by flow over mountains
may explain why clear air turbulence
occurs more frequently in mountain-
ous regions.
Basic Equations — Although the
basic laws that govern clear air tur-
bulence are the same mechanical
and thermodynamic ones that apply
to all fluid motion and can be ex-
pressed mathematically, there has
been little success in applying the
equations to the problem. The main
reason is that mathematical theories
that provide solutions to these equa-
tions do not seem to exist. The es-
sential difficulty is that turbulence is
a distinctly nonlinear process, and
interactions on different scales are
a crucial part of the physical phe-
nomenon.
It is precisely this that makes clear
air turbulence important to the en-
ergy cycle of the atmosphere. The
kinetic energy destroyed by the tur-
bulence comes from the kinetic en-
ergy of much larger-scale flows —
those that we attempt to predict with
numerical methods. The equations
used in the computer models apply
to averages of the variables over
quite a large region, and should in-
clude terms that express the effect
of smaller-scale motions within the
region of averaging upon the aver-
aged variables. Here again, the
mathematical form of the correct
equations is known, but some prac-
tical method must be found for rep-
resenting in the models the contribu-
tions to these terms from the intense
processes occurring in both clouds
and clear air.
This probably can be accomplished
for clear air turbulence only when a
great deal more is known about its
characteristics and its interactions
with the large-scale processes. The
most pressing need is for a thorough
empirical study with aircraft, radar,
106
CLEAR AIR TURBULENCE
and other means (perhaps laser tech-
niques). Such a study has been
recommended by the U.S. Committee
for the Global Atmospheric Research
Program.
Specific Questions About
Clear Air Turbulence
The major questions concerning
clear air turbulence now requiring
answers fall into three groups:
First, questions concerning the
origin or onset of clear air turbulence:
1. Is clear air turbulence generally
the result of a particular fluid-
flow instability? If so, what are
the crucial parameters of the in-
stability?
2. What are the typical atmos-
pheric features in which clear
air turbulence occurs and how
is their structure related to the
parameters of fluid instabilities?
(Of particular interest are the
relationships to vertical wind
shear, horizontal temperature
gradients, and the Richardson
number.)
3. Are other small-scale proc-
esses, examples being gravity
waves or local heating, impor-
tant in the formation of clear
air turbulence?
Second, questions concerning the
evolution of clear air turbulence:
1. What is the precise evolution
of the atmospheric variables at
various scales during an out-
break of clear air turbulence?
2. How can this evolution be most
economically summarized or de-
picted?
3. What are the temporal charac-
teristics of the transport of
momentum and heat, the flux
and dissipation of energy, and
the stress imposed on the
larger-scale flow during an
outbreak of clear air turbu-
lence?
4. What are the relationships be-
tween processes occurring in
one part of a patch of clear
air turbulence and those of
another? Are there relation-
ships between apparently dis-
tinct patches of turbulence?
5. What characterizes the termina-
tion of an outbreak of clear air
turbulence? What scars does
turbulence leave in its environ-
ment?
Third, questions concerning the
implication of clear air turbulence:
1. How often do patches of clear
air turbulence of various sizes
and intensity actually occur in
various regions of the atmos-
phere?
2. What is the usual intensity of
turbulence in the free atmos-
phere in regions in which flight
is sensibly smooth?
3. How important is cleai
bulence — quantitatively -
the atmosphere's energy cycle
compared to regions with the
usual intensity of turbulence
in air smooth for flight?
4. How large are the terms ex-
pressing the effects of clear air
turbulence in the usual mete-
orological equations (used for
numerical prediction) compared
to other terms?
The urgent needs of aviation and
aeronautical engineering for informa-
tion on clear air turbulence and for
reliable predictions of its occurrence
will be finally and completely satis-
fied only when a full scientific under-
standing of the phenomenon is ob-
tained. The same understanding will
permit accurate determination of
whether the effects of clear air tur-
bulence must be incorporated in
an attempt at extended numerical
weather prediction. If this is neces-
sary, and successful methods can be
found, it will mark the crossing of
a long plateau in attempts to under-
stand the interactions of large- and
small-scale motions.
The economic and social benefits
that would accrue from a capability
for long-range weather prediction
and the needs of aviation make it
imperative that the importance and
characteristics of clear air turbulence
in the general circulation of the at-
mosphere be investigated and com-
prehended.
Prediction and Detection of Wave-Induced Turbulence
The phenomenon of "clear air
turbulence" is of particular impor-
tance to man's activities within the
atmosphere because: (a) it is both a
hindrance and hazard to aviation and
(b) it accounts for roughly 20 to 30
percent of the total dissipation of the
atmosphere's energy. The latter fact,
only recently discovered, relates di-
rectly to our attempts to predict the
global circulation weeks in advance.
Without an adequate appraisal of this
significant portion of the total energy
budget, it will be impossible to model
and predict the future state of the
atmosphere.
Dimensions of the Problem
The name "clear air turbulence,"
or "CAT," has conventionally been
used to refer to turbulence occurring
several kilometers above the earth's
surface and in air that is free of
clouds and strong convective cur-
107
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
rents. But our understanding of
CAT processes, which reached a new
climax only in 1969-70, strongly im-
plies that identical mechanisms also
occur within clouds and storm sys-
tems.
Cumulative evidence is sufficiently
persuasive to conclude that CAT
occurs in internal fronts or layers in
which the air is statically stable and
across which there is strong shear of
the wind either in speed or direction.
Such conditions commonly prevail at
both warm and cold fronts marked
by clouds and precipitation. Increas-
ingly abundant aircraft incidents,
some of them fatal, also suggest that
the CAT mechanism occurs at such
frontal boundaries. The fact that
the process has not been clearly
identified as such is due to the general
assumption by pilots and meteorolo-
gists that turbulence within clouds
or storms is more commonly due to
convective- or thunderstorm-like ac-
tivity. But this assumption is un-
tenable when no direct meteorologi-
cal evidence of convective activity
exists and when aircraft undergo
forced maneuvers that can only be
associated with waves and breaking
waves; the latter are now recognized
to be the primary, if not the sole,
origin of what we have previously
called "CAT."
Newly Recognized Features — Be-
cause it now seems clear that severe
turbulence of the nonconvective va-
riety also occurs within clouds and
storms, it is fallacious to continue the
usage "clear air turbulence." And
since turbulence in both clear air and
clouds and storms owe their origin
to breaking waves, it has been pro-
posed that such turbulence be re-
named "wave-induced turbulence," or
"WIT." Unless we recognize these
important facts, we shall fail to ap-
preciate the full dimensions of the
problem. For example, while CAT
generally occurs at relatively high
altitudes, thus allowing the pilot time
to recover from a turbulence-caused
upset, severe WIT within frontal
storms may occur at very low alti-
tudes without the possibility of safe
recovery. Indeed, it is now reason-
able to suppose that many previously
unexplained fatal and near-fatal air-
craft accidents owe their origin to
WIT. Until this phenomenon is fully
appreciated both by pilots and me-
teorologists, aircraft will continue to
encounter potentially fatal hazards
without warning.
Another deceptive aspect of the
acronym "CAT" is its exclusion of
wave-induced turbulence near cloud
boundaries. This may have unfortu-
nate consequences, since it is well
known that cloud tops commonly oc-
cur at the base of temperature inver-
sions, and the latter, when marked by
sufficiently strong wind shear, are the
seat of wave-induced turbulence. In-
deed, there is reason to believe that
the presence of clouds below the in-
version will enhance the chance of
WIT above. This is because radiative
and evaporative cooling from cloud
tops induces convective overturning
and this decreases the wind shear be-
low the inversion while enhancing the
shear in and above the inversion.
Similar arguments suggest that cloud
bases may also be preferred regions
of WIT.
Finally, recent radar observations
(both ultra-high-resolution acoustic
and microwave) of stable and break-
ing waves indicate that WIT is an
almost ubiquitous feature at the low-
level nocturnal inversion and the ma-
rine inversion. On occasion, there-
fore, especially in association with the
low-level nocturnal jet, we may ex-
pect moderate to severe turbulence at
low levels. These situations would be
excluded from the present definition
of CAT, which is restricted to turbu-
lence at heights above the middle
troposphere. Equally important, how-
ever, is the recognition that WIT
plays a role in the mixing processes
at the top of the boundary layer. This
may have significant consequences for
the metamorphosis of the boundary
layer, and thus upon air-pollution
meteorology.
Hazards and Cost Implications —
All this is by way of indicating that
WIT is far more widespread than is
presently recognized. The associated
hazards are also greater; and the con-
sequences, both in terms of basic
atmospheric processes and of ultimate
operational predictability, are more
far-reaching. This is so simply be-
cause our present classification of
CAT excludes the many occurrences
at low levels that might be confused
with ordinary boundary-layer turbu-
lence, and those within and near
clouds and precipitation that are often
misinterpreted as convectively pro-
duced turbulence.
Statistics on CAT occurrence, and
its associated hazards and cost to
aviation, must therefore be viewed as
gross underestimates of the broader,
but identical, phenomenon of WIT.
Even so, the statistics compiled by
the National Committee for Clear Air
Turbulence indicate that damage to
aircraft may have cost the Depart-
ment of Defense $30 million from
1963 to 1965, to say nothing of crew
injuries or the effect of turbulence in
reducing combat effectiveness. The
committee reported a study that
showed the cost to commercial avia-
tion in 1964 to have exceeded $18
million, of which a major portion was
the increased expense caused by di-
versions around areas in which turbu-
lence was forecast or had occurred.
The WIT Mechanism and Its
Predictability
Our knowledge of the WIT mecha-
nism is substantial — at least com-
pared to the state of knowledge be-
fore 1968. A great deal more needs
to be learned, however. Newly de-
veloped observational tools promise
major advances in understanding the
WIT mechanism which should open
the way to a more realistic appraisal
of the climatology of WIT and the
physical conditions under which it oc-
curs. Together, the instruments and
the increased understanding should
lead to improved predictability, al-
108
RBULENCE
though some of our new knowledge
implies clear-cut limitations in this
respect.
The Origin of WIT — Classical
theory concerns the rapid growth of
perturbations on an internal front
(inversion) in a fluid, called Kelvin-
Helmholtz instability, which leads to
large-amplitude Kelvin-Helmholtz
(K-H) waves. The rolling-up of these
waves under the action of wind shear,
and their subsequent breaking, like
ocean waves breaking on the shore,
produces turbulence.
The process may be described sim-
ply, as follows: Suppose that we have
two fluids of different density and
that we arrange them in a stable
stratification with the lighter one on
top. Then we set the fluids in motion,
with one of the two moving faster
than the other, or in the direction
opposite to the other. If the density
change across the interface is strong
enough and the shear is not too great,
smaller perturbations will be damped
out and the interface will come back
to rest. But when the shear is strong
relative to the density gradient, the
situation is unstable and the pertur-
bations will grow rapidly with time;
vortices are created, as though a tum-
bleweed were being rolled between
two streams of air.
The condition leading to unstable
K-H waves and turbulence is that the
ratio of buoyancy forces (working to
damp vertical perturbations) to shear-
ing forces (working to enhance them)
should be less than 1. One-fourth of
this ratio is the gradient Richardson
number, Ri, which is defined as
Ri
'ft
m
a)
where g is the acceleration of gravity,
0 is potential temperature, dO/dz is
the vertical gradient of 6 (positive
whenever the atmosphere is more
stable than in the neutrally buoyant
or adiabatic case), V is the horizontal
wind velocity, and 3V/3z is the wind
shear. A result obtained in 1931 that
the critical Ri leading to K-H insta-
bility is 1/4 has been confirmed.
More precisely, Ri > 1/4 is sufficient
for stability, and Ri ^ 1/4 is neces-
sary, but not sufficient, for instability.
The entire process has been dem-
onstrated by Thorpe in laboratory
fluid experiments and by Woods in
thin, hydrostatically stable sheets in
the summer thermocline of the Medi-
terranean Sea. Both of these experi-
ments show the development of beau-
tifully formed billows, or K-H waves
which roll up into vortices and finally
break. And both demonstrate the gen-
eral validity of the critical Ri sC 1/4.
Evidence from tlie AtmospJiere —
Ludlam has observed the existence of
the K-H instability mechanism in the
atmosphere by the presence of billow
clouds, but only rarely are the com-
bination of cloud and stability con-
ditions just right to produce the
lovely roll vortices in the clouds that
are seen in the laboratory and the
sea. The observation of their com-
mon presence in the atmosphere has
awaited the use of ultrasensitive ra-
dars capable of detecting the weak
perturbations in refractive index (due
to temperature or humidity perturba-
tions) which mark sharp inversions.
Using three powerful radars at Wal-
lops Island, Virginia, Atlas and his
colleagues first reported the radar de-
tection of clear air turbulence at the
tropopause; Hicks, Angell, Hardy,
and others have reported K-H waves
and turbulence in clear air layers
marked by static stability, large wind
shear, and small Richardson number.
Undoubtedly the most striking evi-
dence of the K-H process as a cause
of WIT, and of its common occur-
rence at interval fronts, are the ob-
servations made possible by the use of
a unique new ultrasensitive FM-CW
(Frequency Modulated Continuous
Wave) microwave radar at the Naval
Electronics Laboratory Center, San
Diego. This radar is capable of one-
meter vertical resolution, roiij;
hundredfold increase over that pre-
viously available with radars of com-
parable sensitivity. With this new
tool, it has been reported that K-H
waves are a virtually ubiquitous fea-
ture of the marine inversion over San
Diego at altitudes up to about one
kilometer. Indeed, the atmospheric
K-H waves observed in this manner
are commonly as beautiful in form as
those produced in the laboratory and
observed in the sea. (See Figure IV-
10) It is worth noting that the unex-
pectedly classical form of the waves,
and their great frequency of occur-
rence within the marine inversion,
recommends the southwest coast of
the United States as an atmospheric
laboratory for studies of WIT.
What the Data Show — The fact
that the observed K-H waves are fre-
quently restricted to exceedingly thin
layers, sometimes only a few meters
in depth, and rarely with amplitudes
as large as 100 meters, explains why
the previously available high-sensi-
tivity radars of poor resolution could
not identify them. In other words,
the K-H wave structure was simply
too small to be seen and the echoes
appeared merely as thin, smooth lay-
ers marking the base of the inversion.
The new data also indicate that,
though K-H wave activity may be in
progress, the associated turbulence
will not be intense unless the waves
grow to large amplitude prior to
breaking. This has been demon-
strated by the erratic perturbations of
the height of the radar-detected layer,
indicative of moderate turbulence,
which resulted from the breaking of
K-H waves of 75-meter amplitude.
In general, waves of significantly
smaller amplitude appear not to pro-
duce appreciable turbulence.
Work now in progress shows that
the turbulent kinetic energy following
the breaking of the roll vortex of a
K-H wave is directly proportional to
the kinetic energy of the vortex im-
109
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
Figure IV-10 — WAVES AND TURBULENCE IN THE CLEAR ATMOSPHERE
Height (m)
400
- 300
- 200
1920
1930
TIME (PDT) AUGUST 6, 1969
(Illustration Courtesy of the American Geophysical Union )
Radar echoes from the clear atmosphere reveal a group of
amplifying and breaking waves in the low-level temperature
inversion at San Diego, California, as observed with a special
FM-CW radar. Waves are triggered by the sharp change of
wind speed across the interface between the cool, moist
marine layer and the warmer, drier air aloft. They move
through the radar beam at the speed of the wind at their
mean height, about 4 knots, so that crests appear at succes-
sive stages of development. In the second wave at 1919 PDT
cooler air from the wave peak drops rapidly as the breaking
begins. By 1929 PDT the layer has become fully turbulent,
and the radar echo subsequently weakens. Note, too, the
secondary waves near the crests at 1919.5, 1922, and 1926
PDT; these secondary waves give rise to microscale turbu-
lence, which causes the echo layers to be detected. The
resulting turbulence would be weak, as detected by an air-
craft. Waves of this type occur regularly in the low-level
inversion, and are believed to be similar to those which cause
the severe turbulence occasionally encountered by jet aircraft
at high altitude.
mediately prior to breaking. The
r.m.s. velocity of a vortex,
Vrms = 0.707 Aoj
= 0.707 A(tV/(z) (2)
where A is the amplitude of the roll
or wave, to its angular rotation rate
or vorticity, and cV/cz the wind
shear, thus provides a simple estimate
of the expected turbulence; prelimi-
nary tests support this hypothesis.
Moreover, it is of particular interest
that the high-resolution radar data
provide direct measures of A and its
rate of growth as well as of 5V/?z,
the shear. Similarly, the turbulence
intensity may be deducted from the
r.m.s. perturbations in the echo-layer
height subsequent to breaking. (As
yet, the inherent doppler capability of
the FM-CW radar, which would pro-
vide direct measurements of both
vertical motion and roll vorticity, has
not been implemented.)
Unresolved Problems — If Equa-
tion (2) is validated by experiments
now in progress, we may contemplate
the prediction of WIT from measure-
ments and predictions of maximum
wave amplitude and shear. But this
assumes that we shall be able to pre-
dict the latter. At this writing, the
relationship of the maximum wave
amplitude to the thermal and wind
structure of the environment is not
understood. Present K-H wave the-
ory is limited to small-amplitude
waves and their initial growth rates;
clearly, the theory needs to be ex-
tended to finite-amplitude waves. But
rapid progress is more likely to come
from experiments in the real atmos-
phere, such as those already men-
tioned, which involve somewhat more
complex wind and temperature pro-
files and interactions than are likely
to be tractable in finite-amplitude
theoretical models.
In this regard, it should also be
noted that the critical Richardson
number, Ri,- < V-i, which might be
regarded as a predictor of WIT, refers
only to the initial growth stage of
K-H instability. Since the high-reso-
lution radar shows breaking K-H
waves with amplitudes as small as 5
meters (with negligible resulting tur-
bulence) and as large as 100 meters
(with appreciable turbulence), a seri-
ous question is raised as to the verti-
cal scales over which thermal stabil-
ity and shear — and so Ri — need to be
measured. Surely, the present data
imply that Ri must be observed on
scales of a meter or less to account
for the small-amplitude waves. But
it is not so clear that measurements
with resolution of 10 to 100 meters
or more, such as those available from
present-day radiosondes, would be
adequate to predict the occurrence of
larger-amplitude waves. What, for
110
CLEAR \ . , lENCE
example, happens to a growing un-
stable wave in a thin stratum when it
reaches a dynamically stable layer in
which Ri is significantly greater than
Vi ? We do not know. This is one
of many important questions that
needs to be answered by further re-
search.
Other aspects of the new radar ob-
servations that are relevant to flight
safety as well as to aircraft investiga-
tions of WIT and to its predictability,
are: (a) the sharp vertical gradations
in turbulence intensity (i.e., some-
times the turbulence is restricted to a
stratum no more than a few tens of
meters thick) and (b) the inter-
mittancy of K-H waves and turbu-
lence.
It is not surprising that one air-
craft experiences significant turbu-
lence while the next one encounters
none in the same region. While the
radar observations demonstrate that
the base of the inversion and subsidi-
ary sheets within it are the seat of
K-H wave activity, their breaking is
self-destructive in that the shear and
stability to which they owed their
origin are decreased, and Ri thus in-
creased above its critical level. Ac-
cordingly, the breaking action acts as
an escape valve to release the pressure
for K-H activity, and turns the waves
and turbulence off. On the other
hand, the larger-scale atmospheric
processes work to restore the initial
conditions, and new K-H waves are
triggered.
All this speaks to the difficult ques-
tions of aircraft experiments directed
to observing the initial conditions for
WIT, the energy budget involved,
and, indeed, its entire life cycle. Pre-
cisely where and when should the
measurements be made and how are
they to be interpreted in the light of
WIT's great spatial and temporal vari-
ability? Clearly, such experiments
should preferably be conducted si-
multaneously with a radar capable of
"seeing" the waves and turbulence di-
rectly.
Prospects for Prediction — The prior
discussion raises serious doubts as to
the ultimate achievement of pinpoint
forecasts of WIT in either space or
time. While one may expect, eventu-
ally, to be able to predict the medium-
to large-scale processes that work to
develop and sharpen internal fronts
and shear, many presently unobserv-
able small-scale phenomena (gravity
waves, orographic lifting and tilting,
convective motions, and such) will
operate to reduce Ri to its critical
value locally and trigger wave activity
here and there. Accordingly, while
we may expect significant improve-
ments in the predictability of the
heights of internal surfaces, and thus
in the heights at which WIT is likely,
and probably in the predicted in-
tensity as well, the actual forecast will
probably remain a probabilistic one
for many years to come. We should
therefore direct a good share of our
attention to the remote-probing tools
that are capable of detecting both the
internal surfaces and the occurrence
of waves and turbulence. As in the
case of radar detection of thunder-
storms, such observations are likely
to provide the best short-term predic-
tions of WIT for the foreseeable fu-
ture.
Instrumentation for Detecting WIT
Although we have spoken exten-
sively of the capability of ultrasensi-
tive high-resolution radar techniques
in detecting WIT, a few additional re-
marks need to be made concerning
actual warning devices.
Ground-Based Devices — High-
resolution FM-CW microwave radar
is an obvious candidate for this task.
At present, however, it is limited to a
detection range (based on over-all
sensitivity in detecting clear air in-
versions) of about 2 kilometers. An
increase of range to 15 kilometers is
attainable with available state-of-the-
art components. This would accom-
plish the detection of clear-air WIT
throughout the depth of the tropo-
sphere. A network of such st,
across the nation, with fixed, ver-
tically pointing antennas, is econom-
ically feasible. Fortunately, the sig-
nificant internal fronts at which WIT
occurs are horizontally extensive, so
that detection of waves and turbu-
lence at one or more stations would
indicate the layers affected and the
likelihood of WIT at the same height
(or interpolated height for sloping
layers) in between stations. (Note that
we emphasize the need for observa-
tions with a high degree of vertical
resolution, capable of detecting the
suspect layers and measuring the
amplitude and intensity of breaking
waves.)
Airborne Radar — With regard to
the use of high-resolution FM-CW
microwave radar on board aircraft for
purposes of detecting and avoiding
WIT along the flight path, the 15-
kilometer range capability would be
inadequate to provide sufficient warn-
ing even if a high-gain antenna of the
required dimensions (10' to 15' effec-
tive diameter) could be accommodated
in the aircraft. Moreover, since the
vertical resolution in such a use-mode
would correspond to that of the beam
dimension rather than the available
high-range resolution, the radar could
not discern wave amplitude and
heights with precision. However, the
use of such a radar in both down-
ward- and upward-looking directions
(from large antennas fitted within the
fuselage structure) does appear feas-
ible. Clear-air WIT could then be
avoided by detecting the heights of
internal surfaces and K-H wave ac-
tivity above and below flight level
and assuming continuity of layer
slope. Whether or not such a system
should be adopted depends on cost/
benefit/risk ratios. The installation
of a $100,000 radar seems warranted
when aircraft carry more than 200
passengers. Certainly, it should be
adopted for experimental purposes in
connection with WIT research. The
potential benefits of airborne high-
resolution radar to both military and
commercial aviation could then be
better evaluated.
Ill
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
High-Resolution Acoustic Radar is
another candidate for clear-air WIT
detection from ground-based stations.
Such radars have detected thin inter-
nal surfaces and stable and breaking
wave activity to heights of 2 kilo-
meters. The potential to reach 15
kilometers in the vertical direction
can probably be realized, although the
effect of strong winds aloft on the
refraction of the acoustic beam re-
mains an open question. Unfortu-
nately, acoustic radar cannot be used
on board fast-flying aircraft because
of the slow speed of sound and the
high acoustic noise levels.
Future Teclmologx/ — Finally, a real
hope still remains for the develop-
ment of a coherent laser radar (or
LIDAR) sufficiently sensitive to de-
tect the small background concentra-
tions of aerosols in the high tropos-
phere and capable of measuring
turbulence intensity through the dop-
pler velocities. Although a theoretical
feasibility study of such a device in
1966 indicated that the then available
LIDARs could not accomplish the
task, more recent developments in
laser technology may now make such
a system feasible. The National Aero-
nautics and Space Administration is
presently conducting research and de-
velopment along these lines.
A Note on Acoustic Monitoring
As is well known, the propagation
of sound waves through the atmos-
phere is strongly affected by wind,
temperature, and humidity. The pos-
sibility therefore exists that measure-
ments of the propagation of sound
waves could be used to derive infor-
mation on important meteorological
parameters.
The potential of these methods has
been analyzed and some experimental
results published. It has shown that
acoustic echoes can readily be ob-
tained from the atmospheric turbu-
lence and temperature inhomogenei-
ties always existing in the boundary
layer of the atmosphere. The equip-
ment required is relatively simple; it
involves a radar-like system in which
pulses of acoustic signal, usually
about 1kHz in frequency, are radi-
ated from an acoustic antenna, with
echoes from the atmospheric structure
obtained on the same or on a second
acoustic antenna.
This field of acoustic echo-sounding
of the atmosphere is very new and
appears to hold considerable promise
for studies of the boundary layer of
the atmosphere — i.e., the lowest sev-
eral thousand feet. Specifically, re-
search is now being undertaken to
identify its usefulness for the quanti-
tative remote measurement of wind,
turbulence, humidity, and tempera-
ture inhomogeneity. If, as expected,
the technique is shown capable of
measuring the structure of the bound-
ary layer and the vertical profiles of
these meteorological parameters, it
will represent a major breakthrough
in remote measurement of the atmos-
phere, which should be of great value
to meteorological observations and
research. Its primary application is
likely to be in the monitoring of
meteorological parameters in urban
and suburban areas, for use by air-
pollution and aviation agencies. In
addition, it is already providing the
research worker with totally new in-
sight into the detailed structure and
processes controlling the atmospheric
boundary layer in which we live.
112
5. URBAN EFFECTS ON WEATHER AND CLIMATE
Urbanization and Weather
For centuries, man has speculated
that major battles, incantations, large
fires, and, lately, atomic explosions
could affect weather, although he
made no serious scientific attempts
to modify weather until 25 years ago.
Except for a few localized projects
involving precipitation increases and
fog dissipation, however, man's in-
tentional efforts have yet to pro-
duce significant, recognized changes.
Rather, the major means whereby
man has affected weather have been
inadvertent — through his urban en-
vironment.
Growing Awareness of the Problem
As long ago as 700 years or more,
London had achieved a size great
enough to produce a recognizable ef-
fect on its local weather, at least in
terms of reduced visibility and in-
creased temperature. Since major ur-
ban areas became prevalent in Europe
following the Industrial Revolution,
Europeans have directed considerable
scientific attention to this problem
of urban-induced weather change.
Now that major urban-industrial com-
plexes exist in many countries, world-
wide attention has grown rapidly,
particularly in the United States,
where the growth of megalopolitan
areas during the past ten to thirty
years has brought with it increasing
public and scientific awareness of the
degree and, in some cases, the seri-
ousness of urban effects on weather.
Recent studies documenting signif-
icant urban-related precipitation in-
creases in and downwind of Chicago,
St. Louis, and industrial complexes in
the state of Washington have further
focused scientific and public attention
on the urban-weather topic and its
considerable potential.
Certainly, even the casual observer
is aware that visibility is more fre-
quently restricted in a major urban
complex than in rural areas, and that
this has come from smoke, other con-
taminants, increased fog, and their
additive, smog. Most Americans are
now aware that the temperature with-
in a medium-to-large city is generally
higher at any given time of the day
or season than it is in rural areas.
This temperature effect has been rec-
ognized and measured for many
years, since its measurement, at least
at the surface, is relatively easy. "Heat
islands" for many cities of various
sizes have been well documented.
Urban areas also act as an obstacle
to decrease winds near the surface,
to increase turbulence and vertical
motions above cities, and to create,
occasionally, a localized rural-urban
circulation pattern. There have been
enough descriptive studies, further-
more, to reveal that many other
weather conditions are also being
changed, often dramatically, by urban
complexes. Although available re-
sults indicate that urban-induced
weather changes are restricted to the
cities and their immediate downwind
areas and have little effect on macro-
scale weather conditions, the "urban
flood" and advent of the megalopolis
could conceivably lead to significant
weather changes over large down-
wind regions.
Value Judgments — The question
of desirability of the weather changes
wrought by urbanization has only re-
cently been considered. The fact that
many of the urban-induced changes
have occurred gradually has not only
made them difficult to measure quan-
titatively within the natural variabil-
ity of weather, but has also made
them less obvious and, therefore, un-
wittingly accepted by the urban
dweller. Now that urbanization is
nearly universal, American citizens
have suddenly become aware of
many of the urban-induced weather
changes. In general, such changes as
increased contaminants, higher warm-
season temperatures, lower winds,
added fog, increased thunder and hail,
added snowfall, and decreased visibil-
ity are considered undesirable. Cer-
tain urban-related weather changes
are desirable, however, including
warmer winters and additional rain-
fall to cleanse the air and to add water
in downwind agricultural areas.
In summary, then, with respect to
their effects on weather, urban areas
sometimes act as volcanoes, deserts,
or irregular forests; as such, they pro-
duce a wide variety of weather
changes, at least on a local scale, and
these changes can be classed as bene-
ficial or detrimental depending on the
locale and the interests involved.
Type and Amount of
Weather Change
The changes in weather wrought
by urbanization include all major
surface weather conditions. The list
of elements or conditions affected in-
cludes the contaminants in the air,
solar radiation, temperature, visibil-
ity, humidity, wind speed and direc-
tion, cloudiness, precipitation, atmos-
pheric electricity, severe weather, and
certain mesoscale synoptic weather
features (e.g., it has been noted that
the forward motion of fronts is re-
tarded by urban areas). (See Figure
IV-11)
The degree of urban effect on any
element will depend on the climate,
113
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
Figure IV— 1 1 —WEATHER CHANGES RESULTING FROM URBANIZATION
Cold
Warm
Annual
season
season
(percent)
(percent)
(percent)
Contaminants
+ 1000
+2000
+500
Solar Radiation
-22
-34
-20
Temperature
+3
+ 10
+2
Humidity
-6
-2
-8
Visibility
-26
-34
-17
Fog
+ 60
+ 100
+30
Wind Speed
-25
-20
-30
Cloudiness
+8
+5
+10
Rainfall
+ 11
+ 13
+ 11
Snowfall
±10
±10
—
Thunderstorms
+8
+5
+ 17
The table summarizes changes in surface weather conditions attributable to urban-
ization. Changes are expressed as percent of rural conditions.
nearness to major water bodies, on
topographic features, and city size
and components of the industrial
complex. Furthermore, the amount of
effect on the weather at any given
time depends greatly on the season,
day of the week, and time of day.
Thus, urban solar radiation is de-
creased much more in winter than
summer; is decreased on weekdays;
and is decreased more in the morning
than in the afternoon. Temperature
increases resulting from the heating
of urban structures are much greater
in winter than in summer; hence, the
average urban air temperature in win-
ter is 10 percent higher than that in
rural areas, whereas in summer it is
only 2 percent higher. However, ur-
ban temperatures during certain sea-
sons and weather conditions can be
as much as 35 percent higher or 5
percent lower than nearby rural tem-
peratures.
It should be emphasized that op-
posite types of changes in certain
weather conditions are produced at
different times. For example, fog is
generally increased by urbanization,
although certain types of fogs are ac-
tually dissipated in large cities. Wind
speeds are generally decreased, but
they increase in some light wind con-
ditions. Snowfall is generally in-
creased by urban areas, but under
certain conditions the city heat actu-
ally melts the descending snow, trans-
forming it into rain.
Current Scientific Status
Most studies of urban effects on
weather have been descriptive and
based on surface climatic data. Fur-
thermore, only a few studies have at-
tempted to investigate the causative
factors and the physical processes in-
volved in urban-produced weather
changes. Without careful investiga-
tions of the processes whereby urban
conditions affect the weather, there is
little hope for developing an adequate
understanding and, hence, predictive
capabilities.
Data Base — The present data base
is woefully inadequate for studies
of most urban-affected weather ele-
ments. Two-dimensional spatial de-
scriptions of urban effects on weather
elements are now adequate only for
temperature patterns. Data for
weather changes in the vertical are
totally inadequate for temperature as
well as for all other weather elements.
Descriptive types of urban-weather
studies based on existing historical
records tend to be seriously limited in
their spatial information. For instance,
studies of urban-rural fog differences
have typically been based on surface
values from a point in the central city
and one at the airport; although these
may indicate a 30 percent difference,
they fail to describe the horizontal
distribution of fog over the urban
or rural environs.
Unfortunately, adequate descrip-
tions of the surface weather changes
are not available for most metropoli-
tan areas of the United States. Study
of the urban-weather relationships in
the United States has been much
more limited than that in Europe be-
cause the surface weather-station net-
works in and around American cities
have been too sparse. Information
useful for such practical problems as
city planning can be developed for
major U.S. metropolitan centers only
on the basis of thorough comparative
studies of data from denser urban-
rural surface networks than currently
exist around most American cities.
Instrumentation — Satisfactory
tools to perform needed monitoring
and study of urban-induced weather
changes are available. Major advances
in the development of airborne equip-
ment to measure meteorological vari-
ables and aerosols provide the poten-
tial for obtaining the vertical data
measurements needed to develop
time-dependent, three-dimen-
sional descriptions of the weather ele-
ments around cities. Field studies of
the airflow and vertical temperature
distributions at Cincinnati and Fort
Wayne, Indiana, have used these new
instruments and techniques in pio-
neering research.
Theory and Modeling — The basic
theoretical knowledge and formulas
exist for understanding the atmos-
pheric chemistry and physics in-
volved in urban-weather relation-
ships. Ultimately, studies of the
urban factors that affect weather
elements will provide the inputs
114
URBAN EFFECTS ON ' IATE
needed to model the urban-weather
system. However, this will require
three-dimensional, mesoscale numeri-
cal models (not currently available)
and computers (soon to be available)
with the capacity to handle them.
Practical Implications of
Urban-Induced Weather Change
Regional Planning — The factors
that produce undesirable weather
changes clearly need to be assessed,
and hopefully minimized, in planning
and building new urban areas and
redeveloping old ones. For instance,
the ability of large urban-industrial
complexes to produce thunderstorms,
heavy rains, and hailstorms in and
downwind of the complexes has par-
ticular importance in hydrologic de-
sign for urban storm drainage and
in agricultural planning.
Pollution — Knowledge of the
urban-induced wind and rainfall
changes apt to occur with various
weather conditions is also required
for determining whether these
changes will materially affect pollu-
tion levels. The generally expected
decrease in winds and poorer ventila-
tion are certainly undesirable, but ur-
ban-increased rainfall is beneficial in
this connection. Such knowledge
would also help in improving local
forecasting, thus enabling man to do
better planning of his outdoor ac-
tivities.
Weather Modification — Study of
the exact causes of various urban-
produced weather changes can also
be expected to help man in his efforts
to modify weather intentionally. In
particular, the study of the conditions
whereby urban complexes affect pre-
cipitation processes could generate
needed information about the weather
conditions appropriate for seeding,
the types and concentrations of ef-
fective seeding materials, and poten-
tial rainfall changes expected beyond
the areas of known urban-related
increases. Continuing disagreements
over evaluation of man-made changes
and the types of physical techniques
and chemical agents of modification
reveal the need for proper study of
these aspects during urban field in-
vestigations and analyses.
The economic aspects of this prob-
lem are hard to assess but are surely
significant. Reduced visibility, more
fog, and added snowfall directly and
indirectly restrict human activity.
The damages to health, property, and
crops resulting from added contami-
nants, less sunshine, higher tempera-
tures, and less ventilation can be
serious. National economic losses at-
tributable to urban-induced weather
changes are inestimable.
Requirements for Scientific
Activity
The interactions of urban-produced
weather changes with such matters as
agriculture and hydrology, and with
ecology, are only partly understood,
since the inadvertent aberrations are
frequently within the limits of natural
variability of weather. For instance,
the increase in crop yields resulting
from urban-increased rainfall could
be easily and accurately assessed,
whereas the effect on crop yields of
increased deposition of urban con-
taminants into soils cannot currently
be assessed without special studies.
Our knowledge and understanding of
the interactions of weather changes
with man and society are almost
totally lacking. The legal and social
ramifications are barely understood,
although the threats of damage to
property, crops, health, and safety
from such changes as increased con-
taminants, more fog, less sunshine,
and higher temperatures are now
clear. Certainly, the responses to
inadvertent weather changes provide
an opportunity to study and assess
potential human reaction to planned
weather modification. The only
means of fully assessing the urban-
modification effect of each weather
element in a given locale, however,
is to measure all elements in three
dimensions.
Adequate measurement and under-
standing of the interactions between
urban factors and atmospheric con-
ditions that produce, for example, a
10 percent rainfall increase in one
urban complex should lead to rea-
sonably accurate predictions of the
precipitation changes in most com-
parable cities where routine measure-
ments of the urban factors exist or
could easily be performed. Indeed,
major projects to study the urban
conditions that change weather ele-
ments are sorely needed at several
cities, each of which should be repre-
sentative of basically different North
American climates and urban com-
plexes so that the results could be
extrapolated to other cities. A min-
imum national effort would consist
of a thorough field project in one
city that is representative in size and
climate of several others.
Such a project would be more
meaningful if relevant interdiscipli-
nary projects involving the physical
and social sciences were conducted
simultaneously.
To achieve meaningful, three-
dimensional measurements of weather
and urban conditions will require
marshalling of instrumentation and
scientific effort to create dense net-
works of surface instruments heavily
supplemented by vertical measure-
ments obtained by aircraft, balloons,
and remote probing devices. The
scientific skills, personnel, and fa-
cilities necessary to explain and pre-
dict most facets of this topic exist,
but they have yet to be focused on
it. Answers exist in relation to sev-
eral basic questions concerning the
urban-weather topic, but more con-
centrated study is needed in the next
five years. No serious effort has
been made to describe the interac-
tion between urban-induced weather
changes and man, and this, too, is
urgently needed. If performed, these
studies should provide information
adequate to modify some of the un-
desirable weather changes within ten
years.
115
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
The Influence of Urban Growth on Local and Mesoscale Weather
The fact that large human settle-
ments change the atmospheric con-
ditions in their immediate vicinity
has been recognized for over a cen-
tury. Up to very recently, however,
it was considered that these influences
were strictly local in character. Anal-
ysis in depth has shown that this
may not be the case at all and that
urban influences on the atmosphere
may well reach considerably beyond
the urban confines.
The causes for effects of towns on
weather and climate are easily traced.
First, human activities, especially
combustion processes, produce heat.
In some cities in northern latitudes
during the winter this added energy
may be a sizable fraction of the
solar energy impinging on the same
area. In recent years, airconditioning
has also been adding heat to the air
in summer by dumping the excessive
indoor heat into the surrounding at-
mosphere.
The energy balance is further al-
tered because urban surfaces replace
vegetation of low heat capacity and
heat conductivity with stony surfaces
of high heat capacity and heat con-
ductivity. These same urban sur-
faces also alter the water balance.
Rain runs off rapidly, diminishing
the natural system of evaporation
and evapotranspiration, not only fur-
ther altering the energy balance by
reducing evaporative cooling but also
throwing great burdens on drainage
and runoff systems at times of intense
precipitation.
Compact areas of buildings and
dwellings also alter the natural air
flow. They create considerable aero-
dynamic roughness. This may cause
changes in the low-level wind profiles
up to several thousand feet in the
atmosphere.
Most important, probably, is the
effect of cities on atmospheric com-
position, not only locally but even
for many dozens, if not hundreds, of
miles downwind. Literally hundreds
of different chemical compounds from
industrial and combustion processes
are blown into the atmosphere. The
blind faith of the past trusted that
friendly air currents would dilute and
dispose of them harmlessly. Yet
many of these admixtures have be-
come semi-permanent residents of the
atmosphere, where they undergo fur-
ther chemical change through the im-
pact of solar radiation and by inter-
action with the water vapor in the
atmosphere.
Meteorological Changes and
their Consequences
Many of the meteorological altera-
tions in urban areas have been quan-
titatively assessed. Most of them are
universally agreed to. In enumerat-
ing them we proceed from the sim-
pler to the more complex and, almost
in parallel, from the noncontrover-
sial to the controversial aspects of the
problem.
The Water Balance — It is per-
fectly obvious that, by replacing the
naturally spongy vegetative surface
with impervious roofs, parking lots,
and streets, any falling rain will
quickly run off. Indeed, urban drain-
age systems are designed to carry
the waters rapidly into streams and
rivers. The consequence is that flood
waters may gather more rapidly and,
in case of excessive rainfalls, not only
increase crests but also cause rapid
flooding of low-lying districts in ur-
ban areas. The lag time of flood
runoff may be cut in half by the
impervious areas.
Heat Islands — The excess energy
production of a city and its altered
heat balance, because of changes in
albedo and heat characteristics of
the man-made surface, creates one
of the most notable atmospheric
changes in urban areas. It has been
given the very descriptive label "heat
island." This term designates a tem-
perature excess that covers the urban
area. It is most pronounced in the
sectors of highest building and popu-
lation concentrations; on calm, clear
nights it can reach or even exceed
10 Farenheit compared with rural
surroundings. (See Figure IV-12) Re-
cent experiments have shown that a
single block of buildings will produce
a measurable heat-island effect. At
the same time, the reduced evapora-
tion caused by rapid runoff and re-
duced vegetation as well as this tem-
perature increase reduces the relative
humidity at the surface.
Wind Circulation — The previously
mentioned increase in surface rough-
ness causes decreased wind speed at
the surface. The heat island also
induces wind convergence toward the
urban area. In daytime, the highly
overheated roof and black-top sur-
faces create convective updrafts, es-
pecially in summer. The updrafts
induce a higher degree of cloudiness
over the city and contribute to the
release of showers over the city.
At night, inversions of temperature
form over the rural and suburban
areas while temperature-lapse con-
ditions continue in a shallow layer
over the city core. This temperature
distribution induces a closed circu-
lation system within a metropolitan
area, which in turn contributes to
concentrations rather than dispersion
of pollutants when the general wind
circulation is weak.
Solar Radiation — Pollutants act in
an important way on the incoming
solar radiation. The aerosol absorbs
and scatters the solar radiation, af-
fecting principally the shorter wave-
lengths. This means that the long-
wave ultraviolet radiation is radically
weakened and its possible beneficial
effects as killer of germs and activa-
tor of vitamin D in the human skin
116
URBAN EFFECTS ON WEATHER AND CLIMATE
Figure IV-12 — HEAT ISLAND EFFECT
(Illustration Courtesy of the American Meteorological Society)
The figure shows the isotherm pattern for 2320 PST on 4 April 1952 superimposed
on an aerial photograph of San Francisco. The relation between the air tempera-
ture measured 2 meters above the surface and urban development is evident. A
temperature difference of 20°F. was observed on that calm, clear night between the
densely built-up business district (foreground) and Golden Gate Park (left rear).
are reduced or eliminated. At the
same time, these actinic rays cause
a large number of photochemical
reactions in the welter of pollutants.
Many of them lead to obnoxious sec-
ondary products such as ozone, which
irritates mucous membranes, and
other equally undesirable products.
They cause notable reduction in vis-
ibility, which is not only aesthetically
objectionable but often detrimental
to aviation. Increased haze and fog
frequency, compared with the natural
environment, is a man-made effect,
a fact that becomes impressive be-
cause it is demonstrably reversible.
In some cities (e.g., London) where
the number of foggy days had grad-
ually increased over the decades, a
determined clean-up of domestic fuels
and improved heating practices led
to immediate reduction in the fog
frequency.
Precipitation — Much less certainty
exists about both the local and more
distant effects of city-created pol-
lutants on precipitation. The already
mentioned increased shower activity
in summer has probably little or
nothing to do with the pollutants.
It is primarily a heat effect, with
water-vapor release from combustion
processes perhaps also playing a role.
But we do have a few well-docu-
mented wintertime cases when iso-
lated snowfalls over major cities were
obviously induced by active freezing
nuclei, presumably produced by some
industrial process. There is no in-
contestable evidence that over-all
winter precipitation over urban areas
has increased, but most analyses
agree that total precipitation over
cities is about 5 percent to, at most,
10 percent greater than over rural
environs, even if all possible oro-
graphic effects are excluded. More
spectacular increases observed in the
neighborhood of some major indus-
trial-pollution sources are probably
the effect of sampling errors inherent
in the common, inadequate rain-
gauge measuring techniques.
Even so, there is major concern
about the very possible, if not al-
117
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
ready probable, effects of city-pro-
duced pollutants on precipitation
processes. One of them can be
caused by the high emission rates
of minute lead particles from the
tetraethyl-lead additive to gasoline.
Some of these particles combine with
iodine brought into the atmosphere
primarily from oceanic sources to
form lead-iodide. This compound
has been shown to form very efficient
and active freezing nuclei, which can
trigger precipitation processes in only
slightly sub-cooled cloud droplets.
The lead particles are so small that
they will stay in suspension for long
distances and thus trigger precipita-
tion at places far removed from the
sources of the lead. Even more
ominous could be the swamping of
the atmosphere by condensation nu-
clei. These are produced in urban
areas in prodigious amounts in con-
centrations surely two orders of mag-
nitude higher than in uncontaminated
air. There are literally hundreds of
thousands of these nuclei in a cubic
centimeter, and even the most hygro-
scopic of them competes for the
available moisture in the air. The
more nuclei there are, the more likely
it is that the cloud droplets that form
will be very small because of the
large number of competing centers
around which condensation occurs.
Small cloud droplets have more dif-
ficulty in coalescing and forming rain
than large droplets. Hence it is quite
possible, although not proven beyond
doubt, that in some urban areas or
downwind from them a decrease in
rainfall could occur. This is one of
the effects requiring careful watch in
future research.
Atmosplieric Stagnation — When
weather conditions favor slight winds
and surface temperature inversions,
air layers in metropolitan areas be-
come veritable poison traps. These
can lead to the well-known health-
endangering pollution episodes. With
a number of metropolitan areas in
close proximity, a slight ventilation
will waft pollutants into the next
series of settlements within a few
hours or days and aggravate the situ-
ation there. This type of accumula-
tion has not been adequately investi-
gated either. But the whole area of
the United States east of the Ap-
palachians from northern Virginia to
southern Maine may be affected by
cumulative pollution effects. There
are also other megalopolitan areas in
the country that may need similar
attention. Computer simulation of
such atmospheric-stagnation periods
has made some progress but is still
severely restricted by the inadequacy
of the mathematical models and the
lack of sufficient actual observations.
Many of the micrometeorological
alterations brought about by urbani-
zation have been well documented in
a number of cities. They have re-
cently been followed, stey by step, in
a rural area that is in the process of
becoming urbanized — the new town
of Columbia, Maryland, where popu-
lation density has increased from a
few hundred to a few thousand in-
habitants and will increase to a hun-
dred thousand in the current decade.
Many of the characteristic changes
in temperature, wind, humidity, and
runoff are already observable. This
continuing study in a planned, grow-
ing community may greatly further
our knowledge of the micrometeoro-
logical changes.
Implications for Town Planning
It is proper to ask whether we can
turn this knowledge to use in future
town planning and redevelopment of
older cities. The answer is affirma-
tive. Natural environments charac-
teristically have a varied mosaic of
microclimatic conditions, most of
which are destroyed by urbanization.
The detrimental effects are primarily
introduced by compact construction
with few interruptions, creating an
essentially new surface of roofs at
which energy interactions take place.
In many urban areas, vegetation has
been sharply diminished or even com-
pletely eliminated. Reversal of this
trend will bring about a desirably
diversified pattern of microclimate.
Two tall buildings with large green
and park areas surrounding them are
far preferable to the typical row
house or walk-up slum configura-
tion. The open construction charac-
teristic of suburban areas has caused
little climatic deterioration of the
environment.
Air pollution will remain a prob-
lem. There is some merit in using
tall stacks for the effluents from
stationary sources. Appropriate loca-
tion, predicated on the general re-
gional airflow patterns, is indicated
for industrial sources of pollutants.
There is little substantive knowledge
on possible amelioration of pollutants
from mobile sources through highway
routing, construction, elevation, or
other engineering techniques. Con-
trol at the source seems to offer the
only tenable solution over the long
run.
Too little is yet known about the
sinks of pollutants in urban areas,
although shrubbery and insensitive
plants seem to offer some help by
intercepting particulates.
Urban Effects on Weather — the Larger Scales
The possibility that human activi-
ties might be modifying large-scale
weather patterns or even the global
climate has received much publicity.
The present state of atmospheric sci-
ence does not allow either firm sup-
port or confident refutation of any
of the effects which have been pos-
tulated.
118
URBAN EFFECTS ON WEATHER AND CLIMATE
There is no doubt that cities modify
their own weather by the local pro-
duction of heat and addition of ma-
terial to the atmosphere. "Material"
includes water vapor (H_0) and car-
bon dioxide (COu) as well as the
gases and particulates commonly
classed as pollutants. City tempera-
tures exceed those of similarly ex-
posed rural areas, particularly at
night, but the most noticeable change
is in the solar radiation reaching the
ground, which is typically about 10
percent below that of upwind sur-
roundings. In considering the extent
to which effects on weather may
overstep the city boundaries, it is
convenient to look at three scales —
local, regional, and global. "Local"
refers to effects downwind of the
city at distances up to about 100
miles; "regional" to subcontinental
areas of the order of 1,000 square
miles; and "global" to the whole
world.
Local Effects
Local effects include deterioration
of visibility and reduction of solar
radiation, which are not in ques-
tion. At 100 miles distance, in New
England, one knows when the wind
is blowing from New York City. This
does not, in general, have repercus-
sions on the other weather factors
that are large enough to be estab-
lished by examining weather records.
If there are such effects they are
small and probably lost in the general
variance, although no very sophisti-
cated search has been made — for
example, among satellite cloud pic-
tures — to verify that speculation.
In two or three instances, it has
been claimed that an increase of
precipitation downwind of cities has
been established. The best known
example is at La Porte, Indiana, where
an apparent considerable excess of
precipitation over surrounding areas
has been associated with industrial
activity (particularly steel mills) in
the Chicago and Gary, Indiana, areas.
This seemed to be a clear-cut case,
but the skill and/or objectivity of
the one observer whose record estab-
lished the effect has recently been
questioned (with supporting evidence)
by other climatologists. In the other
cases that have been discussed, in-
cluding recent claims of an increase
of shower activity downwind of pulp
plants in Washington state, the statis-
tical evidence offered in support of
the hypothesis of modification is less
convincing than that for La Porte.
Physically, there is doubt whether
any precipitation increase that might
occur would be an effect of cloud
seeding by particulate pollutants or
of the increased triggering of convec-
tion by the heat and moisture sources
of the city. The latter explanation is
gaining favor.
Regional Effects
On the regional scale there is gen-
eral agreement that atmospheric tur-
bidity — a measure of the extinction
of solar radiation — has increased
over the past fifty years in western
Europe and eastern North America,
even in locations as remote from
cities as can be found in these areas.
Again, there is no indication that
the reduction in solar radiation reach-
ing the ground has had any effect
on other weather elements. Such
connections are extremely difficult to
establish, for reasons which will be
discussed later when we consider
global effects.
There is, however, one possible
regional effect of pollution that is
causing international concern, though
it would not traditionally be con-
sidered a "weather" phenomenon.
This is the deposition in precipitation
of pollutants transported hundreds
of miles from their source, perhaps
across international boundaries. The
best-known case is the occurrence in
Scandinavia of rainfall with an un-
usual degree of acidity which has
been attributed to the transport of
pollutants emitted in Britain and Ger-
many. A similar geographical and
meteorological situation exists in the
northeastern United States, where the
situation might repay investigation.
Persistently acidic rain or snow might
have long-term effects on forest ecol-
ogy and lead to reduced productivity
in forest industries. The connection
between the observation and its pre-
sumed cause is simply the fact that
no other explanation has been con-
ceived. Statistical or physical links
have not been demonstrated — in-
deed, our current ignorance in the
fields of atmospheric chemistry and
microphysics precludes a convincing
physical link. This is potentially one
of the most serious of the currently
unsolved scientific environmental
problems.
Global Effects
The possible modification of cli-
mate by industrial effluents has been
under serious scientific discussion for
more than thirty years and the ex-
tent, nature, and intractability of the
underlying problems is now becom-
ing evident. It was postulated in the
1930's, and it is now clearly estab-
lished, that the atmospheric COn con-
tent is increasing as a result of com-
bustion of fossil fuel. Radiative
transfer calculations indicate that if
the CO- content increases, and noth-
ing else changes, temperature at the
earth's surface will increase. No one
ever seriously suggested that "noth-
ing else changes," but it was noted
that during the first forty years of
this century recorded surface tem-
peratures did increase. The connec-
tion with CO:; increase was noted and
extrapolated. There were prophecies
of deluge following melting of the
polar ice. However, by 1960 it was
clear that surface temperatures were
falling, and at the same time the
continent-wide increase in turbidity
was noted. (A global increase cannot
be established because a network of
suitable observations does not exist.)
The obvious connection, on the hy-
pothesis that solar radiation at the
surface had decreased and nothing
119
PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM
else had changed, was made. The
extrapolators moved in, and there
were prophecies of ice ages.
Statistical and physical explana-
tion of the problem of climatic change
can be conceived, but each approach
has fundamental difficulties. In the
lirst case, existing series of climatic
statistics based on instrumental read-
ings are short — about 250 years is
the longest reliable record. The stat-
istics of these long series are not
stationary; there is variance at the
longest periods they cover. Historical
and geological evidence indicates
greater fluctuations of climate than
the instrumental record. Statistics in-
dicative of climate are not stationary.
There can be no test of significance
to separate climatic change that might
be associated with man's activities
from the "natural" changes associated
perhaps with internal instabilities of
the ocean-atmosphere system or per-
haps with extraterrestrial change.
The physical approach leads to sim-
ilar conclusions, as Lorenz, in par-
ticular, has pointed out. The equa-
tions governing the ocean-atmosphere
system certainly have innumerable
solutions, and it may be that sets of
these solutions exist with very dif-
ferent statistics — i.e., that the earth
may have many possible climates
with its present atmospheric composi-
tion and external forcing function.
At most, changing the composition
of the atmosphere (e.g., by adding
CO2) might change the nature of
the inevitable change of climate.
Indicated Future Research
Present activity is in two direc-
tions— confirming and extending our
knowledge of the changes of atmos-
pheric composition due to industrial
activity by monitoring programs,
and developing physical models of
the climate. This latter is one of the
major scientific problems of the age,
and we do not yet know whether it
can be resolved to any useful extent.
The requirement is for a model, sim-
ilar to existing models of the global
atmosphere and ocean but completely
independent of any feature of the
present climate. The most complex
existing models incorporate a forcing
function specified in terms of the cur-
rent climatological cloud distribution
and ocean surface temperature. The
output of these models can, therefore,
at best only be consistent with the
existing climate. The requirement is
for a model which will generate its
own cloud distribution and ocean-
surface temperatures.
120
PART V
SEVERE STORMS
1. HURRICANES
The Origin of Atlantic Hurricanes
Atlantic hurricanes are uncommon
events by comparison with the fre-
quency of the storms that parade
across the temperate latitudes of the
United States each month. In terms
of their deadly, destructive potential,
however, they are, individually, the
greatest storms on earth and the
most important natural phenomena
to affect the welfare of the United
States. A single event may visit more
than a billion dollars of damage and
result in hundreds of lives lost,
mainly due to drownings. In addition
to carrying sustained winds that
sometimes exceed 150 miles per hour
and hurricane tides that may rise
more than 20 feet above mean sea
level, this massive atmospheric storm
often carries with it families of tor-
nadoes running ahead of the highest
tides and strongest winds. For ex-
ample, in Hurricane Beulah, which
moved into the lower Texas coast
in 1967, a total of 49 verified tor-
nadoes was reported.
The quest for a better understand-
ing of the hurricane, for means of
increasing the accuracy of forecasts,
and, ultimately, for reducing the ex-
tent of hazard has focused attention
on the source regions of the seedling
disturbances from which hurricanes
grow, and on the environmental
structure of the equatorial trough and
the trade winds which control the
forces promoting hurricane develop-
ment. This quest has been greatly
assisted by a new tool of observa-
tion, the meteorological satellite,
which maintains a continuous global
surveillance of cloud groups produced
by disturbances and storm systems.
Surveillance and Prediction of
Hurricane Seedlings
On average, more than 100 hur-
ricane seedlings move westward
across the tropical Atlantic during
the course of a hurricane season,
June through November. These seed-
lings are initially benign rain storms
which move westward in the flow of
the trade winds. Less than one-fourth
of the seedlings develop circulation
eddies with discrete centers of low
pressure, and an average of only 10
per year intensify enough to sustain
gale-force winds and earn a girl's
name as a tropical storm. On aver-
age, 6 of the 10 tropical storms reach
hurricane intensity at some stage in
their lifetime and 2 of these cross
the U.S. coastline.
For many years, meteorologists
have known that some hurricanes
seem to have their origin near the
west coast of Africa. Not until the
meteorological satellite provided daily
information on storm systems around
the globe, however, was it apparent
not only that hurricane seedlings
could be traced back to the African
coastline in many instances, but also
that they seemed to stem from a
source region near the Abyssinian
Plateau of eastern Africa. They
march in great numbers across arid
portions of Africa before reaching the
Atlantic Ocean, where they begin ab-
sorbing the moisture necessary to
drive a vigorous storm system.
A census of the hurricane seedlings
that occurred in 1968 is presented in
Figure V-l, which diagrams the
sources and movement of disturb-
ances and their evolution into tropi-
cal storms. The parade of disturb-
ances, mainly from Africa westward
across the Atlantic and Caribbean,
extends across Central America into
the eastern Pacific. Approximately
three-fourths of the eastern Pacific
storms are spawned by seedlings
whose origin is on the Atlantic side
of Central America.
It is noteworthy, however, that
not all hurricanes form from seed-
lings which had sources in Africa.
Indeed, not all hurricanes form in the
tropics. Almost every year one or
two hurricanes develop from tem-
perate-latitude systems. Typically, the
trailing edge of an old worn-out cold
front, while losing its temperature
contrast, acquires a rich influx of
moisture from the tropics. The proc-
ess causes a circular storm to form
and to develop the structural char-
acter of the hurricane. Since this
process frequently takes place in close
proximity to a U.S. coastline, it poses
a particularly challenging warning
problem.
Surveillance — The surveillance of
hurricane seedlings and of hybrid
disturbances that may become hurri-
canes is done mainly by satellite
cloud photography. Figure V-2, for
example, shows a series of hurricane
seedlings in the tropical Atlantic and
a hurricane that is lashing the Texas
coast — in this case, Hurricane Beu-
lah, September 18, 1967. Two tropi-
cal storms are also visible in the
eastern Pacific Ocean. In such photo-
graphs, the satellite looks down es-
sentially on the exhaust product of
the heat engine that generates the
clouds.
At present, inferences about the
efficiency of the engine and the en-
ergy that is being released must be
drawn empirically and indirectly.
However, second-generation satellites,
and techniques for analyzing the
movement of cloud segments from
successive pictures, will soon provide
more direct means of assessing the
changes in horsepower that the heat
engine develops.
The tracking and prediction of hur-
ricanes cannot be done with meteoro-
123
PART V — SEVERE STORMS
Figure V-1 — A HISTORY OF HURRICANE SEEDLINGS
The diagram shows areas of formation and decay of hurricane seedlings during
1968. Although the African continent appears to be important in the development
of seedlings, some form in other parts of the Atlantic and the Caribbean. A hurri-
cane may develop from any of the seedlings. Surveillance and tracking is much
easier with satellites, but the question of why one seedling develops into a hurri-
cane and another does not remains unanswered.
TROPICAL
STORMS
Figure V-2 — HURRICANE BEULAH, 1967
BEULAH
SEEDLINGS
This cloud mosaic from September 18, 1967, shows Hurricane Beulah before it
struck the Texas coast. The mosaic was compiled from pictures taken on eleven
successive passes by the polar orbiting satellite, ESSA-3. Polar orbiting satellites
pass over a given area twice per day, once during daylight hours and once at night.
logical satellites alone. Judicious de-
ployment of aircraft reconnaissance
is also required to probe the storm
center directly. The delicate balance
of forces that usually exists within
a hurricane and determines its destiny
can be measured only by direct sens-
ing, and the only practicable tool in
sight for this purpose is the recon-
naissance aircraft.
Numerical Modeling — The prob-
lem of modeling numerically the
movement and development of hur-
ricane seedlings, and especially the
movement of full-blown hurricanes,
is more complicated than that of
modeling temperate-latitude frontal
storms. The large-scale temperate-
latitude storm derives its energy
mainly from the sinking of large
amounts of cold air, a process that
can be described in terms of tem-
perature contrasts on a scale of many
hundreds of miles. The tropical
storm, in contrast, develops in an
environment where lateral tempera-
ture constrasts are absent.
124
HURRICANES
The release of energy in a devel-
oping tropical storm involves a num-
ber of links in a chain of actions,
each of which must unfold in a timely
and effective manner if the storm is
to develop. First, the environment
must be structured to support the
spin that tries to develop locally in
the wind circulation when pressure
first begins to fall. Second, the en-
vironmental winds must be able to
distribute systematically the heat re-
leased by the large cumulus clouds
that spring up near the area of max-
imum spin. It is the systematic dis-
tribution of this heat, not its release
per se, which generates fresh kinetic
energy for intensification of the storm
system.
As the tropical storm intensifies
further and approaches hurricane
force, the system depends uniquely
on a continuous flow of heat energy
from the sea to the air. These proc-
esses involve a subtle interaction be-
tween the scales of motion charac-
teristic of temperate-latitude storms
and those characteristic of cumulus
clouds only a few miles in diameter.
This interaction is difficult to model,
as is the flow of heat energy from the
sea to the air. The primary purpose
of project BOMEX (Barbados Ocean-
ographic and Meteorological Experi-
ment) conducted from May through
July of 1969, was to gain better
understanding of the exchange proc-
esses across the ocean/atmosphere
interface.
The modeling problem, especially
in connection with the tracking of
undeveloped disturbances, is further
complicated by the fact that in the
tropics there is essentially a two-
layer atmosphere, with disturbances
in the lower layer sometimes travel-
ing in a direction opposite to those
in the upper layer.
Because of all these complications,
no model yet exists that can predict
in real-time the moment and develop-
ment of hurricane seedlings. A num-
ber of diagnostic models have been
produced which seem to simulate, in
a research environment, many of the
physical processes that occur during
this development and that charac-
terize the behavior of the full-grown
hurricane. However, forecasting pro-
cedures for tropical disturbances and
storm systems still depend primarily
on the identification, description,
tracking, and extrapolation of the
observed movement of the system.
Present-Day Techniques — Fortu-
nately, the digital computer provides
the forecaster with rapid data-
processing which enables him to as-
sess the immediate behavior of storm
systems and how this may reflect
on the future movement and devel-
opment potential. Because of the in-
creasing use of machines for data-
processing, it is now possible to make
more extensive use of analogues to
compare the present storm system
with similar systems from historical
records and thereby compute the
probable movement and intensifica-
tion to be expected.
Figure V-3 is an example of one
such method developed during 1969
at the National Hurricane Center.
In this case, the computer is required
to search historical records for all
storms that were similarly located
and whose characteristics were com-
parable to the storm system for which
a forecast must be made. From the
historical record, a most-probable
track for periods up to 72 hours is
determined and a family of prob-
ability ellipses is computed show-
ing expected deviations from the
most-probable track (50% and 25%
probability areas). This family of
ellipses is used to identify the area
of the coastline to be alerted initially
to the threat of a hurricane.
Other more sophisticated tools, us-
ing statistical screening techniques,
are also used by the forecaster to
guide his judgment in predicting hur-
ricane movement.
105W
Figure V-3 — PROBABILITY FORECASTS FOR HURRICANES
100W 95W 90W 85W 80W 75W
70W
35 N
30N
25 N
20N
In this relatively crude warning technique, a computer searches historical data to
find a hurricane situation with similar characteristics to the one under observation.
It then prognosticates future positions for 12, 24, 36, 48, and 72 hours, as shown
in the figure, based on the history of the earlier hurricane. The size of the proba-
bility ellipses indicates the magnitude of error that is involved in the use of this
technique.
125
PART V — SEVERE STORMS
Development of still more sophis-
ticated prediction models depends on
a better means of observing the in-
teractions between large and small
scales of motion. The major emphasis
of the Global Atmospheric Research
Program's first tropical experiment,
scheduled for the Atlantic Ocean in
1974, will be to describe and under-
stand cloud clusters. The results of
this investigation should provide
valuable guidance in modeling the
interaction between meso- and syn-
optic-scale motions. For the imme-
diate future, however, the emphasis
will probably have to remain on
development of numerical methods
that will minimize errors in predict-
ing tropical disturbances and storms.
Unless vast resources are devoted to
the problem, sophisticated prediction
models are not apt to become avail-
able in less than five to eight years,
if then.
The median error in predicting the
landfall of hurricanes along a U.S.
coastline continues to decrease slowly,
although it varies from year to year.
This progress is due not so much to
advances in modeling hurricanes
numerically as it is to the availability
of better facilities to track and ob-
serve disturbances at each stage of
development and of modern tech-
nology that provides rapid processing
of data from the storm area and
environment. These facilities permit
us to apply diagnostic tools of rea-
soning in an objective fashion, though
we have only scratched the surface
in the development of such tools.
Apart from any progress that might
be made in modeling the behavior of
hurricanes, there is good reason to
estimate that the median error for
predicting hurricane movement near
our coastlines, now about 110 nauti-
cal miles for a 24-hour movement,
can be reduced by 30 to 40 percent.
This depends, however, on exploiting
information from the meteorological
satellite to obtain numbers — rather
than impressions — concerning the
physical character of the environment
in which the hurricane or its seedling
moves.
Basic Understanding of the
Hurricane System
While much has been learned
about the hurricane, its structure,
and the energetics that cause a seed-
ling disturbance to develop, there
remain notable gaps in the funda-
mental understanding of the hurri-
cane system. The first is the puzzle
of why so few hurricanes manage
to develop from the abundance of
seedlings that parade across the tropi-
cal scene. Secondly, the hurricane is
basically an unstable system varying
in intensity from day to day and
even from one six-hour period to the
next, but the reasons for these varia-
tions are not understood. The whole
concept of weather modification in
hurricanes may depend on a better
understanding of the natural instabil-
ities in this delicately balanced sys-
tem.
Answers to these questions will
probably depend on a concerted pro-
gram of field experimentation and
numerical modeling. To pursue the
problem only through numerical
modeling is risky for the simple
reason that, in so complex a system,
the modeling problem becomes in-
tractable unless there are extensive
uses of approximations, parameteri-
zations, and other mathematical sim-
plifications which, while yielding in-
teresting results, may only crudely
simulate the real atmosphere. Ex-
perience has shown that the best
results come from a two-pronged
program which, in step-wise fashion,
produces a model for one facet of
a development and then verifies the
result of this simulation by field
exploration in the real atmosphere.
Prospects for Reducing the
Hurricane Hazard
Ideally, one would like to find some
means to prevent all hurricane seed-
lings from developing into severe
storms while retaining the useful
rainfall carried by these disturbances.
Although many suggestions have
been made for cloud-seeding or other
cloud-modifying measures to curb
the formation of hurricanes, none has
comprised a physical hypothesis that
has considered both the cloud proc-
esses and the circulating properties
of the cloud environment.
It appears more and more likely
that the formation of a hurricane is
something of an accident of nature,
at least with regard to the particular
cluster of clouds in which the event
occurs. In general, a storm center
tends to form somewhere in an en-
velope of rain clouds spread over
hundreds of miles. But there is still
no reliable means of predicting which
particular cluster nature will pick to
foster the growth of a storm center.
Therefore, even if one knew precisely
what modification techniques to ap-
ply to a cluster of clouds (no more
than 25 or 30 miles in diameter, for
example) — and one does not know
this yet — it would be impossible to
know where to send the aircraft to
conduct the seeding or take other
preventive actions.
Cloud Seeding: Project STORM-
FURY — As for curbing the fury of
the hurricane, it must be conceded
that, at present, the only hope lies
in identifying, and hopefully treading
on, the "Achilles heel" of a delicately
balanced storm system — its ability
to release latent heat under certain
circumstances. That is precisely what
the Project STORMFURY hypothesis
seeks to accomplish.
While scientists do not yet fully
agree on the benefits to be expected
from systematically seeding hurri-
canes or seeking in other ways to
upset the balance of forces in the
storm, those who have followed the
STORMFURY experiments cannot
help but be excited about the very
encouraging results obtained in 1969
from Hurricane Debbie. If the same
order of response from cloud seeding
is obtained in one or two additional
experiments, it will be possible to
demonstrate beyond a reasonable
126
doubt that a significant reduction
can be made in the destructive po-
tential of hurricanes, including the
damage due to hurricane tides, by
strategic seeding of the eye wall.
This is the most exciting prospect in
all geophysical research and develop-
ment, both because of the immediate
potentialities for reducing property
losses and saving lives in hurricanes
and because the insight gained from
this experiment should open the door
to more far-reaching experiments
aimed at modifying other threatening
large-scale storms.
A Report on Project STORMFURY:
Problems in the Modification of Hurricanes
Damage to property in the United
States caused by hurricanes has been
increasing steadily during this cen-
tury. Hurricanes caused an average
annual damage in the United States
of $13 million between 1915 and
1924. By the period 1960 to 1969,
this figure had soared to $432 million.
Hurricane Betsy (1965) and Hurri-
cane Camille (1969) each caused more
than $1.4 billion in damage. Even
after adjusting these values for the
inflated cost of construction in recent
years, there remains a 650 percent
increase in the average annual cost
of hurricane damage in less than 50
years. Since Americans are accelerat-
ing construction of valuable buildings
in areas exposed to hurricanes, these
damage costs will probably continue
to increase.
The loss of life from hurricanes
has been decreasing about as dra-
matically as the damages have been
increasing. This decrease in number
of deaths can be attributed largely
to improvements in hurricane warn-
ing services and community prepared-
ness programs. The reduction in loss
of life is especially notable consider-
ing that the population has been in-
creasing in hurricane-vulnerable areas
just as rapidly as the value of prop-
erty. Figure V-4 illustrates the trends
with time in damages and loss of
life in the United States caused by
hurricanes.
When warnings are timely and
accurate, lives can be saved by evacu-
ating people to safe locations. Prop-
erty damages can be reduced only
by building hurricane-resistant struc-
tures or by reducing the destructive
potential of hurricanes. But the first
solution may be quite expensive.
Extreme destruction may result
from any one of three different at-
tributes of a hurricane: (a) the storm
surge, associated ocean currents, and
wave action along the coast; (b) the
destructive wind; and (c) rain-created
floods. The hurricane winds that
Figure V-4 — HURRICANE LOSSES BY YEARS
Millions of Dollars
16001
1400
1200
1000
800
600
400
200
DAMAGE
ADJUSTED TO
1957-59 BASE
DEATHS
Number of Deaths
4000
- 3500
Hhn
3000
- 2500
2000
1500
1000
500
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The bar graph shows the trends in loss of life and damage due to hurricanes. The
damage figures have been adjusted to eliminate inflationary and other fluctuating
trends in the cost of construction.
127
PART V — SEVERE STORMS
sometimes approach 200 miles per
hour may cause storm surges of 20
to 30 feet or so, the development of
strong coastal currents which erode
the beaches, and the onset of moun-
tainous waves. Once the latter three
elements are in being, they are far
more destructive than the winds and
are usually responsible for the greater
damage. Their destructive power
varies directly with the speed of the
winds.
Damage due to sea forces and to
winds is concentrated along and near
the seacoast; even the damage at-
tributed to winds alone usually drops
off drastically within a relatively few
miles of the coast when a hurricane
moves inland. Damage from rain-
caused floods, on the other hand, may
extend far into the interior and is
particularly acute in mountainous
regions traversed by the remnants of
a hurricane. This is especially true
in situations where rain-induced
floods originate in mountains near
the coast and arrive at the coastal
plain before the ocean waters have
receded. In view of the difficulty of
building structures to resist all these
destructive elements, efforts have
lately concentrated on reducing the
destructibility potential of hurricanes.
If the present program for modi-
fying hurricanes to reduce their in-
tensity should prove effective, the
potential benefit/cost ratio could be
of the order of 100:1 or 1,000:1. It
should be emphasized that the modifi-
cation program has no intention of
either "steering" or completely de-
stroying hurricanes. The rainfall
from hurricanes and tropical storms
is an essential part of the water bud-
get of many tropical and subtropical
land areas, including the southeastern
United States. The hope is to reduce
a hurricane to a tropical storm by a
reduction in the speed of the concen-
trated ring of violent winds near the
center, leaving the rainfall and total
energy release of the over-all storm
essentially unchanged.
Details of the Project
The groups active in Project
STORMFURY, a joint effort of the
U.S. Navy and the National Oceanic
and Atmospheric Agency (NOAA),
conducted experiments on hurricanes
in 1961, 1963, and 1969. In each
case, the objective was to reduce
the maximum winds of the hurricane.
The technique called for seeding a
hurricane with silver iodide crystals
in order to cause supercooled water
drops to freeze and release their latent
heat of fusion. In the earlier years,
the experiments consisted of seeding
a hurricane one time on each of two
days. The results appeared favorable
but were inconclusive, since the
changes were of a magnitude that
often occurs naturally in hurricanes.
In August 1«60, the STORMFURY
group seeded Hurricane Debbie five
times in a period of eight hours on
the 18th and 20th of the month, with
no experiment on the 19th. Following
the seedings, maximum winds at
12,000 feet decreased within six
hours by 31 percent on the 18th and
15 percent on the 20th. The storm
regained its original intensity on the
19th. While changes of this mag-
nitude have happened in hurricanes
on which there was no experiment,
they have been quite rare. When one
considers the entire sequence of
events in 18-20 August, one can say
that such a series of events has not
happened in previous hurricanes
more than one time in 40. Thus,
while we cannot state that the Debbie
experiments proved that we know
how to modify hurricanes, the results
were certainly very encouraging.
Along with the experimental pro-
gram, there has been an intensive
effort to develop models which simu-
late hurricanes. The best of these
models now reproduce many features
of a hurricane quite well. One devel-
oped by Rosenthal has been used to
simulate seeding experiments, includ-
ing the one performed on Debbie.
The STORMFURY experiment was
simulated by adding heat at appro-
priate radii at the 500 and 300 milli-
bar levels (approximately 19,000 and
32,000 feet, respectively) over a pe-
riod of ten hours. The amount of
heat added was believed to be com-
parable to the amount of latent heat
that can be released by seeding a
hurricane. Within six hours after
cessation of the simulated seeding,
the maximum winds at sea level
decreased about 15 percent. The
time-scale for the decrease in max-
imum winds was roughly the same
as that in the Debbie experiments.
Evaluation of Results
The net results of the various field
experiments and the implications
from modeling experiments give
strong reason for believing that at
least some degree of benefical modifi-
cation was achieved in the Debbie
experiments. Unfortunately, how-
ever, we cannot say the matter is
proved nor can we claim the results
are statistically impressive at some
high level of significance.
The modeling results are most in-
teresting and highly suggestive, but
there are certain deficiencies in the
model which require that one be
cautious in interpreting them. First,
a highly pragmatic parameterization
of cumulus convection is used. Sub-
stantial improvements in this area
must await increased understanding
of both cumulus convection and its
interaction with larger scales of mo-
tion. Second, the major simplifying
assumption of circular symmetry
used in the model precludes direct
comparison between model calcula-
tions and specific real tropical cy-
clones. Real cyclones are strongly
influenced by interaction with neigh-
boring synoptic systems, and these
vary markedly in character and in-
tensity from day to day.
When one looks at parameters
other than the winds for further
verification of seeding effect, either
the data were not collected in Hur-
ricane Debbie or insufficient data are
128
HURRICANES
available from previous storms to
provide a clear definition of the nat-
ural variability of the parameter.
These points can be illustrated by
discussing the various measurements
that should be made.
The following are either assumed
by the modification hypothesis or are
implied by results from the modeling
experiments:
1. In hurricane clouds, large quan-
tities of water substance exist
in the liquid state at tempera-
tures lower than —4° centi-
grade.
2. Introduction of silver iodide
crystals into these supercooled
clouds will cause the water
droplets to freeze and release
the latent heat of fusion.
3. If the heat is released in the
annulus radially outward from
the mass of relatively warm air
in the center of the storm, it
should cause a temperature
change that will cause a reduc-
tion in the maximum tempera-
ture gradients in the hurricane.
4. A reduction in the mean tem-
perature gradients must result
hydrostatically in a reduction
of the maximum pressure gradi-
ent in the storm.
5. A reduction in the pressure
gradients should cause a reduc-
tion in the maximum winds in
the storm.
6. The belt of maximum winds
should migrate outward after
the seeding has had time to
affect the storm. This action
presumably would be accom-
panied by development of a
larger eye, with the eye wall at
a larger radius, or, possibly, a
change in structure of the wall
cloud.
All of the above suggest certain
measurements that should be made
in the storm. If the changes in these
parameters occur at the right time, in
the right sequence, and with proper
magnitudes, the cumulative evidence
that the experiment was a success
could be very convincing. Efforts
were made to collect all of these data
in Debbie. In some cases, however,
the efforts were unsuccessful or the
data do not permit conclusive deduc-
tions.
An aircraft was equipped to make
measurements of the character and
amount of water substance in the
lower levels of the supercooled layer
in Hurricane Debbie. While attempt-
ing to make the first pass across the
storm at the 20,000-foot level, a
supercharger malfunctioned and the
aircraft was no longer able to main-
tain that high an altitude. There are,
however, some qualitative observa-
tions which suggest there was a
change in character of the water
substance from predominantly super-
cooled water to a mixture of ice and
water. These observations are not
at the right level or of sufficient
detail and quality to document incon-
trovertibly that the seeding accom-
plished a major transformation in the
liquid-ice budget of the clouds. This
should not be interpreted to mean
that the seeding failed to accomplish
the desired effect, however. There
are just insufficient data to convince
a skeptic that the effect was actually
achieved.
Very detailed and frequent obser-
vations of the temperature, pressure,
and winds were made along diameters
across the hurricane at the 12,000-
foot level. From these data we can
compute changes with time in the
parameters of their gradients at any
point along the diameter. The changes
in the maximum wind speed have
already been mentioned.
The changes observed in tempera-
tures and temperature gradients are
not conclusive enough to support the
above hypotheses. On the other
hand, if the release of latent heat
was in the layers above 18,000 feet,
one should not expect dramatic
changes in the temperature and its
gradient at 12,000 feet. We have in-
adequate temperature measurements
in the layer between 18,000 feet and
30,000 feet, since lack of properly
instrumented aircraft precluded the
acquisition of the type and quantity
of data needed. Furthermore, results
from the seeding simulation experi-
ment conducted with the model sug-
gested that the added heat is rapidly
dispersed and dramatic changes in
the temperatures are not likely to
occur.
The changes in the pressure and
pressure gradients measured at 12,000
feet do give some support to the
success of the seeding and some indi-
cation that results conformed to the
hypothesis. But the great amount of
noise in the variations of this param-
eter and lack of adequate knowledge
concerning natural variations in hur-
ricanes make it impossible to say the
case is proved. Once again, the in-
dications are positive but inconclu-
sive.
Intensive efforts were made to get
continuous coverage of the structure
of the storm by airborne radar and
by the ATS-3 satellite. This was
done with the hope that these data
would reveal the nature and time
of changes in the cloud structure
that might be caused by the seeding.
The radar pictures suggest that the
eye size did become larger after the
seedings; the changes in size even
appeared to have a periodicity sim-
ilar to that of the seedings: about an
hour and a quarter after several of
the seedings there was a rapid in-
crease in the area encompassed by
the wall cloud.
One must be cautious, however, in
placing too much emphasis on this
evidence. The eye wall was pulsating
during most of the time the STORM-
FURY crews were monitoring it, so
there were many changes in size,
shape, and character of the eye be-
fore, during, and after the seeding.
There were also many problems with
129
PART V — SEVERE STORMS
the data. No single radar monitored
the storm during the entire seeding
operation, and it was necessary to
use various radars to obtain a con-
tinuous time record of the eye area.
After considering the many prob-
lems of interrelating various radars,
calibrating ranges, distortions, etc.,
one can only conclude that there is
some evidence that the seeding did
indeed affect the hurricane clouds
around the eye in the manner hy-
pothesized, but that the data are
of such a heterogeneous nature as to
be inconclusive in themselves.
Pictures of Hurricane Debbie were
taken by ATS-3 each day of the
period, 17-21 August. Normally,
processed pictures do not reveal
much detail of the seeded areas.
Although enhanced pictures were
made along lines suggested by Fujita,
they have not yet been developed.
Work with a small sample of these
pictures suggests that we will obtain
some interesting information about
changes in the cloud structure of
the storm, though it is unlikely that
these pictures will be adequate for
determining with confidence whether
the seeding had a major effect on the
changes.
Wind-field measurements did show
that the radius of maximum winds
increased following the seeding.
Requirements for Future Activity
The use of theoretical models to
study the modification hypotheses
was discussed in the previous section.
Some deficiencies of the present mod-
els were also mentioned. We should
use the present models to learn as
much as possible about the interac-
tions and potential instabilities of
hurricanes, but we should also con-
tinue experiments to develop further
information as to how well the mod-
els simulate actual hurricanes. At
best, they can do this only in a mean
sense. We should also continue work
to remove the restrictive assumptions;
these relate to circular symmetry,
interaction between the hurricane
and synoptic-scale features in the
environment, dynamics of cumulus
clouds, and interactions between the
hurricane scale of motion and circu-
lations of smaller scale. The matter
of parameterizing cumulus processes
in the model must be re-examined
and carefully compared with cumulus
models and observations. A more
closely spaced grid should be used
in the eye-wall region. And, finally,
the outer radial boundary (now at
440 km) should be moved outward
and other outer boundary conditions
investigated to make sure they are
not determining or markedly affect-
ing the solutions following the "seed-
ing."
When the field experiments are
repeated, every effort should be made
to obtain data that will permit veri-
fying various steps related to the
seeding hypotheses. These were dis-
cussed in the preceding section. Fa-
cilities and manpower are not avail-
able at the present time to obtain all
of these data.
In summary, the present status of
our scientific knowledge suggests
quite strongly that techniques pres-
ently available are adequate to
achieve beneficial modification of
mature hurricanes. Data from experi-
ments and theoretical studies support
each other, but in each case there
are gaps in our knowledge which
suggest we should be cautious in
making extreme claims. What is clear
is that we should repeat the Debbie-
type experiments on other hurricanes
as soon as possible to see if we can
duplicate the Debbie decrease in wind
speeds and to document details of
the effects. We should continue our
theoretical investigations to remove
some of the limiting assumptions.
With losses from hurricanes in the
United States currently averaging
over $400 million per year and loss
of life still a threat, action should
be taken as soon as possible. Since
the prospects seem good that we can
reduce the destructive power of hur-
ricanes, the need for additional ex-
periments becomes much more ur-
gent.
If present techniques are adequate
for modifying a hurricane, it is quite
likely that we can collect enough
information during the next one or
two years to justify application of
the experiments to storms expected
to affect the coastline. If present
techniques are inadequate, we have
several other approaches which should
be explored. The time needed to
develop and test better hypotheses
or to improve and exploit the present
hypotheses suggests that we should
plan five to ten years ahead.
The Scientific Basis of Project STORMFURY
Project STORMFURY is concerned
with the problem of devising ex-
periments to modify hurricanes and
tropical cyclones. Because the design
and evaluation of such experiments
depends essentially on understanding
the structure and behavior of "nat-
ural" hurricanes, the close associa-
tion of the project with the National
Hurricane Research Laboratory of the
National Oceanic and Atmospheric
Administration is appropriate. The
impetus for such experiments arises
primarily from the large potential
benefits, in the form of reduced prop-
erty damage and loss of life, which
could be realized from relatively small
modifications of the intensity or mo-
tion of these storms.
During the past decade, increased
understanding of hurricanes, based
on both descriptive and theoretical
studies, has suggested at least two
130
HURRICANES
possible avenues of achieving benefi-
cial modification. Utilization of the
approach with the sounder basis of
scientific understanding has so far
been precluded by logistic considera-
tions. The second approach, which
involves complex but feasible logis-
tics, has been used in experiments
on three hurricanes with encouraging
but not yet definitive results even
though the detailed physical basis
for the approach is not completely
understood.
Present Scientific Status
Special observational efforts and
more intensive theoretical studies
during the past twenty years have
led to important advances in the
understanding of the physics of hur-
ricanes, but significant gaps remain
to be filled. Preliminary efforts at
constructing mathematical models of
the hurricane have been encouraging,
but serious defects remain.
Data Base — For hurricanes in the
mature stage and in dissipating stages
over land, the descriptive data base
is good in the qualitative sense. The
principal data deficiencies consist of
quantitative measurements of such
items as: the distribution of water
in all phases as a function of tem-
perature in the storm; the fluxes of
heat and water vapor from the sea
to the air under the extreme condi-
tions present in the hurricane; and
the natural variability of various
meteorological parameters in the
inner regions of the hurricane as a
function of time-scales ranging from
an hour to a day or two.
Basis for Modification — The most
significant addition to our scientific
knowledge of hurricanes in recent
years has been the convergence of
both theoreticians and empiricists on
the concept that the hurricane is the
complex result of the interaction of
physical processes on several dis-
tinctly different scales. It is now
agreed that these storms, whose
space-scale of a few hundred kilo-
meters and lifetime of a few days
typify the synoptic-scale of atmo-
spheric systems, depend critically on
microscale (1 to 10 meters) turbulent
motions of the surface boundary
layer for the addition of heat and
water vapor from the sea surface, and
on mesoscale convective clouds, pri-
marily organized in the annular ring
surrounding the eye, for release of
the latent heat of water vapor as the
primary driving mechanism of the
storm. Furthermore, the combined
processes on these scales are influ-
enced by interactions with much
larger scale systems of the atmos-
phere.
It is this dependence on microscale
turbulence and mesoscale convection
that has suggested the two avenues
to modification. Reduction of the
evaporation associated with the for-
mer would certainly result in reduc-
tion of hurricane intensity, but this
approach to modification has been
prevented by insurmountable logistic
problems. Redistribution of the
latent heat release associated with
the latter through the use of cloud-
seeding techniques shown to influ-
ence the structure and dynamics of
convective clouds is logistically feas-
ible and has been employed in ex-
periments on a small number of
hurricanes. There are residual un-
certainties and disagreements as to
the correct seeding techniques and
the interpretation of the experimental
results.
Theoretical models of the hurricane
incorporating the various scales dis-
cussed above with varying degrees
of simplification have been developed.
Results of computer simulations
based on these models indicate qual-
itative success in modeling the physi-
cal processes responsible for the
formation and maintenance of the
hurricane. But significant quantita-
tive uncertainties remain. Further-
more, present models cannot con-
tribute significantly to problems of
hurricane motions.
Interactions — Our present scien-
tific knowledge and understanding
of the interaction of hi
other aspects of the atmospheric gen-
eral circulation, with other environ-
mental systems such as the ocean,
and with man and society are qualita-
tive and inadequate. For example,
it is known that rainfall associated
with hurricanes is often of consider-
able economic benefit, but it can also
lead to disastrous floods. We do not
know how the atmospheric circula-
tion would change if hurricanes did
not exist. Nor is it decided who in
society is to decide when and where
hurricane modification should be at-
tempted.
Requirements for Scientific
Activity
Significant scientific controversy
exists with respect to the following
aspects of hurricane modification:
1. Can the effects of seeding ex-
periments be unequivocally de-
tected against the large natural
variability of hurricanes?
2. How, exactly, does cloud seed-
ing redistribute latent heat re-
lease and how is this redistribu-
tion responsible for decreases
in hurricane intensity?
3. Are the present mathematical
models and associated com-
puter simulations of hurricanes
sufficiently realistic to serve as
indicators of differences in ex-
pected behavior of natural and
seeded hurricanes?
4. Are the amounts of super-
cooled liquid water necessary
if seeding techniques are to
result in significant redistribu-
tion of latent heat release ac-
tually present in the correct
portions of the storm, and is
this water actually frozen by
the seeding?
The most urgently needed scien-
tific advances fall into two categories:
observations and theoretical model-
131
PART V — SEVERE STORMS
ing. Observations are needed to
document more thoroughly the nat-
ural variability of hurricanes; to de-
termine the distribution of water in
all its phases in the inner portions of
both natural storms and before, dur-
ing, and after seeding in experimental
storms; and to quantify further the
interactions among physical processes
on the various scales important to
hurricanes. Theoretical models and
associated computer simulations need:
(a) to be improved in the way in
which smaller-scale processes are
treated implicitly through parameter-
ized relationships; (b) to be gen-
eralized such that the effects of in-
ternal processes on the motion of
the storm can be treated; and (c) to
utilize improved observations as
varying boundary and initial condi-
tions for the models.
Time-Scale — The urgency of sat-
isfying these needs is undoubtedly
relative. In terms of clarifying the
scientific basis for Project STORM-
FURY, the need is very urgent. To
substantiate the encouraging, but
inconclusive, results from past ex-
perience and, thereby, provide a solid
foundation for modification experi-
ments on storms threatening inhab-
ited coastlines, their importance can-
not be overemphasized.
These advances in scientific back-
ground are needed within one to two
years. Instrumentation and observa-
tional platforms needed to fill most
of the known gaps in the scientific
data base for both natural and experi-
mental hurricanes are available. Sim-
ilarly, significant improvement in
computer simulation is possible with
existing computers.
Legal Implications — The greatest
potential policy problems associated
with hurricane modification will arise
from the legal questions that will be
raised at both national and interna-
tional levels when modification ex-
periments are carried out on storms
which shortly thereafter affect in-
habited coastal regions or islands.
When and if we are able to predict
what will result from such modifica-
tion attempts, who will make the
decisions? A study of these problems
is sorely needed.
A Note on the Importance of Hurricanes
Necessity
Our understanding of the physical
laws governing the behavior of the
atmosphere has not advanced to the
point where we can deduce from
these laws that hurricanes, or any
tropical circulation systems resem-
bling hurricanes, must occur. It is
just reaching the stage where we can
deduce theoretically that systems of
this sort may occur. Recent numeri-
cal experiments aimed at simulating
hurricanes have produced cyclonic
circulations of hurricane intensity
from initial conditions containing
weak vortices. Other experiments
aimed at simulating the global circu-
lation have produced concentrated
low-pressure centers within the trop-
ics, but the horizontal resolution
has been so coarse that it is impos-
sible to say whether the models are
trying to simulate hurricanes.
Nevertheless, from our general
knowledge of atmospheric dynamics
together with the observation that
hurricanes do occur and continue to
occur year after year, we can safely
conclude that hurricanes not only
may but must occur if nature is left
to its own devices. We could make
a similar statement about other at-
mospheric motion systems (e.g., tor-
nadoes) that occur repeatedly.
Such reasoning does not apply to
everything that is observed in nature.
It would be incorrect to conclude,
for example, that a particular species
of animal is necessary simply because
it exists. If we should destroy all
members of the species, there is no
assurance that evolutionary processes
would ultimately create the same
species again. However, hurricanes
are not a species; new hurricanes are
not ordinarily born of old ones. On
the contrary, they, or the weaker
tropical disturbances that mark their
origin, appear to be spontaneously
generated when the proper distribu-
tions of atmospheric temperature,
moisture, wind, oceanic temperature,
and probably certain other quantities
occur in the tropics on a worldwide
or ocean-wide scale.
Strictly speaking, therefore, we
should modify the statement that
hurricanes are necessary by saying
that they are necessary only if the
larger-scale conditions characterizing
the tropical environment are main-
tained over the years. The absence
of hurricanes in the southern Atlantic
Ocean is presumably due to the
local absence of favorable large-scale
conditions, as is the relative scarcity
of hurricanes in other oceans during
the winter season.
What If Hurricanes Could Be De-
stroyed?— Assuming that the tropi-
cal environment is favorable to the
formation of hurricanes, the latter,
in forming, will exert their own ef-
fects on the environment. Hurricanes,
by virtue of the active cumulonimbus
clouds that they contain, are effective
in transporting large amounts of heat
and moisture upward to high levels.
They may also carry significant
amounts of heat, moisture, and mo-
mentum from one latitude to another.
In any event, they act to alter the
environment; in the long run, their
effect on the environment must be
exactly canceled by that of other
processes.
Suppose, then, that nature is not
allowed to take its course. Suppose
132
HURRICANES
that we possessed the means, not for
directly altering the large-scale con-
ditions that favor the development of
hurricanes, but for destroying each
hurricane individually during its
formative stages, soon after its initial
detection. In the hurricane-free world
that we would have temporarily cre-
ated, the effects of hurricanes on the
environment would no longer cancel
the other effects and the environment
would proceed toward a different
state of long-term statistical equi-
librium.
Very likely, the new environment
would be more favorable for the
natural development of hurricanes
than the old one. This would be true
if one of the natural effects of hurri-
canes is to remove from the environ-
ment some of its hurricane-producing
potential, as would be expected if
the hurricane is an instability phe-
nomenon. Perhaps a super-hurricane
would then try to form to do the
work of the ordinary ones that were
suppressed; perhaps it would not.
In any event, the task of artificially
removing the hurricanes one by one,
if such a task can be visualized at all,
would become even more difficult
than it had originally been.
Beneficial Effects
The most frequently cited bene-
ficial effect of hurricanes is probably
the rainfall that they supply to certain
areas, with its obvious value to agri-
culture. A familiar example of such
an area is the southeastern United
States, where a fair fraction of the
total annual rainfall is supplied by
tropical storms. Yet even if this
region were deprived of all its hur-
ricanes, there would still be ample
rainfall left to support other crops
not presently raised in this region.
This leads us to suggest that the
principal beneficial effect of hurri-
canes may be to help preserve the
climatic status quo — a status quo
which the hurricanes themselves have
helped to create.
To appreciate the value of preserv-
ing the status quo, let us suppose that
two regions of the United States, each
possessing a reasonably satisfactory
climate, could somehow suddenly ex-
change climates with one another.
The climatic statistics of the United
States as a whole would then be
unaltered. Yet the average climate of
the United States would be worse,
because the climate would be "worse"
in each of the two regions in question.
That is, the new temperature and
rainfall regime in each region would
presumably be unfavorable to the
plant and animal life existing there,
especially to the crops, and very
likely also to many aspects of human
culture. The new climates would
favor new flora and fauna, and after
a sufficient number of years those
in one region might become effec-
tively interchanged with those in
the other. But during the period of
adjustment there would be a net loss.
Since hurricanes exert a modifying
influence on the larger-scale tropical
environment, a further effect of hurri-
canes is to help preserve the climatic
status quo throughout the tropics,
even in those areas not frequented
by heavy hurricane rains or violent
hurricane winds. Here, too, the effect
may be beneficial.
Geomorphological Effects of Hurricanes
The morphologic changes induced
by hurricanes are concentrated along
seacoasts and the shores of large
estuaries. As they move inland, few
major tropical cyclones encounter at-
mospheric conditions necessary to
maintain their destructive violence
for as much as 100 miles. Only
rarely are they capable of retaining
their structures when crossing land
areas, as from the coast of the Gulf
of Mexico to New England or to the
Canadian border.
Hurricane Camille (1969) — shown
in Figure V-5 — reached the Gulf
Coast as the most intense hurricane
ever reported, breaking records for
barometric depression and wind ve-
locities and bringing tragic devasta-
tion to the coast of Mississippi. It
retained its identity for an exceptional
distance, causing excessive rainfall
and flooding that did considerable
damage in West Virginia and south-
western Virginia the day after leaving
Mississippi. And yet, Camille caused
few morphologic changes of any con-
sequence. It effected many short-
lived, minor physical changes on is-
lands in Louisiana and Mississippi,
but in comparison with losses in hu-
man and animal life and with destruc-
tion of property, the physical changes
were trivial.
Effects of Differing Coastal
Characteristics
Morphologic changes resulting
from hurricanes depend mainly on
the physical characteristics of the
coasts involved. Three examples will
illustrate the relationships:
Plum Island, Massachusetts, expe-
rienced the impact of Hurricane Carol
(1954). A detailed line of levels had
been surveyed across the marshes
behind the island, the coastal dunes,
and the island's beach. This survey
was completed the day before Carol
arrived. On the morning following,
the beach was broadened and reduced
as a result of wave erosion to a level
well below that determined by the
instrumental survey. Three days
later, however, most of the beach
had been restored, and within a few
days following its profile had re-
turned essentially to its pre-hurricane
condition.
133
PART V — SEVERE STORMS
Figure V-5 — HURRICANE CAMILLE, 1969
Hurricane Camille on August 17, 1969, in addition to being very intense, covered an
extremely large area as shown in this segment of a satellite picture from the geo-
stationary satellite ATS 3. A geostationary satellite is fixed relative to the earth
and so is able to photograph the same area once every 25 minutes. Camille was
first observed as a large area of cloudiness over the Lesser Antilles. It was tracked
for over a week before it hit the Mississippi coast with 190-mph winds and 30-foot
tides. Even though adequate warnings were given, many people were killed as a
result of coastal flooding.
Mauritius, during the southern-
hemisphere summer of 1960, felt the
effect of Hurricane Alix, which passed
close to its west coast in January,
and the full impact of Hurricane
Carol in February. Carol was accom-
panied by the lowest barometric de-
pression and most violent winds, as
well as the greatest economic loss,
ever experienced in the southwestern
part of the Indian Ocean. The path
of Carol was such that the 1,200
square mile area of Mauritius was
completely covered by the passing
eye of the storm.
It happened that six months earlier
a field party of the Coastal Studies
Institute of Louisiana State Univer-
sity had completed an intensive study
of the vegetation, landforms, and
beaches of the entire coast. Following
Carol, field parties returned in 1960
and again in 1963 to assess changes.
As a great number of photographs
had been taken during the first visit,
an opportunity was afforded for tak-
ing subsequent photographs from
identical positions with the original
camera. Many individual plants were
re-located, and their conditions were
compared on a basis of pre-hurricane,
a-few-months-later, and three-years-
later investigations. The photographs
and other comparisons demonstrated
very minor physical changes, an im-
mense upset in the exotic flora, and
the rapid recovery of endemic vegeta-
tion.
Louisiana, in June 1957, experi-
enced the direct impact of Hurricane
Audrey, a storm that caused the
greatest loss of life and property
damage of any early-summer hurri-
cane on the Gulf Coast. The coastal
marshes were flooded to almost rec-
ord depths of as much as 13 feet.
The surge of sea water removed
practically all beach sand and shell
for about 100 miles along the coast
of western Louisiana. Loss of this
thin, protective armor exposed readily
eroded marsh sediments to wave ero-
sion, which was responsible for ac-
celerated coastal retreat for as long
as four years, after which effective
beaches accumulated.
In 1953, a field party had been
engaged in the study of a coastal
mudflat that began to form in 1947.
The party had implanted 25 monu-
ments as reference points for that
number of surveyed cross sections.
Most of these survived the onslaught
of Audrey and were used to monitor
coastal retreat at several-month in-
tervals.
The most spectacular geomorphic
event related to the hurricane was
the lifting, shifting, and deposition of
two huge masses of mudflat sediment
during the storm surge. These de-
posits were separated by about 19
miles. The western mass had a max-
imum length of 12,350 feet; the east-
ern deposit, 11,350 feet. The respec-
tive widths were 1,050 and 1,000 feet.
Each overlapped the shore and ex-
tended inland about 2,051 feet, with
an original thickness of 11 inches.
Several months later, after drying,
each mass had formed a sharply
bounded, dense sheet of gelatinous
134
HURRICANES
clay up to 6 inches thick; they are
permanent additions to the marsh
deposits.
Some Generalizations
The three specific examples given
here justify several generalizations
that can be substantiated by many
other case histories:
1. Catastrophic as they are from
human, biological, and eco-
nomic standpoints, in most in-
stances hurricanes result in
only minor and ephemeral geo-
morphic changes, and these are
confined to coasts.
2. A coast where durable rock is
exposed to the violence of
storm attack (Mauritius ex-
ample) suffers negligible physi-
cal change.
3. A coast flanked by deep water
close to the shore (Plum Island
and Mauritius examples) is af-
fected mainly by high seas.
Unconsolidated materials such
as beaches and sand dunes ex-
perience abrupt changes, but
these last for only short periods
of time.
4. A coast flanked by a broad,
gently inclined continental
shelf, with a long fetch across
shallow bottoms, suffers
changes associated with flood-
ing (Louisiana example).
Hurricane Carol (Mauritius)
brought a storm surge that registered
only about 33 inches above expected
level on the tide gauge at Port Louis.
The island is surrounded by deep
water. Hurricane winds generated
high seas along all shores, however,
and it was these that accounted for
physical and biological changes. Much
the same experience was associated
with another Hurricane Carol (Plum
Island). At Plum Island, the 10-
fathom isobath hugs the shore
closely, and a depth of 50 fathoms
lies only 6 miles out. In contrast, in
southern Louisiana the 10-fathom
isobath lies about 43 miles from the
shore, and the 50-fathom depth lies
some 118 miles out. Hurricane surges
are low over open ocean and are not
significant aboard ship, but they rise
to 15 feet or more when their rate of
forward advance is reduced by shear
or friction, creating greater and
greater turbulence and more vigorous
internal waves as they travel across
wide, gently rising bottoms, especially
at shallow depth.
Although not much coastal change
ordinarily occurs when water attains
a depth of more than 5 fathoms
within a short distance, too much de-
pendence should not be attached to
this relationship. With gently in-
clined bottoms, offshore surges may
grow to proportions that create ex-
tensive flooding. These surges con-
tinue for long distances, both across
shallow bottoms and adjacent coastal
lowlands. Even in the extensive and
shallow area east of New Orleans,
local inhabitants identify channels in
the marsh and cuts across linear
islands as having resulted from hur-
ricanes in 1915 and 1925. A popular
resort on Isle Derniere, south of New
Orleans and landward about 27 miles
from the 10-fathom isobath, was
wiped out with tragic consequences
in 1856, when the position of the
low sandy spit on which it was built
was shifted westward.
Hurricane Protection:
Problems and Possibilities
An individual hurricane arrives as
a possibly catastrophic event, one
that is likely to be considered unique
in the minds of people affected. The
fact is, however, that the storm is but
one of a recurring series that reach
the region at highly irregular inter-
vals. Hurricane arrivals are as un-
certain as those of impressive earth-
quakes. Although the present state
of the art does not justify exact fore-
casts concerning either, except for
short terms in the case of hurricanes,
both meteorologists and seismologists
recognize that there are definite hur-
ricane- and earthquake-prone regions.
Eventually, it may be possible to
educate people living in them to
recognize that they must protect
themselves against potential catas-
trophes.
Most hurricanes reaching the
United States originate either be-
tween the Azores and Cape Verde
Islands or else in the Caribbean.
There is no evidence that any origi-
nate within 6" of the equator. In
most cases they are first identified
in latitudes between 10 and 20°
north. The shores of the Gulf and
Atlantic coasts, from Brownsville,
Texas, to Lubec, Maine, are every-
where vulnerable to hurricane attack.
Tracks are particularly concentrated
near Puerto Rico and Florida, but
extreme damage has occurred around
all parts of the Gulf of Mexico and
up the Atlantic seaboard at least as
far as Cape Cod.
Defense against events such as
hurricanes, tornadoes, earthquakes,
and destructive volcanic activity is
most effective in places where dis-
aster strikes most frequently. Cy-
clone cellers have undoubtedly saved
many lives in the American Middle
West. The Japanese have done well
in designing structures that withstand
intense earthquake tremors.
Practically all serious damage re-
sulting from hurricanes is caused by
human mistakes. Protective beaches
are mined for sand, shell, or gravel.
Sand dunes, among nature's most
effective coastal protectors, are bull-
dozed away to level land for building
sites or even to enhance seascape
views. A trip along any part of the
Atlantic coast between Florida and
Cape Cod soon after a hurricane will
demonstrate gross variations in dam-
age, depending on whether beaches
or dunes had been altered seriously.
Cities and towns suffer most, not only
because they are concentrations of
people and buildings but also from
the fact that they have introduced
135
PART V — SEVERE STORMS
many more "improvements" that de-
stroy or upset natural conditions. In-
tervening rural areas are left rela-
tively untouched, particularly if their
coastal sand dunes have been left in-
tact.
It is difficult to convince people
that hurricanes bring most disastrous
results to places near disturbed
beaches and sand dunes, and that
substantial buildings reduce losses of
life immensely. Hurricane Camille
evidenced tremendous contrasts be-
tween the minor damage to substan-
tial buildings and the destruction of
shoddy structures, however nicely
adorned. Great loss of life occurred
in hotels and motels with inadequate
framework, the buildings being held
together mainly by wallboard or in-
sufficiently bonded partitions of thin
concrete blocks. Surges up to twenty
feet high did relatively little damage,
however, to buildings with adequate
frames, whether of wood or steel.
Trailer courts were wiped out, even
several blocks back from the shore,
while old homes with good construc-
tion withstood the surge much better
even where they were located on or
near the Gulf of Mexico.
While the number of seashore
buildings anchored on effective pil-
ings often increases for some years
after a hurricane, this is not always
true. After Hurricane Audrey, nearly
all new houses were built on concrete
slabs at ground level, following the
dictates of a current style rather than
in anticipation that the buildings will
probably be flooded by several feet
of seawater within a decade or two.
People appeared to assume that Au-
drey would be the last hurricane to
strike the coast of southwestern
Louisiana.
The National Weather Service per-
forms an invaluable service in pro-
viding hurricane watches, alerts, and
warnings, each of which becomes
progressively more specific about
time of arrival and width of danger-
ous impact as the storm nears the
mainland coast. But to what extent
has public confidence been created?
For some reason the people in a small
but active community on Breton Is-
land (east of the Mississippi River
Delta) heeded a hurricane warning in
1915. The buildings in the commu-
nity were totally destroyed, and have
not been rebuilt, but every inhabitant
was evacuated before the storm
struck, without the loss of a single
life. In 1957, on the other hand, few
people heeded timely, adequate warn-
ings of the approach of Hurricane
Audrey toward the Louisiana coast.
Many hurricanes had brought storm
surges to the area, but all had been
lower than the elevation of the higher
land in the vicinity (about 10 feet).
Hurricanes were an old story. Most
of the people remained at home and
were totally unprepared for vigorous
surges that swept as much as three
feet across the highest land in the
vicinity, causing tremendous loss of
life and property. On several occa-
sions during the past thirteen years
people have evacuated the region
as soon as early warnings have been
issued, but in no case did a dangerous
surge occur. Will these experiences
result in destroying confidence in
warnings by the time that the next
potential disaster appears?
Awareness of danger is almost im-
possible to maintain for disasters that
recur a generation or more apart.
Probably the most effective hurri-
cane-protection measures result from
legal actions, at state and local levels,
such as the formulation and enforce-
ment of adequate building codes, pro-
vision for rapid evacuation, mainte-
nance of reserve supplies of fresh
water for domestic use, well-con-
structed sanitary systems, and the
availability of carefully planned
health and emergency facilities.
Needed Scientific Activity
In their pristine condition, factors
associated with the destructive effects
of hurricanes are in reasonable equi-
librium with those that resist geo-
morphic change. Scientific knowledge
about hurricane origins, mechanics,
physics, and behavior slowly in-
creases, as does knowledge concern-
ing the destruction or alteration of
shoreline landforms and the accumu-
lation and transport of near shore
sediment. The effects of upsetting
natural environmental conditions may
be forecast with considerable qualita-
tive precision.
In order to understand more com-
pletely the relations between hurri-
canes and their physical effects on
coastal lands, the following suggested
activities appear to be pertinent:
1. Accelerating the Weather Serv-
ice's program of hurricane
tracking and its ability to fore-
cast the intensity and time of
arrival of individual storms and
to designate the coastal areas
most likely to suffer.
2. Encouragement of studies by
coastal morphologists to iden-
tify areas where physical
changes are imminent, with em-
phasis on man-induced causes,
in the hope that they may be-
come expert in assessing the
results of undesirable practices.
3. Creation, on a national level,
of a group charged with moni-
toring proposed activities of
U.S. Army and other coastal
engineers from the standpoint
of assessing probable long-term
changes that designs of de-
fenses against the sea are likely
to induce. This should be a
cooperative, rather than strictly
policing, activity. There is tre-
mendous need for better com-
munication between scientists
and engineers. Scientists need
to be better informed about en-
gineering design practices, and
engineers need better under-
standing of the conclusions of
basic scientific research.
136
2. TORNADOES
Status of Tornado Research
Tornadoes are among the smallest
in horizontal extent of the atmos-
phere's whirling winds, but they are
the most locally destructive. Al-
though they are occasionally reported
from many places, it is only in the
United States that very intense tor-
nadoes occur frequently. A typical
intense tornado accompanies an
otherwise severe thunderstorm, lasts
about 20 minutes, and damages an
area a quarter of a mile wide along
a 10-mile path toward the northeast.
The maximum winds (never accu-
rately measured) are probably be-
tween 175 and 250 miles per hour,
but damage is caused as much by a
sudden drop of pressure, amounting
in extreme cases to about 0.1 of the
total atmospheric pressure, or 200
pounds per square foot. Especially
when structures are poorly vented,
roofs and walls are moved outward
by the higher pressure within; then,
as their moorings are weakened, they
are carried off horizontally by the
wind.
During the past 15 years, about
125 persons have been killed an-
nually by tornadoes. Average prop-
erty damage has been about $75
million. These figures may be com-
pared with estimated losses owing to
lightning, hail, and hurricanes as
shown in Figure V-6.
The high tornado death rate in
relation to property loss is attribut-
able partly to our inability to warn
effectively against impending torna-
does. A tornado is a very destructive
phenomenon, but it usually exists for
only a short time and affects only
the thousandth part of a region cov-
ered by tornado-spawning thunder-
storms. Extreme variability is an
essential characteristic. Most tornado
losses are associated with just a few
storms that utterly destroy the struc-
tures in significant portions of urban
areas or in whole small communities.
These events, sudden and never fore-
shadowed more than a few hours in
advance, leave the survivors stunned
amid desolation; they call for a sud-
den focused response, of a magnitude
akin to that demanded in war, by
the affected community and by state
and national governments.
Tornado Prediction
We have noted that the typical
tornado accompanies an otherwise
severe thunderstorm. Severe thunder-
storms are themselves hazards and
demand public forecasts, and the
possibility of tornadoes is usually
indicated when severe thunderstorms
are predicted.
Our forecasts, which must start
from a description of the present state
of the atmosphere, are less specific
than we would like. This lack of
specificity is associated in part with a
lack of knowledge, but also with
observations that are too sparse to de-
scribe atmospheric variability on the
scale of tornado or thunderstorm phe-
nomena. Thus, the extent of a severe
thunderstorm is 10 to 20 miles and
the lifetime of a storm system is
generally about six hours. But the
distance between first-line surface
weather stations is about 100 miles,
and between upper air stations about
150 miles. Observations are made
hourly at the surface stations (more
often under special conditions) but
usually at only 12-hour intervals at
the upper air stations. Therefore,
even if our knowledge were otherwise
adequate to the task, the observing
system would limit us to indicating
the probability of thunderstorms in
regions much larger than the storms
themselves.
At present, tornadoes are fore-
shadowed from one to six hours in
advance, for periods of about six
hours and in regions of about 25,000
square miles. About 50 percent of
such predictions are correct, with the
Figure V-6 — COMPARATIVE LOSSES DUE TO SEVERE STORMS
AND HURRICANES
Average Annual
Ave
rage Annual Property
Type of Storm
Deaths in U.S.*
Damage in U.S.*
Tornado
125
$ 75 million
Lightning
150
100 million
Hail
—
150 million
Hurricane
75
500 million
*Based on data from 1955-1970
Loss of life is almost four times greater from severe storms than from hurricanes,
while property damage is less than one-half as great.
137
PART V — SEVERE STORMS
incorrect forecasts being nearly di-
vided between cases without tor-
nadoes and cases with tornadoes
outside, but near, the predicted re-
gions. It should be noted that the
climatological expectancy of torna-
does during six hours in a randomly
selected 25,000-square mile area in
eastern and central United States is
only about one in 400. Plainly, then,
present forecasts give evidence of
considerable skill in identifying the
meteorological parameters associated
with severe storms and tornadoes
and in correctly anticipating their
development.
Briefly stated, the storm-forecast-
ing parameters are warmth and mois-
ture in a layer about 5,000 feet deep
near the earth's surface, with a cool
dry region at intermediate levels,
strong winds in the upper atmos-
phere, and a trend toward intensifi-
cation rather than diminution of these
conditions. The prediction of all the
necessary features is based on ob-
jective techniques, rooted in statistical
and dynamical evaluations and modi-
fied by the judgment of experienced
forecasters.
Forecasts of severe storms and tor-
nadoes one to six hours in advance
are considered "watches." In view
of the wide area covered by the
forecast relative to the area likely to
be affected, the public is encouraged
by a "watch" merely to remain alert
to further advisories. The forecasts
are disseminated by teletype from
the National Severe Storm Forecast
Center in Kansas City, Missouri, to
local offices around the country. Oc-
casionally, a local National Weather
Service office may issue a modified
local forecast which takes special
account of peculiar local conditions.
Since subscribers to the teletype
service include most elements of the
communications media, storm indi-
cations are quickly brought to the
attention of the radio and TV public.
Tornado Warning
Severe storms are observed as they
develop by Weather Service offices,
local government authorities, and
private persons. When the Weather
Service, through its own action or a
report by a private observer, becomes
aware that a severe storm or tornado
exists, a warning to communities in
the extrapolated path of the storm is
issued by teletype, or immediately by
radio and television if the situation
warrants. The public in the threat-
ened communities may be warned
by various actions of local authorities,
including the sounding of sirens. The
few minutes' warning thus provided
is credited with a twofold reduction
in loss of life. The greatest loss of
life from a tornado is often to be
found in the first community visited
by a storm, downstream locations
having the benefit of longer warning
time.
These days, observer reports are
valuably augmented by radar ob-
servations. The primary radar net-
work of the National Weather Service
has stations spaced 200 to 250 miles
apart. When severe storms threaten,
the radar screens are monitored con-
tinuously. The more intense echoes
are associated with heavier precipita-
tion and a greater likelihood of hail,
strong straight-line winds, and tor-
nadoes. Severe tornadoes are often
associated with a hook-shaped ap-
pendage on the echo. Thus, the
forecaster's observation of the intense
radar echoes provides a continual
check on visual sightings and damage
reports, and provides for timely
warnings to communities lying in the
projected path of a storm.
Tornado Research
Observations — Accurate descrip-
tion of tornado vortices and of the
atmospheric conditions preceding and
accompanying tornadoes is essential
for improved understanding and pre-
diction of tornadoes, and for the
possible development of practical
means for influencing tornadoes ben-
eficially. But scientific observation
of tornadoes is made difficult because
of their random occurrence, brief
duration, small size, and great vi-
olence.
In an attempt to study tornado
vortices directly, the National Severe
Storms Laboratory has maintained a
network of 30 to 60 conventionally
equipped surface stations during the
past seven spring seasons in an area
where tornadoes are relatively fre-
quent. Only two of the stations,
however, have been directly affected
by the winds of a tornado vortex
during this period. The network den-
sity would have to be increased by
a factor of 100 to obtain detailed
data on the wind distribution in tor-
nado vortices. For detailed informa-
tion on the vortices, therefore, we
are forced to rely on chance observa-
tions, engineering analysis of dam-
aged areas, eyewitness accounts, and
on the results of efforts to obtain
data remotely by photography and
by indirect probes such as radar.
Our information indicates that the
tornado is characterized by an inner
region where the winds decrease to-
ward the center, as in solid rotation,
and an outer region where the winds
fall off with increasing distance.
Many other tornado features are
highly variable. The tornado cloud,
presumed to be the surface of con-
stant reduced pressure at which the
well-mixed subcloud air is cooled to
saturation, varies in size and shape.
In some photographs it appears as un-
commonly smooth, suggesting lami-
nar flow, in others as highly irregular,
suggesting strong turbulence. Such
differences are quite important from
the point of view of tornado dynam-
ics. Since the less fierce waterspouts
are usually cylindrical and smooth-
walled, we are led to search for sig-
nificant variability in surface rough-
ness or atmospheric conditions over
land to account from the apparent
variability of turbulence and shape
of tornadoes.
The electrical properties of the tor-
nadoes also appear highly variable.
Finley's report on 600 tornadoes, pub-
lished in 1882, lists the observation
of thunder and lightning in 425 asso-
138
TORNADOES
ciated rainstorms. In 17 cases, lumi-
nosity of an apparently electrical
origin was noted in the tornado fun-
nel itself, while in 49 cases the ab-
sence of any electrical indication in
the cloud was specifically reported.
More recently, interest in electrical
theories was stimulated when Jones
reported unusual 100-kHz radiation
from a tornadic storm. Vonnegut
presented an electrical theory of tor-
nadoes; Brook has reported on the
magnetic anomaly observed during
touchdown of a tornado near Tulsa;
and Weller and Waite have proposed
that tornadoes are associated with
intense electromagnetic radiation at
television frequencies. On the other
hand, Gunn measured the electrical
activity of the tornadic storm that
devastated Udall, Kansas, on May 25,
1955, and found it to be "more or
less typical of exceptionally active
storms." Rossow has measured mag-
netic fields over numerous water-
spouts and found little disturbance.
Kinzer and Morgan located the posi-
tion of sferics sources in the tornadic
storm in Oklahoma on June 10, 1967,
and reported no obvious connection
between areas of cloud lightning and
tornado locations.
In a sense, the tornado itself is only
an important detail of the circulation
and energy balance of the larger
thunderstorm. By virtue of its larger
size and greater frequency, the typical
parent thunderstorm lends itself much
more to detailed examination. There-
fore, present research is concentrated
on identifying details in atmospheric
structure associated with formation
of tornadic and non-tornadic storms,
with the variable behavior of different
storms that form in the same general
area, and with the evaluation of the
way forces manifested in the storm
environment combine to produce ma-
jor features of the in-storm motions.
To this end, experimental networks
of closely spaced surface and upper
air stations are used along with quan-
titative radar and specially instru-
mented aircraft.
We have learned that severe and
enduring tornadoes form near the
small low-pressure areas associated
with the hook-shaped radar echo
marked by the arrow in Figure V-7.
Within the last decade the combina-
tion of observations and data gath-
ered by many sensors at one place
has taught a great deal about major
features of thunderstorm circulation
and, indeed, has revealed important
but hitherto unidentified distinct
storm classes.
Mathematical Modeling — All
present-day mathematical models of
weather represent extreme simplifica-
tions of the natural phenomena. We
are still especially far from simulat-
ing realistically and in combination
the many factors associated with the
development of local storms.
Most adequate for their purpose
are the models of atmospheric be-
havior on the scale oi
culation and large weathe
In use at the National Mcteoro
Center in Washington, D. C, such
models predict the general patterns
of horizontal wind, moisture, and
vertical currents; they provide useful
guidance to the thunderstorm fore-
caster, who combines their indications
with his knowledge of the distribu-
tion of features specifically associated
with local storms — and with his
judgment — to forecast the probable
location of storms. Models that fore-
cast directly the parameters known
to be important to thunderstorm de-
velopment are just beginning to come
into operational use. Some incorpo-
rate both dynamical and statistical
methodology and provide somewhat
more detailed spatial distributions
over the United States than has been
available heretofore.
Figure V-7 — RADAR VIEW OF A HOOKED ECHO
The picture is of a Plan Position Indicator (PPI) presentation of a severe storm over
Oklahoma City on May 26, 1963. Range marks denote intervals of 20 nautical miles.
North is toward the top. The radar is located at the center of the range circles.
The arrow points out the location of the tornado.
139
PART V — SEVERE STORMS
Local convective phenomena are
significantly affected by a greater
variety of processes and factors than
widespread weather, and are corre-
spondingly more difficult to model
realistically. To date, we have some
two-dimensional models that incor-
porate simplified formulations of pre-
cipitation-related processes and of
entrainment. These show some skill
in predicting, for example, the maxi-
mum height to which a cloud tower
rises with specified ambient condi-
tions. The most comprehensive of
today's models, however, is probably
less detailed by a factor of at least
100 than one that would illustrate
significant features of the asymmetric
horizontal and vertical structure.
Today's mathematical models of
the tornado itself treat cylindrically
symmetric cases. At the edge of
knowledge, we find steady-state mod-
els such as Kuo's, which appears to
describe essential features of observed
tornadoes in terms of an unstable
vertical stratification and an ambient
field of rotation. The fact that these
features are often present when tor-
nadoes are absent, however, serves to
emphasize that we still have very far
to go in our modeling and observing
to identify the factors responsible for
concentrating angular momentum in
the developing tornado.
Experiments — The control of pa-
rameters afforded by laboratory con-
ditions recommends the experimental
approach to identification and analy-
sis of factors responsible for the
growth of tornadoes. Such experi-
ments have been conducted for many
years, often in conjunction with theo-
retical investigations, and realistic-
appearing vortices have been pro-
duced in various liquids and in air
under a considerable variety of ex-
perimental conditions. The very ease
with which tornado-like vortices can
be produced experimentally has made
it difficult to progress much beyond
theoretical implications regarding the
development of swirling motion in
converging fluid at the base of a ris-
ing column, and the important influ-
ence of boundaries.
Concurrent with the recent devel-
opment of numerical analysis of
large-scale atmospheric circulations,
however, has come appreciation of
the importance of similarity both in
theoretical and experimental model-
ing. Similarity in flows on different
scales is said to exist when the ratios
of various quantities involving inertia,
viscosity, rotation, and diffusion are
the same. Considerations of similar-
ity, and increased attention to such
natural observations as are available,
are leading to design of models more
revealing of the effects of natural
conditions.
Thus, Turner and Lilly have con-
structed physical models of vortices
driven from above to simulate the
convection in a cloud, and have found
rising motion in the vortex core with
descending motion in a surrounding
annulus. Ward, noting that no tor-
nado vortex can be indefinitely long,
has ingeniously separated a fan from
the vortex it creates in controlled in-
flow beneath. In this model, his con-
trol of the inflow angle and depth of
the inflow layer represent the most
important influences in the creation
of a vortex, its intensity and diameter,
and, in contrast to earlier models, the
development of a central downdraft.
The problems of developing theo-
retical and experimental models in-
dicate the importance of observations
on even gross characteristics of tor-
nado circulations. Is the flow upward
or downward in the funnel core?
How is tornado behavior, such as
funnel-skipping, related to the rough-
ness of underlying terrain? What is
the wind inflow angle and air pres-
sure at various distances from the
visual funnel? How does the wind
vary with height in the vicinity of
tornadoes? If we could better answer
these questions for atmospheric cases,
we could design experiments accord-
ingly, and rationally extend our
search for influential parameters of
the flow.
Comments on Investigational
Techniques
We have surveyed observational,
theoretical, and experimental aspects
of tornado investigations. The vari-
ety and complexity of processes im-
plicit in tornado development and
maintenance, and the rarity, relatively
small scale, and intensity of the natu-
ral phenomena have been sources of
great difficulty. Let us briefly con-
sider the helpful technological ad-
vances that may reasonably be antici-
pated and whose development should
be encouraged.
Emerging Observational Tech-
niques — With regard to observa-
tions, no available prototype tech-
nique seems practical for measuring
details of the distribution of velocity
and other parameters in a tornado
vortex. With the encouragement of
severe-storm study programs, how-
ever, greater numbers of observations
— including useful motion pictures —
should become available, and we may
reasonably expect an opportunity in
the next few years to extend the im-
portant study of the Dallas tornado
of April 2, 1957, made by Hoecker
and his colleagues.
Emphasis should be placed on ob-
serving the circulations around severe
storms, since it is certain that the
intensity of a storm and the occur-
rence of tornadoes is greatly con-
trolled by the storm environment. In
addition to encouraging existing pro-
grams having this objective, we may
put special emphasis on two emerg-
ing tools. One is meteorological
doppler radar, which in units of two
or three can map the distribution of
precipitation velocity with unprece-
dented detail. The development of an
improved doppler capability would
have value both for fundamental re-
search and for research on an im-
proved warning system, the latter by
providing bases for evaluating the
distinguishing features in a storm
velocity field characteristic of an im-
pending tornado. Doppler capabil-
ity for clearer tornado identification
140
\DOES
needs to be assessed. Although some
meteorological doppler radars are
presently in use and other systems
are under development, the pace of
work seems slow.
The second emerging technique is
satellite infrared spectrometry, which
is providing new detail on the vertical
thermal stratification of the atmos-
phere at intervals of about 30 miles.
Further development of the satellite
system should result in better analy-
sis of severe thunderstorm precursor
conditions over the United States and
refinement of our forecasting ability.
Computers — With regard to
mathematical modeling, greater real-
ism will be possible as computers
become larger and faster and as theo-
retical models are revised in light of
observations and experimental re-
sults. Of course, many techni-socio-
logical forces are already encouraging
the development of improved com-
puters. We may emphasize here that
no conceivable computer can ever
solve meteorological problems in such
a way that careful scientists will
not be an essential part of problem
preparation; indeed, theoretical in-
terpretation of data from observa-
tional and experimental programs
will be increasingly required to de-
velop reasonably posed mathematical
formulations.
Physical Models — With regard to
physical modeling of thunderstorms
and tornadoes, the difficulties inher-
ent in modeling significant atmos-
pheric processes such as condensa-
tion and precipitation, in diminishing
the effect of container sidewalls to
levels consistent with the atmos-
phere's lack of sidewalls, and in
simulating the vertical density gra-
dient and diffusion processes charac-
teristic of the atmosphere will con-
tinue to represent serious obstacles.
These problems have been less seri-
ous with respect to interpretation of
the more essentially two-dimensional
flows representative of atmospheric
circulations on larger scales. Never-
theless, experimental methods should
continue to be important for testing
tornado hypotheses and suggesting
new lines for observational and theo-
retical study.
The General Status of the
Operational System for Severe
Storm Prediction and Warning
Present-day severe-storm forecasts
are immensely valuable, but we wish
they were more precise and more ac-
curate. Although numerical methods
have been used for forecasting large-
scale weather patterns for over ten
years, the development of mathemati-
cal models relevant to the smaller
scale of local storm complexes is still
in its infancy. Basic improvements
in the quality of severe-storm fore-
casts depend on the development of
new understanding of storm struc-
ture and dynamics, the interaction
between severe local storms, and
the larger patterns of air motion
that establish the general conditions
favorable for storm development. As
previously indicated, such improved
understanding can be expected to
evolve only as the insights provided
by more detailed observations are
assessed by careful scientists with the
aid of more powerful computers.
Eventually, methods will be devel-
oped combining such detailed data as
that provided by radar and satellites
with other weather parameters in
dynamical storm models; appropriate
ways to use such detail in operational
forecast preparation should then be-
come clear.
At present, we can strive to hasten
the preparation and distribution of
such forecasts as we have. To this
end, hand analysis of patterns signifi-
cant to local storm development is
being significantly replaced by com-
puter techniques. The radar network,
which is the backbone of the system
used for severe-storm warning, also
lends itself to significantly advanced
automation. Displays like that shown
in Figure V-7 can be replaced by
contour-mapped echo representa-
tions. (See Figure V-8) A correspond-
ing digital array can be pro<
simultaneously (see Figure V 9) as a
basis for automatic preparation and
dissemination of extrapolation fore-
casts. In midwestern United States,
the Weather Service is presently
starting to develop an operational
test of advanced radar systems in
order to evaluate the probable costs
and benefits of various system de-
signs for nationwide application.
Prospects for a Measure of
Tornado Control
The energy production involved in
one severe local storm is comparable
to the total power-generating capacity
of the United States. Thus, the
control of severe-storm phenomena
clearly requires an ability to direct
far greater amounts of energy than
those locally applied by man at pres-
ent. This will depend on developing
knowledge of how to modify the
processes by which nature's supply is
utilized. For example, silver iodide
and a few other chemicals are used to
stimulate the freezing of water drops
that otherwise remain liquid during
cooling to temperatures somewhat
below their melting point; the arti-
ficial release of the latent heat of
fusion thus achieved can raise the air
temperature enough to enhance sig-
nificantly the growth of some clouds
and to hasten the dissipation of
others. Conceivably, this kind of
process could be applied to alter na-
ture's choice for rapid growth among
a host of nearly identical clouds.
Other means for modifying torna-
does might involve alteration of the
earth's topography and roughness to
decrease the probability of tornadoes
over inhabited areas, and the direct
application of heat at a point in time
and place where such application
would beneficially modify the course
of subsequent events. It must be
plain from the foregoing discussion,
however, that we are still very far
from having a reasonable basis even
for estimating the likelihood that such
efforts could ever be successful.
141
PART V — SEVERE STORMS
Figure V-8 — CONTOUR-MAPPED PPI DISPLAY
The figure shows the PPI-scope of the 10-centimeter WSR-57 radar at the National
Severe Storms Laboratory in Norman, Oklahoma on April 26, 1968. Differences in
shading indicate intervals of a factor of 10 in received echo power. From such an
electronic display it is possible to determine the most dense part of a storm. Range
marks are at intervals of 20 nautical miles. North is at the top of the figure.
142
ADOES
Figure V-9 — CONTOUR-MAPPED DIGITAL DISPLAY
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The figure shows a digital version of the data shown in Figure V-8. The successive
horizontal lines represent 2° steps of azimuth. These are noted in the leftmost
column. The vertical lines represent 20-nautical-mile intervals, the dots at the top
and bottom of the diagram represent one-nautical-mile intervals. Successive digits
on the map represent factors of seven in the echo intensity.
143
TART V — SEVERE STORMS
Tornadoes — Their Forecasting and Potential Modification
A tornado, also called cyclone or
twister, is defined as a violently rotat-
ing column of air, pendant from a
cumulonimbus cloud, and nearly al-
ways observable as a funnel. The
shape of a funnel varies from a cone
to a rope; its lower end does not
always touch the ground. A con-
firmed small tornado could be char-
acterized by a damage area of 10,000
square feet, while the swath of a
giant tornado covers more than 30
square miles. Thus, a giant tornado
could be 50,000 times larger than a
tiny one in terms of potential damage
area.
The annual tornado frequency
changed from a minimum of 64 in
1919 to a maximum of 912 in 1967,
which represents a ratio of 1:14. This
does not mean that tornado frequency
increased by at least one order of
magnitude. Instead, reporting effi-
ciency — related to the reporting sys-
tem, urban development, population
density, and such — probably in-
creased the apparent tornado fre-
quency. It is preferable, therefore, to
evaluate the potential danger of tor-
nadoes according to damage areas
rather than their number of occur-
rences.
Damaging Tornadoes
When a tornado warning is issued,
the general public will be looking for
the nearest storm shelter for protec-
tion of life. Statistics show, however,
that 50 percent of the total tornado
damage area is produced by only 4
percent of the tornadoes. This means
that half of the potential damage
area can be warned efficiently if the
top 4 percent of tornadoes are pre-
dicted with great accuracy. If the top
10 percent of tornadoes can be pre-
dicted, their damage area would cover
75 percent of the total damage area.
Although these statistics do not sug-
gest that only large tornadoes should
be predicted to the neglect of others,
accurate prediction of large tornadoes
would be of great value to local
residents.
Small Tornadoes — The origin of
large, long-lasting tornadoes seems to
be quite different from that of the
tornadoes at the small end of the size
spectrum. Small tornadoes and water-
spouts are so similar in dimension and
appearance that the former can be
regarded as waterspouts traveling
over land. These small storms, al-
though they make up a large number
of all storms, are very difficult to
predict. They may form within a local
shear line associated with growing
cumulus clouds that may or may not
become thunderstorms. Small torna-
does last only a few minutes, leaving
a damage swath of only a few miles.
Hook-Echo Tornadoes — Large tor-
nadoes frequently last 30 to 60 min-
utes. Furthermore, in many cases
several tornadoes of similar size and
intensity appear one after another,
thus forming a family of large torna-
does. When radar pictures of proper
gain and of low elevation angles are
examined, almost all tornadoes in
such a family are related to a thunder-
storm echo with rotational character-
istics— i.e., a rotating thunderstorm is
a spawning place for one to several
large tornadoes.
When the view is unobstructed, a
rotating thunderstorm can be photo-
graphed at large distances as a bell-
shaped cloud with an over-all diame-
ter of 5 to 25 miles. The same cloud
would appear in a plan-position-
indicator (PPI) radarscope as a "hook
echo," with an eye at the rotation
center and several echo bands spiral-
ing around the eye-wall circulation.
Despite the fact that a family of
tornadoes comes from a rotating
thunderstorm, not every rotating
thunderstorm or hook echo spawns a
tornado during its lifetime. It is likely
that only a maximum of 50 percent
of hook echoes spawn tornadoes —
usually large ones. Hook-echo torna-
does are responsible for more than
half of the damage areas caused by
all tornadoes.
Detecting Large Tornadoes — The
above evidence leads to the conclu-
sion that large tornadoes spawn from
mesoscale vortex fields identified as
rotating thunderstorms, hook echoes,
or tornado cyclones. The outermost
diameter of such a vortex ranges be-
tween 5 to 25 miles. The eye, sur-
rounded partially or totally by a hook-
shaped echo, rotates at the rate of
20 to 40 miles per hour at its outside
edge and is 1 to 3 miles in diameter.
The central pressure of a tornado-
bearing mesoscale vortex or tornado
cyclone is only 2 or 4 millibars lower
than its far environment. An imprac-
tically large and expensive network
of barograph stations would be re-
quired for detecting tornado cyclones.
Unless a doppler radar network be-
comes available in the future, PPI-
scope pictures in iso-echo pres-
entation with better than one-mile
resolution will provide the only means
of detecting tornado cyclones within
some 10 minutes after their formation.
Early detection of tornado cyclones
is the key to a warning within a
narrow zone in which there is a
chance of tornado formation. Such
an alley is only 5 miles wide and 50
miles long on the average, while a
tornado watch area extends 50 x 100
miles, some 20 times larger than one
alley area.
Maximum Tornado Windspeed
Windspeed is an important pa-
rameter, necessary for the design of
tornado protective structures. When
settlers first experienced the impact
of tornadoes in the Midwest, they
estimated maximum windspeed to
144
be in excess of 500 miles per hour.
Some even estimated a supersonic
speed.
Damage investigation since then
has reduced general vvindspeed esti-
mates to between 300 and 500 miles
per hour. If these maximum-speed
estimates are accurate, they would,
where combined with the storm's
pressure reduction, make it impossi-
ble to construct tornado-proof struc-
tures at reasonable cost.
Fujita's study of tornadoes during
the past ten years, however, has now
led to the conclusion that the maxi-
mum windspeed of tornadoes is much
less than previously thought. Maxi-
mum rotational windspeeds, as esti-
mated from scaling motion pictures
and characteristic ground marks, are
about 200 miles per hour. The trans-
lational motion of the storm must be
added to the right side and sub-
tracted from the left side of the rotat-
ing core. If a tornado travels at its
average speed of 40 miles per hour,
the maximum combined speed above
the frictional layer would be 240
miles per hour. Some tornadoes, such
as the ones on Palm Sunday, 1965,
traveled eastward at 62.5 miles per
hour. For these storms, the maximum
combined windspeed would be 260
miles per hour. Inside the boundary
layer, the gust speed must be added
to the mean flow speed, which de-
creases toward the ground. Under
the safe assumption that the peak
gust speed could overpass the de-
crease in the flowspeed toward the
ground, a maximum gust speed of
300 miles per hour seems to be quite
reasonable. Thus, one has:
Maximum rotational speed. . . .200 mph
Maximum traveling speed 70 mph
Maximum gust speed 300 mph
It should be noted that the higher
estimated speeds were obtained by
assuming the cycloidal ground marks
were produced by one rotating object.
Fujita's study has indicated that there
are 3 to 5 spots which produce cy-
cloidal marks. Thus, the speed for
any one tornado of a family must be
reduced bv one-third to one-fifth.
Minimum Pressure Inside
Tornadoes
As in the case of tornado wind-
speed, in earlier days pressure reduc-
tion at the center of tornadoes had
been overestimated to be a near
vacuum or 2,000 pounds per square
foot. Since then, meteorologists have
tended to agree that the pressure re-
duction at the storm center is between
200 and 400 millibars.
It should be noted that a building
will suffer also from differential pres-
sure from its form resistance. A 300
miles per hour wind will produce a
positive stagnation pressure of about
90 millibars at its windward side.
Over the roof, however, the pressure
may be negative, with the result that
the roof is lifted. (The lifting force
cannot be estimated unless the com-
plete shape of the building is given
and a wind-tunnel test is performed.)
Potential Tornado Protection and
Modification
As a result of more recent wind-
speed and pressure estimates, criteria
for designing tornado-resistant struc-
tures have now become feasible. Such
structures could be expensive, al-
though future designs and improved
material could reduce costs to a level
where at least public buildings in a
tornado alley could be built to with-
stand tornado wind and pressure.
Tornadoes vary in both shape and
size. The most commonly observed
four shapes are:
Cone shape: Large tornadoes drop
down in the shape of a cone; as
the storm develops, the tip of
the cone reaches the ground.
Column shape: A tornado or a
large waterspout takes the shape
of a large trunk.
Chopstick shape: Thi
shape of weak tornadoes and
waterspouts with small diame-
ters.
Rope shape: When tornadoes be-
come very weak, they change
into a rope which often extends
miles in a semi-horizontal direc-
tion.
Although tornadoes have such
different shapes, all tornadoes and
waterspouts are characterized by a
core circulation surrounded by a cir-
cle of maximum wind. Outside this
circle, the tangential windspeed de-
creases in inverse proportion to the
distance from the circulation center.
Chopstick- or rope-shaped tunnels
may be considered axially symmetric.
When the core diameter increases, as
in the case of the cone and trunk
shapes, there are several spots of
strong suction around the edge of the
core; thus, they are no longer axially
symmetric. These spots of strong
suction rotate around the funnel at
the speed of the funnel rotation.
Three ways of modifying tornado
windspeed may be considered. They
are: (a) a reduction of the circulation
energy; (b) an increase in the core
diameter without changing the circu-
lation intensity; and (c) reduction of
the windspeed near the ground.
Reducing the Circulation Energy
— This possibility depends on the
counteracting energy that can be cre-
ated artificially. The total kinetic
energy of a tornado is on the order
of 107 kilocalories, which is just about
1/1,000 of a small, 20-kiloton atomic
bomb. The energy of even the largest
of tornadoes is comparable only to
1/100 of the energy in a small atomic
bomb. Atomic bombs obviously can-
not be used to modify a tornado.
We might however, investigate such
power sources as an artificial jet in
order to learn more about how the
relatively small and concentrated en-
ergy of a tornado might somehow
be dispersed.
145
PART V — SEVERE STORMS
Increasing the Core Diameter —
This definitely reduces the maximum
tornado windspeed that occurs just
outside the core. Modification of hur-
ricanes through eye-wall seeding is
based on the similar principle in
which the release of latent heat
around the eye wall will literally ex-
pand the eye diameter, thus reducing
the extreme pressure gradient around
the eye. In the case of tornadoes, it
might be possible to cool the lowest
portion of the core circulation. If we
inject water droplets into the core at
a certain level between the ground
and the cloud base, they will evapo-
rate as they slowly centrifuge out,
thus cooling the core to increase the
descending motion inside the core.
The lower portion of the core will
then expand, reducing the maximum
windspeed.
Contrary to older reports, a tor-
nado cannot suck up a body of water
beneath its core. Investigation of
ground marks has revealed that the
suction power of a tornado is weaker
than a suction head of a household
vacuum cleaner placed closed to the
surface. It is, therefore, necessary to
deliver a large amount of water in
drop form into the core.
Reducing Windspeed Near the
Ground — This could be achieved by
constructing a number of deflectors
to the west and southwest of an im-
portant structure such as an atomic
power plant. The deflectors should
be oriented in such manner that they
change the southeast winds on the
advancing side of a tornado to a
northeast wind or possibly to a north-
northeast wind, thus creating a flow
converging toward the tornado cen-
ter. The net effect of the convergence
will be to reduce the speed near the
surface. Design of deflectors should
be made through aerodynamic calcu-
lations and a wind-tunnel test.
Other Activity
Methods of estimating tornado
windspeed should be explored and
tested whenever feasible. Direct
measurement is desirable if "maxi-
mum wind indicators" are to be de-
signed to stand against tornado wind.
Measurement of object motion inside
the tornado does not always give the
air motion. Especially when an explo-
sion of a structure is involved, the
initial object velocity is likely to be
overestimated. The designing of a
low-priced "minimum-pressure indi-
cator" for placement over the area of
expected tornado paths is also recom-
mended.
Basic research on tornado modifi-
cation also needs to be carried on
through various model experiments
and theoretical studies. Furthermore,
although the probability of tornadoes
is small, some important structures
must be protected against severe
destruction.
Tornado Forecasting and Warning
Tornado frequency within the
United States varies from 600 to 900
per year, with the major concentra-
tion through the Central Plains.
Ninety percent of all tornadoes have
a path-length between 0.5 and 50
miles and path-width between 40 and
800 yards. The median tornado has
a path-length of 5 miles with a path-
width of 200 yards. The median
destructive period is less than 30
minutes. Less is known about tor-
nado velocity profiles, but one can
estimate that 90 percent of the peak
speeds are between 100 and 225 miles
per hour, with a median peak velocity
of 150 miles per hour. Unfortu-
nately, the upper limit appears to be
around 300 miles per hour.
Thus, the problem is to forecast
the occurrence of a rare meteorologi-
cal event which has median dimen-
sions of one square mile over a
30-minute period, and to forecast it
sufficiently far in advance to allow
effective use of forecasts by all in-
terested parties. There should be
suitable differentiation for tornado
classes based on width, length, and
peak velocity. None of the above is
possible at this time for areas of
less than several thousand square
miles and for more than one hour in
advance.
Matters Contributing to the
Forecast Problem
Data Network — The average dis-
tance between full-time surface re-
porting stations is 100 miles. Reports
are made every hour, oftener when
special criteria are met. Unless the
special report is taken and trans-
mitted near a free time-period in the
teletype schedule, it is quite probable
that the report will be delayed 10
minutes in reaching the user. Thus,
the spacing and frequency of reports
taken with the standard data network
is not adequate to fully describe the
severe weather events taking place
within the confines of the data net-
work.
The average distance between
upper air stations is 150 miles — and
slightly more than that in the areas
of high tornado incidence. Rawin-
sonde releases are scheduled only
every 12, and on occasion every 6,
hours. But the 1200 Greenwich Mean
Time (GMT) release is made in the
Midwest at 6 a.m. Central Standard
Time (CST), a minimum thunder-
storm period, while the midnight
GMT release is made at 6 p.m. CST,
a maximum thunderstorm period. Ef-
fectively, this produces only one use-
ful report per day per station. These
reports are not adequate to fully de-
scribe the temperature, moisture, and
wind patterns within the tropo-
146
,DOF.S
sphere. This is due partly to their
spacing and frequency and partly to
errors inherent in the equipment.
In addition, there are data voids
in the areas surrounding the United
States, such as the Gulf of Mexico,
the Atlantic waters adjacent to the
east coast, and portions of Mexico
and Canada. All of these contribute
to serious lateral boundary prob-
lems, the most pressing being the
Gulf of Mexico. Texas, Louisiana,
Mississippi, Alabama, Florida, and
Georgia are all high-incidence areas
for destructive tornadoes, and the
lack of any direct meteorological data
over the Gulf of Mexico has made
objective analysis and prediction dif-
ficult.
To augment the conventional sur-
face and upper air networks, use has
been made of radar and satellite
photographs. The processing and
display of either method is still in
its infancy; considerable experimenta-
tion will be required to obtain con-
tinuous readout of radar- and satel-
lite-produced information. At present,
neither the radar nor satellite output
is woven into conventional analyses
in a systematic and objective manner.
Forecast Methods — Present meth-
ods are largely subjective, drawing
heavily on case studies and the ex-
perience of the individual forecaster.
This is slowly being replaced by
objective, computer-oriented methods,
partly dynamical and partly statisti-
cal. (See Figure V-10) Considerable
improvement is needed for either
method. The most promising avenue
for dynamical methods concerns the
development of a fine-mesh primitive
equation model for multi-layers. Such
a model would be of limited value at
this time because of the data limita-
tions noted, but it will become in-
creasingly important as the average
spacing between stations is reduced.
The statistical approach involves a
search for predictors through the use
of multiple-screening regression tech-
niques. It has not been possible to
gather all of the possible predictors
Figure V-10 — SEVERE WEATHER WARNING
TIME OF
ECHO 2 EST. VEL.
AT2115CST=:256/23
CLOSEST
DIST.
3 SIGMA
APPROACH
AIRPORT
AND DIR.
TIME LIMITS
2139
CUSHING
12.5 N
2125 2154
2148
STROUD
23.5 N
2131 2205
2148
PAWNEE
12.4 S
2131 2205
2152
HOLDENVILLE
18.0 N
2133 2210
2200
ATOKA
21.3 N
2140 2221
2217
BRISTOW
25.2 N
2152 2242
The table illustrates an experimental severe weather warning of a thunderstorm
cell moving from 256° at 23 knots. The warning gives the time of closest approach
to airports near the forecast path. It also gives the distance and the direction of
the echo from the airport. Finally, it estimates potential error of the forecast in
terms of the time period of closest approach. This warning was prepared auto-
matically by a computer using statistical properties of radar echoes such as those
measured in Figures V-8 and V-9.
along with tornado occurrences, so
this approach will require further
work.
Research and Development — Com-
paratively little research on forecasts
is being performed in this country.
In allied fields, considerable research
and development is under way on
hail suppression, doppler radar,
LIDAR (light detection and ranging),
and remote-sensing techniques. Im-
proved equipment and techniques will
have application to the warning prob-
lem.
Modeling
Several theories have been ad-
vanced to explain the Great Plains
tornado. These theories do not, how-
ever, explain the hurricane-induced
tornado, the western U.S. tornado,
or the waterspout. A great deal more
work is needed in modeling tornado
formation.
Prediction Techniques
The same problems apply to the
warning as to the forecast. A vast
majority of reported tornadoes do not
come close enough to any of the
reporting stations to be detected, ei-
ther visually or by instruments.
Radar Detection — The radar net-
work is being expanded throughout
the United States, using 10-centimeter
radar. This is effective to 125 nautical
miles in defining severe thunder-
storms capable of producing torna-
does, but even a highly skilled radar
operator cannot clearly identify a
tornado by radar or give a 15-minute
forecast that a certain cloud will
produce a tornado. Certain charac-
teristic shapes provide some informa-
tion on the probability of tornadoes,
but the pattern is not present for
every tornado.
Instrument Detection — There are
no mechanical methods at this writ-
ing that can make an objective dis-
tinction between the pressure fall or
rise produced by a strong squall line
and that produced by a tornado.
Even if there were such a device, the
spacing required to insure its useful-
ness would be prohibitively expen-
sive.
Volunteer Spotters — Most warn-
ing is based on a combination of
147
PART V — SEVERE STORMS
radar detection and visual spotting, warning is a function of the spacing is needed on "steering methods" for
usually performed by volunteers. of the spotters. tornadoes once they are known to
This gives uneven results at best, exist. No work at all has been done
since the ability of the spotter is as To be of maximum value a warning to determine how long a tornado will
much a function of his zeal as any- should be as specific as possible with be in contact with the ground once
thing else. The timeliness of the regard to area and time. More work it has been detected.
148
3. HAIL
Hailstorm Research and Hail Suppression
Hailstorms belong to those atmos-
pheric phenomena whose life history
originates and terminates in the
mesoscale range — i.e., their size
ranges from about 1 to 100 kilo-
meters. Phenomena of this scale pre-
sent great difficulties for observation
and description, and the means and
instrumentation for that purpose are
only now being developed.
Radar, the oldest tool of mesoscale
observation, has been somewhat dis-
appointing when quantitative data are
required. A system that combines
airborne radar with data derived from
the aircraft's doppler navigation sys-
tem has proved to be a powerful tool
for storm studies. The radar helps to
delineate the precipitation echo of
the storm while the doppler system
provides the wind vector at flight
level. Thus, on circling the storm,
the line integrals for divergence and
vorticity can be solved, and these
yield the inflow into the storm
throughout its life history.
The improved means of storm ob-
servation have de-emphasized the
classical approach to storm research.
This approach attempts to find,
through observation and deduction,
one valid storm model that satisfies
all hailstorms. The last such model
was derived by Browning from radar
observations of one storm in England.
It was characterized by a slanted
updraft and an echo-free vault — i.e.,
an area where the main updraft
speed was concentrated and where,
due to the high updraft speed, no
large particles accumulated that
would cause radar reflections.
Hailstorm Characteristics
Nowadays we know that hail-
storms appear in many manifesta-
tions. The energy source is always
the latent energy of condensation,
but in the exploitation of that energy
the vertical wind profile appears to
assume an important role. Over the
Great Plains of the U.S., hailstorms
usually travel from west to east.
They can grow and form new cells
from the leading (eastern) edge or
from their trailing (western) edge;
thus, they can actually grow from
the rear. It appears that their updraft
is usually upright and not slanted
even under conditions of strong wind
shear; more and more, they are re-
garded as aerodynamic hindrances in
the large-scale atmospheric flow re-
gime, with the wind going around
and over the storm. Thus, the up-
draft tower may be eroded on the
outside by the horizontal wind but
remain undisturbed in the interior.
The air intake into a growing cell
is of the order of 10 cubic kilometers
per minute. High wind velocity in
the anvil level appears to be the
mechanism that prevents early decay
of the cell, since precipitation and
liquid water are carried away from
the cell and, consequently, do not fall
back into and "suppress" the updraft.
It has been shown that hailstorms
occur with special frequency in jet-
stream regions of the United States,
Europe, and India and that the com-
bination of convective storms and
jet stream can produce a very efficient
and abundant precipitating cloud sys-
tem. There are indications that the
effectively producing hailstorm is
characterized by high latent instabil-
ity, inflow from the right rear quad-
rant, and strong wind shear aloft.
Very poorly understood is the way
hailstorms become organized. As yet,
we do not know under what condi-
tions many small storms or a few
big ones form, what causes the storms
sometimes to align themselves in
rows and sometimes to form in clus-
ters. It has been speculated that
differences of surface temperature be-
tween sunlight and shadowed areas
may cause local seabreeze-type cir-
culations which contribute to the
organization of inflow areas.
Some conditions lead to self-
enhancement of storm intensity. For
example, when the storm moves over
its own precipitation area and en-
trains moist air, the base level is
lowered, which in turn increases the
buoyancy. This will increase the in-
flow into the storm, which then leads
to an increased diameter of the up-
draft column. This causes an increase
of updraft speed for the same latent
instability because the ratio between
buoyancy forces and drag forces has
shifted in favor of the buoyancy
force.
Theoretical Studies
Theoretical studies of the dynamics
of storms extend in two general di-
rections:
Analytical Studies — These studies
deal with the influences of buoyancy
and water-loading on updraft speed
and radial divergence when the
buoyancy term is compensated by the
weight of the cloud and precipitation
water. Essentially, this research aims
at appraising the existence of an
"accumulation level" of cloud water
in the upper regions of the storm.
According to Soviet scientists, the
accumulation level is characterized by
a high liquid-water content, since the
local derivative of the updraft speed
149
PART V — SEVERE STORMS
versus height is negative
(£<•)
above that level and positive below
it. As long as the maximum updraft
speed is greater than 10 meters per
second, water drops will neither de-
scend below the accumulation level
nor ascend much above it. Therefore,
liquid water may become trapped at
a certain layer and provide conditions
for the rapid growth of hailstones.
While the existence of such a level
is possible, the rapidly increasing
water-loading will, for continuity rea-
sons, cause a strongly divergent flow
that discharges the accumulating wa-
ter content radially in a short time.
Numerical Studies — Several at-
tempts are under way to expand one-
or two-dimensional numerical cumu-
lus-cloud models into convective
storm models. Even two-dimensional
models, however, are much too prim-
itive for the simulation of a phe-
nomenon as complex as a hailstorm.
The best model to date appears to
be a time-dependent, two-dimensional
model developed by Orville; however,
even this model puts severe strains
on computer capacity and memory.
There can be no question that these
attempts are only first steps and that
much research and data collection is
required to make them realistic.
Microphysical Studies
Microphysical studies aim, partic-
ularly, at an explanation of hailstone
structure and the application of hail-
stone features to explain the condi-
tions under which it has grown. It
is hoped that hailstones can be used
as aerological sondes which even-
tually may reveal their life history
and, consequently, the environmental
conditions inside the hail cloud. (See
Figure V-ll)
Here the investigator is confronted
with complexities related to greatly
varying growth conditions of ice due
to accretion of supercooled water.
The most thoroughly conceived the-
ory has been developed by List from
actual growth conditions in a hail
wind tunnel. However, List gives
consideration only to the accretion
of supercooled cloud water; ice struc-
tures resulting from the accretion of
a mixed cloud (ice crystals and water
droplets) or of aggregation of smaller
hail or graupel have not been studied.
The following general statements
may be made with caution:
Hailstone Structure — Most hail-
stones show a hail embryo in their
Figure V-1 1 — STRUCTURE OF HAILSTONE EMBRYOS
At the heart of almost every hailstone there is a distinct growth unit 5-10 millimeters
in diameter known as the embryo. The illustration shows the three most common
types: (1) Conical embryos consist of opaque crystals larger than 2 millimeters in
diameter, indicating formation between -20C and 0 C. These embryos fall in a
stabilized position, blunt end downward, so they collect droplets on only one
surface. This category represents about 60% of the hailstones studied. (2) Spherical
embryos of clear ice (25% of the hailstones studied) consist of large crystals or a
single crystal, indicating growth in clouds with temperatures above -20 C. Many
of these embryos have cracks caused by the freezing of internal liquid water. (3)
Spherical embryos of opaque ice (10% of the hailstones studied) have crystals of
intermediate size and air bubbles showing no particular arrangement. They may
have had a more complicated origin than other embryos, involving partial melting
and refreezing or even collection of snow crystals. Because they tumble as they
fall, they collect droplets equally on all surfaces.
150
HAI!
growth center. This embryo is conical
or spheroidal. It can be opaque or
clear ice. It is usually well recogniz-
able against the shell structure of the
remaining stone.
One may conclude that the life
history of a hailstone can be organi-
cally subdivided into two major pe-
riods: (a) growth in a hail embryo
during the development cloud stage
of the hail cell, and (b) growth in a
hail shell during the mature-hail-cell
cloud stage. It is conceivable that
the former occurs during the de-
velopment phase of the cumulonim-
bus or hail cell, the latter when the
penetrative convection has been es-
tablished and a strong supporting
updraft has formed.
Environmental Growth Condi-
tions — On the basis of List's theory
it is possible to derive four environ-
mental growth conditions from typi-
cal hailstone properties:
1. It is unlikely that hailstones
are usually grown in the high
water content of an accumula-
tion level; if that were true, one
should observe soft, spongy
hailstones much more fre-
quently.
2. It can be shown that hailstones
with many alternating layers
of clear and opaque ice may
have grown at high levels in
the cloud; at these levels, small
altitude variations cause large
variations of the growth con-
ditions.
3. Hailstone structures that are
homogeneous over a large part
of the shell indicate that they
have grown in an updraft with
continuously increasing updraft
speed.
4. The natural hailstone concen-
tration is of the order of 1 to
10 per cubic meter. This con-
centration effectively depletes
the cloud water content, as was
shown in 1960 by Iribarne
and dePena, which gives hope
that hailstones could be made
smaller and less damaging
through a slight artificial in-
crease in the concentration of
about two orders of magnitude.
Amounts of seeding material
needed to accomplish this are
moderate.
Hail-Suppression Experiments
The problem of hail suppression
is economic as well as scientific. One
of the questions to be answered is:
Does agriculture suffer sufficiently
from hailstorms that prevention is
necessary? Some people believe that,
as long as we have a farm surplus
and pay farmers for not planting
certain crops, we do not need hail
suppression. While this may be true
now, in coming years we may need
every bushel of farm crop for our
food supply. This appears to be a
good time, therefore, to begin a hail-
suppression research program. Re-
search must be emphasized, since
too little is known about the hail
mechanism to permit a realistic hail-
suppression program to be conceived.
Also, little is known about the rela-
tive damage that is done by hail,
water, and wind during a storm.
The research phase need not be
completed, however, before modifica-
tion experiments can be thought of.
On the contrary, the problem should
be considered as a field program in
experimental meteorology, where a
well-conceived experiment with hail
clouds is carried out with the poten-
tial of observing a cause-and-effect
relationship. Some hail clouds are
more suited to such an experiment
than others; for example, hail clouds
growing from the rear edge should
have a basically simpler structure
than hail clouds that grow from the
leading edge. Such clouds are also
easier to observe, as they are not
usually obscured by an overhanging
anvil.
The National Hail Research Ex-
periment (NHRE) attempts to ac-
complish exactly this ba
research objectives and suppression
operations — namely, to use aircraft,
radar, and surface networks for a
thorough study of the hailstorm
simultaneously with a well-designed
aircraft seeding program to which the
storm's reaction is observable. The
latter program cannot be conducted
entirely without statistical control.
Hail Suppression: Soviet Union
Much information has been ob-
tained from the operational hail-
suppression experiments in the Soviet
Union, specifically in the Caucasus.
Several books have been published,
and exchange visits between Soviet,
American, and Canadian scientists
have taken place, with many fruitful
discussions, although it has not been
possible to obtain a clear appraisal
of the validity of the claims made
by Soviet scientists.
It appears that two major efforts
are under way in the Soviet Union
which differ basically in the means of
delivering the seeding agent into the
cloud. In one, guns and shells are
used; in the other, rockets. While the
guns have greater range and altitude
and deliver 100 to 200 grams of the
seeding agent (Agl or Pbln) by ex-
plosion of the "warhead," the rockets
can carry a larger amount of the
agent and deliver by burning a pyro-
technic mixture (3.2 kg). The rockets
are somewhat more versatile in de-
livery either on a ballistic curve
through the storm or vertically inside
the cloud when descending by para-
chute.
One of four current projects in
the Soviet Union is carried out
through the Academy of Sciences of
the Georgian S.S.R. in the Alazani
Valley of the Caucasus, with Kart-
sivadze as the chief scientist. Another
is conducted by the Hydromete-
orological Service in Moldavia by
Gaivoronskii and others. The third,
and largest, project seems to be
conducted by the High Altitude In-
151
PART V — SEVERE STORMS
stitute of the Hydrometeorological
Service in Nalchick, under the di-
rection of Sulakvelidze. This proj-
ect consists of hail-suppression ex-
peditions in the northern Caucasus,
Azerbaidjan, and Armenia. The
fourth is also in the Georgian S.S.R.
and is under the direction of Lomi-
nadze. Rockets are used in the first
two projects; guns are used exclu-
sively in the last two. The Ministry
of Agriculture furnishes the hardware
and crews for the field projects.
Scientific Bases — All of these ef-
forts are based on the validity of the
relationship
N ( Ns )
RS = R
where Rs is the mean-volume hail-
stone radius after seeding,
Rn is the mean-volume hail-
stone radius without seed-
ing,
Nn is the hailstone concentra-
tion without seeding,
and Ns is the seeded hailstone con-
centration.
A physical justification for the
validity of this relationship was given
by Iribarne and dePena and con-
firmed more recently by List and
Lozowski. The most important find-
ing of this theoretical work is that
the water content of a hail cloud
becomes effectively depleted by a
small number of hailstones, of the
order of 10 per cubic meter, so that
even modest artificial increases of
their concentration by two orders of
magnitude can be expected to de-
crease their size sufficiently to prevent
damage. It is this recognition that
brings hail-suppression experiments
into the realm of physical realization
and economic benefit.
All experiments in the Soviet
Union seem to be designed in similar
fashion: hail forecast, radar analysis,
identification of the hail-spawning
area in the cloud, and delivery of the
seeding agent into the hail cloud.
Forecasting skill has been developed
to the degree that special experiments
can be carried out to prevent the
development of impending hail, while
others are conducted to stop hail al-
ready falling.
Reported Results — Soviet scien-
tists state that more than one million
hectares (3,900 square miles) were
protected in 1966. Hail damage in
the protected area was 3 to 5 times
smaller than in the unprotected area,
which means that the cost of pro-
tection amounts to barely 2 or 3
percent of the value of the crops
involved. For 1966, the total ex-
penditure for protection was 980,000
rubles, and the computed economic
effect was a saving of 24 million
rubles.
Gaivoronskii and others have also
reported on hail-suppression experi-
ments in Moldavia, near the Bulgar-
ian eastern border. These experi-
ments utilize "Oblaka" rockets, a
type that has a caliber of 125 milli-
meters, weighs 33 kilograms, holds
3,200 grams of PbL- as a pyrotechnic
mixture, and delivers a total of 3 x 1016
nuclei at -10° centigrade. Maximum
range and height are 12 and 9.5
kilometers, respectively. The authors
state that, in 1967, only 551 hectares
out of 100,000 hectares of crop were
damaged compared with 4,784 hec-
tares in the control area. A similar
effort with rockets is being carried
out by Kartsivadze.
Evaluation — It appears from the
literature that the work in the Soviet
Union is already past the research
phase and well into the operational
stage. As tests in the research phase
were not randomized, however, a firm
statistical significance has not been
established. It is possible that the
discovery by Changnon of the oc-
currence of individual, short hail-
streaks rather than long hailswaths
may invalidate some of the conclu-
sions made by the experimenters.
Thus, a hailstreak may terminate by
itself, rather than as a result of the
seeding action, before reaching the
boundary of the protected area, and
since there are no means of knowing
this beforehand such a case is counted
as a positive seeding result. These
conditions clearly point to the great
complexity of designing a randomized
experiment that would yield a unique
result in a relatively short time.
There can be little doubt that the
basic approach of the Russian sci-
entists, to treat each hailstorm as an
individual case, is appealing; at the
least, it eliminates the great uncer-
tainty of the diffusional process from
surface generators to the storm.
Hail Suppression: Switzerland
The GROSSVERSUCH III hail-sup-
pression experiment was conducted in
Switzerland from 1957 to 1963 in the
Canton Ticino. The experimental
area appears to have been larger than
the canton, since generators and rain-
gauges were distributed over roughly
10,000 square kilometers, but the
size of the area instrumented with
24 surface Agl generators (type un-
specified) was only a minor part of
about 4,000 square kilometers, one-
half of which were in Italy.
After many years of careful
freezing-nuclei measurements in
and downwind from Agl generator
sources it was concluded that, in
order to be effective, seeding from
the ground must be concentrated in
the regions and at the moment in
which storms form. It would appear,
however, that the analysis should
only be performed for the area coin-
ciding with the generator network.
Since this was not done, conclusions
reached in the experiment — to the
effect that "there is little doubt that
seeding has been very effective in in-
creasing the number of hail days" —
seem to be not entirely valid.
Hail Suppression: France
French efforts in operational hail
suppression are also continuing. Des-
152
HAII.
sens gives a 22.6 percent decrease of
hail falls as an average over the eight-
year period since the experiment be-
gan. The French scientists are using
surface Agl-acetone generators, of
which 240 are distributed over 70,000
square kilometers. The generators are
lighted 6V2 hours before the expected
outbreak of hailstorm activity in or-
der to load the air sufficiently with
good freezing nuclei, which may not
normally be possible.
The operations in Switzerland
(GROSSVERSUCH III) can be re-
lated to those in France in regard to
the density of the generator network.
The results for GROSSVERSUCH III
show an increase of the number of
days of hail (and an increase of rain
amount per seeded day), while Des-
sens reports a decrease in hail dam-
age. Of course, "days of hail" and
"hail damage" are two parameters
that need not be directly proportional.
Hail Suppression: Kenya
Final results are available for the
hail-suppression experiment carried
out from 1963 to 1967 in Kericho,
Kenya. It was based on the firing
of Italian antihail rockets from 13
firing positions within the Kitumbe
Estate. In 1968 the rocket network
was expanded to neighboring estates
to a total of more than 30 stations.
The rockets contain 800 grams of
TNT and no Agl; their burst occurs
at 2,000 to 2,400 meters above
ground or at about the +2° cen-
tigrade level. Rocket-firing begins
when hail starts falling and continues
until hail stops. In Kitumbe nearly
5,000 rockets were fired during 60
hail storms.
Because of the consistency of the
reduction of damage on Kitumbe dur-
ing both periods, it seems unlikely
that this was due to chance. (See
Figure V-12) Five mechanisms have
been suggested to explain why the
experiment should work: (a) cavita-
tion, (b) shock-induced freezing, (c)
freezing due to adiabatic expansion,
(d) introduction of ice nuclei, and
(e) introduction of hygroscopic nuclei.
Continuing Experimentation — Pre-
liminary results have been obtained
from continued experiments over tea
estates in Kericho. Seeding was done
at cloud base with pyrotechnic de-
vices dispersing between 6 and 30
grams of Agl per minute; 247 seed-
ing flights were carried out on 225
operational days. In the first season,
58 hail reports from within the tea
groves were obtained from 670
seeded cells, against a historical
background of 360 hail reports from
686 nonseeded cells. Damage per hail
instance was 2,929 pounds with seed-
ing and 7,130 pounds without seed-
ing. The great frequency of storms
seems to make this area an excellent
natural laboratory.
Hail Suppression: Italy
The effort in Italy proceeds along
two avenues. The first approach is
scientific in character and entails a
study of the hail phenomenon rather
than of hail prevention. The project
is carried out by the Institute for
Atmospheric Physics of the National
Research Council. The second ap-
proach has been developed by farmer
associations and the Ministry of
Agriculture and Forests. The largest
effort is that of exploding rockets
inside the clouds when the hailstorm
is overhead. The rockets carry 800
grams of TNT to altitudes of 1,000,
1,500, or 2,000 meters. In 1968,
96,000 of these rockets were fired
in Italy. Plans are being made
through the National Bureau of Elec-
trical Energy for a project employing
ground-based silver iodide burners of
the type used by Dessens in France.
Hail Suppression: United States
In the United States, plans for a
National Hail Suppression Field Test
proceed slowly, while theoretical and
applied research on the structure of
hailstorms and the hailstone mech-
anism progresses more rapidly. Proj-
ect HAILSWATH, a loosely coordi-
nated field experiment, was organized
in the summer of 1966 in Rapid City,
South Dakota. Twenty-three institu-
tions participated in this endeavor,
whose outstanding purpose was to
explore the feasibility of a large joint
operation involving, at times, as
many as 12 aircraft. Hailstorms were
seeded with dry ice and silver iodide
according to a target-control area
approach on 10 experimental days,
but the results lack statistical sig-
nificance.
A review of various hail-suppres-
sion projects in the United States
makes it apparent that American
hail-suppression activities can hardly
be called successful.
Figure V-12 — HAIL SUPPRESSION AT KERICHO, KENYA
July 63
Sept 65
Control
to
to
Period
Aug 65
Sept 67
All estates
without
rockets
20
22
24
Kitumbe
18
3
4
Other
rocket firing
estates
24
22
11
The table shows the decrease in the average loss per hailstorm in kilograms per
hectare at Kitumbe estate compared with other estates in the nearby area.
153
PART V — SEVERE STORMS
Current Status of Hail Prevention
Hail losses in the United States,
including damage to property and
agricultural crops, have been esti-
mated at $200 million to $300 million
annually. While damage from hail-
storms can occur in nearly every
state, major hail losses are concen-
trated in a belt extending from west-
ern Texas through the High Plains
into Alberta, Canada.
Most property owners respond to
the hail risk by buying insurance,
since damages by hail are typically
covered in a homeowner's compre-
hensive policy. However, insurance
coverage is less satisfactory for agri-
cultural crops, because of the high
premiums required in regions of high
hail hazard. Crop hail insurance pre-
miums in the Great Plains can range
up to 22 percent for a standard policy.
During a period of crop surpluses,
it may be debatable whether crop
losses from hail justify any substan-
tial research effort. However, from
the point of view of the effects of
hailstorms on society, and consider-
ing the trauma of a hailstorm loss
and the fact that destruction of prop-
erty by hail is a net economic loss,
investigation of artificial hail preven-
tion deserves attention.
In regions of high hail hazard, it
appears likely that an ability to re-
duce hail damage by as little as 5 or
10 percent would provide a net eco-
nomic benefit. It is anticipated that
hail reduction of 50 to 75 percent
should be possible, with a resulting
higher net economic benefit.
Data Base: Large-Scale Field
Experiments
Attempts to prevent hail by cloud
seeding were initiated shortly after
the early experiments of Schaefer and
Langmuir in the late 1940's. The
projects were based mostly on the
concept of reducing hailstone size
through increases in the number of
hailstone embryos. Silver iodide was
the most common seeding agent and
was frequently released from net-
works of generators on the ground.
The early projects in this country
suffered from numerous handicaps,
including a lack of knowledge of
cloud processes and of resources for
any significant evaluation studies.
The early hail-suppression projects
in the United States were conducted
for commercial sponsors and em-
ployed little or no statistical design.
Some randomized experiments using
ground-based generators were car-
ried out in Argentina, Switzerland,
and Germany. They yielded evidence
that silver iodide could affect hail-
storms, but that the effect could be
unfavorable as well as favorable.
Throughout the 1960's, under-
standing of hail-formation processes
was advanced through a number of
extensive observational programs of
hailstorms in the United States and
abroad. The work carried out in
the Soviet Union during this period
is especially noteworthy, but observa-
tional programs carried out in north-
east Colorado also deserve mention.
Improved understanding of hail
growth processes led to more sophis-
ticated systems for treatment. Seed-
ing was increasingly carried out from
aircraft and represented attempts to
influence specific parts of a hail-
bearing cloud rather than attempts
to increase ice-nucleus concentrations
throughout large volumes. This lo-
calization of the seeding treatment
reached its apex in the development
in the Soviet Union of a system to
introduce seeding agents into special
regions within a cloud by means of
artillery shells.
There is increasing evidence that
the seeding treatment used through-
out the 1960's has been effective in
eliminating hail from certain storms
and reducing hail damage in other
instances. Review of the evidence
from a number of hail-prevention
projects leads to the conclusion that
the projects were successful in some
instances. More recent results indi-
cate substantial success in hail pre-
vention in the United States, East
Africa, France, and the Soviet Union.
Indeed, a leading Soviet scientist is
quoted as saying that "the problem
of hail control is successfully solved."
Mathematical Modeling
During the past five years, sub-
stantial advances have occurred in
mathematical models of cumulus
clouds. An ability to create realistic
mathematical models of hailstorms
would provide the basis for a better
understanding of hail-formation proc-
esses and mechanisms for hail pre-
vention.
Initial cloud-modeling attempts
utilized relatively simple one-dimen-
sional steady-state models. These
simple models were helpful as fore-
runners of more complex models
which now simulate realistically the
life history of a large rain shower.
In addition to modeling the dy-
namics and life history of the large
cumulonimbus clouds, greater atten-
tion has been given to the mathemati-
cal simulation of individual hailstone
growth. Early efforts at development
of a mathematical formulation of
hailstone growth are being continued.
More recent work has given greater
insight into the hailstone growth
process, and shows that the primary
region of hailstone growth appears to
be in the higher and colder parts
the hail-bearing clouds. (See Figure
V-13) This information, derived
from the mathematical analysis, is
consistent with field observations. It
is of particular importance since it
154
HAIL
implies a basis for success in hail
prevention by cloud seeding through
the mechanism of drying out the re-
gion of the cloud in which hailstones
form.
Although unresolved problems re-
main concerning the position of hail
growth with respect to the updraft
maximum and the liquid-water con-
centrations in hail-growth regions,
a picture is beginning to emerge of
a physically reasonable system for
hail growth and hail prevention that
is consistent with observations ob-
tained from field projects.
Prevailing Scientific Controversy
There is no general agreement on
the effectiveness of hail-prevention
techniques. Skepticism concerning the
claims of success in the Soviet Union
and concerning the reality of ap-
parent reductions in hail damage on
hail-suppression projects in this coun-
try loomed large in the development
of current plans for hailstorm re-
search in the United States. This is
illustrated by the following extract
from a planning document for the
National Hail Research Experiment
(NHRE):
. . . This document i
tirely concerned with a discussion
of the need to complete success-
fully a Hail Suppression Test Pro-
gram, since it appears to us that
a National Hail Modification Pro-
gram is now premature. We must
first determine if hailstorms can
indeed be modified, and then learn
if it is worth the effort.
This point of view (that so little
is known about hailstorms that the
primary hail research effort should be
so directed) is in conflict with the
point of view that current knowledge
Figure V-13 — A MIDWEST THUNDERSTORM
Temp Height
(°C) (kml
-55
-50-
•10
-40
-30--8
-20
12
10
20-.
-10-
0--40
-37
The figure shows a single, mature convective storm of the midwestern U.S. which
is apt to produce hailstones. A temperature and height scale are along the lefthand
margin. Note the base of the cloud at 3.7 kilometers. The vertical wind speed
profile is plotted over the cloud and indicates a maximum wind speed of 19 meters
per second near the middle level of the cloud. If the maximum speed of the updraft
exceeds the terminal velocity of the largest stable droplet, an accumulation zone
of supercooled water forms because of the chain-reaction mechanism triggered by
droplet breakup. The heavy line in the center section of the cloud is the 35-decibel
contour as seen by radar. The accumulation zone is within this area. It is this area
into which seeding material should be placed to be effective.
155
PART V — SEVERE STORMS
provides a valid basis for initiating
programs for application of current
technology to hail prevention.
Requirements for Scientific
Activity
Instrumentation — Current hail-re-
search plans call for a substantial
effort to develop sophisticated instru-
mentation to attempt to obtain the
detailed life history of hail-bearing
clouds. This is considered necessary
to create a complete physical model
of such storms. Development of the
instrumentation for this task will
require a major effort. The NHRE
five-year program involves large ex-
penditures for radars, specialized air-
craft, and large numbers of field
personnel.
The instrumentation and equip-
ment required for a more modest
effort at suppressing hail in a pre-
designated target area would be less.
Such an approach could provide a
means of testing various hail-suppres-
sion techniques, would provide a
basis for attaining knowledge to an-
swer extant scientific questions, and
would also partially satisfy the view
that attempts should be made to
apply current technology without fur-
ther delay for scientific investigation,
which should continue concurrently.
Applied Technology — Develop-
ment of hail-suppression technology
involves not only basic research, as
is being planned under the current
NHRE effort, but also efforts to
apply the technology. Needs for
basic research on hail appear to be
covered adequately in present plans
for NHRE. However, efforts in the
development and application of hail-
suppression technology are badly
needed.
An advantage of having several
applications projects under way si-
multaneously is that they can provide
additional testing opportunities and
opportunities for learning. An essen-
tial requirement for optimum learning
is to have a number of untreated
cases, randomly selected, reserved as
"control" cases. In several locations,
local groups primarily concerned
with applications and benefits from
weather modification projects have
agreed voluntarily to forgo treat-
ment of a limited number of storm
situations to provide such control
cases. This willingness sets the stage
for an opportunity for increased
learning.
However, local groups that have
organized to apply hail-suppression
technology have sometimes expressed
the opinion that the scientific com-
munity is more interested in perpetual
programs of research than it is in ap-
plication. Such groups may be in-
clined to proceed on their own with
premature operational programs that
involve not only improper techniques
but also foreclose future opportuni-
ties for associated research efforts.
It is, therefore, rather urgent that
steps be taken to develop mechanisms
for cooperation with such local
groups while the opportunity to re-
serve some untreated control cases
still exists. If local groups begin hail-
suppression programs from which
they believe benefits are being ob-
tained, the opportunity for coopera-
tion and continued learning will
disappear, since pressures will exist
for treatment of all cases.
Approximate Time-Scale — If the
present NHRE program begins its
activities on schedule in 1972, it
should produce useful inputs to hail-
suppression technology within ap-
proximately five years. In addition,
if steps are taken to work with local
groups, useful inputs to hail-suppres-
sion technology can also be antici-
pated within three to five years of
the start of such programs.
Considering the time-scale for both
basic research and applications pro-
grams, it should be possible to obtain
adequate knowledge to carry out hail-
reduction efforts economically and
routinely by the end of this decade.
156
4. LIGHTNING
Basic Processes of Lightning
About 2,000 thunderstorms are in
progress over the whole earth at any
given time. These storms produce a
total of about 1,000 cloud-to-ground
and 500 intracloud lightning dis-
charges each second. It follows that
there are over S million lightning
discharges each day to earth, and
about 5 times as many discharges
within the clouds.
Lightning is essentially a long
electric spark. (See Figure V-14) The
total electrical power dissipated by
worldwide cloud-to-ground lightning
is roughly equal to the total annual
power consumption of the United
States, about 500 billion watts. On
the other hand, the energy from a
single lightning flash to ground is
only sufficient to light a 60-watt bulb
for a few months. It is the high
worldwide rate of lightning flashing
that provides the high power levels.
The electrical energy that generates
lightning is transformed to sound
energy (thunder), electromagnetic
energy (including light and radio
waves), and heat during the discharge
process. The radio waves emitted
by the hundreds of lightning dis-
charges per second provide a world-
wide noise background. The level at
which many communications systems
can operate is limited by this back-
ground noise level. The radio waves
emitted by a single close (say, closer
than one mile) lightning discharge
can also cause malfunction of sensi-
tive electronic systems (particularly
solid-state systems) such as are used
in modern guided missiles.
The heat generated by the lightning
channel sets forest fires, ignites flam-
mable materials, and can be a cause
of individual death. Of the over 8
million discharges that hit the earth
daily, very few cause damage. For
example, most lightning to wooded
areas does not cause forest fires.
Still, there are about 10,000 forest
fires a year in the United States at-
tributable to lightning; and about
2,000 rural structures, roughly half
of which are barns, are destroyed
by lightning-induced fires each year.
Lightning strikes about 500 U.S.
commercial airliners per year. Most
Figure V-14 — LIGHTNING
(1) This photograph shows a normal cloud-to-ground lightning flash near Mount
San Salvatore. Lugano, Switzerland. Note how the streamers from the main lightning
strokes branch downward. (2) In this photograph, a tall tower on Mount San Salva-
tore has triggered a lightning flash. Note how the streamers branch upward, indicat-
ing a reverse situation from the normal lightning flash.
157
PART V — SEVERE STORMS
strikes produce little if any damage,
the lightning being confined to the
plane's metal skin. Sometimes, how-
ever, potentially serious structural
damage, such as the melting of large
holes, does occur. There have been
two cases of the total destruction of
aircraft which the Federal Aviation
Administration has attributed to igni-
tion of the aircrafts' fuel by lightning.
The most recent case was that of a
Pan American Boeing 707, which
exploded over Elkton, Maryland, in
December 1963 after being hit several
times by lightning.
In addition to the radio waves and
heating effect produced by lightning,
the direct electrical effects of light-
ning are often deleterious. They can,
for example, result in the disruption
of electrical power, as is often the
case when lightning strikes a power-
transmission line or a power station.
Direct electrical effects can also result
in malfunction or destruction of criti-
cal electronic equipment in aircraft
and missiles. A spectacular example
of the foregoing was the lightning-
induced malfunction of the primary
guidance system of the Apollo 12
moon vehicle. Further, individual
deaths from lightning, about 200 per
year in the United States, are pri-
marily due to electrocution.
Control of Lightning
What can we do to control light-
ning? Are there possible harmful
consequences of such control? Let us
look at the second question first and
attempt to answer it by two examples.
Suppose technology were advanced
enough that we could stop lightning
from occurring. What would the
result be to forests and the at-
mosphere?
1. If there were no lightning,
would the incidence and de-
structiveness of forest fires de-
crease? In many cases, forest
fires would be less common, but
those that did occur would be
more destructive. Lightning-
induced forest fires and the
forests have lived together in
some sort of equilibrium for a
a long time. (The oldest ar-
cheological evidence of light-
ning is dated at 500 million
years ago.) There is now some
evidence to indicate that fre-
quent forest fires will keep a
forest floor clean so that the
fires that do occur are small
and will not burn the trees.
Further, in some cases, rela-
tively clean forest floors may
be necessary for the germina-
tion of new trees. For example,
Sequoia seedlings can germi-
nate in ashes but are suppressed
under a thick layer of needles
such as would cover an un-
hurried forest floor. Thus, it
is not obvious that blind control
of forest fires is desirable.
2. If the frequency of lightning
were diminished, would there
be an effect on the atmosphere?
Nobody knows. Lightning cur-
rents and other electrical cur-
rents flowing in the atmosphere
during thunderstorms deliver
an electrical charge to the earth.
An approximately equal charge
(a balancing charge) is thought
to be carried from the earth to
the ionosphere in areas of fair
weather by the ambient fair-
weather electric field between
the earth and the ionosphere.
Changing the lightning fre-
quency might upset this charge-
transfer balance with a result-
ant effect on the fair-weather
field. The change in the fair-
weather field might trigger
further reactions.
The study of the effects of light-
ning on the environment is in its
infancy. The control of lightning is
not necessarily desirable unless the
full consequences of that control are
evaluated.
Now, let us look at lightning con-
trol. When "control" is mentioned
it is reasonable to think either of (a)
stopping lightning or (b) harnessing
its power. To harness appreciable
power from lightning would require
a worldwide network which could
tap energy from a reasonable fraction
of the world's total discharges. Even
if science were to devise an efficient
way to tap energy from a lightning
stroke (which it has not yet done),
the construction and maintenance of
some sort of worldwide network ap-
pears at present to be impractical.
On the other hand, stopping lightning
from a given storm, or at least de-
creasing its frequency, is certainly a
practical goal, and some initial steps
in this direction have been taken.
For example, it has been experi-
mentally demonstrated, although not
to the satisfaction of everyone con-
cerned, that cloud seeding can some-
times decrease the number of light-
nings produced by a thundercloud.
Understanding of Lightning
A number of photographic, elec-
trical, spectroscopic, and acoustic
measurements have been made on
lightning. From these we have a
reasonably good idea of the energies,
currents, and charges involved in
lightning, of the electromagnetic
fields (radio waves, light, and so on)
generated, of the velocities of propa-
gation of the various luminous
"streamer" processes by which the
lightning discharge forms, and of
the temperature, pressure, and types
of particles comprising the discharge
channel. In short, we have available
both an observational description of
how lightning works (e.g., the dis-
charge is begun by a luminous leader
which is first seen at the cloud base
and moves toward ground in steps,
as shown in Figure V-15) and most
of the data needed for routine engi-
neering applications (e.g., power-line
design and lightning protection).
A good deal of what we know
about lightning has been determined
in the United States in the past fifteen
years. However, the total number of
U.S. researchers primarily studying
158
NFNG
Figure V-15 — THE INITIATION OF A LIGHTNING STROKE
WA WW//////////////,.
(Illustration Redrawn with Permission. BEK Technical Publications, Inc. Carnegie. Pa)
The drawing shows the initiation of a stepped-leader from a cloud base. The time
involved is about 50 millionths of a second. As the downward-moving leader gets
close to the ground, upward-moving discharges meet it. A return stroke then propa-
gates from the ground to the cloud. The time for the return stroke propagation is
about 100 millionths of a second. Propagation is continuous until the charges are
dissipated.
lightning at any given time during
this period has been only about ten,
of which perhaps half have contrib-
uted to our understanding of light-
ning. As an example of the general
lack of scientific interest in lightning
phenomena, the first technical book
on lightning was not published until
1969.
While we have available a number
of observational "facts" about light-
ning, we do not understand lightning
in detail. Areas of particular igno-
rance are: (a) the initiation of light-
ning in the cloud and (b) propaga-
tion of lightning from cloud to
ground. Unfortunately, these are just
the areas in which a detailed under-
standing is essential if lightning con-
trol is to be practiced.
It is important to know what we
mean by a "detailed understanding."
A "detailed understanding" implies a
mathematical description or model of
the lightning behavior. The mathe-
matical model is adequate when it can
predict the observed properties of
lightning. The mathematical model
can then be used to determine the
effects on the lightning of altering
various parameters of the model.
For the case of lightning initiation,
these parameters might be the am-
bient temperature, ambient electric
field, number of water drops per
unit volume, etc. The predictions of
the mathematical model must be
tested by experiments. The results
of these experiments can suggest
changes in the model or can verify
its validity. It follows that experi-
ment and theory must advance to-
gether to achieve a complete descrip-
tion of the lightning phenomenon.
The physics of lightning initiation
and propagation is exceedingly com-
plex. Some idea of its complexity can
be gauged by noting that the proc-
esses involved in electrical breakdown
between a rod and a flat plate in the
laboratory (an electric spark) are at
present only vaguely understood. It
appears that, despite about thirty
years of experimental work, a real
understanding of the laboratory spark
will not be available until a mathe-
matical description of the spark is
forthcoming. Only recently have
digital computers become available in
a sufficient size that a mathematical
solution to the spark problem is in
principle possible.
The Future
Significant progress in our detailed
understanding of lightning could
probably be made in the next ten to
fifteen years, although given the pres-
ent level of scientific activity and
ability in the lightning area, it is
unlikely that this will be the case.
Lightning research has been neither
glamorous enough nor quantitative
enough to attract the attention of
many good graduate students or
senior scientists. Several excellent ex-
perimentalists are presently working
in the lightning area, and their work
needs to be continued and enlarged.
More important to the goal of de-
tailed understanding of lightning,
however, is the need for mathemati-
cally oriented scientists to become
involved in the problems of lightning
initiation and propagation. The
mathematically oriented scientists and
the experimentalists should work
closely together in both the construc-
tion of suitable mathematical models
and in the planning and analysis of
experiments.
In studying lightning, the time-
scale on which meaningful results
can be expected is relatively long.
From an experimental point of view,
the necessity of staying in a given
location for a long enough time to
observe enough lightning to be able
to compile statistically significant re-
sults determines the time-scale of any
particular lightning research pro-
gram — generally, several years. The
mathematical approach to lightning is
exceedingly complex and thus must
also take place on a time-scale of
several years. With a coordinated
work force of perhaps five senior
159
PART V — SEVERE STORMS
theoreticians and fifteen senior ex-
perimentalists (assuming, of course,
that these researchers are equipped
with the necessary skills), one might
expect significant progress in our
detailed understanding of lightning
in the next ten to fifteen years. There
is certainly no assurance of success
in any lightning research. It is clear,
however, that a successful effort to
understand lightning must be a long-
term effort.
Reduction of Lightning Damage by Cloud Seeding
Lightning is an important cause of
forest fires throughout the world and
especially in North America. In an
average year, about 10,000 forest fires
are ignited by lightning; in a severe
season, the number may rise to
15,000. The problem is particularly
acute in the western states, where
lightning ignites over 70 percent of
the forest fires. Here, hundreds of
fires may be ignited in a single day,
many of them in remote and inac-
cessible regions. These peaks in oc-
currence, along with existing heavy
fire loads, tax fire-suppression agen-
cies beyond reasonable limits of man-
power and equipment. Fire-suppres-
sion costs can be very high; direct
costs may approach $100 million per
year while losses of commercial tim-
ber, watersheds, and other forest
resources may be several times this
amount. In addition to loss of human
lives, lightning fires constitute a
growing threat to homes, businesses,
and recreational areas.
Potential Modification Techniques
What steps could be taken in
weather modification to alleviate the
lightning-fire problem? The most ob-
vious is to reduce the number of
cloud-to-ground discharges, particu-
larly during periods of high fire
danger. Those characteristics of dis-
charges most likely to cause forest-
fire ignition might be selectively mod-
ified to decrease their fire-starting
potential. Also, the amount of rain
preceding or accompanying lightning
could be increased in order to wet
forest fuels and thus decrease the
potential for fire ignition and spread.
A Seeding Experiment — The large
losses in natural resources each year
caused by lightning-ignited forest
fires has prompted the Forest Service
of the U.S. Department of Agricul-
ture to perform a series of experi-
ments in the northern Rocky Moun-
tains which are aimed at reducing
fire-starting lightning strokes by
massively seeding "dry" thunder-
storms over the national forests.
Following is a summary of results of
the studies of lightning-fire ignition
and lightning modification.
The first systematic program of
lightning modification was conducted
in western Montana in the summers
of 1060 and 1961. This two-year
pilot experiment was designed to test
the effect of seeding on lightning
frequency and to evaluate lightning-
counting and cloud-seeding methods
in mountainous areas. Some 38 per-
cent fewer ground discharges were
recorded on seed days than on days
when clouds were not seeded. Intra-
cloud and total lightning were less
by 8 and 21 percent, respectively,
on seed days during the two-year
period. Analysis of these data by a
statistical test showed that, if seeding
had no effect, differences of this
magnitude would occur about one
in four. Also, the experiment con-
firmed the need to develop a contin-
uous lightning-recording system that
could resolve the small-scale details
of individual lightning discharges.
Subsequently, a continuous lightning-
recording system and improved cloud-
seeding generators were developed.
Building a Data Base
A new lightning-modification ex-
periment was begun in 1965, with
the first phase to last for three sum-
mer seasons. The objectives were
to gain additional information on
the frequency and characteristics of
lightning from mountain thunder-
storms and to determine if there is
a significant difference in the occur-
rence and character of lightning from
seeded and unseeded storms. It was
not designed to confirm or reject a
single mechanism by which lightning
is modified by seeding. Rather, a
primary objective was to build a
body of observations of lightning
from both seeded and unseeded
storms and to use these data to build
appropriate hypotheses and models
for testing in future experiments.
Appropriate statistical tests were in-
cluded in the design of the experi-
ments as a basis for evaluating dif-
ferences attributable to treatment.
Analysis of data on the basis of
the life cycle of individual thunder-
storms occurring in 1965-67 (14 no
seed, 12 seeded storms) gave the
following results at the given level of
significance for two-tailed tests:
1. Sixty-six percent fewer cloud-
to-ground discharges, 50 per-
cent fewer intracloud dis-
charges, and 54 percent less
total storm lightning occurred
during seeded storms than dur-
ing the unseeded storms.
2. The maximum cloud-to-ground
flash rate was less for seeded
storms. Over a 5-minute inter-
val, the maximum rate averaged
8.8 for unseeded storms and
5.0 for seeded storms; for 15-
minute intervals, the maximum
rate for unseeded storms aver-
aged 17.7 as against 9.1 for
seeded storms.
160
3. There was no difference in the
average number of return
strokes per discrete discharge
(4.1 unseeded vs. 4.0 seeded).
The average duration of dis-
crete discharges (period be-
tween first and last return
stroke) decreased from 235 mil-
liseconds for unseeded storms
to 182 milliseconds for seeded
storms.
5. The average duration of con-
tinuing current in hybrid dis-
charges decreased from 187
milliseconds for unseeded
storms to 115 milliseconds for
seeded storms.
Inferences
The results from the seeding ex-
periments to date strongly suggest
that lightning frequency and char-
acteristics are modified by massive
seeding with silver iodide freezing
nuclei. While the physical mechanism
by which massive seeding modifies
lightning activity is not fully under-
stood, there is evidence that the
basic charging processes are altered
by the seeding. Further, it has been
established on the basis of direct
measurements that hybrid discharges
(lightning strokes that contain a con-
tinuing current) may be responsible
for most lightning-caused forest fires.
Thus, a substantial reduction in the
duration of the continuing-current
portion of the hybrid discharge may
have a large effect on the ability of
an individual discharge to ignite fuels
or to cause substantial damage. This
change in the nature of the discharge
may be more important than a change
in the total amount of lightning that
is produced by the storms.
161
PART VI
PRECIPITATION AND
REGIONAL WEATHER
PHENOMENA
1. DROUGHT
The Causes and Nature of Drought and its Prediction
Drought is one of the manifesta-
tions of the prevailing wind patterns
(the general circulation). A few spe-
cial remarks may clarify this mani-
festation, and suggest further work
necessary to understand and predict
droughts.
Virtually all large-scale droughts
(like the Dust Bowl spells of the
1930's or the 1962-66 New England
drought) are associated with slow and
prevailing subsiding motions of air
masses emanating from continental
source regions. Since the air usually
starts out dry, and the relative hu-
midity declines as the air descends,
cloud formation is inhibited — or, if
clouds are formed, they are soon
dissipated.
The atmospheric circulations that
lead to this subsidence are certain
"centers of action," like the Bermuda
High, which are linked to the plan-
etary waves of the upper-level wester-
lies. If these centers are displaced
from their normal positions or are
abnormally well developed, they of-
ten introduce anomalously moist or
dry air masses into certain regions
of the temperate latitudes. More im-
portant, these long waves interact
with the cyclones along the polar
front in such a way as to form and
steer their course into or away from
certain areas. In the areas relatively
invulnerable to cyclones, the air de-
scends, and if this process repeats
time after time, a deficiency of rain-
fall leading to drought may occur.
In other areas where moist air is
frequently forced to ascend, heavy
rains occur. Therefore, drought in
one area is usually associated with
abundant precipitation elsewhere.
For example, precipitation was heavy
over the Central Plains during the
1962-66 drought in northeastern
United States.
After drought has been established
in an area, it seems to have a tend-
ency to persist and expand into ad-
jacent areas. Although little is known
about the physical mechanisms in-
volved in this expansion and per-
sistence, some circumstantial evi-
dence suggests that numerous
"feedback" processes are set in mo-
tion which aggravate the situation.
Among these are large-scale inter-
actions between ocean and atmos-
phere in which variations in ocean-
surface temperature are produced by
abnormal wind systems, and these in
turn encourage further development
of the same type of abnormal circu-
lation. Then again, if an area such
as the Central Plains is subject to
dryness and heat in spring, the
parched soil appears to influence sub-
sequent air circulation and rainfall
in a drought-extending sense.
Finally, it should be pointed out
that some of the most extensive
droughts, like those of the 1930's
Dust Bowl era, require compatibly
placed centers of action over both
the Atlantic and Pacific oceans.
In view of the immense scale and
complexity of drought-producing sys-
tems, it is difficult for man to devise
methods of eliminating or ameliorat-
ing them. However, given global
data of the extent described previ-
ously, and the teamwork of oceanog-
raphers, meteorologists, and soil
scientists, it should be possible to
understand the interaction of con-
tinent, ocean, and atmosphere suf-
ficiently so that reasonably accurate
estimates of the beginnings and end-
ings of droughts are possible.
Ability to predict droughts would
be of tremendous planning value.
Unfortunately, encouragement for
drought research comes only after a
period of dryness has about run its
course, because the return of normal
or abundant precipitation quickly
changes priorities to more urgent
matters. Without continuing in-
depth drought studies, humanity will
always be unprepared to cope with
the economic dislocations induced by
unpredictable long dry spells.
It has long been known that the
general circulation of the atmosphere
is such that alternating latitude belts
of wetness and dryness tend to domi-
nate the world system of climates.
(See Figure VI-1) In connection with
droughts, the important belts are:
1. The equatorial belt of wetness
associated with ascending cur-
rents in the zone where the
trade winds from the southern
and the northern hemisphere
meet;
2. The subtropical belt of dryness
associated with descending air
motions in the so-called sub-
tropical anticyclones;
3. The mid-latitude belt of wetness
associated with traveling de-
pressions and storms that de-
velop in the zone of transition
between warm and cold air
masses — i.e., the "polar front."
While the equatorial belt of wet-
ness is more or less continuous around
the world, the subtropical belt of dry-
ness is disrupted by monsoon-like
winds in the warm seasons and by
polar-front disturbances in the cold
season. As a result, rainfall is gen-
erally adequate along subtropical east
165
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
Figure VI-1 — ANNUAL WORLDWIDE PRECIPITATION
I Over 80 inches annual mean rainfall
I j\ I I -Mi 4I.I In SO in hi",
[^] From 10 to 40 inches
j Under 10 inches
The map shows annual precipitation over the world compiled from land-station data
and some ship and island observations. Isopleths over the ocean areas, which
show large "dry" patches off western continental coastlines, are best guesses.
coasts (e.g., Florida), while dryness
typically prevails along subtropical
west coasts (e.g., southern California)
and in adjacent continents. Finally,
the mid-latitude belt of wetness will
be disrupted where mountain ranges
(e.g., the Rocky Mountains) provide
shelter against rain-bearing winds
from nearby oceans.
Between the semi-permanent cli-
matic patterns, which do not change
perceptibly, and the rather lively
short-term patterns associated with
traveling disturbances and storms,
there exist regimes of long-lived
anomalies superimposed on the gen-
eral circulation. These anomalies are
quasi-stationary or move very slowly,
and their duration and intensity may
vary within wide limits. Anomalies of
this kind are always present, and
when their duration and intensity ex-
ceed certain limits of dryness, they
become recognized as droughts. Most
national weather services have estab-
lished definitions of drought; al-
though these are useful for record-
keeping, administrative actions, and
such, they do not reflect scientific
principles. In the following, the word
drought will be used in the meaning
of an extensive period of excessive
dryness.
Research Findings
There is some indication that cer-
tain time-lag relationships exist. For
example, Namias found that many
summer droughts in the United States
appear to be associated with changes
in the upper atmosphere that begin
to develop in the foregoing spring.
There is a need here for more research
to determine whether reliable two-
way statistical relationships exist and
are applicable to independent sets of
data; if this should prove to be so,
techniques for predicting the onset of
individual droughts might be devel-
oped.
166
DROUGHT
The factors that determine the dur-
ation of droughts have not been well
explored and no predictive capability
exists. The droughts that have re-
ceived most attention are those that
have affected agricultural operations
— i.e., late spring and summer
droughts. Some of these have been
unable to survive the hardships of the
winter following, but others have
shown a tendency to recur the next
spring or summer, and these pro-
longed droughts are of great interest
economically as well as scientifically.
There is evidence to indicate that
drought-producing systems tend to
develop in families (rather than as in-
dividuals), though each member may
not qualify as a drought according
to official definitions. For example,
Namias found that drought-producing
anticyclones over the agricultural
heartland of North America have
companion anticyclones on the Pacific
as well as on the Atlantic. Drought-
producing anticyclones in the lower
atmosphere appear to be associated
with distortions of the flow patterns
through deep layers. Our knowledge
of these conditions is meager; much
firmer information could be provided
through special analyses of existing
data.
Although an official drought may
cover a relatively small region, the
associated atmospheric processes must
be studied in the context of the gen-
eral circulation of the atmosphere, in-
cluding the principal sources of heat
and moisture.
The Causes of Drought
The above-mentioned findings —
that drought-producing systems tend
to occur in families and that individ-
ual droughts may span one or more
annual cycles — are of considerable
scientific significance and hold out
hope of progress toward prediction.
These findings point toward the phy-
sical processes that create the large-
scale anomalies of which droughts are
manifestations. Since extraterrestrial
influences can safely be ruled out, it
is clear that the forces, or energy
sources, that bring about these anom-
alies must develop within the earth-
atmosphere system itself. Further-
more, since an individual drought in
middle and high latitudes (where the
annual variation is large) may outlast
an annual cycle, it is plausible that the
underlying energy sources are rooted
in the equatorial belt (where the an-
nual change is small).
Bjerknes has recently produced se-
lected analyses that indicate, with a
high degree of certainty, that the gen-
eral circulations of the atmosphere in
middle and high latitudes respond
readily and significantly to energy in-
puts resulting in variations in the
ocean-atmosphere interactions in low
latitudes. Of special importance is
the transfer of heat and moisture from
the oceans, and the freeing of latent
heat by condensation in the air. The
major site of interactions resulting in
varying inputs of energy is the equa-
torial belt from the west coast of
South America to beyond the date
line. Significant impulses can also be
traced to the Humboldt Current, the
Indian Ocean, and other areas.
Bjerknes found that the upwellings
of cool water, resulting from the vary-
ing convergence of the trade winds,
undergo changes that may be large at
times, and these affect the rate at
which energy is supplied to the atmos-
phere in the equatorial belt. These in-
puts are, in turn, exported via upper
air currents as various forms of
energy to the mid-latitude belt, where
they bring about distortions of the
flow patterns, dislocations of the
storm tracks, and regional anomalies
of different kinds. Of particular in-
terest in connection with droughts is
the tendency for more or less sta-
tionary offshoots from the subtropical
belt of dryness to disrupt the mid-
latitude belt of wetness. Bjerknes'
findings are of great interest and raise
hopes for progress in long-range pre-
diction and other applied areas.
Research Aspects — It is clear from
the foregoing discussion that our
knowledge of drought is fragmentary
and that much work remain
done before adequate descriptions of
individual or typical droughts can be
provided. An individual drought must
be recognized and described as a
member of a family of anomalies, and
its characteristics must be related to
the evolution of these anomalies. Un-
doubtedly, such descriptive studies
will lead to greater insights into the
underlying general mechanisms as
well as the many local or regional
factors that determine the severity of
droughts. In the past, research on
droughts has been conducted on an
ad hoc basis, with emphasis on local
or regional conditions. A concerted
effort, making full use of available
data and data-processing facilities,
seems justified in terms of national re-
quirements as well as available talent.
Although the broad aspects of the
causes of droughts appear to be un-
derstandable on the basis of Bjerknes'
findings, much work remains to be
done to relate the evolution and the
characteristics of atmospheric anom-
alies to specific variations in the ap-
propriate ocean-atmosphere interac-
tions. Empirical studies should be
matched with construction of models
to simulate the behavior of the atmos-
phere in response to observed or in-
ferred ocean-atmosphere interactions.
It is clear that the research oppor-
tunities in this general area are highly
promising. Data are available to sup-
port analyses of many cases, with ex-
tensions to longer time-spans. The
present recognition of a need for im-
proved understanding of our environ-
ment and better management of our
natural resources is likely to stimu-
late application. The research is likely
to appeal to young talent in several
disciplines. And the research is likely
to provide important inputs to the co-
operative schemes of the International
Decade of Ocean Exploration and the
Global Atmospheric Research Pro-
gram.
167
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
The Prediction of Drought
The National Weather Service is-
sues monthly general forecasts of
large-scale patterns of temperature
and rainfall, and from such forecasts
the likelihood of onset of drought dur-
ing the month concerned may be in-
ferred in general terms. At the present
time, no specific techniques for pre-
dicting drought exist. It is possible
that a study of time-lag relationships
for large areas could provide useful
guidance. It is possible, too, that run-
ning analyses of the conditions within
the Pacific section of the equatorial
belt and related studies of the re-
sponses of the mid-latitude atmos-
phere would provide useful prediction
aids. Finally, the results of the above-
mentioned studies are likely to be
considerably sharpened through nu-
merical experiments with dynamical
simulation models.
168
2. PRECIPITATION MODIFICATION
Artificial Alteration of Natural Precipitation
The scientific basis of all efforts to
modify precipitation artificially rests
on manipulating the rates of reaction
of natural precipitation mechanisms
Our qualitative understanding of nat-
ural precipitation mechanisms is in
rather good shape. (See Figure VI-2)
But our knowledge of the quantitative
aspects of these processes is generally
quite poor. There are several reasons
for this state of affairs:
1. The process rate coefficients are
inadequately known.
2. Several of the processes are
competitive, so that small initial
differences may give one of
them an ever widening advan-
tage.
3. The initial and boundary condi-
tions are known to be important
but are poorly understood and
difficult to measure.
Figure VI-2 — PRECIPITATION PROCESSES
CONTINENTAL NUCLEI
WATER VAPOR
nucleation
condensation
ICE NUCLEI
WATER VAPOR
nucleation
deposition
MARITIME NUCLEI
WATER VAPOR
CIRRUS
SEEDING
NARROW CLOUD SPECTRA
slow broadening
by coalescence
heterogeneous
freezing
SECONDARY
ICE PARTICLES
SECONDARY
ICE PARTICLES
ICE CRYSTALS -
nucleation
condensation
BROAD CLOUD SPECTRA
vapor
deposition
i
SNOW CRYSTALS—-
clumping
SNOWFLAKES
heterogeneous
freezing ""
_ FROZEN DROPS J X
ICE PELLETS
coalescence
t
DRIZZLE
riming
clumping
SECONDARY
ICE PARTICLES
RIMED CRYSTALS
RIMED FLAKES
continued
coalescence
riming
t
GRAUPELS
heterogeneous
freezing
wet and dry
riming with
drops and
crystals
partial
melting
I
BRIGHT BAND
RAIN SLEET
(WARM)
GRAUPELS
HAIL
SNOW
GRAINS
melting
RAIN
RIMED FLAKES
SNOW PELLETS
GRAUPELS ]
*
^ partial
melting
I
BRIGHT BAND
continued
coalescence
SNOW
■ melting ■
GRAUPELS RAIN
SNOW PELLETS
SMALL HAIL
^ heterogeneous .
freezing
SLEET
RAIN
(WARM)
In this flow chart, the precipitation process is seen to begin with water vapor and
one of several different types of nuclei. Through various processes, the nuclei
obtain vapor and grow. The final form of the precipitation depends on the environ-
ment through which the precipitation falls. The various forms of precipitation that
are observed in nature are listed at the bottom of the chart. By tracing their path
upward through the chart, it is possible to determine the conditions necessary for
their production.
169
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
4. There are several feedback loops
whereby a change in the micro-
physical character of a cloud
parcel, as a result of precipita-
tion development, feeds back
into the energetics of the cloud
and thereby alters the boundary
conditions in which the precipi-
tation processes operate. These
feedback loops are largely unex-
plored. They range in scale from
the release of heat of phase
change, causing a small cloud
parcel to accelerate upward,
thereby increasing its conden-
sate load, to large-scale, long-
range effects whereby a major
change in the cloud system at
one point induces adjustments
in the atmosphere tens or hun-
dreds of cloud-diameters away.
Natural Nuclei and their Relation
to Weather Modification
Almost all U.S. efforts to change
precipitation through cloud seeding
(whether to increase, decrease, or re-
distribute either rain or snow) rest on
the observation that the normal be-
havior of a cloud can be altered
through the introduction of large
numbers of suitable nuclei.
There are two types of natural
nuclei, serving two different func-
tions, in natural clouds:
1. Cloud nuclei (small soluble par-
ticles of the order of 0.1 to 3
microns in diameter), which
serve as condensation centers
for liquid cloud droplets.
2. Ice nuclei (probably clay min-
erals about 1 micron in diam-
eter, although the exact nature
of these particles is still in ques-
tion), which serve as centers of
initiation of ice particles either
by freezing drops or directly
from the vapor.
Ice nuclei are necessary for snow
production. Snow generated aloft may
melt inside a cloud on its way to the
ground and land as rain. Rain may
also be initiated by a few specially
favorable cloud nuclei acting through
an all-liquid process.
The relative importance of the two
known precipitation mechanisms is
not fully worked out. However, it
appears that the all-liquid process is
more important in warmer seasons
and in maritime air masses, whereas
the ice-crystal mechanism is probably
more important in colder seasons and
in continental weather events.
The ice-crystal mechanism of pre-
cipitation development was the first
precipitation process proposed. It ap-
peared to explain most available ob-
servations until the late 1940's, when
meteorologists began to make meas-
urements inside clouds and to examine
them with radar. The all-liquid pre-
cipitation mechanism was essentially
unknown before about 1950; even to-
day its relative importance is not clear.
The common occurrence of super-
cooled clouds was taken as evidence
to show that concentrations of nat-
ural ice nuclei were often insufficient
for effective precipitation production.
Proponents of seeding thus argued
that, through the addition of artificial
nuclei, one could enhance the effi-
ciency of the ice-crystal mechanism
and thereby increase rain at the
ground.
Technology quickly provided effi-
cient tools for releasing large numbers
of artificial ice nuclei. Present-day
seeding generators, burning an ace-
tone solution of silver iodide (Agl),
yield effective ice nuclei concentra-
tions of about 1013 to 1014 crystals
per gram of Agl at —10° centigrade,
increasing to about 101'' crystals per
gram of Agl at —20° centigrade. This
means that a single gram of Agl, if
completely and properly dispersed,
would be capable of seeding 100 cubic
kilometers. Technology has not yet,
however, produced adequate tools for
measuring the concentrations of nat-
ural ice nuclei.
A more realistic, more scientific ap-
proach to cloud seeding for altering
precipitation is beginning to emerge.
This approach recognizes, and at-
tempts to relate, several interdepend-
ent factors:
1. There are two known precipita-
tion mechanisms, only one of
which depends on ice nuclei and
only one of which is readily
accessible through present-day
seeding technology.
2. The concentrations of natural
nuclei, both cloud and ice par-
ticles, and the internal structure
of clouds of any given type
differ importantly from time to
time and place to place. For
example, a substantial differ-
ence between cloud spectra in
maritime and continental cumuli
is recognized as due to differ-
ences in the cloud nuclei; ba-
sically, it is this difference in
drop spectra that gives mari-
time clouds their propensity for
warm rain. As a consequence
of such differences, natural
clouds differ markedly in their
response to seeding.
Not all responses to seeding
are desirable. To give an ex-
ample, Project WHITETOP
found that Agl seeding of
summertime cumulus clouds in
Missouri may have decreased
the rainfall by as much as 40
to 50 percent on days with
south winds.
3. The development of precipita-
tion takes considerable time, in
many cases about the same as
the lifetime of the cloud parcels
that nurture the precipitation
development. Thus, most seed-
ing efforts attempt to alter the
time required for precipitation
development relative to the life
of the cloud, or, alternatively,
attempt to extend the life of
the cloud by activating feed-
back loops between changes in
cloud microstructure and cloud
170
PRECIPITATIO I ' ICATION
energetics. The seeding of small
cumuli over Florida and over
nearby ocean areas aims at
complete glaciation of the
clouds to secure the maximum
release of latent heat of fusion,
which in turn might cause
greatly expanded cloud devel-
opment.
4. The optimum number of ice
particles (hence the seeding re-
quirement, if any) depends in a
complex way on the detailed
nature of the cloud and the de-
sired end product. For example
the Bureau of Reclamation
project in Colorado aims at
regulating the number of snow
crystals in the clouds to be the
minimum required in order that
their combined growth rate just
uses up the liquid water of the
cloud by the time the cloud
reaches the crest of the moun-
tain divide. A lesser number
would permit cloud liquid water
to pass over the divide and be
evaporated. A larger number,
and slower growth, might result
in individual crystals being too
small to fall out before crossing
the divide.
Requirements for Scientific
Cloud Seeding
The modern approach to cloud
seeding is to couple the treatment
method to the end object through
specification of the target cloud and
a knowledge of the intermediate phys-
ical processes. To accomplish this re-
quires elaborate systems for real-time
measurement of deterministic meteor-
ological factors, and real-time com-
puter modeling of the physical proc-
esses of the clouds to permit objective
decisions as to when, where, and how
to seed.
Data Base and Related Technology
— The data base on which to develop
a scientific approach to cloud seeding
is uneven. In some areas it is fairly
good, in others almost totally lacking.
The physical properties of cloud and
precipitation particles, and the par-
ticle-interaction coefficients, though
incomplete, are sufficient for most
purposes. Given an initial specifica-
tion of cloud properties, one can make
usable estimates of the growth of a
limited number of precipitation par-
ticles contained therein. Once the pre-
cipitation particles become sufficiently
numerous to interact appreciably, or
in the ever present case of the inter-
action of cloud drops, the bottleneck
is not so much the lack of physical
data as one of computer capability and
mathematical devices to allow one to
keep track of the large number of pos-
sible interactions.
A more serious difficulty is the gen-
eral lack of data on the internal micro-
structure of clouds as a function of
cloud type, season, geography, and
meteorological situation. Instruments
for measuring ice and cloud nuclei are
essentially laboratory devices and
really not suitable for routine field
use. Only recently have tools been
developed for routine measurement of
cloud-particle spectra. We have many
measurements of nuclei and cloud-
particle spectra from research proj-
ects, but we still lack appropriate con-
cepts for generalizing them in ways
to permit useful extension to the un-
measured cloud situation.
Interactions and Downwind Effects
— The feedback loops between the
physics of particles inside clouds and
the energetics of those clouds is al-
most totally unexplored. One can per-
ceive a definite effort in this area in
cloud physics today. Important ad-
vances are likely to come quickly in
terms of the interactions inside single
clouds. But the equally important
problem of interaction between clouds
and cloud systems on the mesoscale
seems much more difficult. Such in-
teractions are well known for the case
of natural clouds. One should suspect
them — indeed, there are signs point-
ing to them — in the case of clouds
altered by seeding. For example,
measurements on Project WHITETOP
indicated strongly that changes in
rainfall due to seeding were accom
panied by changes of opposite sign 50
to 100 miles downwind.
Water and Energy Budgets of
Clouds — An area of general meteor-
ology of great importance to cloud
seeding, and still inadequately ex-
plored, concerns the water and energy
budgets of clouds and cloud systems.
Seeding to change precipitation pre-
sumes to alter the water budget of the
target cloud system, yet studies of
the water and energy budgets of
mesoscale weather systems are almost
totally lacking. Braham carried out
such a study for thunderstorms in
1952. A study of the water budget of
the winter storms involved in the Bu-
reau of Reclamation seeding project
in Colorado is presently under way.
Virtually no other mesoscale weather
system has been so studied. The rea-
sons for this are primarily the inade-
quacy, for this purpose, of data from
the National Weather Service and
the great cost of obtaining additional
data specifically for such studies. Yet
cloud seeding can never be soundly
based until we know in considerable
detail the water budgets of both the
natural and treated storms.
Looking to the Future
The preceding paragraphs are con-
cerned mainly with topics in physical
meteorology concerned with seeding
clouds to alter the amount of precipi-
tation at the ground. There are a
number of other matters that must be
resolved before such seeding can be
adequate for public purposes. Some
of these are scientific in nature, others
are issues of economics, sociology,
and public policy.
Unanswered Questions — Among
the most important issues to be faced
are four unanswered scientific ques-
tions:
1. Under what specific meteoro-
logical conditions (including mi-
crophysics and energetics of
clouds) will a particular treat-
171
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
merit technique result in a pre-
dictable cloud response?
2. Which of the various possible
cloud responses would be useful
to society, in what ways, and
under what conditions?
3. Given that a useful cloud re-
sponse can be predicted from
a particular treatment of some
specific set of initial cloud con-
ditions, are our abilities and
tools for diagnosing the occur-
rence of these conditions suf-
ficient to permit exploitation of
such treatment? In what time-
space scale? In what economic
framework?
4. What is the proper division of
resources between :
(a) basic research, where the
sought-for end product en-
hances knowledge about
clouds and their physical
response to seeding;
(b) pilot projects, where the
chief objective is assess-
ment of the economics of
a particular cloud-modifi-
cation scheme; and
(c) field operations, where the
principal aim is to maxi-
mize the field of a changed
weather element?
Projected Scientific Activity — Be-
cause of the complexity of the at-
mosphere and our limited knowledge
about modifying it, it is likely that
the skill in recognizing seeding op-
portunities can be developed only
from the results of a number of care-
fully designed experimental projects
aimed at testing seeding hypotheses
in various types of weather situations
in different parts of the country.
Project WHITETOP and the Bureau
of Reclamation Upper Colorado Pilot
Project are examples of what these
projects might look like, each of
which will require from three to ten
years. Until such studies are carried
out, scientists will probably be unable
to specify how much precipitation can
be changed, under what conditions,
and how often these conditions oc-
cur. Technology is already at hand
and scientific principles of experi-
ment design are known. We must,
however, be prepared to accept dis-
advantages as well as advantages to
the underlying population.
Economic and Social Implications —
The interactions of cloud seeding with
society are clearly enormous, but they
are hard to detail because we lack
firm information as to how much and
how often precipitation can be modi-
lied, and also because most studies
have emphasized the scientific as-
pects with little regard for the eco-
nomic, social, and political issues.
Since there are few places in the
United States where the economy is
tied to a single economic enterprise,
almost any change in precipitation is
likely to disadvantage some while
working to the advantage of others.
We sorely need studies to learn the
full scope of public cost and public
benetit of changes in weather. We
can start by using the natural vari-
ability of weather and determine just
how a departure of weather from
long-term normality works its way
through the economy of a region.
Such studies — involving the collec-
tive effort of sociologists, economists,
and meteorologists — should be en-
couraged.
Even with such knowledge, one
comes ultimately to the thorny is-
sues of how we decide when and
where to practice weather modifica-
tion, and how the disadvantaged are
to be compensated. Will insurance
companies, for example, "pay off" in
a region of cloud seeding if evidence
develops that increasing rainfall also
increases hail?
The Status of Precipitation Management
Research and operational weather-
modification programs since the late
1940's have served to identify proce-
dures that appear related to precipi-
tation increases. At the same time,
these results have indicated areas
where real understanding and com-
petence are insufficient.
A number of cloud-seeding tech-
niques have been developed. Ground-
based seeding with silver iodide
(Agl), whose crystal structure re-
sembles that of ice (see Figure VI-3),
is the most common technique, espe-
cially for winter storms in moun-
tainous terrain. The seeding ma-
terial is carried aloft by vertical
motion resulting from the instability
of the air or from the lift due to the
mountain barrier. One remaining
fundamental problem involves diffu-
sion of the seeding material. Proper
seeding procedures require (a) that
the proper number of nuclei reach the
effective level in the cloud, and (b)
that the effect of the seeding will be
felt in the desired location on the
ground. The diffusion process is a
rather complex function of vertical
temperature distribution and the
three-dimensional wind field.
Airborne seeding with silver iodide
or crushed dry ice is frequently em-
ployed with summer convective
storms. The primary limitation of
aerial operations is whether or not
the aircraft can fly in weather condi-
tions where seeding will be effective.
Various experimental designs and
statistical evaluation procedures have
172
PRECIPITATION \
Figure VI-3 — LATTICE STRUCTURES OF Agl AND ICE
The models show the crystal structures of ice and silver iodide (Agl). In the model
of Agl, the white spheres are iodide ions and the black spheres silver ions. Although
the crystal structures of both molecules are similar, the lattice constant of Agl is
1.5% larger than that of ice. Partial compensation for the difference can be made by
coprecipitating silver bromide (AgBr) with Agl and substituting Br for as many as
30% of the I atoms in the Agl crystal structure, which will produce a unit cell up to
0.5% smaller than that of pure Agl.
been used. In retrospect, some of
them were inadequate. Nevertheless,
the early programs did show that
cloud seeding has a tremendous po-
tential.
While the bulk of the activity in
precipitation augmentation involves
seeding clouds with artificial nuclei,
other procedures have been proposed
and are being studied. Modification
of radiation processes is an example.
If a large area (several acres or more)
is covered with asphalt, the increased
heating of the air immediately over
the area can lead to strong convective
currents, sufficient under some cir-
cumstances to stimulate the precipita-
tion process. Another possibility in-
volves increasing the humidity high
in the air so that more water would
be available for the natural precipita-
tion processes. Several ideas have
been offered for extracting water
from coastal stratus clouds.
The obvious goal for weather-
modification research, considered as
a whole, is to find the best system
for any given situation. However,
the wide variety of conditions under
which clouds and storms occur, cou-
pled with the different types of to-
pography over which these clouds
develop, show that several, perhaps
many, procedures must be available
to get the best results from every
situation. It is unlikely that the real
world will ever see a truly "best"
system for all conditions. A reason-
able procedure, short of finding the
absolute "best" way, is to put the
available techniques, equipment, and
instrumentation together in such a
way that, under the existing condi-
tions, the desired effect is maximized.
In other words, optimize the available
systems.
What Constitutes a Precipitation
Management System?
A true precipitation-management
system, even a crude and inefficient
one, will have four major compo-
nents: (a) a component to analyze
present and expected water needs
and water sources, as well as the
anticipated effects of precipitation
management on such factors as the
economy and ecology of the area in
question, and arrive at a decision
to employ precipitation-management
techniques; (b) a component to recog-
nize a weather situation where the
application of precipitation-manage-
ment techniques would result in the
desired effect and also, hopefully,
those situations in which the result
would be deleterious; (c) j compo-
nent to select the proper treatment
material and delivery system for the
situation at hand; and (d) a com-
ponent to assess the actual results of
the treatment in terms of useful water
on the ground, economic benefits and
disbenefits, and environmental con-
sequences.
Analyzer Function — The first ac-
tivity of an operational system is to
determine when the application of
precipitation-management techniques
could contribute to the resolution of
a water problem of a particular area.
After the specific need is defined,
the various potential sources of addi-
tional water (e.g., the atmosphere,
water mining, re-use) are examined
to find the best way to fill the need.
The effects of the application of
precipitation-management techniques
on the economics, ecology, and so-
ciology of the area are examined.
Another important consideration
is whether or not the increased pre-
cipitation would fall where a sub-
stantial portion of it would eventually
be usable. There are also legal ques-
tions that must be looked at, such
as ownership of the land being af-
fected, ownership of the moisture
being withdrawn, licensing and in-
demnification procedures, and report-
ing procedures.
When all the available informa-
tion has been considered, a decision
is made. Precipitation-management
techniques may be inappropriate for
a variety of reasons, or they may be
the only techniques available. Usu-
ally, however, precipitation manage-
ment will be used in addition to other
methods of acquiring additional
water.
Recognition — Once a decision has
been made to use weather modifica-
tion in the solution of a problem,
treatable situations must be identi-
fied. Many of the necessary condi-
tions for successful weather modifica-
tion are known, at least qualitatively,
but we do not yet know if these are
sufficient conditions.
173
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
One important factor in determin-
ing whether or not a given weather
situation is treatable is the number of
natural nuclei. Nuclei are needed to
convert vapor into liquid; other nuclei
are needed to convert liquid into ice.
The presence of ice crystals is con-
sidered critical to precipitation for-
mation in most clouds that occur in
the middle latitudes. If liquid drop-
lets are present at temperatures below
freezing, a nuclei deficit is implied.
Such a deficit in an otherwise suitable
cloud can be overcome by the addi-
tion of artificial nuclei. The addi-
tional nuclei will convert some of the
droplets into ice crystals, which will
grow at the expense of the liquid
droplets until they are large enough
to fall out, thereby initiating or in-
creasing precipitation. There are few
routine observations of natural nuclei
numbers, and most counts are made
at the surface, not aloft where the
clouds are. We have only rather
crude notions of how many nuclei
are needed in any given situation.
Some of the other factors of im-
portance in the treatability of a
weather system are temperature
structure, wind, liquid water content
of the cloud, and cloud-droplet size
spectra. Again, we have fairly good
qualitative understanding of the role
of each factor, but we do not com-
pletely understand all the links in the
physical chain of events leading to
the desired result of the modification
attempt. In addition, some of the
pertinent factors are difficult to meas-
ure. Still other factors may be im-
portant in cloud treatability, but our
knowledge of them in real cloud
situations is too meager even for
qualitative statements.
In some situations, theory and em-
pirical evidence have been united in
mathematical models. These models
simulate the atmosphere and can
predict the response of the cloud to
a given treatment. While the models
available today are comparatively
crude, they play a valuable role in
enabling scientists to recognize treat-
able situations.
Treatment — After a situation is
identified as treatable, the appropriate
materials and techniques must be
chosen. The most frequently used
materials for weather-modification ac-
tivities are Agl and dry ice, but many
other substances have been used ex-
perimentally (salt, lead iodide, cal-
cium chloride, and a host of organics
including metaldehyde, phlorogluci-
nol, urea, and 1,5-dihydroxynaph-
thalene). The temperature at which
each of these agents becomes effective
is fairly well known (see Figure VI-4),
as is the particle-size requirement (for
Agl, on the order of 0.1 micron).
Clouds can be classified into two
categories, cold and warm. Cold
clouds are those with temperatures
wholly or partly at or below 0° cen-
tigrade. Warm clouds are those ev-
erywhere warmer than 0U centigrade.
Materials that affect cold clouds
rarely have any effect on warm clouds.
Thus, the treatment material must
be matched to the situation. The
object is to change the size and/or
state of the cloud particles. Precipi-
tation from warm clouds can be in-
creased if the small droplets can be
turned into big droplets.
Hygroscopic materials should be
effective in warm clouds. They are,
in fact, being used experimentally,
though it has proved difficult both to
get the material ground to a small
enough size to stay in the cloud long
enough to be effective and to keep the
particles dry until they are released
to the atmosphere. Once a few drop-
lets large enough to begin to fall are
formed, coalescence should keep the
process going until precipitation falls
out of the cloud.
Hygroscopic materials should also
be effective in cold clouds, but mate-
rials that initiate a phase change are
more efficient. Some cold-cloud
agents, such as dry ice, simply cool
the air and the vapor and liquid in
it to a temperature at which tiny ice
crystals form spontaneously. This
process is effective at air tempera-
tures a few degrees below freezing
Figure VI-4 — TEMPERATURE DEPENDENCE OF NUCLEATING AGENTS
Substance
Effective Temperature
°C
Carbon Dioxide
0
Agl
-4
PbL,
-6
Cud
-7
Loam-Rugby, N.D.
-8
NH4F
-9
v2o5
-10
Loess-Hanford, Wash.
-11
Cdl2
-12
Soil-Baggs, Wyo.
-13
I2
-14
Ash-Crater Lake, Ore.
-17
Dust-Phoenix, Ariz.
-18
Kaolin-Ga.
-23
Diatoms
-31
Spores
-36
The table lists some of the more prominent substances that are used as nucleating
agents and the temperature at which they become effective as nuclei.
174
PRECII I
or lower. Other materials, such as
silver iodide, are known to be effec-
tive, but why they work is not clearly
understood. The crystal structure of
Agl is quite similar to that of ice,
and this was thought to be the rea-
son for its effectiveness. Recent stud-
ies suggest that pure Agl is a rather
poor nucleating material, and that it
must be contaminated with some
other material to be useful in weather
modification.
Different methods are needed to
deliver the various materials to the
cloud. Dry ice is dropped into clouds,
usually from an airplane. The size of
the dry-ice pellets depends on the
vertical thickness of the cloud. Silver
iodide can be released from the air
or from the ground. Ground releases
rely on the horizontal and vertical
airflow to carry the material to the
cloud.
One major problem is to confine
the effects of treatment to a desig-
nated target area. The point on the
ground where the effects will be felt
is determined by the point of release
of the material, the concentration of
the material at the release point, the
diffusion of the material (a function
of the three-dimensional wind field),
the time required for the material to
become effective once it is in the
cloud, and the time required for the
altered cloud characteristics to show
up on the ground. The usual pro-
cedure involves assumptions about
mean values and average times, with
reliance on the skill of the operator
to integrate the various factors sub-
jectively. Several mathematical mod-
els have been developed that predict
the area of effect; as these models,
and the data they use, improve, tar-
geting procedures should also im-
prove.
Despite the uncertainties in how
the material works, how much is
needed, and where and how it should
be released, present capabilities are
sufficient to warrant a certain number
of operational precipitation-modifica-
tion programs. In these cases, the
areas to be affected are relatively
small and the objectives sufficiently
narrow so that the uncertainties can
be taken into account in the program
designs.
Evaluation — The final phase of
a functioning weather-modification
system is evaluation of the results.
Evaluation techniques include the
standard statistical approaches: target
vs. control; treat vs. no treat; ran-
domized crossover, and so on. Both
parametric and nonparametric statis-
tics are used. A few new variations
have been considered but are not
being used except experimentally.
Given a suitable experimental design,
existing statistical evaluation pro-
cedures are acceptable for programs
that go on for several years and in
which the evaluation can wait until
the end of the program.
Full evaluation includes not only
the amount of precipitation produced
but also the economic consequences
of the activity and the effects on the
social and biological environment.
Current Scientific Status
Large quantities of data at or near
the earth's surface have been gath-
ered from experimental areas. Upper-
air data are generally insufficient in
terms and frequency and density.
Because most weather-modification
activities are rather small and inde-
pendent of one another, data gather-
ing is not standardized with respect
to time of observation, duration,
precision, or reliability. Some of the
data from commercial programs are
not readily available. Perhaps the
greatest limitation of the present data
base is the scarcity of measurements
of some of the important factors in
precipitation augmentation, such as
natural nuclei counts. Lack of suit-
able instruments is, in part, respon-
sible for this situation.
Extra-Area Effects — While scien-
tists have not had the quality data
they would have liked, significant
advances have occurred in the past
few years. One interesting phenom-
enon was recently recognized: In
major field programs for increasing
rain, changes in the precipitation pat-
tern well outside the designated tar-
get areas have been noted. The
changes were patterns of negative
and positive anomalies, but the in-
creases were more substantial than
the decreases. This suggests that
some sort of dynamic effect is caused
by cloud seeding, resulting in an
average precipitation increase over a
very large area. These effects are
sometimes felt upwind and laterally
as well as downwind of the target
area. In at least one experiment, the
precipitation of an entire area was
increased, with target-area precipita-
tion significantly greater even when
compared with the precipitation-in-
creased controls. How universal these
effects are and under what conditions
they occur are not clearly understood.
The importance of this phenomenon
in evaluation is obvious.
The Significance of Cloud-Top
Temperature — One of the most im-
portant discoveries of the 1960's was
identification of the importance of
cloud-top temperature on the effec-
tiveness of cloud seeding. Stratifica-
tion of data by temperature indicates
large precipitation increases from
seeded winter orographic clouds when
the temperature at or near the cloud
top is between about — 15 and — 20°
centigrade. When the temperature is
— 25 or colder, precipitation de-
creases from the same kind of clouds
are observed. This suggests that suf-
ficient natural nuclei have a negative
influence on the precipitation process.
Figure VI-5 summarizes some of the
above data.
Technological Improvements — Im-
portant advances have been made
in finding seeding materials other
than silver iodide and dry ice. Many
organic and inorganic materials have
been studied in the field and in the
laboratory. Several of the organics
have been found superior to silver
iodide in many respects, including
cost, and work is progressing on
175
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
Figure VI-5 — OPTIMUM SEEDING CONDITIONS
Dn
Figure
Vl-5(1)
Stat.
Meth.
Scale Change
Sample Size
Stratificati'
Climax 1
Climax II
Wolf
Creek
Climax 1
Climax II
Wolf
Creek
-35 thru -
•26
NP1
NP2
-31
-22
-46
-25
-15
-22
S32, N34
S18, N17
S43, N61
-25 thru -
■21
NP1
NP2
- 1
- 5
+ 6
- 1
+22
+23
S53, N56
S23, N32
S57, N63
-20 thru -
■11
NP1
NP2
+ 100
>+200
>+200
>+200
>+200
>+200
S35, N41
S20, N17
S64, N69
on
Figure
VI-5(2)
Stat.
Meth.
i
Scale Chanj
?e
Sample Size
Stratificati
Climax 1
Climax II
Wolf
Creek
Climax 1
Climax II
Wolf
Creek
0 to <0.7
NP1
NP2
<-50
<-50
<-50
<-50
-20
-24
S24, N21
S15, N12
S33, N33
0.7 to < 1.3
NP1
NP2
+ 11
+ 8
+ 5
+ 16
-14
-15
S76, N86
S36, N42
S58, N81
1.3 to <2.0
NP1
NP2
+ 53
+ 100
>+200
>+200
>+200
>+200
S20, N24
S10, N12
S73, N79
on
Figure
VI-5(3)
Stat.
Meth.
Scale I
Change
Sample Size
Stratificati
Climax 1
Climax II
Climax 1
Climax II
0 thru 11
NP1
NP2
+16
0
- 2
+ 4
S25, N27
S15, N17
12 thru 16
NP1
NP2
+49
+20
+ 9
+53
S27, N21
S16, N13
17 thru 21
NP1
NP2
<-50
-38
<-50
-20
S28, N28
S9, N12
22 thru 27
NP1
NP2
>+200
>+200
>+200
>+200
S26, N25
S12, N13
28 thru 43
NP1
NP2
-40
-39
-32
-32
S14, N30
S9, Nil
The table presents stratified data from three sets of experiments in an effort to show
what factors are important in seeding in Colorado during the winter. The optimum
conditions are summarized as follows: (1) the 500 mb temperature should be
between -11° and -20°C; (2) the computed vertical gradient of potential con-
densate in the 700-500 mb layer should be 1.3 to 2.0 g/kg/100 mb; and (3) the 500
mb windspeed should be between 22 and 27 mps. The probability of each of these
events has been computed, but is not presented here.
making them suitable for operational
use.
Closely connected with new seed-
ing materials are advances in delivery
systems. Increased understanding of
diffusion processes now puts posi-
tioning of generators, either airborne
or ground, on a more objective basis.
New devices for producing nuclei
permit more efficient use of nuclei
material. Advances in radar tech-
niques, coupled with improved under-
standing of cloud characteristics and
dispersion properties, permit safer
and more effective use of aircraft in
seeding operations. The use of rocket-
launched, pyrotechnic seeding de-
vices is receiving considerable atten-
tion.
Modeling — Mathematical models
play an increasingly important role in
both research and operational precipi-
tation-augmentation programs. They
are used operationally in recognizing
treatable situations, in choosing par-
ticular clouds to seed, in specifying
the position of mobile generators so
that the effect will be felt in the target
area, and in specifying the area of
effect from fixed generators. These
models, developed from the basic
laws of physics, are usually relatively
simple, and can be run on moderate-
size computers in near real-time.
More sophisticated models have
been used only for research pro-
grams, in part because present-
generation computers are not capable
of handling them in the time-scale
needed for operational use. The value
of these models lies in suggesting
effects to look for in the field and
in suggesting factors to be studied
in more detail. Three types (scales)
of models are currently available:
(a) microphysics models, which con-
sider the formation and growth of
water droplets and ice crystals; (b) dy-
namic models, which consider motions
and processes within the cloud (see
Figure VI-6); and (c) airflow models,
which consider cloud-forming proc-
esses. None of these models alone is
adequate to describe the complexities
of precipitation augmentation; several
attempts are being made, therefore,
at combining or chaining them.
Implications for Society
Precipitation augmentation is be-
coming an active partner with the
other components of the water-re-
sources system. In many parts of the
nation, it may prove to be the most
economical and socially acceptable
method to increase usable water
supplies.
176
PRECIPITATION Mi ':
Figure VI-6 — SIMULATED EFFECT OF CLOUD SEEDING
10 p 1 1 1| 1 1 1 1 1 1 1 1 1 1 1 ii i| n 1 1 1 " 1 1 1 1 1 1 1 1 m i| m 1 1 1 1 1 1 1 m 1 1 1 1 1 1 1 1 1 1 1 1 " 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
9
U
6 -
5
4 r
3 -
2
1
CLOUD ICE
/ — s
ll 1 1 1 ll II I ll 1 1 1 1 1 1 1 1 ll 1 1 1 1 1
HAIL(GRAUPEL)
I m ■ I ■ n i I i i i i 1 i i i i I i l i l I l i l l I l l l I t n ir
0 12 3 4
KILOMETERS
10 11 12 13
14
15 16 17 18 19 20
io um|nu|inn minimum ii mnn|i ii hhii|ihhihhhihh mm i|in i|in i|m ipn i;m it
9 -
4
3
2
1
0
0 1 2
KILOMETERS
1 1 1 1 1 1 1 i 1 1 1 1
i i i i 1 1 i i 1 1 i i i i I i i t | [ i i i i 1 1 i
16
17
18
19 20
The two diagrams demonstrate a silver iodide seeding experiment done on computer-
generated clouds. The numerical model simulates the growth of cumulus-type clouds
forming over a mountain ridge in a domain 20 km wide and 10 km high. The general
environmental airflow is from left to right. Clouds have formed to the left in the
model and grown to form an anvil present at 7 km. The upper diagram shows the
non-seeded case; the bottom, the seeded case. Seeding is simulated by changing all
cloud liquid to cloud ice and the rain to precipitating ice at -10°C instead of
— 25°C in the natural (non-seeded) case. The hail (or graupel) shown is in concen-
trations greater than 1 gm of hail per kg of air. Rain is in concentrations greater
than 1 gm per kg. These results demonstrate the effects of overseeding — less rain
and less hail come from the seeded cloud since the large amounts of cloud ice that
form are carried aloft and downwind in the anvil.
177
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
Furthermore, precipitation augmen-
tation affects other natural resources
besides water. For example, an in-
crease in precipitation will have an
effect on the natural plant and animal
communities in and around the target
area. Extra water on the soil may
bring additional lands into grazing
capability, but it may also hasten the
leaching of nutrients. The availabil-
ity of additional water may cause
changes in man's use of the land. He
may change the kinds of crops he
grows. He may reap greater harvests
from smaller acreage. None of these
effects, however, is expected to be
large.
Potential Benefits — The interac-
tions between man, his institutions,
and precipitation augmentation are
important. The direct benefit of addi-
tional precipitation is that it helps to
assure an adequate supply of water
for municipal, industrial, and agricul-
tural uses. Secondary benefits include
the generation of low-cost electricity
and assistance in abating air and
water pollution. Relatively small op-
erational projects for water supply
and power generation have existed
for years. What is needed is an in-
tegrated program in which many
benefits can be realized from one ac-
tivity.
Potential Liabilities — Precipitation
augmentation does have associated
liabilities. A few people object to any
deliberate tampering with nature,
some on moral or religious grounds/
others simply on aesthetic grounds.
Some of those who live or work in
the target areas of augmentation op-
erations could suffer financial loss,
especially where the economic bene-
fits are derived some distance away
from the target area. Increased pre-
cipitation in the form of snow could
decrease the growing season and the
tourist season. Erosion could increase
slightly — although, alternatively, in-
creased vegetation from the addi-
tional moisture could cause erosion to
decrease. Undesirable plant life may
increase in certain areas. Increased
snow could raise snow-removal costs
(although an estimate made for the
Colorado Rockies indicates no such
effect for a 10 to 20 percent snow
increase). Potential liabilities exist, at
least in theory, in the possible extinc-
tion of a few species of flora or fauna
and in the modification of river chan-
nels. The net value of precipitation
augmentation must include determi-
nations of the relative importance of
man, nature, and their interaction.
Legal Issues — Precipitation man-
agement raises a variety of legal is-
sues. Who owns the water in the
atmosphere? How should losses re-
lated to precipitation augmentation
be compensated? How should opera-
tions be regulated? How should the
money to pay for operations be ac-
quired (taxation by water district,
state tax, federal funds, etc.)? Should
research projects be treated differ-
ently from operational projects with
respect to liability? When water
needs in one state can be helped by
precipitation augmentation in an-
other, who makes the decisions?
Normative Issues — There are some
reputable scientists who believe that,
while seeding does affect certain
cloud characteristics, there are too
many conflicting results from cloud-
seeding experiments to say that ob-
served precipitation increases from
seeded clouds were caused by the
seeding. But the majority of scien-
tists who question precipitation aug-
mentation ask not "Does it work?"
but "Should we use it?" In other
words, precipitation augmentation,
while far from perfected, is con-
sidered by such scientists to be an
operational reality. Precipitation aug-
mentation today is thus in a position
similar to that of nuclear power
plants several years ago. Discussions
center largely on the risks to people
and the environment and on eco-
nomic feasibility rather than on sci-
entific capability. Answers to these
questions await interdisciplinary stud-
ies of real and hypothetical situations.
Requirements for
Scientific Activity
The practical objective of current
precipitation -augmentation research
is the development of a precipitation-
management system. The system in-
cludes more than the ability to
analyze water needs, recognize op-
portunities, treat opportunities, and
evaluate results. A fully developed
system includes the ability to specify
the results of treatment in advance
with a high degree of confidence. It
includes the ability to specify the
areas that will be affected by the
treatment, as well as the ability to
assess beforehand the environmental
consequences. Such systems need to
be developed and thoroughly tested.
To provide solid answers to the
many unanswered questions of pre-
cipitation augmentation, some im-
proved instrumentation must be ac-
quired. Some sort of standard nuclei
counter is needed. Radar systems
specifically designed for weather
modification are needed to replace the
surplus military equipment now be-
ing used. A variety of airborne and
surface remote-sensing devices would
be useful. Especially needed are de-
vices for determining the moisture
distribution in the air from the sur-
face to about 18,000 feet. Cloud-
particle samplers are needed for
cloud physics measurements. Several
versions are available, but none pro-
vides the scientist with all he needs
to know.
Accurate recognition of treatable
situations is not yet a purely objective
procedure. Better definition of the
essential weather conditions is needed.
Factors such as moisture flux are not
easily measured on the scales needed
for precipitation-augmentation proj-
ects. Mathematical models and the
computers to run them should be an
integral part of the recognition sys-
tem. Improved instrumentation will
be needed to acquire the data for
the system.
The search for more effective treat-
ment techniques must go forward.
178
PRECI
Figure VI-7 — CONCENTRATION OF ICE NUCLEI IN A CITY
The diagram shows the concentration of ice nuclei observed in Seattle. Washington,
from 1 July to 3 November 1968. The scale gives the numbers of ice nuclei per
300 liters of air active at — 21 °C. The concentrations measured in the city were six
times greater than the concentrations of nuclei measured at two unpolluted non-
urban sites. From the plot of the concentrations on the wind rose, it is possible to
deduce that there are sources of nuclei SW and SSW of the sampling site, which
was in the northeastern part of the city. Analyses show that man-made sources of
ice nuclei dominate over natural ones. Just what effect these nuclei have on the
microstructure of clouds, and the development of precipitation, is not known,
although studies in a growing number of cities seem to show that precipitation
increases downwind of industrial areas.
Less expensive and more readily avail-
able materials are needed. Seeding
materials that have beneficial side
effects (such as fertilizing character-
istics) or no side effects are desirable.
More precise delivery techniques are
needed so that the results of the treat-
ment can be properly targeted and
so that the optimum effect can be
achieved.
Better specification of the extra-
area effects recently discovered is
necessary for both targeting and eval-
uation. The causes of the extra-area
effects need to be understood so that
the recognition and treatment systems
can take the effects into considera-
tion. Inadvertent modification of
clouds by atmospheric pollutants is
another vital but little understood
issue. (See Figure VI-7) In some
situations, inadvertent modification
can be controlled. In others, it cannot
be controlled but can be considered
as a factor in the precipitation-aug-
mentation system. Similarly impor-
tant are the interactions between two
or more neighboring augmentation
projects.
Advanced studies of both the posi-
tive and negative interactions of pre-
cipitation augmentation with other
systems need to be carried out. Fac-
tors in the natural environment will
be affected by changes in precipi-
tation. Short- and long-term con-
sequences must be assessed from
scientific, economic, and cultural view-
points. The studies should not be
limited to just the more obvious is-
sues, such as ecological effects. The
studies should consider the entire
environmental system, which in-
cludes man.
Increasing interest in the environ-
ment by both the scientific commu-
nity and concerned citizens' groups
argues for a more deliberate study of
the environment as a system. Much
literature has been circulated recently
suggesting our impending doom if
the quality of the environment con-
tinues to deteriorate. Other studies
have shown that severe water short-
ages will be widespread by the year
2000. While some of these state-
ments may not be rigorously based
on fact, they do suggest the impor-
tance of early development of a tech-
nology that can play a role in en-
hancing both the quality and quantity
of the water portion of the envi-
ronment.
How rapidly the fully devel-
oped precipitation-augmentation sys-
tem described above can be made
available is in part a function of the
level of effort. The first such system
could be operational by 1975. This
system will be effective for win-
ter orographic storm situations in
sparsely populated, high-elevation
areas. Shortly thereafter, a similar
system for convective clouds could
be operational. Through evolutionary
processes, systems for other cloud
situations, and improved versions of
the first, could be available by the
1980's.
179
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
3. FOG
Modification of Warm and Cold Fog
The principal impetus for the de-
velopment of methods for modifying
fog has come from civil and military
aviation. Despite improvements in
instrument-landing techniques, dense
fog over an airport severely restricts
or prevents aircraft landings and
takeoffs. Such occasions, even if they
last only a few hours, impose sub-
stantial financial penalties on the air-
lines, cause inconvenience and loss
to the traveling public, and delay or
abort military missions. Dense fog
is also a serious hazard for marine
and surface transportation. (See Fig-
ure VI-8) On the other hand, fog is
beneficial in certain forested regions
in which the fog-drip from the trees
supplies significant moisture.
The time- and space-scales of fog
and its frequency of occurrence are
all small enough that no large-scale
changes of climate appear likely even
if all fogs were to be dissipated.
However, the climate of certain local
areas with a high incidence of fog
would certainly be changed if the
fog were eliminated.
Cold Fog
Modification of supercooled, or
"cold," fogs by seeding them with
ice nucleants has developed to the
point of operational use at a number
of airports where such fogs are rela-
tively frequent. The scientific basis
for modifying supercooled fogs is
well established; the remaining prob-
lems involve the engineering of reli-
able and economical operational
equipment and procedures.
Nucleants — Cold fogs are seldom
supercooled by more than a few de-
grees centigrade and, therefore, the
Figure VI-8 — A DRIVING HAZARD
The photograph shows a section of an interstate highway running through the valleys
of central Pennsylvania. The valley in the foreground is clear, with excellent driving
conditions. Once the driver enters the gap between the valleys, however, visibility
begins to decrease until it reaches near zero. Although a local phenomenon, this
condition causes many accidents each year.
ice nucleants must have the highest
possible threshold-activation temper-
ature. Dry-ice pellets and liquefied
propane, carbon dioxide, and freon
have typically been chosen to meet
this condition. Silver iodide is not
expected to be effective above — 5
centigrade. Consideration should be
given to the use of certain organic
nucleants such as urea and phloro-
glucinal, which have been reported
to have relatively high activation
temperatures.
Dispensing Methods — To be effec-
tive, the nucleants must be distrib-
uted fairly uniformly through the
volume of fog to be modified. The
earliest, and still the most effective,
procedure is to distribute dry-ice pel-
ets from aircraft flying above the fog;
vertical distribution is assured by the
rapid fall of the pellets through the
fog. Nucleants in the form of fine
particles or liquefied gases must be
introduced directly into the fog,
which may involve hazardous flight
levels. The costs of aircraft seeding
and the limited storage life of dry
ice have led to the development of
ground-based dispensers. Liquefied
refrigerant gases are commonly used,
often with fans or blowers to dis-
tribute the resulting ice crystals
through the fog.
Fog is almost always accompanied
by a wind drift, and the location
and timing of the seeding operation
must be selected so that the clearing
moves over the airport at the desired
time. This requires timely wind ob-
servations, precise navigation for
airborne seeding, or extensive arrays
of fixed seeding dispensers. A wind
shift during the operation may cause
the clearing to miss the airport.
Cost Considerations — Operational
successes in the clearing of cold fog
180
have been reported by the U.S. Air
Force in West Germany and Alaska,
by Orly Airport in Paris, and at
several commercial airports in north-
western United States. Cold fog at
most American airports is so infre-
quent, however, that the standby cost
of a cold-fog modification system
probably cannot be justified. (It
should be noted that the ice fogs
that form in cold regions such as
Alaska cannot be modified by seeding
with ice nucleants.)
Warm Fog
Warm fog is much more common
than cold fog. Many methods have
been proposed over the years for
modifying warm fog, but those that
have shown significant success all in-
volve the evaporation of the fog
drops. The evaporation may be
achieved by heating the air, by dis-
tributing hygroscopic particles in the
fog, or by forcibly mixing the fog
with the drier and/or warmer air
above the fog layer.
Heating was employed at military
airfields in England during World
War II with considerable operational
success. This so-called FIDO (Fog In-
vestigation and Dispersal Operation)
method was further developed at Ar-
eata, California, after the war, and an
operational system was installed at
Los Angeles Airport. Moderate suc-
cess was claimed, but the method
was abandoned because of the large
amounts of fuel required and the
psychological and safety hazards of
operating aircraft between two lines
of flames.
The fundamental unsolved prob-
lem of thermal-fog modification is
the uniform distribution of heating
throughout the fog. In a typical fog,
heating sufficient to raise the air
temperature by about 1° centigrade
will cause the fog to evaporate in a
short time. Arrays of point heat
sources, particularly linear arrays, can
be expected to lead to convection,
non-uniform heating, escape of heated
air aloft, and horizontal convergence
of fog near the surface. The U.S. Air
Force has had some success using jet
aircraft on either side of a runway
as heat sources. Further engineering
developments aimed at providing
reasonably uniform heating by means
of blower-heaters specifically de-
signed for the task may be worth-
while in view of the basic attractive-
ness of thermal-fog modification.
Hygroscopic particles introduced
into fog grow by condensation,
thereby reducing the relative hu-
midity and leading to the evaporation
of the fog drops. This transfer of
the liquid water to a small number
of larger solution droplets leads to
an improvement in visibility in the
fog. More complete clearing occurs
as the solution droplets fall out under
the action of gravity. Hygroscopic
particles act something like ice crys-
tals in a cold fog, with the important
difference that the equilibrium vapor-
pressure over the solution droplets
rises rapidly as the droplet is diluted,
approaching that of pure water.
To minimize the total quantity of
hygroscopic material required to
modify a fog, the hygroscopic parti-
cles should be as small as possible,
consistent with the requirements that
they be large compared to the fog
drops and that they fall out of the
fog in a reasonable time. Since the
solution droplets become diluted as
they fall, the deeper the fog the
larger must be the initial size of the
hygroscopic particles. When the
depth of the fog is more than a few
hundred meters, accretion of the fog
drops by the solution becomes an im-
portant mechanism in the lower por-
tion of the fog.
Mathematical models of the modi-
fication of warm fog by hygroscopic
particles have been devised and used
to guide field experiments. The the-
ory of the growth of hygroscopic
particles and the evaporation of fog
drops is well established. Reasonably
adequate information is available on
the drop-size spectra and liquid
water content of natural fogs. Tur-
bulent diffusion is arbitrarily intro-
duced on the basis of a few estimates
of the eddy-diffusion coefficient in
fogs. However, these mathematical
models are static in that they do not
model the natural processes that form
and dissipate fog. Dynamical models
must be developed that incorporate
these processes. Among other ad-
vantages, such models should yield
the characteristic time of the fog-
formation process. It seems evident
that any artificial modification must
be accomplished in a time that is
short compared to this characteristic
time of fog formation. This is of
the utmost importance in the design
of fog-modification experiments.
In field experiments, hygroscopic
particles have been released from
aircraft flying above the fog. The
usual assumption that the trailing
vortices uniformlv distribute the par-
ticles in the horizontal is highly
questionable. Failure to achieve uni-
form distribution of the seeding par-
ticles is probably one of the principal
causes of unsatisfactory modification
experiments. A non-uniform distrib-
ution can be countered only by in-
creasing the total amount released to
insure that there is an adequate con-
centration everywhere. A closely re-
lated problem is the marked tendency
of the carefully sized hygroscopic
particles to emerge in clumps. Imag-
inative engineering design is needed
to solve these problems, and nothing
is more important at the present time.
Air Mixing — Mechanical mixing of
the warmer and/or drier air above
a relatively thin fog layer will usually
cause the fog to evaporate. The U.S.
Air Force has produced cleared lanes
by utilizing the strong downwash
from helicopters; this technique is
effective only in shallow fogs, how-
ever. The cost/effectiveness ratio is
probably large, but it may be justified
for certain military purposes when
the helicopters are available.
181
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
Summary
In summary, the modification of
cold fogs with ice nucleants is an
operational success, and further en-
gineering improvements are to be
expected; but there are only a few
regions where the frequency of cold
fogs is sufficiently high to justify the
expense of a permanent installation.
Warm-fog modification by heat or
by seeding with hygroscopic particles
is achievable in the relatively near
future. The requirements for success
are more adequate numerical models
of fog and, most importantly, imagi-
native engineering design so that the
assumptions made in the experi-
mental design can be realized in
practice. However, it remains true
today, as thirty years ago, that the
total cost of warm-fog modification
will be high enough to discourage its
extensive application. Some recent
benefit/cost figures are shown in Fig-
ure VI-9.
Figure VI-9 — RESULTS OF FOG-SEEDING PROGRAMS
Air Cancellations
Diversions
Station
Delays Avoided
Avoided
Avoided
Cost
Benefit
Benefit^ Cost
Los Angeles*
60 Hrs.
22
60
$63,000.
$129,790.
2.1
Seattle*
50
21
50
34,500.
96,481.
2.8
Salt Lake City
50
50
27
5,800.
63,650.
11.0
Spokane
25
73
25
4,000.
28,141.
7.0
Medford
7.5
35
15
1,200.
14,970.
12.5
Boise
1
—
2
2,600.
2,157.
0.8
Omaha
6
1
—
2,300.
2,988.
1.3
Des Moines
Total
3.5
2
204
"179
300.
$118,300.
1,793.
$339,970.
6.0
2.9
203 Hrs.
*Cold fog; all other
stations are warm fog case;
The table lists the operational benefits versus costs experienced by United Airlines
during the winter of 1969-70. Benefits have been calculated as monies that would
have been spent were fog dispersal not available or unsuccessful. Cost of delays
were computed from crew salaries, aircraft maintenance, and fuel and oil costs.
Diversion costs included alternate ground transportation, meal and hotel costs,
and overtime charges for ground personnel. Not included were intangibles or
incomputables such as maintenance dislocation, ferrying equipment, need for
reserve aircraft, and mispositioning of flight crews when flights were diverted. Also
not included is the cost of customer inconvenience when fog disrupts operations.
It is of interest to note that benefits were twice the costs of the program at Los
Angeles even though fog was successfully dispersed in only 32% of the cases.
Fog Dispersal Techniques
To assess the present state of fog-
dispersal techniques and define the
work to be done, it is necessary to
consider three types of fog.
Ice Fog
This type of fog is an increasing
problem for aviation and other forms
of transportation in a few high-alti-
tude localities. Comparatively little
research has been done to develop
economical methods of combating ice
fog. The only technique available at
present is the brute-force method of
applying heat to evaporate it. Fur-
ther research is required to assist in
the development of more efficient
means of thinning or dispersing this
type of fog.
Supercooled (Cold) Fog
In the contiguous United States,
approximately 5 percent of the dense
fogs that close airports to opera-
tions are of the cold type. In more
northerly latitudes, the percentage is
higher during the winter. Other
forms of transportation are equally
affected when visibility drops below
one-half mile, but the economic im-
pact is probably not as great as it is
on aviation.
Dry-Ice Dispersing Techniques —
Dispersal of cold fog by seeding
crushed dry ice from light aircraft is
an operational reality at approxi-
mately a dozen airports in the United
States. Some of these programs have
been established each winter since
1962. The physical changes that
182
occur are well understood, stemming
from the research of Schaefer, Lang-
muir, and Vonnegut in 1946. Al-
though the dry-ice technique is
theoretically effective in converting
supercooled water to ice crystals only
at temperatures colder than —4° cen-
tigrade, operational experience has
demonstrated unequivocally that this
technique is effective up to 0 centi-
grade through proper sizing of the
dry-ice pellets and proper control of
the seeding rates for the conditions
prevailing.
This method of dispersing cold fog
is about 80 percent effective. The
failures that do occur are primarily
related to operational problems such
as miscalculating wind drift, which
results in the cleared area moving off
target. Occasionally, too, the tech-
nique is stretched beyond the capa-
bility of the physical reactions to take
place, typically in supercooled fog
decks whose upper layers are several
degrees warmer than 0 centigrade.
Ground Dispensing Methods — Be-
cause of such operational problems
and the complex logistics that are
required in dispersing an airport fog
by means of aircraft, a ground dis-
pensing system, which employs essen-
tially the same physical principles, is
more desirable. Liquid propane has
been used effectively as the seeding
agent; it has reached a degree of
sophistication in France, where con-
trol of supercooled fogs at Orly Air-
port is completely automated through
the use of seventy fixed dispenser
heads deployed around the target
area. Liquid propane has been used
operationally to combat cold fogs in
the United States, but, primarily for
economic reasons, the technology has
never been developed beyond the use
of a few portable dispensing units.
Researchers have suggested that
liquid propane and other cryogenics,
in addition to providing the cooling
mechanism, also alter the fog drop-
lets through a clathration process.
Since this latter process may increase
the effectiveness of liquid propane
in fog temperatures several degrees
warmer than 0° centigrade, further
investigation is warranted. Many air-
ports are subjected to dense winter
fogs with characteristic temperatures
slightly warmer than freezing. De-
velopment of this clathration process
would pay off in benefits at many
airports that cannot support the
more expensive warm-fog dispersal
programs.
Warm Fog
Since all but about 5 percent of
the dense fog that closes airports and
cripples other forms of transporta-
tion in the populated latitudes is of
the warm type, it would be expected
that there has been some preoccupa-
tion with measures to alleviate the
warm-fog problem. Formal research
into fog physics and development of
laboratory techniques for dispersing
fog have, however, been under way
less than forty years. Out of desper-
ation, some brute-force methods for
evaporating fog have been under-
taken where economics was not a
factor.
Houghton's work at the Massachu-
setts Institute of Technology in the
1930's was the first formal research
aimed at fog dispersal. A number
of other studies on warm fog were
subsequently undertaken by federal
military and civilian agencies, but
until the 1960's none of the fog-
modification concepts was applied to
routine commercial or military activi-
ties. Economics, problems of logistics,
or deleterious effects on the environ-
ment were the deterrents.
Modern Techniques — At least one
installation of a refined thermal sys-
tem for evaporating fog at a busy
airport is planned for 1972. Other
thermal methods that utilize energy
more efficiently are under develop-
ment. All of these systems are expen-
sive and will probably be limited to
application at major airports or other
sites where the economic pressure of
fog paralysis is high.
For two years, warm fog has been
regularly dispersed at a few U.S. air-
ports through chemical seeding tech-
niques that had been partially con-
firmed by fog physics research and
laboratory testing. This approach is
feasible, and is producing economic
benefits exceeding costs of the pro-
grams by a factor of about 3 to 1; but
it is considered in the developmental
stage because aircraft dispensing is
required. For full reliability and opti-
mum benefit/cost ratios, a ground
dispensing system must be developed
that will use the most effective mate-
rials. A number of promising con-
cepts have been conceived and some
have been laboratory tested. Further
development work is required, but
success will depend on better basic
knowledge of fog makeup than we
have today.
Basic Warm-Fog Physics — Suffi-
cient knowledge of fog physics exists
to disperse warm fog with heat. The
more attractive and economically
feasible approaches to warm-fog dis-
persal, which do not employ heat,
require more basic physical knowl-
edge in order to develop the most
efficient system.
Recent research involving the use
of hygroscopic materials as seeding
agents has provided some much-
needed knowledge about fog, but
there are still some baffling blind
spots. This new knowledge came fif-
teen years after successful feasibility
tests were conducted, using the same
principle, but which were not con-
tinued because of logistic problems.
It is hoped that another long delay
will not develop before we can ex-
plain, for example, why polymers,
surfactants, and other substances,
when diffused properly, produce posi-
tive results, apparently through a
strong ionization process. Supersatu-
rated solutions of nontoxic materials
with endothermic properties, and
the electrogas-dynamic principle, are
promising dispersal materials and
techniques which require further de-
velopment, as does research on the
physics of fog.
183
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
4. TROPICAL WEATHER
Monsoon Variations and Climate and Weather Forecasting
The monsoon area extends from
western Africa to northeastern Aus-
tralia, being bounded to the north by
the great mountain ranges of southern
Asia. In the southern hemisphere it
encompasses southeastern Africa and
northern Australia but does not ex-
tend beyond the equator over the
central Indian Ocean. (See Figure
VI-10) Its peculiarity, distinguishing
the area from all others, is the marked
difference in prevailing surface wind
directions between winter and sum-
mer. Winds blow predominantly from
continent to sea in winter and from
sea to continent in summer.
Thus, in general, since moist air
covers the continents in summer and
dry air in winter, the summers are
usually wet and the winters dry.
Over the northern hemisphere this
pattern is significantly distorted by
the huge, elevated mass of Himalaya-
Tibet which, through its thermo-
mechanical effect on the atmospheric
circulation, supports the vast perma-
nent deserts east of 70° E. longitude,
insures that India, Burma, and Thai-
land experience arid winters and very
wet summers, and keeps China rela-
tively cloudy and moist throughout
the year.
Except for destructive winds asso-
ciated with relatively rare tropical
cyclones in the China Seas and Bay
of Bengal, the attention of meteor-
ologists in the monsoon area is
focused on only one phenomenon —
rain. Accurate long-range forecasts
for agricultural planning, or short-
range forecasts for irrigation or of
floods would be invaluable to the
economy of every country in the area.
But rainfall variability on every time-
Figure VI-10 — MONSOONAL AREAS
160° 140° 120° 100° 80° 60°
40° 20° W 0° E 20° 40°
60°
80° 100° 120° 140° 160° 180°
60°
40°
20°
N
0°
s
20°
40°
60°
60°
40°
20°
N
0:
s
20°
40°
1 1 1 1 1 1
1
1 1 1 1
1
1 1 1 1^ 1
1
■ — ■— . ^^^ -OX *
1 1 1 1 1 1
\ ) r7 r \ **
s
•a
1
i i i i
i
1 1 1 I 1
? -
160° 140' 120° 100° 80° 60°
40° 20° W 0°E 20° 40°
60°
80° 100° 120° 140° 160° 180°
The map delineates the regions of the world that are monsoonal — i.e., where the
prevailing wind direction shifts at least 120 degrees between January and July. By
sharpening the definition according to principles developed by Ramage, it is possible
to define the true monsoon area as that included in the rectangle shown covering
large parts of Asia and Africa.
and space-scale — from inter-annual
to diurnal and from intercontinental
to mountain/valley — render clima-
tology of limited use in providing the
necessary planning information.
Status of Tropical Meteorology
Long-Range Forecasting — Most
existing work was done in India and
Indonesia before World War II. Mul-
tiple-regression equations based on
lag correlations were first used in
the lQ20's to forecast seasonal rain-
fall. Unfortunately, performance was
disappointing — droughts and floods
were never anticipated and predictor/
predictand correlations proved to be
most unstable. Apart from a modest
continuing search in India for new
correlations, little effort is now being
made.
Unless the deterministic forecast
methods to be tested in the Glo-
bal Atmospheric Research Program
(GARP) perform much better than
even their most optimistic proponent
expects, there is little chance of use-
ful developments in forecasting sea-
sonal rainfall extremes.
Short-Range Forecasting — For the
past fifty years the practice of tropical
meteorology has been distorted (usu-
ally unfavorably) by uncritical graft-
ing of hypotheses and techniques
developed in middle latitudes. As one
scientist has observed:
We have again and again ob-
served very reputable and highly
specialized meteorologists from
higher latitudes who were deter-
mined to solve the problems of
tropical meteorology in a very
short time by application of mod-
ern scientific methods and use of
new scientific resources such as
184
computerization. Then, after a few
years, they find out that the thing
doesn't quite work this way and
the tropics cannot be approached
by the methods used to solve prob-
lems in higher latitudes.
Training of Tropical Meteorolo-
gists — Almost e'very professional me-
teorologist in Burma and Thailand
holds an advanced degree in meteor-
ology from a foreign university, and
yet their contributions to knowledge
of even their own country's meteor-
ology has been miniscule. In part,
this is because many monsoon-area
meteorologists have received inten-
sive training in other countries, espe-
cially in the United States and the
United Kingdom, but almost never by
teachers with any experience in, or
appreciation of, monsoon meteor-
ology. In this country, even the
tropical meteorologists who instructed
them, confidently and quite unjustifi-
ably, would extrapolate their tropical
oceanic experience to the continents.
Numerical forecasting is the latest
invader from the higher latitudes.
Since some of the training received in
other countries is at last beginning to
seem relevant, everyone with access
to a computer is trying out the
models. Despite the fact that none
of the models has demonstrated any
weather forecasting skill over the
Caribbean and around Hawaii, and
despite the fact that problems of
grid-mesh size are even more critical
over the continents than over the
oceans, resources which can ill be
spared are being squandered on the
latest fad — on the unsupported and
unjustified assumption that numeri-
cal forecast techniques have already
significantly improved on subjective
analysis and forecasting in the tropics.
The machine churns out reams of
charts — while professional meteor-
ologist positions remain unfilled.
In the monsoon area, the best aid
to local forecasting is the cloud pic-
ture from an Automatic Picture
Transmission (APT) satellite. But the
only way to use this information
intelligently is through hard, subjec-
tive evaluation, and this is so un-
fashionable that a computer is often
considered more desirable than an
APT read-out station. A monsoon-
area meteorologist, after intelligently
and deliberately studying a detailed
climatology and a sequence of care-
fully analyzed synoptic and auxiliary
charts (including APT pictures), can
forecast consistently better than
chance and significantly better than
a numerical model. A statistical pre-
diction should always be available to
him. He should modify that predic-
tion only when he discovers a sig-
nificant change trend in the charts.
When in doubt, stay with statistics.
This may seem obvious, but such
down-to-earth advice is rarely given
during academic instruction.
Training Facilities in the Tropics —
If training in middle-latitude institu-
tions is so inadequate, what about
indigenous programs?
In Asia, the Royal Observatory,
Hong Kong, is a good but small cen-
ter of research, emphasizing urban
pollution and hydrological planning.
Useful, practical, and theoretical
studies are being pursued in the
People's Republic of China. The In-
stitute of Tropical Meteorology in
Poona, India, is conducting good cli-
matological studies but is also un-
critically applying numerical forecast
models developed in Washington,
D.C., and Honolulu. The program in
the University of the Philippines,
launched with some fanfare three
years ago, has apparently made no
progress — an expensive faculty waits
for enrollments but is ignored by
meteorological services in the region.
The Department of Geography in the
National University, Taipei (Taiwan),
has done good work, particularly on
the effects of typhoons, while the
Department of Oceanography in the
University of Malaya (Kuala Lumpur)
has made a promising beginning with
useful climatological and synoptic
studies.
Apart from a small department of
meteorology in the University of
Nairobi, in Kenya (which has turned
out at least one promising scientist),
and, possibly, some activity at the
University of Ibadan, in Nigeria,
nothing much seems to be happening
in Africa. Australia largely neglects
monsoon meteorology except for a
small in-house effort in the Regional
Meteorological Center, Darwin.
Over-all, the U.S. military interest
in southeast Asia has contributed
more to meteorological research and
to improvement in meteorological
training in the monsoon area over
the past five years than any other
factor. Research conferences spon-
sored by defense agencies have pro-
duced significantly more than just
military benefits. One spin-off was
the World Meteorological Organiza-
tion training seminar conducted in
December 1970, in Singapore.
Summing up, short-range monsoon
weather forecasting can be improved,
but there is little chance of improve-
ment stemming from the BOMEX ex-
periment in the Atlantic (see Figure
VI-11) or from continued training of
monsoon-area meteorologists in insti-
tutions with little understanding of,
or interest in, the peculiar problems
of monsoon weather. More can prob-
ably be done by supporting the efforts
in Taipei, Hong Kong, Kuala Lumpur,
and Nairobi, particularly in the direc-
tion of temporarily assigning out-
side experts (perhaps on sabbatical
leaves) to these places. The experts
might even learn something from the
experience!
Scientific Communication — One
other serious problem is that research
into monsoon meteorology is pro-
vincial. Investigators have seldom
been aware that in other monsoon
regions similar problems have been
under study or even solved. Insuffi-
cient scientific communication partly
accounts for this. The only widely
distributed journals are published in
middle latitudes. Regional journals
or research reports are often well dis-
tributed beyond the monsoon area
but poorly distributed within it.
185
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
Figure VI— 1 1 — ARRAY FOR BARBADOS OCEANOGRAPHIC
AND METEOROLOGICAL EXPERIMENT (BOMEX)
60,000 Ft
• SAINT MARTIN
!
N0RTH ■ ^ -
RAINIER
500 W /j GILL
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-r
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TRADE
WINDS
1 Array will be oriented at right
angles to Mean Trade Wind
UNDAUNTED fT^
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ttW^BMr DISCOVERER
r
BARBADOS
MT MITCHELL
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• Land Based Station O Current Stations
Thermistor Array Moorings
The deployment of instrument platforms for BOMEX is shown in the diagram. This
figure represents the consequence of designing a group of experiments of sufficient
scope and precision to test hypotheses and obtain useful new data from an
intermediate-scale system. The event is unique in human history. This experiment
was participated in by the Departments of Commerce, Defense, Interior, State, and
Transportation, the National Aeronautics and Space Administration, Atomic Energy
Commission, the National Science Foundation, National Center for Atmospheric
Research, and more than 10 universities.
Basic Concepts
The general character of the mon-
soons and their inter-regional varia-
tions reflect the juxtaposition of con-
tinents and oceans and the presence
or absence of upvvelling. However,
without the great mechanical and
thermal distortions produced by the
Himalayas and the Tibetan Plateau,
the vast northern-hemisphere deserts
would be less desert-like, central
China would be much drier and no
colder in winter than India, while
even over the Coral Sea winter cloud
and rain would be uncommon.
Within the monsoon area, annual
variations are seldom spatially or
temporally in phase. Even if these
variations were understood and their
phases successfully forecast, accurate
day-to-day weather prediction would
not necessarily be achieved, for the
climatological cycles merely deter-
mine necessary conditions for certain
weather regimes; synoptic changes
then control where and when the
rain will fall, and how heavily, and
whether winds will be destructive.
Synoptic-Scale Changes — Al-
though not new, a most important
concept is that of wide-ranging,
nearly simultaneous accelerations or
decelerations within a major vertical
circulation. Causes are elusive, al-
though the changes generally appear
to be triggered by prior changes in
the heat-sink regions of the vertical
circulation. This is a field of truly
enormous potential for numerical
modeling, on a time-scale between
synoptic and seasonal, in which fluc-
tuations in radiation and in air-
surface energy exchange might pro-
duce profound effects.
The concept both explains previous
difficulty in maintaining continuity
of synoptic analysis and demands
that notions of day-to-day weather
changes be examined and probably
modified. Even during winter, fronts
seldom remain material boundaries
for long and air-mass analysis con-
fuses more often than not.
That synoptic-scale disturbances
often appear to develop and to
weaken in response to changes in the
major vertical circulations might ex-
plain why many of the disturb-
ances are quasi-stationary. In turn,
synoptic-scale vertical motion deter-
mines the character of convection and
the efficiency with which energy is
transported upward from the heat
source.
Synoptic-scale lifting, by spreading
moisture deeply through the tropo-
sphere, reduces the lapse rate and
increases the heat content in mid-
troposphere. Thus, though it dimin-
ishes the intensity of small-scale
convection and the frequency of thun-
derstorms, it increases rainfall and
upward heat transport. Conversely,
synoptic-scale sinking, by drying the
mid-troposphere, creates a heat mini-
mum there, hinders upward transport
of heat, and diminishes rainfall. How-
ever, the increased lapse rate favors
scattered, intense small-scale convec-
tion and thunderstorms.
186
In the monsoon area, the character
of the weather, on the scale of indi-
vidual clouds, seems to be determined
by changes occurring successively on
the macro- and synoptic scales. Rains
set in — not when cumulonimbus
gradually merge but when a synoptic
disturbance develops, perhaps in re-
sponse to change in a major vertical
circulation. Showers, too, are part of
the synoptic cycle. Individually in-
tense, but collectively less wet, they
succeed or precede rains as general
upward motion diminishes.
When synoptic-scale lifting is com-
bined with very efficient upper-tropo-
spheric heat disposal, the lapse rate
may be steep enough to support in-
tense convection. Then, a vast, "con-
tinuous" thunderstorm gives pro-
longed torrential rain. Many times
this takes place within the common
upward branch of two major vertical
circulations.
Needed Scientific Activity
Many tropical meteorologists have
striven to make their work appear as
quantitative and objective as possible.
This commendable aim has led to im-
portant climatological insights. How-
ever, in synoptic studies their quanti-
tative results have usually been belied
by nature's quantities. A numerical
model which determines that air is
massively rising over the deserts of
Arabia has limited validity no matter
how quantitative and objective it
might be. Energy-budget computa-
tions in which precipitation and
evaporation are residuals, or must be
estimated, have also had their day.
Forecasting and research should be
inseparable. The very few monsoon-
area weather services that enable
their forecast meteorologists to spend
at least one-third of their time on
research have thereby greatly en-
hanced staff morale and their scien-
tific reputations, to say nothing of im-
proved forecast accuracy. Combined
forecast-research programs could well
be successfully directed to solving
problems and to increasing the num-
ber of recognizable models of synop-
tic circulations.
The area covered by synoptic analy-
ses should be sufficiently broad for
the major vertical circulations to be
monitored. Then interaction with
synoptic disturbances and consequent
effects on rainfall could be detected
and possibly anticipated.
Mesoscale gradients within synop-
tic systems and their diurnal varia-
tions might be better understood
were studies to combine information
from weather radars and weather
satellites. Ceraunograms could help
bridge the gap between meso- and
synoptic scales. Aerial probing of con-
tinuous thunderstorms would likely
illuminate the shadowy picture we
now have of energy transformations.
We should view the future of mon-
soon meteorology with optimistic dis-
content. Regional progress in under-
standing and forecasting weather has
been disappointingly slow. However,
attacks are being vigorously pressed
on problems of concern to the entire
monsoon area. What is needed is the
hitra-nrca exchange of people and
ideas.
Tropical Meteorology, with Special Reference to Equatorial Dry Zones
The outlook for meteorological ob-
servations in the tropics, as now
programmed, is excellent for many
purposes and far superior to the past.
Much can be done with existing and
prospective observations in the way
of field experimentation and synoptic-
statistical modeling. Ambitious proj-
ects like special or worldwide net-
works or expeditions, however, should
be undertaken only if the necessary
data base is really assured. Further-
more, meteorology, as a discipline, is
still far too self-contained; special
efforts are needed to promote inter-
disciplinary research.
Four problems are particularly in
need of concentrated research in tropi-
cal meteorology during the 1970's:
Water Supply — This age-old prob-
lem is becoming aggravated by popu-
lation increases in tropical countries,
as elsewhere. The need is to find
ways to assure an adequate water
supply over the middle and long
term — i.e., on a seasonal or annual
basis. Several avenues of scientific
development could be promising:
First, it has become more than ever
urgent to improve weather-prediction
methods. Second, experiments for in-
creasing precipitation artificially need
to be broadened to see whether
(a) such increases are possible at all
on tropical land areas; and (b) enough
water can be produced by man to
make a significant difference. While
not directly a part of meteorology,
desalination of sea water and diver-
sion of large rivers (e.g., part of the
Amazonas in northeast Brazil) also
offer possibilities for enhancing tropi-
cal water supplies.
Tropical Storms — Again, the prob-
lem has both predictive and modifica-
tion aspects. Prediction beyond 12 to
24 hours remains a large problem in
the areas affected by tropical storms
and hurricanes. The German Atlantic
Expedition of 1969 has again raised
the question of whether tropical
storms can be "modified" and, in-
deed, whether or not it would be wise
to do so. It should not be overlooked
that tropical storms in many situa-
tions and many areas bring great eco-
nomic benefits, even though news re-
187
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
leases usually cite only the damage
they cause.
Role of the Tropics in the General
Circulation — The role of the tropics
in hemispheric or global circulation
is known to be important. The long-
term (five days or more) prediction
models now being developed require
a tropical data input that is not vet
adequate. In particular, studies are
needed of (a) how constant the
tropics are as a source of energy and
momentum, and (b) the appropriate
way to include in the models the
energy infusions into the atmosphere
from more or less point sources ■ —
i.e., from small-area cumulonimbus
cloud systems. In addition, ways
must be found to represent surface
interface processes, not only evapo-
ration and sensible heat transport,
but also momentum exchange, espe-
cially on the equator itself.
Hemispheric Interchange — Any
interconnection between the extra-
tropical regions of both hemispheres
must take place via the tropics. From
the spread of various tracers or aero-
sols, over a scale of weeks or months,
we know that an exchange of air does
take place. An understanding of
these exchanges is particularly rele-
vant to problems of air pollution.
Actual pollution problems in the
tropics are not likely to become
severe because of the unstable strati-
fication, although tropical countries
are, of course, exposed to sedimenta-
tion or washout of pollutants by pre-
cipitation. In the longer view, how-
ever, the ability of the air to transport
pollutants across the equator requires
serious study of the air exchange —
its mobility, the magnitude of the
exchange, preferred paths, and the
like, with a view to eventual control
of such transports.
Needed scientific activity under
each of these major categories is dis-
cussed in the sections that follow.
Tropical Water Supply
Some parts of the tropics are sub-
ject to recurrent, severe droughts.
Those of northeast Brazil, which have
led to large out-migrations of popu-
lation and great economic and politi-
cal instability in all of Brazil, are an
example. These droughts, superim-
posed on an average rainfall that is
itself marginal for a tropical economy,
have lasted from two to as long as
nine consecutive years. The longer
droughts have occurred in the more
recent part of the climatological rec-
ords, suggesting a secular drying out
— a most unfavorable circumstance.
Many scientific questions remain
before such tropical droughts can be
understood, much less controlled.
The droughts (as well as the inter-
mittent heavy rainfall years) must be
related somehow to the anomalies of
the northern- and southern-hemi-
sphere general circulations and pos-
sibly to some oceanic temperature
distributions that do not follow di-
rectly from anomalous surface trade-
wind speeds and directions, as well
as to associated surface divergences
or convergences. But the controls
that govern these relationships are
completely unknown at present. Lack
of data over the tropics, the southern
oceans, and even the North Atlantic
at lower latitudes has prevented any
definitive study. Little adequate use
has been made of such information as
is available — surface temperature,
pressure, and precipitation anomalies
over wide areas, as well as recent
findings on wind anomalies over the
equatorial Atlantic.
Data Base — New data are accumu-
lating very fast for all parts of the
tropics, eliminating the old excuse
that lack of observations prevents
progress. Data have been accumu-
lating from the rapidly growing num-
ber of commercial flights over tropi-
cal areas. Programmed new satellite
data are adding even more rapidly to
the pile. An energetic attack on the
discovery of the controls of equatorial
dry zones and variable rainy seasons
should be possible in the 1970's as a
result of these new data. Once the
controls are known, it will be possible
to see whether prediction of the con-
trol functions can be achieved with
synoptic-statistical modeling tech-
niques, although direct deterministic
prediction does not appear in the
picture for the foreseeable future.
Cloud Modification — The ques-
tion of cloud-modification potential
in the tropics remains unresolved.
Nonprecipitating cumulus congestus
may be a preferred cloud form over
many semi-arid tropical areas. But
past efforts to study the possibilities
of modifying such clouds have been
rather sporadic. Early interest in Aus-
tralia has lagged. A few serious cu-
mulonimbus studies have been made
in the Caribbean, but these relate
to the atmosphere over open sea;
since surface heat sources are much
stronger over land, these oceanic ex-
periments cannot be applied directly
to the tropics, although they may be
useful indirectly if they are successful
in making cumulonimbus grow.
Quite apart from modification ex-
periments, it would be of value
merely to learn the cloud composition
at different locations in order to
assess what might be termed the
"stimulation potential." Even in this
respect, knowledge has remained de-
ficient. There exists on this subject a
great need not only for scientists but
also for adequate instrumentation
(notably radar) and good technicians.
Good radar technicians actually avail-
able for meteorology are rare, and in
tropical countries they tend to be
either nonexistent or insufficiently
skilled. The World Meteorological
Organization has a large technician-
training program, which merits sup-
port.
Tropical Storms
Tropical storms are notoriously
variable in frequency from year to
year and region to region. (See Figure
VI-12) Sometimes the connection with
the general circulation is obvious, but
not always. The role of hurricanes in
the general circulation is not yet fully
determined, and general-circulation
research, with a focus on general cir-
188
Figure VI-12 — FREQUENCY OF TROPICAL CYCLONES
North Atlantic Ocean 73
North Pacific — off west coast of Mexico _. 57
North Pacific Ocean, west of 170°E ..... . 211
North Indian Ocean, Bay of Bengal 60
North Indian Ocean, Arabian Sea 15
South Indian Ocean, west of 90°E 61
South Indian Ocean, northwestern Australia 9
The table shows the frequency of tropical storms per 10 years. The numbers are
only estimates of the number of tropical cyclones to be expected, since, until
recently, there have been no reliable statistics except for the Atlantic, where ship
traffic has been heavy and island stations numerous for many years. Surveillance
by satellites will provide worldwide coverage of tropical cyclones.
dilations favorable or unfavorable to
tropical storms, is definitely needed.
Clearly, such storms are not mere
nuisances. A single hurricane can re-
place the function of the equatorial
trough zone in the Atlantic for verti-
cal transport of heat and moisture
and their transmission to higher lati-
tudes.
Altogether, the true value of such
storms — when, where, and under
what circumstances needs to be
stressed and measured. Coastal dam-
age and associated flooding from hur-
ricanes in areas such as southeastern
United States usually receive the
widest publicity. It is forgotten that,
as these storms move slowly inland
and turn into unspectacular inland
rains, they have on occasion saved
the cotton crop and even relieved
water shortages of cities such as At-
lanta. Lowered water tables over
southern Florida and other areas, with
their danger of salt-water intrusion
into the water supplies of cities like
Miami, can also be counteracted by
hurricane precipitation. In terms of
dollars, then, hurricanes can often
bring benefits that are comparable to
the damage they cause.
Impact of the Tropics
on World Weather
Long-Period Trends — As the en-
ergy and momentum source for the
general circulation, the tropics are
most likely to have an important im-
pact over long time-scales (from
months to years). The excess of
energy acquired and held by the
tropical oceans may undergo slow
variations of possibly great impor-
tance for long-period circulation
anomalies. Bjerknes, for example,
has speculated on the equatorial Pa-
cific and its influence over large areas
beyond the tropics.
Expanded observational networks
at sea and, again, satellite data now
appear sufficient for empirical re-
searches to begin on such aspects
of general circulation. Theoretical
modeling would also be useful to in-
dicate how much variation in the
tropics is needed to produce an even-
tual circulation upheaval elsewhere.
From models that have been run so
far, it appears that the heat accumu-
lations or deficits need not be very
large.
The intensity of the mean merid-
ional circulation is also a matter for
serious study. Data are marginally
sufficient to calculate this circulation
on a monthly, if not weekly, basis.
Variations in the cell have hardly
been considered at all; yet they would
profoundly affect, among other
things, the energy and momentum bal-
ance picture, subtropical jet streams,
stress in higher latitudes on the
ground, and relations to the intensity
of the Siberian winter high.
Short-Period Fluctuations — Vari-
able exchanges with the tropics may
be responsible for the "index cycle"
of the general circulation in the west-
erlies on a two- or three-week scale.
Prediction experiments now planned
in connection with the Global At-
mospheric Research Program (GARP)
may or may not lead to an under-
standing of such influences. Sepa-
rate studies — using diagnostic data
from the National Maritime Commis-
sion and other hemisphere analyses
and data storages — would also be of
considerable value. Such studies
could also investigate whether the
exchanges are forced from higher
latitudes, and in this way learn more
about the mechanisms for the vari-
ability of the atmospheric machine.
For prediction equations, much em-
phasis has been given to parameter-
ization of cumulonimbus convection,
since a few thousand cumulonimbus
cover roughly 0.1 percent of the
tropics at any one time. Much re-
search on this subject is under way,
although some dispute remains as to
the form the research should take.
GARP takes the view that a master
tropical experiment must be con-
ducted for final clarification. While
a series of smaller projects might be
inadequate for the problems to be
solved, the master experiment may
not succeed either, since experimental
difficulty increases nonlinearly with
the size of an experiment. Further-
more, there is a deplorable tendency
to ignore the results of past expedi-
tions in writing the prospectus for
new ones; in present planning, for
example, such large undertakings as
the German Atlantic Expedition and
its results have been generally over-
looked.
Emphasis should not be placed ex-
clusively on oceanic observations.
Obviously, the oceans hold much of
the key to world weather; but pre-
dictive models should eventually be
geared mostly for continental areas,
189
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
where predictions are most needed.
Continental models will necessarily
differ from oceanic ones. Continents
do not have surface-heat storage in
the sense of the oceans, and frictional
stresses as well as nuclei spectra for
condensation and freezing are differ-
ent. Oceanic research could thus use-
fully be supplemented by research
over land. Collaboration with exist-
ing continental experiments, such as
that of northeastern Brazil, could
bring large technical rewards.
Interhemispheric Communication
In many ways, it appears that the
center of the equatorial convergence
zone separates the hemispheres mete-
orologically as well as physically.
Each has a self-contained energy and
momentum budget, for example. If
this picture were true for all time-
scales, then the two hemispheres
could be treated as independent of
each other for all practical meteoro-
logical purposes.
No one really believes this, how-
ever, although there is much doubt
as to the time-scale on which inter-
hemispheric mechanisms are impor-
tant. Preliminary calculations based
on data dating from the International
Geophysical Year (IGY), in the
1050's, have not revealed any impor-
tant connections; but then, the tropi-
cal network of IGY was so deficient
that it is impossible to treat these
data as definitive. Here we see the
danger of inadequate observational
efforts. Better data are likely to
emerge from superpressure balloons,
World Weather Watch stations and
satellites, and the buoys and other in-
stallations of the GARP network. If
these networks and data sources are
kept up and expanded, a good start
could be made during the 1^70's on
resolving the questions relevant to
the importance of interhemispheric
communication for long-range
weather changes.
Irrespective of long-period weather
control, an understanding of mass ex-
changes across the equator is impor-
tant to the prospects for worldwide
pollution control. We know that mass
exchanges across the equator occur,
but we need to determine whether the
drift of pollutants across the equator
occurs with indifferent distribution in
troposphere and stratosphere. If that
is the case, nothing can be done to
protect one hemisphere from the
other, but there may be point-, or
small-area, injections in preferred and
stationary locations. If that is so,
trajectory calculations toward these
areas and measurements along them
would at least permit warning of im-
pending transports of particular pol-
lutants at a high level.
190
5. DUST
African Dust and its Transport into the Western Hemisphere
Meteorologists have recently dis-
covered that enormous quantities of
dust are raised over arid and semi-
arid regions of North Africa and in-
jected into the trade winds over the
North Atlantic. Outbreaks of dust
from the Sahara take about one week
to reach the Caribbean. The amounts
of dust are highly variable in space
and time, both from day to day and
season to season, but the period of
maximum dust transport across the
Atlantic (June to early September)
coincides with the Atlantic hurricane
season. Dust outbreaks from Africa
often appear on meteorological satel-
lite photographs as a semi-transpar-
ent or transparent whiteness that re-
sembles thin cirrus clouds. (See
Figure VI-13) In such outbreaks,
surface visibility can be moderately
reduced as far west as the Caribbean.
African dust outbreaks and the
hurricanes that also have their origin
over Africa may be interrelated in
some ways. While it is highly un-
likely that African dust can cause
wind disturbances to form into hur-
ricanes or hurricanes to dissipate,
there is enough observational and
theoretical evidence to suggest that
the two phenomena might affect each
other indirectly or directly in a sec-
ondary role. The dust's ability to
directly influence hurricanes lies in its
ability to affect the thermodynamics
of cloud growth through its role as
an ice or condensation nucleator.
More indirectly, the dust can affect
the energy balance of the tropics by
its ability to block incoming radiation
from the sun or outgoing infrared
radiation from the earth's surface.
Dust can also serve as a tracer of
atmospheric air motion. There is
some evidence that an enhanced dust
transport accompanies the movement
of wind disturbances off the west
coast of Africa. The dust content of
the air can be modified in the disturb-
Figure VI-13 — DUST OVER THE TROPICAL ATLANTIC
This satellite photograph was taken by the ATS-3 satellite on the afternoon of August
11, 1970. It shows a great cloud of African dust between 30° and 60° W. longitude
just north of the Tropic of Cancer.
ance either by being washed out in
rain or by being evacuated to very
high altitudes in the updrafts that
accompany giant cumulus clouds.
When it is transported to levels well
above the 3- to 4-kilometer depth
over which it is normally found, the
dust can more readily affect the en-
ergy balance and particulate concen-
trations in other parts of the globe.
Characteristics of Dust Transport
Since 1965, quantitative measure-
ments of windborne dust transport
have been made on a year-round
basis at a tower on the island of Bar-
bados, in the lower Antilles. (Re-
cently, two more such stations have
been set up to measure dust in Ber-
muda and Miami.) These measure-
ments, made by scientists from the
University of Miami, show that the
airborne dust loading is highly vari-
able from day to day, season to sea-
son, and even year to year. Like
hurricanes, the primary activity is in
summer when the dust transport
averages 10 to 50 times more than in
winter, with the daily amounts vary-
ing from about 1 to 40 micrograms
per cubic meter.
Variability — Air-trajectory analy-
sis shows that the summer dust orig-
inates over arid to semi-arid regions
in the northwestern corner of the
African continent, and is swept south-
ward and toward the Caribbean by
the strong northeasterly winds that
exist in that sector during summer.
The width of the dust-carrying air-
stream is only 300 to 500 miles wide
as it leaves the coast of Africa, and
the depth of the dust layer is about
12,000 feet as determined by the
depth of mixing over Africa. Al-
though this flow of dust is more or
191
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
less continuous, the variations in dust
content of the air are often quite
abrupt.
Locally, the variation in dustiness
can be due simply to a shift in the
dust-laden airstream. In many in-
stances, large increases in dust load-
ing in the Caribbean can be tied to
specific outbreaks of dust-storm ac-
tivity over parts of North Africa. At
other times, the increases in dust load-
ing of the trade winds are attribut-
able to the venting of the normally
dusty air over the African continent
by a favorable wind regime which
brings air from deep in the interior of
the Sahara into the Atlantic trade
winds. In many cases, however, it is
impossible to assign a cause to the
dust outbreak or even to detect the
variation of dust loading downwind
from Africa without direct measure-
ments.
Visibility — The presence of Afri-
can dust in the Caribbean can be seen
as thick haze, with visibility reduced
from 20 to 30 miles, in the case of no
haze, to only between 6 and 15
miles. In exceptionally hazy areas of
the Caribbean, the horizon resembles
that on a dry day of the American
Midwest or on a muggy day in a large
city of the Northeast. Indeed, the
dust loadings over the Caribbean are
probably comparable to or greater
than those that would be found over
much of continental United States.
Source — There is an abrupt
change in the general source region
of the dust between winter and sum-
mer. After October and until May
(with some rare deviations), the dust
is ash-gray to black and is thought to
originate over the sub-Sahara from
the Cameroons through central Ni-
geria and the Ivory Coast. In the
summer, however, the flow of dust
is primed by the strong northeasterly
winds associated with the intense
pressure gradient that exists between
the low pressure of the central
Sahara and the relatively high pres-
sure along the western coast. Then,
the dust is a reddish-brown color
with a tinge of yellow.
Particle Size — A surprising as-
pect of the size spectra of the dust
reaching the Caribbean is the rela-
tively large fraction of the dust (5 to
20 percent) with particle sizes in ex-
cess of 10 microns. In general, the
higher the dust loading the higher is
the fraction of dust in the larger size
ranges. According to Stokes, settling-
velocity particles in excess of 10
microns would settle out of the air
before reaching the Caribbean unless
they were raised to heights well in
excess of 20,000 feet. Since the visible
dust top is rather distinct at about
10,000-15,000 feet over the Carib-
bean, and is directly related to the
top of the turbulent mixing layer over
the Sahara, which is at about the
same altitude, one can assume that
virtually all the dust falls from below
10,000-15,000 feet. Although a sub-
stantial fraction of the dust un-
doubtedly settles out before reaching
the Caribbean, a certain fraction of
all size ranges is prevented from
being lost by the recycling of air
(turbulent mixing) in the dust layer
over Africa and in the trade winds.
Vertical Distribution — Recent ob-
servations of the vertical distribution
of the dust show that the dust con-
centration in the air downwind from
the Sahara is greatest in the layer
between the dust top and the top of
the cumulus layer (say, 4,000 to 8,000
feet). In the lower layers, the trade-
wind air may be air of non-Saharan
(or partially Saharan) origin that
flows southward to undercut the
original dust airstream, being thereby
enriched by mixing and by fallout
from above.
Possible Relation of African Dust
to Tropical Disturbances
A great deal of indirect theoretical
and observational evidence exists to
suggest that African dust may play
some secondary role in the growth
or suppression of tropical disturb-
ances and the entire energetics of
the tropical atmosphere. Conversely,
some observations indicate that Afri-
can disturbances have some effect on
the movement of dust into the Carib-
bean and that the behavior of the
dust is at least superficially affected
by the presence of these wave per-
turbations.
Dust as a Nucleator — It is well
known that the size spectra and num-
bers of condensation nuclei have a
profound effect on the population of
water droplets in clouds and the
ability of the cloud to precipitate.
These condensation nuclei are derived
from various types of atmospheric
aerosols — salt particles, dust, pol-
lution, and the like. Much research
has been done both in the laboratory
and in the field, to determine the
nucleating properties of various sub-
stances and their relative importance
in cloud growth.
Similarly, the formation of ice crys-
tals from supercooled water in clouds
depends on the presence of foreign
freezing nuclei and on the distribu-
tion of existing ice crystals. Almost
any substance will nucleate ice at
some temperature, but only a rela-
tively few types of substances are
efficient in this capacity — i.e., are
able to promote freezing at tempera-
tures warmer than about —20° cen-
tigrade. The best-known and most
efficient type of nuclei air crystals is
silver iodide, which has been used in
cloud-seeding experiments. But silver
iodide is not found naturally in the
air in significant quantities. The most
efficient natural ice nuclei are the
clay minerals — notably kaolinite, il-
lite, and montmorillite. These three
minerals are abundant in the soils
of North Africa and have been found
to be a prominent constituent in the
African dust. Since the haze top is
near the freezing level, the dust could
only be effective in freezing if it
were entrained into large cumulus
which protrude to heights well above
the haze top.
Until very recently the Atlantic
trade winds were thought of in terms
192
of a maritime environment in which
aerosol distribution was made up of
sea-salt particles which provide the
clouds with giant hygroscopic nuclei
for condensation and with possible
sites for freezing. The Barbados
measurements, however, show that
the bulk dust density in the air is
greater than the expected concen-
tration of sea-salt particles, even near
the surface. Additional measure-
ments made recently from aircraft
near Barbados show that the ice
nuclei were as high as 10; to 104
per cubic meter in visibly dusty areas,
values that are comparable to those
found over the continents. At other
times, the ice-nuclei concentrations
were found to be negligible in areas
of dense haze. These measurements
suggest that the ice nuclei are deacti-
vated under certain conditions, pos-
sibly by surface contamination with
Aitken nuclei, water droplets, or
some form of pollution.
Such ambiguities in the physics of
ice nuclei and the lack of aerosol
measurements in the tropics preclude
even an educated guess as to the
effect of African dust on the growth
of disturbances. At present, argu-
ments can be made for either sup-
pression or enhancement of cloud
growth given an abundant supply of
aerosols.
Much more evidence is required to
form a quantitative picture of how
much dust is entering the convective
clouds associated with the disturb-
ances and what the distributions are
of ice and condensation nuclei in the
cloud environment and the popula-
tion of ice crystals and water drops
in the clouds. Additional aerosol and
dust measurements need to be made
along the African coast and by air-
craft flying in the vicinity of African
disturbances. A more detailed knowl-
edge of the vertical distribution of
dust and other aerosols should be
sought in these flights. If efforts are
going to be made to seed disturb-
ances, it would be important to know
exactly what the background seeding
capacity of the environment is during
a period of exceptionally high dust
content in order to estimate the seed-
ability of the clouds in these hazy
areas. Aerosol measurements of any
sort made over Africa itself would
be most useful.
Dust as a Tracer of Air Motion —
Besides being an active participant in
the condensation and energetics of
cumulus clouds, the dust is useful as
a tracer of air motions in the trade
winds, thereby leading to an under-
standing- of the dynamics of air mo-
tion at low altitudes. Some tentative
evidence exists showing that the
dust transport off the African coast
is much enhanced by the passage of
an African disturbance south of the
dust-producing area. Intensely hazy
areas, visible on satellite photos, were
concentrated immediately to the rear
(east) of an African disturbance on
two or three occasions in the sum-
mer of 1969. In these particular dust
outbreaks, the leading edge of the
dust mass remained close to the axis
of the easterly wave disturbance as
it crossed the ocean and passed the
island of Barbados. Statistics for the
past three years show that the pas-
sage of African disturbances by
Barbados is accompanied by a sig-
nificant diminution in dust loading
just prior to its arrival and a marked
increase, leading to maximum dust
loading, immediately after passage of
the wave axis by Barbados. It is not
clear whether the disturbance actu-
ally prevents the dust from passing
the wave.
Examination of radiosonde data
shows that the temperature, stability,
and water-vapor content of the air is
singularly different in the dusty area.
In general, air of high dust content
is accompanied by a minimum of
cloudiness. This is probably due to a
more rapid subsidence of the strong
northeasterly trades that are espe-
cially susceptible to the raising of
dust over the continent and to the
increased stability at low levels found
in the dusty air, rather than to an in-
teraction of the dust with the clouds.
Chemical, mineralogical, and
analysis of the dust is another pos-
sible method for determining the
origin, composition, and seeding pos-
sibilities of the dust. This has been
done on a number of selected occa-
sions using the Barbados dust sam-
ples. The results so far are inconclu-
sive, but they do show significant
variations in quartz, calcite, iron, and
other substances between winter and
summer dust. In addition, the lead
and zinc content of the summer dust
is anomalously high, especially in
comparison to the very low amounts
of these elements in the winter dust.
These two elements owe their abun-
dance to industrial contamination,
notably fossil fuels. Therefore, the
air that carried the dust from the
northwestern corner of the Sahara
was likely to have been over indus-
trial Europe immediately before its
arrival over Africa; conversely, the
winter dust is carried in an airstream
of long-standing duration in the
tropics.
Measurement Techniques and
Their Implications
Radon-222 — Some indirect meas-
urements of dust content can be made
using radon-222 as a tracer of Sa-
haran dust. Radon-222 is liberated
from soils in large quantities and is
mixed throughout the lower layers
of the atmosphere in much the same
way as water vapor and dust are
mixed from their sources at the
earth's surface. Unlike dust, how-
ever, radon gas is not washed out by
rain. This property (insolubility) can
provide a means of studying the
washout of dust and the later move-
ment of Saharan air after it has
passed through a cycle of cumulus
convection.
Thus, radon-222 measured in the
high troposphere may be useful in
tracing the outflow of dusty air from
the tops of cumulonimbus and can
lead to a substantiation of the theory
that the high concentrations of ice
nuclei and dust particles sometimes
193
PART VI — PRECIPITATION AND REGIONAL WEATHER PHENOMENA
found in the upper atmosphere are of
terrestrial origin. Radon measure-
ments in the southern hemisphere
south of the North Atlantic trade
winds can provide valuable informa-
tion on cross-equatorial flow and the
flow of air across the Intertropic
Convergence Zone.
In one aircraft expedition made by
a U.S. research team flying between
Miami and Dakar, a high correlation
was found between haze and radon
activity. This relationship between
dust and radon activity was substan-
tiated in further aircraft flights made
near Barbados in I^b® and by some
measurements made on board the
US5 Discoverer the same year. Radon
was also measured south of the equa-
tor on the flight. More such flights
and expeditions are needed to expand
our fragmented knowledge of dust
transport.
LIDAR — Another indirect method
for estimating the vertical distribu-
tion of dust is with LIDAR, which
measures the back-scatter from a
laser beam. However, back-scatter
measurements are highly dependent
on particle size and are extremely
difficult to interpret in terms of dust
distribution without supporting data
to accompany them.
Turbidity Measurement -- More
useful than LIDAR in the study of
dust is the measurement of turbidity
from photometric measurements of
skylight distribution and spectral at-
tenuation of solar radiation. These
turbidity measurements can also be
compared with atmospheric back-scat-
ter and albedo as determined from
satellites. Atmospheric dust over the
tropical Atlantic can have an im-
portant effect on the energy balance
of the tropics and, consequently, on
the global circulation. Since the at-
mospheric turbiditv is a function of
the aerosol content of the air, the
total incoming and outgoing radia-
tion and the changes in absorptivity
and emissivity on the vertical can af-
fect the heating and the convective
instability of the trade winds. There
is some evidence that the growing
pollution over the earth during the
past few decades has resulted in an
increase in atmospheric turbidity and
a slight decline in worldwide tem-
perature. An increase in turbidity at
low latitudes can effect a decrease in
worldwide temperature and a slowing
down of the general circulation of the
whole earth. At present there is
some question as to the cause of the
turbidity increase over the years. It
may actually be due to natural causes
such as volcanic eruptions or changes
in dust content of the air rather than
to industrial pollution. Since sig-
nificant changes in dust loading from
year to year do occur in the Atlantic
trade winds (the amount of dust
reaching Barbados in the summer of
1969 was double that in the previous
four years of record), it would there-
fore be useful to measure turbidity in
the Atlantic trade-wind area on a
yearly basis in order to determine the
natural fluctuation in the components
of the radiation balance there.
African dust may thus influence
tropical storm development indirectly,
by means of its capacity to alter the
long-term thermodynamics of the
tropical environment.
194
PART VII
WATER RESOURCES,
FORESTRY, AND
AGRICULTURE
1. WATER RESOURCES
Estimating Future Water Supply and Usage
Most estimates of water supply
and usage have been couched in terms
of average annual water supply and
projected usage at some future date.
For small areas within the scope of
a single project or a system of proj-
ects, water supply is sometimes stated
as the mean flow available during
the most critical dry period in the
record. Such assessments have the
virtue of simplicity and are reason-
ably well understood by the layman.
At the national level, a statement
of mean water supply and mean
usage is probably entirely adequate
because water-supply problems are
never solved at that level. At the
regional and local level, however,
use of the mean supply available
and a projected future usage deprives
the planner of the opportunity for
strategic evaluation of alternatives.
The planner is concerned with sup-
plying water for a specific period of
years into the future. It is virtually
certain that the actual streamflows
during this future period will not
duplicate those of the historic past
and that water usage at the end of
the period will not precisely equal the
forecast. Faced with such uncertainty,
the planner would be wise to treat
both variables in terms of probability.
Only through a probabilistic treat-
ment can he evaluate the risk of
expanding water-supply facilities too
fast, with consequent excessive costs
and risk of losing future technologi-
cal advantages, or of developing a
system so slowly as to threaten a
serious water shortage at some future
date.
Estimates of Water Supply
The data base for estimates of
water supply consist of approxi-
mately 10,000 gauging stations oper-
ated mostly by the U.S. Geological
Survey; in addition, many thousands
of wells provide information on
groundwater levels. There may be
specific local deficiencies in this data
base, but on the whole it must be
judged reasonably adequate. It is
fortunate that this base exists, be-
cause only time can remedy deficien-
cies — from 30 to 100 years of record
are required to describe statistically
the characteristics of water supply.
Qualifying Factors — Interpretation
of existing data on streamflow and
groundwater is complicated by the
fact that few stations record virgin
conditions. Regulation by reservoirs,
diversion from streams, pumpage
from groundwater, alteration of
stream channels, vegetation-manage-
ment practices, urbanization, and
many other factors render available
data series inhomogeneous over time.
In some cases, the effect of man's
activity is rather accurately known
and appropriate corrections can be
made. In most instances, however,
only the sign of the change can be
stated with accuracy.
Synthetic Streamflow Records —
The last decade has seen the devel-
opment of hydrologic simulation us-
ing both digital and analogue com-
puters. Simulation is capable of
transforming precipitation data into
synthetic streamflow records. Simu-
lation brings many thousands of
precipitation stations operated by the
National Weather Service into the
data base and makes it possible to
make streamflow estimates at sites
where no gauging station exists. Be-
cause precipitation records are gen-
erally longer than streamflow records,
simulation permits the extension of
flow records at currently gauged sites.
Similar development has taken
place with respect to simulation of
groundwater basins primarily through
the use of analogue models. Al-
though these models cannot perfectly
reproduce historic streamflow or
groundwater basin performance be-
cause of errors in the data inputs
and deficiencies in the models them-
selves, errors in model outputs are
generally random and pose no serious
problem in probabilistic estimates of
water supply. Simulation models also
permit adjustment of observed flows
or groundwater levels to virgin or
natural conditions. It may be con-
cluded, therefore, that we are now
able to combine observed and syn-
thesized data into a data base cover-
ing a sufficient period of time to de-
fine the mean and variance of water
supplies with reasonable accuracy.
Problems of Data Projection — The
historic data base, observed or simu-
lated, does not fully satisfy the need
for projections of future water sup-
ply, however. The water-supply
planner is concerned with possible
events over a specific period ranging
from 20 to 100 years in the future.
He is particularly concerned with
the sequences of annual flows, be-
cause a series of consecutive dry
years will impose a much greater
burden on his reservoir (surface or
subsurface) than the same number
of dry years dispersed over his plan-
ning horizon. To meet this problem,
the field of stochastic hydrology has
developed during the 1960's.
Stochastic Hydrology — In stochas-
tic hydrology, generating functions
derived from the estimated statistical
characteristics of the historic record
are used in conjunction with random
numbers to generate many possible
flow sequences. Thus, a thousand
years of stochastic streamflow can
be broken into ten 100-year periods,
from which the planner can estimate
197
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
the probability that a proposed reser-
voir will be adequate against any of
these ten alternative futures.
Streamflow is inherently more vari-
able than precipitation and it is fair
to assume that we know the statisti-
cal parameters of precipitation with
greater accuracy than those for
streamflow. It follows that the
stochastic generation of precipitation
data should be a more certain process
than stochastic generation of stream-
flow data. Stochastically generated
precipitation data can be converted
to streamflow by deterministic simu-
lation models, although the process
would be substantially more expen-
sive than direct stochastic generation
of flow data, since deterministic
simulation is inherently more com-
plex and time-consuming. Preliminary
work on stochastic generation of
rainfall has recently begun, but fur-
ther research should be encouraged.
The Relevance of Climate — In
addition to the stochastic properties
of future streamflow, a number of
other issues arise before the planner
can be content with his projections
of future water supply. The first of
these is the question of long-term
climatic trends. An abundance of
data demonstrates the existence of
such trends in terms of geologic time
and in terms of periods as short as
a few hundred years. However, no
sound basis exists for predicting the
existence of a trend and its conse-
quences over the next century. Cli-
matic trends could alter the water-
supply outlook in arid and semi-arid
regions, since the hydrologic balance
is sensitive to small changes in pre-
cipitation input or evapotranspiration
outgo. Techniques that could iden-
tify causes and project trends, even
in an approximate fashion, would be
extremely valuable to the water-
resource planner.
The Relevance of Human Activ-
ity — In addition to natural climatic
trends, future water supplies may
be affected by man-induced changes,
both intentional and inadvertent.
Intentional changes include those
brought about by land-management
practices, vegetation management, de-
salinating of brackish or saline wa-
ters, or effective reclamation of waste
water. The question that confronts
the planner is "Will any of these
become practically useful and if so
when?" The issue is the evaluation
of probable rates of technological
advance. It will be seen that similar
questions arise in the discussion of
water usage.
Inadvertent changes in water sup-
ply may be brought about by urban-
ization, which increases surface runoff
and decreases infiltration to ground-
water. If one can make reasonable
projections of future urban growth,
deterministic hydrologic models can
project the alterations in streamflow
and accretion to groundwater. More
subtle are the effects of air pollution,
urbanization, and changes in land
use and vegetative cover as they
may affect climate. These possibilities
underline the importance of research
on climatic change.
Estimates of Water Use
The problem of predicting future
water use is far more complex than
that of predicting water supply, if
only because of the much larger
number of components that must
enter the forecast. It is convenient
to divide the discussion of water
use into the requirements for the
several purposes to which water is
most commonly applied. Before each
of these purposes is discussed, how-
ever, two general topics should be
noted.
General Considerations — First, the
distinction between diversion and
consumption should be underlined.
For many purposes, large quantities
of water are diverted for use but only
a small fraction of the diverted water
is consumed; the rest is returned
to the environment — sometimes de-
graded in quality. (See Figure VII-1)
An outstanding example is the use of
water for cooling in industry and
power generation, which actually con-
sumes very little water; most of the
water used is returned to a stream
or to the groundwater substantially
warmer than when originally diverted.
Because of the re-use aspects, dis-
cussion of diversion requirements is
confusing. Here we will consider
only consumptive use. Consumptive
use is defined as that portion of the
water which is evaporated or com-
bined in the product so that it is no
longer available for re-use in the
original source system.
A second topic which deserves
consideration on a general basis is
that of population forecasting. For
nearly all water uses, estimates of
population and its geographic dis-
tribution are fundamental. If prob-
ability estimates of future water use
are to be derived, they must begin
with estimates of probable future
population. Research has been done
on the variance of population esti-
mates as indicated by statistical eval-
uation of historic predictions. A
more fundamental study might ex-
plore the uncertainties in each of
the factors involved in population
forecasting.
The most difficult problem is the
forecasting of local population by
county or city units. Factors that do
not enter national population fore-
casting are involved in predictions
of the distribution of population.
Not the least of the factors that may
affect future distributions is govern-
ment policy concerning desirable
population distribution. Some re-
search on the optimal size of popu-
lation concentrations may be useful.
Is there a city size at which the
unit cost of infrastructure is mini-
mized? What are the advantages of
population dispersal against increased
growth of major metropolitan cen-
ters?
Domestic Water Use — The ques-
tion of domestic water requirements
depends largely on two issues. One
198
Figure VI 1—1 — DISPOSITION OF WATER DIVERTED FOR IRRIGATION
Evapotranspiration
from Crop Area
Evaporation
before returning
Water Resource
Pool
The diagram shows schematically what becomes of water diverted for irrigation
purposes in the U.S. The width of the stream represents the relative quantity of
water moving in that path. Water is consumed by evaporation from various sources
and evapotranspiration from irrigated areas. This reduces the water supply available
for sequential uses. The non-consumptive paths such as seepage, runoff, and perco-
lation return water to the resource pool, leaving it available for subsequent uses.
This return water may improve or degrade the water quality depending on the initial
quality of the water, the uses to which it has been put, and the particular character-
istics desired by the sequential users.
is the technology of water use. Plan-
ners have generally assumed a slow
increase in per capita water require-
ments. It should not, however, be
exceptionally difficult to redesign
conventional plumbing fixtures and
water-using appliances so that water-
use rates are reduced without sacrific-
ing the amenities of present users.
The second factor that might sig-
nificantly affect domestic consump-
tion would be changes in life styles.
A shift from dispersed single-family
residences to multi-family residences
would be the most significant change.
Savings in water would be achieved
through reduction in lawn and garden
water requirements. Changes of this
kind are probably closely related
to technology through construction
costs, transportation techniques, dis-
position of leisure time, and public
policy with respect to taxation. Sub-
jects for research on the impact of
technology on society in this area are
abundant.
Industrial Water Use — The aver-
age values of industrial water use per
unit of product produced are ex-
tremely large in many industries.
There are, however, many opportu-
nities for reducing water use by re-
cycling, recovery of by-products, and
other techniques. Estimates of future
industrial use are dependent on esti-
mates of future industrial production
and the extent to which water-
conservation techniques are applied.
Water in Agriculture — The largest
water-using sector in the United
States today is irrigated agriculture.
In states like California, over 90
percent of the water use is for irriga-
tion. Future agricultural water re-
quirements are therefore extraordi-
narily important. Unfortunately, they
are difficult to assess. What are the
future needs for food and fiber
production? How much food and
fiber will the United States produce
for export? How much can food and
fiber production in the humid eastern
states be expanded? How can water-
use efficiency in agriculture be im-
proved? What is the possibility of
breeding crop types requiring less
water or capable of using brackish
water instead of fresh water? To what
extent will it be possible to raise
crops in arid regions in controlled
environment chambers? Will exten-
sive, low-cost greenhouses in which
water use can be carefully controlled
become technically feasible? These
questions all involve issues of tech-
nical feasibility, extent to which
efficiency of production can be im-
proved, and time-rate at which these
developments can be expected.
Energy Production — The consump-
tive water requirements for the pro-
duction of electric energy are rela-
tively small. A hydroelectric power
plant actually consumes only small
amounts of water evaporated from
the reservoir surface. A thermal plant
consumes the water evaporated in
cooling the condensers. If predictions
that power demands will continue to
double every decade (thousand-fold
increase in 100 years) prove accurate,
however, the current relatively small
use will grow rapidly into a major
source of water consumption.
Again, the projection of water re-
quirements for power production
raises mainly technological issues.
What are the prospects for new types
of thermal power producers for which
cooling- water requirements are less?
Are there possibilities of cooling
methods that are less demanding on
the water resource? Use of heated
condenser water for irrigation shows
promise of minimizing the "thermal
pollution" of streams and improving
the efficiency of irrigation. Not all
thermal power plants can be situated
close to potential irrigated areas,
however. What other uses of waste
199
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
heat may be feasible? Is it conceiv-
able that per capita power require-
ments may be reduced by reducing
power requirements in the home and
industry? Can climate control be
achieved? Will future urban centers
require less energy and water for
airconditioning?
Navigation — Navigation is not an
extremely heavy user. Evaporation
losses from reservoirs from which
water is released to maintain navi-
gable depths downstream constitute
the primary consumptive use. The
quantity is probably so small that
it deserves little consideration as com-
pared with other demands on our
water resource. However, it is appro-
priate to ask what future transporta-
tion technology may be expected.
Will relatively slow, bulk transport
by water continue to be a favored
procedure? Will high-speed surface
or air transport encroach on the
market for bulk transport to the
point where future expansion of navi-
gation facilities may stop?
Recreation — Like navigation, rec-
reation is not presently a heavy con-
sumer of water. Primary water use
by recreation is evaporation from
reservoirs constructed solely for wa-
ter recreation or from an increased
water surface area in reservoirs be-
cause of projected recreation. It is
unlikely that reservoirs will be built
solely for recreational purposes in
water-short areas. Recreation does
not appear to be a factor of great
uncertainty with respect to future
water use. However, it may be ap-
propriate to mention here the pos-
sibility of evaporation suppression
from water surfaces by the use of
film-forming chemicals or covers. If
successful techniques for evapora-
tion suppression could be achieved,
requirements for many of the uses
discussed above could be reduced.
Fish and Wildlife — It is currently
accepted that the maintenance of
fish and wildlife requires that a con-
tinued flow be maintained. A sub-
stantial part of this flow is eventually
discharged into the oceans where it
can no longer be used. Water re-
quirements for this purpose are
surely not well known. The mech-
anisms by which a reduction in dis-
charge into estuaries may affect
marine life need to be established.
This need derives from two com-
peting aspects. We need to know
how much water must be permitted
to flow to the oceans in order to
maintain fisheries for both economic
and sports purposes, and the extent
to which this fresh-water flow in-
fluences other estuarine and oceanic
resources. We also need to know
the consequences of excessive flood
flows through estuaries. Are such
flows beneficial or detrimental? In
addition to the consequences for fish-
eries and wildlife, what are the effects
of regulating streamflows to the
ocean on sediment deposits in es-
tuaries and harbors and on nourish-
ment of beaches?
In summary, probability estimates
of water supply are limited only by
hydrologic understanding, and solu-
tions appear to be close at hand.
Projections of water usage are heavily
dependent on projections of new
technology. Little effort has been
devoted to this latter problem and,
therefore, current projections of use
are quite uncertain.
Water Movement and Storage in Plants and Soils
Since only five feet of soil can
generally store fully ten inches of
precipitation and since evaporation
from soil and foliage returns to the
air about 70 percent of our precipi-
tation, these two factors represent a
significant portion of the hydrologic
cycle and a determinant of our water
resources. (See Figure VII-2) Further,
and less often noted, the relations of
precipitation, evaporation, and stor-
age will determine the escape of
soluble substances such as nitrate
from the region of roots and into
groundwater and streams.
Because the plant roots are inter-
twined among the soil particles and
water flows readily from one to the
other, plant and soil — and, for that
matter, the atmosphere as well — -
must be analyzed as a continuous
system. Then the components can
be examined in order of their impact
on the system, and the results used
to improve our understanding and
ability to predict the functioning of
the entire system outdoors. Fortu-
nately, our ability to cope with the
entire system has been advanced
materially in recent years.
Total Evaporation
Essentially, the soil-plant-water
problem is to measure the extraction
from the soil, conduction to the
leaves, and then evaporation from
the leaves. Some water may short-
circuit this path and be evaporated
from the soil or leach beyond the
roots, but a lot — often most —
takes the route of soil to plant to air.
Evaporation from the Canopy —
Recently, research has greatly im-
proved our understanding of how
water gets from the canopy of foliage
to the atmosphere above. When
evaporation from the canopy strata is
viewed as a factor in an energy
budget and evaporation and convec-
tion are set proportional to tempera-
ture and humidity differences, the
evaporation (and the temperature and
humidity of the air within the canopy
microclimate) can be calculated from
the weather above and below the
canopy, the profiles of radiation and
ventilation, the distribution of foliage
area, and the boundary layer and
stomatal resistance of the foliage. In
200
RCES
Figure VII-2 — THE HYDROLOGIC CYCLE
\d,
EVAPORATION FROM THE SEA
367
Domestic and
Industrial needs
(Units of measure in cc)
S — Surface Runoff
P — Percolation
U— Uptake
R — Residual
This is an idealized version of the water cycle. The numbers attached to the various
processes are relative units of measure. Note that the truly important parts of the
cycle are evaporation from the sea, precipitation, and evapotranspiration.
1956, Penman showed how evapora-
tion from abundant foliage suffici-
ently wet to have wide stomata could
be calculated from the net all-wave
radiation available above the canopy.
The recent advance is, therefore, in
understanding how foliage condition
can decrease evaporation below Pen-
man's potential and how the evapora-
tion and consequent temperature and
humidity within the canopy are
changed. The total evaporation from
the canopy, according to our new
understanding, is affected profoundly
by the leaf area and, more subtly, but
still considerably, by the stomatal
conductivity or porosity of the foliage
for water.
Future Observations and Experi-
ments — This understanding has been
arrived at by means of mathematical
simulation. To make a substantial
improvement in our understanding —
or even to test our present under-
standing — future measurements of
evaporation from crops and trees
must include observations of leaf
area and porosity as well as weather
and evaporation. Fortunately, since
the invention of a simple, portable
porometer by Wallihan in 1964 and
the subsequent calibration of several
modifications, porosity can easily be
measured.
Earlier hydrologic observations sug-
gested that different vegetation con-
sumed different amounts of water
in evaporation. The simulators men-
tioned above, along with experiments
with sprays that shrink stomata, have
now established that evaporation can
be changed by modest changes in
the canopy. During the coming years,
therefore, one can expect a variety of
experiments seeking the most effec-
tive and least injurious ways of con-
serving water in the soil through
treating or modifying the vegetation.
Microclimatic Measurements
Turning to the distribution of
evaporation, temperature, and hu-
midity within the canopy — in con-
trast to the sum of evaporation
discussed above — one finds that a
greater number of parameters can
be effective. The changes in tem-
perature and humidity along the path
conducting water and sensible heat
out of the canopy depend on the
boundary layer around the leaf and
the turbulence of the bulk air within
the canopy. These two factors gen-
erally are of smaller magnitude than
the stomatal resistance and hence
are relatively ineffective, we believe,
in changing the sum of evaporation.
However, when we turn to the
distribution of temperature and hu-
midity within the canopy — the mi-
croclimatic question — these param-
eters are influential. Scientists do
not yet know how to measure them,
however.
Boundary-Layer Resistance — For-
merly, this was estimated from a
conventional fluid mechanics equa-
tion, employing the square root of
leaf dimension divided by wind
speed. Recently, however, Hunt and
201
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
others have claimed that this estimate
is greater than the true resistance
within a canopy. Presumably, this
question can be resolved by fluid
mechanics, energy budgets, and the
new porometers.
Diffusivity Within the Canopy —
This is harder to measure. At present
it is estimated by measurements
of radiation absorption and tem-
perature and humidity gradients.
The method is susceptible to error,
produces estimates at variance with
the wind speed and employs the very
temperatures and humidities that one
would like to predict. A new method
of estimating diffusivities within the
canopy is required but none has yet
appeared.
Microclimatic observation will un-
doubtedly continue in the future. If
the observations are to be most useful
in testing and improving our under-
standing, they should include the ver-
tical variation in leaf area and poros-
ity as well as radiation, temperature,
humidity, and ventilation. Since this
makes a formidable list of equip-
ment and tasks before a complete,
and hence worthwhile, set of ob-
servations can be made, microclimatic
and evaporation studies seem ideally
suited as testing grounds for coop-
erative or integrated teams of sci-
entists.
Horizontal Heterogeneities — The
final remark concerning the aerial
portion of the problem must concern
horizontal heterogeneity and advec-
tion. Chimneys and sun flecks among
the foliage clearly render our ideal,
stratified models unrealistic. There-
fore, efforts to incorporate these
heterogeneities into the analysis are
welcomed, even if they only prove
that the ideal, homogeneous model
gives the same average evaporation
and microclimate as the realistic
model.
The larger heterogeneities con-
noted by "advection" are known to
be important, justifying the term
"oasis effect." Advection of carbon
dioxide has already been treated
simply in a photosynthesis model,
and incorporating large-scale advec-
tion into the existing evaporation
models seems manageable and worth-
while.
Water Storage in Soil
The transport of water to foliage
from soil has not yet been mentioned.
Relatively less can be said about it
in a systematic way. As a comple-
ment to the simulation of evaporation
from foliage, we need a comprehen-
sive simulator of this portion of
the path of the water that will tell
us how much water gets to the leaves
and, more important, how stomatal
resistance is modified. The simulator
concerning soil and plant is more
lacking in foundation than one con-
cerning plant and air. Nevertheless,
beginnings have been made by Cowan
and Raschke.
Gaps in Scientific Understanding —
These primitive simulators reveal se-
rious deficiencies in our understand-
ing of (a) the relation between water
potential in the leaves and stomatal
resistance; (b) the conductivity of
different root regions; and (c) the
conductivity between soil and roots.
This last matter includes the dif-
ficult problem of root distribution
through the soil profile. The actual
storage capacity of the soil and rela-
tion between potential and content
seem fairly well established. The
effect of changes of temperature in
time and depth is yet to be coped
with.
New instruments usable in the
field should help. The new porom-
eters have been mentioned already,
and the Scholander pressure chamber
promises to reveal water potentials,
even in roots. We are still left, how-
ever, to search for root distributions.
In the case of temperature differences,
on the other hand, the problem is
to improve our logic rather than our
observations.
The next problem is the escape of
water from soil storage via a moist
surface or by leaching rather than
through vegetation. These two es-
capes greatly affect the loss from the
root zone of salts and nutrients that
pollute the water below. Evaporation
and land leaching from the soil have
been measured carefully in bare soil,
but the present challenge is to under-
stand the parameters sufficiently well
to estimate them when a canopy of
foliage is also removing water. This
is a fundamental problem of the
movement and loss of water from a
heterogeneous porous medium with a
variable and heterogeneous tempera-
ture. The research of the past has
not brought us a lucid understanding
of the system; at present, progress
seems most likely to come from de-
vising a better logical framework on
which to hang our measurements.
A Final Word
The reader may have noticed that
time has not been mentioned. That
is, analyses or simulators of an in-
stant only have been described. In-
tellectual satisfaction and eventual
utility requires that our understand-
ing and predictors be extended
through time, with the storage of
plant and soil as parameters.
202
I
A Note on Subsidence and the Exhaustion of Water-Bearing
and Oil-Bearing Formations
Virtually all rocks near the earth's
surface are to some degree porous,
and if water is available it fills the
pores. In some rocks the pores are
large enough and well enough inter-
connected so that water can readily
flow from volumes of higher pres-
sure to volumes of lower; such rocks
are called aquifers — water bearers.
Other rocks have pores so fine and
so poorly interconnected that water
passes through them only slowly,
even under high pressure-gradients;
these are aquitards — water-retarders.
Among the common rocks, sand-
stones, conglomerates, cavernous
limestone, and scoriaceous lavas are
the chief aquifers; shales are the
principal aquitards.
Subsidence
Where water has access to an inter-
bedded series of aquitards and aqui-
fers both are commonly saturated,
but the aquitards are sufficiently im-
permeable as to permit considerable
pressure differences to exist between
the several aquifers. When a well is
drilled to any particular confined
aquifer and water is withdrawn from
it, the water pressure in the aquifer
is decreased and the aquifer shrinks
in thickness. The weight of the
rocks overlying the aquifer, which
had formerly been in part sustained
by the pressure of the contained
water on the base of the overlying
aquitard, has become effectively
greater because of the decrease in
hydrostatic pressure; under the ef-
fectively greater load, the aquifer
yields elastically and the volume of
its pores diminishes.
Though Young's modulus for most
sandstones is between 140,000 and
500,000 pounds per square inch, a
significant pressure reduction in an
aquifer several hundred feet thick
can readily cause a subsidence of
several feet at the surface of the
ground. Such a subsidence may cre-
ate serious problems in drainage, sew-
age disposal, and utility maintenance.
More important than simple elastic
compression of the aquifers, how-
ever, is the fact that the lowered
pressure in the aquifers permits slow
drainage into them from adjoining
or interbedded aquitards. This per-
mits the aquitards also to be com-
pressed by shrinking their pore
spaces.
Thus, at the Wilmington oil field,
in California, the loss of pressure
in the oil sands after 1936, when
production on a large scale began,
led to a surface subsidence of more
than 32 feet (see Figure VII-3) before
recharging of the oil sands with sea
water under pressure finally stabilized
the surface. Of this subsidence, only
about 10 feet could be attributed to
elastic compression of the oil sands;
the remaining 22 feet was almost cer-
tainly due to de-watering of the asso-
ciated shales. The cost of this sub-
sidence was many millions of dollars,
since the railroad terminals, docks,
shipyards, drydocks, and power
plants had all to be rebuilt, together
with the streets, water, and sewer
systems of a large part of the city
of Wilmington.
Similar subsidence caused by with-
drawal of fluids under pressure has
been noted at many other seaside
localities: Lake Maracaibo, Vene-
zuela; Goose Creek, Texas; Hunting-
ton Beach, California; Redondo Beach,
California. None caused as great a
loss as that at Wilmington.
It is possible for similar subsidence
to pass unnoticed at areas inland be-
Figure VII-3 — SUBSIDENCE IN LONG BEACH, CALIFORNIA
(Illustration Courtesy of the Geological Society of America )
Superimposed on the photograph of the port area of Long Beach, California are
contours of equal subsidence in feet as they existed in 1962. The subsidence in
the upper right resulted from withdrawal of fluid from the Signal Hill oil field be-
tween 1928 and 1962. The major subsidence in the foreground was due to with-
drawal from the Wilmington oil field.
203
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
cause a definite reference surface is
not obvious. Nevertheless, the failure
of the Baldwin Hills Dam in western
Los Angeles, with the loss of many
lives and millions in property damage,
was probably due to withdrawal of
fluids from the underlying oil field.
The subsidence of many feet beneath
the city of Mexico was caused by
withdrawal of water from the lake
sediments on which the city was
built; considerable expenditures have
been needed to take care of drainage
disposal.
Two other areas in California have
suffered large losses through with-
drawal of water from beneath. In the
Santa Clara Valley, pumping of water
from a confined aquifer at depth has
led to subsidence as great as 9 feet
between 1934 and 1959 in the city
of San Jose; subsidence has also
been considerable farther north in
the valley, including such important
industrial areas as Sunnyvale.
On the west side of the San Joa-
quin Valley, dewatering of surficial
sediments had caused the surface
to subside as much as 23 feet by
1963 and forced alterations in the
plans for the new irrigation system
now under construction.
Exhaustion of Groundwater
Most of the agricultural produc-
tion of the High Plains of Texas and
eastern New Mexico tributary to the
cities of Lubbock, Amarillo, and Por-
tales depends on water pumped from
the Ogallala Formation, of Pliocene
age. The Ogallala is composed of
gravel and sand that was deposited
as a piedmont fan from the Rocky
Mountains to the northwest. Erosion
since its deposition has cut deeply
enough to sever the connection with
the mountain streams whose sedi-
ments led to the formation. The result
is that water pumped from the forma-
tion is not being recharged from
the mountains; the small amount of
recharge that feeds into the under-
ground reservoir is simply seepage
from the overlying arid surface. Es-
timates by the Texas Agricultural
Experiment Station were that re-
charge amounts to only about 104,000
to 346,000 acre feet of water for
the Texas portion of the High Plains,
whereas pumpage averaged 5 million
acre feet during the period from
1954 to 1961. Obviously, the water
table is sinking at a tremendous
rate, ranging from 1.34 to as much
as 3.72 feet per year, and the cost
of pumping is rising accordingly.
The water is being mined, just as
literally as is coal from a coal seam,
and a drastic change in the economics
of the region is unavoidable.
The Texas study projects the de-
cline in irrigated acreage from 3.5
million acres in 1966 to 125,000 acres
in 2015. Cotton production is ex-
pected to decline from about a million
bales in 1966 to 355,000 bales in
2015, of which 70 percent will be
grown on dry land. At 1966 prices,
the aggregate annual value of agricul-
tural production is projected to de-
cline 70 percent in fifty years. Drastic
economic change is clearly in sight,
not only for the farm operators but
for suppliers of farm machinery, auto-
mobiles, and other inputs into agri-
culture. Urban decline is also in-
evitable.
Water is being mined at many
other places west of the 100th merid-
ian — notably in the Mojave Desert
of California and many of the inter-
montane valleys of the Basin and
Range Province in Arizona, Cali-
fornia, Nevada, Utah, and Oregon.
In each of these, results comparable
to the inevitable decline of the High
Plains are foreseeable, though the
rate of decline will vary from area
to area.
204
2. FORESTRY
Water Quality in Forests
Lands classified as forest, approxi-
mately three-quarters of them in
private ownership (see Figure VII-4)
make up almost exactly one-third of
the total land area of the United
States. A large portion of this is well
supplied with precipitation, and the
excess over that lost by evapotran-
spiration is the source of much of the
water reaching streams, lakes, and
ground waters.
Water issuing from essentially un-
disturbed forests, even those on steep
terrain or with thin or erosive soils,
is ordinarily of high quality — low
in dissolved and suspended matter
except during major floods, high in
oxygen content, relatively low in
temperature, and substantially free
of microbial pollutants. These qual-
ities are desirable and highly visible
to recreational users of these lands,
and some are absolutely essential to
fish such as trout and salmon. They
are also highly important to down-
stream users, whether agricultural,
urban, or industrial. In addition to
any legal rights these users may have
acquired to water volume, they of-
ten have built-in dependencies — aes-
thetic, technical, or economic — on
quality features; they are commonly
prepared to resist any real or prospec-
tive impairment, regardless of the
interests of the owners of the lands
from which the water comes or other
social claims on its use.
Nevertheless, these water-yielding
lands are required for a variety of
other goods and social purposes —
timber, recreation in many forms,
grazing and wildlife production. A
very large proportion of public and
private land is held especially for
such uses, whereas only rarely is
there any direct recompense to the
landholder for the outflowing waters.
Despite contrary advocacy, it will sel-
dom be defensible to propose water
quality as the exclusive goal of forest
land management over large areas.
Now, all uses, all manipulation of
soil and vegetation, pose some poten-
tial risk to water quality — sometimes
major, sometimes trivial. Even wild-
erness camping, construction of roads
essential for adequate fire protection,
or forest cutting or herbicide treat-
ments to reduce transpiration and so
increase water yield conceivably could
affect water quality adversely. Ac-
cordingly, conflict between absolutely
unaltered water quality and other
land uses will likely be inevitable
at times, and may have to be resolved
on economic or political grounds.
Moreover, conflicts between compet-
ing land uses — as forage versus
timber, large game versus domestic
animal grazing, industrial raw ma-
terials versus scenic impact — may
be resolved on grounds other than
water quality.
But there is abundant evidence —
chiefly from U.S. Forest Service ex-
perimental watersheds — to demon-
strate that other uses of watershed
lands either already are or can be
made compatible with essentially un-
impaired water quality. A variety of
techniques and constraints will be
needed, such as where and how roads
are built, the nature and timing of
silvicultural or harvesting practices,
how recreationists travel and camp.
Many of these are known already;
others are under investigation; still
Figure VII-4 — OWNERSHIP OF U.S. FOREST LANDS
The diagram shows the forest ownership pattern in the U.S. in 1952. Federal, state,
and local governments owned only 27 percent of the forest land. An additional
13 percent was under the control of forest industries. Such a situation makes forest
management difficult because many private owners lack the incentive, knowledge,
or interest to use approved forestry practices on their lands.
205
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
others must be devised. In a few
fragile landscapes only limited ac-
cess and use may be allowable.
There can be no simple, universal
prescriptions for reconciling conflict-
ing uses with each other or with
water quality. The land classified as
forest comprises an enormous number
of combinations of vegetation types,
soil and bedrock characteristics, land-
forms and slopes, and climatic re-
gimes. The latter include variation
in total precipitation, its distribution
and intensity on the watersheds, and
features such as snowpack accumula-
tion. This great number of combina-
tions prevents easy generalization of
studies on one watershed to others
with different soil, slope, or precipi-
tation features. It also emphasizes
the need for much better charac-
terization data — climate, geology,
hydrology, and soils — for many
important watershed regions, for in-
vestigation of predictive models, and
for expansion of on-the-ground
"adaptive research" aimed at convert-
ing principles discovered thus far into
locally feasible guides for day-to-
day operation.
Factors Affecting Water Quality
To a considerable degree, water
quality has always figured in a larger
concern with the protective function
of forest cover upon stream flow —
that is, flood control, water yield,
and watershed maintenance or im-
provement. The same natural or
man-induced features that make for
low infiltration rates, rapid surface
runoff, and reduced storage in the
soil mantle also lead variously to
higher flood peaks but reduced flows
in low water periods, to surface ero-
sion and channel cutting, to sedimen-
tation of downstream channels and
empoundments, and to high turbidi-
ties and sometimes high contents of
material swept from the soil surface.
Thus, turbidity and sediment content
are valuable indices of impairment
or improvement of the protective
function of watershed, in addition
to being direct measures of water
quality.
Water "quality" is a nebulous fea-
ture until described in terms of spe-
cific attributes such as turbidity, or-
ganic content, temperature, nitrate,
phosphate, pesticide or other chemical
content, and bacteriological quality.
These are sometimes discussed as
considerations of equal probability,
hazard, and rank, but in fact, turn
out to be far from equivalent in any
respect.
Temperature and Oxygen — Re-
moval of trees or brush greatly in-
creases direct radiation to small
streams and materially raises maxi-
mum temperatures in the warm sea-
sons— up to 7 to 8 centigrade
higher, according to some studies.
Such increases may be unfavorable
or lethal to desirable fish, especially
to salmon and trout species which
spawn in small headwater streams,
and they also contribute to higher
average temperatures of downstream
waters. The physical basis of this
effect is fairly straightforward, of
course, and the temperature in-
crease of small streams has been
predicted quite accurately through
use of an energy-balance technique.
Experimental observations are lim-
ited and there can be no generaliza-
tion about the importance of this
effect to quite different climate and
ecological regions. Within the Pacific
Northwest, however, knowledge of
temperature increase and oxygen de-
crease following removal of cover
is sufficient to call for protection of
spawning waters.
A highly effective management
remedy is to leave narrow strips of
live vegetation for shade; such strips
are also important safeguards against
stream or bank disturbance by log-
ging operations. Such remedies may
entail substantial sacrifice of timber
values, as well as higher costs for
harvesting and regeneration, and ap-
plication may well hinge on benefit/
cost analyses. Further, one can fore-
see occasional instances of con-
flict between retention of shade and
decreased water temperature on the
one hand, and efforts to increase
low water flow through reducing
vegetation in the riparian zone on
the other.
Pesticides — A number of plant-
protection or plant-control chemicals
have been applied to forest vegeta-
tion, and the need for such agents
will certainly continue even though
particular classes of compounds, such
as chlorinated hydrocarbons, are
banned. Reduction of losses during
major insect outbreaks, control of
competing vegetation, and protection
of new plantations or regeneration
areas are three common situations
in which use of chemicals might be
essential to timber, recreation, or
watershed values.
In principle, any such materials
might enter streams either by direct
application from aircraft or sprayers,
or after washing over or through
the soil, or through gross spills and
carelessness. The first of these is
sometimes thought to be the major
concern, although the latter is likely
to be the most difficult to predict
and control.
For the most part, the compounds
applied to forests will be similar to
those used elsewhere in properties
such as persistence, toxicity, mode
of decomposition, and fixation or
accumulation by soil, and will be
subject to similar precautions. In
some instances, however, there may
be special problems of forest use aris-
ing from difficulties of precise appli-
cation on rough terrain, or to coarse
or rocky soils, or to the possibility
of rapid, short-distance transport into
streams — as, for example, after
treatment of riparian areas. Further-
more, the quality standards applied
to headwater streams may well be
more stringent than tolerated else-
where.
But in all this it should not be
forgotten that by far the largest frac-
206
I (RESTS
tion of forested land is entirely un-
treated with pesticides of any sort,
and the greatest part of the remainder
would be treated only at intervals
of several to many years. For ex-
ample, a single application of 2,4,5-T
to control overtopping brush on re-
generation areas probably would not
be repeated within the life of the
new stand.
Numerous monitoring studies with
insecticides such as DDT and its suc-
cessor materials during the past two
decades have demonstrated the mag-
nitude of direct and secondary input
into streams to be expected from
broadcast aerial applications. These
also indicate both the hazards of
applying highly toxic or persistent
materials in this way and the meas-
ures required to avoid or minimize
direct contamination of waters. Again,
fewer though significant studies with
ground and aerial applications of
herbicides demonstrate that careful
regulation of mode, rate, and season
of application allows use even in
streamside areas with no or minimal
contamination. Since phenoxy and
amitrole herbicides degrade fairly
rapidly in the forest floor, confining
application to places and seasons
where overland flow will not occur
within a month or two avoids possible
runoff.
But, plainly, continued systematic
experiments with pesticides or other
easily detected markers under a large
variety of field conditions is needed
to insure a high degree of predictabil-
ity. Moreover, the increasing con-
straint on the use of some materials
is likely to place a high emphasis on
development of nontoxic or easily
decomposed materials, and on alter-
native strategies of pest control.
The Effects of Fire — Concentra-
tions of dissolved solids in forest
streams are normally low, and in-
creases of any magnitude are usually
associated with major disturbances
or additions. From time to time
concern has been expressed over the
effects of fire, clearcutting or other
destruction of cover, increased area
of nitrogen-fixing vegetation, and
forest fertilization. Unfortunately, at-
tention is sometimes directed solely
to maximum concentrations in the
waters from the affected areas. When
the aggregate of small watersheds
forming a single forested drainage
basin is viewed as a system over
time, however, events affecting small
areas and at long intervals, such as
clearcutting in a sustained-yield for-
est, necessarily have only minor in-
fluences on the quality of large-
volume streams issuing from the
entire basin. In contrast, drastic
large-area events such as a major
wildfire or insect pandemic could
increase outflow concentrations for a
relatively brief period.
Plant ash remaining after severe
fires can temporarily raise the base
content and alkalinity of streams
from affected areas. Accelerated de-
composition of organic matter in and
on the mineral surface after fire may
increase nutrient outflow, though this
has not been demonstrated. These
several changes are probably trivial,
however, in comparison with more
serious and long-lasting effects on
water temperature, turbidity, and
flow characteristics, especially if re-
establishment of cover is long de-
layed.
But fires are of many kinds, and
forest landscapes vary enormously in
susceptibility to post-fire erosion.
Turbid streams, floods, and disastrous
mudflows are well-known conse-
quences of fire in the steep brush-
lands of southern California. (See
Figure VII-5) There are many such
landscapes with highly combustible
vegetation where uncontrolled fire is
a major hazard to watershed values,
including water quality. Well-docu-
mented case histories, as well as
small-scale experiments, thoroughly
demonstrate the flood peaks, gulley-
ing, sediment transport, and channel
tilling, as well as long-term impair-
ment of water quality following
severe wildfires on sensitive soils and
slopes. Hence, research on fire be-
havior and control, fuel reduction
prescribed fire, and wildfire detec-
tion and suppression are essential to
maintenance of water quality. This
point is too often overlooked, and
efforts at economic analyses or "total
social costs" fail to weigh the proba-
bility— and overwhelming damage —
of major wildfires against the costs
and minor damages of roads or other
measures that facilitate fire control.
Disastrous effects on water quality
from wildfire are far from universal,
however. In some places, wildfire
may be followed by significant sur-
face washing or mass movement but
part or all of the sediment comes to
rest and is stabilized before reaching
the streams. Furthermore, there are
large areas of stable soils and slopes
that resist detachment and maintain
adequate hydrologic capabilities even
after severe fires.
Much remains to be learned about
soil and water behavior following
fire, and especially about mass move-
ment on steep or unstable slopes,
about the possibilities of adverse
precipitation events in the interval
before revegetation of newly burned
surfaces, and about seeding or other
measures to hasten such revegetation.
The sheer magnitude and obviousness
of the immediate post-fire conse-
quences, the costs and complexities
of long-term studies on large burns,
and concern with newer threats to
water quality tend to divert attention
from quantitative studies of recovery
processes.
Nevertheless, present knowledge
allows arraying likelihood and pos-
sible extent of wildfire influences on
a scale from none to very great,
according to landscapes, fuel type,
and fire characteristics. Such knowl-
edge also allows use of prescribed
fire, at times of low hazard, for a
variety of purposes — preparation for
regeneration, improvement of wild-
life habitat, and, notably, reduction
of accumulated fire fuels that would
otherwise vastly increase wildfire
hazards. In most of the southern
207
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
Figure VII-5 — EFFECTS OF FOREST FIRES
The upper photograph shows an orchard near Santa Barbara, California. The single
open storm drain was normally adequate to handle storm runoff. In 1941, however,
the region enclosed by the dotted line was burned out in a brush fire. The lower
photograph shows the debris deposited by the runoff of a single light rain after
the fire.
pine forests prescribed fire is actually
a legacy from annual burning by
Indian populations, and several stud-
ies fail to show any deleterious con-
sequences of its repeated use. Known
or probable exceptions, however, are
some areas of new forests planted
on severely eroded lands, and some
steep and sensitive soils. Again, some
studies of "slash burning" for reduc-
tion of logging debris in the Douglas
fir region reveal that the soil cover is
totally removed from only a small
percentage of the burned area so
that infiltration remains high and
sedimentation negligible. But greater
fire severity, or slopes on which mass
movement occurs, increases the likeli-
hood of soil movement into stream
channels. Generally feasible alterna-
tives to fire have not yet been
found, but several interests — includ-
ing smoke abatement, possible value
of logging wastes, and fish manage-
ment, as well as water quality per
se — have encouraged such research.
In some regions the predominance
of alder and some other nitrogen-
fixing shrub species can be increased
by fires, disturbance, or silvicultural
treatment. Stands of alders fix sig-
nificant quantities of atmospheric
nitrogen, and some fraction of this
addition enters streams. The extent
of such contributions and their even-
tual effect on stream concentrations
are unknown, except by order-of-
magnitude estimates. However, these
indicate that fixation per unit area
over a period of some years must
often exceed the nitrogen additions
considered in forest fertilization pro-
posals. Hence, consequences of these
natural additions are of very con-
siderable interest.
Reduction of the forest cover by
fire, wind, insects, and clearcutting
causes an abrupt increase in surface
temperatures and in mineralization
of the organic matter. The resulting
nutrient release may be followed by
increased leaching of nitrates and as-
sociated cations into streams. These
effects are highly dependent on cli-
mate and the quantity of surface
organic matter, and on the rapidity
with which a new cover of vegetation
appears. The well-known studies at
Hubbard Brook (New Hampshire),
although artificial in some degree,
served to focus attention on the
maximum quantities of nutrients that
may thus enter streams. Several other
studies in regions of lesser organic
accumulation and where natural re-
vegetation is allowed, show only
minor increases. A considerable
number of experimental treatments
and monitoring to study this effect
further are now under way.
Virtually no attention has been
given to other forest management
treatments which probably act in
the same direction although at lower
intensity. These are drainage of for-
ested wetlands, broadcast burning,
and site preparation by destroying
vegetation and disturbing the soil.
208
FORF.STS
The exact magnitude will be highly
variable, depending on soil and cli-
mate. The effects of all such treat-
ments on nutrient release, like those
of clearcutting, are temporary, self-
limiting, and not subject to recur-
rence on the same area within the
foreseeable future. Though these
nutrient changes may be conse-
quential for vegetation on the treated
area, estimates suggest that any in-
fluence on water quality must be
slight.
The Effects of Fertilizers and Other
Nutrient Sources — In recent years
there has been a sharp increase in
the number of experiments and op-
erational trials using artificial fer-
tilizers to increase timber growth and
wildlife food supplies, and to develop
protective vegetation on disturbed or
eroded soils. Large-scale applications
of nitrogen on timberlands, notably
in the Pacific Northwest, have pro-
voked concern that the added fer-
tilizer would enter streams and lakes,
increasing eutrophication and perhaps
reducing quality of urban water sup-
plies.
Several lines of evidence, including
lysimeter studies on fertilized areas
as well as the "clean-up" of sewage
and other waste waters applied to
forest soils, demonstrate that forest
ecosystems are highly efficient col-
lectors and "sinks" for added nutri-
ents. The capacity of such sinks ap-
pears great due to the large biomass
low in nutrient content, wide carbon-
nitrogen ratios of forest organic mat-
ter, and the high phosphorus-fixing
capabilities of most mineral soils; but
the details are poorly known. Again,
the possibility of increased nutrient
content in soil and vegetation result-
ing from fertilization has raised the
possibility of greater release follow-
ing timber harvest. Such questions
point to the need for far more precise
characterizations of the "compart-
ments" and "fluxes" of ecosystem
models before these can have any
predictive value.
Present knowledge of the fate of
nutrients entering the soil indicates
that the more serious source of water
contamination would be direct entry
of the applied fertilizers into streams
and lakes. This might occur either
through the distribution into such
waters during aerial application, or
in consequence of surface washing
at some periods of the year. The
latter chiefly concerns the borders of
streams and the associated system
of "temporary" streams where over-
land flow mass occurs briefly at pe-
riods when the underlying soil is
saturated. The extent of such channel
expansion and its role in transport
of dissolved or fine suspended mat-
ter has been generally overlooked.
Thus far, however, the forest land
managers involved have been highly
sensitive to water-quality considera-
tions and have withheld application
of nitrogen fertilizers in the vicinity
of lakes or streams. In consequence,
the tolerable upper limits of rate and
distribution are as yet unknown. But
several studies of fertilized water-
sheds and monitoring of streams
from fertilized areas are already un-
der way and will warrant continued
attention.
Another important localized source
of nutrient enrichment comes about
through the high concentrations of
recreational users at major camp-
grounds, ski developments, and the
like. Treatment of the human waste
generated at such areas may or may
not render the effluent waters "micro-
biologically safe," but the nitrogen
and often the phosphorus contents
usually enter the streams. The result-
ing nutrient load is susceptible to
reasonably accurate determination,
but the effects on the biology of
headwater streams and the magnitude
of such enrichment in comparison
with other sources mentioned above
certainly require study. This problem
is only marginally a concern of "for-
est management," but in the face
of steadily increasing recreational de-
mands the solutions are likely to be
difficult or expensive. Among the
options will be prohibition of such
use, elaborate treatment plants or
new technologies of waste
or acceptance of altered water qu
In any case, both the projection of
recreational expansion and hydrolog-
tcal data on the streams should be
adequate for prediction of conse-
quences when such recreational uses
are being considered.
Bacteriological Quality — Increas-
ing recreational use is also a major
threat to bacteriological quality of
water from forested areas. Small
numbers of hikers and workers, like
small stock and wildlife populations,
can use a large area without making
much impact. But in forest areas
heavily used by campers, hikers, or
workers human waste treatment is
commonly inadequate, primitive, or
nonexistent, posing possible hazards
to downstream users of untreated
waters from such areas. Routine
treatment offsets any such threats in
urban distribution systems but the
problem of reconciling health, aes-
thetics, and recreational use remains.
Sediment, the Pre-eminent Fac-
tor — Concern with the varied as-
pects of water quality, though nec-
essary, sometimes deflects attention
from sediment load, which is the
major, most costly, and almost ubiq-
uitous cause of impaired quality. Fine
suspended matter, mineral or organic,
as "silt" or "turbidity," imposes high
treatment costs for urban and some
industrial uses. It also clogs irri-
gation ditches, destroys spawning
grounds and bottom vegetation, and
reduces recreational and scenic val-
ues. Coarse materials fill channels
and divert streams in flood, and
often destroy the usefulness of
flooded lands.
Sediment movement into streams,
together with flow rate and land-
treatment effects, have been the main
thrust of watershed research. As a
result, the sources of fine and coarse
sediments in forest watersheds are
reasonably well known, as are the
general relationships between sedi-
ment production on the one hand, and
209
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
Figure VII— 6 — RELATION OF SEDIMENT PARTICLE-
SIZE TO FLOW RATE
hon
"i r
10
i r
PERCENT
J I L_
10 20
SAND
30
40
50 60
SILT
70
20
30
CLAY
40
The graph shows lines of best fit for measurements of sediment particle-size dis-
tribution made from 1961 to 1964 in the Scott Run basin, Fairfax County, Virginia.
There appears to be no change in particle-size distribution with time. The low-flow
regimes show high concentrations of silt and clay. As the flow decreases and the
speed slows, the silt particles — being heavier — drop to the stream bed, leaving the
fine clay particles to become the greater portion of the load. As the flow increases,
there is an increasing concentration of the larger, sandy particles.
hydrological behavior and disturb-
ance of vegetation on the other. (See
Figure VII-6)
On the majority of forest water-
sheds, the principal cause of erosion
and stream turbidity outside of flood
periods is exposure or disturbance
of the mineral soil surface. This may
come about through any of a number
of causes — excessive grazing, tram-
pling by livestock or humans in large
numbers, roads and skid-trail con-
struction, and, as mentioned, some-
times after severe fire.
Current overgrazing and the legacy
from even more severe overgrazing
in the past poses severe problems in
some low-rainfall forest areas of
western United States. Reducing fur-
ther damage by livestock, and occa-
sionally by big game, is more of a
political-economic problem than one
of technical know-how. Repair of
past damage, however, is handi-
capped by the large area and low
values of affected lands, the slow
pace of natural recovery, and limited
funds for both research and applica-
tion of known principles.
Increasing recreational uses — in-
cluding human traffic on trails and
campgrounds, development of roads,
ski runs, facilities, and now the
large numbers of off-the-road ve-
hicles — create an array of new prob-
lems for forest land management.
Obviously, hazard to water quality
is only one of these, though often
significant. Less obviously, new kinds
of use conflicts are being generated,
and research in behavior and values
is likely to be as important in ad-
dressing these as is that in economics
and watershed management.
Contrary to popular belief, the
mere cutting of trees, even com-
pletely and over large areas, seldom
leads to any surface erosion, espe-
cially if regrowth occurs promptly.
The critical factor determining
whether logging operations will or
will not influence stream turbidity
is how the felling, skidding, and
hauling are conducted. There is now
a substantial body of research and
experience in several forest regions
demonstrating that the mechanical
operations and necessary road con-
struction can be carried on with
minor or no impact on watershed
values and stream turbidity.
Several essential principles of road
design, construction, and mainte-
nance, as well as for protection of
stream channels, have emerged that
minimize soil exposure and arrest
sediment transport. These principles
are readily translated into practice
in many landscapes, though the op-
erational details and controls are
known for only a few. In some steep
mountains or slide-prone areas, how-
ever, geological structure and topog-
raphy impose unforeseen hazards and
extremely high costs. Greater avail-
ability of soil and geotechnical in-
formation might reduce both, though
the resources for providing informa-
tion to large wildland areas are
meager. In any case, cost factors as
well as watershed considerations have
dictated new attention to harvesting
and transport systems, including the
long-used aerial cable methods and
feasibility tests with balloon and heli-
copter logging.
210
FORESTS
Hence, with the exception of
fragile or very steep lands, our pres-
ent levels of knowledge and tech-
nology are generally adequate to
minimize these sources of disturbance
or reduce their consequences. This is
true even though many elements —
including lack of exact prescriptions,
increased costs, momentum of exist-
ing systems, and unawareness of
long-run damages — may cause ac-
tual practice to lag well behind the
prospects demonstrated by research.
Needed Scientific Activity
As the foregoing indicates, a sub-
stantial body of knowledge and
application has been accumulated
through "watershed" or "watershed
management" research on forest
areas. Extension of research results
and at least qualitative predictions
to similar landscapes can be made
with some confidence. Greater cer-
tainty, exactness, and extent of pre-
dictions are possible simply through
increased funding of existing re-
search installations. Predictive mod-
els and simulation relating streamflow
to physical variables and precipitation
are being explored by hydrologists.
Success would bring extension to
forest watersheds for which numer-
ous data are available, and might
call for new modes of examining
factors controlling surface soil loss,
bank erosion, or other sources of
turbidity.
Nevertheless, even within current
concepts, there are enormous gaps
in our knowledge of watersheds.
Many large areas are poorly known
in terms of exact climatic data, soil
units, and the hydrologic behavior
or response of watersheds to treat-
ment. In some instances, the simple
conceptual models derived from study
of soil in the laboratory or agricul-
tural field bear little resemblance to
the behavior of wildland soils, es-
pecially those on very steep slopes.
Much greater efforts at watershed
characterization and in study of the
actual functioning of small soil-
geomorphic "systems" under field
conditions are badly needed. Such
work is not entirely lacking (see
Figure VII— 7), but the investigators
so employed are few and the number
of mixed-discipline investigative
teams far fewer, especially in the
light of the large areas involved.
Three examples illustrate such
needs :
1. Only within the last decade
has it been recognized that fire
on the steep California brush-
lands not only destroys the
protective cover of vegetation
and litter but also imparts a
non-wettable quality to the soil
itself, apparently through con-
densation of heat-volatilized
substances from the litter. The
result is reduced entry of rain-
fall, increased surface flow, and
erosion. This complexity has
required new research
proaches, and calls for revision
of existing notions of infiltra-
tion in both burned and pro-
tected soils.
2. Hewlett's variable source area
concept of water outflow, al-
luded to earlier, is still novel
and its consequences for water
quality are only now being ex-
plored. In certain landscapes
it seems to provide a mechan-
ism for direct overland trans-
port of surface materials to
streams without passing
through the soil filter, a pos-
sibility usually overlooked.
3. Again, assessments of land-
scape stability, normal sedi-
ment loads, and tolerance of
man-made disturbance are com-
monly based on short time
periods and assumptions of
Figure VII-7 — EFFECT OF LAND USE ON SEDIMENT
YIELD AND CHANNEL STABILITY
Land use
A. Natural forest or grassland.
B. Heavily grazed areas.
C. Cropping
D. Retirement of land from
cropping.
E. Urban construction.
F. Stabilization
G. Stable urban
Sediment yield Channel stability
Low Relatively stable with
some bank erosion.
Low to moderate Somewhat less stable
than A.
Moderate to heavy _ Some aggradation and
increased bank
erosion.
Low to moderate Increasing stability.
Very heavy Rapid aggradation and
some bank erosion.
Moderate Degradation and
severe bank erosion.
Low to moderate Relatively stable.
The table shows various land uses and their effect on the relative sediment yield
from the surrounding landscape as well as on the stability of stream channels. The
most severe sediment problems occur during urban construction, when covering
vegetation is removed and the flow regime in channels is changed by realignments,
increases or decreases in the flow, or obstructions placed in or alongside the natural
flowway.
211
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
gradualness. But the geologic
processes that shape the steep
lands are often violent and er-
ratic. Landslides, avalanches,
massive floods, and abrupt
changes in stream cutting and
deposit are normal incidents in
the down-wearing of steep
mountain slopes. Since hazard
is often unsuspected and fre-
quency is on a larger scale
than laymen reckon with, such
events often appear as "ac-
cidents" or are attributed to
the wrong causes.
It is clear that man's activities in
some susceptible landscapes decades
and centuries ago have increased the
frequency or severity of such events
and triggered self-accelerating erosion
of unstable slopes. Now, landslides
and slips associated with road con-
struction are a continuing problem
as roads are extended into steep
remote areas. Hence, there is need
for much better understanding of
soil and geomorphic processes on
vulnerable steep lands with a view
to characterizing hazards and devis-
ing measures of avoidance or control.
Such research concerns not only
forest management operations but
equally highway construction, ski-
slope developments, powerline clear-
ance, mining, and all other activities
that change stream courses, slope
loading, or the stabilizing effects of
vegetation.
Factors Relating Forest Management to Water Quality
Water derived from forested wa-
tersheds is generally the highest-
quality water found under natural
conditions although, contrary to pop-
ular opinion, water from pristine
forest streams is frequently unsafe
for human consumption. Under nat-
ural conditions, water quality is a
function of:
Geology and Geochemistry — Par-
ent materials and the products of
their weathering influence mineral
content.
Topography — Elevation, exposure,
and steepness influence the form of
precipitation, time and mode of de-
livery, evaporation rates, water tem-
perature, infiltration opportunity.
Climate — Climate influences or
determines the amount and form of
precipitation input and the time and
mode of delivery of water; indirectly,
it influences sediment and organic
content, rate of weathering, soil de-
velopment, and vegetative cover.
Soils — Type and depth of soil
mantle are significant factors in wa-
ter quality determination, especially
in surface water. They influence the
rate and amount of infiltration and
percolation and, consequently, quality
and amount of groundwater recharge,
the rate and amount of erosion, and,
thus, the sediment and chemical con-
tent of surface water. Soil influences
biological activity and nutrient cy-
cling processes and is a determining
factor in type and density of vegeta-
tive cover.
Biota — Includes animal and plant
forms. Animals, from soil bacteria
and microorganisms to large wild-
life forms, play a significant role in
determining water quality. Similarly,
vegetative forms from lowly mosses
through forests exert an influence on
water quality. These combined in-
fluences include bacteria, nutrients,
organic matter, and sediment or tur-
bidity content, hydrogen ion activity,
suspended solids, and water tempera-
ture.
Natural Disturbances — Natural ca-
tastrophes including forest fires, in-
sect and disease depradation, earth-
quakes, volcanic eruptions, landslides,
avalanches, hurricanes, and tornadoes
all influence water quality, often in a
major way.
The Role of Forests
Forest vegetation influences and in
turn is influenced by climate, soil de-
velopment, geologic weathering, other
biota, and natural disturbances. Ex-
amples of some forest influences
which directly or indirectly affect
water quality include:
1. An ameliorating influence on
local climate leading to lower
water temperatures and lower
evaporation rates and also, usu-
ally, to greater transpiration
rates and higher production of
atmospheric oxygen.
2. A favorable influence in reduc-
ing flooding levels, erosion,
and consequent sedimentation
production and turbidity in
streams.
3. A favorable influence in the
area of nutrient cycling; more
nutrients are held in and on
forest land.
4. High production of organic
matter may produce short-term
discoloration, and sometimes
odors, in surface water. At the
same time, this organic material
has a very favorable influence
on biotic activity in and on soil.
5. Forest vegetation, particularly
deep-rooted types, tend to pro-
vide optimum natural protec-
tion against avalanching and
landslides.
6. Forests generally consume more
water than other vegetation;
thus, less total water may be
available downstream for dilu-
tion.
7. Forests tend to buffer highs and
lows of streamflow volume and
the quality of this water.
212
FORESTS
Impacts of Forest Management
on Water Quality
Other than changes brought about
by the (usually rare, except for forest
fires) catastrophic natural disturb-
ances over which we have little or no
control, the major changes wrought
in water quality from forested water-
sheds are those resulting from man's
activities. Major disturbances and
and activities due to forest manage-
ment and man's activities include:
fire, forest clearing or removal, timber
harvest, road and right-of-way con-
struction, cultural operations, insect
and disease control, solid waste dis-
posal, and recreational activities and
developments.
Forest Fires — Whether natural,
deliberate, accidental, or incendiary,
forest fires are generally conceded to
have a deleterious effect on water
quality. The degree of influence de-
pends on the type and intensity of
the fire, the time of year, and topo-
graphic and soil conditions. Ground
fires occurring on stable soils may
produce only minimal deterioration
in water quality, while intense fires
on sensitive soils and on steep slopes
may occasion serious damage. Effects
on water quality may be due to in-
creased water temperatures, increased
ash, mineral, and organic content, as
well as higher sediment and turbidity
loads due to increased runoff and ero-
sion. The effects may be restricted to
a single season or year or they may
last up to several decades.
Fire used as a management tool —
e.g., to effect deliberate ecological
change, to control insects and disease,
or for slash disposal — is ordinarily
planned in areas and at seasons when
damage to water quality would be
minimal.
Forest Clearing — Removal of for-
est for agricultural land use, for urban
or industrial development, or for vege-
tative-type conversion (e.g., forest to
grass) may completely alter the
water-quality regime. Changes will be
greatest during the period of maxi-
mum disturbance. Following recov-
ery, the water-quality regime will take
on the characteristics of the new
land-use pattern. In some cases —
e.g., the conversion of pinyon juniper
or chapparal forest types to grass —
there may be an improvement in
water quality from the sediment-
turbidity standpoint.
Timber Harvest — The effects of
timber harvesting on water quality
will depend on the intensity and type
of harvest operation and on the man-
ner of product removal. Light selec-
tion cuts will normally have minimal
or no effect, while clear cuts that open
up large areas will tend to increase
water temperatures and increase the
potential for subsequent erosion and
sedimentation. Contrary to popular
belief, the removal of the forest crop
itself ordinarily does not occasion
serious damage except on very steep
slopes or on unusually sensitive soils.
The major damage is usually due to
harvesting and removal methods —
i.e., skid trails, log landings, heavy-
equipment disturbance, and, espe-
cially, road construction and inade-
quate maintenance. On occasion,
yarding areas or equipment servicing
areas may provide a source of con-
tamination as a result of oil, gasoline,
or chemical spills.
Road Construction — Road and
right-of-way construction in forests is
a major problem insofar as water
quality is concerned. During and fol-
lowing clearing and construction,
substantial areas of raw roadbed and
cut-and-fill slopes are exposed to ero-
sion; frequently, large amounts of
erosional materials are washed into
stream channels. Damage can be sub-
stantially reduced through road loca-
tion, carefully supervised construc-
tion methods, immediate rehabili-
tation of exposed areas, and good
maintenance practices. The same
holds true for the construction of
rights-of-way for power lines, pipe-
lines, and waterways (surface or un-
derground).
Cultural Operations — In addition
to the harvesting process, intensive
forest management may i;
or more cultural operations such as
forest thinnings and cleanings. When
such operations are done mechani-
cally, little or no impairment of water
quality should result. However, when
chemicals such as sodium arsenate
or 2,4,5-T are applied, caution must
be exercised to keep such materials
away from streams.
Insect and Disease Control — To
protect commercial and noncommer-
cial forests, wilderness, and recrea-
tion areas as well as forest parks from
periodic disease and insect epidemics,
control operations are essential. The
most effective and most economic
control methods have involved chemi-
cals such as DDT. The environmental
dangers inherent in chemical control
methods, including water-quality de-
terioration, have become increasingly
apparent and controls have recently
been imposed. In some cases, con-
trolled light ground fires in forest
areas have been applied to destroy
vectors. Such operations have little
influence on water quality if applied
carefully under controlled conditions.
Ecologic controls also have little or
no impact upon water quality.
Solid Waste Disposal — In har-
vesting timber crops as well as in
the primary conversion (sawmilling),
relatively large volumes of solid
waste in the form of slash, slabs, and
sawdust need disposal. To accelerate
new forest development, to destroy
breeding areas and food for forest
insects and disease pests, and to en-
hance the forest environment it has
been a common practice to burn the
forest slash. While such practices
have only minimal effect on water
quality, they are being halted in many
forest areas due to air-pollution con-
siderations. Similarly, at primary
conversion plants there are major
problems in the disposal of sawdust,
slabs, and edgings. Again, fire has
been used as a primary method of
disposal but is now being drastically
reduced due to air pollution. Some
of this waste material is being used
213
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
to produce secondary products such
as compressed-sawdust fireplace logs.
Recreation Activity and Develop-
ment — Outdoor recreation activity
and developments in forest areas are
increasing many-fold each year and
are contributing to water-quality
problems. Some of the forest wilder-
ness areas are now badly overused,
and lack of sanitation facilities and
overuse by horse pack trains as well
as human trampling are locally lower-
ing water quality. A major problem
in many forest areas results from in-
creasing use by four-wheel-drive ve-
hicles and trail motorcycles which
increase erosion and add to sediment
problems in streams. Recreation de-
velopments in the forest ranging from
camp and picnic grounds and summer
homes to large ski areas are fre-
quently poorly designed or poorly
maintained from the standpoint of
sanitation; they, too, are contributing
to water-quality degradation.
Other Forest Uses — Special uses
of forest land — such as grazing by
domestic livestock, mining opera-
tions, and summer colonies or com-
munes of people living on forest
areas — may contribute special prob-
lems in water quality. In general,
grazing by domestic livestock is de-
creasing on forest lands; conse-
quently, from this standpoint an
improvement in water quality can be
expected. In mining operations in-
volving large-scale land, subsurface
disturbance, and road construction,
water-quality problems increase,
sometimes markedly, both from the
standpoint of erosion and attendant
sediment production and in mineral
content of both surface and ground
water.
Steps Needed to Improve
Water Quality
While the quality of water derived
from forest lands is in general supe-
rior to that from other types of land-
scapes or land uses, there is degrada-
tion in many areas. Action is needed
to protect water quality where it is
good and to improve that which is
being downgraded.
Water-Quality Standards — By fed-
eral legislation each state has had to
set water-quality standards. Unfor-
tunately, in many areas the standards
set for some streams are higher than
natural, or "pristine," water. For vari-
ous reasons, many states lack back-
ground data on natural water quality.
If realistic standards are to be set and
observed, some additional monitoring
of forested water-source areas is
needed.
Application of Available Knowl-
edge — In many instances, degrada-
tion of water quality is due to lack
of application of principles already
known to us. More rigid require-
ments can be written into timber sale
and road construction and mainte-
nance contracts and then enforced.
Where sanitation facilities are inade-
quate around recreation sites or sum-
mer homes, forced improvement or
closure can improve water quality.
Closure or zoning of forest areas to
specialized uses such as four-wheel-
drive vehicles can be helpful. Re-
duced use of sensitive wilderness
areas or elimination of horse traffic
in such areas is likewise an available
tool.
Neio Research — In many in-
stances, remedial measures will be
conditioned by the availability of new
research information. Examples in-
clude: What is the human carrying
capacity in parks and forest recrea-
tion areas with respect to water
quality? What type of chemicals, and
in what concentrations, can be used to
control insects, diseases, and weed
species without impairment of water
quality? What type and pattern of
forest harvesting can be safely ap-
plied? At what seasons of the year
should we restrict forest use to pro-
tect water quality? What type of
mineral extraction activity is permis-
sible and what kinds of safeguards
are necessary? How can forest areas
be used safely and beneficially in
solid waste disposal — wastes from
the forest itself (slash) and from in-
dustries and municipalities? What is
the impact of watershed management
activity to increase water yields on
the water-quality regime? What are
the relationships between wildlife
use and domestic grazing and water
quality?
214
3. AGRICULTURE
Global Food Production Potentials
By the development and applica-
tion of technology in food production
the world can be well fed generally,
even with its prospective doubling
of population by the year 2000. The
physical, chemical, biological, and en-
gineering sciences must be used to
develop production systems that will
effectively utilize arable land, water,
solar energy, energy from fossil fuel
or other source required for mechani-
zation of agriculture, improved seeds,
livestock, fertilizers, pesticide chemi-
cals and other pest-protection means,
genetics, ecology, disease and para-
site control in man and animals, social
science relevant to industrialization
of agriculture and urbanization of the
world generally, and the building and
use of scientific and technological
capability in every country to meet
its needs.
A great deal of science basic to
agriculture has happened because
men wanted to find out why — why
tillage was useful — why fallow was
useful — why ashes stimulated new
plant growth. Man learned by expe-
rience; he knew even in ancient times
that good seed, in good soil, well
watered under a friendly sun pro-
duced a good harvest. The major
plant nutrients required have been
known for more than a hundred
years. Commercial manufacture of
superphosphates began about 1850,
although nitrogen did not become
available in Germany until World
War I and in the United States until
1925. Mined potash and sulfur sup-
plement natural reserves.
Current Scientific Understanding
The theoretical scientific basis of
plant nutrition is an essential and
major portion of the science basic to
agriculture and world food produc-
tion. Soils of the world vary widely
in their reserves of major and minor
plant nutrients. Some of them con-
tain toxic amounts of such minerals
as molybdenum or selenium. Others
are very deficient. Amendment de-
pends not alone on mineral analysis
but also on the physical nature of
the soil and its ion exchange capacity.
The ability of the soil to produce
crops must be assessed locally, often
repetitively.
It has been estimated that there are
potentially arable lands in the world
equal in area to those now under
cultivation — i.e., around 1.5 billion
hectares. (See Figure VII-8) One
of the recommendations of the Presi-
dent's Science Advisory Committee
on The World Food Problem was:
"The agricultural potential of vast
areas of uncultivated lands, particu-
larly in the tropical areas of Latin
America and Africa, should be thor-
oughly evaluated."
Water is a major factor in all food
production. The science of hydrol-
ogy, the technology of water manage-
ment are basic to agriculture. Irriga-
tion — with its concomitant problems
of waterlogging or drainage, salinity
Figure VII-8 — POTENTIALLY ARABLE LAND
IN RELATION TO WORLD POPULATION
Continent
Population
in 1965
(millions
of persons)
Area
in billions of
acres
Acres of
culti-
vated
land per
person
Ratio of
culti-
vated to
potentially
arable land
(percent)
Total
Poten-
tially
arable
Culti-
vated
Africa
310
7.46
1.81
0.39
1.3
22
Asia ..
. 1,855
6.76
1.55
1.28
.7
83
Australia and
New Zealand
14
2.03
.38
.04
2.9
2
Europe
445
1.18
.43
.38
.9
88
North America
255
5.21
1.15
.59
2.3
51
South America
197
4.33
1.68
.19
1.0
11
U.S.S.R.
Total
234
5.52
.88
.56
2.4
64
3,310
32.49
7.88
3.43
1.0
44
The table shows the total area of the continents of the world, the part that is po-
tentially arable, and that which is presently being cultivated. The cultivated areas
include land under crops, temporary fallow, temporary meadows, lands for mowing
or pasture, market and kitchen gardens, fruit trees, vines, shrubs, and rubber planta-
tions. The land actually harvested in any given year is about one-half to two-thirds
of the total cultivated land. Of the potentially arable land, about 11 percent of the
total requires irrigation for even one crop. It is important to note that Africa.
Australia and New Zealand, and South America cultivate significantly less than
half of their potentially arable land. The continents where most of the land is being
used are those where the population density is greatest.
215
PART VII — WATER RESOURCES, FORESTRV AND AGRICULTURE
or leaching — poses added problems
for hydrologists and engineers. But
these areas of science and technology
are useless unless they are used in
adequate systems of agronomy, in-
volving knowledge of soil chemistry,
soil physics, plant physiology, plant
genetics, and soil-plant-water rela-
tionships in every microclimate where
crop plants are grown.
Science basic to optimal use of
solar energy and science basic to
effective use of fossil fuel or other
energy source in crop production,
transportation, and storage and proc-
essing of food crops is essential. In
many countries, fossil fuel must be
imported while human labor is in
oversupply. Since a man is equivalent
only to about one-eighth horsepower,
it is difficult, if not impossible, to use
enough human labor at the precise
time when planting, harvesting, or
cultivation is required.
Crop-Plant Genetics and Breeding
— Genetic capacity of crop plants
and livestock species for the produc-
tion of food useful and acceptable to
man is a first requirement. Comes
then the question of whether native
plants and animals developed in and
adapted to the many niches of a local
ecosystem are better suited to serve
man's needs there than those intro-
duced from other places?
The answer is that, for subsistence
agriculture, the native varieties have
many advantages. Natural selection
over many generations has enabled
them to survive the pests and com-
peting organisms of their area of
origin. But often this adaptation en-
ables them to survive with only a
meager excess for man's use.
When man brings a new seed from
a far place, it often fails in the new
location; but not always. If it hap-
pens to be adapted to the new loca-
tion it may thrive there in the ab-
sences of the diseases and pests it
has left behind. Thus, sunflowers
thrive in Hungary and the Ukraine
while they are little exploited in their
native Kansas, where they are weeds
beset with many enemies. So, too,
soybeans thrive in Illinois — far from
their native China. Figure VII-9
shows two other transplanted species.
Selection, sometimes rather simple
phenotypic selection, has developed
crop plant variants used in various
parts of the world that are often pre-
ferred for organoleptic quality though
inferior in productivity. "Baking
quality" in bread wheat is not useful
in macaroni wheats, for example.
Phenotypic selection continues to be
an important crop-breeding tool.
Science basic to plant breeding has
contributed (a) controlled methods of
hybridization that have added yield
to some crop plants, especially maize;
(b) dwarfism, which has made possi-
ble dramatic yield increases through
response to heavy fertilizer and water
applications without lodging, espe-
cially in rice, wheat, and sorghum;
(c) genetic disease resistance, espe-
cially resistance in wheat to rust; and
(d) selective breeding for photoperiod
Figure VII-9 — TRANSPLANTED SPECIES
HEVEA RUBBER (HEVEA BRASILIENSIS)
I Area of Origin
JHH| Area of Transplanted Species
COFFEE (COFFEA ARABICA)
| Area of Origin
II Area of Transplanted Species
"0
S
J?
The map shows the area of origin of coffee (Coffea arabica) and hevea rubber
(Hevea brasiliensis) and the areas where, having been transplanted, they are now
principally cultivated. In its place of origin, coffee is subject to native red rust
(Hemilaea vastatrix), whereas in the New World, no native diseases exist. Hevea
rubber is found in the New World only in the wild. In the Old World, where major
production takes place today, there are no native pests.
216
AGRICULTURE
response suited to latitude, especially
important in such crops as soybeans,
maize, and wheat.
Each country must have capability
for continued breeding improvement
of the crop plants it produces. Plant
pathogens, for example, often de-
velop new strains virulent to plants
genetically resistant to old pathogens
within a new crop plant generation.
Animal Science — Aside from the
relatively few true vegetarians in the
world, who abstain from milk and
eggs as well as from flesh, animal
protein foods are status foods. Elas-
ticity of demand for animal protein
foods in the developing countries, in
terms of consumer income, is very
high. As income permits, these peo-
ple will demand and obtain larger
amounts of animal protein foods.
While this demand may divert
some cereals from human to animal
food, most animal protein foods in
the developing countries are and will
continue to be produced from forage
and milling offals and other products,
including garbage, rejected as human
food. There is, therefore, a very real
need for the development of research
and technological capability based on
the animal sciences in all countries of
the world.
Among the principal problems re-
quiring attention is research and tech-
nology for the control and eradication
of animal diseases, parasites, and the
arthropod and other vectors of some
of the major diseases of animals and
man. An abbreviated list of the prin-
cipal diseases would include foot-and-
mouth disease, rinderpest, bovine
pleuro-pneumonia, East Coast fever,
African horse sickness, encephali-
tides, African swine fever, malaria,
trypanosomiasis, and schistosomiasis.
Schistosomiasis is a major restraint
on the full realization of the benefits
of irrigation in tropical countries. The
snail intermediate host of this para-
site thrives in irrigation ditches. Two
hundred million people are afflicted.
Research is developing, or has de-
veloped, control methods for all the
diseases listed. Immunization, isola-
tion, and vector control are all im-
portant for one or more of them.
Large game herbivores seem to be
genetically resistant to, or tolerant of,
some of these diseases. Research on
propagation and management of such
species may give new sources of ani-
mal food.
Fisheries as Food Sources — There
is a very wide area of fisheries biol-
ogy, culture, and engineering essen-
tial to the scientific basis for world
food production. Quantitatively, fish-
eries constitute and have potential
for only a minor portion of the
world's food needs. However, in
many nations they represent a quali-
tatively excellent and preferred source
of protein and concomitant minor
nutrients essential to human health
and well-being. Methods of harvest,
preservation, and processing of ma-
rine and estuarine fish and shellfish
and methods of culture and propaga-
tion of estuarine, coastal, and anad-
romous species can protect and in-
crease these sources of high-quality
human food.
In many countries, including our
own, pond culture of carp, trout, cat-
fish, crayfish, frogs, and other edible
fresh-water species have a substan-
tial potential for increasing supplies
of preferred, high-quality protein
foods.
Beneficial eutrophication — utiliz-
ing animal wastes as nutrients in
controlled aquatic ecosystems — of-
fers substantial potential for increas-
ing food production, recycling wastes,
and enhancing the quality of the en-
vironment. Knowledge of fish and
shellfish nutritive requirements, their
reproductive requirements, their dis-
eases and parasites, toxins and con-
taminants, both chemical and biologi-
cal are areas needing research and
technological, institutional, and per-
sonnel capability in many countries.
Arctic and antarctic food produ
tion might be increased by national
and international management of the
harvest of food species and regula-
tion of numbers of competing non-
food species.
Food Protection — Achievement of
the important objective that our food
supply shall be safe and wholesome
requires a basis in many sciences and
a highly varied set of technological
capabilities that must be available in
every country.
Among the principal problems are:
material toxicants (alkaloid and
others); mycotoxins, resulting from
certain strains of mold, potent in
parts per billion, carcinogenic in test
animals; botulinus toxin — food-poi-
soning organisms such as Salmonella;
insect infestations; and spoilage or-
ganisms.
Protection by controlled environ-
ments, chemicals, cold, and steriliza-
tion requires intimate knowledge of
the physical and chemical nature of
food products and the effect of meth-
ods of protection on nutritive and
functional value and on safety and
wholesomeness.
In India, the National Council of
Economic Advisers has estimated that
insects take 15 percent of the stand-
ing crop and another 10 percent after
it is harvested and stored. Losses
from rats are also severe both in
fields and storage bins. Use of plant-
protection chemicals increased from
six million acres in 1955 to a current
200 million acres.
New Directions for Science
The world is principally dependent
for its food supply on a very small
number of crop and livestock species.
Wheat, rice, rye, barley, oats, sor-
ghum, maize and millet, sugarcane,
sugar beets; potatoes, taco, cassava,
sweet potatoes; soybeans, cowpeas,
beans, and peas; vitamins, in variety,
a little protein of fair quality from
217
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
cole crops and other green and yellow
vegetables, from fruits and nuts,
cattle, buffalo, sheep, goats, pigs;
chickens, turkeys, ducks, and geese.
Research is heavily concentrated on
crops of commercial importance. Re-
search on such crops and their com-
mercial production does not help the
subsistence farmer who must trade
his small surplus for the necessities
of life — salt, needles, cloth — that
he is unable to produce. We need
social science to guide us to the as-
similation of the subsistence farmer
into commercial agriculture or to
urban industry. Until recently, ap-
plied research in most developing
countries was poorly financed and
completely lacking in relevance to the
problems of local farmers. Even
where research was directed at pro-
ducing practical results, it was gen-
erally concentrated on cash crops for
export rather than on basic food
staples.
It is not enough to produce high
yields of nutritious grain. In India,
prices for fine-grain rice from old,
low-yielding native varieties are vir-
tually unrestricted while prices of the
coarser high-yielding varieties are
controlled. Total production is re-
duced by diversion of acres from
high-yielding to low-yielding varie-
ties. The affluent pay for what they
want; the poorer consumers become
dependent on rationed supplies of
low-quality grain.
The Institutions — Industrialized
nations of the world have — in in-
stitutions widely varying in structure
— produced, taught, and applied the
scientific information that is the basis
of agricultural technology. In the
United States, federal-state coopera-
tion among the U.S. Department of
Agriculture (USDA) and state agri-
cultural experiment stations in each
of the states provides a useful means
of coordinating research, teaching,
and service. Agricultural research has
had the objective of producing results
useful in improving the productive
capacity of the land, the efficiency of
crop, livestock, and forest production,
the use of agricultural products, and
the welfare of rural people.
This system, while close-knit, is
not closed. Inputs from all the sci-
ence of the world and important con-
tributions to it are commonplace.
Shall at Princeton, East at Harvard,
and Jones at the Connecticut Agri-
cultural Experiment Station at New
Haven all contributed to the scientific
basis on which hybrid corn was de-
veloped. But so, too, did a hundred
others in USDA and the state agri-
cultural experiment stations who
painstakingly identified and modified
the genetic stocks and the ways in
which they could be used effectively
in producing commercial seed for
every latitude in which corn is grown.
Developing nations must have their
own institutions for agricultural
teaching, research, and service. They
emulate the model on which our Land
Grant College system was conceived.
They may find other organizations
better suited to their needs. In any
case, they must have institutions of
their own to produce, teach, and ap-
ply the science and resultant technol-
ogy basic to efficient agriculture in a
coordinated manner.
The Hazard of Drought
In most of the world, where men
till the soil or graze animals, drought
is a recurrent phenomenon. Given
the preponderance of agriculture as a
source of livelihood in the world,
drought emerges as the major natural
hazard of geophysical origin for man
in terms of areal extent and numbers
of population affected, if not in the
intensity of harmful effects. Because
it is a recurrent phenomenon, human
adaptation or adjustment becomes
possible. Indeed, most agricultural
systems involve some adaptation.
This statement takes as its starting
point a human ecological context for
the discussion of drought adaptation,
illustrates the process of adjustment
with two examples from widely dif-
fering societies, and concludes with
suggestions for the development of
certain lines of scientific endeavor
that promise to broaden the range of
drought adjustment available to agri-
culturists.
What is Drought?
In this ecological context, drought
is defined as a shortage of water
harmful to man's agricultural activi-
ties. It occurs as an interaction be-
tween an agricultural system and
natural events which reduce the water
available for plants and animals. The
burden of drought is twofold, com-
prising the actual losses of plant and
animal production and the efforts
expended to anticipate drought, and
to prevent, reduce, or mitigate its
effects.
Several important concepts follow
from this definition of drought. First,
for the purpose of this statement, only
agricultural drought is being exam-
ined; plant-water relationships that
affect, for example, watershed yield
are not considered. Second, drought
is a joint product of man and nature
and is not to be equated with natural
variation in moisture availability.
Natural variation is intrinsic to natu-
ral process and only has meaning for
man in the context of human inter-
action. Third, the measurement of
successful adaptation is in the long-
term reduction of the social burden
of drought, not simply in the increase
in agricultural yield. The scientific
218
i TURE
effort required to improve human
adaptation to drought must meet the
same standards of efficacy, technical
feasibility, favorable cost, and social
acceptance that should govern any
adaptive behavior.
Farmer Adaptation to Drought
In at least three parts of the world,
the problem of human adaptation to
drought is under continuing, inten-
sive study. Saarinen has studied
farmers' perceptions of the drought
hazard on the semi-arid Great Plains
of the United States; Heathcote has
studied pastoral and agricultural
farming in Australia; and Kates and
Berry have carried out pilot studies
of farmer perception among small-
holders in Tanzania. By way of illus-
tration, the work of Saarinen and
Kates can be compared directly, using
farmer interviews from comparatively
dry areas of the respective countries.
The focus in Figure VII-10 is on
actions, on alternative adjustment
strategies to reduce drought losses.
The two studies were carried out
quite independently; therefore, it is
Figure VII-10 — COMPARATIVE PERCEPTIONS OF
FEASIBLE ADJUSTMENTS TO DROUGHT
TANZANIA FARMERS
If the rains fail, what
can a
man do?
ADJUSTMENTS
No. of
Replies
Percent
of
Total
Do nothing, wait.
17
12.14
Rainmaking, prayer.
15
10.71
Move to seek land,
work, food.
51
36.43
Use stored food, saved
money, sell cattle.
16
11.43
Change crops.
9
6.43
Irrigation.
15
10.71
Change plot location.
4
2.86
Change time of
planting.
0.00
Change cultivation
methods.
1
0.71
Others.
12
8.57
Adjustments per farmer = 1.07
99.99
U.S. FARMERS
If a meeting were held and you were
asked to give suggestions for reducing
drought losses, what would you say?
No. of
ADJUSTMENTS Replies
Percent
of
Total
No suggestions 16
8.25
Rainmaking, prayer. 2
1.03
Quit farming. 1
0.52
Insurance, reserves,
reduce expenditures,
cattle. 16
8.25
Adapted crops. 2
1.03
Irrigation. 46
23.71
Change land character-
istics by dams, ponds,
trees, terraces. 26
13.40
Optimum seeding date. —
0.00
Cultivation: stubble
mulch, summer fallow,
minimum tillage, cover
crops. 78
40.21
Others. 7
3.61
100.01
Adjustments per farmer = 2.02
The table shows the replies received from farmers in Tanzania and the United
States when questioned about what they were willing to do in case of drought.
Some 131 farmers in Tanzania and 96 in the U.S. were queried. In Tanzania,
farmers mentioned an average of only one possible adjustment whereas U.S. farmers
could think of an average of more than two to overcome the drought problem.
of considerable interest th I
from differently phrased questions
are comparable. The available
ceived strategies for mechanized U.S.
grain farmers are not intrinsically
different from those of hoe-cultivator
Tanzanians. The mix of perceived
adjustments differs, however — more
actions in total being proffered by the
U.S. farmers, more of these related
to farm practices, and more of these
requiring high-level technological in-
puts. Tanzanian farmers seem more
inclined to pursue adjustments not
directly related to agricultural prac-
tices, and thus are more prepared to
change their livelihood pattern than
to alter their specific cropping be-
havior. Thus, the major contrast
that emerges is between a flexible
life pattern with an unchanging agri-
cultural practice as opposed to a more
rigid life pattern with an adaptive
agricultural practice. These behav-
ioral patterns are suggestive of either
alternative perceptions of nature it-
self or of opportunity for mobility.
The Tanzanian farmer seems willing
to move with an uncertain nature;
his American counterpart appears
readv to battle it out from a fixed site.
Broadening the Range of Available
Adaptive Behavior
A farmer or rancher faces the re-
current, often perennial choice of
plant or grazing location, of the tim-
ing of plant and cultivation, of the
appropriate crops or stock, and of
methods of cultivation and grazing.
In seeking to broaden the agricul-
turist's range of choice of drought
adjustment, the scientist offers his
usual and somewhat paradoxical
knowledge: We know more about
plant-water relationships than seems
evident from the application of our
knowledge; but we know less about
these relationships than we need to
know in order to apply the knowl-
edge widely.
Data Base — - We could now pro-
vide for many parts of the world
much improved information on which
219
PART VII — WATER RESOURCES, FORESTRY, AND AGRICULTURE
to base these decisions. To do so we
would need to bring together the
scattered record of climate, the frag-
mentary knowledge of soil, the dis-
persed experience with varieties and
breeds, and the complex measure-
ments of the impact of cultivation or
grazing practice on available soil
moisture. Within a framework of
water-balance accounting, simulated
traces of climatic data can provide
probabilities of moisture availability
directly related to specific varietal
needs or stocking patterns. If these
probabilities are used as appropriate
weights in programming models, crop
yields may be balanced against
drought risk, desirable planting times
determined, or the role of labor-
or capital-intensive moisture-conserv-
ing practices assessed.
A special role for the use of such
data is for the planned agricultural
settlement. Wherever men are in-
duced to move to new, often strange
environments, greater drought risks
are often incurred as a function of
their ignorance. The dust bowls of
the American West, the Virgin Lands
of the Soviet Union, and the Ground-
nuts Scheme of colonial Tanganyika
provide tragic evidence of the uni-
versal cost of learning about new
environments even with, or perhaps
because of, the application of consid-
erable technology. Thus, much might
be done for both the indigenous and
pioneer agriculturalist through the
assemblage of the available data base,
through the identification of missing
information by systems analysis,
through the filling of critical gaps by
experiment and field research, and
through the distillation of the final
product in such form as to provide
meaningful answers to the perennial
questions of farmers, ranchers, and
planners be they peasant or agro-
industrial producers.
Water-Saving Cultivation — A
number of the critical gaps in our
knowledge have already been identi-
fied. For example, data on water-
yield relationships in less than opti-
mal conditions are difficult to obtain.
We know for most plants how much
water they need to survive and how
much water they can use if water is
readily available, but we know little
about the trade-off between these two
points. The breeding of new varieties
has, to date, seemed to require more
rather than less water for the high-
yielding varieties; there seems little
widespread exploration in breeding
of the balance between yield and
water need.
Though some water-saving cultiva-
tion methods are widely practiced,
the actual effects of some measures
are disputed, partly because these
effects seem to vary greatly with soil,
slope, rainfall, and cultivation prac-
tice. For example, tie-ridging, a wa-
ter-conserving practice in semi-arid
tropical areas has a very mixed effect
depending on the crop, soil, slope,
and pattern of rainfall encountered.
The proper timing of planting or
grazing requires much more analysis.
The probability of below-average
rainfalls that might lead to drought
is calculated in certain standard ways,
usually involving the assumptions
that rainfall events are independent
and that the relative frequency or
some mathematical isomorphism of
historic events provides useful prob-
abilities of future expectation. But
neither of these approaches ade-
quately forecasts the persistence of
below-normal rainfall characteristic
of drought conditions in temperate
areas or the monsoonal delays asso-
ciated with drought in tropical areas.
Forecasts of persistence require
knowledge of the climatic mechan-
isms associated with the phenomenon
and forecasts of monsoonal delay re-
quire understanding of the associated
weather systems.
Irrigation — For a considerable part
of the world, irrigation represents a
crucial drought adaptation. But ir-
rigation efficiency is notoriously low;
the amount of water wasted prior to
field application from conveyance,
seepage, phreatophytes, or in misap-
plication is very high. For all of
these sources of water loss, the po-
tential contribution from applied re-
search is great.
Nevertheless, in many parts of the
world, water availability is far in
advance of water utilization because
farmers are slow to adopt the new
system. It is with irrigation, as with
the adoption of new hybrids or in the
choice of any new adjustment, that
the social sciences have a special
role in bridging the technical isolation
that characterizes much research and
development and in placing such
efforts into the ecological matrix of
farmers' life styles, agricultural sys-
tems, and socio-institutional settings.
For many farmers, acceptance of ir-
rigation literally means the accept-
ance of a new way of life. Thus, the
question is still wide open as to which
farmers make the best settlers for
the great new irrigation projects now
on the drawing boards of many de-
veloping countries. Or consider the
achievements of the Green Revolu-
tion. We are told that the rapid
adoption of high-yielding rice and
wheat, particularly in South Asia,
will give needed breathing space in
the critical Malthusian struggle for
survival. But we are warned that
such adoption comes at a cost of
further stratifying rural society and
intensifying existing trends that cre-
ate classes of prosperous landowners
and landless rural workers. An even
more complex social interaction is
found among farmers on the shores
of Lake Victoria who seem to be
shifting from drought-resistant millet
to bird-resistant maize because their
children, who formerly stayed in the
fields at harvest time to protect the
crops from bird pests, are now in
school!
All of the foregoing, the propen-
sity to adopt innovations, rural class
stratification, even bird pests, are
factors capable of analysis, if not
solution, within a framework of hu-
man ecological systems analysis. But
just as plant breeders have had to
develop strategies of genetic change
and varietal development capable of
providing new strains quickly, so
220
AGRICULTURE
must social scientists begin to de-
velop analytic frameworks capable of
accepting varied data and providing
better, if not the best, answers.
Priorities for Scientific Effort
Priorities for scientific effort de-
signed to broaden the range of choice
available to those who are subject
to recurrent drought can be listed as
follows:
1. The assemblage and analysis
of existing data in a systems
context and its preparation for
use in such form as to help
answer the agriculturists' pe-
rennial questions: where, what,
how, and when to plant or
graze?
2. A review of the relationship
between the development of
high-yielding varieties and their
moisture requirements, with a
view to developing cereal
grains combining drought-
resistance and higher-yielding
qualities.
3. A search for simplified forms
of systems analysis or critical-
path analysis capable of iden-
tifying crucial obstacles, needs,
niches, and interactions in agri-
cultural systems related to
broadening the range of
drought adjustment.
4. Improvement in the efficiency
of irrigation water use.
5. Review and analysis of existing
dry-land cultivation methods
with a view to improvement
and wider dissemination of
moisture-conserving tech-
niques.
Research on climatic and
weather systems is designed to
provide better forecasts of per-
sistence in temperate areas and
monsoonal delay in tropical
areas.
The thrust of these suggestions
is in application, to make more use
of what is already known through
synthesis and systems analysis or
simply scientific review, to seek a
marked advance through social sci-
ence technique in the adoption of
what we already know, and to seek
selected new knowledge where the
gaps in existing knowledge are great
or the opportunities seem particularly
rewarding.
221
PART VIII
AQUATIC
ECOSYSTEMS
1. COMPONENT RELATIONSHIPS
Trophic Dynamics, with Special Reference to the Great Lakes
Trophic dynamics is that kind of
ecology which concerns itself with
energy flow through the component
organisms of an ecosystem. The ul-
timate source of energy for any living
system is, of course, the sun. Green
plants, converting the sun's radiant
energy into chemical energy, are said
by ecologists to constitute the first
trophic level within an ecosystem.
All photosynthetic plants, regard-
less of systematic affinity, are thus
grouped together by ecologists be-
cause they all perform this same
basic function.
Animals that subsist largely by
eating green plants constitute the
second trophic level, be they aphid or
elephant. Their energy source is
once-removed from the initial fixation
of radiant energy. Although animals
of this trophic level are referred to
by ecologists as "primary consum-
ers," the lay term "herbivore" is of-
ten useful. Carnivores that prey
largely upon herbivores of any sort
constitute the third trophic level.
There are usually no more than
five trophic levels in an ecosystem
because the inevitable loss of energy
in the shift from one trophic level
to the next higher means that the
total energy contained in the bodies
of organisms on the fifth trophic
level is small relative to the first.
This relatively small amount of en-
ergy at the top level is disposed
into a small number of large and
usually widely dispersed bodies, since
there is a tendency for the predators
at the top levels to be larger than
their prey. (See Figure VIII— 1)
While the fifth level is often
reached in marine ecosystems, in the
Great Lakes it is not. Large lake
trout feeding upon fish would be the
top predators in the open-water com-
munity. They operate on the fourth
trophic level. Smaller lake trout often
subsist largely on small crustacean
herbivores; they would be assigned
to the third level. Roughly speaking,
about half of the living material in
a large lake at any one time resides
in the tiny cells of the numerous
photosynthetic algae — the first level.
In lakes as large and deep as the
Great Lakes, the overwhelming pre-
ponderance of life is found in the
open waters — away from the shore
and bottom. Yet it is still desirable
to refer to this assemblage of life
in the open waters as a "community,"
not an "ecosystem," because the open
waters lack full representation of
still a different trophic category —
"reducers." Reducers is the term
ecologists apply to the variety of
bacteria and fungi that derive their
energy from the complex molecules
in the dead bodies and feces of other
organisms of the system. Energeti-
Figure VIII- 1 — TROPHIC LEVELS
The figure illustrates an ecological pyramid showing various trophic levels. The
higher the step in the pyramid, the fewer the number of individuals and the larger
their size. In some environments, large animals circumvent some of the levels
in the food chain. For example, man takes from all levels below himself, including
that of the producers.
225
PART VIII — AQUATIC ECOSYSTEMS
cally speaking, this biological reduc-
tion is excessively wasteful, but the
small molecules that result from this
degradation can be utilized by the
photosynthetic plants, and thus re-
enter the trophic levels discussed
above. It must be stressed, however,
that a not inconsiderable amount of
reduction of dead algae and the
abundant feces of the animal plank-
ton occurs as these sink slowly
through the depth of the water.
There is thus a recycling of biologi-
cally active elements within the
water body itself, not dependent
upon the seasonal recurrence of full
vertical circulation and the cool-
season reintroduction of the accu-
mulation of the products of reduction
on the bottom back into the open-
water system of temperate lakes.
Contrasting Trophic Dynamics in
Terrestrial Systems — Comparison of
some of the basic attributes of the
open water of a great lake, or of
the ocean itself, with those of a well-
developed terrestrial system such as a
forest reveals some basic dissimilar-
ities. The general features of trophic
dynamics sketched at the outset ap-
ply, of course, with equal validity
to terrestrial and aquatic systems.
The dissimilarities arise from the
differences in the structure of the
dominant green plants.
Individual producers of the forest
attain great size, each striving to
spread its photosynthetic apparatus
so that it may be fully exposed to
the sun, unshaded by its neighbors.
The trunk and branches by which
each forest tree maintains its leaves
in the sun provide, in the aggregate,
a rigid three-dimensional framework
in relation to which the other or-
ganisms of the system dispose them-
selves. The leaves are the food source
for aphid and caterpillar, sloth and
deer, tapir and gorilla. The per-
manent woody plexus has made it
possible for this variety of sizes of
herbivores to evolve, each achieving
a different way of exploiting the
same food resource but each small in
size compared with the green plant,
some part of which each consumes.
How differently the photosynthetic
apparatus is disposed in the Great
Lakes! Here the individual plants
are tiny — microscopic solitary algal
cells or clumps and colonies just vis-
ible to the unaided eye (or, when
dead or moribund, evident to both
eye and nose as floating scum). The
principal herbivores in the open wa-
ters are small crustaceans, large com-
pared to the individual algal cells
that constitute their major food, but
often too small to cope with large
clumps of algal cells.
To photosynthesize, the algae must
be in the upper, lighted water layers.
Under ice, algae are often concen-
trated at the very top of the water,
but in warm seasons they are swept
around in the Langmuir spirals in-
duced by the wind moving over the
water's surface. When wind is
strong and temperature low, the
spiral currents may carry the algae
too deep for adequate light to pene-
trate. But during the warmer half
of the year the myriad cells of the
phytoplankton are slowly spiralled
through the well-lighted, warmer
layer of lake water. Quite unlike the
forest situation, the green plants of
the open water display no semi-
permanent, three-dimensional pattern
of structure in relation to which ani-
mals can orient themselves and
evolve special behavior patterns. The
open waters provide no place to hide!
One reason to stress the differences
between these two kinds of commu-
nities is that man, the observer, is
primatively a member of a forest or
grassland community, and some ecol-
ogists have too much betrayed their
experience of the forest in their in-
terpretation of the dynamics of open-
water systems. A part of this dif-
ficulty of interpretation has been the
tendency to expect, in essentially
structureless open-water systems, the
same kind of fine-grained adjust-
ments of organism to environment
that have evolved in the substratum-
dominated terrestrial systems.
Man-Induced Disturbances — The
nature of the dynamic model of rela-
tionships within the open-water com-
munity of the Great Lakes is of more
than academic concern. Man has
seriously disturbed the biotic prop-
erties of these lakes by his multi-
farious activities. If the quality of
these lakes is to be improved and
continuously maintained at an im-
proved level, a correct and complete
understanding of the ecological inter-
relationship is required.
The overgrowth of the algae in
Lake Erie is probably the most ob-
vious manifestation of the disturb-
ances that the biological communities
of all the lakes have sustained to
varying degrees. An algal over-
growth, or, in ecologists' terms, an
increased standing crop of the phyto-
plankton, is a characteristic recent
manifestation of lakes in Europe and
North America on the shores of
which large concentrations of human
populations reside.
The biological waste produced by
the people of cities is biologically
reduced, to varying degrees, into
small molecules of biologically active
elements such as nitrogen and phos-
phorus. When these are flushed into
lakes directly, or into their tribu-
taries, they augment the natural sup-
ply of plant nutrients.
This "cultural enrichment" of lakes
is cumulative. Once the simple com-
pounds of nitrogen and phosphorus
enter the lake in solution, they are
quickly and effectively taken up by
the green plants — the phytoplank-
ton as well as the rooted water plants
along the shore. Henceforth, these
elements will reside in the complex
molecules of organisms. They spend
but little time in solution in the lake
water; the amount of nitrogen and
phosphorus that will escape through
a lake's outlet, dissolved in the water,
is remarkably small compared to that
226
COMPONI. ONSHIPS
leaving the lake in the tissues of
emerging insects or organisms other-
wise removed from the lake.
Approaches to Quality
Management
Management of lakes to maintain
quality seeks two goals, both of
which involve maximizing the rate
at which the energy-rich compounds
of nitrogen and phosphorus fixed in
algae are passed to higher trophic
levels. One goal is to reduce the
standing crop of phytoplankton,
thereby making the water more trans-
parent; the second is to find an eco-
nomical way to remove nitrogen and
phosphorus from the lakes.
The third trophic level in the open-
water community is the lowest at
which nitrogen and phosphorus are
concentrated into packets of a size
that man can manipulate and use.
These "packets" are the bodies of
the fish that eat the animal plank-
ton; they can be fished from the
lake and used directly as human
food (as lake whitefish once were in
large amounts) or they can be used
as a protein source for animal nutri-
tion (as alewives can be).
We began this discussion of man-
generated changes in lakes by sug-
gesting that our conception of trophic
dynamics within the open water is
crucial to attempts to redress some
of these biological imbalances. There
are two alternate concepts of these
relationships (to be sketched below).
They differ in their relevance to
achieving the two management goals
set out above. The more recent for-
mulations stress the role of predation
by plankton-eating fish in control-
ling the species composition of the
plant and animal plankton. This con-
cept offers hope that the two goals
are not only compatible but might
be achieved by the same manipula-
tions of the system. On the other
hand, the older concept — which
stresses competition within a trophic
level as the prime determinant of
plankton composition — presents no
simple dynamic model of relation-
ships among the first three trophic
levels. Attempts at management of
disturbed lakes will, therefore, not
only hope to achieve practical goals
but also to test and extend the con-
ceptual models.
The Scientific Data Base
In general, the data base for evalu-
ating and extending knowledge of
the trophic dynamic systems of the
Great Lakes is inadequate. This dy-
namic approach demands knowledge
of the interrelationships of the ele-
ments of the lake ecosystem, while
all that is now available are unre-
lated segments of data concerning
various aspects of the ecosystem.
Data on the seasonal changes in the
physical and chemical parameters for
more than a few stations at a time
in any one lake have become avail-
able only within the past decades.
Attempts to relate these physico-
chemical to biological changes have
only been sporadic. Of the biologi-
cal data, that on changes in the com-
position of the fish stock is probably
most nearly adequate. That on the
plant and animal plankton, which
comprise the bulk of the biomass, is
spotty and inadequate. A recently
published bibliography of the Great
Lakes plankton studies lists over 400
papers, but, as the bibliographer
added,
The biology and ecology of the
plankton remains poorly known.
Most papers are descriptive and
concentrate heavily on taxonomy
and distribution of certain orga-
nisms. Experimental work on the
dynamics of Great Lakes plankton
is urgently needed in light of rap-
idly changing environmental con-
ditions and fluctuating fish stocks.
The last sentence makes the essential
point: Significant studies of the
trophic dynamics involve simultane-
ous studies of physico-chemical pa-
rameters, the phytoplankton, the zoo-
plankton, the planktivorous fi
the piscivores.
Various bits of work done recently
in Lake Michigan can be put together
to provide some insight into the
trophic dynamics of that lake. This
has provided the reassuring informa-
tion that changes in the composition
of the animal plankton following
changes in stocks of planktivorous
fish (establishment of alewives, to be
specific) have been precisely what
would be predicted from knowledge
of the dynamics of much smaller
lakes. Furthermore, the time required
for the changes to be manifest in the
animal plankton of Lake Michigan
is not inordinately greater than the
time required in smaller lakes. This
is not surprising, because the total
size of the system should be less
significant than the mean ratio of
planktivore/zooplankter.
Theoretical Formulations:
Control from Above
A recent theoretical formulation
states that the composition of the
first trophic levels in the open-water
communities of large lakes is deter-
mined in large measure by the selec-
tive feeding habits of the planktivo-
rous fish. The prey selections by the
schools of zooplankton-eating fish
directly determine the species com-
position of the animal plankton. This
indirectly affects the quantitative and
qualitative composition of the phyto-
plankton (algae, bacteria) because
species of animal plankton differ in
the effectiveness with which their
populations can collect algae and
other small particles from the lake
water.
Large crustacean zooplankters of
the genus Daphnia play a crucial role
in the indirect control of the first
trophic level resulting from the selec-
tive feeding of the third level. The
large Daphnia are both the favorite
food of freshwater planktivores and
the most effective collectors of small
particles (1-50 microns) from the
227
PART VIII — AQUATIC ECOSYSTEMS
medium. When planktivore stocks
are sufficiently high, the populations
of large Daphnia are reduced to in-
significant numbers. Since the smaller
crustacean competitors that replace
them (see Figure VIII-2) are less
effective in collecting small algae, the
algal populations will tend to in-
crease, making the lake water less
transparent.
This theory, in essence, states that
the composition of the open-water
community is determined by the
trophic actions of the highest (third
and fourth) trophic levels. The for-
mulation suggests a management
concept for controlling the effects of
the continued enrichment pollution
of the Great Lakes. In essence, the
plan would be to reduce planktivore
pressure in such a way as to maxi-
mize the populations of Daphnia
which are most effective in removing
algae from suspension. The plank-
ton-eating fish could be removed by
man through fishing. Removing the
fish would remove some "packets"
of nitrogen and phosphorus in the
lake ecosystem at the same time as it
permitted the proliferation of Daph-
nia. The fish themselves, depending
on their species, could be variously
used as human food, animal food, or
as a source of oils and other material
for chemical manipulation.
The stocks of planktivores could
also be kept in check by introducing
and manipulating stocks of piscivo-
rous fish. For example, the introduc-
tion of coho salmon into Lake Mich-
igan is an attempt at controlling the
burgeoning population of the alewife
(Alosa pseudoharengus — originally
a marine planktivore that, despite its
abundance in many freshwater lakes,
is still imperfectly adapted to the
peculiarities of a freshwater exist-
ence). While this method of con-
trolling planktivores has the ad-
vantage of permitting the nitrogen
and phosphorus to be removed in
large packets that tend to find greater
acceptance as human food, the total
amount of these elements that could
be extracted from the fourth trophic
level of the lake is at most one-
seventh of that which could be re-
moved via the third. It is thus less
satisfactory as a means of decreasing
the total amount of nitrogen and
phosphorus from a lake than is re-
moval of fish from the third (plank-
tivore) level.
The entire matter of the use of
the fish removed from the Great
Lakes as food for man or beast has
been complicated by the fact that
various stable and toxic chlorine-
containing compounds such as DDT,
DDD, DDE, and PCB's are concen-
trated in the oil and body fat of the
fish of both trophic levels.
Theoretical Formulations:
Control from Below
In contrast to the concept of con-
trol of the composition of the open-
water community indicated above,
the alternate concept — widely held
a decade ago — still has adherents.
The control-from-below theory en-
visions the composition of the com-
munity as being primarily determined
by competition within each trophic
level. In this view, the composition
of the first level — phytoplankton —
is determined by the particular con-
figuration of physico-chemical con-
ditions at the season in question.
The species composition of the sec-
ond level — zooplankton — is deter-
mined primarily by competition
among populations of the various
species of crustaceans and rotifers
that could occur within the lake for
the kinds of phytoplankton thriving
at that moment. Each species is most
effective in collecting only a portion
of the total range of sizes and kinds
of algae available. The planktivores
feed on whichever species of zoo-
plankter is available at the time.
It can be appreciated, therefore,
that changing the intensity of plank-
tivore predation upon the zooplank-
ton would be expected, by the
control-from-below hypothesis, to al-
ter the total quantity of zooplank-
ton — but not necessarily its specific
composition. Since this concept does
not consider that planktivore preda-
tion has any pronounced effect on
the species composition of the zoo-
plankton, there is no theoretical basis
for attempting to modify the com-
position and standing crop of the
algae by manipulating the stock of
planktivorous fish.
Requirements for
Scientific Activity
Examination of the simultaneous
changes in the abundance of all the
various species that comprise each
trophic level is necessary to evaluate
the alternative concepts of trophic-
dynamics outlined above. This is an
enormous task, even in the Great
Lakes where the variety of species
on all levels is very much less than
it would be in an equal volume of
the ocean.
The greatest difficulties of enumer-
ation and categorization are pre-
sented by the extremely numerous
small organisms of the plankton.
Automatic methods of counting the
plankton and categorizing them ac-
cording to size must be developed.
The Coulter method of counting and
sizing particles by the drop in elec-
trical potential that each generates
while passing through a small aper-
ture through which an electric cur-
rent passes is not entirely satisfac-
tory. This data must be stored
electronically so as to be immediately
available for use with data on phys-
ico-chemical conditions, on the one
hand, and data on the characteristics
of the fish populations, on the other.
In addition to methods of auto-
matic data collecting, it will be nec-
essary to make provision for the
proper taxonomic assignment of spe-
cies of the plant and animal plankton.
This information, gathered from ali-
quots, must be applied to the auto-
matically acquired data on size
categories. At present this is an
operation that is tedious at best and
nearly impossible at worst.
228
COMPO\i TIONSHIPS
Figure VIII— 2 — EFFECT OF ALEWIVES ON ZOOPLANKTON
15
" 10
1942— WITHOUT ALEWIVES
LENGTH 0-4
mm.
= Cut Off
Epischura \\
Yellow
Perch
DOMINANT
ZOOPLANKTERS
Diaptomus
Cyclops
16 -
964— WITH ALEWIVES
Leptodora
5 mm.
Mesocyclops
UPPER
LIMIT
1.0
DOMINANT
ZOOPLANKTERS
The histograms show the distribution and composition of crustacean zooplankton
(as well as one predatory noncrustacean) before and after a population of Alosa
pseudoharengus (alewives) became well established. The arrows indicate the
size and the position in the distribution of the smallest mature instar of each
dominant species. Such larger zooplankton as Daphnia were present, but they
represented less than one percent of the total sample count. The triangles denote
the lower limit or cut-off point of the zooplankton consumed by the several
species of fish indicated. Note that with the advent of the alewives, the size
distribution of the zooplankton was depressed significantly to smaller species.
229
PART VIII — AQUATIC ECOSYSTEMS
Seasonal changes as well as natural
and man-induced changes in the
fish stocks continually perturb the
lake ecosystem. Continuous analysis
of the perturbations of the plant and
animal plankton should make it pos-
sible to evaluate the concepts of
trophic dynamics, leading to the de-
velopment of techniques and concepts
necessary for managing the Great
Lakes so as to maximize both water
quality and fish yield.
The primary requirement is the
assembly of a scientific staff together
with the equipment and instrumenta-
tion (ships and collecting gear) nec-
essary for collecting extensive sam-
ples. The samples should be converted
into data as automatically as possi-
ble. Taxonomic identification services
should be established. Methods for
data storage and rapid retrieval
should be developed. Much could
be done within five years toward the
development of effective manage-
ment concepts if a concerted effort
were made along these lines.
Effects of Artificial Disturbances on the Marine Environment
The capability of predicting the
specific consequence of a general
disturbance of a natural community
is basic to planning and evaluating
environmental controls. Large sums
of money and considerable effort
could be saved if we could foresee
the effects of a particular human
activity.
History has taught us what to
expect from the destruction of forests
and prairies. But we cannot now
predict, with any confidence, more
subtle disturbances or the long-term
cosmopolitan consequences of drastic
change. This circumstance is rapidly
changing. Recent theoretical devel-
opments have directed our attention
to new ways of looking at the prob-
lem. There is reason to believe that
it will soon be possible to predict
change, at least in relatively simple
ecosystems such as exist in the sea.
Ecological Generalities
Few long-term studies have been
made on the changes that occur in
natural communities. We must there-
fore rely more on theory than ex-
perience. It is now recognized that
there is a fundamental relationship
between the number of species, the
number of individuals of any spe-
cies, and the stability of the environ-
ment. For example, there are fewer
species with relatively larger numbers
of individuals in severe or unstable
environments than in environments
whose fluctuations are predictable.
If the environment becomes more
stable in time, the number of species
increases. If the environment is dis-
turbed in any way, the number of
species decreases.
Succession and Regression —
Around the turn of this century
ecologists recognized that, wherever
a land surface was laid bare, it was
colonized by species in a regular
order. It was possible to predict, on
the basis of previous observations,
which species of animals and plants
would appear first and which would
later replace the earliest immigrants.
This process of succession of one
natural community by another con-
tinues until a stable climax commu-
nity is reached. However, succession
is a reversible process. Any disturb-
ance will drive the climax community
down to a lower level of succession.
The disappearance of species is also
in a more or less regular order.
If we had data on the changes in
all natural communities, we could
predict the consequences of a general
disturbance using the principle of
succession. In the absence of such
studies, there may be another way
of obtaining relevant data: There is
evidence that natural communities
are continually responding to local
variations in the stability of the en-
vironment. Small-scale disturbances
drive down part of the system with-
out appreciably affecting other areas.
If this is the case, a community can
be viewed as a temporal mosaic, por-
tions of which are at different levels
of succession. In this circumstance,
the variations in species composition
observed in space could be similar
to those observed in time. If samples
taken throughout a natural commu-
nity at one time are placed in order
of diversity, the array should simu-
late the order of species appearance
or disappearance in succession or
regression.
The Impact of Pollutants
At least some of the changes asso-
ciated with pollution resemble those
observed in natural sequences. For
example, the order in which marine
species disappear as a sewage outfall
is approached is often the reverse of
the order in succession. Using this
principle, we can take samples
throughout an area, arrange them
in order of diversity, and predict the
changes that would occur in the
vicinity of a proposed outfall.
Some pollutants and other types of
disturbances are probably specific in
their effects upon communities, af-
fecting some species more than oth-
ers. Prediction in these cases will
require knowledge of the physiologi-
cal responses of particular species to
the particular compound or disturb-
ance. However, where the disturb-
ance is general, as in pollution from
domestic sewage or dredging, we
should be able to predict the effects
upon the community using the kinds
of observations and samples now
taken by ecologists.
Prediction in Shallow-Water Com-
munities— Simple communities, low
230
in diversity, are strongly influenced
by stresses imposed by the physical
environment. Complex communities,
high in diversity, tend to be more
stable and integrated. It should be
easier to predict change in the sim-
pler, physically controlled communi-
ties than in the complex, biologically
controlled associations.
Marine communities in shallow
water appear to be simpler than those
in deep-sea and terrestrial environ-
ments. Therefore, the planktonic and
benthic marine communities in shal-
low water offer the greatest oppor-
tunities to test hypotheses concern-
ing succession and the relationship
between environmental stability and
diversity. This is fortunate, since
these communities are of great eco-
nomic importance and yet suffer the
greatest exposure to artificial disturb-
ances. If we can perfect methods of
prediction in shallow-water commu-
nities in the next several years, there
will still be time to develop the
economic and political institutions
needed to prevent the wholesale de-
gradation of these important eco-
systems.
Needed Scientific Activity
In the next several years we will
need to perform field and laboratory
experiments explicitly designed to
test the growing body of ecological
theory. For the purpose of develop-
ing our prediction capability, we
should perform such experiments in
areas that are undergoing or about to
undergo artificial stress.
Ecological surveys are now com-
monly made in connection with pro-
posed reactor installations or sewage
outfalls. While such studies vary
tremendously in quality, most are
worthless. Most are poorly designed
without any regard to previous ex-
perience or theory. It is not possible
to generalize from the data obtained
from most of these surveys because
of the great differences in the meth-
ods of sampling and analysis used.
One of the most pressing needs in
applied marine ecology is the devel-
opment of high and uniform stand-
ards for the performance of routine
ecological surveys.
Monitoring — At the state and na-
tional level, it would be highly de-
sirable to develop programs to moni-
tor environmental events. We could
maximize the use of data obtained
from the study of artificial disasters
if such studies were performed by
highly trained teams of observers.
High school and college biology
teachers might be enlisted in this
effort. It would not be difficult to
cover the coastlines of highly popu-
lated areas such as California. Cen-
ters for environmental control could
be established to train teams of ob-
servers, to develop standards of per-
formance, and to collate and analyze
data. Such data would be of immeas-
urable value in designing basic re-
search programs and in developing
environmental controls.
Research and Training — On a
long-term basis, we must continue to
support basic research in population
dynamics. In shallow-water commu-
nities there is a particular need to
place more emphasis on larval re-
cruitment. Our understanding of the
temporal changes in benthic marine
communities is severely limited by
riONSHIPS
our lack of knowledge
ecology.
It is essential to expand research
and training in systematic biology.
Systematics remains as the founda-
tion of nearly all ecological research.
Yet our attempts to attract talent and
support in these areas are feeble.
The major museums of this country
should be the focal points of this
effort, but they are suffering decay
and neglect.
Scientific Preserves — In the long
term, it is important to establish large
scientific preserves to serve as stand-
ards of environmental quality, as
natural laboratories, and as sources
of larvae for the maintenance of
species elsewhere. We must begin
this program as soon as possible, for
few areas remain suitable for these
purposes along our coasts.
In conclusion, there is reason to
believe that we will have a limited
capability of predicting changes in
natural communities within the com-
ing decade. This capability will be
greatly expanded by the rapid devel-
opment of ecological theory and the
performance of critical experiments
in natural communities. To achieve
these goals, we should increase basic
research in systematic biology and
population dynamics, establish scien-
tific preserves, and develop programs
to monitor environmental events. If
we begin now, we may be able to
halt the degradation of the marine
environment as early as 1990. If we
do not begin now, we will reduce the
natural communities along our coasts
to a level where their contribution to
our economy and general welfare will
be trivial.
Marine Flora and Fauna in the Antarctic
The environment of the antarctic
seas is less variable than that of
temperate latitudes with respect to
temperature and salinity, but the
quality of light throughout the year
may be quite different because of the
long periods of light and dark and the
winter ice cover. In many parts of
the antarctic, especially near the con-
tinental margin, the temperature
of the ocean water is near 0" cen-
tigrade or below, and nowhere in
the regions known as "antarctic" —
that is, south of the Antarctic Con-
vergence— are surface waters warmer
than 1.0° centigrade. In deeper water
the temperature is almost constantly
around —1.8° centigrade. As the
Canadian biologist Dunbar has
pointed out, a cold constant tempera-
ture is not a limiting factor for the
231
PART VIII — AQUATIC ECOSYSTEMS
development of life, and the antarctic
seas are rich and immensely produc-
tive, at least near the surface and at
shallow depths.
Marine Life of Special
Interest to Man
Oxygen and nutrients are high in
these cold waters, as might be ex-
pected from the abundance of life in
them. Two centuries ago man drew
heavily on the stocks of seals of the
sub-antarctic islands; more recently,
he has reduced the stocks of blue
whales to such low levels that it is
no longer economical to pursue them.
Recently there have been discus-
sions of utilizing the vast populations
of the krill, Enphausia superba, which
are the principal food of the blue
whales, the Adelie penguins, and
several kinds of fishes. It is esti-
mated that the total populations of
krill are equal to all the rest of the
fisheries of the world, at least in gross
tonnage, or about 60 million metric
tons. However, the krill occurs in
patches and the small size of the
individuals poses difficult processing
problems. Also, the animals are
"tender" — that is, they must be
processed immediately. For these
reasons, immediate extensive use of
this resource appears unlikely. Among
other significantly abundant fishes
are representatives of the family
Nototheniidae; these are currently
being fished on an experimental basis
by the Soviet Union.
There seems to be less fisheries
potential in the shallow-water or sea-
bottom life, which is often abundant
and varied but lacks the extensive
beds of large bivalves found in arctic
waters. Large seaweeds are abundant
around the sub-antarctic islands and
near the shores of the Antarctic
Peninsula, and invertebrate popula-
tions are large in the vicinity of
McMurdo Sound and the Soviet base
in the Davis Sea. Most of the as-
semblage consists of such organisms
as sponges, bryozoa, and echino-
derms, of little potential commercial
value. The bottom fauna is of con-
siderable theoretical interest because
of its apparently stable or slowly
changing composition, at the same
time combined with a diversity of
components comparable to that of
the Indo-Pacific coral reef environ-
ment.
The rates of turnover or replace-
ment of the antarctic fauna have yet
to be worked out in the detail neces-
sary for rational harvest of the fish-
eries stocks, but the unfortunate his-
tory of the blue whale suggests that
our relations to the fishery resources
of the antarctic will be governed pri-
marily by socio-economic rather than
ecological considerations. That is, we
will simply fish until stocks are so
reduced that it becomes unprofitable
to expend the effort and funds neces-
sary to keep the catch up.
Examples of Adaptation
The adaptations and peculiarities
of the flora and fauna of the shallow
waters near the antarctic continent
are of great scientific and theoretical
interest. Two of the most interesting
concern the adaptation of fishes to
water that is below freezing by the
production of a sort of natural anti-
freeze substance (according to one
researcher) or to a higher concentra-
tion of salt in the blood (according to
another); other fish adapt to the low
temperature and high oxygen by de-
veloping the ability to function with-
out hemoglobin. The disagreement
between deVries, who finds that cer-
tain fishes may resist freezing because
of a protein containing carbohydrate
in their blood, as contrasted with
Smith's observation that this is ef-
fected by increased salt, should stim-
ulate more intensive and critical work
on the blood of antarctic fishes.
The adaptations of the Weddell
seal, the southernmost mammal, are
of particular interest. This animal is
capable of diving for periods of more
than 40 minutes to depths of 400
meters (about 1,200 feet), can swim
under water for at least two miles,
and has excellent sense of direction
under water. A thorough understand-
ing of the physiology of this mammal
will help us to understand the prob-
lems of diving, which is an increas-
ingly significant activity in man's ex-
panding use of the sea.
Status of Scientific Activity
At the present time there is con-
siderable interest in the nature and
significance of diversity in the sea —
that is, whether a high ratio of differ-
ences to total numbers of all kinds or
abundances is related to a situation
that may be in equilibrium or indica-
tive of a long-established condition,
or whether, conversely, a low pro-
portion of different kinds of species
indicates recent, temporary, or chang-
ing conditions. Many pollution pro-
grams are predicated on the idea that
diversity may be associated with
stable and presumably favorable or
optimum conditions. As yet we lack
adequate data to ascertain whether
or not diversity exists and what it
may signify, especially for situations
at the bottom of the sea.
The benthic environment of the
antarctic should provide us with use-
ful information on this controversial
problem because it appears to be a
comparatively unchanging environ-
ment with a rich variety of species.
The problem will require a more in-
tensified level of field ecological work
on a year-round basis than is being
done at present, at least by U.S. re-
searchers. It is in this area that
theoretical formulation and mathe-
matical modeling (already being at-
tempted for situations in other re-
gions) would be most appropriate,
but we still lack the data base. For
example, we are still unable to evalu-
ate data concerning diversity in dif-
ferent regions of the antarctic.
Physiological aspects seem to be
much better in hand; a concerted
attack on some of these problems is
232
COMPONENT RLI.ATIONSHIPS
under way by a group on board the
R. V. Alpha Helix.
Instrumentation — We are reason-
ably well equipped, especially in
physiology, to undertake antarctic
studies, although details of apparatus
can always be refined. One problem
that seems to plague divers in partic-
ular is the vulnerability of photo-
graphic equipment in the cold antarc-
tic waters; various kinds of seals
continue to break down and put
cameras out of commission. We
need some functioning under-water
photomonitoring systems for the
dangerous antarctic waters in order
to obtain information under winter
conditions near the bases.
Manpower — Our principal re-
quirement is interested manpower in
order to expand field ecolog
grams in the next five years b
duce data relevant to theoretical
ideas in ecology at a scale to keep up
with such work elsewhere. Obvi-
ously, there is need for some sort of
ecological monitoring to help us
check on the worldwide deterioration
of our environment. In the antarctic,
this activity would also provide data
of basic and theoretical importance.
Systems Approaches to Understanding the Oceans and Marine Productivity
The ability of man to affect the
biological character of the near shore
regions is universally recognized;
polluted harbors and lagoons turn
blue water to green from enhanced
production of algae. Man's ability to
add potentially significant quantities
of manufactured materials, some of
which are biologically active, has
been acquired only recently, and rec-
ognition of this ability has been
startling to scientists and laymen
alike. Nevertheless, this unpleasant
news is true, with DDT providing
the most spectacular and potentially
harmful example recognized so far.
However, large quantities of an indus-
trially useful class of chemical com-
pounds, polychlorinated biphenyls
(PCB), are also being added to the
sea.
The DDT experience suggests that
the marine ecosystem is highly vul-
nerable in two areas: (a) the micro-
scopic plants or phytoplankton that
form the basis for the biological
productivity of the sea, and (b) the
reproductive stages of marine ani-
mals, beginning with those grazing
on the phytoplankton and extending
as far as the birds.
The phytoplankton, as the green
plants of the sea, are intimately in-
volved not only with the production
of food organisms in the sea but with
atmospheric processes as well — for
example, the production of oxygen
and the absorption of carbon dioxide.
The optical qualities of the sea sur-
face also are strongly influenced by
the amount of phytoplankton pres-
ent. Preliminary experiments and ob-
servations suggest that the range of
sensitivity of marine phytoplankton
extends to concentrations as low as
one part per billion, coinciding nicely
with man's current capacity to add
exotic materials to the sea. Figure
VIII— 3 illustrates this sensitivity.
The role of the ocean as a source
of food, especially of protein, and as
a means of livelihood for fishermen
needs no elaboration. Large-scale
changes in the level of production of
phytoplankton or in species composi-
tion are certain to be reflected rapidly
in the populations of fish. Other eco-
nomic and health considerations arise
in connection with the pollution of
the sea near bathing beaches.
The Status of Simulation Modeling
From the foregoing discussion, the
marine ecosystem appears as a com-
plex biological system interacting
with its immediate physical environ-
ment and with the atmosphere. The
use of high-speed digital computers
in conjunction with simulation models
of oceanic productivity and of sub-
units such as coastal regions and
upwelling areas is now possible; it
offers the only real hope of obtain-
ing predictive capacity for this im-
portant ecosystem.
Although the many observations
of plant productivity made in the
past twenty years have yielded re-
liable general patterns, the dynamics
of marine production is poorly un-
derstood. The simulation model
approach has been discovered by
biological oceanographers relatively
recently, largely as a result of the
U.S. effort in the International Bio-
logical Program. One interdiscipli-
nary group involving meteorologists,
physical oceanographers, biological
oceanographers, and fisheries experts
is engaged in the construction of a
series of simulation models of upwell-
ing regions, where a disproportion-
ately large share of the world's fish-
eries resources are located. This
group appears to be the only one
engaged in a serious program of this
nature.
The relatively strong field of the-
oretical physical oceanography has
provided a mathematical basis suf-
ficiently sound to enable at least one
computer simulation model of the
Pacific oceanic circulation to be built,
with the result that all known cur-
rents appear with approximately the
correct transport rates. Such models
can provide the necessary hydro-
dynamic base for ocean ecosystem
models. However, a large part of the
theoretical formulation necessary for
biological modeling has never been
developed to a satisfactory degree.
Recently, a considerable amount
of productive research has been car-
ried out in which the sea is examined
from the viewpoint of continuous
culture theory, the latter studied in-
tensively for industrial and sewage
233
PART VIII — AQUATIC ECOSYSTEMS
Figure VIM— 3 — SENSITIVITY OF PHYTOPLANKTON TO INSECTICIDES
100 r-
O
0.01 0.1 1 10 100 1.000
INSECTICIDE IN WATER (ppb)
The left-hand charts show the uptake of ' 'C by phytoplankton as a function of
the concentration of several insecticides. At concentrations greater than one
part per billion (ppb) in three of the four species studied, the reaction in uptake
is great. The right-hand charts show the effect of adding 100 ppb of DDT and
endrin to water containing several types of phytoplankton. The insecticides were
added each day for 7 days and solvent was added in equal volume to the controls.
The insecticides significantly reduced production in three of the four species
under investigation.
treatment applications. Through this
line of research, some of the results
of the intensive activity in biochem-
istry and molecular biology are being
incorporated into biological oceanog-
raphy, and satisfactory calculation
models for the absorption of nutri-
ents by phytoplankton are being de-
veloped rapidly. Since phytoplankton
production is limited in most regions
of the sea by the rate at which
nutrient-rich waters from below are
brought to the surface by hydrologi-
cal processes, the equations linking
phytoplankton production and basic
hydrological parameters of the ocean
circulation are virtually at hand.
From this point on up the food
chain, the situation deteriorates. Little
useful information exists on rates of
grazing by the zooplankton, the small
animals intermediate between most
fish and phytoplankton. At this level,
animal behavior must be taken into
consideration and reproduction pat-
terns become important. Although
general patterns are known, the de-
tails remain to be filled in and are
largely lacking for modeling pur-
poses. The structure and behavior
of some fish populations is better
known as a result of the pressure of
economic value, and simulation mod-
els have been developed that are use-
ful in the management of specific
fisheries. These models, however, are
not linked in their present form to
the food chain supporting the fishery.
Efforts are currently under way to
form this link, using the Peru an-
chovy fisheries as a basis. In some
of the advanced simulation models,
the response of fishermen to various
regulation regimes is taken into con-
sideration.
Future Requirements
A library of simulation models of
oceanic productivity is needed to
deal with the problems posed by
man's intervention. Some models
should be designed to give large-
scale coverage without great detail —
for example, models of each of the
234
COMP( I \riONSHIPS
major oceans. Others are required
for specific coastal regions and, fi-
nally, for specific estuaries. Within a
geographic class, models will be
needed for specific purposes in addi-
tion to at least one base model pri-
marily describing plant-environment
effects. The addition of such models
to the tools presently available to
managerial personnel and policy-
makers at the international, national,
and local levels could be one of the
most important steps to be taken in
the near future.
Although it is difficult to predict
the amount of time required to build
these models, some of them should
be operational within the next five
years. Obviously, the potential dan-
gers inherent in an inaccurate or
incorrect model are great, and it is
absolutely essential that careful con-
sideration be given to validation, a
step that is almost certainly more dif-
ficult than building the model.
If the models are to be useful,
provisions must be made for collect-
ing the required input data. Although
it is not usually possible to specify
these requirements with accuracy un-
til the models are built and running,
intelligent guesses can nevertheless
be made; and if serious modeling ef-
forts emerge, they should be made
available to the various environ-
mental monitoring programs such as
GNEM (Global Network for Environ-
mental Monitoring) at an early date.
The potential of the simulation mod-
els for the detection of anomalous
conditions should not be overlooked;
perhaps it is not too early to propose
the use of simulation models for
monitoring to GNEM and other plan-
ning groups. Monitoring possibilities
are especially attractive at the local
level. For example, the deviation of
the pattern of the phytoplankton
plume produced by a marine sewage
outfall from that predicted by a vali-
dated model might be used to indi-
cate that a toxic compound of a
certain class had been introducd into
the collection system; the approxi-
mate quantity might be indicated as
well.
The resources for carrying out the
necessary research and computer pro-
gramming are severely limited at
present. However, the progress in
simulation modeling made by mete-
orologists, especially at N (Na-
tional Center for Atmospheric Re-
search), is immediately useful, and
the interests of young oceanographers
and graduate students are highly com-
patible with such a program. Given
an environment amenable to interdis-
ciplinary research, computer facilities,
laboratory facilities, ship time, ac-
cess to aircraft, etc., the work could
be carried out with a good probability
of success. Provision for training of
students should, of course, be implicit
in any such effort, since the intel-
ligent use of any successful models
will depend on the availability of
qualified scientists of very high cal-
iber.
The highest priority should prob-
ably be given to the development of
ocean-wide models in view of the
potential dangers inherent in the
present situation, the virtual impos-
sibility of applying any positive cor-
rective action, and the long recovery
time implied by the nature of the
ocean circulation. However, the rap-
idly increasing rates of coastal and
estuarine pollution call for strong ef-
forts in modeling of these systems,
too.
235
PART VIII — AQUATIC ECOSYSTEMS
2. OCEANIC PRODUCTION
Primary Plant and Animal Life in the World Ocean
Aquatic Plants
In the sea as well as on land, the
primary producers of organic matter
are plants. It is estimated that
roughly 20 billion metric tons of
carbon is fixed by photosynthesis
in the sea each year. This amount
of carbon fixed annually should not
be confused with the total amount
of plants, in terms of carbon weight,
existing at any one time. Since the
process of organic production takes
place at a rapid rate in the sea, the
average standing crop of plants is a
small fraction of the annual produc-
tion. This makes a sharp contrast to
the plant production on land. The
total quantity of terrestrial plants
present at any one time is, on the
average, much greater than the an-
nual production.
Potential Use by Man — Another
striking difference between oceanic
plants and terrestrial plants is in
their size and distribution. The vast
majority of plants in the sea are
microscopic single-cell algae (see Fig-
ure VIII— 4) in contrast to the grass,
crops, shrubs, and trees that form the
bulk of terrestrial vegetation. These
small organisms, collectively called
phytoplankton, are diffused over vast
areas of the ocean. Even the great-
est concentrations of phytoplankton,
which occur in productive areas at
certain times, are nothing compared
with the density of plants in green
land areas. The enormous expense of
collecting these diffused, single-cell
organisms from sea water makes har-
vesting of marine plants for man's
use completely uneconomical. Fur-
thermore, many of the dominant spe-
cies of phytoplankton have hard
siliceous or calcareous skeletons that
make them unpalatable to man. For
these and many other reasons, the
use of phytoplankton as an important
source of food appears quite out of
the question.
There are various seaweeds and
other large aquatic plants, some of
which are used for food or for man-
ufacturing industrial products. Most
of them, however, are attached to the
bottom and therefore confined to
shallow inshore waters. The total
yield (in wet weight) of these plants
for all purposes from the world ocean
is about 900,000 metric tons a year,
or approximately 1.5 percent of the
total landings of marine fisheries.
More than half of this amount is
harvested in Japan. Harvesting of
large aquatic plants could be increased
greatly, but its contribution to the
supply of plant food as a whole
would be insignificant.
The Role of Phytoplankton — The
infeasibility of using phytoplankton
for food or other purposes does not,
of course, affect their basic role in
the economy of the sea. Animals can-
not manufacture living substance
from inorganic materials. They de-
rive it directly by grazing on plants
or indirectly by eating other animals
that have eaten plants. Thus, the
amount of carbon fixed by plants
(measured by 14C methods) is widely
used for evaluating the basic produc-
tive capacity of the sea. On a global
scale, it may be used for roughly
estimating the potential harvest of
the sea. Starting with the total fixa-
tion of organic carbon and using
various assumptions on the efficiency
of energy transfer, one can theoreti-
cally arrive at estimated harvestable
outputs at different levels of the
food chain. Estimates obtained by
this method vary widely, depending
on the assumptions used. Neverthe-
less, they indicate a general range
within which the potential harvest of
the sea should fall, as well as the
sources of inaccuracy inherent in
this method.
It has been demonstrated that,
among the areas where intensive ex-
ploitation of living resources has been
taking place, areas of high primary
productivities generally coincide with
those of high yields from fisheries.
Such primary productivity data by
area are useful in a variety of ways.
Used in combination with catch stat-
istics in heavily exploited areas, they
provide means to test the validity
of various assumptions on the effici-
ency of energy transfer, particularly
when data on secondary production
(i.e., zooplankton) are also available.
They also indicate some of the areas
that are grossly underexploited but
in which abundant potential re-
sources are likely to occur, as is the
case with certain parts of the Indian
Ocean, the tropical Pacific, and the
South Pacific. When such informa-
tion is combined with data on the
forms of animals likely to be abun-
dant in the respective areas, it will
provide a substantial scientific basis
for planning the exploration and ex-
ploitation of such areas in order to
extract greater amounts of animal
protein material from the sea. Also,
the differences in primary produc-
tivity between areas are such (1:50)
that there are many areas in the
world ocean that could be written
off, based on productivity data alone,
as potential fishing grounds for large-
scale industrial operations.
Numerous measurements of pri-
mary production have been made,
but they are largely in the limited
areas of the world ocean, and data
are quite scarce for most other parts.
It would be desirable to incorporate
primary production measurements in
236
OCEANIC i HON
Figure VIII— 4 — SOME PHYTOPLANKTON
(Copyright 1965, Houghton Mitflin Company, Boston, Mass)
The illustration shows drawings of some phytoplankton, enlarged about 400 times.
Diatoms:
10. Chaetoceros decipiens
11. Ditylium brightwellii
12. Guinardia flaccida
13. Eucampia zoodiacus
14. Thalassiothrix longissima
Dinoflagellates:
15. Peridinium depressum
16. Ceratium tripos
17. Ceratium furca
1.
2.
3.
4.
5.
6.
7.
8.
9.
Asterionella japonica
Rhizosolenia stolterfothii
Rhizosolenia alata
Grammatophora serpentina
Coscinodiscus excentricus
Biddulphia regia
Biddulphia sinenis
Lauderia borealis
Skeletonema costatum
as many oceanographic programs as
possible, with particular a\.l:,
paid to the usefulness of such data
as a basis for evaluating the relative
potentials of food production in dif-
ferent parts of the world ocean.
Zooplankton
Since most oceanic plants are ex-
tremely small, the typical forms of
marine herbivores are also very small
and planktonic, again making a sharp
contrast to grazing animals on land.
An enormous variety of small crus-
taceans and other invertebrates,
mixed with the young of larger an-
imals including fish, form a commu-
nity of herbivores and little carnivores
collectively called the zooplankton.
Although some species of larger an-
imals, such as bivalves, anchovies,
and sardines, also utilize phytoplank-
ton to varying degrees, the herbivores
of the zooplankton, particularly such
crustaceans as copepods and euphau-
sids, play an overwhelmingly im-
portant role in converting plant
material into animal material. The
size of planktonic herbivores in adult
stages ranges from less than one mil-
limeter to over five centimeters. They
have efficient filtering apparatus to
collect phytoplankton. Figure VIII— 5
illustrates some of the zooplankton.
Potential Use by Man — Aside
from their ecological role as the
main grazers in the sea, plankton
animals give some promise of being
harvested directly by man. Before
going into the detail of this aspect,
we must explain why man should
want to take the trouble of harvest-
ing these little animals. As organic
matter is transferred from plants to
herbivores, from herbivores to first-
stage carnivores, and from first-stage
carnivores to those of higher stages,
there are large losses of energy or
materials from respiration and de-
composition. The food web in the
sea is so complex that we have no
simple methods of estimating an
average loss at each stage of transfer.
For the sake of simplified discus-
sions, the efficiency of transfer from
237
PART VIII — AQUATIC ECOSYSTEMS
Figure VIII— 5 — SOME ZOOPLANKTON
(Copyright 1965. Houghton Miftlin Company, Boston. Mass!
The illustration shows drawings of some zooplankton, enlarged about five times.
Ostracods:
1. Gigantocypris mulleri: (a) adult with eggs, (b) and (c) two views of young
and more transparent specimen
2. Conchoecia ametra
3. Cypridina (Macrocypridina) castanea
Copepods:
4. Arietellus insignis, female
5. Gaetanus pileatus, female
6. Euchirella maxima, female
one trophic level to the next higher
level might be considered to be on
the order of 10 percent, the loss
being 90 percent. This means that
the total production (hence potential
yield) of zooplankton is much greater
than that of small fishes feeding on
zooplankton, and the latter in turn
far exceeds that of larger fishes prey-
ing on small fishes. Such small fishes
as anchovies, sardines, and herring
actually make up the bulk of the
world's total catch of fish. As the
exploitation of living ocean resources
becomes more and more intensive,
man will sooner or later look into
the possibility of utilizing small
planktonic animals, the abundance
of which is enormous.
On a very limited scale, zooplank-
ton has been used for many years
in some countries of Asia. In Japan,
for example, brackish or inshore
species of mysids (Anisomysis, Acan-
thomysis, and N eomysis) have been
used as materials for a traditional
food called "tsukudani" and also as
feeds for aquaculture. A deep-sea
pelagic species of sergestid shrimp
(Sergestes lucens), which grows to
40-50 millimeters, has long been
processed into dried shrimp. In
Southeast Asia (Malaysia, Thailand,
Indonesia, and Singapore), shrimp
paste manufactured from inshore
species of sergestid shrimps, mysids,
and other small crustaceans has been
a popular food consumed in substan-
tial quantities. The total amount of
zooplankton now utilized, however,
is negligible compared with the
amount available in any part of the
ocean.
For large-scale harvesting of zoo-
plankton, certain conditions would
have to be met. It would not be
economically feasible to harvest zoo-
plankton indiscriminately. Harvest-
ing must be done in areas where
dense concentrations of larger forms
of zooplankton occur, and special
plankton fisheries must be developed
for this purpose. Such concentrations
of larger forms are found in many
areas at certain times.
238
OCEA EDUCTION
The Antarctic Krill — There is
general agreement, among scientists,
that one of the most realistic targets
would be the exploitation of the
enormous resources of antarctic eu-
phausids (krills), particularly Eu-
phausia superba. The species occurs
only in the antarctic (i.e., south of
the Antarctic Convergence), and is
particularly abundant in waters off
South Georgia and around Antarc-
tica near the edge of the pack-ice.
Vertically, it occurs to a depth of
several hundred meters at larval
stages, but adults are often found in
dense concentrations in the surface
layer, forming patches of various
sizes and shapes. Sexual maturity is
reached in about two years, with an
average size of 50 millimeters.
The krill is the most important
food of whalebone whales migrating
into the antarctic in the summer; it
very often constitutes the entire
stomach contents of whalebone
whales caught there. Many other an-
imals, including seals, birds, and
fishes, also depend on the krill for
subsistence. (See Figure VIII— 6)
Although no reliable measurements
are available, the total annual pro-
duction of Euphausia superba might
be as much as one-half of the total
production at the level of herbivores.
Based on the estimated amount of the
krill eaten by whalebone whales in
the antarctic when the whale stocks
were large (they have been reduced
greatly by overexploitation), the po-
tential yield of Euphausia superba,
when fully exploited, might be as
high as 50 to 100 million metric tons,
or roughly equal to the present total
fishery yield from the entire world
ocean.
For some years, the Russians have
been conducting experiments in the
antarctic to develop methods of
catching and processing the krill.
They have used large surface trawls
and pumps to collect the krill, which
have then been processed into meal
or paste, and oil. The krill meal has
a reasonably high protein concentra-
Figure VII 1-6 — AN ANTARCTIC FOOD CHAIN
The diagram shows some of the major food chains found in the antarctic. Note
that the chain to the whalebone whales is relatively direct; the organic material
synthesized by the phytoplankton passes through only one intermediate animal,
the krill (Euphausia superba), before becoming transformed into whale flesh.
This direct change of plankton is extraordinary and a notable exception to the
normally low efficiency of the conversion of organic material from the sea.
239
PART VIII — AQUATIC ECOSYSTEMS
tion and the oil is rich in vitamins.
The high proportion of unusable
chitin (in the shell of the krill) and
the rapid spoilage rate present tech-
nological problems. But these prob-
lems will be solved sooner or later,
and the commercial exploitation of
the antarctic krill might become a
realistic proposition in the future.
The Japanese have also shown some
interest; research into the exploita-
tion of the krill is now part of their
national oceanographic program, al-
though they have not done very much
so far.
There are many other areas in
the world ocean where large concen-
trations of euphausids (of sizes
smaller than Euphausia sitperba) are
found, but the possibility of exploit-
ing them appears even more remote
than in the case of the antarctic
krill.
The California Red Crab — An-
other form of zooplankton that has
attracted much attention is the Cali-
fornia red crab, Pleuroncodes plan-
ipes. The animal has a pelagic
phase as well as a demersal (bottom-
living) phase. The relationships be-
tween the two are not well under-
stood, although the pelagic phase
appears to consist of relatively
younger individuals. It is possible
that the younger individuals can al-
ternate between the two phases.
In their pelagic phase, the crabs
are capable of grazing on phyto-
plankton, particularly larger diatoms.
They appear in vast surface con-
centrations in waters off Baja Cali-
fornia and become an important item
in the diet of a variety of predators —
birds, tunas, and whales, among
others. The red crab in the demersal
phase also occurs in dense concen-
trations.
Two species similar to the Cali-
fornia red crab are commercially
utilized in Chile, but their concen-
trations are found only on the bot-
tom. The exploitation of the Califor-
nia red crab for manufacturing meal
for animal feeds has been suggested
by many scientists. No experiments
have been conducted, however, to
test the commercial feasibility of
catching and processing the crabs
for this purpose.
In summary, the potential of zoo-
plankton as a source of animal pro-
tein material is great, and man will
go into this phase of exploitation of
living ocean resources sooner or later.
It is obvious that fisheries for zoo-
plankton would have to be developed
for specific forms of animals in
specific areas. However, even for the
species that appear most promising,
such as the antarctic krill or the
California red crab, much more work
is needed both in developing the
technology of catching and proc-
essing and in understanding the ecol-
ogy of the species involved, before
their commercial exploitation becomes
a reality.
The Southern Oceans in the Production of Protein
The antarctic oceans can be defined
for the purposes of this discussion
as the region between 60° and 65° S.
latitude in the three months of sum-
mer: January, February, and March.
Such an area subtends 3 million
nautical square miles of surface water.
During the other nine months of the
year, the weather and the extension
of sea-ice obliterate this area as ex-
ploitable for proteins by man. In-
clusion of sub-antarctic waters would
triple this area and extend its time
of usability at least two months
longer: December through April.
This discussion involves only ani-
mal proteins. There are no sources
of plant proteins, unless some may
be obtainable from the giant kelp
Macrocystis.
Protein Sources in the Antarctic
Historically, this 3 to 9 million
square nautical miles of surface water,
and the water-column under the sur-
face, have been rich in biomass of
animal proteins. The waters in sum-
mer have teemed with invertebrates,
particularly the relatively small pe-
lagic shrimp Euphausia and related
genera. There have been many nest-
ing birds, particularly on the sub-
antarctic islands. Seals have been
abundant from the ice-pack north to
the sub-antarctic islands and elephant-
seals on the sub-antarctic islands.
Whales have been, in the past, the
most conspicuous form of animal
life, and in their abundance have
supplied the whaling industry with
the bulk of its raw materials, mostly
oil, for fifty years, 1910-1960. The
supply of whales is practically gone
now, however. Fish have been found
sporadically in immense shoals, but
with such irregularity as to time and
place that no fishing industry has
grown up in antarctic and sub-
antarctic waters.
Species of Current Interest — With
the demise of the whaling industry —
which can return, but only after
many years, and which never utilized
the animal proteins to the fullest
extent — and with the end, in the
nineteenth century of the fur-seal-
ing and elephant-sealing industry —
which could have supplied proteins,
but never did, only fur or oil — atten-
tion is now being directed toward
harvesting euphausid shrimp and
240
PRODUCTION
fish. As yet, however, no one is able
to predict the success or failure of
attempts to exploit these supplies of
protein food in southern waters.
There have also been some explora-
tory harvests of shrimp-seals ("crab-
eater seal"), in order to obtain oil
and hides and, possibly, meat.
The dominant and incredibly abun-
dant species of euphausid is the two-
inch Euphausia superba, also known
as krill. This species often concen-
trates in such numbers that it colors
the surface reddish and washes up on
the decks of ships in heavy seas. It
should be possible to harvest great
quantities in slow hauls of tine-
meshed nets — but what to do with
them then?
The amount of shell in relation to
meat may prevent utilization for
human consumption, but the shrimp
could be ground into a meal for poul-
try. As the shell is "soft," such a
ground, dried meal might make a
highly satisfactory protein additive to
human food. The Soviets are the
only group to have made exploratory
harvests of Euphausia superba; what
success they had or what they did
with the shrimp is not clear.
Among other invertebrates, there
are considerable numbers of giant
barnacles, mussels, and stone-crabs
in sub-antarctic waters; harvest of
these can be increased if transpor-
tation to markets improves. None of
them is important, however.
Seals, particularly the ice-floe seal,
or shrimp-seal, Lobodon carcinophaga
and the elephant-seal Mirounga
leonina are potential protein foods
for animal consumption if the entire
carcass, except for hide and fat, is
ground and frozen in bags of 25 to
50 pounds. Such fresh meat-meal
would then include all meat, bones,
and entrails, and be nourishing as an
additive in poultry food, and as a
staple for fur-bearing animals.
Populations of the southern fur-
seals on sub-antarctic islands are
growing steadily, to the point where
limited harvest will be possible in a
few years without damage to the
stock. Here again, after hide and
fat are removed and utilized, the
entire carcass can be ground and
frozen in bags and used as fresh
meat-meal for poultry and fur ani-
mals. Such controlled exploitation
could also include the large southern
sea-lion Otaria byroni.
Exploitation by Man
The Norwegians have already con-
ducted postwar sealing in the ant-
arctic, principally on the shrimp-seal.
Fishing is under exploratory investi-
gation now by the United States, by
Germany in cooperation with Argen-
tina, and probably by the Japanese
and Russians. Also, some Chilean
fishing boats are now operating out
of Punta Arenas in the Strait of
Magellan.
The results of these investigations
seem to have been negative in large
yields per unit of effort. But mar-
ketable fish have appeared off South
Georgia Island in numbers in the
past, and these concentrations for-
merly gave a good yield to local
whalers fishing for their own needs.
More exploration might reveal some
pattern of availability by species,
locality, oceanographic conditions,
and season.
Whaling has been the only indus-
try in antarctic waters, indeed in the
entire antarctic area, land or sea,
except for the nineteenth-century
fur- and elephant-sealing, which was
conducted largely on sub-antarctic
islands.
Whaling started in 1904 at South
Georgia Island. From then until the
worldwide depression of the early
1930's it grew in volume and geo-
graphic coverage to a very high
point — too high, as was evident
even then, for maintenance of a suf-
ficient stock for continued high yield.
In the late 1930's, whaling again in-
creased greatly. It shui - Hiring
World War II, but increa
from 1946 to 1960, and it was
ous to most concerned people — all
except the whaling companies — that
the end was not far off. This end
almost came in the late 1960's, and
now the yield of whales is so low
that whaling is conducted by two
countries only, the U.S.S.R. and
Japan, who harvest mainly the sei-
whale, formerly an undesirable spe-
cies because of its relatively small size
(to 55 feet) and its relatively low
yield of oil and meat. Some finbacks
are taken, but the few remaining blue
and humpback whales are completely
protected.
There has been some effort by the
whaling industry in the past and
present, especially by Japan, to save
some of the proteins from whales,
either in the form of refrigerated
fresh meat, meat extract, or meat-
meal. But the main product has
been oil.
The prognosis for whaling in the
future is unclear. The industry may
continue on a low scale, but surely
it cannot grow as long as the popula-
tions of fin- and sei-whales are held
to low levels. Humpbacks may in-
crease to visible and perhaps harvest-
able numbers in five to ten years, but
whaling from shore stations in lower
latitudes on the winter-reproducing
herds — same stocks — may then be
undertaken.
Estimates of the time it will take
for the blue whale to recover run as
long as fifty years. All whaling
should cease for a while to allow even
the fin- and sei-whales to recover.
They could then yield a fair harvest
while the humpback and blue whales
also recover. And emphasis should
be on meat as well as oil.
Signs of Pollution — Contamina-
tion of the antarctic waters is not
now pronounced, although DDT has
been found in the fat of some pen-
guins and, perhaps, seals. The prog-
nosis for the future is not good,
241
PART VIII — AQUATIC ECOSYSTEMS
however, as is also the case with
water and land environments for the
entire world.
In summary, we have the following
potential sources of animal proteins
in antarctic and sub-antarctic waters:
1. Whales — large source origi-
nally, but much depleted by
impact of man.
2. Seals — some depleted by im-
pact of man, but others not;
uncertain source.
3. Fish — not depleted, but uncer-
tain as a source.
4. Euphausid shrimp — not de-
pleted, and perhaps more abun-
dant than before slaughter of
whales, but uncertain as a
source.
5. Other invertebrates — not de-
pleted, but uncertain as a
source.
Geographic considerations point to
utilization of animal proteins from
antarctic and sub-antarctic waters by
nations of the southern hemisphere —
Australia, Chile and Argentina, and
South Africa. Perhaps more of South
America and Africa can also benefit.
Hitherto, most of the oil and other
by-products from whales of antarctic
waters have gone to the mass of hu-
manity in the northern hemispheres.
But this need not continue.
Scientific Aspects of North Pacific Fisheries
The fisheries of the North Pacific
have expanded dramatically, particu-
larly in the past decade. This expan-
sion was the result of increased
utilization of the variety of living
resources available and exploitation
of new grounds (both in a geographic
and bathymetric sense). There has
been, particularly in the northeastern
Pacific, a dramatic increase in yields
as a result of Soviet and Japanese
fishing operations in the Bering Sea
and through the arc of the Gulf of
Alaska southward to central Cali-
fornia. Figure VIII— 7 shows a map of
the world's fisheries.
The growth pattern of fisheries in
this area, as with many areas of the
world, has changed during the past
fifteen years. Fisheries may grow
to maturity, exceed the productive
capacity of the stocks, and collapse
in a matter of a few years. Hence,
man's utilization of the ocean's bio-
logical potential suffers from an in-
ability to cope with "pulse-type"
fishing activities, lack of an effective
organizational structure to implement
management systems, and a rather
shabby concept of the impact that
selective fishing may have on the re-
source community. In addition, po-
tential interaction of fisheries with
other demands on the ocean and its
seabed (mineral exploitation, petro-
leum, etc.) is not predictable.
In summary, the existing prob-
lems as they relate to North Pacific
fisheries are: (a) how to optimize
yields or dollars from what we are
now using; (b) how to minimize
multiple-use conflicts; (c) how to
maintain the productivity of the sys-
tem (avoiding degradation and prod-
uct contamination); and (d) how to
extract the rather extensive under-
utilized biological material that in-
habits this part of the ocean.
Status of Scientific Knowledge
Data Base — There is now a fair
body of scientific information charac-
terizing the fish and shellfish in the
North Pacific Ocean. We have a rela-
tively good understanding of the geo-
graphic and bathymetric distribution
patterns of the demersal forms, and
we are beginning to have a fairly
good grasp of the general magnitude
of these resources. The North Pacific
pelagic overshelf species are also rela-
tively well known, as are their dis-
tribution and behavior features. Our
understanding of the distribution fea-
tures and magnitude of the pelagic
oceanic species is far less good.
Knowledge of the types, distribution,
and abundance of benthic inverte-
brates, although far from perfect, is
probably adequate to get some gross
concept of their potential contribu-
tion as food for man. By contrast,
our knowledge of pelagic inverte-
brates, even in the shallower waters,
is quite poor; and we have only a
rudimentary understanding of the
community, their distribution, abun-
dance, and the quantities that might
be available as a food supply for
mankind.
We have fair information on sea-
sonal and bathymetric migratory pat-
terns for two dozen or more species
of fishes in the northeastern Pacific,
and perhaps no better in the western
Pacific. However, from these data we
cannot formulate a general model of
the seasonal distribution patterns of
biological matter. The specifics of
such movement and migration on
many species are absent. Our knowl-
edge of the factors that influence
behavior and gross distributional pat-
terns of adults is also rudimentary,
and we know even less concerning
hydrological parameters that are criti-
cal in determining survival of the
young.
The underlying processes for de-
termining year-class strength, cyclic
242
OCEANIC PRODUCTION
Figure VII 1—7 — DISTRIBUTION OF THE WORLD'S FISHERIES
INDIAN
OCEAN
^] COASTAL AREAS— About 50% ol Global Commercial Harvest
s.^> UPWELLING AREAS— About 50% ot Global Commercial Harvest
_| Less than 1% of Global Commercial Harvest
INDIAN
OCEAN
The map shows the fisheries of the world today. Fish production in the future
will depend on the responses of this system to exploitation and on the oppor-
tunities that may derive from a better understanding of the system. One critical
factor is the total fish production of the oceans, which has recently been estimated
to be only four times greater than the 1968 catch, for corresponding species.
Another is the vital role played in estuaries and along coastlines, where pollution
threatens the nurseries of many commercial species. A third is the role of
upwelling. Weather is important to the success of fishing, and further improve-
ments in local weather forecasting await a better understanding of larger-scale
meteorological phenomena. Altogether, the systems of air, water, and life are
intimately interwoven in the production of fishery yields.
dominance, and succession in the
ocean communities are the subject of
considerable rhetoric, most of which
is rather fanciful. Hence, we have
not been able to get a firm grasp of
the relationship between parental
stock and subsequent recruitment,
nor have we been able to interpret
the implications of environmental
contamination (degradation) on early
life-history phases of marine fauna.
Knowledge of the environment that
various groups of commercially ex-
ploited fish and shellfish inhabit has
improved considerably in the past
decade, although it is descriptive in
character. We can probably state
that we now have a fairly firm esti-
mate of mortality coefficients (mor-
tality, growth rates, etc.) for repre-
sentative species that are subject to
commercial fishing. It is possible that
we can generalize and make fairly
good estimates for species for which
these coefficients have not been estab-
lished. Similarly, we are starting to
get a fix on the response of single-
species fisheries to the mortality re-
sulting from man's exploitation.
Limitations — By contrast, how-
ever, the existing models are inade-
quate to cope with multi-species or
243
PART VIII — AQUATIC ECOSYSTEMS
community exploitation. The concept
of optimizing yields from single
species, although argumentative, is
established in principle. But models
are not yet available on which to base
an aggregate species-management ra-
tionale, and we haven't the foggiest
idea of the possibilities of exploiting
marine fishes on a range-management
concept. Finally, although there is a
good body of information relating to
feeding patterns of fish, the tropho-
dynamics, or energetics, of food-chain
systems are still poorly understood
and are, to a degree, rooted in
mythology.
Recent Additions to Scientific
Knowledge — Considerable new in-
formation on the distribution, mag-
nitudes, and community aspects of
demersal and benthic fishery re-
sources has been compiled, particu-
larly during the past decade for cer-
tain areas of the North Pacific.
Important among these are the
recent Soviet works (four volumes)
which provide life-history data and
information on the dynamic aspects
of the fish and shellfish resources of
the Bering Sea and Gulf of Alaska.
These volumes also include new con-
tributions as related to benthic com-
munities, some new descriptive ocean-
ography, and an attempt to establish
environmental-resource relationships.
In addition, the recent contribution to
the understanding of the Kuroshio
Current should provide a basis on
which to examine its influence on the
adjacent fishery resources.
The contribution of oceanography
to fisheries in the past decade lies
largely in describing the environment.
This contribution must be tempered,
however, by the fact that the de-
scriptive features to date are too gross
to deal effectively with some prob-
lems, particularly those relating to
survival of eggs, larvae, and young
of species that are commercially
utilized. Furthermore, the availability
of theoretical formulation, including
mathematical modeling, exceeds our
empirical capacity to evaluate model-
ing forecasts.
Needed Scientific Advances
The major scientific controversies
concerning the North Pacific fisheries
relate to (a) the total possible contri-
butions of its elements to the food
stream, (b) the importance of mari-
culture vis-a-vis developing more effi-
cient systems to utilize wild stocks,
and (c) the character of relation-
ships between adult populations and
recruitment.
Fisheries Management — Among
the priorities for scientific advance is
the need to develop management
concepts and techniques for timely
implementation of management. Fish-
eries management has been and con-
tinues to be largely remedial in
character. We need to cope with the
problem of pulse-fishing activities,
examine it as a theoretical basis for
utilizing ocean resources, and find
mechanisms that will allow us to
forecast trends sufficiently in advance
of their manifestation to implement
effective management. The concept
must cope with managing aggregates
as well as single species.
The most critical scientific needs
as regards management and use of
North Pacific fisheries relate to de-
riving the nature of the stock recruit-
ment relationship, the reaction of
multi-species fisheries, the prediction
of environmental factors that bring
about year-class fluctuations or other-
wise influence stock recruitment rela-
tionships, and a clear, fundamental
understanding of the potential impact
of persistent pesticides and other for-
eign substances on the productivity
of the total ocean food chain, as well
as the potential contamination of the
food sources.
A number of fishery resources in
the North Pacific appear to have
been overexploited, resulting in loss
of food potentials. This seems to
have been the product of failure to
find an effective means of implement-
ing management decisions and the
inability of existing monitoring sys-
tems to detect important changes in
sufficient time to react in a respon-
sive manner.
Resource Assessment — In addi-
tion to the problems of managing
exploited resources, there is a real
need to evolve the fishing strategy
that will allow us to use the full
potential in the ocean. This may re-
quire considerable information on the
behavior patterns of species (a) in the
natural state, (b) in response to exist-
ing fishing gears, and (c) in response
to physical or chemical stimuli that
might be used for herding or aggre-
gating marine life.
One of the shortcomings is tech-
nological instrumentation to carry out
resource-assessment activities. Most
of the classical methods are not really
effective for the task. One of the real
weaknesses of the data is that they
do not provide contemporary infor-
mation. The greatest success is likely
to come from the development of
sonar assessment techniques. Inte-
gration of returned echoes, in con-
junction with a means of identifying
the target, could provide a reliable
method for obtaining stock data over
wide areas within reasonable costs.
Acoustic holography offers some
promise of fish identification detected
at relatively close ranges.
Impact of Pollution — Perhaps the
greatest urgency relates to the area
of the multiple demands on the
ocean's environment. The hazards of
pollution in the North Pacific and the
potential contamination of the food
resources therein are major questions
that must be answered in the next
decade. We are only beginning to
consider the possible implication of
man's multi-purpose needs on the
ocean's environment. The whole field
of pollution — ranging from persist-
ent pesticides and other industrial
chemicals to oil pollution and the
like — obviously represents a danger
which is not adequately understood.
244
PRODUCTION
These dangers must include potential
alteration of the environment as the
result of the heat added as a by-
product of generating electricity by
nuclear means. The whole concept
of the ocean's capacity to produce
food for man and the technological
capacity to use it is a subject of cur-
rent discussion. The impact of loss
of these resources or inability to de-
velop their potential must be consid-
ered in evaluating future food sources.
We cannot assume that pollution
problems will be resolved in time to
maintain present biological produc-
tion. Indeed, man's multi-purpose
needs to use the water environment
for transport, to exploit its mineral
potential, to develop it for real estate
and industrial pur] to use
it to dispense his waste products in-
crease the likelihood that we may
ultimately degrade the general pro-
ductivity of the sea. In this respect,
the criterion of sublethal level of tol-
erance is irrelevant if the accretion
of pollutants continues. Time, in this
instance, does not possess the infinite
quality usually ascribed to it.
Some Scientific Problems Associated With Aquatic Mammals
The following list of problems as-
sociated with aquatic mammals is
made up mostly of broad, general
problems. There are also many spe-
cialized problems, such as diving
physiology or the ecology of specific
parasites.
Pollution Hazards
Effect of Pesticides, Petroleum, and
Other Pollutants on Marine Mam-
mals — The flow of pesticides and
other chemical pollutants into the
ocean is concentrated in marine mam-
mals since they are at the top of the
food chain. (See Figure VIII— 8) It is
known that chlorinated hydrocarbons
are in the tissues of marine mammals
in every part of the world. The effect
of the chemicals is not at all known.
A possibility exists that the apparent
high rate of premature births in Cali-
fornia sea-lions is related to pollutants.
Little is known about the effect of
petroleum on marine mammals except
that it reduces the insulating capa-
bility of fur. This is lethal for sea
otters and fur seals in the marine
environment and for the furred fresh-
water mammals such as otter, mink,
muskrat, and beaver.
Pollution of the types mentioned is
continually increasing. Unless the
hazards are understood, marine mam-
mal populations can be reduced or
lost before the potential effects of the
hazard are realized. A variety of
sampling experiments and tests with
captive animals can be devised to
show the effects of the pollutants.
Conservation and Management
of Stocks
Management of World Whale
Stocks to Preserve the Species and
Restore a Resource — Short-term eco-
nomic gain has been the overriding
consideration in the exploitation of
the large species of whales. Pursuit
of this end has resulted in depletion
Figure VIII— 8 — THE FATE AND DISTRIBUTION OF MARINE POLLUTANTS
POLLUTANT
Diluted and
dispersed by
MARINE
ENVIRONMENT
Turbulent
mixing
Ocean
currents
Uptake by
fish
Transported
by
Ocean
currents
Migrating
organisms
Concentrated
by
Biological
processes
Chemical and
physical processes
Uptake by
phytoplankton
Uptake by
seaweeds
Adsorption
Precipitation
Invertebrate
benthos
Zooplankton
z
Fish and mammals
Ion
exchange
Accumulation
on the bottom
The diagram shows the various processes that determine the fate and distribution
of pollutants in the marine environment. Under favorable conditions, the pollutants
are diluted, dispersed, and transported by turbulent mixing, ocean currents, and
migrating organisms. Unfortunately, the oceans are not mixed thoroughly and
high concentrations of pollutants exist in local areas. In addition, there are
biological, chemical, and physical processes taking place that concentrate
pollutants and lead the pollution back to man.
245
PART VIII — AQUATIC ECOSYSTEMS
of all of the large whales with the
possible exception of sperm whales.
Sufficient biological and statistical
knowledge is now available to put a
rational management system into ef-
fect. In part, this may have been
done. Continued studies are needed,
however, to make certain that the
quotas already in effect can be sup-
ported by the whale stocks (to date,
populations of large whales have been
measured principally by catch effort)
and to help in the establishment of
new quotas and regulations. This will
require a combination of biological,
statistical, and diplomatic effort.
International Study and Conserva-
tion Agreements on the Ice-Seals of
the Bering and Chukchi Seas — The
expansion of commercial killing of
ice-seals (ribbon-, bearded-, and
harbor-seals — ringed-seals are little
hunted) by the Soviet Union has
resulted in depletion of the ribbon-
seal population and has put an added
strain on the subsistence living of the
Alaska Eskimo. There is a need,
agreed to in principle by the United
States and the U.S.S.R., for rational
harvesting of the ice-seals, arranged
by an international agreement. Co-
operation between countries increases
the effectiveness of data collecting
and reduces the effort required of
each party.
The knowledge needed to manage
ice-seal populations is difficult to col-
lect. Harvest quotas set on a trial-
and-error basis may be used tem-
porarily until more data are available.
An International Policy on Exploit-
ing the Seals of the Antarctic —
World whaling and the harp-seal
hunting in the North Atlantic yield
less and less. As a result, nations
such as the U.S.S.R. and Norway
have begun to look at the seals of
Antarctica as a source of leather and
oil. An international policy covering
quotas that can be killed, by species
and area, is still incompletely formu-
lated. Some effort has been devoted
toward developing an international
plan. This work should be continued
even though the basic data for quotas
is difficult to assemble and provisional
quotas will need to be established at
first.
The main protection for antarctic
seals is the hostile environment. An
opportunity thus exists to exploit
marine mammal populations in a
rational way.
The Conservation of Dolphins that
are Killed in the Yellow-Fin Tuna In-
dustry — The fishermen catching yel-
low-fin tuna off Central America with
purse seines use schools of dolphins
as indicators of tuna. The tuna, for
unknown reasons, are under the por-
poise schools and follow along with
them. The purse seine is set around
the dolphins and catches both dol-
phins and tuna. (See Figure VIII— 9)
Observers estimate that five dolphins
are killed for each ton of tuna caught.
Fishermen would like to release the
dolphins to use again in finding tuna
but no effective way of releasing
them has been devised. A solution to
the problem will require further study
of dolphin behavior and experiments
in net design.
Factors Affecting Distribution
Mechanisms Used by Marine Mam-
mals to Guide Migration — Some
marine mammals make extensive an-
nual migrations. A variety of specu-
lative suggestions have been made on
how the mammals are able to navi-
gate regardless of weather conditions
and daylight or darkness. In fact,
however, little is known about the
mechanisms used to guide migration.
The process appears to be more so-
phisticated than some of the theories
might suggest. Discovery of these
mechanisms would be of great bio-
logical significance and also important
in human navigation and communi-
cation.
The methods of investigation that
will explain how accurate navigation
over thousands of miles is accom-
plished are not well worked out. A
combination of approaches will prob-
ably be necessary.
Relation of Oceanographic Con-
ditions to the Distribution of
Figure VIII— 9 — A PURSE SEINE
Cork Line
Lead Line
Purse Line
Purse Ring & Bridle
E Purse Weight Line
F Purse Weight Block
G Pursing Blocks
H Purse Weight or Tom
The sketch shows a purse seine being set. The net is placed in the water. The
upper edge is kept afloat with buoys, while the lower edge sinks due to weight.
The net is drawn around a large volume of water. It is possible to close off the
bottom by pulling the net together, thus enclosing any fish within the volume. The
entire seine — and all its contents — can then be picked out of the water.
246
OCEANIC PRODUCTION
Marine Mammals — Oceanographic strated. Analysis of the accumulating population studies on mammals such
conditions apparently have a strong data on ocean conditions can give as the northern fur seal that spends
influence on the survival of marine a much better understanding of the many months at sea. Reasons for the
mammals, particularly during their ecology of marine mammals than now great variation in survival of year
first year. However, satisfactory cor- exists. Unless this can be done an classes cannot be found in the land
relations have not yet been demon- impasse may have been reached in environment.
247
PART VIII — AQUATIC ECOSYSTEMS
3. ESTUARIES AND COASTAL ZONES
The Relationship of Fisheries to Estuaries,
With Special Reference to Puget Sound
The total estuarine system of Puget
Sound has historically provided food,
recreation, and great aesthetic value
to increasing numbers of people.
Other major uses include shipping
and waste disposal. Potential uses
may involve oil exploration and drill-
ing, utilization of other under-water
nonrenewable resources, provision of
more land and living space by modifi-
cation of shallow water areas, and, of
course, a great increase in food pro-
duction through development of vari-
ous types of aquaculture or even
through enlightened manipulation and
control of the larger man-made vari-
ables. It is the purpose of the follow-
ing statement to point out the neces-
sity for identifying existing and
future goals and problems related to
the fisheries of Puget Sound.
There is at present no scientific
basis for deciding how to optimize the
fisheries of Puget Sound while giving,
at the same time, full attention to the
other existing and potential uses of
the estuary. Interaction among the
multiple uses of Puget Sound can be
expected to be either detrimental or
beneficial to the fisheries, but as yet
the places and extent of interaction
are poorly known, the future signifi-
cance of interaction is unpredictable,
and therefore the opportunities for
planned control are severely limited.
Types of Information Needed
To achieve a scientific basis for
action there must first be an accept-
able definition of the goal or goals
being sought. That is, what benefits
does man expect to realize from an
estuarine system: food, recreation,
tourism, industry, . . . ? For the pur-
pose of this statement it is presumed
that viable sport and commercial
fisheries (both fish and shellfish) are
accepted goals and that they are so
strongly desired that any factor which
significantly affects them should be
identified as fully as possible.
Biological — The species of fish
comprising the commercial and sport
fisheries of Puget Sound are well
known, and relatively good catch
statistics are available for most of
them. We have developed, and are
continuing to develop, the capabilities
to observe and record changes in
fishery populations. Relationships be-
tween various species of fish popula-
tions, their environment, and the
ultimate causes of change, however,'
are not well understood at present.
For example, what effect does exploi-
tation at one trophic level (e.g., her-
ring) have on the abundance of fish
at a higher level (e.g., salmon)? Pre-
dictions of changes in fish popula-
tions are still in their infancy and in
most cases will remain so until these
causes for change are better under-
stood. Important questions need an-
swers in this area. For example, how
does progress in serving industrial
and residential development needs af-
fect the nursery areas and food-chain
organisms that support the desired
fish and shellfish species intended for
commercial and recreational harvest?
Environmental — These are the en-
vironmental problems currently af-
fecting the fish and shellfish species
and their fisheries in Puget Sound:
1. Physical degradation.
(a) Marinas, breakwaters,
docks, landfills (residential
and industrial), log boom-
ing, and sawmills.
(b) Dredging, rechannelling of
river mouths and estuarine
areas.
(c) Altered river discharge pat-
terns due to man's activities.
(d) Thermal power sites.
1) Heat discharge.
2) Screening of intake.
3) Use of biocides.
4) Radioactive uptake in
food chain.
(e) Litter pollution (disposal of
garbage and other solid
waste).
(f) Bio-fouling (which has
sometimes made gill nets in
Puget Sound totally ineffec-
tive).
2. Organic and inorganic degrada-
tion.
(a) Pulp-mill discharge.
(b) Sewage discharge (including
detergents and other house-
hold wastes).
(c) Chemical pollutants (alu-
minum refineries, smelters,
metal-plating).
(d) Petroleum-product pollution
(oil refineries and petro-
chemical plants).
(e) Toxicants from plastics
manufacturing.
(f) Agricultural wastes; organic
and inorganic fertilizers.
(g) Siltation and debris from
logging activities.
248
ESTUARIES AND COASTAL ZONES
3. Possibilities for beneficial ef-
fects from man's activities.
(a) Planned addition and dis-
persion of nutrients.
(b) Selective warming by use
of water discharged from
power plants.
(c) Control of unwanted species
by manipulation of appro-
priate variables.
Political, Social, and Economic —
How are diverse value measurements
equated for the several benefits that
may be derived from an estuary?
What is the biological value of clean
water? The aesthetic value? What is
the value of a recreational fishery?
Gaps in Existing Knowledge
If the fisheries constitute only one
of the values to be realized from an
estuary, then satisfactory manage-
ment of the entire system cannot
be achieved unless there is a means
of judging the other values and of
expressing the possible interactions
to be expected as the renewable and
nonrenewable resources are har-
vested. Relative values cannot be
judged unless there is comprehensive
knowledge available about the es-
tuary.
Descriptive Information — There is
an immediate need for more descrip-
tive information about Puget Sound.
Patterns of water circulation need
particular study, including the amount
of fresh water in the system, amount
and location of runoff, tides, winds,
and density differences. Such infor-
mation will be indispensable if the
fisheries are to be protected from
planned and unplanned disposal of
waste in Puget Sound. It is entirely
possible that the judicious addition
of nutrients from domestic and agri-
cultural sources might be accom-
plished in a manner to enhance the
productivity of the fisheries. The
extent of nonrenewable resources (oil,
sand, aggregate) within Puget Sound
should be more fully known. Di-
rectly or indirectly, their extraction
could have a significant effect on
the fisheries.
Baseline Studies — To fill another
large gap in existing knowledge of
Puget Sound, comprehensive baseline
studies of present conditions — chemi-
cal, physical, and biological — are
needed. Man-caused changes can
hardly be evaluated unless a norm
is known against which the devia-
tions may be judged. Time-series
studies of physical and chemical fac-
tors are required, as well as deter-
mination of the amounts and kinds
of organisms and appropriate infor-
mation on their condition. These
basic studies would necessarily deal
with each phase of an organism's
life cycle in order to uncover, for
particular species (e.g., English sole),
the requirements while on the spawn-
ing grounds, in the planktonic phase,
in nursery areas, and as a growing
juvenile and adult. It is also vital to
learn how much deviation in habitat
conditions a fish or shellfish can
tolerate and to know the optimum
preferred level of each important en-
vironmental parameter. The lower
trophic levels would also require de-
tailed attention, inasmuch as they are
indispensable to the continued har-
vest of fish and shellfish.
Economic Values — Until better
economic measures are developed for
evaluating the fishery resource, fish
and shellfish species more frequently
than not will continue to receive
relatively low priority when com-
pared to other competitive and detri-
mental uses of the Puget Sound es-
tuary. Figure VIII— 10 presents data
for a similar situation in Corpus
Christi Bay.
Modeling Studies — After suitable
data are at hand, a modeling study
should be conducted. By this means
the organic-matter budget of Puget
Sound could be simulated. The prob-
able role of organisms as indicators
of a changing environment could be
studied. Furthermore, a theoretical
treatment could be expected to aid in
establishing an effective long-term
sampling plan and in implementing
a reasonably good predictive ability
concerning changes in fish popula-
tions. Economic values and socio-
political considerations must also be
used in such a model if all areas of
consideration for decisionmakers are
to be included.
Figure VII 1—1 0 — VALUE OF ECONOMIC ACTIVITIES IN CORPUS CHRIST! BAY
Economic activity
Dollars
per acre per year
Biological-aesthetic uses
Tourist and local resident expenditure
Commercial fishing
152
15
Total biological-aesthetic uses
167
Industrial uses
Oil, gas, and shell
Cooling water
Transportation savings in shipping
Effluent disposal savings
130
10
64
1
Total industrial uses
205
Total dollar yield
372
The chart gives an estimate of the dollar value of major activities in Corpus
Christi Bay during 1958. No one user was predominant, so no claim could be
made for predominant right to use of the bay on economic grounds. Note the
small dollar value of commercial fishing and the large value of aesthetic and
mining uses.
249
PART VIII — AQUATIC ECOSYSTEMS
Acquisition of Needed Information
Existing federal, state, and private
agencies are fully capable of gather-
ing and interpreting all the technical
data that may be pertinent to an
understanding of fisheries problems
as related to the estuarine features
of Puget Sound. The accumulation
of certain types of basic data can
proceed at once; for example, water
circulation, life history and ecological
studies of selected fish and shellfish,
and tolerance of estuarine organisms
(including ones at any level of the
food chain) to induced environmental
changes. But the full range of needed
information cannot be anticipated un-
til at least a broad definition of the
desired goals has been achieved. Pub-
lic participation in the selection of
goals that are practical for the present
and future management of the Puget
Sound estuary will necessitate clarifi-
cation of the alternative uses of the
estuary that are available and their
resulting effect on the commercial
and recreational fisheries in Puget
Sound. Identification of alternative
uses of the Puget Sound estuary be-
comes, therefore, an immediate and
pressing need.
Once the needed information for
achieving desired goals is at hand, the
implementation of recommended ac-
tions might well involve federal, state,
local, private, and industrial groups.
Communication between the involved
agencies and groups is indispensable.
Concerted action or unified jurisdic-
tional authority must be established
in order to assure appropriate execu-
tion of an adopted plan. A variety
of formal and informal schemes are
presently used to achieve at least
partial coordination between agencies
with overlapping authority and re-
sponsibilities relating to Puget Sound.
A mechanism to guarantee consulta-
tion between agencies is needed, as
well as a method to provide for reg-
ulatory actions that are consistent
with respect to accepted objectives.
Prospects for Aquaculture
As a result of the rapid increase
of interest in aquaculture, aquatic
biologists and fishery biologists who
are familiar with the inshore areas
of the oceans have been besieged
with questions from industrialists.
These questions most often concern
the costs of farming and the profit
to be realized.
Major Considerations
There are no simple answers, for
the factors involved are more com-
plex than they might at first appear
to be. A fishery biologist would need
to possess the knowledge and skills
of a variety of specialists to provide
adequate answers. For instance, fish-
ery biologists are rarely marketing
specialists. They have traditionally
been trained to manage populations
of fish and shellfish from the stand-
point of providing a maximum sus-
tainable yield in terms of numbers of
fish or weight of fish from a partic-
ular exploited stock. Only in recent
years have fishery economists pointed
out that a vital aspect of managing
fisheries is the economic yield. Con-
sidering costs to harvest and market
value, fishery economists ask at what
level of fishing can the maximum
economic yield to the fishery be
realized.
To minimize costs it is often nec-
essary to limit fishing effort, since
harvesting is carried out by inefficient
means because of restrictions on ef-
ficient gear or requirements of more
vessels and men than are needed to
harvest the crop. Information neces-
sary to determine the optimum eco-
nomic level of harvesting stocks from
many fisheries is still unavailable.
The biologist is generally ill-pre-
pared to present the type of infor-
mation that industry is requesting
for aquaculture. Unfortunately, the
answer is very complicated, involving
a host of variables.
Species Selection — There are ques-
tions the biologist is well qualified
to answer, however, such as the feas-
ibility of farming a certain few spe-
cies. If he is asked about shrimp,
for example, he can point out the
extent of the available biological
knowledge on this species and where
difficulties may arise that will be
costly to the investors. If asked about
other species (for example, spiny lob-
ster or the common pompano), he
must reply that no one has reared
these animals from eggs to adults and
that a lot of basic research must be
done before that species will be suit-
able for farming from a biological
standpoint, which is, in turn, many
steps and years away from farming at
any economically profitable level.
Suppose, for example, that larval life
of the spiny lobster turns out to last
five or six months; then the cost of
rearing the lobster through these
stages can be so high as to be un-
profitable.
Furthermore, biological research,
like everything else today, is ex-
tremely expensive. To obtain what
might seem to be answers to simple,
straightforward biological questions
can be very costly, and even then
the answers obtained may pertain
only to a certain set of conditions
tested in the experiments; under an-
other set of circumstances, the biol-
ogist might find quite different results
from his research.
Location — In addition to the selec-
tion of a farmable species, potential
250
ESTUARIES ANT AL ZONES
profit also depends upon the choice
of a suitable geographic area. It is
becoming increasingly difficult to find
large estuarine areas and water sup-
plies that are unpolluted and that
provide the necessary requirements
for aquaculture. Any hope of estu-
arine sea farming in many areas,
especially those close to large cities,
must be abandoned immediately be-
cause suitable areas cannot be found,
or, if they are available, are priced
prohibitively. Areas away from large
cities offer greater hope for aquacul-
ture, but the cost of just the land
investment can be substantial, espe-
cially in sea farming.
Feed — Aside from finding suitable
locations, a number of other impor-
tant aspects can greatly affect fish-
farm production and, hence, profits.
Feeding, of course, is high on the
list. What feeds are required for the
farmed species as young and adults
is important in the profit equation.
Do these feeds provide rapid growth
and high survival? Research into
nutrition requirements has resulted in
foods designed specially for trout and
channel catfish in freshwater. But for
many of the animals considered for
sea farming, biologists are unsure of
what foods they consume in nature,
let alone what is the most desirable
food for these species in captivity.
This important quantity in the for-
mula must be solved before costs
and potential profit from mariculture
can be estimated.
Manpower and Technology —
What sort of personnel are available
to operate a sea farm in a particular
area bears on the potential profit.
Some species require only rather
menial tasks; others require skilled
personnel or trainable persons. For
example, mass rearing of microor-
ganisms is a necessity. Again, until
answers to these questions can be
provided, the amount of profit pos-
sible is only speculation. In many
areas of aquaculture today technology
is moving rapidly, thereby making
speculation based on today's tech-
niques of little value tomorrow.
Market Information — Many re-
ports in the past five years or so
have produced abundant information
on how many fish can be obtained
from a certain amount of water in a
particular time period. There is little
freshwater farming and even less
sea farming in the United States at
the present time; therefore these fig-
ures have been obtained in other
areas of the world. Since they give
some guidelines as to productivity
they are valuable in themselves, but
they must be examined carefully.
What sort of market exists for the
species? In some areas of the world
very small fish are an important mar-
ket item. In the United States this is
not the case. Also, we might ask
whether this high production is the
result of some unusually fortunate
combination of circumstances? For
example, when we consider the ex-
tremely high production of rafted
mussels in the Bay of Vigo (Spain),
where three-dimensional water use
is practiced, we find that plankton is
unusually rich. In some areas of
Asia where human and farm sewage
is used as fertilizer, production is
extraordinary. At this time, in many
of the developed countries, there
would seem to be little hope of using
fertilizers of this kind. It should be
added that the time is probably ap-
proaching when we will have to util-
ize these wastes fully, but in a more
sophisticated way, and fish farms
are one logical place for doing so.
The entire present and potential
market for any particular species
must be examined with care before
the question of potential profit can
be answered. This is obviously within
the expertise of the market special-
ists, not the biologists. The species
considered now in the developed
countries are those with high market
demand and high price. However, if
the species can be raised in large
quantities, this picture can be altered
greatly: they can become a popular
consumer item and be available to
a larger segment of the consumer
population. Also, a number of other
species are profitable to raise, but a
lot of money would have to be
on market promotion before the
housewife would consider purchas-
ing them.
Conservation Laws — The status of
conservation laws can greatly affect
profit from aquaculture. These must
be relaxed to give the farmer com-
plete freedom to market any size of
fish any time of the year. Put another
way, the farmer must not have to
try to fit his operation into a scheme
of laws supposedly designed to con-
serve stocks of wild fish. Two sets
of laws concerning the same species
should be in effect — one for the
fishermen and one for the farmers.
Conservation groups place restric-
tions on certain times of the year
for extended periods. It is during
these times that a substantial profit
can be realized by sea farmers, who
can control their production so that
they can harvest at times of peak
demand. This is common procedure
in the Philippines, where milkfish are
harvested during the monsoon season
when fishermen cannot fish. In Ja-
pan, Fuginaga takes advantage of the
great demand for live shrimp during
their holiday season in order to ob-
tain a premium price for his product.
Technology — There are many
other important considerations which
prevent anyone trained in a particular
discipline from being in a position
to provide answers to questions con-
cerning costs and profits in fish farm-
ing. Engineering aspects of building
ponds, sealing, and providing the
necessary water flow are important
facts needed for profitable aquacul-
ture. Some corporation research and
development personnel are visiting
biologists as a means of keeping up
on the trends in research and the
feasibility of profitable aquaculture.
They find that there is only a little
commercial fish farming in the United
States and that those operations that
do exist are on a small scale. Even
without the very formidable road-
block of the reluctance of private
business to disclose costs and profits
to would-be competitors, there is no
251
PART VIII — AQUATIC ECOSYSTEMS
long history of aquaculture in this
country to permit estimates of aver-
age cost or average profit.
Current Research Activity
The larger, more progressive cor-
porations are doing more than asking
questions of the biologists. They are
paying for research on the biological
and marketing aspects of aquaculture
in order to judge whether their cor-
porations should enter into these
ventures.
Despite the lack of economic data
to justify large-scale aquaculture in
developed countries, many facts and
principles gained from biological re-
search and from common sense serve
as guidelines for anyone interested
in fish farming. The developed coun-
tries have the technology to farm
their waters efficiently, but they lack
the decades of experience that is
available in Asia, for example. Aqua-
culture in the developed countries
must be a profit-making venture, and
since markets for many of the species
suggested for this are already present,
or can be developed with little pro-
motion, it would seem that it could
indeed be profitable. In the devel-
oped countries, too, there has been
a boom in oceanic research. A con-
siderable share of the results of this
scientific research is applicable to
mariculture. It is quite obvious that
the greatest potential exists for those
species that feed low on the food
chain, such as some of the crusta-
ceans and mollusks. Figure VIII— 11
shows one such scheme.
Biologists who are trying to eval-
uate the status and near future po-
tential of aquaculture recognize that
its maximum effort will be in the
near shore waters where there is sub-
stantial evidence of extremely high
fertility. Of course, the matter of
ownership and operating costs be-
comes more complicated and costly
as the distance from shore increases.
In at least one United States oyster-
farming operation, radar has been
used to detect trespassers into leased
or owned bottoms who may be help-
ing themselves to the ingredients for
a stew, from private stock. In Spain,
Japan, and the State of Washington,
scientists and sea farmers have clearly
demonstrated that high oyster pro-
duction is possible by using hanging
cultures, thereby utilizing all three
dimensions of the water. There is
no doubt that more use can be made
of effluents from electrical power
plants, especially at the cooler lati-
tudes where ponds or tanks using
the warm-water effluent from gener-
ating stations can greatly lengthen
the growing period of fish and shell-
fish.
A number of research projects
on mariculture are providing much-
needed research results. At the Flor-
ida Power and Light Company's new
power plant, about forty miles south
Figure VIII-11 —SCHEME
FOR USING SE
:WA
GE IN AQUACULTURE
4
Detritus (feces
pseudo feces)
Feeders:
sandworms
microcrustacea
IT
1
Sediment:
coarse sand,
fine clay,
organic
Seawater
and
Nutrients
(artificial
or sewage)
2
Phytoplankton
(natural
populations
of unialgal
cultures)
3
Filter Feeding
Herbivores:
oysters
clams
mussels
scallops
5
Macroscopic
and/or
Epiphytic
Algae
6 Browsing
Herbivores:
post larval
lobsters, shrimp,
and juvenile
mullet
\
\
/
/
\
7
Carnivores:
juvenile
flounder and
striped bass
/
The diagram summarizes a continuous-flow food chain that may be operated in
various permutations and combinations depending on the desired result. The
system consists of the following components:
(1) Diluted (about 10%) sewage effluent as a growth medium for (2) a continuous
culture of natural, mixed phytoplankton. which is harvested at the rate of 50%
of the culture per day and passed through (3) suspended cultures (strings or
racks) of filter-feeding bivalve mollusks (oysters, clams, mussels, or scallops),
the phytoplankton diluted with filtered running seawater and so presented
to a sufficient number of mollusks that almost all of the suspended algal cells
are removed from the water by the animals. (4) Feces and pseudo-feces
produced by the mollusks are deposited on the surface of the sand substrate
of the animal culture tanks where this material is fed upon by sandworms,
bloodworms, and/or other deposit feeders.
(5) Water flowing through the mollusk compartment containing inorganic and
organic nutrients regenerated by the animals is passed into an additional
chamber containing macroscopic algae and/or epiphytic, filamentous algae
which utilize the regenerated nutrients. (6) The epiphytic algae and asso-
ciated microbiota serve as food for browsing animals such as juvenile
lobsters, shrimp, mullet, or other suitable animals.
(7) Although not part of a continuous-flow system, when steady-state equilibrium
conditions are reached, animals from any of the above compartments may be
fed to carnivores (juvenile striped bass, flounder, and lobsters are examples
of readily available species) on a daily-ration basis, the success of this stage
being dependent upon the operation of a large enough system to provide
a constant supply of food over a sufficiently long period of time to the
carnivores.
252
ESTUARIES AND COASTAL ZONES
of the University of Miami's Institute
of Marine Sciences, researchers are
developing techniques to rear pink
shrimp. There are seven ponds,
which range from one-quarter acre
to one acre, and a hatchery building
wherein the stock is raised from egg
to adult through the difficult larval
stages. The questions that research-
ers are asking is whether it is pos-
sible to mass-produce pink shrimp
with high survival and rapid growth
rates on an economic basis, what is
the best food for these shrimp, and
what are the costs for food and
labor. This research began a year or
two ago, and progress has been grati-
fying. Large numbers of young, es-
timated at about 10,000, have been
reared from the egg.
Shrimp are also being raised to
market size in ponds and fenced-off
portions of a bay by a newly formed
company, near Panama City, Florida.
In this operation, between 10 and 20
million brown shrimp have been
reared from the egg to post-larval
stages.
In a number of National Marine
Fisheries Service Laboratories (St.
Petersburg Beach, Fla.; Oxford, Md.;
Milford, Conn.; Panama City, Fla.;
and Galveston, Tex.), research on
mariculture beneficial to industry is
being carried out. At state universi-
ties on the Gulf of Mexico and up the
east coast of the United States, re-
search is also being conducted on
desirable species to provide industry
with baseline information to allow
them to carry out commercial opera-
tions in sea farming.
At the University of Miami's In-
stitute of Marine Sciences, a graduate
student has succeeded in rearing thir-
teen species of marine fish up to
their juvenile stages from eggs caught
drifting in the sea. Sea trout and
flounder are included in the list and
should attract the attention of sea
farmers.
There is high hope for increased
study of aquaculture, but much more
research and investment will be nec-
essary before the important answers
are available for making decisions on
the economic advisability of entering
aquaculture on a large scale.
253
PART VIII — AQUATIC ECOSYSTEMS
4. DYNAMICS OF LAKES
Lake Circulation Patterns
Lakes are large bodies of water
which would he mostly stagnant ex-
cept for the "stirring" influence of
wind on their upper surface. In rare
cases, lakes are part of a river system
and the flow of water through them
drives a pattern of circulation, while
small heated ponds can have their
own thermally induced circulations.
In most other lakes, however, includ-
ing the North American Great Lakes,
wind stress is the prime mover of any
"circulation" (i.e., more or less or-
ganized motions) and "mixing" (i.e.,
random motions leading to the dis-
persal of an admixture).
Man uses lakes for several pur-
poses. Most important, perhaps, is
the "aesthetic" use (building a house
on a lakeshore), closely coupled to
a "recreational" use (swimming,
boating, etc.); lakes are also used
as a source of food (fisheries), of
fresh water supply, as a sink for
waste materials (sewage), and for
waste heat (power generation). Some
lakes also serve as waterways. These
uses conflict to some degree, and
optimizing the use of, say, the Great
Lakes is not a simple problem. For
example, in many places around the
Great Lakes, the only present alterna-
tive to using the lakes as a waste-heat
sink for power generation is to build
cooling towers, which would increase
the costs of power generation quite
appreciably. At the same time, it is
not certain whether or how far the
discharge of large quantities of warm
water into the Great Lakes would
have undesirable consequences for
some other use of these lakes.
Conflicts between different lake
uses are alleviated by lake "circula-
tion" and "mixing." For example,
none of the Great Lakes is in any
sense "polluted" as a whole at pres-
ent, although the water near the
shores certainly is in many places.
The difficulty is that the pollution
is usually concentrated in an "in-
fluence zone" near an effluent source,
which is usually located at the shore.
If all waste matter and waste heat
discharged into a lake were mixed
with its entire body of water, there
would be far less interference with
other lake uses — although there are
clearly limits to the advantage to be
obtained in this manner.
The main cause of circulation and
mixing in most lakes is the stress
that the wind exerts at the air-water
interface. The actual patterns of cir-
culation are also determined by the
shapes of the basins, the thermal
(density) structure of the water, and,
for large lakes, the rotation of the
earth. The problem is basically one
of physical oceanography (or physical
"limnology," to be precise, although
the behavior of lakes is usually dis-
cussed in the oceanographic litera-
ture). However, heat by solar radia-
tion, evaporation heat loss (both af-
fecting density structure), and wind
stress are inputs the knowledge of
which comes from meteorology.
Evaluation of Current Knowledge
Generally speaking, problems of a
meteorological nature are better ex-
plored than those of the oceano-
graphic kind. Most existing knowl-
edge on physical limnology was
developed in connection with bio-
logical studies, witness the highly
authoritative Treatise on Limnology
by Hutchinson. Indeed, several emi-
nent workers in physical limnology
started their careers as biological
limnologists. Inevitably, then, the
character of existing knowledge re-
flects a certain bias toward problems
of biological importance. For ex-
ample, the annual cycle of tempera-
ture distribution in lakes (which has
a direct bearing on life processes) is
well explored, while the dynamics of
medium- and large-scale motions is
poorly understood. "Meteorological
inputs" are also better known. While
it would be a gross exaggeration to
say that the problem of predicting
wind stress over a water surface is
solved, we can make a much closer
estimate of this stress than of the
speed of the current produced by it.
Wind Mixing — In greater detail,
the "wind mixing" of the top layers
of lakes, their yearly cycle of "over-
turn," and similar "local" phenomena
are fairly well documented, even if
the basic mechanics of these processes
(e.g., the formation of steep "steps"
in the thermocline) are only now be-
ginning to be investigated. Inspiring
fundamental work in this area has
recently been reported from the Med-
iterranean and the Great Lakes and
from laboratory simulation. These
studies have been complemented by
results obtained through computer
modeling in connection with the nu-
merical forecasting of ocean circula-
tion. The small-scale structure of
turbulence, of internal waves, their
"breaking" and interaction with tur-
bulence (leading to vertical mixing,
particularly across the thermocline)
are highly relevant to the mixing
problem and are under investigation
in a few places.
Wave-Like Motions — Among the
large-scale motions in lakes, the best
understood are the "seiches," or regu-
lar surface oscillations, usually started
by bursts of wind. Perhaps the most
prominent example is provided by the
seiches in Lake Erie, which acquire
economic importance due to their
effect on the output of the Niagara
power plant.
254
DYNAMICS OF LAKES
Internal waves and seiches of large
scale often play an important role in
the circulation of moderate to large
lakes. In the Great Lakes, it has re-
cently been demonstrated that in-
ternal waves dominate the flow
regime during summer in the central
portions of the lakes — i.e., away
from the shore zones. It is generally
assumed that the energy of these
large internal waves is degraded into
smaller-scale motions that produce
mixing. But there is a complete ab-
sence of information on how this
degradation takes place; as a result,
we don't know on what days to ex-
pect or not to expect "good" vertical
or horizontal mixing.
Another completely obscure aspect
of internal waves is the mass trans-
port they cause. Individual particles
execute back-and-forth motions in
waves, often over a period close to 17
hours, but there is also a residual or
"transport" motion on top of the
wave-induced movements. The latter
determines the bulk motion of any
admixture to the lake, and next to
nothing is known about it (in con-
trast to actual, instantaneous current
velocities, which have been measured
frequently and in many places). In-
deed, lack of information on mass
transport in a flow regime dominated
by wave-line motions (particularly in-
ternal waves) may be said to be the
greatest single "gap" in knowledge
concerning circulation problems in
lakes, particularly in the Great Lakes.
Currents — Persistent currents are
usually weak in lakes, including the
Great Lakes, with the possible excep-
tion of Lake Ontario, wherein the
Niagara River plume may perhaps be
classed a "current." Apart from this,
the possibility exists that long, slow
internal waves of the "Kelvin" type
produce fairly concentrated currents
with a lifetime of at least several
days.
Recent work has indicated the ex-
istence of such quasi-permanent cur-
rents near the shores of some of the
Great Lakes, but the evidence is far
from conclusive. Observed currents
at moored stations in the shore zone
of the Great Lakes show a greater
degree of persistence than in the cen-
tral portions of the lakes, but the
spatial and temporal current structure
is too complex to allow reliable gen-
eralizations at present. Indeed, one of
the main conclusions one may draw
from recent work on coastal currents
is that the details are too complex,
and an experimental technique aimed
at the determination of bulk mass
transport in the shore zones (some
appropriate tracer technique, for ex-
ample) should provide more useful
information than further direct cur-
rent measurements, requiring the de-
ployment of a large number of
meters. Another important point is
that current structure around the
shores of the Great Lakes is different
from place to place as well as from
season to season — yet we know little
about current or mass transport "cli-
matology" even though this is most
important in connection with the use
of the lakes by man.
Some turbulent diffusion experi-
ments have been carried out in the
Great Lakes recently, simulating sew-
age outfall and warm effluent dis-
charges. The data are mainly relevant
to an initial phase of dilution (just
after leaving the discharge), and even
in this connection it is not certain
that the diffusive properties deter-
mined would be similar to those in
other locations, where the current
structure may be radically different.
On large-scale mixing, data are quite
scant, but what information there is
appears to show that any effluents
discharged in the shore zone tend to
remain there for several days (a
phenomenon termed "coastal entrap-
ment"). Indeed, it is not at all clear
what the physical mechanisms are
by which coastal waters mix with the
main body of the lake.
There is little or no direct informa-
tion on the connection between cer-
tain conspicuous thermal features of
the lakes (upwellings, the "thermal
bar" during the warm-up period)
and any current structures that may
be associated with them. However,
theory suggests that some strong cur-
rents may accompany marked ther-
mal features of this kind. It is also
obvious that a sudden appearance or
disappearance of upwelling along a
shore has an influence on the water
exchange between the shore zone
and main lake mass. (See Figure VIII-
12) Similarly, the fate of heated
effluent may be very different from
that of effluent with no thermal
effects, because warmer and lighter
water may "slide out" over the rest
of the lake and assume a flat lens-like
shape. Such phenomena are known
to occur in rivers and estuaries but
no detailed observations in lakes seem
to be available.
Modeling and Instrumentation
Mathematical modeling of circula-
tion and mixing in lakes (specifically
the Great Lakes, or at any rate lakes
large enough for the rotation of the
earth to be important in their dy-
namics) is in its infancy, but some
good first steps have been taken in
the past twenty years or so. Numeri-
cal modeling on the lines suggested
by atmospheric work should be com-
paratively easy (a two- or a three-
layer model should be adequate), the
main problem being to display the
multitude of results in an intelligible
form. It should be added, however,
that no mathematical modeling has so
far even been suggested for the main
variable of practical interest, the total
mass transport in the shore zone (due
to currents and wave-like motions).
The instrumentation available for
experimental work in physical limnol-
ogy has not kept pace with modern
developments in other fields of sci-
ence. One agency reported that it
had a 40 percent useful return rate
from its own moored current meters
during the 1969 summer season —
a completely unacceptable situation
which is nevertheless quite universal.
Available current meters are not suf-
ficiently sensitive at low speeds; they
255
PART VIII — AQUATIC ECOSYSTEMS
Figure VIII-12 — UPWELLING OF COASTAL LAKE WATERS
^ WIND ^
(1)
»- -►
»~
(3)
> v V V V V J ? \
\ V O f
V
V
^ <>
NEGLIGIBLE FLOW
(4)
20-
40-
60-
WINDERMERE NORTHERN BASIN
26 OCT. 1949
The circulation and upwelling produced by the stress of a steady wind on a small
lake is shown hypothetically in sketches (1) to (3). In diagram (4) the actual
thermal distribution is shown after 12 hours of wind stress. At the upwind end
of the basin, the thermocline intersects the water surface.
are not at all accurate in a wave zone.
An important recent addition to in-
strumentation has been the airborne
infrared thermometer, which should
be exploited more systematically in
the future. Apart from this instru-
ment and the fluorometer used in
diffusion studies, we are still relying
on crude, ancient devices quite un-
worthy of the Space Age.
Scientific Recommendations
A most encouraging recent devel-
opment is that many fluid dynami-
cists previously in aerospace research
are turning their attention to lake
dynamics. This should be encour-
aged to the fullest possible extent.
The full understanding of the basic
dynamics of lake motions (where di-
rect effects of turbulence are un-
important) should be well within the
reach of fluid dynamicists today, and
should also provide important in-
sight into the somewhat less manage-
able problem of ocean dynamics.
Further, studies of internal zoaves and
turbulence (including their interac-
tion) also promise to be fruitful for
the understanding of mixing proc-
esses, particularly mixing through
stable layers. At the same time,
knowledge so gained is also relevant
to certain atmospheric problems, no-
tably to the understanding of clear
air turbulence. Experimental studies
of internal waves and turbulence are
more easily done in a lake than
30,000 feet up in the atmosphere.
From a practical point of view, the
greatest urgency attaches to coastal-
zone studies of mass transport, cur-
rents, and diffusion. Present knowl-
edge in this field is quite inadequate
for even the crudest engineering de-
cisions. For example, the cooling-
water system for a large power plant
next to one of the Great Lakes was
designed on the basis of an under-
estimate of "typical" current speeds
by an order of magnitude; as a result,
the cooling water in that plant now
frequently recirculates from outlet to
intake, raising the cooling-water tem-
256
OF LAKES
perature, with deleterious effects on
efficiency. Immediate and systematic
work is required on the climatology
of coastal currents at various loca-
tions and in various seasons. Also,
it is necessary to conduct a long
series of large-scale diffusion experi-
ments to define the likely "influence
zones" of potential effluent outlets,
again as a function of location around
lakes, particularly the Great Lakes.
Given the present dearth of knowl-
edge, it would take perhaps ten years
of concentrated effort to achieve some
sort of consensus on the most urgent
topics (climatology of currents and
influence zones) that affect the most
important of our lakes, the Grea'
Lakes. It may take 25 years to build
up a solid enough base of funda-
mental knowledge (dynamics of cur-
rents, mass transport, internal waves,
turbulence, and mixing) for the con-
struction of more detailed prediction
models for long-term planning and
"resource management."
The Effects of Thermal Input on Lake Michigan
Our concern for the environmental
quality of the Great Lakes arises from
their relatively closed condition. The
lakes serve as channels for internal
navigation, as highways to the
world's oceans, as sources of water
for cities and industries, including
electric power, as recreational re-
sources — and as sinks for the water-
borne wastes from urban and agri-
cultural land. As the multiple uses
increase, problems appear. In spite
of its large volume and generally
good water quality, some parts of
Lake Michigan — for example, south-
ern Green Bay and some harbors
near Chicago — are becoming grossly
polluted; this is a development that
the public is not prepared to tolerate
any longer. The threat to environ-
mental quality is a direct consequence
of the multiple uses to which the
lakes are put and of the rapid rise
of population over the last century,
particularly in the southern half of
the region.
With present agricultural practice
and systems of waste disposal, the
Great Lakes — whether we like it or
not — are the receptacles of waste
products of all kinds, some of them
long-lived. They are becoming over-
loaded beyond their natural capacity,
in some places intolerably so. Is this
an inevitable consequence of a large,
highly industrialized civilization with
a high standard of living? It need not
be so, if we are willing to pay the
price in regulatory planning and in
dollars to maintain reasonable stand-
ards of water quality and to work
with nature rather than against it.
It should be noted that water quality
remains high in the northern part of
Lake Michigan and in Lake Superior.
This represents a national treasure
that must be conserved and wisely
managed for posterity.
Heat Dissipation Projected
to 1990
One form of waste is waste heat.
This particular use of Lake Michi-
gan's waters is expected to grow
rapidly with growing power demands
by industry and by home-owners and
institutions seeking to improve their
interior environments (e.g., through
airconditioning). The question is
whether the price we pay for this
must include biological deterioration
of the lake.
It is perhaps not generally realized
that some of the largest generating
plants in the country already use Lake
Michigan for cooling. The 1970 col-
umn in Figure VIII— 13 indicates that
the equivalent of 16,000 megawatts
is added to the lake in the form of
heat at present. According to a fore-
cast by the Argonne National Labo-
ratory, this figure is expected to be
nearly doubled by 1975, when further
large units (many of them nuclear
generating stations) now under con-
struction or being planned come into
operation. Beyond that, projections
of the increase are largely guesswork,
but must presumably bear some re-
lation to the projected rise in national
demand, forecast as doubling every
ten years up to 1990. If this demand
is to be met, it will be done with
larger units, mainly nuclear, and
these need large heat sinks to operate
at maximum efficiency. There are
only three heat sinks with sufficient
capacity: the ocean, the atmosphere,
or (for the Midwest) the Great Lakes.
The interest of power companies in
Lake Michigan is, therefore, not sur-
prising.
Effect on the Lake
Even allowing for improvements in
thermal efficiency, heat dissipations
from Lake Michigan for 1970, 1980,
and 1990 are likely to increase at a
rate that slightly more than doubles
every ten years. (See Figure VIII-13)
If these estimates are accepted as rea-
sonable, we may calculate the orders
of magnitude of the effect on the
lake. This has been done in three
ways in Figure VIII-13. A typical
daily total of heat input from the sun
in early summer is 300 of the units
used in the figures (gram-calories per
square centimeter of lake surface).
The daily total heat output from
power stations in 1990 is less than
one percent of this, if spread over
the whole lake surface. But this is,
of course, unrealistic, bearing in
mind that all the heat is injected near
shore.
257
PART VIII — AQUATIC ECOSYSTEMS
Figure VIII— 13 — THERMAL INFLUENCE OF
ELECTRIC POWER GENERATION ON LAKE MICHIGAN
1970
1975
1980
1990
Power to be dissipated, in units
of 1000 megawatts, as heat
16
28
37
75
Equivalent daily heat input,
g-calories per cm2 of:
(i) whole lake surface
(ii) inshore strip (depth less
than 10 m = 33 ft.)
0.57
7
1.0
12.5
1.3
16
2.6
33*
Equivalent temperature rise °C,
assuming a 10-day storage and
complete mixing into:
(i) whole lake volume
(ii) inshore strip (depth less
than 10 m = 33 ft.)
0.0007
0.14
0.0012
0.25
0.0016
0.33
0.0032
0.66
Equivalent evaporation increase
as decrease in lake level (cm
per annum), assuming all heat
lost through evaporation
0.34
0.62
0.81
1.63J
* 5-10% of a summer day's natural heat input into the
t equals 1/20 ft., about 2% of natural evaporation, i.e.,
inshore strip.
less than the annual variability.
The table shows estimates of the effect of heat input into Lake Michigan due to
waste heat from the generation of electric power. These effects are indicated in
terms of an increase in lake temperature and an increase in evaporation.
If we consider only the inshore
strip of water (of depth less than 10
meters, or 33 feet), which covers
8 percent of the lake area, the picture
looks different. In that case, the
daily total input of heat from power
stations for every day of the year
by 1990 would be about 10 percent
of the sun's input on a summer day.
Temperature Rise — Another way
of looking at the matter is to con-
sider the temperature rise of the
whole or part of the lake attributable
to power-station inputs. This is a
much more complicated and uncer-
tain calculation, because of lack of
knowledge of the rate of dispersion
and of how long the heat stays in the
lake before it is lost to the atmos-
phere, or to space by back-radiation,
or to increased evaporation. This re-
tention time is a statistical estimate
in any case; it is certainly greater
than one day and probably less than
30, so a guess at 10 days seems not
unreasonable. With that guess we
find, again, that the effect on the
whole volume of the lake is negligible
but that the effect on an inshore
water strip is appreciable. For ex-
ample, the temperature rise of the
inshore strip, based on these assump-
tions (10-day storage and complete
mixing into this inshore volume),
would amount to 0.7 centigrade —
i.e., a little over 1° Farenheit by 1990.
These estimates do not, of course,
take into account any major engi-
neering changes or advances in de-
sign leading to better thermal effi-
ciency.
The significant conclusion from
this is that, because the heat input
takes place at a number of point
sources, there will be measurable
temperature rises locally but the aver-
age effect on the whole lake will not
be substantial. It is with local effects,
then, that we must be concerned.
Natural Phenomena — The natural
temperature regime of the coastal
water is complex. In summer, there
is sporadic upwelling of cold bottom
water, depending on the stress of the
wind over the whole lake, coupled
with the effects of the earth's rota-
tion. The temperature at near shore
intakes (for example municipal water
plants) can sometimes change by
many degrees in an hour.
Another phenomenon that adds to
the complexity of coastal circulation,
and which is not this time dependent
on changes in the wind, is the so-
called thermal bar. This is most
marked in spring, when the shallow
water near shore is warming up to
temperatures above that of maximum
density (4"C), while the offshore
waters remain at their winter tem-
perature below 4° centigrade. Where
the warmer inshore and colder off-
shore waters mix, a water mass is
formed close to the temperature of
maximum density. This mixture is
heavier than the original inshore and
offshore water masses from which it
was formed, and it therefore sinks.
This continually sinking water mass
(a convergence) forms a temporary
barrier to horizontal mixing between
inshore and offshore waters. At the
same time, the convergence is a rather
efficient way of carrying water (and,
therefore, heat) from the surface into
the deeper regions of the lake.
As the spring heating continues,
the thermal bar migrates further and
further offshore until, usually some
time in June, the summer thermal
stratification is established right
across the lake. At times when the
thermal bar is strongly established,
water may be trapped inshore for
several days or weeks. The effect of
thermal discharges into that trapped
water mass is a matter for conjecture.
But it seems likely that situations
258
DYNAMICS OF LAKES
could arise, at least on particular days
in the year, when the thermal plume
from an electric power station would
travel along the shore for a long dis-
tance with relatively little dilution,
rather as a plume from a smokestack
is visible for miles when there is a
temperature inversion in the atmos-
phere.
Evaporation — Although we have
emphasized the local, near shore ef-
fects and minimized those offshore,
there is one whole-lake consequence
of larger thermal additions. This
emerges when we consider the final
fate of the added heat. A large part
of it will be used in increasing evapo-
ration above the natural level, al-
though some will, of course, be lost
by back-radiation and heat exchange
with the atmosphere.
If we make the worst assumption,
from the point of view of water con-
servation, that all the heat is lost
through increased evaporation, the
estimated power dissipation in Figure
VIII— 13 can be translated directly into
water loss. Tabulated as centimeters
of water lost from the whole lake sur-
face per year, the loss rises to 1.63
centimeters, or about l/20th of a
foot, in 1990. Integrated over the
whole lake surface, this is an impres-
sive volume and, in fact, represents
about 2 percent of the mean outflow
of Lake Michigan, which is 46,000
cubic feet per second, and about 2
percent of the estimated annual na-
tural evaporation. Some of this will,
of course, be returned to the lake by
later precipitation. It should be noted
that the proportion of heat (and
therefore water) lost through evapo-
ration would be greater if cooling
towers were used.
Needed Research
We need to be able to predict the
local thermal effects with more pre-
cision and, in particular, to study the
way in which the hot plume disperses,
paying particular attention to rates
of diffusion. In Lake Michigan this
should be much more than an engi-
neering study through physical or
numerical models. It should also in-
clude an in-lake hydrographic study,
because the current regime and conse-
quent diffusion in the lake itself
varies greatly. And we need to ex-
amine not only the average long-
term circulation patterns, but also the
fluctuating circulation patterns asso-
ciated with such temporary phenom-
ena as upwelling, internal waves, and
thermal bars. There are a number of
mechanisms that sometimes tend to
keep water near shore for days or
weeks. This is not to say that the
lake is not well mixed at other times;
indeed, at least once a year, in Janu-
ary, it is probably very thoroughly
stirred. But we must also consider
the consequences of rare types of cir-
culation with minimal diffusion — for
example, under extreme thermal-bar
conditions — which may develop per-
haps once every ten years.
And then, of course, there are pos-
sible biological effects. We clearly
need surveys to identify biologically
sensitive areas. We could learn much
by carrying out some of these surveys
near existing large fossil-fueled sta-
tions. These have been operating for
years, but no one seems to have re-
ported major deleterious effects on
Lake Michigan. We should certainly
look and see if there are any; we
should also try to differentiate be-
tween true thermal effects and those
arising from material wastes, looking
also for interactions, harmful or bene-
ficial, between thermal discharges and
more conventional pollution.
At the same time, there should be a
thorough search of the literature.
There is a large body of published
material, including that from Atomic
Energy Commission (AEC) labora-
tories or AEC-supported work, on
the effect of radioactive materials and
thermal discharges on organisms.
The public is clearly thirsting for
knowledge on this subject, and anno-
tated bibliographies would be most
useful. We hear a great deal of loose
talk about the harmful effects of
radioactive and thern; urges,
so we should at least know what has
been done before we decide which
research gaps need filling.
Special studies should be made in
the biological field. These should be
concerned with concentration effects,
already mentioned, and with the in-
fluences to which aquatic organisms
are subjected in a fluid in which,
while the levels of radioactivity may
be very low, they spend the whole
of their lives.
Engineers and others should be
encouraged to collaborate in pilot
studies leading to the beneficial use
of waste beat. A number of ex-
ploratory projects are already under
way: irrigation of fruit orchards to
avoid frost damage; fish culture;
raising the efficiency of other waste-
disposal systems.
Finally, we come to planning and
to the value judgments that planning
entails. There is a great need for
over-all regional planning, for ex-
ample to decide on the siting of new
nuclear power stations. They must
avoid biologically sensitive areas
(e.g., fish breeding grounds), they
should not be grouped to aggravate
the thermal effects, and if possible
they should be placed where they
could be useful. If, for example,
waste heat could be used to keep the
St. Lawrence Seaway open for a few
more weeks in winter, that would
permit overseas shipping lines to
make one more run per year to the
Great Lakes — a tangible benefit.
With competent and imaginative
research and planning and with in-
telligent siting of power stations, it
should be possible to enjoy the bene-
fits of nuclear power without threat
to other users or to our enjoyment
of the Great Lakes. The research
should include not only the study
of near shore water circulation and
the ecological consequences of the
temperature rise, but also advanced
engineering leading to beneficial uses
of the waste heat. Design and plan-
259
PART VIII — AQUATIC ECOSYSTEMS
ning must seek a high rate of heat last point has perhaps not been suf- generation. In view of the tendency
dispersal by turbulence, avoid bio- ficiently stressed. Power stations will to build larger and larger stations
logically lethal high temperatures, have a permanence and remain a away from population centers, it can
prohibit construction in biologically safety responsibility far beyond the be argued that the threat to the
sensitive areas (to be identified), and short design life of the reactors. They landscape is greater than the threat
preserve landscape amenities. The will be monuments to our present to the lake.
260
5. LAKE EUTROPHICATION AND PRODUCTIV
Fishery Deterioration in the Great Lakes
Before human settlement, the wa-
ters of the Great Lakes abounded in
fish characteristic of large lakes with
cold, clear water. But the fish popu-
lations and the environment of the
Great Lakes have undergone pro-
gressive deterioration for more than
a century. Degradation has acceler-
ated at an alarming rate in recent
years. Valuable fish such as Atlantic
salmon, lake trout, whitefish, blue
pike, and walleye comprised 80 to
90 percent of the production of the
early fishery; but in recent years
these species have contributed less
than 5 percent of the catch from the
lakes in which they are still present.
(See Figure VIII-14)
The Great Lakes, 64 percent of
which lie within U.S. boundaries,
cover 95,000 square miles and are
the largest and most valuable fresh-
water resource in the world. The
fish populations constitute the great-
est and most valuable renewable re-
source of the lakes. Peak U.S. fishery
production occurred around 1900,
when 100 to 120 million pounds of
mostly high-value species were taken
annually. The catch subsequently de-
clined. In 1963, it reached a low of
less than 53 million pounds — com-
posed primarily of medium- and low-
value species (alewives, carp, chubs,
perch, sheepshead, smelt, and suck-
ers).
Causative Factors
Until recently, the causative fac-
tors of this drastic change have been
a subject of great controversy. It is
now known that modifications of the
drainage by agriculture, urbanization,
and industrialization, and intensive,
selective fishing for the most valuable
species have caused major changes
that led to invasions of new species
and deterioration of water quality.
The exact ways in which these in-
fluences have affected individual spe-
cies or groups of species are not yet
completely understood. Careful re-
view of the entire sequence of events
within the Great Lakes and their
drainage, however, is providing in-
formation essential to the formula-
tion of environmental criteria and
elaboration of management plans
that can be implemented to reverse
undesirable trends and restore much
of the value of the Great Lakes and
their fisheries.
Settlement of the Lake Ontario
basin and the construction of the
Erie and Welland canals were the
events that initiated a chain reaction
that has now upset the ecological
balance of fish populations through-
out the Great Lakes. As noted, Lake
Ontario and the St. Lawrence River
were once inhabited by an abundance
of cold-water species dominated by
the Atlantic salmon. Early accounts
describe how the cutting of the for-
ests and agricultural development
increased water temperatures and
lowered flows of streams in which
Atlantic salmon spawned. Mill dams
blocked spawning streams. Disposal
of mill wastes in streams, as well
as intensive fishing, also contributed
to a sharp decline of Atlantic salmon
during the mid-1800's.
The salmon were scarce by 1880
and extinct by 1900. Repeated at-
tempts to re-establish them have
Figure VIII-14 — COMMERCIAL FISH CATCH: LAKE MICHIGAN
100
60
O
o
40 -
O 30
-
LAKE TROUT
-
LAKE HERRING
SUCKERS--/ /
-" WHITEFISH /
-
YELLOW PERCH -^V/
£
s\ CHUBS /
/-— — ^ carp ^-^\^y
=—
SMELT /"""^
-/"" ALEWIFE
1 1 1 1 1 1 1 1 1 1 1 1 1 1
1898- 1910-
1909 1919
1920- 1930- 1935- 1940- 1945- 1950- 1955- 1960 1961 1962 1963 1964 1965 1966
1929 1934 1939 1944 1949 1954 1959
The diagram shows statistics of the commercial fish catch on Lake Michigan
from 1898 to 1966. The degradation of the fish population is clearly evident;
although the total catch returned to turn-of-the-century levels in 1966, almost all
of it consisted of alewives and other low-value species.
261
PART VIII — AQUATIC ECOSYSTEMS
failed. Even though a salmon fishery
no longer existed and the problems of
mill dams and pollution had been
eliminated in most streams, the lower
flows and warmer waters continued,
indicating that removal of timber
and agricultural development within
the drainage had created conditions
that made the region unsuitable for
survival of the Atlantic salmon.
Effects of Marine Invaders — Elim-
ination of the Atlantic salmon, which
was the major fish predator of Lake
Ontario, created conditions favorable
for the entrance of the alewife,
which was the first and most de-
structive marine invader. As the sal-
mon were declining, the alewife was
entering the Lake Ontario drainage
via the Hudson River and the Erie
Canal. By 1868, alewives had be-
come abundant in the Canal and in
the Finger Lakes, which drain into
Lake Ontario. Large schools of small
alewives were reported in Lake On-
tario in 1873 — by which time the
Atlantic salmon had been reduced
greatly. The lake trout was another
major fish predator in Lake Ontario,
but it, too, was declining during this
period, possibly due to heavy ex-
ploitation.
More recent experience in the other
Great Lakes has shown that the small,
landlocked alewives are unable to
thrive when any of the Great Lakes
is densely populated by larger fish
predators. Without predators, how-
ever, the alewife in Lake Ontario
was able to increase rapidly; it had
become the most abundant fish by
1880. Furthermore, by 1900, the ale-
wife had greatly reduced or virtually
eliminated all of the previously abun-
dant small species of Lake Ontario
that depended on plankton during
at least part of their lives; as past
studies have shown, the alewife has
a strong competitive advantage over
native freshwater fish that also feed
on zooplankton.
The alewife used the lake much
less efficiently than native species,
causing a reduction in the total
amount of fish in the lake. The
previously abundant native species
had occupied all zones of the lake
during the entire year. In contrast,
the alewife ranged throughout the
lake in dense schools but occupied
different portions of the lake in vari-
ous seasons; under its dominance,
the vast deep-water region repre-
senting 70 to 80 percent of the area
of the lake was unoccupied by other
species during most of the year.
The parasitic sea lamprey was the
second marine invader of the Great
Lakes. It had free access to Lake
Ontario via the St. Lawrence River
but it did not become established in
Lake Ontario until the 1880's. Con-
ditions that made the lake unfavor-
able for the Atlantic salmon appar-
ently made it suitable for the sea
lamprey. The inland ranges of the
two species do not overlap — the
Atlantic salmon favors drainages that
have durable, cool streams suitable
for its fall spawning, while the
spring-spawning sea lamprey favors
streams that become warm following
the spring runoff.
Once the Atlantic salmon, which
fed on small fish, was eliminated,
the sea lamprey, which feeds on
large fish, became the dominant pred-
ator; once established in Lake On-
tario, it prevented any sustained re-
surgence of lake trout, whitefish, or
larger species of deep-water ciscoes
(commonly called chubs by fisher-
men of the Great Lakes). Thus, the
combined effect of the invasions of
the alewife and the sea lamprey was
to reduce drastically the fishery pro-
ductivity of Lake Ontario.
If it were not for the Welland
Canal, which provides a waterway
that bypasses Niagara Falls and al-
lows access to the upper lakes, the
destructiveness of these marine in-
vaders would have been limited to
Lake Ontario. Both the sea lamprey
and the alewife were able to nego-
tiate the Welland Canal, however.
The sea lamprey reached Lake Erie
by 1921, was established in Lake
Huron in 1932, Lake Michigan in
1936, and Lake Superior in 1946.
The alewife first appeared in Lake
Erie in 1931, Lake Huron in 1933,
Lake Michigan in 1949, and Lake
Superior in 1954.
Neither the sea lamprey nor the
alewife became a severe problem in
Lake Erie, which had few suitable
spawning streams for the lamprey
and had substantial populations of
predators to keep alewife abundance
low.
Conditions in Lakes Huron, Mich-
igan, and Superior favored the lam-
prey and alewives, however, and
these lakes were to suffer fates sim-
ilar to that of Lake Ontario. The
influences of the lamprey and alewife
occurred in the reverse order. As the
lamprey became established in each
of the upper lakes, it destroyed the
lake trout that was the major fish
predator of the upper Great Lakes.
Loss of the lake trout was followed
by establishment and rapid increase
of the alewife population. In Lakes
Michigan and Huron, the destruc-
tion of large fish by the sea lamprey
and small fish by the alewife became
as severe as in Lake Ontario.
Development of a chemical method
of sea-lamprey control was first ap-
plied in Lake Superior and prevented
the complete collapse of the lake-
trout population that had occurred
in Lakes Michigan and Huron. Al-
though present control methods have
not been sufficient to permit restora-
tion of significant spawning stocks
of lake trout in Lake Superior, sus-
tained introductions of hatchery-
reared trout have held the alewife
in check.
The status of Lake Superior re-
mains uncertain, however, as sea lam-
preys are thriving; the sparser popu-
lations resulting from the control
measures have enabled the lamprey
to reproduce more prolifically than
ever. The remnant lamprey pop-
ulations pose a serious threat to
rehabilitation of a reproducing popu-
262
LAKE EUTROPHICATICN AND PRODUCTIVITY
lation of lake trout and to the abun-
dance of other large native species ■ —
whitefish, lake herring, and larger
deep-water ciscoes — as well as to
the recently introduced coho and
chinook salmon.
In summary, the invasion of ma-
rine species made possible by eco-
logical disruption during settlement
of the Lake Ontario basin in the
1800's has been a major contributing
factor to substantial reduction of the
fishery productivity of Lakes On-
tario, Huron, and Michigan, and the
ultimate effects on Lake Superior are
still uncertain.
Effects of Deteriorating Water
Quality — The most serious threat
to the biological stability and fishery
productivity of the Great Lakes has
been a progressive deterioration of
water quality. During early settle-
ment within the Great Lakes drain-
age, organic pollution characteristic
of nonindustrialized society fouled
tributaries of the Great Lakes; it had
virtually eliminated populations of
river-run lake trout, whitefish, lake
herring, walleye, yellow perch, and
sturgeon by the late 1800's and early
1900's. These populations made up
a major segment of the total fish
stocks in the lakes and they have
never recovered.
More recently, there has been in-
creasing evidence that a much more
ominous type of pollution has ac-
companied advanced industrializa-
tion. This "new" pollution consists
of discharges of complex chemical
and physical wastes from advanced
industrial, agricultural, and urban ac-
tivities, and from massive releases
of heated waste water from industries
and power-generating plants.
The combined effects of the "con-
ventional" and "new" environmental
contaminants cannot be described or
their influences on aquatic life ex-
plained by existing criteria or meth-
ods. The mechanisms of their in-
fluence on aquatic life are unknown,
but the fact that they have had major
detrimental effects on aquatic life is
beyond question.
Southern Green Bay, Saginaw Bay,
Lake St. Clair, the Detroit River, and
all of Lakes Erie and Ontario are
polluted to the extent that they have
lost virtually all of the "clean water"
species that were once abundant in
them. The sequence in which fish
declined or disappeared and water
quality deteriorated has been the
same in all areas. The lake trout
declined first, followed by lake her-
ring, whitefish, sauger, blue pike,
walleye, and yellow perch. The deep-
water ciscoes are very sensitive to
environmental degradation, but they
decline late in the sequence because
the deep waters are influenced later
than shallow areas by contamination.
Lakes Erie and Ontario have been
the most seriously affected by pol-
lution. These were the two most
productive Great Lakes. The species
of fish characteristic of large northern
lakes were once extremely abundant
in both lakes, but all are now greatly
reduced, rare, or extinct.
Since Lake Erie was not influenced
greatly by the invasions of the alewife
and sea lamprey, the loss of its valu-
able species can be attributed pri-
marily to the complex, yet poorly
understood, effects on aquatic life
of massive introductions of biological,
chemical, and physical wastes of an
advanced industrialized society. Lake
Erie still has large populations of
fish. Sheepshead, carp, and goldfish,
which have little present value or
use, abound in the lake and its bays.
Present biological information shows,
however, that populations of the
more valuable walleye, yellow perch,
and smelt appear to be in imminent
danger of collapse. Fishery produc-
tivity of the large central basin of
Lake Erie has been reduced greatly
in recent years by oxygen depletion
in the bottom waters, which has made
a major portion of the lake uninhabit-
able by fish or fish-food organisms.
The fish populations of Lake On-
tario have been affected more se-
riously than any other Kike. Early
reductions of fish stocks due to in-
fluences of the alewife and sea lam-
prey have been compounded in recent
years by additional reductions caused
by the extreme deterioration of water
quality in Lake Ontario, which is
the ultimate recipient of all wastes
entering both Lakes Erie and On-
tario. The vast deep-water region of
Lake Ontario is devoid of any valu-
able and abundant species of fish.
The native species that supported the
most productive and prosperous fish-
eries of the Great Lakes during the
early and mid-lSOO's have all become
greatly reduced or rare; many are
extinct.
The native species lost in Lake
Ontario due to water-quality degra-
dation — lake trout, whitefish, lake
herring, deep-water ciscoes, deep-
water sculpin — are the only kinds
of fish that thrive in any of the large,
deep lakes of the world. If the water
quality of Lake Ontario cannot be
restored so that it is again favorable
for these species, the lake's fishery
potential will be lost forever. If the
water quality of the other deep
lakes — Michigan, Huron, and Supe-
rior — continues to deteriorate, their
vast deep-water regions will also
become fishery deserts.
Status of the
Environmental Science
Development of an understanding
of the precise causes of the biological
degradation of the Great Lakes is in
the formative stages, and is advanc-
ing slowly in a few scattered problem
areas. Existing techniques and gen-
eral knowledge of present and poten-
tial problems seem adequate to for-
mulate a systems approach that
could, when sufficient monitoring and
research information become avail-
able, describe and predict the biologi-
cal interactions in the Great Lakes
environment and relate biological re-
sponses to activities of man in the
lake basins.
263
PART VIII — AQUATIC ECOSYSTEMS
A few cause-effect relations of en-
vironmental degradation are under-
stood — e.g., the cause of oxygen
depletion in Lake Erie and its relation
to the disappearance of blue pike
and the diminution of other fish and
fish-food organisms in the region of
the lake affected. The relation be-
tween excessive phosphorus and ob-
noxious algae blooms in Lakes Erie,
Ontario, and other scattered locations
has been established. Lake Ontario
is no longer suitable for lake trout
because the clean, rocky spawning
areas essential for its reproduction
are covered by a fibrous mat.
Studies of the effects of chemical
and physical factors on biological
productivity and stability are in pre-
liminary stages for a few species.
Some information is being obtained
on the physical requirements for suc-
cessful incubation and hatching of
the alewife, the sea lamprey, and
some species of the whitefish family.
Thermal stresses and physiological
responses that influence alewife die-
off and abundance are under study.
Problems of species interaction are
incompletely understood and only
a few are subject to adequate study
at present. Information on selective
feeding of the alewife and the result-
ant effects on changes in the com-
position of fish-food organisms gives
clues to possible competitive advan-
tages of the alewife that may explain
the decline of various species when
the alewife becomes dominant. There
is some evidence that more complex
feeding interactions and competition
during certain life stages of smelt,
deep-water ciscoes, and lake herring
may have contributed to the sharp
reduction of lake herring in certain
areas of Lake Superior in the absence
of alewives. The ability of the un-
checked sea-lamprey populations to
destroy a lake-trout population by
eliminating all mature trout has been
documented by detailed studies in
Lake Michigan, but the relation be-
tween lamprey-attack mortality of
lake trout and other large native spe-
cies is not known. Thus, the degree
of lamprey reduction that will be
required to restore substantial stocks
of large species, as a step toward
restoration of a favorable balance of
all fish species, is still uncertain.
Also unknown or uncertain are the
relations of physical, chemical, and
biological change to the declines of
native species throughout the Great
Lakes. These are the species or kinds
of species that must be rehabilitated
to restore the fishery productivity of
the Great Lakes. To prevent dete-
rioration of the lakes from pro-
gressing to the point where biological
and fishery restoration may be ex-
tremely difficult or impossible, control
of environmental degradation and un-
desirable species must be undertaken
before research on cause-effect rela-
tions of the various factors of de-
gradation can be completed. Never-
theless, the research must be initiated
expeditiously and pursued vigorously.
The Need for Monitoring — A ba-
sic requirement for research to gain
a full understanding of the fishery
environmental deterioration of the
Great Lakes is a comprehensive moni-
toring program to measure all aspects
of the chemical, physical, and biologi-
cal environment. The present data
base and existing instrumentation
and techniques are adequate to start
development of a suitable monitoring
system. Data from monitoring are
needed to provide measures of the
long-term trends and the frequency,
intensity, and duration of short-term
fluctuations in environmental factors.
Particular attention should be given
to physical and chemical contami-
nants, and the measurement of
changes in the composition and
biomass of biological components of
the environment. Meaningful moni-
toring will require a full understand-
ing of the sources and identity of all
physical, chemical, and biological
contaminants entering the lake.
Research Questions — Environ-
mental monitoring and the sources
and identity of contaminants will
provide the data that are needed to
give clues for cause-effect relations
that can be investigated by specific
field and laboratory studies. What
factors contribute to failure of hatch-
ing or early survival of the previously
abundant native species that must be
restored? Precisely how might certain
chemicals, such as pesticides and
heavy metals, influence the physiol-
ogy, behavior, reproductive process,
or survival of various species of fish?
What effects would massive releases
of thermal wastes in various locations
and by various methods have on
eggs, fry, young, and adult fish, and
fish-food organisms, in different sea-
sons? These questions must be an-
swered to provide suitable guidelines
for maintaining the biological stabil-
ity and productivity that might be
achieved after the present environ-
mental degradation has been halted
and reversed in the most seriously
affected lakes.
Even under very stringent protec-
tion, the Great Lakes will continue to
be influenced by growing urbaniza-
tion and industrialization within the
drainage. These influences will un-
doubtedly cause some uncontrollable
changes (physical and chemical con-
tamination, directly or indirectly re-
lated to pollution or modification of
the atmosphere) and accelerated en-
richment. Change may continue to
be too rapid for biological processes
to accommodate to it. Thus, research
will be required to determine the rate
of change that can be tolerated and
still maintain biological stability and
fishery productivity in the Great
Lakes. This information will be es-
sential for possible future modifica-
tion of the initial guidelines and
standards that must be enforced im-
mediately to "save" the Great Lakes.
Need for Increased
Understanding and Action
It has been said that, for the
aquatic ecologist, fish are the miner's
canary. The reason why some spe-
cies have disappeared is unknown,
but deterioration of water quality
264
LAKE EUTROPHICATION AND PRODUCTIVITY
that has an adverse influence on fish
may signal a trend that could soon
have detrimental effects on other life
dependent on water, including hu-
mans. Restoration of the Great Lakes
for fish should also restore their value
for all other uses.
The essential measures that must
be taken from the environmental
standpoint to restore the lakes that
have been severely damaged (Erie
and Ontario) and reverse deteriora-
tion of the others (Michigan, Huron,
and Superior) are clear. The attack
must be basin-wide, must be initiated
expeditiously, and pursued vigor-
ously. The plan must include: (a)
improvement of land uses within the
drainages that have direct or indirect
influences on the lakes and their
tributaries; (b) elimination of sources
of physical, chemical, or biological
pollution entering the lakes directly
or indirectly; and (c) restoration of
favorable and productive fish popula-
tions within the lakes.
Restoration of Environmental Con-
ditions — Improvements within the
drainage basin of the Great Lakes
will require extensive restoration of
vegetation and forests that were de-
stroyed by wasteful land practices of
the past century. This will improve
the water quality and increase the
stability of the flow of tributaries
entering the lakes. Land-use prac-
tices, both urban and domestic, must
be modified and closely regulated
to prevent toxic substances (pesti-
cides and others) and fertilizers from
entering the runoff of the drainages.
(See Figure VIII— 15) No practice
should be allowed that would influ-
ence streams or rivers biologically,
physically, or chemically in such a
way that water conditions would be-
come less favorable than those that
might be expected from natural runoff.
The most crucial problem of lake
restoration is the elimination of all
sources and kinds of pollution that
enter the lakes. Any treated effluents
or domestic and industrial wastes that
are permitted to enter the lakes must
be of equal or better quality than
the waters in the lakes they enter.
Effluent from waste treatment that
cannot meet these standards should,
after being treated to the highest
degree possible, be diverted into
drainages outside the Great Lakes
basin. These effluents would be of
higher quality than the water of
rivers into which they would be
diverted; thus, the practice of divert-
ing them from the Great Lakes would
have the dual benefit of preventing
degradation of the Great Lakes and
improving the water flow and quality
in rivers of the north and central
United States.
Costs of water treatment (partic-
ularly for industrial wastes) might be
reduced greatly by the construction
of inland waterways wherever feas-
ible to permit reuse of water and
provide channels for the diversion
of treated waste waters from the
Great Lakes basin. A number of
proposals for the construction of
such channels in the Great Lakes and
central U.S. regions have already
been made. It may, in fact, be neces-
sary to divert excess water from the
Great Lakes region to irrigate the
arid south-central sections of the
United States before the end of this
decade. Present collective drainage-
disposal systems are a move in this
direction; but, unfortunately, they
are not being planned to fit a basin-
wide system and will probably have
to be modified or rebuilt at great
cost before the century ends.
Figure VIII— 15 — THE EFFECT OF FERTILIZER ON
NITRATE CONCENTRATIONS IN RIVERS
80
1 1 1
i
1 1 1 1 1 1 1
• 1945-1950 KASKASKIA
ICKfi-lQfiA K/^KASKIA
1
70
-
O 1945-1950 SKILLET FORK
1946-1961 SKILLET FORK
—
60
-
50
-
40
-
30
-
/-
20
10
n
• • •
i i T
•
O
1
* \ /
^, — - • _^_V* •.
1 1 1 1 1 1 i
- 0\.
U.S. HEALTH
LIMIT
J J
Months
The graph shows the difference in nitrate concentrations between two rivers in
Illinois — the Kaskaskia River, which drains a heavily fertilized farming area, and
the Skillet Fork River, which drains an area where little fertilizer is applied. The
threefold increase in nitrate concentration for the Kaskaskia River between
1945-1950 and 1956-1968 follows the increased use of industrially fixed nitrogen
fertilizers.
265
PART VIII — AQUATIC ECOSYSTEMS
Release of heated waste water into
the Great Lakes should not be per-
mitted until studies have shown that
the previously abundant native spe-
cies will not be adversely affected.
The only fish that can thrive in lakes
the size of the Great Lakes are cold-
water species, and all spend portions
of their life cycle either near the
shore or the surface of the lakes.
Fish in the larval and juvenile life
stages are the ones that usually live
near shore or the surface and would
be most sensitive to the influence
of heat wastes in these regions. Their
presence in these regions would be
mostly during late winter to early
summer, when thermal gradients
would be the sharpest and possibil-
ities of detrimental effects the great-
est.
Restoration of Fish Stocks — Cur-
rent with restoration of more fa-
vorable environmental conditions,
steps must be taken to restore more
favorable stocks. Sea-lamprey control
now being conducted in Lakes Supe-
rior, Michigan, and Huron must be
intensified and extended to Lakes
Ontario and Erie. Measures to reduce
alewives should be intensified by
introduction of large predators such
as lake trout and salmon and by
exploitation where necessary. The
most critical requirement, while re-
ducing alewife populations, is a con-
current restoration of the small native
forage species. This transition will
require several decades and will re-
quire careful measurement and close
regulation of the kinds and amounts
of fish introduced or removed from
the lakes.
Successful restoration of fish in
Lakes Erie and Ontario will require
sufficient improvement of water qual-
ity to permit establishment of pre-
viously abundant species. Control
of sea lampreys and reduction of
alewives in Lake Ontario should re-
verse deterioration of fish stocks as
water quality is improved. Restora-
tion of Lake Erie will require the
development of some method to re-
duce the extreme abundance of
sheepshead in the open lake and carp
in the shallow areas to create condi-
tions favorable for return of more
desirable species.
Present Urgency
The need for immediate action to
restore the environmental quality,
biological stability, and fisheries of
the Great Lakes cannot be stressed
too strongly. At present, Erie and
Ontario are the only lakes that have
been measurably affected by water-
quality deterioration throughout the
entire lakes. One of the largest rivers
in the world — the St. Clair-Detroit
River system — flows through these
lakes, and the water entering this
river system from Lake Huron is still
of high quality. Erie and Ontario are
the smallest of the Great Lakes and
have flushing rates (ratio of lake
volume to volume of annual inflow)
of approximately 3 and 8 years, re-
spectively. Thus, if all wastes are
prevented from entering Lakes Erie
and Ontario, there should be initial
improvement of water quality within
5 to 10 years and significant improve-
ment of water quality and aquatic life
within 20 years.
The most urgent need, however, is
to stop the environmental deteriora-
tion of Lake Michigan. Degradation
of Lake Michigan has approached the
point that biological processes are
being adversely affected. Once dis-
rupted, it may not be possible to re-
store the fishery productivity of Lake
Michigan. Even with complete re-
moval of all wastes from effluents
entering the lake, or diversion of all
effluents from the basin, the water
from natural runoff into Lake Mich-
igan would be richer than water
within the lake. Consequently, Lake
Michigan could not be flushed or
"cleaned." (The only possibility for
flushing Lake Michigan would be
to divert a large quantity of water
from Lake Superior and introduce it
at the southern end of Lake Mich-
igan.) The deterioration of Lake
Michigan would hasten the deteriora-
tion of Lake Huron. If this should
occur, the present source of "clean
water" essential for the restoration
(flushing) of Lakes Erie and Ontario
would be eliminated.
Policy Requirements
The techniques and instrumenta-
tion are available and there is a cadre
of scientific personnel knowledgeable
about the broad biological problems
and requirements for their solution
on the Great Lakes. There is, how-
ever, no U.S. organization with the
specific mission or clear responsibility
to conduct the studies or establish
the guidelines that are necessary to
assure the biological stability or
maintenance of the over-all fishery
productivity of the Great Lakes,
other fresh water, or estuarine wa-
ters of the United States. Also, the
facilities are lacking for necessary
further study. There is also no pro-
vision in the scattered existing moni-
toring systems for the comprehensive
coverage of all physical and chemical
parameters that would be required
for biological studies, and biological
and fishery monitoring are minimal in
some areas and lacking in most areas.
The Great Lakes are a national and
international resource and must be
managed as a complete system.
There is no federal agency or com-
bination thereof that can assume full
U.S. responsibility, nor are there in-
ternational agreements that can guar-
antee full and effective joint interna-
tional action. Of the several agencies
and commissions with responsibilities
concerning the Great Lakes, the
Great Lakes Fishery Laboratory (U.S.
Department of the Interior) and the
Great Lakes Fishery Commission
(U.S. -Canada compact) have the
broadest experience and delegations
of responsibility for studies and the
greatest capacity to make recom-
mendations concerning environmental
quality — particularly concerning
problems related to biological degra-
dation and fishery resources.
266
LAKE EUTROPHICATION AND PRODUCTIVITY
The Great Lakes Fishery Labora-
tory has made evaluations of envi-
ronmental quality and fishery re-
sponses to environmental change ever
since it was established in 1927. Its
present laboratory facility and four
research vessels constitute the great-
est U.S. capability to provide guide-
lines and criteria for Great Lakes
fishery and environmental restora-
tion. At present, however, its efforts
are limited to partial studies on cer-
tain sections of Lakes Superior, Mich-
igan, and Erie, with token attention
to Lakes Huron and Ontario. Resto-
ration of the Great Lakes environ-
ment will require full attention to all
lakes, and will need much more than
the present effort by the Great Lakes
Fishery Laboratory and the fragmen-
tary efforts of other U.S. Federal
water-related agencies that have
smaller capability and less compre-
hensive Great Lakes responsibilities.
The Canadian government has
recognized fully the urgency for ac-
tion on the Great Lakes. It has started
the construction of a federal labora-
tory on Lake Ontario which, when
completed in 1972, will house 250-
300 scientists and will be capable of
surveillance of all water-quality, bi-
ological, and fishery aspects of the
Canadian portion of the Great Lakes.
An even more substantial facility
would be required to meet the full
U.S. commitment on the Great Lakes,
since the United States has 64 per-
cent of the Great Lakes within its
boundary and contributes some 80 to
90 percent of the industrial, urban,
and agricultural contamination enter-
ing the lakes.
Problems of Eutrophication in the Great Lakes
One of today's pressing problems
is to formulate and execute a man-
agement program for the nation's
freshwater resources. These re-
sources are of tremendous value;
they are used for water supply (do-
mestic, industrial, agricultural), rec-
reation, navigation, hydroelectric
power, waste disposal, and food sup-
ply. Only a few of the nation's fresh
waters are used for multiple purposes,
and these few will be short-lived if
present practices are followed. The
underlying cause for this situation is
the use of these waters for waste
disposal, which results in chemical
enrichment, or eutrophication, jeop-
ardizing all other uses and producing
a general deterioration of the human
environment. Therefore, the over-
riding water-resource problem is not
water scarcity but water management
directed toward control of pollutants
at the source and means of ameliorat-
ing the eutrophic effects of existing
polluted waters.
Among the numerous water bodies
in the United States and Canada, the
Great Lakes are the largest in area
and volume and rank as the most
important single water resource in
respect to economic, recreational, and
aesthetic values. They constitute
about 40 percent of the total surface
waters of North America, possess a
drainage basin of 295,000 square
miles in which live nearly 40 percent
of this country's population. Accord-
ing to reliable projections, these lakes
lie in the pathway of the most rapid
industrial and urban development in
the United States and Canada.
Despite their great value, there is
an astonishing lack of fundamental
knowledge about the Great Lakes.
This stems from their great size,
international and national political
fragmentation of their drainage basin,
need for an interdisciplinary approach
to their complex problems, and need
for meaningful, total system studies
of this mesoscale aquatic system.
Furthermore, there has been little
sense of urgency in establishing
management procedures for these wa-
ters because of the misbelief that
this vast quantity of water is capable
of receiving almost unlimited quan-
tities of pollutants without producing
harmful effects. Inland communities
use streams entering the Great Lakes
to transport their waste without real-
izing that the lakes become the even-
tual receptors of this waste. Less is
known about waste assimilation in
lakes, especially large ones, than
streams, but we do know that the
residence time for pollutants is much
greater in lakes. In streams residence
time is on the order of days or weeks,
while in the Great Lakes it is decades
or centuries. It is evident that the
Great Lakes environment is danger-
ously susceptible to pollution because
most avenues of waste disposal in
the drainage basin terminate in these
lakes.
Physically, the Great Lakes drain-
age basin is one system; but politi-
cally it exhibits a pattern of frag-
mentation. This physiographic unit
is shared by eight states in the United
States and two provinces in Canada.
The heads of these political units
can speak only for their respective
units. There is no unified plan or
approach for the management or
utilization of their waters or the
solution of common problems in the
drainage basin. Within the United
States, a dozen or more federal agen-
cies are charged with Great Lakes
missions, each carrying out its mis-
sion commendably but none con-
cerned with the lakes as a complete
system. Superimposed on this pat-
tern are the efforts by each Great
Lakes state to deal with these waters
within the framework of its policies.
Only the International Joint Com-
mission attempts to represent the
international interests of the United
States and Canada; it, too, has a com-
mendable record of accomplishments
but its objectives are limited.
267
PART VIII — AQUATIC ECOSYSTEMS
The Great Lakes Basin Commis-
sion, established in 1967, could pro-
vide a mechanism for initiating re-
gional planning and management.
But although the mechanisms, the
technical and scientific knowledge,
and the manpower and economic
need exist for unified efforts in
pollution abatement, water-resources
management, and regional planning
of the Great Lakes drainage basin,
these efforts are lacking. This fact is
of deep concern, because decisions
are being made and priorities estab-
lished in the absence of a unified or
regional plan or an understanding of
the Great Lakes as a total system.
Status of Great Lakes
Eutrophication
Although eutrophication of the
Great Lakes is a pressing national
problem, it has received little atten-
tion until recently. Our understand-
ing of the processes accounting for
the lakes' aging and eutrophication
(chemical enrichment) is based pri-
marily on studies of small lakes, and
much of this information is not di-
rectly transferable to the Great Lakes
because of scale difference.
In general, aging processes begin
at the time of lake origin and go on
until the lake becomes extinct through
filling, ecological succession, and
eventual transformation into a ter-
restrial habitat. Nature or direction
of aging is controlled by such natural
forces as erosion and deposition,
hydrological and meteorological proc-
esses, chemical enrichment, biological
productivity, and ecological succes-
sion. The time-span of lake existence
may vary from a few decades to
many centuries depending on the
rates of these controlling forces or
processes.
These natural forces, operating in
the absence of man, will produce a
predictable direction and rate of
change for a given ecosystem. But
man, through his activities (cultural
forces), modifies the natural trends
and rates. Therefore, man's major
role in lake aging is that of deter-
mining the rates of change, especially
through chemical enrichment, com-
monly referred to as eutrophication.
The activities of man that con-
tribute significantly to the process of
lake eutrophication are:
1. Discharge of domestic and in-
dustrial wastes into waterways.
2. Land-use practices that result
in runoff carrying silt loads,
fertilizers, farm-animal wastes,
and pesticides.
3. Discharge of waste heat from
nuclear and fossil-fuel power
plants and industrial processes.
4. Discharge of pollutants into the
air, which eventually enter wa-
terways by precipitation and
fallout.
Our limited knowledge of Great
Lakes eutrophication has been de-
rived from a large number of isolated
studies over several decades. There
has been no attempt at a unified,
multidisciplinary study of one lake
or of the total Great Lakes as a sys-
tem. The general trends have been
identified but the mechanisms and
rates are known only qualitatively.
The general status of Great Lakes
eutrophication may be summarized
as follows: Each of the five Great
Lakes has undergone measurable en-
vironmental changes in the past fifty
years. The lakes are now character-
ized by:
1. An increase in chemical con-
tent of water and sediments
(phosphorus, nitrogen, calcium,
sulphate, potassium, and chlo-
rine);
2. An increase in biological pro-
ductivity;
3. A change in species composi-
tion of biota;
4. A decrease in concentration of
dissolved oxygen;
5. A decrease in transparency;
6. Highly polluted conditions in
inshore areas, harbors, and
bays.
Lake Erie is the most advanced
eutrophically because of its shallow-
ness, its southernmost geographic lo-
cation, and its large pollution input
from urban, industrial, and agricul-
tural sources. Lake Ontario ranks
second as a result of its position
furthest downstream in the intercon-
nected system of five lakes and its
large volume of deep water. It, too,
has received heavy pollution inputs
from cities, industries, and agricul-
tural activities. Lake Michigan ranks
third, with conditions in its southern
one-third being similar to those of
Lake Erie; the northern portion is of
high quality, resembling conditions
in Lakes Huron and Superior. The
latter two lakes and the northern
part of Lake Michigan comprise about
90 percent of the total volume of
the Great Lakes; they represent the
last large volume of good-quality
water in the United States.
The data base for the Great Lakes
is poor. It lacks uniformity of qual-
ity, and is sparse or lacking in certain
areas. Much of the usable data have
been collected at irregular times over
a period of fifty years. There are
serious data deficiencies in the follow-
ing areas:
1. Lake circulation, both open-
lake and inshore;
2. Characteristics of thermal bars
that form inshore and isolate
the nutrient-rich river effluents
for periods of several weeks;
3. Quantity, concentration, and
form of chemical inputs from
domestic, industrial, and land
drainage sources;
4. Atmospheric input;
268
LAKE EUTROPHICATION AND PRODUCTIVITY
5. Role of lake sediments in the
cycling and storage of chemical
substances;
6. The precise residence time of
water in each lake basin;
7. Utilization and cycling of nu-
trients by biota;
8. Population dynamics of various
communities;
9. Energy budget;
10. Water budget.
Without more complete information
in these areas, the eutrophication of
the Great Lakes cannot be effectively
controlled.
Importance of Scale in the
Design of Great Lakes Studies
The matter of transferability of
information and experiences derived
from studies of small to large lakes
requires careful evaluation before a
Great Lakes eutrophication program
is established. Although the funda-
mental processes of aquatic systems,
whether large or small, are basically
the same, the mechanisms controlling
these processes and the rates may
vary importantly with water-body
size. In the size-series of water bodies
from small lakes to oceans, the Great
Lakes represent the mesoscale aquatic
system. The lakes are subject to
essentially the same physical, chemi-
cal, biological, meteorological, and
geological conditions as the oceans
and they possess both lacustrine and
oceanic characteristics. Nevertheless,
a direct transfer of information from
small lakes to these large lakes is
difficult for a number of reasons.
Some characteristics that make the
Great Lakes uniquely different from
small lakes are:
1. Visible effects of Coriolis force
on water circulation;
2. Distribution of upwelling and
sinking according to relation-
ship of current streamlines and
the shore;
3. Discrete water masses which
maintain distinct limnological
characteristics;
4. Modifying effect on weather;
5. Large water volume in propor-
tion to area of water surface
and lake bottom;
6. Existence of a wide range of
industrial and urban complexes,
land uses, shore development,
and water uses in the 295,000
square miles of drainage basin;
7. Each of the five lakes differs
in size, morphometry, and lim-
nological characteristics, but
they are interconnected, result-
ing in a flow-through or down-
stream effect;
8. Residence time for water in a
lake basin may exceed 100
years.
Scale, then, becomes an important
factor in designing studies on the
Great Lakes. Two ways to meet some
of the inherent difficulties are: (a)
extrapolation of experience from
small to large lakes, including labo-
ratory-type studies as well as studies
from scale enclosures (plastic bags,
cylinders, etc.) and the experience
gained from intermediate-size lakes;
and (b) development of appropriate
mathematical models (black-box mod-
els, hydrodynamic models, produc-
tivity models, etc.). Transfer from
physical models (small lakes) could be
facilitated by developing some kinds
of transfer coefficients, analogous to
Reynold's numbers.
Plans for Action
It becomes apparent that water-
resource problems of the Great Lakes
are large, diverse, and urgent. There
is general agreement among scien-
tists, engineers, political scientists,
and socio-economists that the most
fruitful approach to the solution of
these problems is a direct study of
the lakes through use of systems-
analysis techniques and a well-de-
signed program of data collection and
analysis. There is also basic agree-
ment that an effective program to
control Great Lakes eutrophication
must place primary emphasis on con-
trolling nutrients and pollutants at
source of entry and secondary em-
phasis on measures to ameliorate the
effects of these substances after en-
tering the lakes.
Modeling Efforts — Several organi-
zations and research teams are devel-
oping a set of linked systems-modeling
studies that will use simulation as a
research tool in conjunction with the
study of the Great Lakes. The long-
range objective of this effort is to
construct a region-wide comprehen-
sive model. Initial efforts are directed
toward a water-quality model on a
regional scale, a water-quality sub-
system model for one or more sub-
regions within the Great Lakes basin,
and a regional economic-growth
model. These efforts are too new to
have produced tangible results, but
this kind of thinking dominates pres-
ent Great Lakes investigations. The
organizations offering leadership in
this approach are: the Great Lakes
Basin Commission, with emphasis on
regional models; the Council on Eco-
nomic Growth, Technology and Pub-
lic Policy of the Committee on In-
stitutional Cooperation (CIC), with
emphasis on water-quantity and
water-quality models; the University
of Michigan Sea Grant Program, with
emphasis on comprehensive modeling
of a subregion (Grand Traverse Bay);
and the University of Wisconsin Sea
Grant Program, with emphasis on
modeling of Green Bay.
Data Collection and Systems Anal-
ysis — Two field-data collection pro-
grams and related systems-analysis
efforts that are under serious con-
sideration will serve as examples of
current thinking on Great Lakes in-
vestigations. The first is a materials-
269
PART VIII — AQUATIC ECOSYSTEMS
balance study of one of the Great
Lakes, preferably Lake Michigan be-
cause it lies entirely within U.S.
boundaries, simplifying operational
logistics and interdisciplinary study,
or Lake Ontario, which is the object
of the International Field Study on
the Great Lakes of the International
Hydrological Program. This would
involve a study measuring the input
from industrial and urban sources,
land drainage, and the atmosphere.
The output would include measure-
ments of loss through outlets, reten-
tion by sediments, removal of biota,
and loss to atmosphere. Other as-
pects of the study would be directed
toward the dispersal of input ma-
terials in the lake by currents and
general water circulation, and the
interaction between input materials
and the biota. The major problem
to be solved by this study is the
assimilation capacity of the lake wa-
ter — that is, the amount of material
it can receive without deterioration
in quality. The object would be to
prevent inputs above the assimilation
capacity, as well as to determine the
costs for maintaining a given water
quality. This would require estab-
lishment of water-use priorities, a
political decision yet to be made.
Also, information on the kinds, quan-
tities, and concentration of materials
entering the lake would make it pos-
sible to evaluate the relative impor-
tance of a pollution source and to
identify the sites where pollution-
control measures would be most ef-
fective. Moreover, it would produce
high-quality information essential for
predictive capabilities (modeling) con-
cerning the nature and rates of eu-
trophication, and it would serve as
a model for studies of the other Great
Lakes.
A large part of the required data
for this materials balance is presently
being collected by several federal and
state agencies and regional univer-
sities conducting investigations on
Lake Michigan and its drainage basin.
Success of this study would require
cooperation among these organiza-
tions. The organizational structures,
personnel, and facilities are in exist-
ence; only a coordinated effort is
needed. Such a study would not
lessen the present need to deal with
urgent local problems by federal and
state agencies, but it would produce
new and exciting possibilities for
attacking pressing Great Lakes prob-
lems on the basis of a total system
and long-term planning.
In the second example, the pro-
posed study would focus on a major
river system, such as the Grand River
in the Lake Michigan basin, aimed
at determining the impact of its dis-
charge on the inshore lake waters
receiving it, and alternative methods
of reducing this impact. A materials
balance of the river and the source
of materials would be determined for
the entire river. The accompanying
systems analysis, among other things,
would determine the benefit/cost im-
plication of maintaining an acceptable
water-quality standard and would
pinpoint alternatives for solving the
local water-resource problems. The
impact of river discharge on the in-
shore area would involve studies of
currents, thermal-bar phenomena,
and biochemical interactions. The
significance of such a study is evident
when it is realized that approximately
90 percent of the pollutants entering
the lakes do so through river systems.
This would serve as a model for at-
tacking the problems of other major
rivers entering the lakes.
Expected Results — These sug-
gested attacks on Great Lakes eu-
trophication would identify rather
specifically: the need for new instru-
mentation such as automatic monitor-
ing devices; the application of remote
sensing methods to water-resource
investigations; the prevailing socio-
economic and political problems; and
the need for an interdisciplinary ef-
fort involving the cooperation of
personnel from universities, industry,
and government. It would also make
possible reasonable estimates of costs
involved in establishing a manage-
ment program for the entire Great
Lakes basin. The high rate of Great
Lakes eutrophication argues for im-
mediate action on the general prob-
lems presented in this discussion.
Pollution and Recovery in Lake Washington
The city of Seattle lies between
Puget Sound and the west side of
Lake Washington. Early in this cen-
tury, the lake was used for disposal
of raw sewage, and unsatisfactory
conditions developed. In the early
1930's, most of the sewage was di-
verted to Puget Sound, and for a few
years the pollution of the lake was
considerably reduced. But Seattle was
expanding and smaller towns around
the lake were growing. In 1941, a
two-stage biological sewage-treatment
plant was established on the lake, and
by 1954 ten such plants had been
built. Another one was built on one
of the inlets to the lake in 1959.
In addition, some of the smaller
streams were heavily contaminated
with drainage from septic tanks.
Studies of the lake in 1933, 1950,
and 1952 showed increases in the
content of algae and nutrients and
decreases in the amount of oxygen in
the deep water during summer.
In 1955, a conspicuous growth of
the alga Oscillatoria rubescens de-
veloped. This event attracted atten-
tion because this species had occurred
270
LAKE EUTROPHICATION AND PRODUCTIVITY
early in the process of deterioration
of a number of European lakes. Thus,
it seemed to be a distinct harbinger
of pollutional deterioration.
Eutrophication — The problem is
that sewage treated ("purified") by
normal processes is relatively rich in
nutrients, especially phosphate. As
a result, when the effluent is put into
a lake, it acts as a plant fertilizer and
stimulates the growth of algae. While
some increase in biological production
may be favorable, overproduction of
algae results in water of low trans-
parency; large quantities of decaying
algae also produce bad odor prob-
lems. In such lakes, dissolved oxygen
may be exhausted from the deep wa-
ter by decomposition, and this elimi-
nates many desirable species of fish
(whitefish, trout, salmon). These con-
ditions interfere with most uses of a
lake — recreational, water supply, and
fisheries. As long as the sewage is
well treated, human health problems
are not dominant, but some individ-
uals are sensitive to algae and develop
skin rashes or nausea when they are
in contact with the lake.
This effect of pollution, often called
eutrophication, is common around
the world. It is well documented by
many studies. Lake Washington was
thus exhibiting perfectly normal be-
havior when its increase in the abun-
dance of algae began.
Public Action — Public concern
over the sewerage situation had been
growing in the entire Seattle metro-
politan area. In 1955, the Mayor of
Seattle appointed a Metropolitan
Problems Advisory Committee to
study sewerage conditions, among
other things. The obvious beginning
of deterioration of Lake Washington
and the rather clear-cut predictions
that could be made about its future
condition gave focus to public con-
cern. At the same time, it was recog-
nized that unsatisfactory conditions
also existed in Puget Sound and that
a broadly based, coordinated program
was necessary.
As a result of the Committee's ac-
tion, a campaign was organized by
public-minded citizens' groups to de-
velop a governmental organization
to handle the problem (Municipality
of Metropolitan Seattle, or "Metro").
An active informational campaign
was carried out, mostly using infor-
mation about the actual deterioration
of Lake Washington and predictions
about its future.
After a certain amount of difficulty,
Metro was passed on the second vote
in 1958. A project of sewage diver-
sion from the lake was started in
1963 and completed in 196S. The
total cost of Metro to date is about
$145 million, of which about $85
million is attributable to the Lake
Washington part of the project.
Results of Diversion of Sewage —
With the first diversion of about a
third of the sewage, deterioration of
Lake Washington slowed, and further
diversions were promptly followed by
more improvement as measured by
increased transparency of the water
and decreased amounts of phos-
phorus and algae. During late sum-
mer of 1969, the deep-water oxygen
conditions were more favorable than
in 1933, phosphate was nearly down
to the concentrations seen in 1950,
and summer transparency was two-
and-a-half times as great as in 1963.
(See Figure VIII-16)
It is important to realize that action
was taken before the lake had de-
teriorated very far, relative to the
well-known problem lakes in Europe
and the Midwest of this country.
The condition of the lake changed
conspicuously enough that there was
no doubt about its reality, but action
was taken early in the process.
Generalizations from the Lake
Washington Experience
It is clear that Lake Washington
responded promptly and sensitively
to both increases and decreases in
nutrient input. Lake Washington
should not be regarded as unusual;
many lakes are similar enough in
their chemical characteristics that
Figure VIII-16 — TRANSPARENCY MEASUREMENTS IN LAKE WASHINGTON
Meters
SECCHI
1-
^---■-
•—- '"" '
1963 "*"•..,
2-
.1970
3 —
4-
/■if A --""
\ \
\ \
/
1 \
\
\
\
1971
1950
5-
MAR 1 APR '
MAY ' JUNE
JULY
1 AUG
SEPT 1 OCT
The graph shows observations of transparency made in Lake Washington from
1950 to 1971. The measurements are made with a Secchi disc, a 20-centimeter
white disc that is lowered into the water until it disappears from view.
271
PART VIII — AQUATIC ECOSYSTEMS
they would respond just as sensi-
tively. These considerations are rel-
evant to making predictions and to
the development of plans for han-
dling the pollution of the Great Lakes
and others that are receiving effluent
or are going to.
If one is going to make a complete
statement about the processes that
control the productivity and abun-
dance of organisms in lakes, he has
to refer to the whole set of environ-
mental variables: nutrients including
(in addition to nitrogen and phos-
phorus) carbon, such micronutrients
as iron, copper, cobalt, and others.
He has to discuss light penetration
into lakes, the kinetics of photosyn-
thesis, and a great many other things.
But to take practical steps to improve
the condition of a particular lake that
has been polluted is another matter.
It is not necessary to recapitulate the
entire history of limnological investi-
gation in that lake. We know a great
deal already, and can make use of
the general knowledge we have de-
veloped from pure limnological re-
search.
A point of particular interest has
to do with the relative importance
of phosphorus (P) and nitrogen (Nj,
a matter about which there has been
some uncertainty. For practical con-
trol, the proposition very often would
be to ask what the effect would be
of removing most of the phosphorus
from the effluent. That is, to simplify
a little, what would be the effect of
heavily enriching with nitrogen? The
answer to this has to lie in the condi-
tion of the receiving water. If the
natural waters, for geological reasons,
are relatively rich in N, so that P is
the primary limiting factor, phos-
phorus enrichment is likely to in-
crease production.
The obvious thing to do is to find
out which element is limiting in
each particular case. A variety of
techniques exist, ranging from bio-
assay with lake-water samples to
which nutrients are added through
analysis of lake water and plankton
for N and P. Some studies have
shown that added P alone was enough
or almost enough to account for the
observed effect of sewage.
Another rather new approach to
this problem of diagnosis shows that
in Lake Washington, before pollu-
tion, nitrate was in excess in the sense
that when phosphate approached zero
during the spring growth of phyto-
plankton, there was a distinct excess
of nitrogen. After pollution with
phosphorus-rich sewage, P was in
excess in 1962. In 1962, then, Lake
Washington might well have re-
sponded to an increase in nitrogen
which would have permitted the
phosphorus to be used up.
This point is easy to get mixed up.
One must keep clear whether one
is talking about the effect of adding
an element or removing it. One does
the first when trying to explain why
a given lake has gone into nuisance
conditions; one does the latter when
thinking about how to improve the
situation by removing something.
In June of 1962, adding phosphorus
to Lake Washington would not have
increased algae because there was
an excess. Removing phosphorus
would have decreased algae.
In the long run P is the more im-
portant element in much of the world.
But there are places where phos-
phorus is relatively rich in the nat-
ural water supplies. Goldman has
proposed, for instance, that Lake
Tahoe would be susceptive to ni-
trogen enrichment. Also, there are
some organisms that seem able to
get along with much less phosphorus
than others.
If all this is correct, then for each
case we have to identify a key ele-
ment, limitation of which would im-
prove the lake. One could theoreti-
cally limit production by eliminating
any essential element, but in fact
there are very few elements that one
can control. The single element that
is most easily removed from effluents
is phosphorus. So the question boils
down to asking whether limiting
phosphorus, either by removal from
sewage or by limiting detergents, will
be enough to make an adequate dif-
ference. This means, too, that one
must find out whether there is enough
P from agricultural drainage into a
given lake to make a difference.
In Lake Washington, phosphorus
has decreased much more than nitro-
gen or carbon dioxide. (Sewage is
relatively much richer in phosphorus
than is the natural water supply to
the lake.) The abundance of algae
has decreased in very close relation
to phosphorus, not in relation to
nitrogen. (See Figure VIII— 17) This
suggests that, in similar lakes, any
limitation on the amount of concen-
trated sources of phosphorus reaching
the lake will be beneficial. That is,
improvement should result in propor-
tion to the removal of concentrated
sources of phosphorus. Large changes
could be made by reducing the phos-
phorus content of detergents. In
some places it may be worthwhile to
install treatment processes to remove
phosphorus from effluent.
This discussion is focused on the
eutrophication problem. Inflow of
toxic wastes (lead, mercury, cyanide,
herbicides, DDT, etc.) was not an
important part of the Lake Washing-
ton problem, but it evidently is a part
of the Lake Erie problem. In every
case of lake deterioration, one should
find out if toxic wastes are important.
Nevertheless, Lake Erie would prob-
ably be measurably improved by lim-
itation of sewage phosphorus. Char-
acterizing Lake Erie as "dead" seems
quite incorrect.
Unsolved Problems
Plenty of interesting problems re-
main in studying the natural mech-
anism of control of productivity and
abundance of organisms in lakes.
In particular, what is the relation
between the rate of input of nutrients
and the productivity of lakes? It is
common to express the annual input
272
LAKE EUTROPHICATION AND PRODUCTIVITY
Figure VIII-17 — MEASUREMENTS OF ALGAE, PHOSPHORUS,
AND NITROGEN IN LAKE WASHINGTON
150
125
100
CD
>
Z 75
50 —
25
CHLOROPHYLL y
&.""
** \
•
•
i *
~~"J?
— •
•**,,
\ ♦
% ♦
A
V '*••
—
/
*
NITROGEN
\ \
i i
PHOSPHATE "*^\
1 1 1 1 1 1
1962 1963
1964
1965 1966
YEARS
1967 1968
1969
The graph shows observations from 1962 to 1969 of the abundance of algae,
and the concentration of phosphates and nitrates. Yearly values are percentages
of the 1963 values of the concentrations.
on an areal basis as kilograms per
hectare or pounds per acre. But this
is an imperfect and even misleading
calculation. Obviously, the effect of
a given input will vary with the
depth and volume of the lake. That
is, a given input will affect a shallow
lake more than a deep one.
Also, this calculation takes no ac-
count of the fact that some of the
influents are much more concentrated
than others. It seems evident that
a very concentrated source relative
to lake water will mix in and raise
the nutrient content of the lake,
while a source with the same con-
centration will merely displace an
equal volume and not make a net
increase. This is why sewage effluent
is so important relative to any normal
ground drainage: it can be 1,000
times as concentrated in phosphorus
as the natural water. One could
double the nutrient input of a lake
either by doubling the rate of inflow
at the same concentration or by
doubling the concentration in the
same inflow. The effects are likely
to be quite different.
Thus, we have to learn how to
deal with the water budget as well
as the nutrient budget, and to cal-
culate the relative effect of influents
of different concentration. From the
general viewpoint of basic "pure
science" limnology, this would im-
prove our understanding of the com-
parative limnology of productivity —
why lake districts tend to have a
certain uniformity and yet why in-
dividual lakes in one region differ
in productivity.
Obviously, improvements in our
understanding of these matters would
be of tremendous practical impor-
tance. In few situations can there
be a clean, clear-cut, total diversion
of sewage as with Lake Washington.
Often one will want to know what
would be the effect of making some
percentage reduction in the phos-
phorus content of sewage, or of di-
verting some fraction of the effluent.
There is also the question of the
effectiveness of agricultural drainage,
which has probably been exaggerated.
Nevertheless, we could find out
whether it would be worthwhile try-
ing to modify agricultural practices
in a watershed.
Conversely, one might want to
make a very precise adjustment of
enrichment to maintain fish produc-
tion at as high a level as possible
without damaging the desired species
or creating algal nuisances.
The problem, then, is to improve
the predictability of limnological con-
ditions, especially the productivity
and abundance of organisms.
Demonstrably, Lake Washington
has permitted a step forward in this
direction, but we have a long way
to go. Progress is more likely to be
made by limnologists working with
very broad questions than by any-
body else working with very specific
and limited questions on a purely
practical basis. Progress will be
faster and better if some more experi-
ments can be carried out with real
lakes. For example, Lake Erie might
be regarded as a prime object for
limnological experimentation.
273
PART IX
TERRESTRIAL
ECOSYSTEMS
1. COMPONENT RELATIONSHIPS
Environmental Design
All living organisms modify their
environment and leave their imprint
on it. This imprint leads to environ-
mental change. The uniqueness of
the human imprint is in its scale and
tempo. Both by accident and by con-
scious intent, man has been and con-
tinues to be engaged in environmental
modifications that are extensive, in-
tensive, and rapid. His interventions
in and manipulations of the processes
of the planetary life-support system
(ecosystem) have produced a set of
complex problems — the problems of
environmental design.
The entire planet has become man's
niche. He is reshaping the world.
The natural ecosystem is being trans-
formed into a human ecosystem. Just
as the development of a natural eco-
system can be characterized by a con-
tinuum of serai stages ranging from
primitive to climax (see Figure IX-1)
so can the transformation of natural
ecosystem to human ecosystem. A
continuum of anthroposeres com-
prises the stages of succession. The
primitive stage includes a collection
of shelters, a discrete cultural tradi-
tion, and hunting and gathering to
support subsistence. The most recent
stage consists of an interlocking web
of subsystems each of which includes
the city, its satellite towns and vil-
lages, a diversity of cultural tradi-
tions, a complex of communication
links to areas of agricultural produc-
tion, pools of wild plant and animal
genes, natural resources, depots for
wastes, and recreational sites. In-
creasingly, man is drawing on the
resources of landscape and allocating
them to the fulfillment of his own
needs and requirements. Perhaps the
climax stage will be the total trans-
formation of the natural ecosystem
to a human ecosystem. As the human
population multiplies, this process of
transformation accelerates. Man in-
tervenes more and more in ecological
Figure IX-1 — SERAL STAGES OF A DECIDUOUS FOREST
MANAGED FOREST
upto20t/ha
BUILDINGS
UNPRODUCTIVE
OF CRYPTOGAMS
FIELDS
5-25 t/ha
This figure is a schematic diagram of the successional sequence in a deciduous
forest. The rectangular areas indicate where man has arrested the successional
sequence to create other systems. The numbers indicate annual dry-matter produc-
tion in metric tons per hectare (1t/ha = 100g/m-). Cryptogams are plants — ferns,
mosses, algae, and the like — which reproduce by spores and do not produce
flowers or seeds.
277
PART IX — TERRESTRIAL ECOSYSTEMS
processes that he does not fully
comprehend.
There are two reasons for the prob-
lems of environmental design. First,
man cannot, with any certainty, now
foretell the consequences of the trans-
formations in which he is engaged.
Second, he cannot yet design alter-
nate processes for his own ecosystem
that will assure his survival.
Some Specifics
In his design of the environment,
man seems to have locked himself
into a course that will bring him to
the climax visualized before he has
developed the knowledge and skills
for managing such a human ecosys-
tem. This is the essence of the prob-
lem. We shall examine briefly a
few aspects in order to gain a per-
spective on the decisions about en-
vironmental design that man must
make in the decades ahead.
Urban Growth — From the view-
point of environmental design, the
city may be conceptualized as an
empirical allocation of the landscape
to accommodate high population den-
sities in functionally effective con-
figurations of structures, spaces, in-
stitutions, and processes. Although
the city gives the appearance of in-
dependent existence, it is inexorably
bound to its surround, for the city is
a specialized consumer of resources.
It is entirely dependent on a continu-
ing inflow of biological and physical-
chemical resources for its very ex-
istence. These resources include
foodstuffs, fuels, and a variety of
raw materials. Its productivity can
be measured in terms of diverse
fabrications.
The city has become the scene of
some intriguing shifts of population.
There is at once an outward migration
of people from the central city to the
suburbs and an inward migration of
people from the country to the city.
To accommodate these flows, urban
sprawl has developed; the central
city, which began to deteriorate, is
being rebuilt to house greater popu-
lation densities; and vast transporta-
tion links have been constructed to
carry workers between residence and
place of work and to relate the city
to its surround. The spread of the
city has consumed large areas of pro-
ductive agricultural land. The shift
of population into high-density areas
has sharpened the dependence of the
city on the remaining agricultural
lands and on the efficiency and effec-
tiveness of the communication links
with that managed landscape.
Monoculture and the Shrinking
Gene Pool — For relatively fewer and
fewer persons to support the growing
dependent populations residing in
high-density areas, the productivity
of agricultural lands must be con-
tinually intensified. High produc-
tivity demands that an increasing
amount of the landscape be trans-
formed from low-producing climax
associations of a diversity of plants
and animals to high-producing mono-
cultures of domesticated plants and
animals bred to provide for human
needs and requirements and for re-
sistance to pathogens and adverse
weather conditions, particularly cold
and drought. To assure that these
managed lands are maintained as
monocultures, they are protected from
invaders by a variety of biocides toxic
to the invaders but not toxic to the
domesticated organisms or the con-
sumers of the produce. Because the
nutrients extracted from the soil by
the domesticates are not recycled but
diverted to the human consumers, the
nutrients must be restored as chemi-
cal fertilizers. To maintain the vigor
and the resistance of the domesti-
cates, they must be continually inbred
with material from appropriate wild
genes.
As the demands upon the land-
scape intensify, its transformation to
managed agricultural systems spreads
and the space that can be allocated to
pools of wild plant and animal genes
shrinks. As the stocks of wild genes
diminish, the opportunity for invigo-
rating the domesticates and for pro-
viding new domesticates is reduced.
Because man's food base is already
rather narrow, an important decision
in environmental design will be how
to provide adequate space for reser-
voirs of wild plant and animal genes.
Conservation and Recycling of Re-
sources — Reservoirs of wild genes
represent only one decision in envi-
ronmental design to conserve natural
resources essential for the human eco-
system. Because of their vital role in
subsistence, steps must be taken to
preserve the quality of lakes, rivers,
estuaries, and zones of oceanic up-
welling so that their biological pro-
ductivity is maintained. Man also
extracts other natural resources from
the landscape. These resources pro-
vide fuel to support his activities and
materials for his fabrications. Be-
cause the supply of these resources
is finite, environmental designers
must plan for their conservation, allo-
cation among competing needs, and
processes whereby essential materials
may be recycled.
Managing feedback in the emerg-
ing human ecosystem is one of the
most complex problems in environ-
mental design. In the natural eco-
system, organic detritus is fed back
into the environment and recycled
into new organic forms. Relatively
little detritus accumulates in the en-
vironment. Man adapted his methods
of managing wastes to the processes
of the natural ecosystem, but the scale
and tempo of waste production have
exceeded the capacity of natural feed-
backs and the toxic nature of the
human detritus has disrupted the
orderly functioning of the organisms
in the ecosystem. Man must now de-
vise innovative processes to manage
the rapidly accumulating detritus of
the human ecosystem.
Because the resources of the land-
scape are limited, the decisions of
environmental design for the alloca-
tion of these resources among com-
peting demands must include the
278
COMPONENT RELATIONSHIPS
principle of multiple use. The most
pressing demand that might best be
handled by this principle stems from
the time man has for leisure. A re-
sponse to population growth is a
shorter work period for each indi-
vidual. As a consequence, there will
be an increase not only in numbers
of persons but also in the time avail-
able to each person for constructively
filling leisure time. Among the ways
of using leisure time is to engage in
any one of a number of outdoor rec-
reational activities. The demand for
this type of leisure outlet is already
mounting and the pressure will not
diminish. Therefore, in designing the
environment it will be necessary to
allocate to recreation a variety of re-
sources that can fill these specific
needs as well as the more general
needs of the human ecosystem.
Quantitative Analysis — The prob-
lems of environmental design are
problems of ecosystems analysis.
Largely through the initiative of sci-
entists associated with the Interna-
tional Biological Program, a beginning
has been made on the comprehensive
and quantitative analysis of ecosys-
tems. (See, for example, Figure IX-2)
In order to be able to guide the
transformation of natural ecosystems
to human ecosystems, detailed quan-
titative knowledge must be available
of the processes and regulations of
the planetary life-support system.
Techniques must be in hand for com-
prehensive surveillance and monitor-
ing of appropriate physical, chemical,
biological, and social indicators. Sim-
ulation models of ecosystems must
be available to study and predict the
outcomes of alternative strategies in
environmental design. In large part,
these expectations can be fulfilled
through analysis of ecosystems.
Criteria for Environmental Quality
— The quality of the environment is
another facet of the problems of en-
vironmental design. As the transfor-
mation from natural to human eco-
system proceeds, it will be necessary
to preserve environmental qualities
essential to the continuing productiv-
ity and vitality of the biosphere and
those adjunctive qualities that insure
the habitability of the environment.
At the same time it will be necessary
to limit the accumulation of wastes
in air, water, and soil and regulate
the use of agricultural chemicals and
food additives so as not to jeopardize
the fitness of the ecosystem. The task
of formulating criteria to serve as
Requirements for Scientific
Activity
Figure IX-2 — A SYSTEMS MODEL FOR A GRASSLAND ECOSYSTEM
Science is on the threshold of real-
istically tackling these problems of
environmental design. At the very
least, the problems can be stated in
broad perspective. That in itself is a
start in the direction of formulating
approaches to their solution.
A-disciplinarity — These problems
are a-disciplinary. That is, they re-
late at once to no particular discipline
yet involve many, perhaps all disci-
plines. The major problems of the
sciences concerned with environment
make meaningless the traditional
boundaries that have separated man's
compartmentalization of knowledge
and methodology. That science is on
the threshold of tackling a-discipli-
nary problems is evidenced by the
increasing use of such phrases as in-
terdisciplinary, multidisciplinary, pan-
disciplinary, and problem-oriented
configurations of diverse specialists.
Apparently, some scientists are ready
to leave their feudal baronies and join
in innovative configurations specifi-
cally focused on solving well-defined
problems, however complex they
may be.
O extrinsic variable
Q intrinsic variable
— * mass /energy transfer
---» controlling influence
j [ \ trophic/functional group of* variables
HERB1V0RY
ATMOSPHERE
6
RUN-OFF
This diagram represents a significant step forward in the conceptual approach to
the study of an ecosystem and has proved invaluable in the design of research,
team organization, and analysis of data. Nonetheless, the level of sophistication
shown here is well below that needed for application in practical problems. The
complexities arising from the several hundred species and several thousand relation-
ships are still overly simplified, as are the interactions of the system with human
intervention. This figure is typical of the general level of modeling in all subfields
of environmental science, and demonstrates the youth of the field.
279
PART IX — TERRESTRIAL ECOSYSTEMS
guidelines for designing environ-
mental quality has only just begun.
In part, information on which to base
these criteria will emerge from the
analysis of ecosystems. However,
more attention must be devoted to
the biology of man, for he is the least
systematically studied organism from
the viewpoints of function and be-
havior.
Leisure Science — In terms of ful-
filling man's needs and requirements,
systematic studies must be under-
taken of what has been called leisure
science. The constructive and re-
warding use of leisure time will be
one of the central problems of en-
vironmental design and scientists
have just begun to look at this prob-
lem area. The gamut of the problems
of leisure includes the physiology,
psychology, and sociology of leisure,
recreational facilities and resources,
and tourism.
Implementation
We have examined the problems of
environmental design in broad per-
spective. We have noted that there
is a readiness on the part of scientists
to become involved in the compre-
hensive and complex tasks that must
be undertaken for the solution of
these problems. In particular, we
have pointed to an emergence of such
studies as ecosystems analysis, cri-
teria of environmental quality, human
biology, and leisure science. What
might be done to implement the study
of the problems of environmental
design?
Because the problems of environ-
mental design are adisciplinary, it
will be necessary to develop institu-
tions wherein problem-oriented con-
figurations of scholars can be brought
together to work effectively and effi-
ciently in teaching and research. The
administration of these institutions is
most important, for being able to
manage adisciplinary work is just as
relevant as knowing how to tackle
problem-oriented studies. It can be
argued, for example, that present-day
crises are just as much managerial
crises as they are environmental ones.
These institutional formulations are
being explored in the federal estab-
lishment, in state governments, and at
colleges and universities. Progress
has been slow because traditional
values and alignments are difficult to
overcome. Innovation creates inse-
curity among established feudal ba-
ronies. Allocation of limited finan-
cial resources between the old and
the new strains both institutional for-
mulations. Because there is a growing
commitment to developing innova-
tive problem-oriented institutions, it
would seem most important that this
commitment be realistically and re-
sponsibly encouraged.
Maintenance of the Biosphere, with Special
Reference to Arid Lands
For centuries, man has been im-
posing unusual stresses on the eco-
systems with which he comes into
contact. Probably no other organism
has so rapidly, and on such a world-
wide scale, forced far-reaching
changes on ecosystems previously in
equilibrium. By removing particular
species of plants, clearing land for
crops, changing the balance between
herbivores and their predators, alter-
ing the patterns of water movement,
or spreading poisons through the
landscape, man has imposed his will
on nature.
But man's will has been short-
sighted. Accustomed in most of the
workaday world to see the results of
his efforts in hours, days, or, at the
most, in the interval from seedtime to
harvest, he has not realized that
ecosystems operate on a time-scale
which, though short by evolutionary
standards, is long by his own. It may
take a generation or a century before
the more far-reaching effects of his
modification of ecosystems become
fully apparent. In order to attain
wisdom in his relations with natural
ecosystems he must, consequently,
develop long-sightedness — he must
find means of predicting what the
effect of his actions will be, not to-
morrow, but next century.
The arid lands constitute a part of
the biosphere that is more vulnerable
than most. The desert areas of the
Near and Middle East stand today
as a lasting reminder of man's ability
to modify — albeit unintentionally —
this part of his environment. It is
only by an attempt to regard eco-
systems as wholes, and to develop an
understanding of their dynamics, that
such dangers can be averted and wise
use of these delicately poised areas
can be assured. To do so requires
a reversal of what has for decades
been the main current of scientific
endeavor.
Analytical vs. Systems Approaches
When man looks at and considers
his surroundings, he feels impelled to
divide them into discrete units which
he can classify and name. His mode
of thought is based on verbalized
categories and is not adapted to con-
tinuous variation and interrelation.
Furthermore, just as giving something
a name may tend to divert attention
from the thing to the name one has
given it, so categorization of one's
surroundings diverts attention from
the real whole to the categories into
which it has been divided.
Science has long been concerned
mainly with these discrete entities
280
COMPONENT RELATIONSHIPS
into which the environment has been
divided — discrete in thought, though
not in reality- And many of these
entities have been so sundered as to
be the subject of separate disciplines
requiring quite different training.
The meteorologist and the entomolo-
gist, the bryologist and the hydrolo-
gist are unlikely to come into contact,
and unlikely to understand one an-
other if they do. Yet weather and
insects, mosses and streams are parts
of a common over-all pattern within
the landscape, and understanding of
each considered in isolation is bound
to be imperfect.
Even within a discipline it has been
usual to narrow the focus, so that one
is looking at a particular organism, a
particular function, a particular organ
or tissue — perhaps the role of sto-
mata in controlling transpiration, the
function of kidney tubules, the en-
zyme systems of glycolysis, or the
mechanism of adsorption of ions on
the surface of clay particles. This
analytical approach in science —
constantly subdividing one's cate-
gories, and getting to know more
and more about less and less — has
had great success. But there is no
doubt that its practitioners have
found it difficult to see the woods for
the trees.
Over the past twenty years a reali-
zation has been growing that this
fragmented attitude is inadequate to
the subject matter of scientific study.
Science is recognizing the need to
try to fit the pieces together again
and return to the complex whole that
is reality. One form of this newly
prominent synthetic effort is what
has become known as systems analy-
sis, involving the application of math-
ematical and computer techniques to
the problem.
Systems Ecology — Systems analy-
sis applied to ecology ("systems ecol-
ogy") views the ecosystem as a whole
and examines processes within it as
they depend on all the other com-
ponents of the ecosystem — meteoro-
logical factors, soil, plants, animals,
and microorganisms. In the analytic
approach, the photosynthetic rate of
a leaf was viewed in isolation as de-
pendent on the radiation impinging
on it, and the temperature and hu-
midity of the air around it. Perhaps
the analytic approach delved even
deeper, and the oxygen exchange of
a chloroplast was viewed as a func-
tion of the radiation of different
wavelengths absorbed by the pig-
ments and the ionic balance of the
protoplasm in which it was embedded.
In systems ecology, in contrast, the
focus is broader, and attention is di-
rected to the gas exchange of the
vegetation as a whole, or perhaps to
each of the populations of different
species of which it is composed;
changes in rate of this process are
considered, not in a simpler system
actually or conceptually isolated, but
in their whole real-world context —
affected by the general meteorology
of the area, by the soil which deter-
mines the supply of water and nutri-
ents to the roots, by the animals
exerting selective defoliation, polli-
nating, or transporting propagules.
In arriving at this overview, sys-
tems ecology may indeed make use
of the results of analytic studies
covering parts of the system. But the
process of synthesis will demonstrate
processes and effects in the ecosystem
that would never have been recog-
nized if the partial processes had been
considered only in isolation.
Systems ecology does not avoid the
need for simplification — ecosystems
are indeed so complex that to think
about them in their full complexity
would be beyond human powers,
even with any conceivable concentra-
tion of mechanical aids. But whereas
the scientific approach of earlier dec-
ades has been by subdivision and
isolation — what one might call a
"vertical" simplification — systems
analysis requires a "horizontal" sim-
plification, in which all major com-
ponents are considered but each is
whittled down to the bare essentials.
Models and Submodels
Generally, the synthesis of partial
processes into a representation of the
ecosystem as a whole is conceived in
terms of a model. The practical proc-
ess of building and testing models is
closely linked with the use of com-
puters, both digital and analogue (or
hybrid) — in fact, it is doubtful
whether this activity would even have
approached its present development
without the availability of computers.
Once a model is built, a computer
program representing it may be writ-
ten, and repeated operation of the
computer program then simulates the
behavior of the ecosystem, as simpli-
fied in the model, under different sets
of conditions. Empirical tests of this
sort can then play a valuable part in
improving the model, even where the
analytical work involved in a direct
approach would daunt a mathemati-
cian. The process of model devel-
opment using computer simulation
consequently has a large "boot-strap-
ping" component.
Development of an ecosystem
model is sometimes based on obser-
vations of the ecosystem as a whole
— changes in quantities within it, or
rate of processes such as the move-
ment of material from one part of it
to another. It may take the form of
a set of differential equations with
coefficients to be estimated, perhaps
subject to constraints. Alternatively,
the model may be divided into a
number of submodels, each of which
can be studied separately and its best
mathematical representation (again in
terms of differential or difference
equations) determined. Figure IX-3
is an example of one such submodel.
The submodels are then combined,
and the performance of the model as
a whole studied.
These two approaches may in fact
arrive at a model of the same struc-
ture, but the estimates of constants
will differ. If they are of the same
structure, the fit to the set of data
used will be better with the first ap-
281
PART IX — TERRESTRIAL ECOSYSTEMS
Figure IX-3 — MOSQUITO SUBMODEL
WATER
WATER
VOLUME
5
EVAP
TEMP
y
HIBER-
NATING
FEMALES
^
*
EGGS
M
LARVAE
-K
Y,
U
PUPAE
-DC
^f
ADULTS
V,
MORTALITY
The figure is a submodel, or subsystem, of the larger desert ecosystem model. This
particular submodel is designed to elucidate how water level and temperature affect
the production of mosquitos in desert playas. Note that water volume is important
initially to the female and the laying of the eggs whereas temperature is important
throughout all stages in the mosquito's life; temperature is also important to the
effectiveness of the water volume.
proach; but these data will them-
selves provide no validation of the
model. In general, however, the de-
velopment of separate submodels as
a first step is likely to lead to a more
sophisticated total model, with greater
variety in its content, than is likely
to be attained by using trial and error
to modify a complete model without
subdivisions. On the other hand, the
possibility that important elements
of interaction between submodels de-
veloped separately may affect their
behavior when brought together is
an ever present danger with this ap-
proach, and must be examined by
validation comparisons of model be-
havior with that of the ecosystem as a
whole.
Data Base — Both approaches to
ecosystem modeling, and modifica-
tions of them, have been explored in
recent years, and various simple mod-
els have been developed for aquatic
and terrestrial systems. Only excep-
tionally, however, have the data been
sufficient even for the construction
of a model, let alone for testing it.
The reason is that the data have
usually been collected earlier, perhaps
for a different purpose, and without
reference to the particular type of
model that was being built. Even
where data were collected with model-
ing requirements in mind, the de-
velopment of the model has often
indicated the need for data additional
to those already collected.
Standard Models — The problem
of modeling does not need to be
tackled afresh and independently for
each new ecosystem that comes under
scrutiny. There is a great deal in
common in the general structure of
relationships within different terres-
trial ecosystems, even as diverse as
tundra and tropical forest, though
none of the species are the same and
the balance of the various life forms
and processes is quite different. Even
between aquatic and terrestrial sys-
tems, there are numerous analogies.
Consequently, it may be expected
that experience in modeling one type
of ecosystem will greatly simplify the
problems when a new type of eco-
system is considered, though all pa-
rameters may have to be estimated
afresh.
Moreover, the value of model de-
velopment is not limited by national
frontiers. Where the same landforms
and biota occur on both sides of a
frontier the same models can be ex-
pected to represent the ecosystems
there, so that a model for the Sonoran
desert in Arizona should also apply
to the Sonoran desert in Mexico.
Even where different biota are in-
volved in different countries, the gen-
eral ecosystem structure as repre-
sented in the model will often be the
same, and only the constants and data
used may need to be changed in order
that the same models should be
applicable.
Terrestrial Systems — In general,
the more successful models have been
concerned with aquatic ecosystems;
they are simpler, with fewer com-
ponents, and limnologists are more
accustomed to recording a wide range
of data than are terrestrial ecolo-
gists. Few terrestrial models cover
more than a limited selection of eco-
system components. In the arid
lands, particularly, it is not possible
to point to any complete ecosystem
model based on well-authenticated
data.
The paucity of models for com-
plete terrestrial systems does not
indicate a similar lack for subsystems.
Certain parts of terrestrial systems
have been the subject of considerable
modeling activity. Some aspects of
meteorology, for instance, are well
served in this way, as is hydrology.
There are models for soil nitrogen
cycling, for photosynthesis and plant
282
COM.XINrNT RELATIONSHIPS
growth, and for predation. Many of
these submodels, however, have only
been claimed to apply in greatly sim-
plified systems, and it remains to be
seen whether they are also relevant
in more complex natural systems.
Uses for Models
As for the use to which models can
be put, it is easier to indicate pos-
sibilities than to point to examples
of their actual use. We will leave
aside uses at the intermediate stages
of the model-building process, where
an imperfect model can itself, by the
development of internal inconsisten-
cies over a long computer run, or by
sensitivity analysis of various param-
eter estimates, point to ways in which
it can be improved. The process of
model building is indeed highly in-
structive, and aids greatly in the de-
velopment of insights into the func-
tioning of ecosystems. Once a model
has been built and validated, though,
it can be used for purposes extrinsic
to its construction.
Experimentation — The model can,
for instance, be used for experimenta-
tion on scales that are impracticable
in real life, and many sources of
error inescapable in the field can
be eliminated. Questions can be
asked and answered, for instance,
on the effects of competition between
species under different meteorological
conditions. Such questions could be
included in a field experiment only by
extending it over different years or
different locations, where extraneous
and irrelevant sources of variation
would be introduced.
Environmental Management —
When the treatments postulated for
the model are such as would be pos-
sible in practice, this use of the model
leads directly to its potential value
as a management tool. The effects of
any proposed manipulation may be
explored far more quickly and cheaply
than would be possible in the field,
and, either by trial and error or by
a formal optimization procedure, a
choice can be made among a number
of possible management strategies,
once goals have been clearly defined.
In the arid lands, for example, the
management goals that might be set
for particular areas could include
prevention of soil erosion by wind
and water; increased runoff of
groundwater recharge; increased (or
maintained) grazing capacity for
domestic livestock; increased num-
bers of wildlife (either for hunters or
as an amenity); and even increased
landscape values, insofar as they can
be defined (good strands of flowering
ephemerals following rain, or good
growth of the more spectacular
plants — Joshua tree, saguaro, palo
verde — might fill this bill).
The practicable management treat-
ments would certainly include dif-
ferent grazing practices (livestock
type, density, and season, together
with methods of stock control);
shrub removal and/or seeding; wild-
life control — by hunting permits,
for example; introduction of exotics
(plants and animals); and perhaps
weather modification. The existence
of a reliable model of the system,
and a convenient computer imple-
mentation, would enable the effects
of any of these proposed treatments
to be evaluated in terms of the
selected goals (appropriately weighted
if multiple); the whole could then
be subjected to benefit/cost analysis.
The arid lands of the United States
are under heavy developmental pres-
sure, which is likely to increase rather
than decrease. The multiple-use con-
cept often applied to them usually
means multiple stresses. Yet manage-
ment, except in limited fields, is per-
force largely intuitive at present.
Development of the management
tools outlined in the previous para-
graphs, accordingly, takes on the look
of urgency where our arid lands are
concerned.
Needed Scientific Activity
We should now examine what are
likely to be the roadblocks restrict-
ing progress in this direction —
where and what sort of scientific
effort will need to be expended to
make these possibilities into realities.
Monitoring — The range of eco-
systems currently being monitored
adequately to provide satisfactory
tests of alternative models is far too
small. It is of the greatest importance
that the ecosystem models produced
should be of high generality, even
though of limited precision; it is far
more valuable to be able to give ten-
tative predictions over a hundred
million acres than to predict accu-
rately the course of events on a
hundred acres. This means that ob-
servational areas against which model
results can be checked must be spread
widely enough, and be numerous
enough, to cover the variation over
which generalization is intended.
Moreover, the establishment of
these monitored ecosystems for the
purpose of validating models under
development should be treated as a
matter of some urgency. Their value
largely depends on the period over
which observations have been made,
for long periods provide the most
exacting test of models. There are
a few sets of data already in exist-
ence — largely collected by the U.S.
Forest Service — extending back for
decades; these are of the greatest
value, even though only a limited
range of variables was monitored.
Field studies for the specific purpose
of validating ecosystem models are
also currently being set up under
the International Biological Program.
(See Figure IX-4) Many more such
sets of data will be needed for the
modeling work that lies ahead, and
in each of them a wide range of
variables should be recorded as a
routine.
Ecosystem Modeling — It would be
premature to try to standardize ap-
proaches to ecosystem modeling. The
subject is not yet ten years old, and
it is far too early to try to put it
into a straitjacket. Several methods
of modeling are presently under test;
283
PART IX — TERRESTRIAL ECOSYSTEMS
Figure IX-4 — A MODEL VALIDATION STUDY
Grams/ m-
40 ■—
36
32
28
24
20
12
4 -
i FIELD DATA
■BHM SIMULATED DATA
160 200
1971— DAYS
The graph shows the output of blue gramagrass biomass in g/m- as simulated by
computer for the growing season of 1971. This simulation is one of the many
outputs of the grasslands ecosystem model. Also plotted on the graph are actual
field measurements of the blue grama production at the Pawnee site. Although
there are differences in the curves, the over-all result indicates that the model is
simulating the actual production. The differences can be explained, at least in part,
by the fact that the abiotic variables that are an input to the model are not measured
at the same location as the sampling point for the blue grama biomass.
they should be given every encour-
agement to develop independently
(though with plenty of opportunities
for contact) for some years to come.
In the meantime, some new approach,
not yet conceived, may well show
itself superior to any.
It is clear that modeling of abiotic
parts of the ecosystem is considerably
in advance of the development of
submodels for the living components.
More effort needs to be given to de-
vising suitable forms for the latter
submodels, and this will probably in-
volve intensive experimental work
on a variety of subjects.
A good deal more thought needs
to be given to the process of validat-
ing models and comparing alterna-
tives. Statistical considerations will
clearly play an important part, but at
present most statisticians avoid the
subject.
Techniques To Incorporate Diver-
sity — Simplification is essential in
the modeling of ecosystems; but the
methods of simplification at present
in vogue (in terms of compartments,
trophic levels, and such) are unlikely
to be the most fruitful. There is little
doubt that the diversity of an eco-
system is an important factor in its
dynamics and stability, and means
must be found to take this diversity
into account in the model. The diver-
sity or heterogeneity that is important
may take various forms; first and
foremost, the division of the biomass
into species, each of which has dis-
tinctive responses to the environ-
ment and, consequently, distinctive
niche requirements; second, variation
within a species of genetic and ac-
quired characteristics, including re-
sponses to external factors and the
timing of vital processes such as
seed germination, metamorphosis,
and reproduction; third, spatial dif-
ferentiation and patterning, partly
dependent on the inanimate substrate,
partly developed through the dy-
namics of the ecosystem itself.
Such heterogeneity has mainly
been incorporated in models by mul-
284
COMPONENT RELATIONSHIPS
tiplying the number of distinct com-
partments recognized; but this proc-
ess cannot be carried very far. Until
some more adequate technique is
devised to deal with the various types
of heterogeneity, the models devel-
oped will be but a pale reflection of
reality.
Computers — Installations at the
disposal of ecosystem modelers are
often rather inadequate for the task.
Modeling teams may be obliged to use
rather slower machines, with limited
storage, whereas ecosystem simula-
tions are bound to be demanding
both of space and time. Programming
and model testing could be greatly
facilitated by a shift from batch
processing to interactive terminals,
which are now available at few cen-
ters.
Digital computers are, in principle,
far from ideal for the simulation of
continuous processes. One would
consequently expect a large hybrid
computer to be appropriate for eco-
system modeling; this may often call
for an alternation of continuous and
discontinuous operations, which could
be performed, respectively, on the
analogue and digital sections of a
hybrid computer. Unfortunately, the
programming of hybrid computers is
at present far more difficult than that
for digital computers, and facilities
for remote-terminal programming do
not exist. Hardware developments to
meet this need are to be hoped for;
in any case, it is important that the
potentialities for ecosystem modeling
of hybrid as well as digital computers
should be fully explored.
Interdisciplinarity — Continued em-
phasis should be placed on the need
for interdisciplinary training. Indi-
viduals brought up within one of
the traditional disciplines, with only
limited and casual contact across the
disciplinary frontiers, can contribute
to a program in systems ecology only
after extensive retraining, formal or
informal. We need personnel with
a broad training in the biological and
earth sciences, who have developed
expertise in certain aspects of mathe-
matics and computer science. This
is made more difficult by the rather
narrow curricula of many universities.
Energy Relationships in Ecological Systems
Energy is essential for life, but
since life itself is dynamic rather than
static, energy flow must occur at all
times. The earth ecosystem functions
because of the flow of energy from
a source, the sun, to a sink, outer
space, after passing through the bio-
sphere. The biosphere, which is that
zone of soil, rock, water, and air
containing organisms, is at an energy
state, or thermodynamic level, that is
compatible with life. This energy
state is neither too warm nor too
cold for life to exist and replicate.
The thermodynamic level of the
biosphere fluctuates greatly, with
both random fluctuations and periodic
cycles. Some portions of the bio-
sphere (polar regions and upper
troposphere or lower stratosphere)
are relatively cold while other por-
tions (tropical regions and thermal
hot springs) are relatively hot. Nev-
ertheless, life has evolved to occupy
all of the earth's surface, some of
the subsurface, and a good deal of
the atmosphere. A part of our under-
standing of the earth ecosystem and
its many subsystems, including spe-
cific biomes (see Figure IX-5), is to
understand the passage of energy
through the various components and
the thermodynamic levels of each and
every part.
However, in order to understand
and interpret the significance of en-
ergy, of energy flow, and of a par-
ticular thermodynamic state in the
context of ecosystem analysis, one
must understand simultaneously the
life processes themselves. Ecology is
that body of knowledge concerning
the relationships between organisms
and environment, organisms interact-
ing with one another, and including
the effect of man on the ecosystem.
Ecosystems are those finite entities of
the landscape which include the or-
ganisms and the physical environ-
ment. One must understand the
physiological and biochemical re-
quirements of each species in the
ecosystem with respect to tempera-
ture, energy, and such effects as
photoperiodism, phototropism, and
the like. The thermodynamic status
of a plant or animal can be appre-
ciated only in the context of its
particular and specific physiological
requirements.
Life-Support Systems
Primary productivity in the earth
ecosystem is the result of photosyn-
thesis. Each and every species of
plant responds uniquely to environ-
mental conditions — to the energy
status, to gas concentrations of the
atmosphere and water, to pollution,
to disease, and so on. The entire food
chain, web, or pyramid begins with
primary production. A "natural" eco-
system has many species of plants,
each collaborating with the others
to produce the total primary produc-
tion of the system but each respond-
ing in a special way to the variable
conditions. Herbivores consume the
plants and each herbivore responds
to the variable energy status of the
ecosystem in a unique way. Each
species of herbivore will have its
own physiological requirements and
biochemical responses to temperature,
light, moisture, gas exchange, pol-
lution, and so forth. Energy is trans-
285
PART IX — TERRESTRIAL ECOSYSTEMS
Figure IX-5 — MAJOR WORLD BIOMES
I Tundra
| Northern coniferous (Taiga),
Temperate deciduous. and rain forest
[>>i£] Temperate grassland
[ 1 Chaparral and Desert
§ Tropical ram, deciduous, and scrub forest
Tropical grassland and savanna, and
Mountains (complex zonation)
This map shows the distribution and location of the world's major biomes. Note that
except in the rugged mountainous regions of North and South America, the distribu-
tion of biome types tends to be along parallels of latitude. Such a situation suggests
the importance of temperature and rainfall, both of which are strongly dependent on
latitude. Studies of past climates and biome distributions also support this concept.
ferred from primary producers to
secondary producers, but the re-
sponse of each herbivore depends on
the daily and seasonal cycles of tem-
perature, light, moisture, gas con-
centration, and such. Carnivores and
omnivores consume herbivores and
primary producers to form higher
levels in the food chain (see Figure
IX-6), but again it should be empha-
sized that each and every species
responds in a unique manner to the
energy state of the system and to
cycles and fluctuations of energy, gas,
minerals, moisture, and the like.
Man is now affecting the life-
support system of the planet earth
to a serious degree. Man is consum-
ing oxygen at a rate that may some-
day change the concentration of this
gas in the atmosphere, and at the
same time man is affecting the pri-
mary source of oxygen production
through pollution and other means.
Man is emitting to the atmosphere
massive amounts of carbon dioxide
(CO-); these directly affect plant
productivity, since increased CO- in
the atmosphere implies increased
rates of photosynthesis. The in-
creased atmospheric CO2 concentra-
tions also imply potential changes of
climate.
The living, green, photosynthesiz-
ing surface of the earth, with all its
associated organisms, has evolved in
synergism with the atmosphere. Each
286
COMPONENT RELATIONSHIPS
Figure IX-6 — PLANT-MOUSE-WEASEL CHAIN
SUNLIGHT
47.1 x 10*
46.5x10" -*
GRASSLAND
Grass Production
Mouse Consumption
Mouse Production
>,170 - — 1,350 Import
Mouse Population Increases 1,569
WEASELS
Weasel consumption
Weasel Population Increase 117
Decomposer Respiration
Decomposer Production
The diagram illustrates an actual energy-flow budget for a plant-meadow mouse-
weasel food chain in an old-field habitat. Numerical values are in kilocalories per
hectare. About 1 percent of the incoming solar energy is converted into plant tissue.
Most of energy represented by this plant tissue is accounted for by respiration and
decomposition. Of the remaining energy, the meadow mice consume only 2 percent.
The weasels, in turn, utilize 30 percent of the available mouse biomass. Of the
energy consumed in each stage of the food chain, the plants use 15 percent in
respiration, the mice 68 percent, and the weasels 93 percent. This supports the
suggestion that successive stages in food chains exhibit an increased utilization of
the energy taken up. However, in this particular food chain, so little of the energy
entering the system was eventually utilized in the conversion of weasel flesh that it
would have been impossible for the habitat to support a secondary carnivore preying
upon the weasels. Because of this tapering off of available energy in a food chain,
food chains rarely exceed five steps and commonly have less.
depends upon the other. The present
composition of the atmosphere is the
direct result of life on the surface,
and life itself depends on the par-
ticular character of the atmosphere.
Ozone in the stratosphere, which
screens the surface from the actinic
ultraviolet rays of the sun, is a direct
photochemical product of the oxygen
that comes from plants. Carbon di-
oxide and water vapor absorb and
emit infrared radiation, thereby di-
rectly affecting the heat balance of
the earth, but these chemical con-
stituents interact intimately with the
green photosynthesizing surface. The
atmosphere has a narrow semi-
transparent spectral window that al-
lows sunlight to flow to the earth's
surface and some radiant heat to flow
to space.
It is this delicately balanced, unique
system of life and atmosphere, in
cooperation with the oceans of the
world, which is the life-support sys-
tem for man. Yet man persists in
dirtying the atmospheric window and
tampering with the energy flow, gas
exchange, and life-support system
itself.
Energy Relations of Plants
Energy exchange for plants is by
processes of radiation, convection,
transpiration, and photosynthesis. We
now have excellent theoretical, math-
ematical models to describe how a
particular plant leaf is coupled to the
climate surrounding it by means of
energy exchange. The plant leaf will
assume a particular temperature and
a particular transpiration rate (the
two dependent variables) as a func-
tion of the total amount of radiation
absorbed by the leaf, air temperature,
wind speed, and relative humidity of
the air (the four independent vari-
ables). The plant's dependent vari-
ables are coupled to the environ-
mental independent variables by the
absorptivity of the leaf to radiation,
the size, shape, and structure of the
leaf, and the internal resistance of
the stomates to diffusion of water
287
PART IX — TERRESTRIAL ECOSYSTEMS
vapor. We understand these matters
well but still need much additional
work in this area. It is the energy
exchange for a leaf which drives all
other processes critical to the life
of the plant.
The next part of the process, the
gas exchange of carbon dioxide and
oxygen release, is not well worked
out. The chemical kinetics of photo-
synthesis and respiration are rate
processes which depend on light,
temperature, and gas concentration
and which are driven by the avail-
able energy. In order to understand
plant adaptation and response to cli-
mate and environment, we must un-
derstand the entire process of energy
exchange, gas flow, photochemistry,
thermochemistry, and physiological
reaction.
Each species of plant has a bio-
chemical response which is enzyme-
controlled. Some plants photosyn-
thesize well at low temperatures and
some at high temperatures, some at
low light levels and some at high
light levels, and so on. More knowl-
edge is needed immediately concern-
ing these enzyme-mediated processes.
Schemes are needed to determine the
basic biochemical response functions
of chloroplasts and mitochondria
within whole leaves as a function of
leaf temperature, light intensity, and
concentrations of oxygen and carbon
dioxide. These measurements must
be separated from the whole process
which involves gas diffusion and the
physical environment.
The matter of photorespiration,
which occurs in most plants, must be
understood much better. We want to
know precisely how it is that net
photosynthesis productivity depends
on the climate conditions of radiation,
air temperature, wind speed, and hu-
midity for each specific kind of plant.
Only now are we putting together
a complete model that incorporates
in a self-consistent manner energy
flow, gas diffusion, leaf morphology,
anatomy, physiology, and biochem-
istry. Such a model is essential if we
are to understand primary produc-
tivity, including the exchange of ox-
ygen, carbon dioxide, water vapor,
and other gases including pollutants.
This is not only important for our
understanding of ecosystems but also
for our management of crops for food
production.
Energy Relations of Animals
The energy budget of specific an-
imals has been worked out for the
first time only in recent years. From
the particular properties of a specific
animal we are able to predict the
climate within which the animals
must live in order to survive. Con-
versely, for a given set of climatic
conditions we can predict the met-
abolic rate required for survival and
this in turn puts limits on the avail-
able food supply. Earlier work con-
cerning the response of an animal
to climate was highly qualitative and
descriptive. (See Figure IX-7) Al-
though useful, this is not sufficient,
since we are dealing with an extremely
complex response to a multiple set
of variables all of which act simul-
taneously.
Our lack of good physiological
knowledge for any particular animal
is likely to be enormous. Informa-
tion concerning metabolic rates, res-
piratory moisture loss, evaporative
water loss, and thermal insulation of
animals is usually poor and inade-
quate. This information is essential
to an understanding of the energy
balance of animals and their specific
response to climate and environment.
Figure IX-7 — ENERGY BUDGET OF A HORSE
> INFRARED THERMAL RADIATION
FROM GROUND
The diagram depicts, simply and qualitatively, the multiple energy inputs and outputs
that affect a horse. Although not quantified in the diagram, it is possible to describe
each input mathematically so that the energy balance of the animal can be com-
puted. The result can be used further as a part of a larger model describing the
energy balance in a field or pasture where grazing takes place.
288
COMPONENT !■ \SHIPS
Yet the ecosystem functions in the
way it does because of the specific
response of each and every animal in
the ecosystem, the totality of which
represents the food pyramid or web
of life. Understanding of these mat-
ters is critical to our understanding
of climate and its effect on plant and
animal communities of the world.
Greatly improved physiological
measurements of metabolic rates and
water-loss rates as a function of
environmental conditions are needed.
It is necessary to know the values
of radiation absorbed by the animal,
air temperature, wind speed, and hu-
midity during the course of any
measurements. The conditions under
which the animal was conditioned
must be specified. In the laboratory,
it would be particularly important
that complete energy-budget analyses
be done for each set of observations
of the animal. In the field, careful
observations are needed of metabolic
rates and water-loss rates as well as
of the microclimate conditions near
the animal. These measurements are
difficult to make, but must be done
and can be done with the aid of
telemetry and other modern methods.
Systems Analysis
On the one hand, mathematical
analysis of the productivity of in-
dividual plant leaves is now being
done based on a holistic approach
including the use of physics, chem-
istry, physiology, and biochemistry.
On the other, agronomists are work-
ing out the energy and gas exchange
of a community of simple plants —
e.g., corn, wheat, or millet. A great
deal of work is required to bridge
the gap between these two ap-
proaches. A given species has leaves
that may occupy various parts of a
plant canopy. The leaves forming
one part of a canopy are in an en-
tirely different microclimate than the
leaves of another part, and the prop-
erties of shade leaves are different
from the properties of sun leaves of
the same species. One can evaluate
the individual leaves of each part of
a canopy, apply the numbers game
for all the leaves of a part of the
canopy, and integrate over the entire
canopy for productivity, respiration,
total water use, and so on. This ap-
proach will match up eventually with
the approach of the agronomist to
the problem of evaluating the whole
stand. However, since the ecologist
is interested in the role of various
species within a stand, it is necessary
to take this detailed approach.
Competition and Phenology — The
ecologist is interested in competition
among the species of a plant commu-
nity — competition for light, mois-
ture, carbon dioxide, and nutrients,
and maybe for wind and air flow,
soil bacteria, and other factors. In
order to understand competition one
must understand the plant response
to energy and gas exchange as they
affect growth, flowering, seed devel-
opment, and so on. A closely related
topic is phenology — the response of
organisms to time-cycles of climate.
To understand phenology we need
to understand the temperature of a
plant as it responds to the climate
of soil and air and to realize the
significance of events throughout the
season that may integrate into plant
response. Studies of competition and
phenology require good laboratory
measurements and good field meas-
urements. It is not so necessary to
obtain an abundance of field data,
however, as it is to analyze well and
completely the field data obtained.
Prediction — As we understand the
specific response of animals to energy
flow (radiation, convection, conduc-
tion, evaporation, and metabolism),
we can begin to work out the re-
sponse of a set of organisms within
a community. (See Figure IX-8) It is
not sufficient to know the amount of
energy transferred through the food
pyramid from primary producer to
primary, secondary, and tertiary con-
sumers; it is also important to under-
stand the energetics of each organism
in the community and the response of
each organism to all climate and
edaphic factors. Furthermore, be-
havioral studies of some animal pop-
ulations often ignore or treat only
cursorily the detailed environmental
conditions. Animal behavior will of-
ten respond to energy flow, as well
as to other factors, in an intimate
fashion.
Despite an acute shortage of good
physiological data for most animals,
we can begin to simulate on the com-
puter communities of plants and an-
imals and their response to climate.
We can set up simple experimental
ecosystems in the laboratory or out-
of-doors and check prediction from
a model against observation. We
need much better evaluations of en-
ergy flow through various ecosys-
tems, as well as evaluations of gas
exchange and nutrient flow. The
biome studies of the International
Biological Program will add consider-
able knowledge, but much remains
to be done.
Modern science has the capacity to
do a much better job of analyzing
energy flow through ecosystems and
evaluating specific physiological re-
sponse. Here is a magnificent oppor-
tunity for a strong theoretical dis-
cipline to be developed. It must be
based on good physiological data
from the plant and animal sciences.
Theoretical development must be
constantly checked by field observa-
tions.
289
PART IX — TERRESTRIAL ECOSYSTEMS
Figure IX-8 — RELATION BETWEEN FOOD INTAKE AND CALORIFIC
EQUIVALENCE OF INVERTEBRATES
Q
O
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LUMBRICIDAE ^^T
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5
ARANEA
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ISOPODA •
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ISOPODA • t^
► ORTHOPTERA
ICHYTRAEIDAE
SOPODA «.^
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P ACARIN
2
10 >
vr
•
V\G
ARINA
io-=
10-'
10" 2 5 10' 2 5
log CALORIFIC EQUIVALENCE (cal indiv ')
10=
The graph shows the relationship between food intake and calorific or heat equiva-
lence of several invertebrates. This information was obtained from published
material and synthesized to determine the mathematical relationship which then can
be used in a numerical, computerized model to predict the amount of heat that is
produced by a given amount of food.
290
A Note on Soil Studies
COMPONFXT RLLATIONSHIPS
Soil science in the United States
is now scientifically stronger than
ever before. Virtually each branch
of the field is staffed with a sizable
number of fundamentalists whose
contributions are adding materially
to an understanding of the soil sys-
tem. Primary direction has been to-
ward agricultural production, and
results have been impressive. Labora-
tories are generally well equipped
with the most modern instruments.
However, with each step toward
increased specialization, we have
fewer and fewer investigators who
are capable of understanding in depth
the entire soil system. Thus, we are
developing more and more specialists
working in highly technical corners
with fewer and fewer investigators
comprehending soils from the stand-
point of the "field effect." Of course,
this problem is not unique to soil
science.
Status and Needs
In examining global soil resources,
we find the subject fairly well docu-
mented in the United States, Europe,
the western sectors of the Soviet
Union, and Australia. Through vari-
ous international organizations we
are getting a more complete picture
of soil resources in other locations,
such as Africa and South America;
but even on these continents the
picture is understood in at least gen-
eral terms. Climate-wise, soil re-
sources in the tropics, deserts, and
the polar regions are not too well
known. Strengthening the former
two is more critical than the third,
since congestion in the temperate
climates is likely to bring increased
population first to the desert sectors
and then to the tropics, and only last,
if needed, the polar regions.
Water Quality and Quantity —
Since water supply and water quality
are of great importance not only for
agriculture but for all of mankind,
the major problem concerns the des-
ert or desert-like areas. Water quality
as well as quantity is related to cli-
mate, substrate, soil, plants, and so
on. The more arid the climate, the
more acute the problem of quantity
and natural quality of water. For
example, drainage waters from desert
areas are more likely to be charged
with excessive salts for irrigation.
Pollution and Soils — In the more
densely populated areas (e.g., east-
ern North America and Europe), the
pollution problem is becoming acute.
When potential pollutants enter the
soil — whether they be industrial
wastes, fertilizers, insecticides, or
detergents, among others — we know
very little of how they react. More
emphasis should be directed to the
study of organic matter, types of
minerals, aeration, acidity, and so on,
to learn how they affect the fate of
potential pollutants. Stronger studies
are needed on persistence adsorption,
translocation, solution, and precipita-
tion of potential pollutants in soils.
If there is one area in which a team
approach is needed, it is on the prob-
lem of ecology and pollution.
Wet Soil Areas — Since most po-
tential pollutants entering the soil
eventually find their way, in one form
or another, to water courses, lakes,
estuaries, coastal sectors, and the
like, these locations are all materially
affected. There are few soil and
substrate studies being conducted in
these critical low areas. Traditionally.
our soils effort has been confined to
farming areas and the growing of
crops. Certainly, the problem of the
soil system in low, wet areas and in
the vicinity of lakes and shores needs
to be strengthened. Soil classification
in wet soil areas is weak; in general,
little attention has been paid to these
areas.
Need for Balance
Soil scientists are not now being
used to full advantage in the United
States. Virtually all ecological and
environmental studies involve the
soil system in some way. The soil
is the link between the organic and
inorganic worlds. But we see vir-
tually all important soil research in
this country being carried out under
the aegis of agriculture, while soil
studies dealing with ecosystems, a
field currently as critical or more
critical than agriculture, are poorly
organized and poorly staffed.
If we are going to master the
pollution problems and problems of
ecology and environmental control,
then there must be a strengthening
of undergraduate and graduate pro-
grams in the subject of soil science
in non-agriculturally oriented in-
stitutions. Soil science should be
programed — as are geology, hydrol-
ogy, climatology, botany, and zool-
ogy — as one of the natural sciences.
It is not implied that the agricultural
effort should be weakened; rather,
the non-agricultural viewpoint should
be strengthened.
291
PART IX — TERRESTRIAL ECOSYSTEMS
2. FOREST ECOSYSTEMS
The Forest As An Ecosystem
A forest is a natural or artificial
vegetation unit encompassing many
different tree associations and harbor-
ing a multitude of other life forms
which use it for food or shelter or
both. Man has used the forest since
his ascent to a dominant position,
either for direct products or indirectly
by destroying large areas and con-
verting the land to other uses —
mainly food production or urban de-
velopment. Currently men consider
forests and forest areas useful for
the following purposes: wood and
fiber production; forage production;
water production; aesthetic values —
with the many ramifications of this
subject. In many instances, attempts
to convert forests to other land uses
have proved unwise, and large areas
have gradually reverted to forest use
or have been converted by planting
of tree species; the species used were
often different from the endemic
populations and, therefore, the forest
ecology has changed.
Generalized Description of Forest
A forest is best regarded as a
system. As such, it is composed of
subsystems, which can be defined in
various ways, depending on the sub-
ject under discussion. Here we prefer
to consider two principal subsystems:
(a) the abiotic, consisting of the non-
living components of the soil on
which trees and other green plants
grow, the atmosphere surrounding
and interacting with the living mem-
bers of the system, and water and
nutrient elements, which are in con-
tinual movement through both biotic
and other abiotic parts of the forest
system; and (b) the biotic subsystem,
consisting of living plants and an-
imals.
Trees are the dominant biotic fea-
ture of forest ecosystems, constitute
the framework of any structure it
may possess, and affect importantly
nearly all other components, biotic
and abiotic. Shrubs, herbs, and non-
vascular plants such as fungi, algae,
mosses, and liverworts make up a
smaller proportion of the total bio-
mass of the forest system but play
vitally significant roles in its dy-
namics. Fungi and bacteria, for ex-
ample, are the principal agents of
decomposition, and all known tree
roots function in symbiosis with my-
corrhizal fungi in the uptake of water
and nutrient elements. Insects, mam-
mals, birds, and other animals are
primary consumers of vegetational
biomass manufactured by trees and
other primary producers and, hence,
affect the functioning of the system
importantly; their numbers are af-
fected by numerous predators and
parasites.
Where Science Stands Today
To a large degree we are still in
the descriptive stage of forest-eco-
system understanding and, in some
instances, not very far along in this
stage. Most of the higher plants have
been described and catalogued for
most forests of the world. However,
a multitude of other life forms exist
and large numbers have not been
identified; certainly their function is
not understood, except for such com-
mon forms as earthworms.
The multiplicity of life forms exist-
ing in forest soils is an example
of the deficiency in our knowledge.
As a more definitive case, if one
looks at a tropical forest in detail
one soon discovers that major spe-
cies have been identified by indus-
trious plant explorers but that our
knowledge largely ceases at that
point. Information on detailed inter-
relationships, even those necessary
to manage and predict the effects
of common manipulations, is largely
nonexistent in the case of tropical
forests.
For forests of temperate regions,
which for the most part have been
studied more by man and on the
whole used more intensively, we
presumably have better information.
The complexity of our problems in
these forests is reduced because spe-
cies composition is simpler, especially
as it relates to the dominant species.
Thus, a northern coniferous forest
may be almost a single-species forest
whereas several hundred tree species
may be found in a few square kilo-
meters in many tropical forests. It
is doubtful, however, that the same
simplicity applies to all other life
forms.
In many instances, man has man-
aged temperate and boreal forests
rather intensively for relatively long
periods of time to various ends —
principally the production of wood.
It is not surprising, therefore, that
a considerable body of information
has been built up relating to growth
rates of certain important species in
a given environment. In such cases,
much is also known about the man-
agement of water resources or the
provision of forage for wild or do-
mestic animals, and we have fre-
quently acquired considerable prac-
tical information on forest insect
populations and diseases.
Despite the relatively large amount
of work on forests, the conclusions
seem justified that much of it has
been descriptive, on relatively small
areas of a large forest resource, and
so far has not materially enhanced
our ability to make accurate predic-
tions of important processes occur-
292
FOREST ECOSYSTEMS
ring in forest ecosystems. For in-
stance, we have no certain road to
regeneration of a forest after natural
or artificial removal, and many of
the problems that develop in man-
agement are still unpredictable.
What We Need to Know
An appraisal of present knowledge
about forest ecosystems leads to the
conclusion that we need to know
more about the following subjects
in order to understand these systems
more thoroughly and make reason-
ably accurate predictions.
1. Details of many life forms
other than trees, especially
those using the soils as a hab-
itat;
2. Competitive aspects of forest
life;
3. Dynamics of forest popula-
tions;
4. Stability of forest environ-
ments;
5. Forest growth and forest en-
vironmental relationships;
6. Potential utility of different
kinds of biomass produced in
forests;
7. Total productive capability of
forests with improvements man
can add;
8. Aesthetic management of for-
ests;
9. Method of coordinating and in-
tegrating information collected
on forests to answer some of
the above questions and pre-
dict results of forest changes —
in other words, some kind
of workable forest-ecosystem
model.
In a broad sense, lands devoted
to various forest uses are considered
to be within public control even
though operated by private individ-
uals. This seems to be particularly
true of relatively large ownership, in
contrast to the small acreages gen-
erally referred to as farm woodlots.
For example, game, fish, and recrea-
tion are considered to be public goods
on these private lands and, therefore,
subject to some public control and
management. In addition, of course,
the United States is blessed with large
areas of public forest land, managed
by various agencies for a variety of
purposes.
In assessing the question of how
research can do more for the public
good in the management of these
lands, we should probabl . look first
at the purposes for which the land
is to be used and the public good
to be served. If a real public need
is paper for education, or building
material to improve housing of a
large segment of the people, then one
can make a logical argument for
developing research programs that
would make at least some of our
forest ecosystems as productive in
wood fiber as possible.
On the other hand, if the best
public need is served by setting aside
most of the areas for recreational
purposes, then we must develop pro-
grams that would enable these lands
to be used by large numbers of
people but still maintain the recrea-
tional and aesthetic aspect of the
forest ecosystem. This is a more
difficult task than most people realize
and one which has had little investi-
gation. For some reason, we have
assumed that describing an area as
a National Park or a Wilderness sets
it up for permanent maintenance of
its original state without undue prob-
lems. In one sense, the problems
imposed by large numbers of people
on delicate forest ecosystems are
more difficult to predict than uses
for wood or water. Therefore, we
must know enough about our forest
ecosystems to set up the proper public
use and then develop the information
to manage them for that purpose.
A Note on Hubbard Brook
The study of interrelationships of
forests, water, and minerals requires
a special study vehicle that allows
integration of information from sev-
eral separate fields. As of now, re-
search levels in the separate fields
of forest soils and hydrology are
reasonably adequate. Many forestry
and conservation schools and federal
and state agencies maintain person-
nel and research facilities suitable
to the study of these separate fields.
But truly integrative research, which
welds the expertise of various dis-
ciplines and focuses it on a particular
ecosystem, is relatively rare.
The Hubbard Brook Study
The Hubbard Brook Ecosystem
Study was conceived and developed
as a multidisciplinary study of single,
well-defined watershed ecosystems,
including both natural and man-
manipulated ecosystems. The Hub-
bard Brook Experimental Forest com-
prises about 7,500 acres in the White
Mountains of central New Hamp-
shire, operated and maintained by
the Northeastern Forest Experiment
Station of the U.S. Forest Service.
It is surrounded by a large, undis-
turbed tract of the White Mountain
National Forest, which consists of
a series of discrete watersheds with
similar northern-hardwood forest
vegetation and a homogeneous bed-
rock that forms an impermeable base.
293
PART IX — TERRESTRIAL ECOSYSTEMS
The original goals of the Hubbard
Brook Ecosystem Study were to un-
derstand the energy and biogeochem-
ical relationships of northern-hard-
wood forest watershed ecosystems as
completely as possible in order to
propose sound land management pro-
cedures. A small-watershed ecosys-
tem approach was used to study
hydrologic cycle-nutrient cycle inter-
action in forest-stream-lake ecosys-
tems. This concept provided an
opportunity to deal with the complex
problems of the ecosystem on an
experimental basis.
Integrated ecological studies of
these small, watertight, replicated for-
ested watersheds were begun in 1963
by Likens and Bormann in coop-
eration with the U.S. Forest Service.
The study has involved some 32
senior scientists from ten universities,
one national laboratory, and three
government agencies. The specific
work ranges from studies of complete
nutrient budgets, including measure-
ments of inputs of cations and anions
in precipitation and losses of cations
and anions in dissolved and particu-
late matter exiting the system, to
studies of nutrient cycle-hydrologic
cycle interactions, weathering rates,
soils, litter accumulation and degrada-
tion, biomass measurements, produc-
tivity, nutrient turnover within the
biota, phenology, energy pathways
and relationships, and experimental
manipulation (deforestation) of an
entire watershed ecosystem. Figure
IX-9 illustrates the results of one
such study. In addition, a biogeo-
chemical study of a small lake within
the general drainage area of Hubbard
Brook is under way. Computer simu-
lation and systems-analysis proce-
dures are being developed to facilitate
understanding of the complex inter-
relationship of these ecosystems.
The results of the study to date
have been described in numerous
publications. The project has been
endorsed by the U.S. National Com-
mittee for the International Biological
Program (IBP), and the study has
been accepted as a part of the U.S.
Figure IX-9 — ECOLOGICAL EFFECTS OF DEFORESTATION
TRANSPIRATION
REDUCED 100%
EVAPOTRANSPIRA-
TION 0.3X
COMPLETE CUTTING
AND HERBICIDE
REPRESSION OF
NEW GROWTH
VELOCITY OF
STREAM DISCHARGE
UP, VISCOSITY OF
STREAMWATER
DOWN IN SUMMER
RELEASE FROM INHIBITION
BY VEGETATION?
MICROCLIMATE
WARMER, SOIL
MOISTURE HIGHER
IN SUMMER
BIOTIC REGULATION
OF EROSION AND
TRANSPORTATION
REDUCED
OUTPUT OF STREAM-
WATER 1.4X
MOSTLY IN SUMMER
ORGANIC MATTER
TURNOVER ACCELERATED
NITRIFICATION
INCREASED 2.5X->100X
ACIDIFICATION OF
CATION EXCHANGE
SITES
CATIONS
CATIONS
ANIONS
CONCENTRATION OF
DISSOLVED INORGANIC
SUBSTANCES IN
STREAMWATER 4 IX
OUTPUT OF
PARTICULATE
MATTER
ca. 4.0X
I
NET OUTPUT— DISSOLVED
INORGANIC SUBSTANCES 14.6X
pH OF STREAMWATER
5.1 DOWN TO 4.3
TO DOWNSTREAM ECOSYSTEM
The diagram summarizes some of the ecological effects of the deforestation of
Watershed 2 in the Hubbard Brook Experimental Forest. The rates at which the
processes are taking place are based on data obtained during 1966-68, and are
expessed in terms of increases above those observed before the watershed was
deforested. High nutrient concentrations, coupled with the increased amount of
solar radiation, have resulted in significant eutrophication. This study is an example
of how a known change in one component of an ecosystem can change the structure
and function in another section of the same or related ecosystem in an unexpected
way.
program for the IBP and the Inter-
national Hydrological Decade.
The Value of the Small-Watershed
Approach
The small-watershed approach has
already shown its power to draw
together aspects of the fields of mete-
orology, limnology, geology, soils,
hydrology, biology, and ecology into
one coherent study on the structure
and function of an ecosystem. This
type of approach is basic to advance-
ment of knowledge of how landscapes
really work. In turn, good land-use
planning is dependent on knowledge
of the structure and function of
ecological systems.
Although the hydrologic aspects
of many types of watersheds, forested
and otherwise, are under study, there
are relatively few watersheds where
comprehensive biogeochemical stud-
ies are under way. This is a serious
deficiency and should be remedied.
Comparative small-watershed studies,
where the watersheds are well de-
fined, should be initiated in all major
biomes where they are presently not
part of IBP planning. Twenty to
thirty of these studies scattered
throughout the North American con-
tinent in various biomes and involv-
294
FOREST ECOSYSTEMS
ing undisturbed and man-manipulated
ecosystems would be a modest start.
Other Needed Activity
Several other deficiencies are ev-
ident when one considers comprehen-
sive ecosystem studies. One of the
major goals of ecosystem study is to
improve our capacity to predict the
behavior of ecosystems under various
kinds of stress. Modeling, ecosystem
analysis, and simulation of ecosys-
tems are aimed at improving predic-
tive capacity. Our capacity to meet
these needs is growing haltingly,
although there is a strong need for
a centralized laboratory dealing with
the mathematical aspects of ecosys-
tem analysis. This lab could do
research on its own and cooperate in
modeling, analysis, or simulation of
various ecosystem studies under way
or planned.
One of the great problems facing
teams of scientists ana i forest
(or other ecosystems) is physical
and chemical analysis of thousands
of samples of plant and animal tissue,
air, water, soil, and the like. Service
laboratories charged with these types
of analyses and with the develop-
ment of new sampling techniques
would be of great utility in accelerat-
ing and expanding studies of the
many terrestrial and aquatic ecosys-
tems that make up the continental
United States.
Tropical Forests
Tropical forests now cover about
5 billion of the approximately 10.6
billion acres of the world that are
still forested. These forests are
among the most poorly known areas
of the world, especially with respect
to their ecology. This condition is
particularly unfortunate because there
is no other system with comparable
productivity that covers more than
a small fraction of the area occupied
by the tropical forests. Because of
our ignorance, these forests remain
one of the most poorly used of the
earth's resources.
General Description of Tropical
Forests and Soils
Evergreen "tropical rain forest,"
the most productive of the tropical
forests, is found in the lowlands
where rainfall is high and where dry
periods, if they occur, are very short.
Evidence suggests that the forest
itself appreciably increases its own
rainfall through the water that evapo-
rates from its canopy. Semi-decidu-
ous and deciduous forests are found
in areas with high humidity but dry
seasons of several weeks to months.
Dry seasons of several months permit
development of a continuous, but
relatively dry and less well-developed,
forest; if dry seasons are longer,
forests can exist only as patches,
small groups, or single trees separated
by grassland.
The adaptive characteristics of
tropical forests (and the problems
from man's point of view) are largely
the result of interactions between
the rather uniformly high tempera-
tures and the amount of rainfall.
The physical character of most tropi-
cal soils is such that both water and
air can move through at least the
surface layers relatively easily; thus,
as long as the forest canopy is intact,
rainfall does not cause much erosion.
In over half the tropical land area,
however, heavy precipitation has re-
sulted in the solution and leaching
away of almost all but the most
resistant oxides of iron and alu-
minum. Where leaching has been
extensive, availability of plant nutri-
ents and soil fertility is generally
very low.
Tropical trees are successful under
these conditions largely because they
have developed efficient mechanisms
for nutrient cycling. This is accom-
plished by the shallow root systems,
which acquire minerals as fast as
they are released from fallen leaves
and branches during their rapid de-
cay. Thus, the few minerals obtained
from the soil and the rain per unit
of time are not allowed to escape.
Because of the efficiency with which
minerals are captured following their
release through decomposition of
dead organic matter, the amount of
minerals tied up in the vegetation
frequently rivals — and for a few
elements exceeds — the amount in
the soil. (Even so, productivity of
many tropical forests is limited by
lack of some mineral nutrients; dis-
covery of effective methods of pro-
viding more of these minerals could
greatly improve forest production.)
Nutrient availability is higher in
some of the younger volcanic soils
scattered throughout the tropics be-
cause there has not yet been time
for complete leaching to take place.
Some of the relatively shallow soils
on steeper slopes are also richer than
the deeper soils on level areas be-
cause erosion keeps sending the most
leached soil down the slope, permit-
ting tree-root systems to penetrate
to newer soil formed from the parent
rock below. By temperate-zone stand-
ards, however, even these relatively
rich tropical soils are often of low
fertility.
Land Management in the Tropics
Traditional native practice in tropi-
cal forests is to cut some or all of
the trees in a small area and then
to burn them. Nitrogen supplies are
295
PART IX — TERRESTRIAL ECOSYSTEMS
lost by this slash-and-burn method,
but the ashes contain the other min-
erals that had been held by the trees
and thereby provide enough fertility
for one or more years of primitive
crop agriculture. After several years,
so much of the mineral has been
leached away that the land becomes
too poor to crop and new land
must be cleared. In some slash-and-
burn techniques, additional trees are
brought in (especially from the
slopes) and burned on the cut-over
areas along with the normal slash;
crop production can then continue
somewhat longer than usual because
of the increased amount of fertilizing
ash provided. In some areas, it is
necessary to maintain a cover on
the soil at all times if the lateritic
soil is not to be destroyed by the
combined effect of direct rain and
sunlight.
Shifting cultivation (slash-and-
burn) techniques can work well
enough to support low populations,
but they require a great deal of land.
Five to fifteen years of forest fallow
are needed to allow rebuilding of
the trees' mineral supply; this means
that, at best, several times the area
cropped must be available in order
to provide continuous support of a
farmer.
Modern Techniques — In general
terms, the methods of increasing
yields are the same in the tropics
as in temperate areas. Nevertheless,
attempts to transfer temperate-zone
ecology and agricultural practices di-
rectly to the tropics have usually
met with failure, occurrences which
emphasize how much we have yet
to learn. Techniques of replacing
slash-and-burn methods with care-
fully designed crop rotation (fre-
quently including care to maintain
continuity of a canopy) are now
being developed. They show some
promise, but a great deal more re-
search is needed. Fertilizers can be
very effective, but poor understand-
ing of soils and of plant requirements
means that the kinds and combina-
tions of materials that would be most
useful on each are unknown. Re-
quirements and effective methods of
application are generally not known
for major nutrients or for trace ele-
ments.
Water-conservation (and erosion-
inhibition) devices such as bunds,
terraces, mulches, tie ridges, and so
on are useful. Irrigation can be very
effective, but there are usually un-
considered costs associated with the
use of dams and reservoirs. Perhaps
the most important of the latter is
the effect that dam-associated flood
control will have on downstream
lowland alluvial soil such as those
along the lower Nile. Fertility of
these soils has remained high, some-
times in spite of millenia of intensive
farming without fertilizers. This is
because of the annual natural mineral
input of the deposited flood silt.
Comparative costs of maintaining fer-
tility of these alluvial soils in the
absence of flooding are unknown.
Rebuilding Degraded Soils — If
much produce (lumber, crops, etc.)
is to be removed from an area, this
will remove the nutrients incorpo-
rated in the produce. Where the
nutrient cycling is tight, as in tropical
forest, crop removal can result in
spectacular fertility-loss rates. Even
if all the unused parts of the plant
are returned to the mineral cycling,
the fertility of the soil will decrease.
Techniques need to be developed to
replace these losses from crop re-
moval and mineral leaching and to
learn how to provide additional min-
erals so that production can be in-
creased. For example, many tropical
soils have properties that are espe-
cially effective in the making of added
phosphorus and some trace min-
erals.
The extent of forest in many parts
of the tropics, especially in the dryer
areas, is being reduced by fire and
by overgrazing by domestic stock.
Grasslands are replacing forests and,
partly because grasslands have less
close minerals cycling than forests,
the quality of these soils is being
degraded. (See Figure IX-10) Activi-
ties of man and his stock have already
produced large areas of white-sand
savannah which have very low pro-
ductivity. Even if the influence of
man and stock were removed, re-
forestation would be slow because the
soils have been so greatly damaged.
Efforts must be made to learn how to
counter the soil-degradation processes
that have produced these areas and
how to rebuild the soils that have
already been degraded.
Forest Management for Production
Timber — Although tropical areas
contain almost half of the world's
forests, they produce only about one-
tenth of the world's timber. Only
about one-sixth of the tropical forest
is being exploited for timber, in
part because of the inaccessibility of
about 60 percent of the forested acres.
There are several reasons for this:
lack of road networks and vehicles;
poor markets, which means that
building roads and buying vehicles
for timber harvest is uneconomical;
low levels of available technology;
the fact that many tropical hardwoods
are so heavy that they will not float,
thus precluding use of rivers to float
logs as is common in the higher
latitudes; and the diversity of tree
species usual in tropical forests. This
diversity means either that many
kinds of timber must be cut and
marketed or that a great deal of
effort must be expended to extract
only the few species desired from
an extensive and highly varied forest.
Much research needs to be done
on these problems. If clear cutting is
practiced, or even enough trees are
taken that the integrity of the canopy
is destroyed, soil destruction can oc-
cur and erosion may be severe. In
some parts of the tropics, soil will,
in effect, turn to stone when so ex-
posed. In other areas, siltation from
erosion following timber extraction
of forest clearing has produced se-
rious problems. For example, silta-
296
FOREST ECOSYSTEMS
ORIGINAL WOODLAND-
evapotranspiration continuous
greater part of year
Soil at Field Capacity
ajsrasggggga
W ^-?: i-V ,>!> 'X^'t'" - *-,*£,? ^^■'*^^#s'*^^'' ILayerof Saturated Soil
'lllllllllillilllllllllllllllll/lllllll/llililllllllli/,
i Impermeable Layer*
I
The illustration shows the differences between a forested area and an unforested
one in Rhodesia. In the forested area, the depth of soil and amount of water are
sufficient to support the growth of trees. Evapotranspiration (a combination of
water loss by evaporation from the soil and transpiration from plants) is in balance
with the available water supply. Once the tree cover is removed, evapotranspiration
is reduced, thus allowing the water table to rise and reducing the depth of usable
soil. The net result inhibits crop growth.
tion following poor forest-utilization
practices has greatly decreased the
life expectancy of reservoirs; it some-
times causes problems by silting up
irrigation channels and often reduces
efficiency and causes damage to
pumps through clogging and abra-
sion. If the silt can be deposited on
the cropland, it provides fertilization
(but at a high cost). Research needs
to be done to find out how best
to crop the timber of these forests
with minimal damage and promotion
of minimal forest-regeneration time.
The relatively little developmental
work that has been done on intensive
management techniques to increase
the timber yield of tropical forests
suggests that it will be possible, with
more understanding, to raise produc-
tivity to at least three times present
natural levels. Under some circum-
stances, natural productivity may be
surpassed by twenty times — or pos-
sibly even more. Much research will
be required, however, if this goal is
to be reached.
Tree Monocultures — Biological
mechanisms that operate to control
populations of various plants and
animals appear to be more prevalent
and more effective in the tropics
than in temperate and arctic zones.
The high diversity of tropical forests
may, in part at least, be a response
to this condition. When attempts
are made to grow monocultures of
various tree species or other crops,
therefore, tropical populations may
be subject to particularly severe bi-
ological attack. For example, it has
so far proved impossible to establish
successful rubber plantations in
South America, the home of the Para,
or hevea, rubber tree, because of
disease problems. Under natural con-
ditions, where rubber trees are widely
scattered, disease is transmitted
poorly because of the distance be-
tween trees.
The biological attack that many
tropical monocultures suffer can be
blunted or stopped in some instances,
but the problems are frequently se-
vere and a great deal of good research
is needed for their solution. The
problem has been partly overcome
(or avoided) for some species by
transporting them to parts of the
tropics in which they are not na-
tive — with great care taken not to
transport simultaneously their dis-
eases or insect pests. The highly
productive rubber plantations in Af-
rica and Southeast Asia, for example,
were started with South American
trees.
This technique can doubtless be
useful in the future, but it is of
paramount importance that careful,
thorough, and appropriate research
precede it. Inadequate research could
lead to release of species in areas
where, in the absence of their natural
biological controls, they would spread
to become pests of major magnitude.
This could produce a catastrophe that
would dwarf the disaster that fol-
lowed the release of prickly-pear
cactus in Australia. By 1900, this
cactus covered an estimated 10 mil-
lion acres, and by 1925 it had spread
to about 60 million acres; in half of
this area, the cactus was so dense
that neither man nor horse could
enter.
Looking to the Future
Genetic breeding programs for
most tropical plants, with a few out-
standing exceptions, are not well
developed or are not being carried on
at all. With respect to forest trees
and their yield, enough has been done
with a few temperate species to dem-
onstrate that programs of this kind
can be of great benefit in increasing
yield and decreasing inter-cropping
interval. Tropical-tree yield can
doubtless be greatly increased as
well, and research and breeding pro-
297
PART IX — TERRESTRIAL ECOSYSTEMS
grams should be greatly increased.
An obvious problem is that breeding
programs with trees progress slowly
because of the amount of time re-
quired for trees to grow to the point
where they can reproduce.
Because of their high productivity
and even higher potential it might
be possible to develop tropical for-
ests as a major new food source.
For example, leaf extracts of a number
of species have a high protein con-
tent and large amounts of digestible
carbohydrate. Research is needed to
determine the best methods of leaf
collection and food extraction and
how to handle the disagreeable aro-
matic, gummy, or other substances
that are often produced by tropical
trees. Additional work will also be
needed to determine how to package,
advertise, and sell these products.
Traditional food habits of most peo-
ples are hard to change, even when
such change could result in a distinct
improvement in their nutrition.
Some tropical trees have useful
pharmacological properties. About
half of the new prescriptions cur-
rently written contain one or more
plant products as a major active in-
gredient. The tropics have been an
especially rich source of these chemi-
cals and there is no doubt but that
further investigation will be very
rewarding.
Several other problems should at
least be mentioned. One has to do
with the use and misuse of resources
provided by animals of the tropical
forests in the form of meat, hides,
pets, and experimental animals. An-
other relates to the reservoir of dis-
ease, disease vectors, and pests pres-
ent in tropical forests. A third
results from the interaction of vegeta-
tion and the hydrologic cycle and on
the effects of irrigation, each of which
can produce appreciable effects on
local (and perhaps distant) rainfall
amounts. A fourth concerns the ef-
fects of wartime defoliation on large
stretches of forests and the problems
involved in providing for their rapid
recovery (or the development of
really good alternative uses of the
affected areas).
Although it may not now be much
of an immediate problem, the rate at
which air pollution is increasing could
pose a serious problem to parts of
some tropical forests. As a result of
efforts of many of the less developed
countries (which are primarily tropi-
cal) to industrialize, local air pollu-
tion may increase rapidly. Many of
these countries may be too poor to
be willing to pay for unprofitable
pollution-abatement programs and
processes.
A possible longer-term problem is
related to the fact that tropical species
generally are more sensitive to tem-
perature fluctuations than are tem-
perate species. This means that if
man's various activities should cause
either a warming or, as now seems
more likely, a cooling of the climate,
the tropical forests could be in real
trouble. Removal of these forests
could itself contribute to this cooling
through resultant increases in albedo
and in atmospheric dust. In either
event, a useful ecological generaliza-
tion is that species from stable en-
vironments (as in the tropics) are
more sensitive to temperature and
chemical effects than are those from
fluctuating environments (as in tem-
perate zones).
Finally, because of the magnifi-
cence and complexity of the biologi-
cal system that is represented by
tropical forests, they will serve as
excellent resources in the develop-
ment of man's understanding of the
ecological enterprise and as an area
to which he can go for rebuilding
and refreshing the human spirit.
Efforts should be made to preserve
parts of these forests, and to make
them readily available for these
purposes.
Comparison of Temperate and Tropical Forests
Whether we like it or not, feel it
dangerous or laudable, the human
race must prepare itself for a gigantic
task: managing the earth's surface!
This task is not, of course, the con-
cern of any single nation or race,
but it is obvious that the highly in-
dustrialized nations of the northern
hemisphere must take the lead in
tackling the job before us, because
they have the economic wealth, sci-
entific manpower, and industrial
force to begin to undertake the task.
It is natural that we, as a people
of the temperate zone, take our own
environment, the deciduous forest or
grassland biome, as a reference point
in trying to understand other terres-
trial environmental features. This
way of thinking is sometimes dan-
gerous, especially if we try to draw
conclusions from management prac-
tices in one area and transfer this
concept to another. For present pur-
poses, however, it is valuable to start
from a few principles common to all
productive areas of the world and
elaborate the differences from these.
The State of Scientific Knowledge
The temperate zone has at least
three very distinct forest formations
in which the ecology, especially the
sensitivity to human impact, is en-
tirely different: deciduous forest;
chaparral; and laurel forest. Tropical
areas are even more complex in this
298
^TEMS
respect. One can distinguish among
lowland tropical or equatorial rain
forest, subtropical rain forest, sea-
sonal forest, forest savannah, and
tropical mountain forest. These for-
est types all have some common and
some unique features, which do not
clearly separate themselves into tropi-
cal or temperate; for example, ever-
greenness appears in both regions.
A selection of compositional, struc-
tural, and functional criteria are com-
pared in Figure IX— 11. Here, the dis-
cussion will center on comparisons
between temperate deciduous forests
and tropical rain forests.
Although we know a great deal
about the properties of almost all
existing vegetation types, we seem
hopelessly confused about how much
of each vegetation type exists in the
world. The terminology for distinct
types is weak, and the accounts of
different authors conflict. Even in
such apparently clear traditional
groupings as forest, grassland, desert,
and cultivated land there are many
discrepancies about areal extent.
Total land surface is always the same,
of course — 147 million square kil-
ometers. But statistics for various
vegetation types gathered within the
past fifteen years, including the offi-
cial calculations of the Food and Agri-
culture Organization, vary greatly.
Thus, one can find the following
estimates:
Figure IX-11 — COMPARISON OF TEMPERATE AND TROPICAL FOREST 1
Land
Type
Square
Kilometers
(millions)
Forest
38-50
Boreal Forest
12-23
Tropical Forest
15-20
Grassland
24-40
Tundra
6-7
Desert
14
Cultivated Land
14-17
a.
Properties
Predominantly
evergreen
leaf cover
(yes or no)
Height
of stand
(feet)
Approx.
leaf area
index
x ground
surface
covered
Coniferous
species
present
Functional
annual sea-
sonality (yes
or no) and
ruling force
temperate deciduous
no
> 100
~ 10
rare
yes;
forest
temperature
chaparral
yes
<100
5-12
present
yes;
temperature
+ rain
laurel forest
yes
< 100
9
rare
yes;
temperature
lowland tropical
yes
> 180
3-11
absent
no
rain forest
subtropical rain
yes
> 120
8-15
rare
yes, weak;
forest
rain
seasonal forest
yes/no
> 100
10-22
rare
yes; rain
forest savannah
no
< 100
?
absent
yes; rain +
temperature
tropical mountain
yes
<100
2-8
variable
no
forest
ra re to
present
The table lists several properties of forest types and compares these within the
temperate and tropical zones. Note the importance of temperature in the tempera-
ture zone and that of rain in the tropics.
Discrepancies are even greater with
respect to subdivisions of the above-
mentioned formation classes.
Such uncertainty offers a weak basis
for world management planning. A
new plan must incorporate the evalu-
ation of a new size inventory for
whatever the management units might
be. These units are fairly easy to
establish along the biome concept,
which coincides generally with the
"zonal vegetation," "climax vegeta-
tion," or "vegetation formation" of
the phytogeographers.
Classical Models — Any manage-
ment plan requires a model. The
"models" of the ecologically oriented
phytogeographers have traditionally
included the following categories: (a)
altitudinal profile; (b) soil pattern and
catena; (c) climatic (microclimatic)
pattern; (d) species composition; and
(e) successional series.
The correlation between some of
these properties is so significant that
predictions can be made in the tem-
perate zone and, to a lesser extent,
in the tropics. The predictions are
usually more reliable for plants than
for animals; they are usually better
for qualitative statements than for
quantitative statements; and they are
normally better for dominant species
or factors than for the less important
components. In the deciduous forest,
the traditional models are already re-
fined and commonly used for manage-
ment practices. In the humid tropics,
they are generally an order of magni-
tude cruder; some are just being elab-
orated. A generalized model of a suc-
cession, including productivity data,
is impossible to draw for the humid
tropics with any degree of confidence.
Knowledge of tropical and tem-
perate-zone ecology is about equal
almost everywhere. However, knowl-
edge in certain geographical regions
or with regard to certain factors may
be more advanced in the tropics, and
299
PART IX — TERRESTRIAL ECOSYSTEMS
the knowledge gained there shows
reverberations and applications in the
temperate zone.
Mathematical Models — Modeling
in the sense that it is used today with
regard to systems analysis — i.e.,
mathematical or computer modeling
— exists for partial processes in many
cases in the temperate forest area,
only rarely in the tropics. No entire
ecosystem is yet completely under-
stood and modeled in any biome.
This work is just now being under-
taken by several thousand ecologists
working in different parts of the
world.
The Analysis of Ecosystems Pro-
gram of the U.S. International Bio-
logical Program has as its ultimate
goal to provide the next generation of
scientists with an ecosystems model
that gives a satisfactory approxima-
tion of the following structural and
functional characteristics of the vari-
ous terrestrial ecosystems: (a) pro-
ductivity range; (b) turnover rates of
matter and nutrients; (c) species di-
versity; and (d) environmental pa-
rameter ranges with special emphasis
on energy, temperature, water and
substitute levels of nitrogen, phos-
phorous, potassium; and others. Fur-
ther, the program will help us to
secure sufficiently accurate data for
the elaboration of a general ecosys-
tems model that enables us to predict
functional and structural responses of
any given ecosystem to man-made or
accidental changes.
It will take several more years of
intensive study to develop predictive
models for population changes and
chain reactions caused by the elimi-
nation or introduction of species or
groups of species. These "sensitivity
investigations" may provide the most
important results from present eco-
systems studies. In many cases,
changes are surprising and significant
but apparent only after several years.
It might be easier and quicker, there-
fore, to study the effects of some
interferences in tropical environments
her than in temperate zones, be-
cause development periods are shorter
and uninterrupted by a rest period.
Genetic studies have applied this
principle successfully in many cases,
and ecologists should do the same.
The results of such studies in tropical
areas will provide us with models that
will help us to manage our own envi-
ronment, especially in the southern
United States.
For some of the large-scale changes
that man imposes upon the environ-
ment, predictions are already possi-
ble. Thus it is probably safe to predict
that, in South America, large-scale
traditional (temperate-zone) agricul-
ture in the Amazon-Orinoco water-
shed will fail, that the Rio Negro
region will change from a black-water
stream to a white-water system, that
all sorts of unpredictable changes in
the fauna will occur as a result of the
removal of several natural environ-
mental barriers, and that fantastic
changes will follow in every respect.
It is probably unsafe, however, to
predict what would happen to the
atmosphere if all the tropical regions
of the world were cultivated. The
data base is too slim for any reason-
able prediction. We can only define
certain areas that are likely to become
problems: for example, the change of
tropical air masses from an almost
constant carbon dioxide level to an
as yet unpredictable fluctuation; or
the potential threat of airborne dis-
ease originating in the tropics (espe-
cially fungal diseases of plants) for
plants, animals, and man. The at-
tempt to establish large human settle-
ments in the humid tropics of South
America raises problems of unknown
magnitude. For example, sanitary
sewage disposal in an area saturated
with water and at such a temperature
level is a gigantic problem, and the
prospect of industrial sewage is even
more dire.
Needed Scientific Activity
The primary reason that ecology
was previously the "Cinderella" of
the biological sciences is the fact that
an incredible number of species are
ruled by an unwieldy number of
forces, and the species in turn influ-
ence the forces. The analysis of an
ecosystem always seemed an unman-
ageable task, even assuming that only
the most important components were
to be studied. The recent develop-
ment of systems analysis, the teach-
ing of team studies, and the ever
growing computer capacities give us
a more realistic chance for a valid
ecosystem model. But all these tools
are useless without a willingness of
many scientists from several disci-
plines to cooperate in one study and
generate the necessary data pool for
individual cases.
Data Base — The data base for the
prediction of human impact is com-
pletely incomparable in deciduous
and tropical forest areas. From the
standpoints of an ecosystems mod-
eler, the data base is totally lacking
to unsafe or, occasionally, satisfactory
in tropical areas and sometimes suffi-
cient to unsafe in the deciduous forest
areas. A general judgment is not
possible because the knowledge nec-
essary for the understanding of eco-
systems is so different in the various
disciplines. It is still necessary to
conduct major investigations and col-
lect a sound set of data if one cares
about accurate models that are mean-
ingful for management purposes.
Instrumentation — The sensors and
techniques to acquire the necessary
data are generally adequate, though
their reliability and durability are
usually better in temperate zones
than in the tropics. It is, of course,
always necessary to develop new
tools for the constantly changing
tasks before us. For the elaboration
of better and more complete ecosys-
tem models, we foresee the need for
simulators and analogue computers of
larger dimensions. Many computing
facilities today still have only the
capacity to confirm the conclusions
that people had drawn from hand
calculations. How quickly progress
will be made naturally depends on
300
FORES I
the demands of scientists and the
adequacy of public support.
Ecosystem Models — The develop-
ment of ecosystem models is pre-
requisite to an adequate understand-
ing of environmental problems. A
single model is infeasible at the mo-
ment, but we see this as a future goal.
The development of a set of models
is the immediate necessity as a base-
line for application in both manage-
ment and teaching.
The set of models to be developed
needs to include all of the classical
models mentioned earlier, but better
quantification is needed for many pa-
rameters. Tropical areas need much
more work for the elaboration of such
models than temperate zones. Spe-
cifically, the following sets of models
— in the form of abstract mathe-
matical equations, matrices, or proba-
bilistic or stochastic statements — are
needed for understanding and pre-
dicting human impact on the bio-
sphere or environment:
1. Global Level
(a) Production capacity of vege-
tation; responses to average
levels of growth factors like
radiation, temperature, wa-
ter, nutrients, pollutants;
utilization of vegetation by
animals and man;
(b) Optimal carrying capacity
of the earth for men under
various possible manage-
ment practices;
(c) Interaction of vegetation
and the physical environ-
ment; circulation of carbon,
oxygen, and other sub-
stances through atmosphere,
biosphere, hydrosphere, and
geosphere; quantity and rate
(circulation speed) need to
be investigated.
2. Biome Level
(a) Production rate of vegeta-
tion;
(b) Utilization practices of ani-
mals and other consumers;
(c) Decomposition rate;
(d) Reasons for homeostasis and
the equilibrium level of
forces that maintain it;
(e) Efficiency of energy utiliza-
tion;
(f) Man's management prac-
tices and their influence on
the system's turnover rates.
3. Regional (Landscape) Level
(a) Production, consumption,
and decomposition in bio-
cenoses; reactions to levels
and specific fluctuation pat-
terns of external and inter-
nal forces like radiation,
temperature, water, nutri-
ents, pollutants, animal
feeding, etc.;
(b) Developmental patterns of
species in space and time;
(c) Qualitative responses of the
regionally available species
pool with regard to different
environmental matrices;
(d) Chemical diversity within
the food web.
Such a model can only be developed
if comparisons are available from all
contrasting biomes, although some
biomes are more important than
others for the development of a gen-
eral model. For example, inclusion of
a humid tropical forest is essential,
since these forests represent either
the absolute maximum, optimum, or
minimum realized on earth for many
of the ruling environmental forces.
Turnover of matter and energy in the
humid tropics is twice as fast as in
the temperate area. Tropical areas
contain at least 60 percent of the
world's natural resources. Again, the
humid tropics are especially suscepti-
ble to human impact, since their soils
and climate and orographic conditions
are highly sensitive. This is especially
true for modern agricultural tech-
niques, utilization of high-yielding
varieties, and constant shielding with
pesticides and insecticides.
301
PART IX — TERRESTRIAL ECOSYSTEMS
3. FOREST ANIMALS
Problems of Animal Ecology in Forested Areas
Traditionally, the study of animal
ecology in forested areas of the
United States has been concerned
only with species that are either in-
jurious to man or to forests or are
game animals of interest to the
hunter. To these original concerns —
i.e., the impact of animals on the
forest and the availability of animals
for man — we should now add two
more: (a) the impact of man on forest
animals, and (b) the needs of forest
animals for suitable habitat.
Large and small forest animals and
birds affect man's aesthetics, eco-
nomics, and, occasionally, his health.
Furthermore, the greatly increasing
pressure of man on the wildlife re-
source of the forests has created seri-
ous problems. Sometimes control of
animal populations is necessary or
desirable; this is true in the urban-
suburban fringe as well as in na-
tional parks and private recreation
areas. At other times, the need is to
promote the integration of forest
wildlife into the urban and semi-
urban scene, where the presence of
wildlife provides an antidote to some
of the stresses of urban living.
The State of Animal Ecology
Research
Forest animals vary greatly in their
adaptations, both to the type of forest
and to the relative amounts of forest
and open land that they require.
Many forest animals are more accu-
rately forest-edge animals; the white-
tail deer is a prime example, and any
consideration of white-tail habitat
must involve the relative proportions
of forest and opening. In addition,
year-to-year differences in environ-
mental conditions may have drastic
influences on the animals. The im-
pact of winter weather on the survival
of the ruffed grouse is a case in point.
Low temperatures, snow depth, and
the conditions of the surface of the
snow all play a part in the survival
of the bird: that is, ruffed grouse can
survive long periods of extreme cold
provided that adequate snow is avail-
able and uncrusted, so that the bird
can penetrate into the snow for night
roosting. With deer, light snow per-
mits ready movement but deep snow
restricts it. Similarly, environmental
differences between locations influ-
ence the behavior, feeding ability, and
survival of an animal population.
Data Base — A reasonably ade-
quate base of data on forest animals
already exists. This is particularly
true for those animals important to
the hunter and sportsman, such as the
white-tail deer, ruffed grouse, wild
turkey, and gray squirrel. Data are
gradually accumulating on the life
histories and behavior of various car-
nivores, including the black bear,
bobcat, coyote (in forest habitats,
especially), and timber wolf, as well
as on many smaller mammals, both
predators and herbivores.
Knowledge of gross food supplies
for forest herbivores is readily avail-
able, but more important are the data
now being gathered pertinent to the
calorie content of this food and to the
fluctuation in mineral constituents —
i.e., on the quality of the animals'
food. Much data have been accumu-
lated on browse for white-tail deer,
lesser amounts of information on
fruits and nuts.
But there are sizable gaps in our
understanding of the utilization of
food and shelter. Little is yet known
of the reasons why certain plant spe-
cies are consumed in preference to
others, nor are the changes in rumen
flora of the white-tail deer under-
stood. Virtually no information is
available on forms of food materials
like forest herbs and aquatics. We
are just beginning to discover some
of the nuances of the summer food
habits of deer, the diversity of foods
used (particularly herbaceous mate-
rials), and the impact that summer
food selection may have on deer
habitat. Additionally, although we
know that crossbills and finches use
seeds of forest trees in quantity, we
know little of the relationship of
these bird populations to tree seed
crops. Food selection, utilization, and
availability are thus areas open to
considerable work relative to most
forest animals and birds.
Instrumentation — The advent of
radio telemetry has done much to in-
crease knowledge of the home range
and behavior patterns of a number of
animals and birds. For example,
movement patterns of owls have been
studied in Minnesota and the hunting
pattern of barred owls delimited.
(The owl hunts in one area until prey
populations have dropped — i.e., un-
til hunting is unprofitable; it then
moves on to another location and
another and in time returns to the
original spot when mice populations
have again reached a suitable level.)
Telemetry is also producing informa-
tion on deer behavior as well as
movement patterns for such animals
as the grizzly bear and the timber
wolf.
The impact of radio telemetry on
knowledge of animal behavior is al-
ready great, but there is ample room
for additional studies of movement
patterns and even more opportunity
for telemetry of physiological param-
eters. Improvements are presently
being made in the technology, and
much information of value will likely
be gained thereby.
302
FOREST ANIMALS
In the field of habitat research,
progress has also been made in im-
proving sampling methods. Low-
level, large-scale photography offers
excellent opportunities for improving
the analysis of wildlife habitat.
Modeling — Mathematical model-
ing has already shown some value
and will undoubtedly be useful in
clarifying many animal-habitat rela-
tionships. Theoretical formulation of
data in forest animal ecology has been
relatively slow in developing, how-
ever. The lack of suitable quantita-
tive input has been one deterrent;
another has been the slow develop-
ment of modeling techniques.
Needed Scientific Activity
Habitat Research — The single
most essential need in forest wildlife
ecology is to relate or link the animal
to its habitat in detail. Although con-
siderable data are available, the link-
ages are still far from clear. For
example, what is the relationship
between food availability and con-
sumption, or between tree cover and
energetics. Specifics are needed on
the interaction of animals with abiotic
environmental factors as well.
Answers to such questions will re-
quire both additional field studies and
the use of mathematical models that
can in turn be tested for accuracy by
field investigation. They will also re-
quire greater interest on the part of
researchers themselves. In the Lake
States, for example, despite the great
importance of forest wildlife to the
recreation industry as well as to the
health of the forest ecosystem, very
few individuals are engaged in forest-
habitat research.
With suitable additional input, con-
siderable advances could probably be
made within fifteen years in the link-
ing of animal to habitat components
- both food and shelter. Steady
progress toward this end is highly de-
sirable. Population stress and its un-
derlying causes is another area of
work that deserves attention. The
study of animals as disease vectors,
although not a major problem area,
should be continued.
Public Understanding — Despite re-
maining gaps in scientific understand-
ing, present knowledge of the ecology
of the larger forest animals probably
exceeds the ability of the land man-
ager to use this information. Today's
land manager is restricted by lack of
popular acceptance of the basic prin-
ciples of population dynamics and
habitat. Like religion and politics,
questions having to do with length of
hunting season, bag limits, and status
of animal and bird populations are
not easily settled; nor are they always
discussed rationally.
For example, it is difficult to con-
vince the public that changes in habi-
tat and weather are usually much
more effective in population control
than is the two-legged predator.
Thus, controversy always surrounds
the question of whether or not female
white-tail deer should be hunted.
And yet the known reproductive
cycle of the white-tail, its responses
to weather conditions, the effect of
severe winters on reproduction, and
the normally high replacement rate
all indicate that it is virtual!
sible to exterminate deer save on a
very local basis. Other fallacies in-
clude (a) the idea that it is possible
to "stockpile" populations of ruffed
grouse by closing the season one year
and thus have more birds the next,
and (b) the concept of predator con-
trol by bounty.
Perhaps for these reasons, the
Great Lakes Deer Group several years
ago listed public understanding as
among the most important of its
problems; the group recommended
motivational research to find out
what creates public attitudes toward
agency programs, a study that should
include the sociology and psychology
of deer-hunting and other factors re-
garding the deer herd. In general,
the most controversy results from a
lack of understanding by a major
segment of the public of the ecologi-
cal requirements for animal devel-
opment and of animal population
dynamics.
One may say with reason that there
are no strictly scientific controversies
in forest animal ecology, although
there is some disagreement as to the
relative impact of habitat and preda-
tors on populations of certain game
animals (specifically, the moose at
Isle Royale) and on deer in the Middle
West and elsewhere. The scientific
base of understanding is far from
complete, however, and as gaps in
knowledge of the animal, of animal
use of the forest, and of forest growth
are filled and the information con-
veyed to the public, scientific manage-
ment of forest animals may become
feasible.
Wilderness as a Dynamic Ecosystem, with Reference to
Isle Royale National Park
The major problem of the status of
man on earth can be approached in
some degree through studies of other
living things to assess the influences
of density factors, behavioral homol-
ogies, population dynamics, and other
phenomena common to many species.
Research in these plant-animal com-
munities must produce a better under-
standing of natural dynamics and life
renewal in native types of forest,
range, wetland, and aquatic habitats.
303
PART IX — TERRESTRIAL ECOSYSTEMS
To these basic parameters must be
added the complicating effects of hu-
man culture on both man and hi?
environment.
Gross considerations suggest that
the unguided technological culture in
the hands of a rapidly increasing
population is producing an unman-
ageable complexity in human society
and rapid deterioration in the envi-
ronment and its component resources.
If man is to endure on earth, the
entire biosphere must be his ecosys-
tem, preserved and kept productive
through conservative use and under-
standing management.
Since man has never created an en-
during, self-perpetuating ecosystem,
he has much to learn from the study
of natural processes. All conditions
relative to human use and manage-
ment are of interest and should be
studied. However, the features of
ecosystems that guarantee perpetua-
tion are most clearly effective under
primitive conditions. Thus, areas
where primitive conditions are still
operative are of special scientific in-
terest. The least-modified communi-
ties of living things are likely to be
found on lands and waters set aside
as "wilderness" or natural reserves
of one kind or another.
Isle Royale as a Prototype
Ecosystem
A roadless island of 210 square
miles in northern Lake Superior ex-
emplifies the kind of situation where
fact-finding is possible under rela-
tively undisturbed conditions. Isle
Royale is a national park and may be
visited by some 10,000 people during
the tourist season from mid-June to
early September. From the end of
October to mid-May it is uninhabited
except for a research group, using a
small aircraft, that is present for
seven weeks in February and March.
Animal Populations and Associated
Vegetation — Lying 15 miles from
the nearest Canadian shore, the is-
land is sufficiently isolated that it has
not yet been colonized by certain
mammals and birds found commonly
on the mainland — especially deer,
bear, raccoon, porcupine, and ruffed
grouse. Lynx and marten disappeared
from the island early in this century,
as did coyotes in the mid-1950's. In
the latter case, the advent of wolves
about 1949 probably resulted in elimi-
nation of the smaller competing canid.
The fox does not appear to have been
affected by such competition.
The boreal forest and hardwood
vegetation of Isle Royale was exten-
sively burned over in the past cen-
tury. Alteration of "natural" condi-
tions by this human disturbance must
be considered a matter of degree,
since burning also took place in
primitive times. The dynamics of
forest successions is, in any event,
significant. Early successional stages
produce food and cover for such crea-
tures as snowshoe hare and beaver,
as well as browse for the moose.
Thus, burning incident to drought
cycles renews the habitat of many
herbivores and indirectly supports
their dependent carnivores.
The mammal populations of Isle
Royale have shown the instability
that characterizes simplified animal
communities. The moose illustrates
this, since it reached the island in the
first decade of the century, before its
primary enemy, the wolf, was pres-
ent. As a result, by the mid-1920's,
moose had overpopulated and de-
stroyed most of the available browse.
In ensuing years, as a result of mal-
nutrition and disease, moose died
down to a low level. A fire in 1936
destroyed forest cover and initiated
new brush-stage successions on about
a third of the island. Moose were
building up again when wolves
crossed the ice and became estab-
lished in the late 1940's.
The Meaning of a Dynamic Wil-
derness — In areas like Isle Royale,
the U.S. National Park Service and
other land-management agencies have
been enabled to get a new view and
concept of "wilderness" as a dynamic
condition. Thus, a full spectrum of
successional stages and habitat condi-
tions enables a vegetation zone to
support a wide variety of animal life.
On any given site, animal life must
change with maturation of the forest
or other vegetation. In terms of land
management, this means that agen-
cies charged with the administration
of natural areas must regard fire as
a part of the primitive scene that
should not be totally eliminated, even
if this were possible. A strictly ap-
plied policy of fire suppression would
lead to the development of extensive
monotypes representing the "climax,"
or stability phase, of plant life in a
region. This would correspondingly
reduce variety in both flora and
fauna.
Predator-Prey Relationships —
Biological studies carried out by Pur-
due University on Isle Royale over
the past twelve years have been sig-
nificant in revealing predator-prey
relationships. The moose is the larg-
est member of the deer family and
the gray, or timber, wolf is its only
effective natural enemy. In natural
communities, large browsing and
grazing animals depend in major de-
gree on their predators for population
control, the alternative being range
damage and violent fluctuations in
number. When it became known in
the early 1950's that wolves had
reached Isle Royale, it was evident
that this was a situation in which nat-
ural relationships of the two species
could be studied.
The major findings of the ensuing
research program elucidate a mutu-
ally beneficial relationship between
predator and prey, an adjustment of
relative stability that, by controlling
the moose population, protects the
habitat from over-use. As of mid-
winter, an average population of 22
to 24 wolves is being supported by a
moose population of about 900. The
beaver is a secondary prey species
furnishing 10 to 15 percent of the
wolf's food. Numbers of the moose
and beaver are limited by the wolf. As
304
1 ANIMALS
in other large carnivores, wolf num-
bers are self-limited largely through
behavioral intolerances. Ordinarily
there is one pack, most commonly
around 15 animals, in which breeding
takes place, and only one female will
bear young. There has obviously
been a high mortality among young
wolves.
The remains of more than 400 dead
moose — nearly all wolf kills — have
been examined on Isle Royale and
their ages determined by tooth char-
acteristics. On this basis, a composite
life table and survivorship curve for
the moose herd has been constructed.
(See Figure IX-12) This illustrates
a relatively high mortality of calves
in the first year of life. In the next
five years of its life, a moose evi-
dently is at the peak of health and
vigor, for it is seldom taken by
wolves. From age 6 to the maximum
age of 17 + , the moose is increasingly
liable to be killed; the average adult
taken is 9 to 10 years old. Correlated
with advancing age and a higher
mortality rate is an increasing in-
cidence of physical disorders.
The high selectivity for old and
debilitated moose has been evident in
the hunting habits of wolves. An
Figure IX-12 — LIFE EXPECTANCY AND SURVIVORSHIP
OF ISLE ROYALE MOOSE
EXPECTATION OF LIFE IN YEARS
10
PERCENT MORTALITY
100
12 3 4 5 6 7
B 9 10 11 12
AGE IN YEARS
13 14 15 16
average of 12 moose have been ap-
proached and brought to bay for
every one killed. Vulnerable moose
appear to be detected readily, while
animals capable of strong defense
are quickly passed by. In effect, the
wolf culls the moose population and
preserves a stock that can utilize the
plant food supply most efficiently in
producing new generations to sup-
port wolves.
Implications of the Isle Royale
Findings
This information reveals working
mechanisms that confer durability on
the ecosystem. It may be pointed out
that population stabilization and turn-
over rate in the wolf could only be
studied where this species is protected
from unnatural mortality. The natu-
ral age structure of the moose herd
and the selection effect of the preda-
tor could be ascertained only where
moose are protected from hunting
and exposed to natural predation.
Isle Royale National Park is perhaps
the only area in the world where these
conditions are met at present.
The relationship of predator to
prey has other, more direct, implica-
tions, since big game herds are most
commonly managed in the absence
of effective natural enemies. The
chief dependence in population limi-
tation is on the gun and such factors
as highway kill. Such artificial selec-
tion will in time alter the direction
of speciation and change the nature
of such wild species as the deer. In
the preservation of wild fauna and
flora, for whatever benefits are to be
realized, there are evident advantages
in understanding the character and
dynamics of the original associations
in which living things developed.
305
PART IX — TERRESTRIAL ECOSYSTEMS
4. FOREST FIRE
Research into Fire Ecology
Fire is a useful tool in maintaining
or modifying many vegetation types.
Like all tools, however, it should be
used in certain situations and not in
others. For example, it should be
used only where it can be controlled
or where, if it escapes, the potential
damage will be minimal or at least
considerably less than the benefits.
Some vegetation types can be im-
proved by burning, others cannot.
Still others, such as certain desert
areas, support too little vegetation to
carry a fire.
Fire and climate are interrelated to
the extent that a specific kind of cli-
mate largely determines the kind of
vegetation an area can produce. This,
in turn, determines the fire-vegetation
interrelationships — i.e., the readiness
with which an area will burn, the
effects of fire on modifying the plant
cover, and the effects of this modifi-
cation on the subsequent potential
fire history of the area.
Fire can have various interrelated
beneficial effects on forests and grass-
land as well as on many woodland
(low-stature trees) and brushy areas.
It may control undesirable woody
species, thus promoting the growth
of grasses and other herbaceous
plants and, as a consequence, in-
creasing the grazing potential. This
modification often reduces soil ero-
sion and runoff, since grasses provide
a better close ground cover than
many woody species. (See Figure
IX-13) Other beneficial effects in-
clude ease and economy of controlling
accidental wildfires; soil fertilization
from the ashes; control of ticks,
poisonous snakes, and other undesir-
able animals; control of fungi in the
longleaf pine; creation of a better
habitat for game animals, including
turkeys, quail, and deer; reduction
of excessive pine reproduction; main-
tenance of profitable timber stands.
Evaluation of Current Scientific
Knowledge
There is a rather large body of
information on forest fire, much of it
from foreign countries. In the United
States, research is being carried on
by the Forest Service at the Univer-
sity of Washington, Seattle, and by
the U.S. Forest Fire Laboratory in Mis-
soula, Montana, among other places.
Significant recent additions to scien-
tific knowledge include the following:
1. Considerable theoretical work
by Anderson and Beaufiat at
the Forest Service's Intermoun-
tain Research Station at Mis-
soula.
2. Research on the practical as-
pects of fire behavior by Coun-
tryman, working out of the
Forest Service Laboratory in
Riverside, Calif.
3. Research on quantitative char-
acteristics of fire in the desert
grasslands by Claveran and
Moreno at the University of
Arizona, Tucson.
4. Research on fire temperature,
development of mathematical
formulations, and effect on
mesquite and grasses being
carried on out of Texas Tech
University, Lubbock.
5. An analysis of fire ecology by
Daubenmire.
6. An analysis by Batchelder of
quantitative external factors
such as air temperature, hu-
midity, and wind in relation to
fire behavior.
7. An analysis of fire in relation
to the various vegetation types
in the United States by Hum-
phrey.
8. An aggressive and expanding
program of research and dis-
semination of information on
Figure IX-13 — EFFECT OF FIRE ON MESQUITE SHRUBS
The illustration to the left shows how mesquite chokes out grass under normal
conditions. After a fire, the grass recovers rapidly while the mesquite recovers
much more slowly. Controlled burning will eliminate the mesquite entirely and
maintain the grassland.
306
FOREST FIRE
fire ecology that has been car-
ried on for several years under
Komarek by the Tall Timber
Research Station, Tallahassee,
Florida.
Despite the extent of the present
data base, however, the entire sub-
ject of fire ecology has been inade-
quately studied. Three aspects that
are particularly deficient are the re-
actions of individual species to fire,
the effect of repeat burns on species
and vegetation types, and mathemati-
cal modes of fire-ecosystem com-
ponent relationships. Although a few
data are beginning to accumulate that
are serviceable as a base for both
theoretical formulation and mathe-
matical modeling, relatively little of
the earlier research was suited to
this approach. Currently, there ap-
pears to be a trend in the direction of
quantitative research and a continued
increase is anticipated. Much more
is needed.
Status of Instrumentation — With
a shift from qualitative to quantita-
tive research, one progresses from
minimal use of instruments to a
need for instrumentation that is often
expensive and highly sophisticated.
Fire research today is moving in this
direction, and, as a consequence, pro-
posed investigations are requiring a
budget for equipment that would
have been unthought of only a few
years ago. Remote-sensing and moni-
toring equipment to obtain a variety
of temperature and moisture meas-
urements with time are particularly
useful in these studies. Although
much of the basic equipment is cur-
rently available, refined techniques
or specific situations will necessarily
result in some modification or re-
finement.
Interaction with Other Environ-
mental Systems — Despite the fact
that most fire research has been of
an applied nature — relating fire to
noxious-plant control, forage produc-
tion, timber yield, soil and water
losses, and water yield — surprisingly
little is known about the specifics of
fire as it relates to other environ-
mental systems. For example, many
of our forests and grasslands can be
improved for recreation and hunting
by the judicious use of fire. These
same areas can be rendered less li-
able to destruction by wildfires when
administered under a sensible pro-
gram of controlled burning. Yet this
relationship is almost completely un-
explored.
As the use of our wild lands in-
creases consequential to the greater
availability of leisure time and the
need to escape from urban conges-
tion, these lands are exposed to an
ever increasing hazard of destruction
from man-caused fires. The possibil-
ity of reducing this hazard through
a management-by-fire approach needs
to be thoroughly investigated. In
cities, we stress cleaning up poten-
tial fuel in our fire-prevention cam-
paigns; in forests, by contrast, we
encourage accumulation of fuel to a
point where an accidental fire can
become a holocaust.
Because of anti-fire propaganda
and the inadequacy of research, there
is considerable difference of opinion
even in scientific circles on the bene-
ficial and harmful effects of fire in
most vegetation types. This contro-
versy extends from the interpretation
of historical records, through the
long-time effects of previous fires and
present fire-control policies on the
"climax" vegetation, to the yield of
such renewable natural resources as
forage, game animals, timber, and
water. Obviously, these differences
of opinion must be resolvec
lands are to be used most effective!
and, in many instances, if we are
to prevent their further deterioration
or destruction.
Requirements for Scientific
Activity
The principal needed scientific ad-
vances are: (a) amplification of both
qualitative and quantitative studies
directed to specific vegetation types
and individual species; (b) greater
emphasis on man and his effect on
the wildland environment as this af-
fects the incidence of fires; (c) re-
search on controlled burning as a
means of pretreatment to control
wildfires; (d) additional research on
the generalities and specifics of fire
(controlled and wild) as interrelated
with all other aspects of specific
ecosystems; and (e) extensive devel-
opment of theoretical formulation, in-
cluding mathematical modeling. The
current scientific poverty of knowl-
edge on this topic and the rapidly
increasing rate of use of our wild-
lands by man indicate a high degree
of urgency for such research.
Necessary significant advances
could be made in a minimum of
three years. Five years would be
adequate to effect a more far-reaching
breakthrough. In addition, many
ecological studies require a long pe-
riod of time to evaluate cause-effect
relationships properly, and fire stud-
ies are no exception. Aside from
recovery time following a single fire,
fire research often requires repeat
burning at periodic intervals over a
period of years. Studies of this sort
should have a minimum duration of
25 years or more.
307
PART I\ — TERRESTRIAL ECOS\ STEMS
The Role of Fire in Forest Management and Ecology
Wildfires destroy vegetation and
wildlife, may result in erosion and
soil damage, leave unsightly vistas,
are costly to suppress, and upset
management plans and schedules.
Thus, one of the most important
tasks of the forest manager is to
control wildfire, preferably by pre-
vention. Only if the forest is free of
wildfires, can management measures
be applied as needed to yield the
maximum amount of goods and serv-
ices the forest is capable of pro-
ducing.
Prescribed fire, however, can be a
useful tool for achieving these ends.
It is often one of the measures that
may be appropriate' in manipulating
forest vegetation. But to use fire
properly it must be fully controlled.
Because of the great variation in
climate, topography, soils, and vege-
tation in the United States, a compre-
hensive discussion of the role of fire
in forest management and ecology
would require much more space than
is available here. This discussion
will therefore be limited to the lob-
lolly-shortleaf pine-hardwood forest
type, which extends from Maryland
to Texas through the middle South.
It is the most important forest type
in the southern timber economy and
one in which the fire history encom-
passes both substantially wild and
prescribed fire.
Ecology of Fire
Fire was apparently the major fac-
tor in maintaining extensive stands
of pine long before the South was
settled by man; it can probably be
considered a natural ecological factor
in southern pines. With the advent
of human settlement and, later, ex-
tensive logging, it became a frequent,
almost annual occurrence over much
of the region. Not until the organiza-
tion of public forestry agencies and
the establishment of permanent forest
industries was the custom of indis-
criminate annual woods burning
brought under control. However,
wildfire continues to be a frequent
occurrence.
Loblolly pine is the most prominent
tree species in this type of forest.
It usually occurs in relatively pure
stands, being a serai species. On
drier sites, shortleaf pine is often
mixed with it, particularly in the
western part of its range in Arkansas,
Louisiana, and Texas. Pine is fol-
lowed by deciduous hardwoods in
the plant succession, and the pine
stands characteristically have an un-
derstory of hardwood tree and shrub
species which eventually displace the
pine unless a disturbance occurs that
again favors pine.
The effect of fire in loblolly pine
stands is closely related to the bi-
ological requirements and character-
istics of the species and to the trend
toward hardwoods in the plant suc-
cession. The effect of fire on the
succession depends on the age of the
pine stand and on the intensity, fre-
quency, and season of fire occurrence.
Effect of Fire Intensity — Crown
fires at any season of the year com-
pletely destroy the pine stand. Fires
of this type occur during periods of
exceptionally high fire hazard, so
that understory vegetation is also
killed back to the ground. A burned
soil surface is an excellent seedbed
for loblolly pine, and the proportion
of pine in the new stand depends
on the supply of pine seed in the first
year or two after the crown fire. Pine
becomes established readily in the
burned area, and the resulting stand
is made up of pine seedlings and
hardwood seedlings and sprouts. In
one study, pine reproduction equalled
hardwoods in basal area but not in
number of stems nine years after a
crown fire, showing that the pine
stems were growing much faster than
the hardwoods and would probably
form the bulk of the dominant stand.
Loblolly pine stands become fairly
resistant to surface fires at about 10
years of age. Fire usually destroys
younger stands completely but sur-
face fires damage older stands very
little. Furthermore during the dor-
mant season such fires in older pine
stands have very little effect on suc-
cession. Litter is consumed and small
stems are killed. The hardwood stems
are quickly replaced by sprouting and
the thin litter permits establishment
of pine seedlings, so that conditions
quickly become as they were before,
except that hardwood stems are prob-
ably more numerous.
Effect of Season — In the loblolly
pine range, wildfires are most likely
to occur in spring, before growth
begins, and in autumn, after leaf-
fall. Winter fires are less frequent,
while summer fires occur only during
prolonged and severe dry periods.
Fires during dry periods in the
growing season may be very destruc-
tive because initial vegetation tem-
peratures are higher, growing tissues
are more exposed to heat, and sprout-
ing is less vigorous than that follow-
ing dormant-season fires. Depending
on how much of the overstory is
killed, conditions after summer fire
range from something resembling
those after a crown fire to a reduction
in the smaller understory hardwoods
only. The succession varies accord-
ingly.
Fires within the first year after har-
vest cutting differ in their effects, de-
pending on the time of the year they
occur in relation to pine seedfall.
During the dormant season they de-
stroy not only advance reproduction
but also whatever seed is present.
Hardwoods are highly favored be-
cause a whole growing season must
30S
FOREST FIRE
pass before another crop of pine seed
is produced. Meanwhile, hardwood
sprouts and herbaceous vegetation
produce a new mantle of litter that
retards pine-seed germination.
On the other hand, fires before
seedfall may favor pine establishment
if they do not occur too early in the
growing season. Hardwood stems
killed after early August sprout very
little until the following spring. Con-
sequently, fires in late summer before
seedfall not only increase favorable
seedbed conditions by consuming
slash and undisturbed litter, but also
give pine seedlings an even start
with hardwood sprouts and seedlings
the following spring. The earlier that
fires occur in the summer, the more
nearly the sprout and seedbed con-
ditions approach those following
dormant-season fires after harvest
cutting.
Effect of Frequency — While occa-
sional fires favor loblolly pine re-
generation, fires at intervals of less
than 10 years eventually eliminate
loblolly pine. Frequent fires repeat-
edly destroy the pine reproduction,
while hardwood stems are multiplied
by seedling establishment, sprouting,
and suckering. The process becomes
relatively rapid when the dominant
pine stand is clear-cut or otherwise
destroyed. Continued frequent burn-
ing may ultimately result in a vegeta-
tional type dominated by grasses.
Effects of Fire on Soil
Fire heats the soil only very shal-
lowly, but it affects the surface soil
both physically and chemically.
Physical effects range from none or
negligible to measurable.
The texture of the surface soil may
be a factor. Thus, in the coastal
plain of South Carolina, a fire-effects
study showed no reduction in bulk
density, total porosity, or percolation
rate down to a depth of four inches,
even after ten annual fires. Yet, in
other coastal-plain locations, investi-
gators have remarked on the com-
pactness and reduced permeability
of the soil surface after burning.
It is logical to expect a greater
effect on soils of heavier texture. A
difference in effect on plant growth
attributable to soil texture and drain-
age characteristics was found in a
study in northeastern North Carolina,
where the area occupied by hardwood
sprouts increased rapidly for three
years after logging and site prepara-
tion and then grew more slowly. On
soils with poor surface drainage and
plastic subsoils, hardwood reached
85 percent ground coverage in five
years without burning but occupied
only 65 percent in burned areas. On
soils with good surface drainage,
burning had the opposite effect: hard-
wood cover increased faster on
burned than on unburned areas,
reaching about 10 percent greater
coverage after five years.
Erosion following fire is not a con-
cern in the flat coastal plain but may
be a danger farther inland on more
pronounced topography. However,
instances of serious erosion following
fire in the loblolly pine range have
not been reported. It may be that
the vegetation grows back fast
enough to protect the soil surface
when the high-intensity summer
storms occur.
Fertility — Burning usually results
in an increase in organic matter in-
corporated in the surface soil. Fire-
charred material filters into the upper
layer. In addition, the ; mount
of herbaceous vegetation that usually
follows burning, especially grasses
with their abundant fine roots, may
be a source of increased organic mat-
ter. These observations are from
coastal plain locations. On sloping
land, water would tend to carry ash
and charred material from the site
and organic matter increases might
not be so pronounced; organic matter
might even be reduced on heavier
textured soils.
Soil chemical properties are usually
improved for plant growth after fire.
Calcium is increased appreciably,
with an accompanying decrease in
acidity. Other mineral elements may
be increased slightly through release
from the litter. (See Figure IX-14)
Nitrogen is increased, apparently
from several sources. Burning re-
leases much of the nitrogen in the
litter but some remains in fire-charred
material, which is concentrated close
to the soil surface. The increase in
herbaceous plants includes not only
grasses but also legumes, possibly
providing a source of nitrogen. How-
ever, an observed annual increase of
23 kilograms per hectare in annually
burned loblolly pine stands in the
lower coastal plains of South Carolina
could not be accounted for by the
transfer of nitrogen from the litter to
the mineral soil.
Soil organisms in the litter and
humus layers are destroyed by burn-
ing, but the effects have not yet been
comprehensively investigated. Ap-
Figure IX-14 — QUANTITIES OF NUTRIENTS RELEASED
BY BURNING TROPICAL VEGETATION
Tropical rain forest
(forty years old)
Savanna woodland
PHOSPHATE POTASSIUM CALCIUM MAGNESIUM
112 731 2,254 309
7
41
31
23
The table gives an estimate, in terms of pounds per acre, of several nutrients that
are released to the soil by burning vegetation in two different tropical regions.
309
PART IX — TERRESTRIAL ECOSYSTEMS
parently, the population of soil or-
ganisms recovers rapidly after burn-
ing and is associated with the increase
in nitrogen. In the top four centi-
meters of mineral soil in the South
Carolina study, over four grams of
nitrogen per hectare per day were
fixed in the burned plots while only
0.2 grams were fixed in the unburned
plots. However, the individual sam-
ples from the burned plots ranged
from no nitrogen fixation up to 61
grams per hectare per day, for rea-
sons that were not evident.
Disease — A survey throughout
the South showed less Fomes annosus
root rot on burned areas. This dis-
ease spreads by growth of mycelia
in the forest floor, or aerially by
spores from the fruiting bodies. Con-
sequently, fire may tend to retard the
spread of the disease.
Use of Prescribed Burning
in the Timber Industry
Prescribed fire has been recom-
mended and widely used in the lob-
lolly pine range for control of under-
story hardwoods, site preparation for
seeding or planting, and for fire-
hazard reduction.
Prescriptions for safe burning have
been reasonably well developed by
research and experience. Favorable
conditions are: relative humidity of
40 to 60 percent; a wind steady in
direction but under ten miles per
hour at four feet above ground; and
litter moisture content of 5 to 20
percent. Burning is safest when these
conditions are first reached after a
rain of half an inch or more.
Backfires are preferred for areas
with heavy fuel because they burn
more slowly and less intensely.
Headfires are used where fuel is
light. Igniting the entire perimeter
of the area is poor practice, since
"hot spots" occur where fires from
different directions meet, resulting
in crown scorching and sometimes
killing trees.
For Understory Control — Because
the hardwood understory is a major
obstacle to re-establishment of the
pine stand after harvest, its control
has received a great deal of attention.
If hardwoods are allowed to grow
unchecked throughout a pine rota-
tion, site preparation for regenera-
tion is difficult and costly; often
requiring use of heavy machinery.
Periodic burning during the rotation
holds this understory in check, with
the burning interval determined by
the growth rate of the understory
sprouts. A prescribed fire will burn
hardwood stems up to about two
inches in diameter back to the
ground. Thus, the burning interval
may range from a few years up to
ten years, depending on site quality,
overstory density, and the species in
the understory.
Periodic burning for understory
control is usually done in the winter.
Summer burns are more difficult to
control with several years' fuel ac-
cumulation, and winter burning usu-
ally fits better into the over-all
schedule of seasonally determined
forestry operations. Winter fires do
not kill the rootstocks, so the popu-
lation of understory plants is not
reduced; in fact, the number of
sprouts is usually greater during the
first few years after the fire than
before.
In contrast to winter fires, summer
fires reduce the understory popula-
tion. When the parent stem is killed
or cut in the summer, especially near
the end of the spring flush of growth,
the sprouts are much weaker than
those arising from winter-killed
stems. Plants that are not vigorous
often die. Thus, two or three suc-
cessive annual summer fires virtually
eradicate the understory. This effect
can sometimes be used to prepare
loblolly pine stands for regeneration.
The first burn is made in winter to
lower the fuel level to the ground
and make subsequent summer burns
safe. Then, two or three summer
burns reduce the understory popula-
tion and leave a favorable seedbed.
With an adequate supply of seed, a
new stand is virtually assured.
Prescribed burning for understory
control apparently has no detrimental
effect on the growth of the overstory
pine stand. In South Carolina, even
ten successive annual summer fires
did not cause any reduction in growth
of the overstory. With heavier sur-
face soil, or on slopes where more
water would be lost through in-
creased runoff following burning,
growth of the overstory might be
reduced.
For Site Preparation — Fire is also
often used after harvest cutting for
site preparation. Logging breaks up
the litter and exposes mineral soil
on an appreciable portion of the
harvested areas, but much of the
forest floor and the understory re-
main undisturbed. Fires for seedbed
preparation after logging are most
effective in late summer, before pine
seedfall, because pine seedlings have
an even start with the competing
hardwood sprouts the following
spring.
Other benefits are realized from
periodic burning. The stand is es-
sentially "fire-proofed." Because of
greater ease of movement, the costs
of timber inventory, tree marking,
logging, and timber-sale supervision
are reduced. Perhaps more important,
the habitat for wildlife, particularly
deer, is improved. Without fire, the
browse plants grow beyond reach of
deer early in the life of the stand.
With periodic burning, especially in
winter, the browse supply is repeat-
edly replenished as the understory
is killed back to the ground and
promptly resprouts.
Use Outside the South — Pre-
scribed burning has been most widely
practiced in the South but is now
coming into use in other sections of
the country. In the Lake States, it
is used as a site-preparation measure
for jack- and red-pine regeneration
and for understory control in red
pine. The effects on vegetation seem
310
FOREST FIRE
to be much the same as they are in
the South. Sprouting of hardwood
species is greatly reduced by summer
fires, and several summer fires will
virtually eliminate hazel, the most
serious and widespread competitor of
pine regeneration in Minnesota.
Spring and fall burns are less effec-
tive and sometimes more erratic in
behavior.
Use of fire for seedbed preparation
in black spruce has been developed
through research and is now being
used on a limited scale. Mature
black spruce is cut in strips. The
strips are burned while the water
table is high. The slash and certain
mosses, which are a poor seedbed for
spruce, are eliminated and a favor-
able seedbed of burned peat is created
on most of the area. Clearcut blocks
are also seeded artificially following
prescribed burning.
In the West, fire is used mainly
in Douglas fir and pine types for
slash disposal after harvest cutting,
which also prepares the area for
seeding or planting.
Needs and Limitations of
Prescribed Fire
While fire is a very useful tool,
it requires great care to apply prop-
erly. Its effects are not known com-
pletely, even in the South, and it
has sharp limitations. It is applicable
for understory control only where
the overstory is resistant to fire,
which restricts its use for this purpose
to the hard pine types. It has some-
what wider applicability for site
preparation.
Use of fire in the management of
forests has been applied with vary-
ing results, some promising, some
disappointing. One of the main prob-
lems is in understanding the total
effects of burning in order to achieve
consistent results either for forest
reproduction or wildlife management.
To prescribe fire for specified re-
sults while avoiding damages to the
stand and site, much more informa-
tion is needed on the relation of fire
intensity to weather factors and fuel
conditions, and the effect of various
fire intensities on the vegetation and
soils. While research may show that
particular weather and fuel condi-
tions will produce a certain fire in-
tensity, such narrowly specified con-
ditions will occur only infrequently
and for limited periods. Thus, the
duration of the required weather and
fuel conditions determines the acre-
age that can be burned, which may
often be less than planned. In addi-
tion, fire intensity will vary with
vegetational and fuel types over the
burn areas, with corresponding varia-
tions in results. Because of these
limitations and variations, fire can
only be an imprecise tool at best.
Consequently, if fire is to be used,
information to prescribe it correctly
is essential.
Limitations of the Southern Expe-
rience — It is not safe to assume the
effects of fire on soils observed in
the South are applicable elsewhere,
for two reasons. The frequent past
burning in the South may be a factor
in the observed soil effects — any
pine area used to study fire effects
is likely to have been burned many
times in the past. And soils elsewhere
are not comparable to those in the
southern pinery. Even in the South,
however, the available information
comes from only a few studies in
limited localities. Consequently, the
effects of fire on erosion, soil struc-
ture, chemical characteristics, and
soil biology should be investigated
along with studies of vegetational
effects and development of techniques
wherever fire is to be used. Burning
undoubtedly releases mineral nutri-
ents contained in the forest litter, but
these might be largely lost on slopes
and deep sands. Very little is known
about fire effects on soil flora and
fauna beyond their immediate de-
struction in the burned portion of the
forest floor, yet they may be very
important in longer-term soil produc-
tivity and the health of the forest
vegetation.
It should be recogni . ver,
that burning for site prep;
done only once in the life ol
stand. In southern pines, a rotation
(time from establishment to harvest
of a timber stand) may be as short
as 20 or 25 years. In the North and
West, a rotation is much longer.
Burning for hardwood control during
the rotation is done more frequently
and the effects on soils may be more
important.
Effect of Smoke — An aspect of
prescribed burning that has only re-
cently been recognized is that smoke
is an effect that needs to be con-
sidered. Weather and fuel conditions
satisfying prescriptions for burning
may occur simultaneously over ex-
tensive areas and many fires may be
burning at the same time. Locally,
low-lying palls of smoke can reduce
visibility enough to make automobile
driving hazardous. People in the
vicinity may suffer physical discom-
fort. On a larger scale, one could
speculate that weather might con-
ceivably be affected by fire under cer-
tain atmospheric conditions. Smoke
particles might serve as condensation
nuclei, resulting in cloudiness, or the
smoke itself might accumulate at tem-
perature-inversion levels, obstructing
back radiation and changing tem-
peratures at ground level. Thus, the
effects of the smoke alone might pre-
clude prescribed burning in some
localities.
Needed Scientific Activity
Several aspects of fire ecology
should receive serious attention:
1. Effects of fire or burning are
long-range. Published reports
are often based on short-term
studies, both in management
and ecology. Long-term studies
with both ecological and man-
agement emphasis are needed.
2. There should be more integra-
tion of ecological and manage-
ment research. The two are of-
311
TART IX — TERRESTRIAL ECOSYSTEMS
ten separate schools of thought,
and their approaches, methods,
and results should be more
closely integrated so that man-
agement workers would benefit
and apply ecological informa-
tion and ecologists would be
made more aware of the pos-
sible applications, economics,
and practical potentials in-
volved.
3. Fire affects all aspects of the
biotic environment, and these,
too, must be investigated, in-
cluding: soil moisture, tem-
perature, texture, chemistry,
soil microorganisms and fauna,
seedbed conditions, recovering
vegetation including mosses,
herbs, shrubs, and trees, af-
fected animal populations, and
air and water pollution. Inter-
relationships among these are
important in understanding the
total effect of fire.
4. Application of findings from
one forest and soil type to an-
other are usually not practical,
and few generalizations can
be made. The total picture for
each type of situation must be
worked out separately.
There is need for a careful
review and analysis of work
done in both ecology and man-
agement areas to integrate find-
ings to date and avoid dupli-
cation of efforts, a fault of
present and past work.
312
5. POLAR ECOSYSTEMS
Polar Flora and Vegetation
The polar tundra with a perma-
frost base, as found in the high
arctic and antarctic, is one of the
most fragile types of world vegeta-
tion. As with any ecosystem, the
living components in the tundra —
the microorganisms, plants, and an-
imals — are in delicate balance with
their environment; any change in
the environment will result in some
changes in the composition and rela-
tionships of the living components.
Since the number of different types
of living organisms in the polar
tundra are much fewer than in other
ecosystems, even small changes often
cause drastic changes in the composi-
tion and relationships of the living
organisms. For example, depression
by heavy vehicles, overgrazing, or
trampling by animal herds or humans
at certain times of the year can result
in complete local destruction of the
tundra vegetation. (See Figure IX-15)
Recovery to the original vegetation,
if it occurs at all, takes at least 100
years.
In the arctic, economic develop-
ment has already begun and is likely
to increase significantly in the future.
It is very important that the effects
of these developments on the fragile
tundra be studied by trained scien-
tists so that an assessment may be
made as changes take place. In the
antarctic, the only threat to the tun-
dra is from base construction and
tourism; these threats have thus far
been moderated by the provisions
and recommendations of the Antarc-
tic Treaty relating to conservation of
antarctic fauna and flora.
Because it appears to be much sim-
pler than the biological systems of
the temperate and tropical regions,
the polar tundra offers unique oppor-
tunities for studying problems in-
volving the interrelations between
the environment and the living or-
ganisms. This simplicity in appear-
ance results from the lack of large
trees, which in other regions make
for a distinct multi-level system (the
ground, the herb layer, the shrub
layer, and several tree-top layers)
with many different types of dwelling
places for other organisms. In the
polar regions, the levels are few,
and thus there are fewer complica-
tions involved in studying any one
of them. Despite this relative sim-
plicity, however, it does not neces-
sarily follow that the processes or
interrelations within the tundra are
any easier to understand than those
in a temperate or tropical forest.
Recent Developments in
Polar Studies
In the antarctic, except for areas
of the northern Antarctic Peninsula,
the tundra is the most depauperate
type, composed entirely of nonflower-
ing plants, mostly lichens, mosses,
and algae. Even where this tundra is
present, it is very spotty, dependent
primarily on the availability of water
in a land where desert conditions
prevail and where most of what
water there is is unavailable to plants
because it is frozen into snow and
ice.
The more humid northern Antarc-
tic Peninsula and the sub-antarctic
Figure IX-15 — A SECTION OF THE TUNDRA BIOME
The photograph shows a section of tundra or marshy plain near Point Barrow,
Alaska. The land is characterized by a lack of trees and an upper surface that is
spongy and uneven due to the freezing and thawing of the poorly drained land.
The picture shows polygons that are 15 to 25 feet across, a result of winter freezing.
Beneath the surface, at depths ranging from a few inches to several feet, is the
permafrost, or permanently frozen soil, that is the ultimate limit to plant root growth.
313
PART IX — TERRESTRIAL ECOSYSTEMS
islands have a tundra more nearly
resembling that of the arctic, but
containing fewer types of flowering
plants. There are only two species of
flowering plants native to the Ant-
arctic Peninsula.
The antarctic tundra has been less
studied than that of the arctic. How-
ever, as a result of the Antarctic
Treaty and the international scientific
cooperation of the past ten years,
great strides have been made in gath-
ering details about the plants and
their environments.
Major works have been written or
are in the process of being written
about flowering plants in all parts of
the arctic (Siberia, Scandinavia, and
central Canada). Work on the non-
flowering plants is less extensive but
is also progressing. A good begin-
ning has been made in the under-
standing of the plants that occur in
the antarctic as well. Major flora of
the various plant groups — lichens,
mosses, and algae — will probably
be reported on in the near future.
The flora of the sub-antarctic islands
are also being studied, and, again,
reports on major flora are likely to
appear relatively soon.
Thus, it can be said that much of
the basic investigation about polar-
region plant life is done or soon will
be. This cannot be said about the
interrelations among the plants and
animals and their environments. Tliis
is the needed area for study.
Needed Scientific Activity
Although, as noted, we know a
fair amount about the distribution
of the plants and animals in the
tundra, we lack detailed information
about all of the interrelationships.
Ecosystem modeling, a way of math-
ematically taking into account the
various factors of the environment
and their interrelationships with the
living organisms, requires such de-
tailed information for each com-
ponent of the model. Once a
meaningful model has been made,
predictions can be soundly based.
(See Figure IX-16)
The Tundra Biome study group of
the International Biological Program
has proposed that such things as
productivity of the plants and of the
whole tundra be investigated. Multi-
disciplinary studies of the sort that
have been done at Cape Thompson
and Kodiak Island in Alaska would
be valuable in providing a better
understanding of the tundra ecosys-
tem. There is need to study the
ecological interrelationships and the
specific changes that are being
brought about bv planned environ-
mental change. Only then will it
be possible to predict meaningful
changes that are likely to occur when
other environmental changes are
made.
314
ECOSYSTEMS
Figure IX-16 — FLOW DIAGRAM OF A WET COASTAL TUNDRA ECOSYSTEM
Numerals
replacing
flow lines
1— To carcasses
2 — To feces
3— To plant litter
A — To saprovores
5 — To soil organic
matter
6 — To available
soil nutrients
Snow
Process names
C— Consumption
D — Leaching and decay
M— Migration and dispersal
P— Photosynthesis
S— Solar heat
T— Translocation
U— Uptake
•—To aquatic system
Soil
unfrozen
moisture
Depth
of
thaw
Nonvascular
above
ground
Nonvascular
below
ground
M -
1,2 ■
Dicots
above
ground
Dicots
below
ground
TTT
1,2
>
Available
soil
nutrients.
Longspurs
Saprovores
Monocots
above
ground
Monocots
below
ground
i i
Frozen
edible
Standing
dead
LF
Soil
organic
matter
M
1,2
Carnivorous
arthropods
7
Plant
litter
Soil
micro-
organisms
II
This is a rather detailed flow chart of a tundra ecosystem representative of the Point
Barrow area. The driving variables (shaded areas) are solar heating, moisture
availability, nutrient availability, and photosynthesis. The net result is seen as the
production and maintenance of such animal populations as weasels, shorebirds, etc.
Although the diagram is basically an energy-related chart, the rates of flow of
energy between points are not indicated.
315
PART X
ENVIRONMENTAL
CONTAMINANTS
EFFECTS OF ENVIRONMENTAL
POLLUTANTS AND EXPOSURES ON
HUMAN HEALTH AND WELL BEING
In addition to their often profound ecological implications, man's activities and
their by-products have negative as well as positive effects on human health and well
being. In some cases, these effects are long-term and only now are beginning to be
understood; in other cases, effects are suspected but not yet proved; and in still
others, effects as yet unsuspected may exist. The charts below outline the situation
as it is at present; however, the current climate of environmental concern is apt to
lead to research that will document and modify this outline rather than expand it.
The following listings have been made available through the courtesy of the
World Health Organization.
COMMUNITY AIR POLLUTION
(Note: Items in parentheses refer to effects other than those directly affecting human health status)
Agents, pollutants
Definite Effects
Possible Effects
Sulfur dioxide (effects of
sulfur oxides may be due to sulfur,
sulfur trioxide, sulfuric
acid or sulfate salts)
Sulfur oxides and particulate
matter from combustion sources
Particulate matter
(not otherwise specified)
1. Aggravation of asthma and chronic
bronchitis
2. Impairment of pulmonary function
3. Sensory irritation
4. (Effects on vegetation)
6. Short-term increase in mortality
7. Short-term increase in morbidity
8. Aggravation of bronchitis and
cardiovascular disease
9. Contributory role in etiology of
chronic bronchitis and emphysema
10. Contributory role to respiratory
disease in children
12. Impairs visibility (soils surfaces
and materials)
13. (Alteration in incident sunlight)
5. (In certain conditions, produces
effects on buildings and works of art)
11. Contributory role in etiology of
lung cancer
14. Increase in chronic respiratory
disease
319
PARI \ - ENVIRONMENTA1 CONTAMINANTS
COMMUNITY AIR POLLUTION (continued)
Agents, pollutants
Definite Effects
Possible Effects
Oxidants (including ozone)
Ozone
Carbon monoxide
Nitrogen dioxide
Lead
Hydrogen sulfide
Mercaptans
Fluorides
15. Aggravates emphysema, asthma, and
bronchitis
16. Impairs lung function in patients
with bronchitis-emphysema
17. Eye and respiratory irritation and
impairment in performance of
student athletes
18. Increased probability of motor-
vehicle accidents
20. Irritant to respiratory tract
21. Impairs lung function
23. Impairs oxygen transport function
27. (Discolors atmosphere)
30. Increased storage in body
31. (Lethal to animals eating
contaminated feed)
34. Increased mortality from acute
exposures
35. Causes sensory irritation
36. (Damages property (paint))
39. Sensory irritation (odor)
41. (Damages vegetation; harms animals)
19. Alteration of oxygen consumption
22. Acceleration of aging, possibly due
to lipid peroxidation and related
processes
24. Increased general mortality and
coronary mortality rates
25. Impairment of central nervous
system function
26. Causal factor in atherosclerosis
28. Factor in pulmonary emphysema
29. Impairment of lung defenses such as
mast cells and macrophages or
altered lung function
32. Impairment of hemoglobin and
porphyrin synthesis
33. Probably decreases enzyme level
37. Impaired sensory detection or
reflexes
38. (Socio-cultural nuisance)
40. Headache, nausea, and sinus
affections
42. Fluorosis of teeth
320
COMMUNITY AIR POLLUTION (continued)
Agents, pollutants
Definite Effects
Possible Effects
Ethylene
Asbestos
Chlorinated hydrocarbon
pesticides
Organo-phosphorus pesticides
Other odorous compounds
Hydrothermal pollutants
Beryllium
Air-borne microorganisms
43. (Damages vegetation and hastens
ripening of fruit)
44. Produces pleural calcification*
45. Malignant mesothelioma, asbestosis*
47. Stored in body, mostly from milk
and animal fats
48. (Ecological damage)
50. Acute fatality
51. Acute illness
52. Impair cholinesterase
54. Sensory irritation
56. (Can influence local climate and
interfere with visibility)
58. Berylliosis with pulmonary impairment
59. Air-borne infections
46. Contributes to chronic pulmonary
disease (asbestosis and lung cancer)
49. Impairment of learning and
reproduction
53. Impairment of general health, and
of adaptation
55. Headache and sinus affections
57. (Influence on action of hydroscopic
pollutants)
* These effects have been shown to occur in the vicinity of mining and processing operations. General community exposure may cause these
effects, but this has not definitely been proven.
321
PART X — ENVIRONMENTAL CONTAMINANTS
FOOD AND WATER CONTAMINANTS
Agents, pollutants
Definite Effects
Possible Effects
Bacteria
Viruses
Protozoa and metazoa
Metals
Nitrates
and/or phosphates
and/or organic matter
"Softness" factor
Sulfates and/or phosphates
Dissolved solids
Fluorides
Chlorinated hydrocarbon
pesticides
Oil-petroleum
Thermal (heat) pollution
Phenols
1. Epidemic and endemic gastro-intestinal
infections (typhoid, cholera, shigellosis,
salmonellosis, leptospirosis, etc.)
2. (Malodor)
4. Epidemic hepatitis, and other viral
infections
6. Amoebiasis, schistosomiasis, hydatidosis
and other parasitic infections
7. (Malodor)
8. Lead poisoning
9. Mercury poisoning (through food chains)
10. Cadmium poisoning (through food chains)
11. Arsenic poisoning
12. Chromium poisoning
15. Methemoglobinemia (with bacterial
interactions)
18. (Eutrophication)
19. (Malodor)
21. Gastro-intestinal hypermotility
22. Impaired potability
23. (Impaired value for irrigation and
industry)
24. Fluorosis of teeth when in excess
25. (Ecological damage)
26. Impaired potability
27. (Ecological damage)
28. Impaired potability
3. Secondary interaction with
malnutrition and with nitrates
in water (cf., No. 15)
5. Eye and skin inflammation from
swimming
13. Epidemic nephropathy
14. "Blackfoot" disease
15. Methemoglobinemia (bacterial
interaction not required)
17. Nitorsamine effects on mutagenesis
and/or carcinogenesis
20. Increase in cardiovascular disease
322
LAND POLLUTION
Agents, pollutants
Definite Effects
Possible Effects
Human excreta
Sewage
Garbage
Industrial and radioactive
waste
Fertilizers
Pesticides (food chain)
1. Schistosomiasis, taeniasis hookworm,
and other infections
2. Urban filariasis
3. Flies and other vectors
4. Odor
5. Rat and other rodent infestation
6. Flies and other vector-transmitted
diseases
7. Odor
8. Pollution of water and air from
disposal practices
10. Storage and effects from toxic
metals and other substances through
food chains
11. (Loss of vegetation and soil, and
altered ecology)
12. Ground water pollution effects,
surface water pollution effects
13. Contamination of vegetation and
secondary foodstuffs
9. Typhus, plague, leptospirosis, and
other infectious diseases
323
PART X — ENVIRONMENTAL CONTAMINANTS
THERMAL EXPOSURES
Agents, pollutants
Definite Effects
Possible Effects
Cold damp
Cold dry
Hot dry
Hot damp
1. Excess mortality from respiratory
disease and fatal exposure or
frostbite
3. Excess morbidity from respiratory
disease and morbidity from frostbite
and exposure
5. Mortality from frostbite and
exposure
7. Morbidity from frostbite and
respiratory disease
8. Heat-stroke mortality
9. Excess mortality attributed to
other causes
10. Morbidity from heat stroke and
excess from other causes
11. Impaired function; aggravation of
renal and circulatory diseases
12. Increase in skin affections
14. Heat-exhaustion mortality
15. Excess mortality from other causes
16. Heat-related morbidity
17. Impaired function
18. Aggravation of renal and circulatory
disease
2. Contributes to excess mortality and
morbidity from other causes
4. Rheumatism
6. Impaired lung function
13. Increase in prevalence of infectious
agents and vectors
324
RADIATION AND MICROWAVES
Agents, pollutants
Definite Effects
Possible Effects
Natural sunlight
Diagnostic X-ray
Therapeutic radiation
Industrial uses of radiation
and mining of radioactive ores
Nuclear power and reprocessing
plants
Microwaves
1. Fatalities from acute exposure
2. Morbidity due to "burn"
3. Skin cancer
4. Interaction with drugs in
susceptible individuals
7. Skin cancer and other skin changes
10. Skin cancer
11. Increase in leukemia
12. Acute radiation illness
16. Acute accidental deaths
17. Radiation morbidity
18. Uranium nephritis
19. Lung cancer in cigarette-smoking
miners"
20. (Effects on food chains)
22. (Ecological damage due to thermal
pollution of water)
23. Storage of potentially harmful
materials in the body
24. (Radioactive contamination of air,
land, and water)
5. Conditional exacerbation in porphyria
6. Increase in malignant melanoma
8. Contributing factors to leukemia
9. Alteration in fecundity
13. Increase in other cancers
14. Acceleration of aging
15. Mutagenesis
21. Increase in adjacent community
morbidity
25. Increase in cancer incidence
26. Community disaster
27. Alteration in human genetic material
28. Tissue damage
■ While this is an occupational exposure, its interpretation is of great importance for community health protection.
325
PART X — ENVIRONMENTAL CONTAMINANTS
NOISE AND VIBRATIONS
Source
Definite Effects
Possible Effects
Traffic
Aircraft (including sonic
boom)
Recreational
Official (bells, sirens)
Technological— building
construction, paving, etc.
Domestic noise
Vibrations
1. Temporary loss of hearing
2. Impairment of rest and communication
3. Sensory irritation
8. Permanent hearing loss
9. Temporary hearing loss
10. Impairment of rest
11. Impairment of communication
12. (Damage to property)
14. Temporary hearing loss
15. Interference with rest
16. Interference with communication
17. Sensory irritation
19. Temporary loss of hearing
20. Sensory irritation
21. Temporary hearing loss
23. Impairment of rest and
communication
25. Discomfort
4. Progressive hearing loss
5. Increased social disorganization
6. Contributory to cardiovascular disease
7. Impairment of circulatory function
13. Aggravation or cause of mental illness
18. Aggravation of tension-related
conditions
22. Progressive hearing loss
24. Produces tension
26. Articular and muscular disease
27. Adverse effects on nervous system
326
HOUSING AND HOUSEHOLD AGENTS
Agents, pollutants
Definite Effects
Possible Effects
Heating and cooking
Fumes and dust
Crowding
Structural factors (including
electrical wiring, stoves,
and thin walls)
Paints and solvents
Household equipment and
supplies (including
pesticides)
Toys, beads, and painted
objects
Urban design
Acoustical factors
1. Acute fatalities from carbon
monoxide, fires and explosions,
and discarded refrigerators
3. Acute illness from fumes
4. Impaired oxygen transport
5. Aggravation of asthma
8. Spread of acute and chronic disease
9. (Impairment of social interaction
and of privacy)
10. Accidental fatality
11. Accidental injury
12. Morbidity and mortality from lack of
protection from heat or cold
13. Morbidity and mortality due to fire
or explosion
14. (Impairment of privacy)
16. Childhood lead-poisoning fatalities,
associated mental impairment and
anemia
17. Renal and heptic toxicity
18. Fatalities and morbidity from fire
20. Fatalities from fire and injury
21. Morbidity from fire and injury
22. Fatalities from poisoning
23. Morbidity from poisoning
24. Mortality and morbidity
25. Increased accident risks
26. (Social disruption and isolation)
28. Impairment of rest and sleep
2. Increase in diseases of the
respiratory tract in infants
6. Increase in chronic respiratory
disease
7. Increase in heart disease
15. Mental illness and behavioral
disorders
19. Acute effects of other vapors
and paints
27. Psychological effects from lack
of diversity, accessibility,
recreational areas
29. Possible aggravation of tension-
related conditions
327
1. AIRBORNE CHEMICALS
Chemical Contaminants in the Atmosphere
Atmospheric contamination is dif-
ficult to define precisely, since "pure
air" itself is a mixture. Water con-
tamination is a simple concept, since
"pure water" is a single chemical sub-
stance. Even with human influences
absent, the air has a variable compo-
sition in both time and space. There
is evidence that there was more oxy-
gen in the atmosphere at the peak of
the carboniferous era than there is
today; and the atmosphere close to
an erupting volcano is bound to be
different in composition from the air
in the midst of a pine forest.
Definition of Contamination
To discuss the contamination of a
mixture it is necessary to define an
arbitrary composition as "pure." It is
usual to define dry pure air as con-
taining roughly 78 percent nitrogen,
21 percent oxygen, 0.03 percent car-
bon dioxide, and the remaining 0.97
percent noble gases. (See Figure X-l)
Water vapor is present in pure air in
highly variable amounts.
Under this definition, all air is con-
taminated to some degree. Much of
the contamination is both natural and
beneficial. The development of clouds
and precipitation, for example, re-
quires the presence of "nucleation
centers," usually consisting of dust,
sea salt, and particles formed in the
air by reactions between gaseous
contaminants.
Some contaminants are intrinsically
harmful to things that humans value
or harmful in excessive concentra-
tions. If these contaminants are pro-
duced directly or indirectly by human
Figure X-1 — COMPOSITION OF CLEAN, DRY AIR
Component
Content
%by
volume
ppm
Nitrogen
78.09%
780,900 ppm
Oxygen
20.94
209,400
Argon
.93
9,300
Carbon
dioxide
.0318
318
Neon
.0018
18
Helium
.00052
5.2
Krypton
.0001
1
Xenon
.000008
0.08
Nitrous
oxide
.000025
0.25
Component
Content
%by
volume
ppm
Hydrogen
.00005%
0.5 ppm
Methane
.00015
1.5
Nitrogen
dioxide
.0000001
0.001
Ozone
.000002
0.02
Sulfur
dioxide
.00000002
.0002
Carbon
mon-
oxide
.00001
0.1
Ammonia
.000001
.01
The table shows the major and some of the trace constituents of clean, dry air
near sea level. The concentrations of some of the gases may differ with time and
from place to place. Some of the data are open to question, but the values are
meant to indicate the order of magnitude.
activities, they are called air pollut-
ants. In a few instances a pollutant
is not, paradoxically, a contaminant.
For example, excessive industrial
steam meets the usual criteria of a
pollutant if it obscures visibility on
a major highway; yet strictly speak-
ing it is no more than a part of the
variable fraction of water vapor as-
cribed to "pure" air.
The distinction between a harmful
contaminant and a pollutant may be
a narrow one. Natural contamina-
tions, such as a rain of volcanic ash
or a desert sandstorm, are not classed
as pollutants. But when human ac-
tivity is responsible for their occur-
ring — as it was in the great dust
storms of the 1930's — these contami-
nants are classed as pollutants. We
can legitimately consider even a sand-
storm in the Sahara as pollution,
since the great desert, at least in its
present extent, appears to have been
caused by overgrazing.
A final case needs to be distin-
guished in the definition of contami-
nation. Air may be rendered harmful
to life, not by the presence of con-
taminants, but by the absence of
oxygen. Since combustion within the
48 contiguous United States now re-
quires twice as much oxygen as all
the green plants in the area produce,
the hazard of depleted air may be-
come acute.
The Environmental Problem
The sources of pollutants are gen-
erally well characterized and the com-
position of most is known. Much less
is known about natural contaminants.
Many come from enormous areas at
miniscule concentrations. For exam-
ple, air that blows into Barbados
from the tropical Atlantic contains a
329
PART X — ENVIRONMENTAL CONTAMINANTS
minute trace (about one part in two
billion parts of air) of sulfur diox-
ide. In spite of all the sulfur diox-
ide put into the air by burning high-
sulfur fuels, it is unlikely that any
of this human contribution reaches
Barbados. Instead, some natural,
probably maritime, source must be
responsible for maintaining the con-
centration at this level.
It is possible to compute how much
carbon monoxide the industries and
automobiles of the world release into
the atmosphere, and it appears that
the worldwide concentration of this
gas is about one part in ten million.
Knowing these facts, it should be
possible to estimate how rapidly car-
bon monoxide is removed from the
air. However, it has recently been
discovered that the ocean also con-
stitutes a vast and diffuse source of
the gas; thus a much higher removal
rate must account for the known con-
centration. At present the removal
process is unknown, yet it must be
discovered if environmental manage-
ment is to be possible. A knowledge
of the lifetime of carbon monoxide in
air would be a valuable clue from
which to begin.
Over-all, one fact is clear. Many
pollutants are also released naturally,
though at lower concentrations. If
there were no natural processes to
remove them, the atmosphere would
be far more heavily contaminated
than it is, even in the absence of
human contributions. Hence there
must exist an enormous complex of
processes which maintain the atmos-
phere at substantially its present
composition. Every component, even
most of the minor ones here called
contaminants, is present in the global
atmosphere as a result of closely bal-
ancing processes of generation and
removal.
These processes are such that a
substantial increase or decrease in
generation will be rapidly counter-
acted, at least in part, by a corre-
sponding change in rate of removal.
However, this sort of feedback con-
trol generally has its inherent limits.
A very simple example is the ability
of living vegetation to remove sulfur
dioxide from the air. Studies in
Panama show that a very small con-
centration of this gas is a natural
contaminant in the tropics, perhaps
emanating from decayed vegetation.
If this supposition is correct, then the
small natural concentration of sulfur
dioxide results from a balance of its
release from dead plants and its con-
sumption by living plants.
The balanced system will accom-
modate a considerable input of sulfur
dioxide from pollutant sources, and,
in fact, the gas has been shown to
absorb rapidly into vegetation. If the
added input is too great, however,
plants perish, and the system fails.
It is further obvious that all forms
of life release wastes to the environ-
ment. Wastes by definition are in
some degree toxic to the organisms
that excrete them; hence, man or any
other organism reaching an intoler-
able population density will pollute
the environment with respect to his
own survival. Man is far worse than
his numbers indicate because he aug-
ments his own energies by the syn-
thetic release of energy, thus gener-
ating additional wastes. The energy
generated in the United States alone
is equal to that of 100 billion humans.
These "equivalent energy slaves" are
a measure of our standard of living;
they are also a true measure of our
impact upon the environment.
Clearly, no acceptable degree of
control is imminent for the human
population. If both world population
and the U.S. living standard were
frozen at present levels, and the rest
of the world raised to the U.S. stand-
ard, a tenfold increase in pollutant
emissions would result, assuming con-
stant technology. Yet population can-
not be stabilized overnight, and the
rest of the world does aspire to the
U.S. living standard; although con-
stant technology is a poor assump-
tion, the developing countries have
shown little inclination to avoid the
environmental errors of our own past.
These collective considerations de-
lineate the environmental problem.
The human impact has reached an
alarming level, and much of its force
is mediated by the atmosphere. (See
Figure X— 2) Beyond the above quali-
tative statement, what is the state of
our knowledge?
State of Scientific Knowledge
Frankly, our over-all knowledge is
extremely fragmentary. Pate, Lodge,
and their co-workers at the Na-
tional Center for Atmospheric Re-
search have reported on atmospheric
composition in the moist tropics in
regions far from pollution sources.
Keeling and several others continue
to measure worldwide distributions
of carbon dioxide. At the Stanford
Research Institute, Robinson and
Robbins have obtained apparently
reliable figures for the worldwide
concentration of carbon monoxide,
and have shown the presence of an
unsuspected natural source of this
gas in the ocean. Patterson and his
group at the California Institute of
Technology, by analyzing ice cores
from the Greenland Ice Cap and
from Antarctica, have documented
the worldwide secular increase in
atmospheric lead. All of this infor-
mation is necessary to assess the orig-
inal state of the system that mankind
is now disturbing.
O'Keeffe and his colleagues in the
Environmental Protection Agency,
Axelrod, Lodge, and others at the
National Center for Atmospheric Re-
search, and numerous academic sci-
entists are gradually developing ana-
lytical methods of sufficient sensitiv-
ity, specificity, and reliability to
assess both the reputedly unpolluted
and polluted environment. At the
University of Washington, Charlson
has developed a nephelometer that
rapidly assesses local atmospheric
haziness and also makes possible
330
EMICALS
Figure X-2 — POLLUTION — AN ENVIRONMENTAL PROBLEM
The picture illustrates the multiple problems of pollution encountered in a small
city in western Pennsylvania. In the first instance, the gaseous effluents from the
industrial complex form a cloud over and downwind of the city. This cloud, in
addition to causing changes in the local radiation balance and possibly other local
changes, is composed of water vapor mixed with pollutants such as sulfur dioxide
that cause damage to plants, animals, and man. The city is located on a river
into which industrial and municipal wastes are dumped; in earlier days there was
no need to worry about the consequences of such action and now, although funds
are becoming available to help build water-treatment plants, it is difficult to keep
up with the need. The question of solid waste disposal presents yet another
unsolved problem. The original city dump along the river only makes the water
pollution worse. Incineration causes air pollution. Sanitary land fills use up large
quantities of desirable land. Shipping the wastes by rail or barge may help the
local problem but does not eliminate it. Furthermore, all these problems spill over
into downwind or downstream localities.
laboratory experiments on haziness
modification. He has shown that in
many typical atmospheres the tur-
bidity measured by his instrument
correlates closely with the mass of the
particles present.
The Environmental Protection
Agency (EPA) maintains monitoring
and surveillance activities in most of
the major U.S. cities, and some local
agencies are measuring their own pol-
lution problems. However, most of
the widely used techniques are five to
twenty years old and are less effec-
tive than most recently developed
methods. Nearly all of them lack
precision and specificity, and thus the
results are affected significantly by
the presence of pollutants not being
measured.
The Measurement Problem — Be-
fore newer techniques are accepted,
verifiable standards need to be estab-
lished for precision, specificity, and
accuracy in measuring pollutants at
concentrations as low as one part in
a billion parts of air and in the pres-
ence of equal or larger amounts of all
other possible pollutants. This meas-
urement problem is not only unre-
solved, but there has been no agency
with the explicit and exclusive re-
sponsibility for evaluating proposed
analytical methods. Only recently
has a group been created with the
responsibility of evaluating existing
methods of atmospheric analysis, and
it is not yet certain to what extent
this group will be successful. Mean-
while, there is a strong tendency to
use old techniques, which at least
provide numbers, even thougl
may be some uncertainty as to the
physical meaning of those numbers.
Neio Attitudes — The immediate
past has seen remarkable changes, not
so much in the state of knowledge
as in the state of mind of the at-
mospheric research community. Not
many years ago, an announcement of
plans to study atmospheric chemistry
in the tropics invited accusations of
junketing from one's colleagues. Only
a short time past, many scientists felt
that usefulness tainted research re-
sults; today "relevant" research topics
are eagerly sought by formerly "pure"
scientists.
New Methods — Older research
tools have been improved and simpli-
fied and new tools have been devised.
Gas chromatography with more sensi-
tive detectors, atomic absorption, neu-
tron activation, chemiluminescence
and fluorescence quenching — all these
and others provide the means to ana-
lyze even smaller, more dilute, and
more complex samples.
This combination of new methods
and progressive attitudes in environ-
mental study summarizes the current
status of trace chemistry of the atmos-
phere. While recent achievements are
not great, there is now an expectancy
and readiness for major scientific ad-
vances in this field.
Needed Scientific Activity
This mood of expectancy has led
no fewer than a half dozen groups
around the world to examine the pos-
sibility of routine monitoring of sev-
eral major contaminants in the air.
Carried out at sites remote from local
pollution, such work could provide
for the first time true "benchmark"
measurements against which future
changes in the atmosphere can be
gauged. Recently, a number of groups
within the United States independ-
ently concluded that a saturation
study is needed of pollution in a
single city, ranging from the point
331
PART X — ENVIRONMENTAL CONTAMINANTS
of individually emitted pollutants to
the far downwind zone where pollu-
tants merge with the general atmos-
phere.
Studies of (a) urban pollution, (b)
analytical methods, and (c) laboratory
models of reactions producing, alter-
ing, and removing contaminants are
three areas of atmospheric chemis-
try that require immediate attention.
These studies alone are not sufficient,
however, to solve the environmental
problem. Supporting work needed in
the biological sciences is lagging for
lack of precise methods to assess the
ecological impact of contaminants;
there must be innovation in city plan-
ning, architecture, engineering, and
related fields; and behavioral research
is essential to understand why people
elect to pollute and how they may
be dissuaded from polluting. With
population increase, restraints inevi-
tably increase; acceptance of these re-
straints will be necessary to preserve
and nourish other freedoms.
Atmospheric Contaminants and Development of Standards
Atmospheric contamination can be
considered on the global, national,
state, regional, and local scales, each
of which has its own vertical and
temporal scales. (See Figure X— 3) The
temporal scales have two aspects —
the time-scale of the adverse effects
associated with the contaminant, and
the time-scale required for effective
action for its control. These two time-
scales tend to be similar in magni-
tude for each of the horizontal scales
noted above.
One example of the global system
is the postulated effects on the earth's
temperature when carbon dioxide and
particulate matter build up in the at-
mosphere, affecting global heat bal-
ance. Another example is fallout from
testing of nuclear weapons in the at-
mosphere. Neither of these problems
can be resolved unilaterally by any
one nation. Hence the time-scale for
resolution is that of action by inter-
national organizations.
On the national scale, which in the
United States is synonymous with the
continental scale, we are concerned
with the buildup of the background
contaminant concentration of the non-
urban air mass and with interstate
transport of contaminants. Experi-
ence has shown us that these take
years to resolve.
Within the confines of a state, our
problems are those of urban-subur-
ban-rural contaminant transport and
reactions and of the impact of large,
single contaminant sources on the
land areas within their range of in-
fluence. In such matters, we would
expect a state to be able to initiate
controls, if not effectively accomplish
them, in a matter of months.
In the United States, we are com-
mitted to the regional concept of air-
pollution control — the region being
generally a multi-county area, either
intra- or inter-state, which contains
the principal sources of its pollution
and the principal receptors adversely
affected thereby. The principal time-
scale with which a region must con-
cern itself is the so-called air-pollution
Figure X-3 — ATMOSPHERIC SCALES
Horizontal Scale
Vertical Scale
Temporal Scale
Global
The Atmosphere
Decades
National
The Stratosphere
Years
State
The Troposphere
Months
Regional
The Lowest Mile
Days
Local
The Height of
Buildings
Hours
"episode" — the build-up of pollution
during a stagnation of horizontal and
vertical atmospheric transport mecha-
nisms extending over a matter of sev-
eral days. Therefore, although the
region may adopt a larger time-scale
for attack on the basic causes of its
contaminant problem, it must also
be prepared to react to an occurring
episode on a same-day or next-day
basis.
The smallest scale is that of the
locality, covering several city blocks,
in which traffic builds up for several
hours each morning and afternoon.
Our concern for atmospheric con-
tamination globally is for the integrity
of the earth as a planet on which hu-
man life can exist without extinction
by freezing, overheating, inundation,
or starvation. Nationally, regionally,
and locally we see atmospheric con-
tamination as having adverse effects
on our health, on vegetation, livestock,
materials, structures, and the atmos-
phere itself. All these elements of
damage are associated with costs to
society and to our economy; and all
the means for control of contaminants
have within them certain inherent
costs. Our general view is that it costs
us more to have pollution than to
control it.
Measuring Air Quality
If one views air pollution as a sys-
tem (see Figure X-4), we find that a
convenient starting point is "Sources
and Their Control." Our knowledge
of the principal pollution sources and
332
AIRBORNE CHEMICALS
Figure X-4 — A SYSTEM FOR DISCUSSING AIR POLLUTION
STRATEGY FOR
MR POLLUTION CONTROL
SOURCES Al
POL
TACTICS FOR
EPISODE CONTROL
ID THEIR CONTROL
AND THEIR EFFECTS
i
t
AIR
QUALITY
STANDARDS
EMISSION
STANDARDS
■
SOURCES
CONTROL
METHODS
▲
POLLUTANT
HALF-
LIFE
POLLUTANTS
EMITTED
EPISODE
CONTROL
TACTICS
i
1
i
i
' '
' i
• .
■ '
SOCIAL
AND
POLITICAL
CONSIDERATIONS
EMISSION
ALLOCATION
ALTERNATE
PRODUCTS
AND
PROCESSES
COST
FUNCTIONS
AIR QUALITY
TRANSPORT
AND
DIFFUSION
SOCIAL
AND
POLITICAL
CONSIDERATIONS
i
I
i
i
\ ■
' ■
i i
r~
AIR
QUALITY
CRITERIA
SOCIAL
AND
POLITICAL
CONSIDERATION
COST
EFFECTIVE-
NESS
DAMAGE
FUNCTIONS
AIR
POLLUTION
EFFECTS
ATMOSPHERIC
CHEMISTRY
AIR
^ POLLUTION
^ POTENTIAL
FORECASTS
S
'
'
The diagram shows a systems idealization of the problem of air pollution. Each
box represents a set of problems about which we may know something, but certainly
not enough to solve the problems or to understand exactly how that box may
interact with other boxes. It is interesting to note the role of social and political
considerations in the over-all air-pollution problem. They dominate our strategy
and tactics for the control of air pollution.
the means for their control is quite
good, particularly with regard to the
contaminants that are emitted to the
atmosphere in greatest annual ton-
nage — namely, carbon dioxide, car-
bon monoxide, SOx, NO,, hydrocar-
bons, and particulate matter. (In
air-pollution parlance SCX and NOs
mean a mixture of oxides.) Present
knowledge of emissions that occur in
lesser annual tonnage is less precise;
and our control technology is fraught
with economic problems.
Some of our apparent control tech-
nology has yet to be reduced to
commercial practice because of the
following dilemma:
1. Application of the untried tech-
nology would represent a cost
to the user that could be re-
covered only by raising the cost
of the product or service pro-
duced.
2. Raising the cost of the product
or service would adversely af-
fect the competitive positions of
the applier of the technology
and will therefore be resisted
unless required by law or sub-
sidized by government.
3. There is a reluctance to require
by law the application of an
untried technology.
This leaves governmental subsidy as
the means to introduce untried tech-
nology. As yet, we have made only
halting steps in this direction.
Once pollutants have been emitted,
we are concerned with their fate in
the atmosphere and the adverse ef-
fects they produce. Their life history
in the atmosphere starts with their
transport and diffusion from their
points of emission to their ultimate
receptors, during the course of which
they are subject to chemical reaction
in the atmosphere and a host of scav-
enging processes that tend to remove
them from the atmosphere. The result
of these several processes is measur-
able at any receptor point in terms of
the concentrations of the kinds and
forms of contaminants that survive to
reach the receptor.
What we measure at a receptor
point we call "air quality." Because
of seasonal, diurnal, and microscale
333
PART X — ENVIRONMENTAL CONTAMINANTS
variations in source strengths and
character and in transport, diffusion,
reaction, and scavenging factors, air
quality will show considerable vari-
ability. However, by increasing the
averaging time of air-quality data, we
can suppress enough of this variabil-
ity to interpret the data meaningfully.
Technological Shortcomings —
There are scientific shortcomings in
each stage of the process described
above. The transport and diffusion
phase takes place in the lower reaches
of the atmosphere, above most
ground-based instrumentation and be-
low most aircraft and satellite-borne
instrumentation. It occurs over popu-
lous areas and in airport traffic pat-
terns where we are not free to operate
balloons, drones, towers, rockets,
dropsondes, and other means of prob-
ing the atmosphere for meteorological
and pollution information. To the ex-
tent that much of our measurement
technology lacks sophistication, our
knowledge of the phenomenon meas-
ured falls short of the optimum de-
sired. Because of the complexity of
the potential chemical and scavenging
reactions among all the pollutants
present in the atmosphere, we have
only scratched the surface of under-
standing these phenomena.
Our knowledge of air quality is
limited, furthermore, to just a few
places on earth that have been able to
afford the installation and operation
of air-quality monitoring equipment.
Commercial vendors of such equip-
ment have tended to await demand,
with the result that there has been a
proliferation of instruments to meas-
ure a few well-publicized pollutants
and a paucity of instruments for
monitoring the less "popular" con-
taminants.
Data Base — We have given the
name "air-quality criteria" to tabula-
tions of cause-effect data relating var-
ious concentrations of contaminants
with the effects observed on people,
vegetation, livestock, materials, struc-
tures, and the atmosphere. These ob-
servations encompass studies in the
laboratory and the field and, in the
case of people, involve epidemiologi-
cal and clinical studies. Our "people"
data is the weakest because airborne
contaminants are only one class
among many of stresses on population
and the attribution of health effects
to any one class is very difficult. Since
these latter data form the basis for
establishment of "air-quality stand-
ards," and thus the base for regulatory
control, they are the most contro-
versial of all the data in the whole
field of air pollution.
The setting of "air-quality stand-
ards," and the derivative establish-
ment of "emission standards" to limit
the emission of specific classes of
sources, calls forth not only data from
the physical and biological sciences,
but also involves trade-offs and deci-
sions that deeply involve the social
and political sciences and interactions
with other elements of the ecological
and economic system. Decisions as to
how we control air pollution can af-
fect water and land pollution, and
vice versa. Decisions on pollutant
levels can affect the energy supply
for our economy and reflect on the
nationwide and worldwide trade in
fuels. Considerable public contro-
versy is likely, therefore, as to the
desirable uniformity of air quality
and national emission standards.
Modeling — To help resolve some
of these problems, mathematical mod-
eling is increasingly being applied,
both to the gross model of the whole
air-pollution system and to more de-
tailed models of individual elements
of the system as, for instance, the
transport and diffusion model. These
latter models have been used exten-
sively in setting the geographic
boundaries of the "air-quality control
regions" currently being designated
by the federal government in various
urban areas of the United States.
What We Need to Know
Data — More than anything else,
we need to know the effects of pol-
lutants in the atmosphere on the ex-
posed population. Much of our past
knowledge has been of the effects of
certain pure substances on experi-
mental animals or healthy adults.
What we need is knowledge of how
the mix of pollutants as they really
exist in the atmosphere affects the
actual mix of the exposed population.
Technology — Our greatest air-
quality measurement and monitoring
need is for remote means of probing
hundreds or thousands of feet through
the air for an information return of
pertinent chemical and physical data.
In the area of control technology,
our greatest need is to test prototypes
and pilot plants preparatory to pro-
duction and commercial action.
Air-Quality Management — Fi-
nally, we need better understanding
of air pollution as a system, of the
interaction within the system and be-
tween it and other systems in the eco-
logical and economic whole. In effect,
we need to learn how better to man-
age the air-quality system.
Institutional Resources — To do
these things requires trained people
and facilities in which to train them.
Much of the money that is now being
spent in contract research could be
better spent in building and equipping
facilities for air-pollution research and
training, preferably at universities, of
a type that does not now exist in the
United States. As an example, the
Japanese government has built several
large low-velocity wind tunnels for
air-pollution research; in the United
States, the federal air-pollution au-
thorities have built none. All the large
new smog chambers for the study of
atmospheric chemical reactions are in
the laboratories of private research
organizations; they are not available
for student training. The list could go
on and on. Clearly, a redirection of
effort is needed if tomorrow's prob-
lems are to be solved.
334
Modeling the Atmosphere
AIRBORNE CHEMICALS
The purpose of the models in ques-
tion is to allow quantitative assess-
ment of "air quality" — i.e., the con-
centration of pollutant gases and
particles — at all or chosen points
within an area of the order of 100
square miles which contains (and is
bordered by) numerous pollutant
sources. Models are required both for
the assessment of abatement tactics
(What sources are responsible for
what degree of pollution in what
areas?) and for the planning of de-
velopment (What will be the effect of
a new highway or new industrial com-
plex on pollutant concentrations in
the area and how, given that a pollu-
tant must be emitted, can its impact
be minimized by the siting of the
source?).
Existing models, when classified
only according to the nature of their
output, are of two types: short-term
models and long-term models. The
objective of a short-term model is to
compute air quality averaged over
periods of about one hour to one day.
Long-term models produce averages
of air quality over periods of one
month to one year. Statistics of short-
term averages of air quality may be
derived from the output of long-term
models by the application of empirical
distribution functions. Long-term
models are, therefore, applicable to
planning and to assessing the broad
impact of land-use changes on air
quality; but if models are to be used
in the day-to-day management of
air quality — e.g., during air-pollution
alerts and incidents — short-term
models are required. Long-term aver-
ages and statistics can, of course, be
derived by the repeated use of short-
term models, at the expense of com-
puting effort.
Physical and Mathematical
Basis of Air Quality Models
To compute the concentration of a
pollutant, we must know where and
in what quantity it is emitted and
what happens to it in the atmosphere.
If the source inventory is inadequate,
the model cannot be expected to be
adequate. An adequate source in-
ventory must account for the total
emission of pollutant over the area,
and it must have the same resolution
in time and space as the required out-
put of the models, so that if we re-
quire, for example, the one-hour aver-
age concentration of sulfur dioxide
(SO-) over an area one mile square,
we must have an inventory of emis-
sions of SOj hour by hour, averaged
over areas not greater than one mile
square.
Once in the atmosphere, the pol-
lutant travels with the wind. It may
react chemically with other pollutants
or normal atmospheric constituents,
it may fall out or be washed out, or it
may change by radioactive decay.
Traveling with the wind is conven-
tionally divided into transport by the
average wind (the average being taken
over times and areas larger than those
resolved by the model) and diffusion
by the turbulent eddies (i.e., by wind
variations on time or space scales
smaller than those resolved by the
model).
The mathematical basis of short-
term air-quality models is the so-
called continuity or conservation
equation — a balance sheet of the
pollutant in a box in space, with terms
representing transport in and out by
the mean wind, transport in and out
by turbulent diffusion, emissions on
the surfaces of and within the box
(i.e., the "source inventory"), and
chemical or radioactive transforma-
tion within and deposition out of the
box.
Specification of the mean wind, the
coefficients of diffusion terms, and
the nature of the transformation, de-
position, and decay is the task of the
atmospheric scientist. Efficient or-
ganization of the calculations calls
for mathematical and computational
skills. Solution of the continuity equa-
tion is essential for a rigorous compu-
tation of the concentration of pollu-
tants produced by chemical reaction,
such as the oxidants in photochemical
smog, but no such model of an exten-
sive area has yet been produced be-
cause of the computational complexity
of solving a set of simultaneous con-
tinuity equations. The short-term
models that have been successfully
applied have been based on formulae
that are formal solutions of a continu-
ity equation with diffusion terms.
Such solutions are typified by the
"Gaussian plume" distribution of ma-
terial continuity emitted by a point
source. This has the form
X(x,y,zJTL
2ttiJjUzu
exp
Mm
where X is the concentration of
pollutant at a height z, distant x in
a direction along the mean wind
and y in a direction across the mean
wind from a source at height H
emitting material at a uniform rate
Q into a mean wind of strength u.
The factors cry and o-Z/ which meas-
ure the diffusive dispersion of the
material in the horizontal and verti-
cal directions, depend both on the
meteorological conditions and on
the distance from the source. They
have been determined empirically
many times and standard tables
exist.
Various integrations of this formula
adapt it for use with line sources and
335
PART X — ENVIRONMENTAL CONTAMINANTS
sources distributed uniformly over an
area. Current air-quality models ap-
ply these formulae to all the sources
that contribute to the concentration
within the chosen "target area" at the
chosen time. They differ in the meth-
ods by which they insure that only
the essential minimum of computation
is carried out.
Performance of Air
Quality Models
The Gaussian-plume formula has
been tested in many field trials in
carefully observed weather conditions
with controlled sources of a conserved
pollutant. Using the standard meth-
ods of estimating the diffusion param-
eters of <r, and az, it is found that the
formulae yield concentrations that are
within a factor of 2 of the observed
concentrations in about 75 percent of
trials.
An elaborate short-term air-quality
model has been constructed for the
state of Connecticut, with the sources
of four pollutants specified for areas
5,000 feet square and two-hour time
resolution for four seasons of the
year. There are approximately 5,000
separate sources and the program al-
lows computation of two-hour aver-
age concentrations of each pollutant
over any or all of the squares. In
specially conducted trials over 25 days
with measurements at 30 points, it
was found that 45 percent of the com-
puted two-hour average concentra-
tions of SOl' were within a factor of
2 of the measurement at a point with-
in the 5,000-foot-square box. Meas-
urement of the average concentration
over a 5,000-foot square is not prac-
ticable, but statistical examination of
the space variability of concentration
suggested that the output of the model
would be within a factor of 2 of the
true area average concentration on 70
percent of occasions. The correspond-
ing figure for a 24-hour average was
90 percent. These figures indicate the
possibilities of the most elaborate of
existing short-term air-quality models.
Existing long-term models also use
a Gaussian formula with a vertical
diffusion term analogous to iz. The
horizontal diffusion term is replaced
by statistics of wind speed and direc-
tion at each source. There have been
no systematic verifications of the per-
formance of long-term models applied
to multiple sources, but in the original
application to a single source about
75 percent of the computed seasonal
averages were within a factor of 2 of
the corresponding observation.
In the application of both short-
and long-term models based on the
Gaussian formula, two further elabo-
rations are incorporated. The first is
an allowance for decay, transforma-
tion, or deposition of the pollutant,
made by multiplying computed con-
centrations by an exponential decay
factor, characterized by a "half-life."
The second adjustment is for the im-
portation of pollutant from the area
surrounding the modeled area, for
which a detailed source inventory is
not available. The long-term models
include a uniform "background"
term; the short-term models must in-
clude a flux of pollutant across the
boundary. For example, in the Con-
necticut model the New York City-
New Jersey source, which at times can
dominate the air quality over much of
the state, is represented by a uniform
line-source about 30 miles long — a
submodel which quite accurately sim-
ulates observed air quality at the state
boundary.
Deficiencies of Current Models
Experience with the models shows
that, surprisingly, a major source of
difficulty is specification of the mean
wind field in the short-term models
and of wind statistics in the long-term
models. Physically, the difficulty
arises from the large local variability
of measured surface wind, caused by
small-scale topography and phenom-
ena such as sea and lake breezes.
Mathematically, the difficulty is to in-
sure that mass continuity is observed
when adapting three-dimensional phe-
nomena to a two-dimensional frame.
In operating the Connecticut model,
best results were obtained by assum-
ing a simple algebraic form for the
horizontal streamlines (by inspection
of meteorological charts) and modify-
ing them to conform to the large-scale
(i.e., large compared with the grid
size) topography of the state. Specifi-
cation of the diffusion terms, particu-
larly the horizontal diffusion, was
found to be less critical than specifica-
tion of the mean wind.
The decay term has a considerable
effect on the output and in the present
state of knowledge it can only be
specified empirically. For example, in
the Connecticut model, it was found
that the best fit to observation is ob-
tained if a half-life of one to three
hours is imposed on emitted sulfur
dioxide. The chemistry of sulfur di-
oxide in the atmosphere is little un-
derstood. There is no theoretical
support for the adopted value of the
half-life. So far as the source inven-
tory is concerned, the indications were
that deficiencies were not funda-
mental in nature but were due to
omissions in compilation and a natural
reluctance of those emitting pollutants
to disclose the magnitude of their
contribution.
The major theoretical deficiency is
the inability of any model based on
Gaussian-type formulae to handle the
problem of chemically reacting pollu-
tants and the production in situ of
secondary pollutants — circumstances
typical of the production of Los An-
geles-type photochemical smog. This
type of pollution is not likely to be
successfully modeled until concise
computational techniques which can
handle several simultaneous continu-
ity equations have been developed.
This, and improved knowledge of the
chemistry of urban atmospheres, is the
main requisite for further advance.
336
AIRBORNI
Problems in the Ecology of Smog
In spite of increased concern about
the influence of air pollution on man
and his environment, the development
of firm cause-and-effect relationships
has proceeded slowly. Certain con-
spicuous effects, such as reduction of
visibility by pollution particles and
irritation to eyes and respiratory-sys-
tem membranes by the products of
photochemical smog have been well
documented. Other possible conse-
quences, such as chronic illness and
mortality in humans and modification
of the temperature and precipitation
in urban areas, are less well estab-
lished, although in some instances the
evidence is convincing.
Gaps in Scientific Understanding
Reasonably up-to-date reviews of
the effects of smog are available. Re-
views of the effects of individual com-
ponents, such as particulates and
oxides of sulfur, are being issued in
a series of air-quality criteria by the
Environmental Protection Agency
(EPA). In neither instance is atten-
tion focused on the deficiencies of
existing information with a view to
defining what studies are required to
bring the state of knowledge up to
the level required for intelligent plan-
ning. Rather, the EPA publications
attempt to arrive at estimates of ef-
fects from available studies. They
conclude that
it is reasonable and prudent . . .
when promulgating ambient air
quality standards, [that] consider-
ation should be given to require-
ments for margins of safety which
take into account long-term effects
on health, vegetation, and materials
occurring below the above levels.
Such cautions are appropriate in pres-
ent circumstances; but at the same
time a program of systematic investi-
gations should be promoted, to insure
that the margins chosen are really
adequate for safety.
Effects on the Natural Environ-
ment — The effects on human health,
agricultural products, structures, and
other materials have received more
attention than the effects of smog on
the general natural environment and
the weather. It has been shown re-
cently that the pine forests of the San
Gabriel and San Bernardino moun-
tains are dying because of pollutants
from the Los Angeles basin. Vegeta-
tion in the neighborhood of all large
population centers has probably been
similarly affected to some degree. Pol-
lutants may also contribute to the oc-
currence of higher temperatures in
cities than their surroundings, and
pollution from cities and industrial
complexes may produce anomalous
precipitation effects. Definitive inves-
tigations of these relationships are
necessary.
It is also desirable that more studies
be made of the effects of particulate
pollutants and trace gases on the
weather and climate, both locally with
respect to places with high concentra-
tions and globally with respect to the
trend in background concentrations.
Elements of Smog — On a global
scale, it has been demonstrated clearly
that carbon dioxide (COl>) is accumu-
lating in the atmosphere as a result of
combustion of fossil fuels, and the
amount of temperature rise to be ex-
pected due to modification of the radi-
ation balance has been estimated by
theoretical computations. There has
been some evidence adduced, less
conclusive but nevertheless quite
plausible, that concentrations of par-
ticulates from pollution are likewise
increasing on a worldwide basis. It
has been suggested that the increase
of particulate pollution tends to pro-
duce a cooling which offsets or out-
weighs the warming effect of CO2.
Information is lacking on whether
or not concentrations of other gase-
ous contaminants, such as carbon
monoxide, sulfur dioxide, and oxides
of nitrogen, are similarly rising
throughout the world. They probably
are, since the removal processes for
some contaminants, such as carbon
monoxide, are much slower and less
efficient than those for CO-. A gen-
eral worldwide upward trend in these
toxic substances would be of urgent
concern. A rise in these background
values means that the additional pol-
lution emitted in urban and industrial
areas would produce even higher local
concentrations. Ultimately, such in-
creases would lead to levels that ex-
ceed thresholds for deleterious effects
even at large distances from such
areas.
It is thus important to establish a
network of monitoring stations to
measure particulate and gaseous con-
taminants at representative locations
throughout the world, both in and
near pollution sources, where almost
all present measurements are made,
and in remote locations where the
background values will be obtained.
Furthermore, it is important to meas-
ure many contaminants, not just par-
ticulates and sulfur dioxide, as is the
case at most present-day monitoring
stations.
Thermal and Water-Vapor Pollu-
tion— A further consideration is
thermal pollution and water-vapor
pollution. The effects of introducing
large amounts of heat into the atmos-
phere at industrial plants, particularly
electric generating plants and in urban
areas, are poorly understood. When
cooling towers are used, and also in
the combustion of hydrocarbons,
larger amounts of water are intro-
duced than would evaporate or tran-
spire naturally. This addition of water
vapor may have noticeable influence
on the radiation balance (temperature
effects) and on the occurrence of fog,
cloud, and precipitation. Definitive
studies of these effects are needed.
337
PART X — ENVIRONMENTAL CONTAMINANTS
Alternative Courses of Action
All of the above considerations are
aspects of the general impact of tech-
nology on the environment. The con-
cept that technological development
constitutes "progress" must be modi-
fied so that all effects of the develop-
ment are weighed, not just the profits
to industry and the immediate benefit
to the consumer. All the social costs,
including the far-reaching conse-
quences to the health of the commu-
nity, the aesthetic properties of the
environment (e.g., visibility), and the
soiling of clothes and buildings,
among others, must be figured in the
benefit/cost ratios that are used to
evaluate the desirability of a tech-
nological change.
The problems of conservation of
natural resources and of waste dis-
posal enter in an interacting fashion.
Nonretrievable consumption of re-
sources must be replaced as much as
possible by recycling, in which wastes
are retrieved and re-used rather than
thrown away in the air, water, or soil
where they constitute a pollution
problem. The whole production-con-
sumption organization of society
needs careful study, to develop proc-
esses that truly maximize social bene-
fits and minimize harmful conse-
quences. The corollary is that social,
political, and economic organization
of society will likewise require revi-
sion, for under the present pseudo-
laissez-faire situation long-range ef-
fects will not be given priority over
immediate profits in determining the
course of action.
Much of the impact of man on the
environment has arisen because, as a
result of technological advances, the
human population has increased ex-
ponentially. This increase cannot go
on. Even with exploitation and even-
tual degradation of every part of the
earth, a point must be reached when
food, air, and water are inadequate to
support one additional person at the
lowest level of subsistence compatible
with life. Figure X-5 illustrates some
of relevant variables. We can hope
that this stage will never be reached.
We should strive for a stabilization
of the population at a level at which
the quality of life, as sustained by the
quality of the environment, is not
merely tolerable but truly enjoyable.
It has been suggested that man will
adapt to a polluted environment, just
as organisms in general adapt to sur-
rounding conditions by evolutionary
processes. However, the changes pro-
duced by technology have been too
rapid for evolutionary processes to
cope with. Long before mutations
produce humans whose blood rejects
carbon monoxide — rather than hav-
ing it combine to form carboxyhemo-
globin, which limits the transport of
oxygen by the blood — the accumu-
lation of carbon monoxide and other
toxic substances in the atmosphere
may make man extinct.
One alternative is technological
adaptation: development of appropri-
ate gas masks, air-conditioned homes
and vehicles, or even enclosures of
entire cities in which the air is proc-
essed to remove toxic substances
and protect man from the poisons he
puts into the surroundings. But surely
it is more sensible to use technology
to avoid putting the contaminants into
the atmosphere than to apply it to
processing the air to remove them be-
fore we breathe it.
Figure X-5 — PROJECTION OF PHYSICAL, ECONOMIC,
AND SOCIAL RELATIONSHIPS
POPULATION
2100
The graph shows five physical quantities"plotted on different vertical scales, but
combined in the same graph to emphasize their relationship. The variables and
their units, projected to the year 2100, are: population (total number); industrial
output per capita (dollar equivalent per person per year); food per capita (kilogram-
grain equivalent per person per year); pollution (multiple of the 1970 level);
nonrenewable resources (fraction of 1900 reserves remaining). Although the model
is at best only a first approximation containing many assumptions and gaps of
knowledge and data, it does suggest some of the factors that could combine to
limit world growth.
338
2. AIRBORNE BIOLOGICAL MATERIALS
Atmospheric Dispersal of Biologically Significant Materials
An Aerobiology Program has been
established within the International
Biological Program (IBP). The United
States Aerobiology Program under the
IBP has been in operation about two
years. It is the strongest national
aerobiology program, with the Neth-
erlands nearly as active. International
collaboration is growing steadily.
The activities of the Aerobiology
Program are generating new ap-
proaches to studies of biologically sig-
nificant materials in the atmosphere,
such as spores, pollen, fragments of
algae and molds, minute insects, and
toxic particles and gases. Until now
studies of these materials in the at-
mosphere have been done in highly
individualistic ways, with almost no
comparison of work by different au-
thors and no theoretical bases for
guiding research and organizing the
resulting information. There are a
few notable exceptions, such as the
well-conceived bodies of research in
the 1930's and 1940's by Stakman and
Harrar on cereal-rust epidemiology on
the North American plains. But now
there are new pressures to guard food
crops against losses, to reduce human
disease, to curtail additions to atmos-
pheric turbidity, to clean air of nox-
ious pollutants, and many other tasks
involving atmospheric dispersal in
ecological systems, all of which are
objectives to which aerobiologists can
contribute. (See Figure X-6)
The science of meteorology has be-
come "systems ordered," from the
research-planning to the data-han-
dling phases, and is fast becoming
coordinated on a worldwide scale with
respect to observations. Now is a
propitious time for aerobiologists to
link up with meteorologists for the
mutual benefit of their researches and
Figure X-6 — ATMOSPHERIC PARTICULATE MATTER
IMPORTANT IN AEROBIOLOGY
Diameters
(meters)
10 >
10 '
Commonly
Used Units 001u 01u
(microns, millimeters & centimeters)
10-
,lu
Fall Speeds
(cm/sec)
_Browman
movement
1(H
lu
.003
io-5
lOu
10-" 10-3 io-?
lOOu 1 mm 1 cm
30
.300
ation
Permanent Suspension
-• — (Gravitational
fallout is not
significant)
■ Smokes -
Transition_
Region
Dusts
(fine)
Transient Particulates
(only strong winds can
sustain these in the
atmosphere)
Dusts
(coarse)
Haze particles
■ Condensation nuclei
Viruses *-
-» Bacteria
Algae
-— Protozoa
Fungus
"*" spores "
Lichen fragments
Moss
spores"
Pollen
Fragments of plants,
seeds, insects, &
other microfauna
The table gives some physical properties of particulates encountered in aerobiology
— diameter, expressed in meters and other commonly used units, and approximate
terminal fall speed. From an aerobiological point of view, smokes, fine dusts, haze
particles, condensation nuclei, viruses, bacteria, and algae are the atmospheric
particulates of greatest concern. This is because gravity does not cause them to
fall out of the atmosphere as do most of the heavier particulates in the lower-right-
hand part of the table. Instead, they are deposited on surfaces by impaction or
are washed out by precipitation.
339
PART X — ENVIRONMENTAL CONTAMINANTS
for aerobiology to derive out of that
association help in developing a theo-
retical framework based on ecological
systems approaches.
A planet-wide network for moni-
toring ecological systems is clearly
essential to the human welfare. We
need both warning systems that will
permit measures for reducing or
avoiding injury to ecological systems,
and prediction capabilities wherein
the potential for injury is shunted
aside or eliminated before risk of in-
jury arises. These will inexorably re-
quire baseline data against which to
measure change, which suggests that
we should establish monitoring sta-
tions immediately.
One of the most feasible systems to
begin with is one for monitoring ma-
terials in the atmosphere. Much of
the technology for sampling gases and
particles in the atmosphere is at a
stage of acceptable reliability, and
basic stations and networks already
exist for observing and measuring
fundamental physical parameters. Ex-
tensive and costly efforts are already
applied to counteract the diseases of
plants and animals by airborne agents,
human allergies resulting from air-
borne materials, and insect pests car-
ried on winds.
The necessary data base is less well
ordered, however. There is an abund-
ance of information about spores of
common plant-disease fungi (smuts,
rusts, and the like), and there is a
considerable literature on atmospheric
pollen sampled by allergists and paly-
nologists. But only scattered studies
of other particles of biological origin
have been done, and the information
on biological particles in general is in
an almost completely unordered state.
Some good survey data exist on radio-
nuclide particle fallout, but only scat-
tered data of widely different relia-
bilities concerning other inorganic
particulates. Local observations on
certain polluting gases have been
faithfully recorded for ten years or
more in some cities, but the informa-
tion is mostly uncorrelated with ob-
serving stations in other cities or with
other phenomena. In short, virtually
all of the data on dispersal of biologi-
cally significant materials in the at-
mosphere is unordered, and there is
no data system prepared to receive,
let alone store and retrieve it.
By contrast, meteorological data are
well ordered and handled in the
framework of systems analysis guided
by adaptable theory. Furthermore, as
consequences of the several Interna-
tional Geophysical Years and agencies
such as the World Meteorological Or-
ganization, meteorology is organized
on a worldwide basis. The aerobiolo-
gists can profitably take some cues
from the meteorologists.
There follow comments on six ma-
jor problem areas of aerobiology —
the systems approach, plant and ani-
mal diseases, airborne allergens, ur-
ban and indoor environments, insects
and other microfauna, and phytoge-
ography and genecology of "aerial
plankton." A concluding section
treats the current efforts in aerobi-
ology and prospects for the future of
the science.
Systems Approach to Aerobiology
There is abundant information on
movements of biological materials
through the atmosphere. Nearly all
attention to this topic has been ad hoc
and empirical, however. The time has
come when the aerobiologist, the me-
teorologist, and the applied biologist
(e.g., agronomist, forester) or engineer
(e.g., sanitation officer, industrial de-
signer) should work together system-
atically on problems of predicting the
time, place, and probability of deposi-
tion of given material from the atmos-
phere. The objective should be to
develop functional models of the mul-
tiple-parameter problem of the entire
process — particle formation, release,
takeoff, aerial trajectory, scavenging
or deposition, germination (if viable),
and effect on biota or environment —
so that prediction is based on all ob-
servable parameters, with standard-
ized criteria for observations and
measurements. (See Figure X-7)
Development of such models will
provide schemes for ordering existing
information and storing new informa-
tion in a re-usable and retrievable
form. If the models are to have con-
tinued and improving usefulness, they
must also be suited to feedback cor-
rections so that new information and
new solutions improve the validity of
the models.
Research Needs — This is a diffi-
cult set of theoretical and technical
problems from the standpoint of both
biology and meteorology. Continued
and intensified study of the biology of
spore formation and release, ques-
tions of survival of living material
under different atmospheric condi-
tions, problems of host specificity and
conditions favoring epidemics, and
similar matters are needed. From the
meteorological standpoint there is
need for development of joint prob-
ability meteorological statistics con-
nected with the favorable conditions
for spore release, quantitative trans-
port, and the optimum infection
"climate."
Recent advances in measurements
of the planetary boundary layer and,
in particular, the wind, temperature,
and humidity profiles in the near sur-
face layer promise to permit estimates
of the critical parameters both from
direct measurements and inferences
from large-scale meteorology. Espe-
cially promising is the development
of numerical prediction models from
which three-dimensional trajectories
of material can be calculated; the
direction and speed of transport of
the material can be forecast 72 to 96
hours in advance with steadily im-
proving accuracy.
In the absence of current studies to
evaluate the frequency of favorable
conditions and the subsequent occur-
rences or non-occurrences of infec-
tions, the ability of a total biological-
meteorological-agricultural warning
system to provide usable and depend-
able predictions remains to be deter-
mined. Contributions toward solving
these general problems are increasing.
340
AIRBORNE BIOLOGICAL MATERIALS
Aerobiology of Plant and
Animal Diseases
Figure X-7 — COMPONENTS OF A MODEL FOR POLLEN AEROBIOLOGY
Geographic Plant
Distribution
Antecedent Sun
and Rainfall
"^
Catastrophic
Events
PRODUCTION
Pollen
Maturation
EMISSION
Day
Length
REFLOTATION
DISPERSAL
Settling
Rates
Wind Structure
DEPOSITION
Temperature
Structure
Retention by
Substrate
Age Distribution
in Stand
Genetic Pollen Production
Potential
Morphology of Flower
for Emission
Rainfall
Sunshine
Relative Humidity
Atmospheric Turbulence
Pollen Morphology,
"Flight Characteristics"
Shapes of Plants
Vertical and Horizontal
Patterns
Physiography
h
Microclimate, Wind Speed
Temperature, Structure,
Turbulence
Rainout
Atmospheric Factors
Any scheme for modeling, and hence prediction, of pollen concentration must
include the many factors shown in the diagram, in approximately that relationship.
There are unanswered questions at many points in this conceptualized model, so
that accurate predictions of pollen concentration at any point in space and time
will not really be available with any degree of accuracy in the near future.
Plant Diseases — The
supply of the world depends or
crops, every one of which is subject to
diseases or pest attacks that can and
do prejudice entire crops over regions
of considerable size. (See, for exam-
ple, Figure X-8) For cereal-grain
crops, the answer to rust and smut
diseases has been to continue to breed
resistant strains, each of which has a
useful life of one or two decades, until
the parasitic organism develops a
form that overcomes the resistance of
the host. Can this go on indefinitely,
especially since populations of wild
ancestors of these horticultural species
are disappearing?
For some fungus diseases of crop
plants, prevention is exercised by re-
stricting culture to certain climates or
special soils. In other instances chem-
ical inhibitors of fungus growth are
administered. Similar measures are
used against insect pests and sucking
insect vectors of virus diseases. The
inocula for these diseases and pest
attacks are in most instances carried
passively by the atmosphere. But only
in a few instances do we know in
what quantities, in what directions,
and with what survival as viable en-
tities the inocula are transported and
deposited. The "triangle of epidemiol-
ogy"— origin, transport or vectoring,
and infection — thus depends heavily
on information about atmospheric
transport. We could learn much about
probabilities for transport of many
kinds of organisms through full
knowledge of the transport of a few
that we can readily collect in transit,
identify with certainty, and test re-
liably for viability.
It has been found appropriate for
aerobiology, at least in the context of
the IBP, to take under its wing certain
studies of diseases that are not con-
fined to atmospheric transport consid-
erations. From an ecological view-
point, diseases of crop plants are
exaggerations of natural situations be-
cause of ecological imbalances intro-
duced by agricultural practices such
341
PART X — ENVIRONMENTAL CONTAMINANTS
Figure X-8 -
AVERAGE ANNUAL LOSSES FROM CROP DISEASES
IN THE UNITED STATES
Commodity Group
Loss from potential production
%
Value
Reduction
(in '000 dollars)
Field crops
13%
$1,890,836
Forage crops and pasture ranges
11
808,701
Fruit and nut crops
16
223,505
Ornamental plants and shade trees
12
14,099
Forage seed crops
14
23,584
Vegetable crops
13
2,990,839
Total
13
3,251,114
The figures in this table represent potential production in the U.S. from 1951 to
1960, inclusive — i.e., the production that would have been realized had plant
diseases not been present. Most of the losses are due to rusts, smuts, viruses,
fungi, and molds that are viable biological material transported in the atmosphere
by the wind.
as extensive acreages of monocultures,
wide use of genotypically identical
populations, unusual growth of foli-
age or fruit through use of chemical
fertilizers and irrigation, and elimina-
tion of associated and competing
species. Some aerobiologists see op-
portunities to study the cultural checks
and balances of plant diseases at the
centers of origin of the crop species,
and also opportunities to learn about
pathogenic germ-plasm variability,
survival, and migration. Out of such
studies of "origins and sources" of
plant diseases the United States Aero-
biology Program is endeavoring to de-
rive new biological information that
will constitute improved input for
the epidemiological models described
above.
Human and Animal Diseases — Al-
though various human and animal
diseases are spread by transmission of
bacteria, spores, or viruses in the air,
most of the atmospheric transport is
probably over a short distance and
within a water droplet or on some
other particle. Studies of these par-
ticles have been confined to indoor air,
especially of hospitals. However, a
number of pulmonary mycotic dis-
eases are acquired by the inhalation
of spore-laden dust or other organic
particles in the free air indoors or
outdoors. Histoplasmosis, coccidioi-
domycosis, North American blasto-
mycosis, cryptococcosis, and nocari-
dosis may result from exposure
of humans or animals to such infec-
tious materials. The fungi or fugus-
like microorganisms causing these
diseases are unique in that they are
free-living in nature but also find the
susceptible mammalian body a suit-
able growth environment. In a small
percentage of cases, the infectious
agent disseminates from the pulmo-
nary tract involving a multiplicity of
organs and tissues.
From knowledge accumulated to
date it appears that some of these
etiologic agents exist in certain foci
in nature and are often associated
with avian or chiropteran species.
Some of these agents also exist
in sharply demarcated geographical
areas, such as a portion of a (Milan,
Michigan) schoolyard which was a
source of histoplasma infection. In-
fectious particles become airborne due
to winds or mechanical disturbance
of soil in which the fungi are present.
Most of the work on control has been
directed toward eradicating the infec-
tious agent by chemical sterilization
of its natural habitat. Some studies
have been made on the ecology of
these fungi, but much more work re-
mains to be done.
Airborne Allergens
Allergenic pollen and spores in the
atmosphere have been under study
for nearly fifty years as clinical prob-
lems, with varying degrees of atten-
tion to botanical sources and phenol-
ogy of the airborne particles. Greater
uniformity in air sampling and report-
ing techniques, and better organiza-
tion and availability of accumulated
information on the distribution of
allergenic particles, are clearly neces-
sary for improved prediction of ex-
posure. Improvements of these kinds
are in progress nationally and inter-
nationally, fostered by appropriate
organizations including the IBP Aero-
biology Program.
Research Needs — Especially in
connection with urban areas with high
levels of gaseous pollutants in the at-
mosphere, there is need for investiga-
tion of possible interactions between
biological (spores, pollen, fragments
of fungus mycelium, and similar ma-
terials) and nonbiological (gases such
as sulfur dioxide, hydrogen fluoride,
and so on) emissions in transit. Fur-
thermore, the extent to which these
two groups of agents may induce
synergistic effects on plants and ani-
mals is a subject that merits further
attention. Regarding atopic allergy,
there is strong suggestive evidence
that augmented respiratory changes
due to simple gaseous irritants may
be expected in persons with preexist-
ing inflammatory changes due to ex-
posure to inhalant or ingestant aller-
gens. The concept is growing that
specific segments of the general popu-
lation may be predisposed to experi-
ence adverse effects from air pollu-
tants; it would be valuable to explore
342
AIRBORNE BIOLOGICAL MATERIALS
the possibility that aeroallergens may
exert such a selective influence.
An additional aspect of aerobio-
logical health effects that seems to
warrant study relates to possible
(nonspecific) irritant effects of bio-
logical particulates due to vasoactive
materials carried by them. Cultures
of certain hyphomycetes (molds that
produce conidia on loose, cottony
hyphae) do synthesize such agents,
and it would be useful to know
whether airborne spores could do so
in the concentrations encountered in
nature. Many "allergic" persons re-
port "irritation," hoarseness, and mu-
cous membrane burning following
massive exposure to fragments of
fungi (e.g., while raking leaves), sug-
gesting the possible action of chemical
irritants. Possible direct interactions
of eluted materials with the human
respiratory flora might also be ques-
tioned, since purulent bacterial infec-
tion often follows rapidly on such
exposures.
Present Urgency — The recognition
that precipitating antibody-mediated
reactions to biological agents can pro-
duce systematic effects and granulo-
matous lung disease (i.e., farmer's
lung, bagassosis, maple-bark disease)
provides new incentives for exploring
and characterizing the breadth of bi-
ological materials in free air. The
dearth of even preliminary informa-
tion regarding incidence and variety
of bacteria in free air (apart from hos-
pital wards and operating rooms) is
distressing. Similarly, background
knowledge and general techniques are
at hand for making studies of algal,
actinomycete, and protozoan bodies
in the "aerial plankton," but scarcely
a beginning has been made. Study of
algal, insect, and acarid material in
air will require development of meth-
ods for identifying these components
either as individual particulates or as
components of bulk samples.
Aerobiology of Urban and
Indoor Environments
Assemblages of species and mate-
rials in the atmosphere of the urban
environment are markedly different
from rural and wild landscape as-
semblages.
Outdoor Environment — One com-
ponent in urban air has been derived
from the local region or from even
wider areas, depending on the char-
acteristics of the particles for remain-
ing airborne. Atmospheric concen-
trations of rust and smut spores from
agricultural lands come into urban
areas in only slightly reduced num-
bers. In addition, the urban pollen
spectrum is dominated by street and
park trees (elm, oak, ash, pine, birch,
mulberry) and weeds of alleys and
vacant lots (grasses, lambs-quarters
and pigweeds, and the ragweed
group). There are greatly increased
local concentrations of mold spores
(conidiospores, conidia, etc.), frag-
ments of algal colonies, and "organic
trash" that tends to accumulate in
nooks and crannies in masonry and
asphalt where normal processes of
humification and recycling are ineffec-
tive in disposing of it. Soil surfaces,
even in the heart of a city, are prob-
ably helpful in taking some of these
offensive dust components out of the
air and converting them into an in-
nocuous humus component of the soil.
However, there are only limited soil
surfaces in the hearts of cities.
Indoor Environments — Inside
dwellings and industrial buildings
there are entirely unique and ex-
tremely varied assemblages of air-
borne materials, as one would expect.
Old wooden buildings accumulate
wood-rotting fungi, molds, and in-
sect and mite populations that make
up "house dust," to which certain
persons are very sensitive. It was
recently reported that North Ameri-
can and European house-dust mites
(Dermatophagoides spp.) were found
in dusts used for commercial extracts
in treatment of allergies. Masonry
buildings, especially in damp climates,
develop mold fungus and algal col-
onies that populate moving air with
spores and fragments. In these struc-
tures, parts of dead spiders, mites,
insects, and other organic matter
become mixed with fungus n
to form various substrates for bac-
terial decay or, in larger masses, site
for insect, mite, or milliped colonies.
Very little specific attention has
been given to the airborne plant and
animal material of indoor environ-
ments. Questions arise with regard
to saprophytic, or at least non-
invasive, organisms, since reactions
to these involving skin sensitizing
and precipitating antibodies or de-
layed (cell-mediated) hypersensitivity
may be involved etiologically in dis-
eases presently of unknown origin.
Evidence from sampling strongly sug-
gests that domestic humidifiers pose
a real hazard for fungus-sensitive
patients; careful investigations of in-
door allergens is warranted. Forced
ventilation through ducts that are not
periodically cleaned is a potential
source of continuous dispersal of
spores, mycelia, and dust. The longer
the occupancy, the greater the accu-
mulation of offending materials. Al-
lergists in the United States and
Europe are increasingly interested in
these aspects of indoor environments.
Recent reports of a small epidemic
of severe lung disease due to thermo-
philic antinomycetes (probably Mi-
cromonospora sp.) contaminating a
commercial air-conditioning system
underscore the potential value of
work in this area.
Atmospheric Dispersal of Insects
and Other Microfauna
Transport of insects and other very
small animals by wind is proving
worthy of special study, not alone
for the biogeographical implications
but because of the inherent potential-
ity of pest epidemics and vectoring of
diseases. In regions where alfalfa
and mixed hay crops are grown, sum-
mer winds and disturbance by mow-
ing usually launch great numbers of
leaf hoppers, spittle bugs, and other
small sucking insects into the air.
Once airborne, these insects are car-
ried as much as 100 miles downwind,
where they settle down on new crops,
343
PART X — ENVIRONMENTAL CONTAMINANTS
in some instances transmitting plant
viruses they brought with them. The
U.S. Department of Agriculture has
worked out many of the disease-
transmission possibilities, but we do
not yet have enough coordinated ob-
servations to be able to assess the
significance of such insect transport.
In the tropics, vectors such as the
tsetse fly generally show patterns of
narrower endemism, and this should
be studied against the possibility of
human activity inadvertently creating
favorable conditions for a dangerous
vector in a new area. There is clearly
need for assessment of existing
knowledge in this area and an effort
to determine efficient courses for
further action.
"Aerial Plankton" in Relation to
Genecology and Phytogeography
A neglected but obvious functional
aspect of the aerial transport of pol-
len and spores, and of all other par-
ticles that are propagules, is that this
process represents transfer of genetic
material from one geographic area to
another and, in the event of germi-
nation on the new site, injection of
more or less different genetic material
into a population. If we are to under-
stand the ecological genetics, or "gen-
ecology," of populations, quantitative
as well as qualitative aspects of at-
mospheric dispersal of viable prop-
agules and pollen must be studied.
Applications having considerable eco-
nomic importance will follow closely
in such activities as breeding of hy-
brid crop plants and forest trees.
In the course of observing aerial
transport of viable propagules, we
should be on the lookout for those
that would have come from a distant
source. This evidence would help to
resolve many old arguments for or
against long-distance transport as ex-
planations of wide disjunctions of
range.
Wind transport of humus and
other organic material out of one eco-
system unit and into another has
become a matter of concern to ecol-
ogists studying productivity in detail.
They find this export and import of
materials and energy attaining sig-
nificance in the production budgets
of climates that are dry and windy,
at least for seasonal periods. Aero-
biologists are currently trying to help
the ecologists of the IBP Grassland
Biome Project in Colorado to obtain
reliable measurements of amounts of
material in transit at given times and
accumulating on different sites over
specific time intervals.
Historical Studies — "Microfossil"
pollen grains, spores, diatoms, and
other small and identifiable organic
particles in sediment have been used
for over half a century to obtain
stratigraphic correlations and paleo-
ecological reconstructions. The most
detailed and refined uses are made
of late Quaternary microfossils be-
cause they are so nearly like the
living forms of which we have first-
hand knowledge. Several aerobiolo-
gists are endeavoring to identify
strategically located sedimentation
sites and airborne biological forms
accumulating in them today in order
that the older sediments might, in
effect, extend the baseline for envi-
ronmental monitoring back in time
some hundreds or thousands of years.
Opportunities may present them-
selves for linking in time the changes
indicated by airborne particles with
changes indicated by aquatic-system
elements. Some inland lakes are
known to have sediments that are
annually banded, so that precise dates
can be obtained for the record of the
past. One such lake in Minnesota
has nearly 10,000 annual bands in
its sediments.
Prospects for Aerobiology
In his book Microbiology of the
Atmosphere, Gregory stated:
Our knowledge of the terrestrial
air-spora is fragmentary in the
extreme. The air has never been
systematically explored simultane-
ously in different parts of the
world by comparable methods.
There is a heap of accumulated
data. . . . Here and there are in-
triguing suggestions of phenomena;
but many of the data are unin-
terpretable, and we need a fresh
study of aerobiology as part of a
vast terrestrial process.
The IBP Aerobiology Program is ini-
tiating just such efforts as a transient,
first step. It has sponsored, jointly
with the Environmental Protection
Agency, a conference entitled "Aero-
biology Objectives in Atmospheric
Monitoring," at which meteorologists
and aerobiologists drew up the first
lists of priorities for information ac-
quisition and assessed the practicali-
ties of sampling and data processing.
These people will look ahead to inte-
grating these activities into the pro-
posed GNEM (Global Network for
Environmental Monitoring). The
prospects are that support for world-
wide environmental monitoring, in
aerobiology at least, will be well re-
paid by the benefits realized.
The Secretary-General of the
United Nations is calling for an inter-
national body that will supervise
sentinel and warning stations for
detrimental changes in environments
and biota all over the earth, and the
plans for the GNEM constitute the
preliminary blueprint. ICSU (Inter-
national Council of Scientific Unions)
and its member organizations — IUBS
(International Union of Biological
Sciences), in particular — are ready-
ing a larger scheme, called the "Man
and the Biosphere" program, designed
to interpret the changing conditions
for man and the organisms sharing
the earth and supporting him, and to
plan for improvement of conditions
for human life in the future.
For at least the decade of the
1970's, organizations serving aerobio-
logical needs must be kept adaptable
and responsive to widely different
344
AIRBORNE BIOLOGICAL MATERIALS
opportunities. This argues for a
small, volunteer steering group, rep-
resenting diverse interests in aero-
biology and dedicated to international
cooperation. This steering group
should have membership from gov-
ernment, academic institutions, and
appropriate industrial organizations.
A large, monolithic research organi-
zation does not seem appropriate, but
provisions must be made for receiv-
ing, processing, storing, and i
information, hopefully by a mode;
addition to some established data
center.
Biological Monitoring Techniques for Measuring Aero-allergens
Diseases caused by inhalation of
airborne biological particles have long
been recognized as important public
health problems. These diseases,
commonly termed hay fever or polli-
nosis, are estimated to affect about
10 percent of the U.S. population (a
much greater percentage than are
known to be medically affected by all
man-made air pollutants) and some-
times develop into more serious dis-
eases such as bronchial asthma. In
addition to causing considerable dis-
comfort to affected individuals, these
diseases cause a substantial economic
loss in terms of time lost from work
or school, lowered efficiency, and di-
rect medical costs. These diseases are
most frequently caused by pollens
from anemophilous plants and by a
few groups of fungus spores, but
other known or potentially allergenic
airborne biological particles include
spores from ferns and mosses, algae,
plant hairs, and insect scales. Aero-
allergens vary greatly in size, shape,
density, and other physical character-
istics, but many are more or less
spherical and most have dimensions
between 1 and 100 microns.
Aeroallergens are commonly sam-
pled from the atmosphere to deter-
mine their presence or absence,
relative abundance, spatial distribu-
tion, and both seasonal and diurnal
patterns of occurrence. Past studies
have given considerable qualitative
information for a few common par-
ticles such as ragweed pollen, but few
data have been obtained for many
known or potential aeroallergens.
Until recent years, sampling devices
capable of giving a quantitative meas-
ure of concentration for particles in
this size class did not exist and even
today are little used. However, ac-
curate concentration measurements
are necessary for such important
studies as the following:
1. Determination of the spatial
and temporal changes in dis-
tribution of each important aer-
oallergen and the relationships
of such changes to meteoro-
logical and other factors.
2. Studies of the relationships be-
tween aeroallergen concentra-
tions and the onset or severity
of allergic symptoms in suscep-
tible patients.
3. Evaluating the success of medi-
cal treatments.
4. Planning and evaluating the
results of weed control or eradi-
cation programs.
5. Documenting changes in aero-
allergen concentrations caused
by changing land-use patterns
and urbanization.
6. Determining the seasonal and
diurnal emission patterns from
sources of aeroallergens and
relating these patterns to other
variables.
7. Determining the efficiency of
particle-removal mechanisms
such as washout by precipita-
tion and impaction by vegeta-
tion.
8. Determining possible syner-
gistic effects between aeroaller-
gens and other air pollutants.
Despite the obvious need for more
study of aeroallergens, such research
has been hindered by the difficulty of
obtaining accurate and representative
samples of these airborne particles
and by the tedious methods that
must be employed to identify and
count the samples collected.
Evaluation of Current
Scientific Knowledge
Nearly all research on aeroaller-
gens and their relationship to man
depends on sampling devices and
techniques, but the accuracy of such
sampling devices is critically depend-
ent on the characteristics of the par-
ticles they are employed to sample.
Data Base — Information on the
characteristics of aeroallergens is far
from complete. Although the size
and shape of airborne pollens are
generally known, little useful infor-
mation exists on their density. The
size and density of some pollens are
known to change with age or with
changes in humidity, but few meas-
urements are available. For example,
it is not known whether the bladders
on conifer pollens are inflated or de-
flated while airborne or whether this
varies with conditions. Information
on fungus spores is more sparse; no
density determinations seem to have
been made, and many spores sampled
from the atmosphere cannot be iden-
tified as to source species. Even less
information is available on other ac-
tual and potential aeroallergens.
The sources of airborne pollens are
generally known as to geographic re-
gion and habitat (see Figure X-9),
345
PART X — ENVIRONMENTAL CONTAMINANTS
Figure X-9 — DISTRIBUTION OF RAGWEED POLLEN IN THE UNITED STATES
Ragweed pollen is responsible for more than 90 percent of all the pollinosis in the
United States. Some 50 species of ragweed are known; they are found in all fifty
of the United States, but the highest concentrations are in the North Central and
Northeastern states. They grow alongside highways, in plowed fields, and in other
disturbed areas. Since there is more and more disturbed soil each year, there
is more and more ragweed, and, hence, there are more and more pollen and hay-
fever sufferers.
but the location of local sources that
affect specific receptors is often not
known. Seasonal patterns of occur-
rence are fairly well documented for
most important species, but diurnal
patterns have been studied for only a
few, and the relationships between
these patterns and other variables are
little known. Sources of fungus
spores are less well known than
sources of pollen, and diurnal and
seasonal spore concentration patterns
have seldom been studied.
Although the dispersion mecha-
nism plus the source strength will
determine the concentrations that are
sampled at any given point of inter-
est, quantitative studies of pollen
transport and dispersion from known
sources have been made by only two
research groups in this country.
These studies have indicated that
pollens are dispersed much like inert
particles of similar size, and that
meteorological diffusion theory may
be applied if particle characteristics,
source configuration, and output rate
are known.
Concentrations of aeroallergens at
sampling locations may vary by at
least several orders of magnitude.
Close to a local source, such as a
field of ragweed, concentrations can
average over 75,000 grains per cubic
meter during a several-hour period.
Short-period peak concentrations
probably exceed this value by several
times. At locations distant from
346
AIRBORNE BIOLO' KIALS
sources, ragweed pollen concentra-
tions seldom exceed 200 grains per
cubic meter during the emission sea-
son. Other aeroallergens also vary
greatly in concentration, and certain
fungus spores are often present in
great numbers. These variations in
concentration lead to difficulties in
choice of sampling methods and pe-
riods. An efficient sampler may over-
load in the presence of high concen-
trations, while an inefficient one may
not take an adequate sample if con-
centrations are low.
The Limitations of Sampling Meth-
ods — Obtaining a sample of air-
borne particles in the aeroallergen size
range may be accomplished by many
samplers, but obtaining an accurate
or representative sample over all size
ranges commonly present is a difficult
problem not solved by any sampler
in current use. In fact, it can be
stated categorically that no single
sampling method so far devised is
capable of obtaining a representative
sample of all aeroallergens from the
free atmosphere and that no perfect
sampling method exists for any.
The principal cause of difficulty in
sampling particles in this size class is
the momentum that they acquire in
moving air as a result of their mass
and velocity. This inertia causes their
path to deviate from that of the sur-
rounding air if that air is forced to
change speed or direction, as by a
sampling device.
With the exception of isokinetic
sampling, which has not yet been
perfected for use in the free atmos-
phere, sampling methods in which air
and, hopefully, its entrained particles
are drawn into an entrance or orifice
tend to be inefficient for large parti-
cles since these often fail to follow
the airstream into the entrance. Since
momentum increases with particle
size, particle density, and air speed,
it follows that such samplers are
not only size-selective but vary in
entrance efficiency with wind speed.
In general, methods of removing
from the airstream those particles
that do get into the entrance are satis-
factory. These methods include fil-
tration, impaction, liquid impinge-
ment, and electrostatic attraction.
Suction-type samplers are sometimes
used for sampling aeroallergens, but
cannot be recommended except for
the smaller fungus spores.
The most common device for sam-
pling aeroallergens is a microscope
slide coated with adhesive and ex-
posed horizontally, usually between
rain shields. This "gravity-slide," or
"Durham" sampler, collects by tur-
bulent impingement and gravitational
settling, but is generally unsatisfac-
tory since the volume of air sampled
cannot be defined and the catch is a
function of wind speed, turbulence,
and wind direction relative to the
long axis of the slide as well as the
concentration of particles and their
characteristics. Although still in wide-
spread use and of some value for
qualitative purposes, it should be re-
placed by other samplers where quan-
titative measurements are desired.
To date, the most satisfactory de-
vices for sampling aeroallergens are
those which collect by impaction.
Here, the momentum of the particle
is used to effect its capture; efficiency
increases as particle size, particle den-
sity, and wind speed increase. How-
ever, efficiency of wind impactors
does vary with particle parameters,
so that each particle of interest is
likely to be sampled with a different
efficiency and the efficiency for all
will vary with wind speed. In gen-
eral, samplers of this nature must
be accompanied by a sensitive ane-
mometer, and the catch corrected for
sampling efficiency. An advantage of
wind-impaction methods is that im-
paction efficiency can be computed
mathematically for certain simple
geometric shapes like cylinders and
spheres if impactor dimensions, par-
ticle parameters, and wind speed are
known. For a given collector and a
single particle type, impaction ef-
ficiency can be calculated and graphed
as a function of wind speed. (See Fig-
ure X-10) Total collection efficiency,
however, depends on both
and retention efficiency and ad<
adhesive must be used on collecting
surfaces to insure good retention of
impacted particles. Wind-impaction
samplers are usually cylindrical in
shape and are commonly mounted on
a wind vane so that the sample is
taken only on one side. Such sam-
plers have normally been used only in
controlled research programs and are
not recommended for general use.
The disadvantages of wind-impac-
tion samplers were largely overcome
and their advantages retained by the
development of powered impaction
devices such as the rotorod, rotobar,
and rotoslide samplers. In these, the
sampling surfaces are rotated through
the air at a high rate of speed, giving
virtually constant impaction efficiency
for any given particle type. Al-
though efficiency may still vary with
particle size and density, it is gen-
erally much higher than for wind-
impaction samplers. Adequate reten-
tion requires a thicker or better ad-
hesive, since particles impacting at a
high rate of speed tend to bounce
off. Since the efficiency of these
devices is high and their sampling
surfaces small, overloading becomes
a problem during prolonged sampling
periods at commonly encountered
concentrations. This problem is over-
come by sequential or intermittent
sampling, but the sampling surfaces
must be protected from wind im-
paction when not rotating. Several
methods have been devised for this
purpose. Rotating impaction sam-
plers are the most satisfactory sam-
pling devices now available for most
aeroallergens and are being used by
an increasing number of allergists,
public health agencies, universities,
and research groups.
Aeroallergens collected on sam-
pling surfaces are commonly identi-
fied and counted using an optical
microscope. Routine counting of a
single particle type such as ragweed
pollen may be readily accomplished
by unskilled workers, but critical
identification of many pollens and
347
PART X — ENVIRONMENTAL CONTAMINANTS
Figure X-10 — EFFICIENCY OF CYLINDRICAL COLLECTORS
FOR RAGWEED POLLEN
100
80
70
60
Ml
40
30
20
10
One mm, diameter cylinder
One mm. middle section of one-fourth inch diameter cylinder
> One-fourth inch diameter cylinder
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
WIND SPEED IN METERS PER SECOND
The graph shows a plot of impaction efficiency in percent versus wind speed in
meters per second for three different-sized cylinders. The smaller the diameter of
the collecting cylinder, the higher the impaction efficiency because the stagnation
region in front of the cylinder is physically smaller and the particles need less
inertia to penetrate it. To overcome the variability in wind speed and wind direction
in nature and to operate the samplers at optimum impaction efficiency, samplers
are rotated to simulate wind speeds of 10 meters or more per second.
spores requires highly trained ex-
perts. At times, concentrations, not
only of the species of interest but
also of other materials, may be so
high that counting becomes difficult
and time-consuming. This problem
is multiplied when samples are
counted for many or all species pres-
ent. Visual counting is a tedious
chore at best, but automatic counting
devices have not yet proved their
ability to differentiate and count
aeroallergens.
Representativeness — Aeroaller-
gens are commonly sampled at a
single point over some pre-selected
time period, often twenty-four hours.
The spatial representativeness of
single-station sampling has been little
investigated, but it is known that
proximity to sources, elevation above
the ground, and presence of obstacles
to airflow can produce wide differ-
ences in catch over short distances.
Even two identical samplers operated
side by side may often differ by 10
to 20 percent and sometimes by 50
percent. If concentrations are meas-
ured over some time period, they may
not represent concentrations over ei-
ther a longer or a shorter time period.
Thus, even a perfect sampler could
only measure the mean concentration
over some time period at a specific
location; extension of the measure-
ment to other locations or periods
would be accompanied by some un-
certainty.
Requirements for Scientific Study
Sampling of aeroallergens, study
of their behavior in the atmosphere,
correlation of their presence and
abundance with other pertinent vari-
ables, and application of the knowl-
edge gained to the pollinosis problem
would be greatly facilitated by the
development and use of better sam-
pling devices. An ideal sampler
would sample the atmosphere non-
selectively, capturing particles of all
sizes and shapes with equal and
known, although not necessarily per-
fect, efficiency. The samples should
also be collected in such condition
that identification, counting, and
analysis would not be more difficult
than with present samplers. Ob-
viously, such a sampler would have
wide application in sampling air pol-
lutants of all types. Attempts to de-
velop two samplers having these
characteristics are in progress at
Brookhaven National Laboratory but
neither is yet operational. Further
research and development on sam-
pling methods are needed.
Until improved samplers are de-
veloped, rotating impactor samplers
will remain the most quantitative
method of sampling aeroallergens.
Only one of these, the rotoslide, has
been tested under controlled condi-
tions for collecting efficiency for rag-
weed pollen. Efficiency determina-
tions for the rotoslide and the other
rotating impactor samplers should be
made for a wide range of pollen and
spore types and sizes. More research
is also needed to determine the best
available adhesive for these samplers
and to develop better methods of
application.
Since the efficiency of impaction
samplers is a function of particle
characteristics, these should be de-
termined for at least the more com-
mon aeroallergens. Most needed are
measurements of pollen and spore
density, but changes in size, density,
and the state of conifer pollen blad-
ders with age and humidity also need
investigation.
Studies are also needed to assess
the temporal and spatial representa-
tiveness of single-station samples as
a function of surroundings (terrain,
vegetation, and man-made structures),
distance from sources, meteorological
348
AIRBORNE BIOLOli RIALS
variables, and particle type. Such
studies would permit estimation of
the probable range of error caused by
considering a sample representative
of a wider region or a different time
period. Peak-to-mean concentration
ratios should be studied so that short-
period concentrations can be esti-
mated from longer-period means with
some statistical reliability.
Finally, the efficiency of the human
nose as an aeroallergen sampler
should be investigated to aid in relat-
ing measurements of ambient con-
centration to allergic symptoms. Some
allergists believe it is more important
to determine what is being inhaled
than to determine accurately what is
in the air. A sampler simulating the
human breathing and retention mech-
anisms should be worth developing.
Further studies involving aeroaller-
gen sampling that might be expected
to result in advances in knowledge
and methods include:
1. Studies of the relationships be-
tween aeroallergen concentra-
tions and pollinosis or other
health effects.
2. Studies of the effect of weed-
control programs on local con-
centrations of an aeroallergen.
Such studies should include
adequate before-and-after sam-
pling with appropriate sam-
plers. Weed-control programs
would not seem useful unless
preliminary measurements of
both locally produced pollen
and that transported into the
area from outside sources indi-
cate that reduction of locally
produced pollen would cause
a medically significant decrease
in over-all concentrations.
3. Studies of the production, re-
lease, transport, dispersion, and
removal of aeroallergens from
known sources.
4. Studies designed to evaluate
the efficiency of natural par-
ticle-removal mechanisms such
as washout by precipitation or
impaction by vegetation (green-
belts, shelterbelts, or forests).
5. Surveys of the incidence and
concentration of aeroallergens
as a function of time, meteoro-
logical conditions, and other
pertinent variables.
Since individual allergists and their
societies have shown a marked reluc-
tance to adopt new and improved
methods for sampling aeroallergens,
public agencies should set an example
by taking the lead in using and
recommending the most appropriate
of these devices.
349
PART X — ENVIRONMENTAL CONTAMINANTS
3. PESTS AND PESTICIDES
Environmental Pollution and Pesticides
The history of man is a history of
his modifying his environment to
suit his own needs and desires for
food, shelter, and the pleasures of
his own leisure. Primitive man lived
as an integral part of the living and
nonliving environment, but as his
proficiency to further his own ends
has advanced, he has progressively
taken on a more dominant, displacive
role. Because of his success and his
awesome technology for modifying
the world in achieving that success,
man now faces the dilemma that if he
proceeds as he has been he will de-
stroy or greatly lessen the earth's
capacity to sustain life, himself in-
cluded.
Shortcomings of Present
Technology
Among his technologies, some of
which embody greater attacks on the
biosphere, man has developed an
"advanced" technology of pest con-
trol. This technology can only buy
time while we find a solution to the
main problem of human population
growth and establish a redirection
of all our technologies along more
compatible ecological lines.
Pest-control technology, through
use of modern synthetic chemical
pesticides, achieved a high degree of
perfection in terms of control of in-
sect pests for a time. It was, however,
developed single-mindedly with no
real regard for ecological conse-
quences. It was based on the stag-
geringly false cliche that "the only
good bug is a dead bug," and on the
incomprehensible premise that each
pest problem is a separate one — with
no entangling feedback loops disturb-
ing to crop-protection objectives.
Thus, we have developed deadly,
broad-spectrum, persistent pesticides
and used them too indiscriminately
and in ignorance of, and disregard
for, ecological consequences of vital
concern, often creating pest situa-
tions worse than the original ones,
to say nothing of ancillary problems
of much importance.
Among the adverse consequences
of a single-objective pesticide tech-
nology are:
1 . Resistance has developed in
many target species. (See Fig-
ure X-ll) The more rapid the
resurgence, the more rapidly is
resistance developed; and re-
sistance to alternate materials
then used often develops even
faster.
Most materials are nonselec-
tive, directly affecting the nat-
ural enemies of the target pest,
often more so than the pest.
Rapid resurgence of the pest
species then occurs.
Destruction of key natural en-
emies can be indirect, through
too severe destruction of the
target pest itself (the enemies
starve out) and through de-
Figure X-11 —RESISTANCE OF INSECTS AND MITES TO PESTICIDES
1910
1920
1930
1940 1950
YEARS
1960
1970
1980
The graph shows that the number of resistant species has been increasing rapidly
since the early 1950's and now stands at about 240. The changes in pest species
that allow them to survive at higher and higher concentrations of insecticides are
genetic and result from natural selection. Unfortunately, the graph tells the story
only of known pests. Large numbers of insect species that have not been examined
are subject to the same selection for resistance. When and if these insects erupt
as agricultural pests, they will already possess a significant resistance to pesticides.
350
STIC1DES
struction of some alternate prey
species, perhaps of no economic
importance. This can lead to
resurgence.
4. Previously secondary pests or
entirely innocuous species are
commonly unleashed; this has
usually been due to disturbing
effects on their natural enemies.
5. Destruction of honey bees and
other important pollinating in-
sects.
6. Hazards to the applicators
(many deaths and much sick-
ness).
7. Hazard to crop culture on the
same ground (overload of per-
sistent pesticides in the soil,
etc.).
8. Immediate hazards to man and
wildlife that enter the treated
areas.
9. Hazards to nontarget orga-
nisms in places well removed
from the treated area. This in-
cludes significant influences on
birds like pelicans, ospreys, and
eagles that feed high on the
food chains and especially on
ones living around estuaries
where DDT, for example, is
concentrated; on important es-
tuary anthropods; on grazing
livestock and even man himself
as a result of residues on crops
or range or in fish, etc. DDT,
for example, has moved widely
in the biosphere — it is found in
sea life at the antarctic. Drain-
age of pesticides into lakes and
rivers has caused great kills of
fish and much public alarm.
The herbicide 2,4, 5-T is appar-
ently being withdrawn from
the market for fear of adverse
effects on man and livestock
during pregnancy.
An Enlightened Technology —
Integrated Control
An enlightened pest-control tech-
nology is one that maximizes benefit/
cost relationships and minimizes en-
vironmental degradation. The philos-
ophy and methodology of integrated
control aims to this end.
The weather is a powerful mor-
tality factor for many pest species,
but we cannot manipulate the
weather. Natural enemies of pest
species are nature's own pest-control
specialists, and their use causes
neither outbreaks of innocuous spe-
cies nor environmental degradation.
Moreover, such species are quite
manipulatable. Their great impor-
tance in general is suggested in the
very fact that secondary and formerly
innocuous species are unleashed and
become serious pests when disturbing
pesticides are used. Why are only 2
of the 100 phytophagous species on
cotton in California found to be se-
rious pests? Why is our natural
vegetation so seldom grossly de-
voured by the myriad of phytopha-
gous species that attack it? Many
upsets have followed use of pesticides
in these situations and adverse effects
on natural enemies is considered the
usual reason. Natural enemies should
be explored in much greatt
the enlightened new pest-control
technology.
In spite of the repercussions from
unwise use of pesticides, pesticides
nevertheless remain a most useful
tool for managing our insect pests
in a manner compatible with this
objective. Use of selective pesticides,
selectively used, offers our best op-
portunity of making maximum use
of natural enemies, combined with
cultural methods, lures, and other
schemes. The development of a new
form of "biological" pesticide — i.e.,
hormones — offers new possibilities
of selective pesticides. During the time
we are learning to better use the resi-
dential natural enemies and finding
new and better ones for introduction,
or perhaps altogether new means of
pest control, pesticides will be espe-
cially needed. (See Figure X-12) We
do not now have adequate natural
enemies for all the major pests on
many crops (although this might
prove to be more nearly attainable
Figure X-12-
-PESTICIDE USAGE AND AG
RICULTUHAL YlhLU:
3
Pesticide Use
Yield
Area or Nation
Grams per
hectare Rank
Kilograms per
hectare
Rank
Japan
10,790 1
5,480
1
Europe
1,870 2
3,430
2
United States
1,490 3
2,600
3
Latin America
220 4
1,970
4
Oceania
198 5
1,570
5
India
149 6
820
7
Atrica
127 7
1,210
6
The table shows the close parallel between rank order of pesticide usage in selected
countries and areas and rank order of agricultural yield. Note, however, that Japan
produces twice as much food per hectare as the United States, but uses ten times
the amount of pesticides. Similarly, the U.S. has over twice the African yield per
hectare, but uses eleven times as much pesticide. The question is whether such a
high ecological cost for food production is unavoidable or the result of a particular
agricultural system.
351
PART X — ENVIRONMENTAL CONTAMINANTS
than many think) and we need selec-
tive use of pesticides to make the
best use of the ones we have.
In developing modern pesticide
programs, we need to consider the
following:
1. Complete control of the pest
is not essential or even desir-
able. Treatments can be re-
duced in number and dosage if
realistic economic-injury levels
are established; natural en-
emies are then left to dampen
resurgence tendencies and the
rise of secondary species, the
resistance problem is not ag-
gravated, and less toxic mate-
rial is added to the environ-
ment.
2. The faunal elements in the
environment are interrelated.
The biologies and roles of
seemingly insignificant species
may be a clue to effective use
of a natural enemy against a
major pest. Thus, in winter, a
tydeid mite is a significant al-
ternate for an important preda-
tor of spider mites on grapes in
the San Joaquin Valley in Cali-
fornia; here, too, the non-
economic leafhopper Dikrella
cruentata found on wild black-
berries is essential to the over-
wintering of the effective para-
site of the grape leafhopper,
Erythroneura elegantida, a key
pest of this crop. Planting
of small patches of blackberries
near extensive vineyards can
thus provide the ingredient for
control of the pest species on
grapes, and the cessation of
treatments for this leafhopper
can result in the natural solu-
tion of the spider-mite problem
that the pesticides induce.
3. Using the pesticide at the dos-
age and manner having the op-
timal effect in providing imme-
diate relief from damage but
causing a minimal ecological
disturbance may require a ma-
terial having some persistence.
Short-lived alternatives to some
persistent materials may be
even more objectionable, and
more repeated applications may
be required, thus magnifying
the problems.
4. If effective and practicable pes-
ticides should be used in spe-
cific parts of the environment
rather than as general coverage
materials.
5. Each pesticide should be ap-
praised separately and on the
basis of specific use unless, as
seems the case for DDT, the
general severity of the pollutive
accumulation in the environ-
ment justifies its demise (aside
from public health use in
heavily malarial areas, etc.).
6. Natural enemies, cultural meas-
ures, traps, and other feasible
nonpollutive measures should
take priority over use of pes-
ticides, with the latter used
to supplement them. Cultural
measures may include growing
of trap crops or ones harboring
alternate hosts of enemies, de-
struction of pest-harboring ref-
uges, use of planting dates, etc.
Releases of sterile insects or
use of genetic techniques should
be tried when promising for
a particularly difficult species,
where its solution would open
up avenues for better-integrated
control of the pest complex.
Releases of the pest itself, use
of strategic repetitive releases
of natural enemies, augmenting
techniques, and introductions
of new natural enemies should
be especially explored in depth.
It is a fallacy to think that,
since crops are highly artifi-
cial (unnatural) and grown as
simple monocultures, the laws
governing the balance of nature
and the role of natural enemies
are insignificant here. Complex
natural communities present a
more stable picture than sim-
pler communities because of
the greater diversity in trophic
links. Yet many of the species
of natural enemies accounting
for the low numbers of a po-
tentially disturbing (to the
community) phytophagous in-
sect are highly host-specific.
Such links (host and host-
specific enemy) are often trans-
ferred to crop situations. Some-
times the pest form has arrived
without the natural enemy.
Our best examples of biological
control have resulted from our
seeking out and introducing
such natural enemies.
Integrated control, a systems-
analysis approach, can be built on
the basis given above. The computer
is essential in systematizing informa-
tion and testing hypotheses of how
complex systems work so as to ar-
rive at proper manipulating strate-
gies, but it cannot substitute for
grass-roots information. Much grass-
roots input is needed before any
major complex case (crop) can be put
on a rational, predictable scheme of
management. Key natural enemies
commonly present a high degree of
predictability for certain major pests
(and others can be developed), thus
making it possible to develop the sys-
tem around such a central fact when
established. Moreover, we must go
on with the task of working out con-
trols while we are gaining additional
insights for a full systems-analysis
approach. In-depth study of faunal
relationships and crop phenology,
economic-injury levels, and the like
are musts.
For an integrated control scheme to
be fully effective in achieving the
goal described, a revolution in the
system of pest-control advisement is
essential, and this cannot be accom-
plished without massive training and
re-training of a corps of pest-control
ecologists (see below).
Moreover, the whole social, eco-
nomic, and cultural situation relative
to insects or insect parts in foods, as
352
PESTS AN ' !DES
well as the "cosmetic" pests and
others, needs changing. Unrealistic
marketing standards, consumer at-
titudes, government regulations, and
so forth perpetuate an unrealistic
demand for totally unblemished, in-
sect-free produce; this demand can
greatly complicate an otherwise real-
istic solution which could provide
high-quality produce and high yields
at reasonable cost.
The Status of Our Knowledge
The final result of the approach
described above should be an en-
lightened systems-analysis approach
to decisions on strategy and tactics
of pest control, with due allowances
(based on value judgments that so-
ciety will have to make) for the im-
pact each measure might have, not
only for the benefit/cost relationship
(to the grower and the consumer),
but for the quality of the environ-
ment (health, wildlife, aesthetic, etc.).
Research Needs — We need mod-
els for depicting the control of a com-
plex of pests on a crop. The modeling
of a single pest population in the field
has progressed rather far in a few
instances. There is, for example, a
model of a laboratory population of
a grain insect and its parasite over 23
generations, with remarkably good
prediction for the whole 23 genera-
tions — not just generation by genera-
tion. However, this is a simple two-
species system in a simple, constant
environment. In the field, we need
to gain similar insights into the whole
environmental complex (biotic and
abiotic), especially the natural-enemy
performances relative to the climatic
regime, the key pest species, and the
possible influences of given pesticides
on them (and on ones keeping the
innocuous species under control). We
also need better knowledge of the
phenology of the crop and cropping
practices relative to the pests. We
have only the roughest information
on the economic- injury levels for
any pest. Of the few we have studied,
the numbers of insects required to
cause economic injury are much
greater than previously considered.
This is prerequisite to using pesti-
cides wisely or in not using them and
relying more on natural controls or
cultural measures.
We need much greater emphasis
on means of augmenting the value
of natural enemies. Only a beginning
has been made relative to use of
strategic releases of both pest and
enemy species, adding supplemental
foods or alternate hosts for enemies
in the environment (or nesting sites
for avian predators of insects), or
using special strains or genotypes of
a natural enemy species. The intro-
duction of new natural enemies is a
vast, largely untapped resource. The
hesitancy in doing so, based on
theoretical considerations, is refuted
by the record of over seventy years;
moreover, new theory confirms past
policy and speaks for much wider
use of new introductions.
The main reason why more biolog-
ical control has not been accom-
plished is that vastly too large a por-
tion of available effort has gone into
work on pesticides in the area of
single-minded pesticide-use technol-
ogy. A disproportionate amount has
also gone into the development of
new ideas (e.g., use of releases of
sterile insects) that have succeeded
only to a very limited degree and
and do not offer prospects for wide-
scale commercial solutions. A record
of some 70 cases of complete biologi-
cal control and 250 with at least par-
tial success for the world is a for-
midable achievement in the light of
the effort that has been made on
biological control.
Economic and Political Considera-
tions— The pesticides that have been
developed are broad-spectrum ones,
which is natural since the industry has
been motivated by profit. Only token
consideration has been given to other
aspects (but more so relative to human
health). What is needed are pesti-
cides with selective activity — i.e.,
which act on a group of pe
with little effect on key natural i
groups. It is said to cost from t
million to $15 million to develop a
pesticide and market it. Many more
pesticides would be required for the
new technology, and sales of each
would be limited. The market price
would be high. The public must de-
cide if it wants the less pollutive tech-
nology badly enough to pay the price
in some form of subsidy to develop
these materials. Actually, such mate-
rials could be nearly self-supporting,
since the grower could afford a higher
price for them if his total usage of
pesticides is thereby greatly reduced.
Use of resistant hosts has been use-
ful in many instances and will be
again, but superimposing a pest-re-
sistance requirement on top of the
already staggering problems in devel-
oping high-yielding, good quality,
marketable cultigens means that this
solution is not likely to be a general
one.
Training Advisers — Lastly, we
need to change our whole system of
pest-control advisement. In the past
it has been based to a large extent on
profit from sales. The ecologically un-
trained, or even the ecologically an-
tagonistic, have often been used as
salesmen. There has been great pres-
sure on them to sell. They are the
closest "advisers" to the growers, who
in many cases have relied on them
heavily. Excessive concentration on
sales and too little attention to need
and consequences has led to the cur-
rent situation.
What is needed is a corps of well-
trained professionals who sell their
advice — i.e., advice not to treat as
well as to treat — but not the pesticide
itself. Thus, the system of advising
should be separated from profit from
sales. Since pesticides constitute a
poisonous factor in our environment,
reaching beyond the confines of the
area treated, it seems necessary that
society set up such a safeguard, as it
has long since in the dispensing of
353
PART X — ENVIRONMENTAL CONTAMINANTS
drugs for medicinal purposes. Whole
new programs of training pest-control
professionals who will do this advis-
ing are needed in the universities.
A General Perspective — It will be
necessary that adequate care is taken
to assure that the necessary changes
in philosophy and methodology are
made at each institutional level. The
old philosophy and methodology have
been entrenched for 40 years, and
nothing less than extreme action will
alter the picture fast enough.
At the same time, it is wishful
thinking to pin hopes on conceptually
intriguing new, but generally un-
proved, ideas of pest control — e.g.,
use of sterile insect releases, inunda-
tive parasite releases, genetic tech-
niques, hormones, special wave-
lengths, plastic exclusion airdomes,
and the like. A planned systems-
analysis integration of the long-
established techniques of biological
and cultural controls, and limited but
strategic use of selective chemical
controls, offers our best prospect of
solutions on a broad scale.
Pesticides and the Pollution Problem
In a broad and complete view of
pollution of the earth's biosphere,
pesticides are a minor element. Never-
theless, for certain local environments
or for certain endangered species, the
pollution from specific pesticides has
become a problem worthy of special
attention. In our general concern
about this pollution and in our re-
sponse to other undesirable effects of
certain pesticides, it is not rational
to condemn all pesticides. Further-
more, it is ill-advised to attempt to
ban all pesticides (even all persistent
pesticides) in the misguided hope that
this will protect birds and other wild-
life from the effect of man's disrup-
tion and pollution of the environment.
Even if all pesticide use were stopped,
other activities of man would cause
broad and sweeping disruptions of
his ecosystems and threaten many
forms of desirable life on this planet.
Uses and Limitations of Pesticides
Pesticides remain, in spite of ad-
verse publicity, man's most powerful
tool in the management and control
of pests. We have no choice, if we
insist on even minimal food, health,
and comfort, but to control pests.
The pesticides developed in the past
25 years are effective and economical
and can be marshalled quickly to
have immediate impact on a pest
population — even over a large area.
When pest populations approach eco-
nomic levels, there is little other than
pesticides that we can use to avoid
damage and which will have the de-
sired immediate effect. Hence, it
seems clear that pesticides must and
will continue to be used in a major
way in pest management.
The disadvantages or limitations
of pesticide chemicals are well known.
They have been so emphasized in
the press, on radio and TV, in politi-
cal arenas, and elsewhere that it is
now difficult to have a rational dis-
cussion that balances the beneficial
and the undesirable aspects of pesti-
cides. In brief review, the limitations
of pesticide usage are as follows:
1. Selection of pest strains that
are not controlled by usual
pesticide dosages.
2. Temporary effects on pest pop-
ulations necessitating repeated
treatment (often the pest popu-
lation quickly returns to a
higher level than before treat-
ment).
3. Hazards from residues of the
pesticide in the harvested crop.
4. Outbreaks of secondary pests
unleashed by destruction of
their natural enemies.
5. Undesirable effects on nontar-
get organisms, including (a)
parasites and predators; (b)
fish, birds, and other wildlife;
(c) honey bees and other nec-
essary pollinators; (d) man and
his domestic animals; and (e)
the crop plant.
o. Direct hazards to man during
the application of pesticides
and subsequently in the treated
area.
7. Reduction and simplification of
the biotic component of the
agro-ecosystem.
Factors Affecting Pesticide Use
This formidable list makes it nec-
essary to re-evaluate carefully the
appropriate use of pesticides. It also
serves as a basic guide to the im-
proved use of pesticides for pest
management and control. If we can
devise procedures for the use of
pesticides which will avoid or mini-
mize these disadvantages or com-
plications, then we will have devel-
oped an improved, perhaps even an
ideal, methodology for the efficient
and effective use of pesticides.
Destruction of Natural Enemies —
Ecologists concerned with the control
of pest insects have for some time
been alarmed at ecological disturb-
ances in agro-ecosystems engendered
by the unwise use of pesticides.
These are caused by the unintended
destruction of natural enemies, which
in turn results in rapid resurgence
of the target pest species or a sec-
ondary outbreak of an unleashed but
formerly innocuous insect. For ex-
354
PESTS AND PESTICIDES
ample, where a broad-spectrum pes-
ticide is used (and natural enemies
of the pest are also eliminated) or
when high dosages of a selective ma-
terial are used that kill off high per-
centages of the pest (and thus starve
out the natural enemies by eliminat-
ing their food), the pest populations
can recover quickly without hin-
drance of natural enemies.
This destruction of natural ene-
mies, as an unfortunate side effect
of pesticide usage, has two main
consequences. First, the target pest
may quickly recover from the impact
of pesticide usage and resurge to even
higher levels. (See Figure X-13) Sec-
ond, the resurgence of unleashed
secondary pests may occur shortly
after the application of the triggering
pesticide, or later in the growing sea-
son, or even in a subsequent season.
In cotton in California, for example,
we have had serious outbreaks of
such unleashed secondary pests as
beet armyworm, cotton-leaf perfora-
tor, and cabbage looper. These sec-
ondary pests may be more destructive
and more difficult to control than the
original target pest. Re-establishing
the effectiveness of natural enemies
may require two or more years.
Health Hazards — It is obvious that
we should not knowingly use pesti-
cides in ways that would constitute
a risk to human health. Such hazards
can occur to the individual applying
the pesticide, or to persons entering
the treated area either during the
application or at some appreciable
time later, or to persons exposed to
the residues of the pesticide on or
in the harvested crops, or in other
more subtle ways. When such a
hazard is discovered, procedures
should be taken to avoid the risk —
Figure X-13 — RESURGENCE OF CALIFORNIA RED SCALE
Population Density-
-California red
scale
Orchard
No.
Locality
li
nitial
Final
DDT-
treated
Un-
treated
DDT- Un-
treated treated
1
Irvine, Orange Co.
0
2
125
3
2
Sinaloa, Ventura Co.
35*
46*
572
17
3
Sespe, Ventura Co.
1
1
425
7
4
Biological Control Grove
UCR, Riverside Co.
8
2
246
8
5
Birdsall, San Bernardino Co.
0
0
67
6
6
Beemer, San Diego Co.
4
5
158
3
•Initially heavy, due to previous upset by ants. Ants were controlled subsequently.
The table shows differences in the density of California red scale between trees
left under normal biological control and some experimental citrus groves treated
with DDT. The initial counts, comparable in both sets, were made just before DDT
was applied; the low ratings (mostly 10 or less) indicate that the scale was scarce
and under an excellent degree of natural control. After one or two seasons of
treatment with DDT, however, red scale was far more common, whereas the scale
on the untreated trees was evidently held in check by natural enemy activity.
Ratings above 50 to 100 begin to cause visible, and economically unacceptable,
twig and branch kill.
e.g., proper masks and clothing for
applicators, minimum time period af-
ter treatment before the treated area
can be entered, or minimum time
after treatment before harvest. In
those instances where the risk can-
not be avoided, then use of that
particular pesticide should be cur-
tailed and a suitable alternative con-
trol measure sought. This is not to
suggest that all uses of the pesticide
be banned but rather that the par-
ticular hazardous uses be eliminated.
Furthermore, when alternatives are
considered, all aspects, both positive
and negative, should be carefully
weighed.
Limitations of Substitute Mate-
rials — In the past year or more, there
has been considerable public pressure
to eliminate all persistent pesticides.
Let us not forget that, if this comes
about, society is losing valuable tools
for pest control and that there are
other problems associated with many
of the substitute materials. Basically,
each compound should be considered
individually as to its peculiar risks on
the basis of its specific characteristics
together with the exact manner of
dosage and place of application.
To date, the substitutes have usu-
ally been either organophosphorus
compounds or carbamates, though it
is difficult to generalize because there
are so many exceptions. The sub-
stitute materials used so far have
shown, first, a frequent pattern of
higher acute toxicity, with associated
greater immediate risk to man, live-
stock, and wildlife. Secondly, these
substitute compounds frequently have
produced serious damage to honey
bees and other necessary pollinators;
their impact on the California bee-
keeping industry has been disastrous.
Thirdly, they have had a severe im-
pact on insect natural enemies. As
noted above, elimination of natural
enemies from treated areas frequently
permits rapid resurgence of the target
pests and outbreaks of previously in-
nocuous species. Finally, the short-
lived nature of the substitute mate-
rials together with their side effect
355
PART X — ENVIRONMENTAL CONTAMINANTS
on natural enemies requires repetition
of applications. This increases the
selection pressure for resistance in
some cases and hastens the develop-
ment of populations resistant to the
chemical.
Persistence of a pesticide chemical
is not in itself an undesirable quality.
Normally, we need some level of per-
sistence for pest control. This is es-
pecially true when the pest popula-
tion moves slowly into a susceptible
stage of development or out of hiber-
nation quarters or other inaccessible
or unbeatable habitats into the area
of contact with the pesticide. If the
movement into the area to be pro-
tected extends over an appreciable
length of time, the pesticide must
persist over this length of time or
else repeated treatments with a non-
persistent material will be necessary.
In general, the latter procedure will
be more costly and more hazardous.
Persistence is a disadvantage when it
is the cause of undesirable residues
on the harvested crop or elsewhere
in the agro-ecosystem, or when the
pesticide is concentrated through food
chains to harmful levels in non-target
organisms. (See Figure X-14) Again
we must strike a balance between
costs of alternative procedures and
between the benefits and undesirable
effects of these procedures. This com-
parison should not be made only in
narrow economic terms but also with
full consideration of the social costs
and benefits.
Guidelines for Good
Pest Management
Today many decisions with respect
to pest control are being made in a
political context and with little con-
sideration of the fundamental tech-
nological facts upon which sound
pest-control decisions should be
based. Each pesticide usage should
be judged on the basis of the poten-
Figure X-14 — CONCENTRATION OF DDT
IN A LAKE MICHIGAN FOOD CHAIN
DDTinppm
Water
0.000002
Bottom mud
0.014
Fairy shrimp
0.410
Coho salmon,
lake trout
3-6
Herring gull
99
The table shows why minute quan-
tities of DDT in lake water are a
serious problem. The rate of ac-
cumulation is proportional to the
concentration of DDT in the water
multiplied by the time of exposure.
By the time DDT reaches fish, its
level of concentration can cause
reproductive failure. These con-
centrations in the fish in turn be-
come a hazard to the piscivorous
birds at the top of the food chain.
Retention time for DDT in water
averages 30.8 years. No solution
to the problem is yet evident.
tial positive values to be achieved
by such usage as weighed against
the possible negative values occurring
from residues on the harvested crop,
occupational hazards to humans, haz-
ards to pollinating and other benefi-
cial insects, effects on wildlife, the
contribution to total environmental
pollution, and other direct or subtle
effects. Each use of a chemical must
be judged independently. Banning
all uses of a chemical is unwise unless
it is clear that all uses of that chemi-
cal are harmful. Likewise, it is ir-
responsible to advocate the total
replacement of pesticides with so-
phisticated but poorly tested alterna-
tive pest-control techniques. It is a
disservice to society to discard the
good crop-protection methodology
currently available and to adopt in its
place a glamorous new but untested
methodology. In the future develop-
ment of crop protection for a world
agriculture, it will be just as impor-
tant to apply the methodology of
traditional pest-control techniques as
it will be to find revolutionary new
approaches, some of which may be
expected to have little or no practical
value.
Research — In the interest of a bet-
ter environment, the integrated con-
trol concept must be fostered among
pest-control researchers, and research
on pest-management systems should
expand as rapidly as possible. There
is a critical need for information on
many aspects of integrated control,
including pest economic thresholds,
natural control, ecology, phenology,
and the nature of agro-ecosystems.
Such studies will provide informa-
tion permitting better timing and
placement of insecticidal treatments
and will lead to the development of
alternative control measures. Studies
of this sort are currently being sup-
ported by federal and state agencies
and some of the commodity groups,
but the need exists for greatly ex-
panded support.
Manpower Training — The more
sophisticated controls and integrated
control systems will create a demand
for more highly qualified people in
pest control. Consequently, there is
an urgent need to develop, simultane-
ously, training programs for ecologi-
cally oriented pest-control advisers.
Practicing economic entomologists
versed in the principles of integrated
control are extremely rare today and
badly needed for an ecological ap-
proach to pest control. The training
of a new corps of researchers and
advisers well versed in integrated
control will entail careful planning
and the development of a new type
of curriculum.
356
4. MARINE CONTAMINANTS
Effects on the Ocean of Atmospheric
Circulation of Gases and Particulate Matter
The transport of materials from
the continents to the marine environ-
ment takes place primarily through
wind, river, or glacial systems. The
activities of man have added two
other paths: (a) introduction, both
by intent and by accident, from ships
and domestic and industrial sewage
outfalls, and (b) introduction by man
of materials to the atmosphere, with
subsequent impact upon the oceans.
The latter path will be emphasized
here.
Aerial transport can result in the
rapid and widespread dispersal of
solids, liquids, and gases. For ex-
ample, radioactive debris in the
troposphere from the Chinese nuclear
device tested in 1965 fell back to
earth in a latitudinal band following
its transport in the jet streams; these
materials circled the world twice with
an average velocity of 16 meters per
second.
The ocean acts as a reservoir for
the dissolved phases introduced to
it and maintains them for periods
of the order of centuries to thousands
of millenia. Thus, the impacts of man
upon the seas, if measurable today,
will also be measurable many, many
generations into the future.
There are probably three major re-
sponses by the environment to such
impingements by man: alteration of
its physical nature, alteration of cli-
mate, and alteration in the constitu-
tion of communities of organisms.
Although some of the changes are
quite difficult to detect today, none-
theless, on the basis of our knowl-
edge of the types and amounts of
materials being dispersed to the air,
there is hope for some predictions.
Impact of Man-Made Materials
Managing the discharge of mate-
rials to the atmosphere will take on
greater importance with time as both
population and the material and en-
ergy utilizations per capita increase
in the world. We have successfully
managed, so far, the releases of
radioactivity to the environment from
nuclear reactors. On the other hand,
we have had serious problems with
the disposition of pesticides to our
surroundings; clear-cut impacts on
the communities of birds have been
felt. The definition of critical prob-
lems in atmospheric release of solids
and gases such that appropriate ac-
tions can be taken by policymaking
bodies is clearly the end-point of the
considerations presented here.
Metals — The identification of the
materials from fuel combustion and
from industrial production is incom-
plete, especially with regard to the
latter category. Metals such as mer-
cury and arsenic, which have volatile
forms, are entering the atmosphere —
and subsequently the oceans — as a
result of mining and extractive metal-
lurgical, industrial, and agricultural
operations. High concentrations of
atmospheric mercury accompany the
smog in the San Francisco Bay region.
High arsenic contents of Japanese
rain waters have been attributed to
the smelting of sulfide ores and fuel
combustion. The flow of such sub-
stances through our surroundings is
poorly defined. About 2.5 percent
of the total production of gasoline
is lost by evaporation during trans-
fer processes, from production site to
vehicles and to storage tanks and
through vaporization from the auto-
mobile gas tank and carburetor. This
amounts to several million tons per
year throughout the world. Again,
the subsequent activities of this gas-
oline in the air are as yet undeter-
mined.
Chemicals — Volatile synthetic or-
ganic chemicals are dispersed about
the atmosphere and their impacts are
still described inadequately. The
losses of dry-cleaning fluids and
freon, though not necessarily the
most important emissions, are none-
theless illustrative of the types of
material flows that should be studied.
The evaporation of dry-cleaning sol-
vents must be of the same order of
magnitude as their production — sev-
eral hundred thousand tons per year.
The most widely used substance is
perchloroethylene.
A similar amount of dichloro-
difluoro-methane (Freon-12) enters
the air following its use as a propel-
lant in the bombs containing shaving
cream, deodorants, paints, and so on.
Do such materials retain their iden-
tity before entering the oceans or
are they degraded as atmospheric
gases? The gas chromatograms of
liquid air condensates from the at-
mosphere contain many unidentified
peaks, perhaps volatile synthetic or-
ganic compounds. A systematic in-
vestigation of possible inputs, based
on production figures and field ob-
servations, would be most rewarding.
Fuels — The greatest single source
of man-introduced materials to the
environment encompasses the prod-
ucts resulting from combustion of
the fossil fuels — coal, oil, and natural
gas. Since 1850, the amounts burned
have doubled about every fifteen to
twenty years. Carbon dioxide is the
principal gas released in such proc-
esses; its rate of increase at the pres-
357
PART X — ENVIRONMENTAL CONTAMINANTS
ent time is 0.8 parts per million per
year for an atmosphere containing
about 320 parts per million. About
40 percent of the carbon dioxide so
introduced still remains in the atmos-
phere.
The main sink for this added
carbon dioxide has not yet been es-
tablished, although it is most prob-
ably the deep ocean. There have
been suggestions that land plants,
through more extensive growth, have
accommodated this additional carbon
dioxide. Whether such introductions
have increased plant productivity in
the sea through the input of addi-
tional carbon dioxide to the surface
waters and whether the earth's tem-
perature has increased through the
"greenhouse effect" created by this
excess carbon dioxide are questions
not yet resolved.
The search for the sinks of the
products of fossil-fuel combustion
has widened our knowledge of nat-
ural phenomena. For example, at
one time it was thought that the
fate of carbon monoxide, resulting
from the incomplete combustion of
fossil fuels, was either an atmospheric
oxidation or an uptake by seawater.
Surface seawaters have carbon mon-
oxide concentrations ten to forty
times higher than atmospheric equi-
librium values and the marine en-
vironment turns out to be a source
for carbon monoxide. Mid-tropo-
spheric concentrations in the sub-
tropics display no marked differences
between the two hemispheres, indi-
cating that the source of the carbon
monoxide is natural and that the
atmospheric lifetime of the gas is
of the order of a year or longer.
Higher values of carbon monoxide
have been found in the air over open
ocean waters as compared to the air
over bay and river waters.
Preliminary calculations of the
oceanic output give a value of the
order of ten million tons per year,
about five percent of the 200 million
tons annually generated by the burn-
ings of fossil fuel. The sources of the
carbon monoxide in the oceans are
probably biological — through the
bacterial or photochemical oxidation
of organic matters in surface waters or
through the direct production by
marine algae, "Portuguese Men of
War," or siphonophores.
The disposition of the carbon
monoxide in the atmosphere is not
yet known. The principal sink will
probably turn out to be stratospheric
oxidation by OH, H-O.., or HO- radi-
cals. Another possible fate of the
carbon monoxide may be an oxidation
to carbon dioxide by soil bacteria.
Insights into Natural Processes
The researches with carbon mon-
oxide illustrate a common result
of environmental studies — we learn
about natural processes through in-
vestigations of pollutants. Such was
the case with the radioactive species
introduced through the detonation of
nuclear devices both in the atmos-
phere and in the oceans; our knowl-
edge of mixing processes within these
two geospheres was decidedly en-
hanced. In addition, marine eco-
logical research has been sponsored
primarily by atomic-energy agencies
that are concerned about the inter-
actions of radioactive species pro-
duced by fusion and fission reactions
with members of the biosphere.
Complementarily, guidance as to
the fates of man-introduced materials
to the atmosphere-ocean system can
come from knowledge about the nat-
ural substances involved in the major
sedimentary cycle.
Atmospheric Transport — Over the
past decade, the transport of solids
to the marine environment by at-
mospheric paths has become a most
attractive area of research. More than
a century ago, Darwin had suggested
that major expanses of sediment on
the open ocean sea floor are the result
of an atmospheric transport from
continental arid regions. Yet only
recently have we been able to state
with some confidence that most sedi-
mentary solids in the North Pacific,
North Atlantic, and Arabian Sea are
derived from the continents by wind
transport. Perhaps more important
is the observation that the geographic
distribution patterns of diagnostic
minerals in the deposits moderately
well define the bounds of the wind
systems. For example, in the North
Pacific the concentration gradients of
the clay mineral illite and of quartz
in the sediments closely parallel the
gradients in the intensity of the jet
stream averaged over a year. Simi-
larly, off the west coast of Australia,
the prevailing southeasterly winds
are recorded in the sediments by high
concentrations of the clay mineral
kaolinite that they carried from the
Tertiary laterite deposits on land.
Atmospheric Dust — Removal of
solids from the atmosphere takes
place through scavenging by precipi-
tation, rain, snow, sleet, and rime
and by gravitational settling, with the
former process being the more im-
portant. Since the average time be-
tween rains in many parts of the
world is counted in weeks, transport
of suspended particles can take place
over great distances. Dust collected
on the island of Barbados originated
in the European-African continents
with a transport by the northeast
trade winds. Such materials were
also picked up further along their
transport path in the glaciers of
Mexico.
The industrial activities of civiliza-
tion are recorded in such dusts. Many
atmospheric solid samples collected
in the Atlantic are gray to dark gray
in color due to pollution by carbon
and fly-ash spherules. Increases in
the rate of dust accumulated in the
Caucasus glaciers have been related
to the mechanization and indus-
trialization of eastern Europe. The
dust accumulation rate clearly shows
marked increases beginning in 1950,
which parallels the growth in the
Soviet economy. (See Figure X-15)
Possibly, a more pertinent case for
the impact of man upon the marine
358
MARINL CONTAMINANTS
Figure X-15 — COMPARISON OF CAUCASIAN DUST FALL
AND THE SOVIET ECONOMY
240
160
E
80
DUST FALL IN CAUCASUS
AMOUNT IN CAPITAL STOCK
III
250
1930
1940
1950
1960
The diagram shows a close correspondence between (a) measurements of fallout
of atmospheric dust in milligram per liter, as measured in glaciers of the Caucasus
mountains, and (b) the amount of capital stock (equivalent inventories, building and
livestock) in the Soviet economy expressed in billions of 1937 rubles.
environment may be seen in the find-
ing of talc as a common constituent
of atmospheric dusts. This mineral
is rare in land soils, but appeared
ubiquitous in solids collected from
air masses, as well as in glacial snows
deposited before 1946. This talc
arises from its use as a carrier and
diluent for pesticides in surface and
aerial spraying of agricultural crops.
Direct measurements of chlorinated
hydrocarbon pesticides and their resi-
dues have followed the discovery of
talc in these domains. Comparisons
of the contributions of river-borne
and atmospherically transported pes-
ticides to the marine environment
have been made and both appear to
be of the same order of magnitude.
The atmospheric estimates based on
particle collection are clearly under-
estimates, inasmuch as some of the
pesticides are carried to the marine
environment in the vapor phase.
Nonetheless, these mechanisms for
conveying pesticides to areas of the
oceans where river influxes appear
to be slight do explain the increasing
levels of chlorinated hydrocarbons
appearing in birds and fish.
Interactions of Contaminants and
the Atmosphere-Ocean System
The interactions of airborne con-
taminants with the marine biosphere
are more speculated upon than estab-
lished. The scientific literature is re-
plete with tales of woe concerning
the possible effects of pesticides on
the photosynthetic activities of marine
algae and a consequential loss of oxy-
gen from our atmosphere. Recent
investigations do indicate that photo-
synthesis and growth of some species
of marine phytoplankton can be ad-
versely affected by exposure to chlori-
nated hydrocarbons; others show a
complete insensitivity. But to ex-
trapolate such findings to a possible
elimination of all photosynthetic ac-
tivity in the oceans appears un-
warranted, inasmuch as the factors
governing the gross production of
organic matter in marine plants are
still incompletely determined.
On the other hand, present-day
experimental and monitoring data do
suggest that there is a significant
decrease in the productivity of estua-
rine fish and shellfish as a result of
the ingestion of DDT and its residues,
some of which is airborne from the
continents. Further, it appears that
the resistant surviving animals are
able to concentrate and transmit toxic
quantities of these residues in the
food chain. The reproductive suc-
cesses of seabirds has decreased due
to interferences with their normal cal-
cium metabolism by the high body
burdens of these halogenated hydro-
carbons. These birds, feeding on
marine fish, are at the upper levels
in the food chain. The marine fish are
building up levels of these pesticides
that equal, and sometimes exceed,
those of their freshwater counter-
parts. The ocean waters act as a
reservoir for these river- and wind-
transported materials, while the re-
birth of rivers every year often results
in lower concentrations even though
the rivers are closer to their points
of origin.
These studies with DDT and its
residues are providing a most impor-
tant pattern to study the polycholori-
nated biphenyls (PCBs) — another
industrial chemical group, most prob-
ably dispersed through the atmos-
phere, that is appearing in marine
fish and birds. Manufactured since
1929, PCBs are used as plasticizers,
transformer fillings, solvents for
359
PART X — ENVIRONMENTAL CONTAMINANTS
paint, and components of caulking
materials. They probably behave
similarly to the halogenated hydro-
carbons in organisms, and there is
great concern over their buildup in
the marine environment. (See Figure
X-16) Such materials will receive a
good deal of attention in the coming
years. But of greater importance will
be the identification of other chemi-
cals that are building up in organisms
of the sea and that are capable of
altering their life processes.
Deleterious effects due to the entry
of man's artifacts to the atmosphere-
ocean system have been documented
in only a few cases, such as those of
pesticide residues on the reproductive
success of some marine birds. We
can expect other catastrophic episodes
in the future, however. To react
rationally and effectively to such
events and to minimize their recur-
rences, it will be important to have a
past record of man's inputs to his
environment, especially of substances
that we do not now monitor for one
reason or another.
Use of Glaciers in
Atmospheric Monitoring
The idea of utilizing permanent
snowfields (glaciers) to provide such
information is not new. Yet researches
on the glacial records of man's activi-
ties at the earth's surface have so far
been small and limited, even though
permanent snowfields exist below all
of the major wind systems and main-
tain sequential records of atmospheric
fallout for centuries and even for mil-
lenia. Work on lead concentrations
in ice layers from northern Greenland
and from the interior of Antarctica
have shown increases beginning at
800 b.c. to the present, with the
sharpest rise occurring after 1940.
These increases are ascribed mainly
to lead smelteries before 1940 and
to burned lead tetra-ethyl and lead
tetra-methyl in internal combustion
engines after 1940. In both cases,
lead was introduced to the atmos-
phere and brought back to the surface
of the earth primarily in precipitation.
The surface sea waters today show
much higher lead concentrations than
their deeper counterparts, an effect
that diminishes as the open ocean is
is approached. Predictions as to the
future lead concentrations in the
ocean can be made on the basis of
extrapolated industrial activity and of
models of the oceanic mixing proc-
esses. Very important is our knowl-
edge of the wind transport of lead
aerosols in the past through our read-
ing of the glacial record.
The concept that the amounts of
pesticides contributed to the tropical
Atlantic by the trade winds are com-
parable to those carried to the sea by
major river systems was triggered by
analyses of both pesticides and their
carrier talc in permanent snowfield
records as well as in direct analyses
of river and atmospheric samples.
Finally, the glaciers have recorded
the inputs of sulfur dioxide to the
atmosphere through the burning of
fossil fuels. The excess sulfur in the
atmosphere is now at least several
times natural levels.
Examples such as these point out
one most important direction to go
for obtaining benchmark data to study
man's relationship to the chemistry
of the surface of the earth.
Figure X-16 — PCB RESIDUE IN FISH, BIRDS. AND MAMMALS
Type
Organ
Location
Concentration (ppm)
Herring
Fat
Baltic
0.5-23
Salmon
Eggs
Sweden
7.7-34
Pike
Muscle
Sweden
6.0-48
Eider duck
Liver
Holland
2.1-96
Heron
Liver
Britain
0-900
Heron
Fat
Stockholm
9,400
Dolphin
Fat
Sargasso
33
Seal
Fat
Baltic
16-44
The table shows the ranges of concentration in parts per million that have been
measure in various organs of several species of fish (cf., Figure X-14 for DDT).
PCB's are not destroyed by usual waste-disposal methods. They enter the aquatic
environment through sewage effluents, land runoff from industrial wastes, and
condensation following incineration. PCB's have properties similar to DDT, but
they are more persistent and stable.
360
Oil on the Sea Floor
IVIAKilNL l^WIN 1 A1V111NA1N I 3
Recent observations concerning the
fate of oil in the ocean after spills and
leaks such as those in the Santa Bar-
bara channel and from the S.S. Torrey
Canyon off the English coast have led
some investigators to conclude that
dispersal methods that involve re-
moving the oil from the surface by
overpowering its natural buoyancy
(thus transferring it to the sea bot-
tom) are potentially more harmful to
the environment than methods that
leave the oil dispersed but floating on
the ocean surface.
Since sinking methods involve the
use of extremely cheap agents (sand,
ashes, and the like) and since they
generally remove the oil before it can
contact beaches, yacht hulls, and
other recreational surfaces, there are
strong economic and aesthetic argu-
ments in favor of their continued use.
On the other hand, if it could be
shown that the transferral of toxic
petroleum constituents to the sea floor
would result in damage to demersal
fisheries, there are strong arguments
for establishing an effective interna-
tional regime to control both drilling
for and seaborne transportation of
petroleum, wherever the possibility
exists that it may be deposited in
quantity upon the sea surface, and to
fix responsibility, assess damages, and
compensate those economically in-
jured in case such an event occurs.
Status of Scientific Knowledge
Current scientific knowledge rele-
vant to the problem of petroleum on
the sea surface and sea floor is far
from adequate with respect to reliable
predictions of the possible harmful
effects of removing petroleum or
petroleum residues from the sea sur-
face by sinking them to the sea floor.
Amounts of Hydrocarbons in
Marine Sediments — We do know
already, from extensive investigations
of the chemical composition of ocean
sediments in many parts of the world,
that detectable quantities of paraffins,
aromatics, and asphalts — chemically
indistinguishable from petroleum
fractions — are present in ocean sedi-
ments. (See Figure X-17) Ironically,
these investigations have been carried
out primarily to determine the sources
of oil in sediments, not the fate of oil
in the sea.
Emery summarized much of this
work in 1960 in his book The Sea
Off Southern California. He found
the greatest rate of accumulation of
hydrocarbons in marine sediments to
be in certain stagnant basins, where
they could amount to as much as
0.15 percent of the dry weight of sedi-
ment. Emery's calculations showed
that about 880 tons of such material
were deposited annually in the sedi-
ments over an area of 78,000 square
kilometers, compared to an annual
production of 135,000 tons of similar
materials by the phytoplankton over
the same area. Disregarded entirely
in this computation is the possibility
that any of the hydrocarbon mal
currently being deposited in the sedi-
ments is reworked from the numer-
ous seeps in this region of the Cali-
fornia coast.
Recent work by Horn, Teal, and
Backus of Woods Hole Oceanographic
Institution not only shows that float-
ing lumps of petroleum residue are
common on the sea surface but sug-
gests two methods by which the con-
stituents of such lumps can be trans-
ferred to the sea floor through natural
processes as well as a natural method
for disposing of the material at the
sea surface.
Natural Sinking Processes —
Goose-neck barnacles, which at cer-
tain seasons of the year attach them-
selves to any suitable firm substrate
near the sea surface, were found
adhering to floating lumps of petro-
leum. Since these creatures secrete a
calcareous exoskeleton, they are sig-
nificantly heavier than sea water;
Figure X-17 — PETROLEUM HYDROCARBON CONTAMINATION
IN THE MARINE ENVIRONMENT
SEDIMENTS
Location ppm
West Falmouth, Mass., USA ._._ - ..up to 12,400
(dry wt.)
West Falmouth, Mass., USA 21-3,000
(wet wt.)
Narragansett Bay, Rhode Island, USA - - 50-3,560
(dry wt.)
Chedabucto Bay, Canada _~ 0-6.8
(dry wt.)
The table shows some measurements of petroleum hydrocarbons found in sediments
of coastal waters. Studies have shown that marine organisms are adversely affected
by petroleum and that complex mixtures of petroleum hydrocarbons are present
both in sediments and marine organisms. It is estimated that the input to U.S.
coastal waters of petroleum hydrocarbon via sewage effluents ranges from 12,000
to 150,000 metric tons per year.
361
PART X — ENVIRONMENTAL CONTAMINANTS
thus, as they grow they unquestion-
ably transfer lumps of petroleum
residue to the sea floor by adding
weight. It is in all probability this
effect and not slight toxicity that
accounts for the observation that the
largest barnacles attached to oil lumps
were 8 millimeters long, whereas bar-
nacles attached to pumice reached 11
millimeters.
The existence of floating pumice
itself suggests another possibility in
the transfer of floating oil to the sea
bottom. Floating pieces of pumice on
the sea surface are observed to de-
crease continually in size as the result
of abrasion through wave action. The
abraded particles in turn conceivably
can be accumulated by (or accumu-
late) petroleum particles to the extent
that the mixture is heavier than sea
water and hence sinks to the bottom.
Surface Removal Through Bacterial
Action — The mechanism for removal
at the surface is bacterial oxidation.
Horn and his colleagues found oxy-
gen consumption of a floating oil lump
at 10 centigrade to be about the
equivalent of oxidation of 7 x 10 °
g/hr"Vcm"L' of petroleum. Since a
sphere has a surface: volume relation-
ship of 3/r, this observation tells us
that floating oil with a density of 1.0,
if divided into spherical particles of
radius 21 x 10 ,; cm, will be com-
pletely consumed in one hour at 10°
centigrade. One can reasonably ex-
pect this value to increase to 42 x 10"°
cm at about 18° and to double again
at about 26 centigrade. By the same
arithmetic, a film of oil 7 x 10"'' centi-
meters thick will be consumed in an
hour if the bacteria thrive only on
one surface at 10° centigrade, but in
half this time if they can attack both
surfaces at once.
It may be more illuminating to
consider these rates in terms of years
(8,765 hours). At 10° centigrade, a
layer of oil attacked on only one sur-
face will be consumed at the rate of
0.6 millimeters per year. This figure
may be compared with Emery's 880
tons per 78,000 square kilometers in
a year, which is about 1.1 to 10"''
millimeters per year, or his 135,000
tons per year of petroleum-like sub-
stances produced by phytoplankton,
which is 1.7 to 10"'' millimeters.
These rate computations allow us
to draw several conclusions. One is
that the practice of adding emulsi-
fiers to floating oil to facilitate its
dispersal into small units will also
facilitate its natural oxidation as long
as the emulsifiers are not bactericidal.
Another is that keeping the oil at the
sea surface, where ambient tempera-
tures are highest, will minimize the
time required for its natural oxida-
tion. And another is that oil will be
more persistent in polar latitudes than
in temperate or tropical latitudes.
Still another is that both "natural"
accumulations of petroleum compo-
nents in marine sediments and pro-
duction of similar compounds by
phytoplankton take place at rates
much below the "natural" ability of
the systems at the sea surface to
oxidize floating oil residues.
Inasmuch as bacteria form an im-
portant food source for the ciliary and
mucus feeders in the marine plank-
ton, then, and since observation
shows that bacterial growth is en-
hanced in the presence of the combi-
nation of solid surface and source of
fixed carbon offered by floating oil
lumps, it seems inconsistent to refer to
their presence as "chronic pollution."
Additional Sinking Agents — In
shallow coastal water, supposing that
oil is delivered to the sea surface at
a rate greater than that at which it
can be naturally oxidized, it seems
likely that airborne dust and other
solid residues will act as additional
agents in increasing the density of
floating oil and causing it to sink to
the bottom. A layer of tarry residue
will then exist on the bottom in such
localities, its thickness increasing with
time at a rate equal to the rate of
delivery of oil minus the rate of oxi-
dation in situ. Such layers can indeed
be observed on the bottoms of indus-
trial harbors.
Needed Scientific Activity
Although present knowledge tells
us that, at least in some cases, no
harmful effects can be attributed to
the presence of petroleum on the
sea — the sea off southern California,
for all its dozens of oil seeps, is one
of the more productive fishery areas
in the world — it would be a mistake
to assume that we already have all
the information required to settle the
question of whether oil on the sea
floor is preferable to oil at the sea
surface. For one thing, crude petro-
leum varies widely in its chemical
makeup. We need, therefore, to ex-
amine the relative toxicity of crudes
from a variety of sources to marine
plants and animals, pelagic and ben-
thic. We need also to examine the
rate of bacterial oxidation of various
crudes and to establish the effect of
temperature on these rates.
We need also to study bottom con-
ditions in the vicinity of oil terminals
and tidewater oil refineries as com-
pared with control areas lacking such
industrial activity to determine the
extent to which areas of the ocean
floor have already undergone the type
of modification that has been ob-
served in New York's East River —
where there is a thick layer of "black-
top" in the vicinity of the Brooklyn
Navy Yard — and the influence that
incorporation of petroleum residues
into bottom sediments has had on the
benthic biota. And we need to map
the various areas of the continental
shelves and slopes of the world, down
to the depth below which bottom
conditions are without influence on
fisheries, and to evaluate their pro-
ductivity in terms of current fishing
operations.
At depths greater than about 750
meters, the sinking method of oil dis-
persal can presumably be used with-
out fear of harmful effects. Over
lesser depths, where important de-
mersal fisheries exist, only laboratory
studies of the effect of sunken oil
on the biota can provide pollution-
362
MARIN] NANTS
control authorities with the informa-
tion that will enable them to evalu-
ate whether removal of floating oil
through causing it to sink to the
bottom is economically preferable to
attempting to collect it on the surface,
to speed its natural removal by
spreading emulsifying agents, or let-
ting it drift ashore.
The observation of Horn, Teal, and
Backus that barnacles thrive attached
to floating petroleum lumps and that
a pelagic isopod preferentially asso-
ciates itself with the same items sug-
gests that the components of such
lumps are not toxic to these groups
of Crustacea. It is generally supposed
that the lower-molecular-weight con-
stituents of petroleum are more toxic
than those of higher molecular weight.
It is also true that the vapor pressure
and solubility in water of these con-
stituents both decrease markedly with
increasing molecular weight. It seems
likely, therefore, that natural proc-
esses in the ocean may act rather
rapidly in the case of floating petro-
leum residues to leave only the more
inert, heavier fractions at the sea
surface, the lighter fractions having
been either volatilized to the atmos-
phere or dissolved in the mixed layer
of the ocean above the thermocline.
Some direct observations of the
change in composition with time of
floating oil spill seem highly desirable
in this regard.
Horn and his colleague;: further
suggest that toxic petroleum co
nents find their way into the food
chain through fish like the saury,
which appear to be voracious feeders
of anything they may encounter at
the sea surface. It would appear to
be relatively easy to sample saury
from the catches of the wide-ranging
Japanese fishing industry, as well
as apex predators such as dolphin
(Coryphaena), swordfish, and tuna,
to determine if, in fact, any accu-
mulation of undesirable compounds
originating in petroleum can be de-
tected. Porpoises, also mentioned by
Horn, can be readily sampled through
the individuals that are captured acci-
dentally in tuna-seining operations.
363
PART X — ENVIRONMENTAL CONTAMINANTS
5. ENVIRONMENTAL DISEASE
Malaria
Malaria in humans continues to be
a major problem in many parts of
the world. Uncritical enthusiasm gen-
erated in the period immediately after
World War II, occasioned by the un-
expected appearance on the scene of
the chlorinated hydrocarbons, led to
the belief that global eradication of
malaria was a possibility. National
and international agencies invested
large sums of money in sweeping pro-
grams, built upon the observations
that the residual effects of long-
persisting insecticides, when these
had been applied to the walls of
dwellings, would serve to interrupt
the transmission of malaria by cut-
ting short the lives of the vector
anophelines, thus denying to the para-
site the chance to infect new hosts.
There were early victories in re-
gions where the habits of the specific
vector species led, in a certain few
instances, to actual eradication of the
vector or, in other instances, to inter-
ruption of transmission and eradica-
tion of malaria. In still other instances
victory was partial, and marked re-
duction in incidence of malaria could
he noted. (See Figure X-18) In other
instances, notably in Africa, parts of
Asia, and parts of South America,
results have been disappointing.
In the large-scale campaigns, em-
phasis was placed almost entirely on
control procedures and the intricate
logistic problems relating thereto. For
a period of two decades, there was a
decided slump in the volume of basic
malaria work carried on; fundamental
studies on parasite biology, host-
parasite interactions, drug prophylaxis
and therapeusis, and the biology of the
anopheline vectors were neglected.
The recognition that resistance to
insecticides was emerging in anophe-
line vectors (not as serious a problem
Figure X-18 — CHANGES IN MALARIA MORBIDITY
BEFORE AND AFTER MOSQUITO CONTROL
Area
Year
Number of Cases
Mauritius
Cuba
Dominica
1948
1969
1962
1969
1950
1969
46,395
17*
3,519
3
1,825
Nil
Dominican Republic
1950
1968
17,310
21
Grenada and Carriacou
1951
1969
3,233
Nil
Jamaica
1954
1969
4,417
Nil
Trinidad and Tobago
1950
1969
5,098
5
Venezuela
1943
1958
817,115
800
India
1935
1969
more than 1,000,000
286,962
Bulgaria
1946
1969
114,631
10*
Italy
1945
1968
411,602
37
Romania
1948
1969
338,198
4*
Spain
1950
1969
19,644
28*
Turkey
1950
1969
1,188,969
2,173
Yugoslavia
1937
1969
169,545
15*
China (Taiwan)
1945
1969
more than 1,000,000
9
imported or induced cases.
The table shows the effectiveness of selected mosquito-control programs, most of
which use DDT. Over 1,000 million people have been freed from the risk of malaria
through such programs.
364
ENVIRONMENTAL DISEASE
yet as that seen in Aedes aegypti)
provided signals that difficulties could
be anticipated in the application of
standardized control procedures in
regions where earlier work had been
successful. Furthermore, malaria para-
sites have emerged markedly resistant
to the commonly used antimalarials.
This has spurred the search for new
antimalarial agents and has indicated
the need for extension of more basic
parasitologic studies.
The problem of drug resistance is
particularly acute in Southeast Asia.
The U.S. Army Research and Devel-
opment Command has established a
broadly based program of research,
largely monitored through the Walter
Reed Army Institute for Research,
with the collaboration of the U.S.
Armed Forces Epidemiological Board
and the U.S. Public Health Service.
Research efforts have also been inten-
sified in a number of other countries.
The State of Scientific Knowledge
Further discussion requires subdi-
vision into a series of topics, often
intricately interassociated.
Malarial Parasites — Earlier beliefs
that malaria was exclusively limited
to humans have been modified, since
it has been shown that P '.falciparum,
P.vivax, and P.malariae can all be
passaged to subhuman primates, can
establish infections, and that anophe-
lines can be infected from such
sources and can transmit further to
primates. The owl monkey (Aotus
trivirgatus) of South America has
been particularly useful in these
studies, though, unfortunately, it is
not readily obtained in large num-
bers. Passage of the parasite in such
hosts provides material for detailed
studies of the host-parasite relation-
ship, and is of great value in provid-
ing quantities of the parasite for
in vitro cultivation and laboratory-
controlled studies on parasite metabo-
lism, enzyme studies, morphological
studies, preparations of antigens, and
the like. The importance of extra-
human cycles for maintenance of the
parasites in nature is of obvious in-
terest in epidemiology, and awaits
critical assessment.
Detailed morphological studies
have provided new insights into the
anatomy of the parasite. They prom-
ise to provide powerful tools for
direct observation of the mechanism
of action of antimalarial agents on
the parasites. Such studies, coupled
with studies of the enzyme systems
involved in drug action, should point
the way to rational development of
antimalarial drugs. These studies are
intimately related to studies on the
basic structure and biology of the red
blood cell.
There has been a considerable ex-
tension of knowledge relating to the
exo-erythrocytic cycle of develop-
ment of malaria parasites in the ver-
tebrate host. This is a particularly
important field, since it relates to
problems of malaria prophylaxis and
to the radical cure of the established
infection. Failures in prophylaxis and
therapeusis of the non-drug-resistant
parasites may be due to failure of the
drug to get to the parasite, or the
parasite form itself may be less sensi-
tive. The former is the likeliest
hypothesis.
The recognition in recent years that
strains of P '.falciparum are markedly
resistant to 4-aminoquinolines and to
widely used antimalarials has pro-
duced a spurt of new research. Proj-
ects involve the coordinated efforts of
synthetic chemists, biochemists, phar-
macologists, clinicians seeing drug-
resistant cases (particularly in troops),
and clinical-laboratory groups study-
ing the new drugs and combinations
of drugs under controlled conditions.
Several different drug combinations
are being used to treat drug-resistant
cases; in addition to chloroquine, they
employ certain sulfones and certain
anti-folic acid agents such as amodia-
quine and related compounds. The
immediate problem, control of the in-
fection in the individual, has in large
part been met, but there is much
unresolved in studies of comparative
efficacy and in evaluation of the pos-
sibility that the parasite will develop
resistance to a further range of anti-
malarial drugs.
Intensive search for new antima-
larials — not just relatives of known
antimalarials — has involved the elab-
oration of drug-screening procedures
of several types: rodent malaria sys-
tems; avian malaria systems; systems
monitoring the development of para-
sites in mosquitoes or mosquito or-
gans, human malaria parasites, using
in vitro systems, and, ultimately, ma-
laria parasites of humans in humans.
Promising leads include phenan-
threnes and naphthoquinones, but
they are few in relation to the total
effort. The "one shot" antimalarial
is still a dream.
Human Host — A prominent ques-
tion remains unsolved: What fac-
tor(s) cause febrile paroxysm? Newly
developed techniques for fractiona-
tion of parasites and for fractionation
of infected red blood cells may lead
to a resolution of this question.
The sickle-cell trait in humans has
been well established as exerting a
protective effect in P. falciparum, in-
fections. A similar situation has been
postulated for the G-6-PD deficiency
state, but supporting evidence is not
convincing. Further combined field
and laboratory studies are indicated.
The possible relationship of ma-
laria to Burkett's lymphome has been
advanced on epidemiological grounds;
this possibility is currently being
studied intensively in East Africa.
The problem of hemolysis in
G-6-PD deficient subjects treated with
8-aminoquinolines has been promi-
nent in troops in Southeast Asia,
and the subject of detailed studies.
Other drug-treatment problems have
been recognized, particularly the de-
velopment of irreversible scotomata
following prolonged chloroquine
therapy, and agranulocytosis follow-
ing diaminodiphenyl-sulfane therapy.
365
PART X — ENVIRONMENTAL CONTAMINANTS
These latter reactions, although so far
few in number, often terminate in
death. It is suspected that they may
be related to decomposition products
in aged stores of the drug.
Diagnosis — The classical proce-
dure of diagnosing malaria on the
basis of finding the parasite remains
unchallenged. The paucity of tech-
nicians able to apply the established
procedures accurately reflects the lack
of interest in most medical schools
and training centers in tropical medi-
cine in general and malaria in par-
ticular.
Direct immunofluorescence using
tagged immunoglobulins to signal the
malaria parasites in blood smears is a
workable procedure, but it is not ex-
tensively used, and not likely to be.
Indirect immunofluorescent proce-
dures utilizing prepared malaria
smears, sera being examined for pres-
ence of antibody, and tagged anti-
globulins to the host serum have
shown much promise, particularly in
permitting study of the immune status
of populations. It is not probable,
however, that such techniques will
find application in the diagnosis of
the immediate malarial illness in a
human.
Further refinements are to be an-
ticipated, involving the application of
newer techniques to obtain purified,
or separated, parasite and serum frac-
tions. Practical application of such
methodology by routine diagnostic
laboratories will come slowly, if ever.
Vectors — The maintenance of ma-
laria in the human community is a
reflection of vector-host-parasite in-
teraction, as well as environmental
factors. (See Figure X-19) The vector
must have an association with hu-
mans, and the parasite must be avail-
able. This relationship is highly com-
plex put nonetheless subject to analy-
sis by construction of models which
can be adapted to computer analysis.
Macdonald's contributions to such a
model are well known.
It becomes apparent that many or
most of the variables introduced into
the equation are ill defined, and that
many of these relate to the mosquito
vectors. A single model can only ap-
ply to a single vector, and there are
several dozen well-recognized vectors.
For each vector, field information is
necessary relating to distribution,
densities, longevity, flight range, feed-
ing habits vis-a vis humans as con-
trasted to other blood or food sources,
resting habits, frequency of refeeding,
susceptibility to insecticides, and sus-
ceptibility to the malaria parasite in
question. As such questions are ex-
plored, there is frequently need for
more specific taxonomic detail, and
certain of the earlier recognized vec-
tors, such as Anopheles gambiae,
have been split into a series of recog-
nizable entities (races? species?) with
distinctly different biology.
Control — This topic must be con-
sidered with respect to the several ac-
cessible components: the parasite, the
host, and the vector.
The finding of drug-resistant para-
sites complicates greatly the already
complex problem of control through
direct attack on the parasite through
mass chemotherapy of human popu-
lations. Drug-resistant parasites have
thus far not been recognized in Africa.
Should they be transplanted there
through migrations of parasitemic hu-
mans, or through development locally,
the result would be disastrous.
The host can be approached through
immunization procedures. Recent
work in rodent malaria systems on
developing immunogens derived from
sporozoites is encouraging enough to
merit extension of such studies to hu-
mans. Other approaches to the host,
apart from such obvious measures as
use of protective clothing, bed nets,
and insect repellents — all of limited
effectiveness unless conscientiously
employed — have centered largely on
the insect-repellent aspect. An ap-
proach through development of sys-
tematic insecticides or repellents,
which have had some success in pro-
Figure X-19 — AREAS OF MAJOR MALARIA POTENTIAL
Malaria mosquitos cannot survive in areas where temperatures fall below 15° centi-
grade and annual rainfall is less than 1,000 millimeters. By combining the 15°
centigrade isotherm (broken line) and the 1,000-millimeter isohytel (solid line),
one can determine the areas where mosquito survival is continuous (shaded sec-
tions), with consequent heavy risk of malaria, and the areas (hatched sections)
where unusually heavy rainfall can permit mosquitos to survive and malaria to
spread.
366
ENVIRONMENTAL DISEASE
tecting livestock, does not hold much
promise for human use. More effec-
tive repellents are being sought, but
prospects for compounds appreciably
more effective than those now used
are dim.
Vector-control programs through
the application of residual insecticides
have had distinct success; there have
also been failures. In part, the failures
have resulted from development of
resistance to insecticides; but in
greater part failures have been due to
biological behavior patterns of the
anopheline species in question, pre-
cluding effective exposure to residual
insecticides. Larviciding techniques,
particularly including low-volume
aerial application of insecticides, are
in a phase of reassessment.
New techniques of vector control,
using genetic manipulation, insect
pathogens, antimetabolites, and insect
hormones are currently attracting
much attention. Genetic manipulation
includes male sterility induced by ir-
radiation of chemosterilants, cytoplas-
mic incompatibility, and translocation
semisterility. Successful application of
such techniques will require much
more comprehensive knowledge of
the biology of each anopheline species
under consideration than now exists.
In this connection, the biology of the
nonbiting males of the many species
has received little attention in the
past but may well be critical in at-
tempts at genetic manipulation of
populations.
A related approach involves at-
tempts to replace a vector population
of one species by a nonvector popu-
lation of a different species through
competitive displacement. Such an ex-
periment is now under way on a Pa-
cific atoll, attempting to displace the
filaria vector species. The concept
could also be applicable to displacing
a parasite-receptive clone of a vector
species by a parasite-resistant clone of
the same species.
Epidemiology — Studies relating to
the central problem — the under-
standing of the epidemiology of ma-
laria in human populations — are
indicated at various points in the pre-
ceding discussion. It must be further
pointed out that epidemiological
studies today are greatly embarrassed
by the various types of partial control
which may be operating in a field lo-
cality, including partially effective
drug therapy with many drugs, chang-
ing agricultural and living habits of
populations, and partially effective
vector-control programs. In the proc-
ess of measuring, variables change
and the picture changes. This situa-
tion cannot be controlled and will not
change.
Need for Trained Manpower
Especially important is continuing
training of field epidemiologists, with
enough background to permit them to
work effectively on actual field prob-
lems of malaria in overseas locations.
This should include medical person-
nel, entomologists, and control ex-
perts. Most of the medical schools in
the United States and in the world do
not meet this problem adequately, and
attention should be given to the
strengthening of several centers that
can be recognized as training centers
for tropical diseases in general and
malaria in particular.
Other Parasitic Diseases
Many parasitic infections are, in
fact, zoonoses with significant inter-
relation between man and domestic or
wild animals — e.g., hydatid disease,
American trypanosomiasis, leishmani-
asis, and fascioliasis. Study and con-
trol of such parasitic diseases are
seriously neglected though they cause
immense losses — both social and
economic.
These are diseases of the poor and
ignorant, which can, in part, explain
the neglect since those people have
little political leverage. Nevertheless,
the fund of information on the dis-
eases and their control has run ahead
of the development of sound and use-
ful control programs. Most existing
control programs are weak and inade-
quate despite the gravity of the prob-
lems. Somehow this pattern of neglect
has to be broken.
Schistosomiasis
Schistosomiasis is a worldwide
scourge in regions containing about
592 million people. (See Figure X-20)
About 125 million people are infected.
About 2.6 million are totally disabled
by it and 24.8 million are partially dis-
abled. In Brazil alone, approximately
15.5 million people live in affected re-
gions and 5.8 million are infected;
116,600 are totally disabled and 1.4
million are partially disabled. The
estimated economic loss to Brazil due
to the "loss of resources" (i.e., loss
due to reduced productivity of goods
and services alone) is estimated to be
about $106 million per annum.
The disease is out of control in al-
most all endemic areas and has spread
or increased in prevalence in Africa,
the Philippines, and Brazil in recent
years. In these areas, the increase has
been due to migration of infected peo-
ple, opening up of new areas for
settlement, or water resources devel-
opment schemes.
Schistosomiasis demonstrates par-
ticularly well the complex feedback
among human health, agriculture, in-
367
PART X — ENVIRONMENTAL CONTAMINANTS
Figure X-20 — WORLD DISTRIBUTION OF SCHISTOSOMIASIS
The maps show the distribution of various forms of schistosomiasis. The disease
is a major block to agricultural progress in many of the world's developing nations.
368
ENVIRONMENTAL DISEASE
dustry, social structure, social change,
and economic development. The dis-
ease affects mainly the poorer people
closest to the soil. Low economic
status promotes the disease because it
forces people to live in unsanitary
conditions. Ignorance is also a major
factor in lack of sanitation. The dis-
ease causes significant illness and de-
bility in a large proportion of the
infected population. These people
compete less well and are less produc-
tive. The disease, then, holds them
down. Farmers, because of the nature
of their work, are more often exposed
to the infection. Urbanization reduces
the danger of spread of the disease,
but water resources development
schemes — with their dams, irrigation
systems, and water-level-stabilization
activities — promote the transmission
of the disease. Water resources devel-
opment schemes that can produce
significant economic and social ad-
vancement can be severely weakened
by the spread of this disease that can
result directly from the changes the
schemes require.
Current Scientific Knowledge — We
know enough to control schistosomi-
asis in most of the endemic zones.
The way to do it is by reducing snail
populations and contact of man with
"infected" water. New molluscicides
offer a reasonably economical oppor-
tunity to reduce transmission drastic-
ally. New drugs are in development
that offer for the first time a hope for
easy treatment with reduced toxicity.
There is no reasonable prospect of a
vaccine or other means for control
of the disease except, perhaps, for
use of competitor snails in some
localities.
Needed Activity — The technical
base is thus reasonably good. Of
course, more information would help.
Safer drugs, easier snail control, and
a way to vaccinate against the disease
can be hoped for. Recently, there has
been a series of efforts to produce
mathematical models for analysis of
transmission problems and for predic-
tion. They are in the exploratory
phase and are not really predictive yet.
Figure X-21 is one input to such a
model.
But control schemes will need more
trained people, support, and — per-
haps hardest to get — good national
organizations devoted to the problem.
We have spent enough time "finding
out" what we need to know about the
problem. We need to get on with con-
trol schemes and continue to learn
as we go along. A strong push could
work wonders in control of the dis-
ease in a number of countries.
Chagas' Disease
(American Trypanosomiasis)
Chagas' disease occurs in almost all
American countries and exists in re-
gions inhabited by about 35 to 40
million people. At least 7 million are
usually considered to be infected,
though the number is sometimes esti-
mated to be as high as 10 million. In
some endemic zones, 50 percent or
more of the people are infected; of
these, 10 to 20 percent have signifi-
cant cardiac damage or intestinal-tract
damage due to the infection. Morbid-
ity and mortality data are not very
good. One careful study of the causes
of death that occurred in Ribeirao
Preto, Brazil, over a two-year period
showed that the disease was the cause
of 29 percent (40 out of 139) of the
male mortality in the 25 to 44 year
age group — a shocking figure. Ar-
gentina considers that it has 2 million
infected citizens and 400,000 with
heart damage or other significant con-
sequences of the infection. Venezuela
has about 2.8 million people exposed
to the infection in the endemic zones
and about 560,000 infected persons,
of whom about half have significant
cardiac damage as a result.
Chagas' disease is a disease of the
poor, ignorant, and badly housed. It
is primarily rural, though some cities
are heavily affected in the poorer
parts. Poverty and lacl
tion results in constrm bad
houses of poor materials and in poor
maintenance of houses. Such houses
are excellent harborages for the insect
vectors. The disease produces, in a
proportion of its victims, acute illness
followed by delayed cardiac or diges-
tive-tract damage. These can termi-
nate in heart failure, invalidism, and
loss of productivity. The disease
strikes particularly hard among young
adults in their most productive years
and when their families are most
vulnerable to economic stress. The
circle of poverty-ignorance-sickness-
economic failure is a difficult one to
break.
Venezuela is the only country with
a control program of a size and sig-
nificance commensurate with the size
of the problem. A few other countries
have limited control programs (partic-
ularly Chile, Brazil, and Argentina).
Many countries do not know the mag-
nitude of their problem with any ac-
curacy at all though in many of them
there is undoubted widespread mor-
bidity due to the disease.
Current Scientific Knowledge —
Knowledge of the disease is now ade-
quate for effective control. What is
needed is the decision that control is
worth the cost and that it must be
undertaken. Systematic use of insec-
ticide (benzene hexachloride or diel-
drin) can cut the transmission rate
to a low level. Spraying costs $5 to
$10 per house and may have to be
repeated every two to three years.
This is relatively costly, considering
the political and economic status of
the people affected and considering
the inability of most of the countries
to spend large sums on disease control.
In a number of countries, it is nec-
essary to determine the importance of
the problem. This can be done by
systematic sampling to determine
prevalence of infection (serological
test) and prevalence of significant
morbidity (electrocardiogram). Both
are technically feasible in any country.
369
PART X — ENVIRONMENTAL CONTAMINANTS
Figure X-21 — EJECTION OF SMALL DROPLETS INTO THE
ATMOSPHERE BY BURSTING BUBBLES
THIS SEQUENCE OF PHOTO-
GRAPHS SHOWS THE COL-
LAPSE OF A 1.7 mm DIAME-
TER BUBBLE AND THE FOR-
MATION OF A JET.
THE TIM.E INTERVAL BE- _
TWEEN FRAMES 1 AND 4 £
IS ABOUT 2.3 MILLISECONDS.
OBLIQUE VIEW OF THE JET
FROM A t mm DIAMETER
BUBBLE
C=^T
r # BACTERIA/,
r ^
.: '. i -.- yj-. . . j i . — •**.v.*.V
• w.v ■/••• • : *.* :* * • •.-. v.v * : • .'
■.-;©■■ '•
CONCENTRATION OF BACTERIA IN JE"
DROPS FROM BURSTING BUBBLES
The diagram shows how disease-laden water vapor can enter the atmosphere.
When a droplet of water such as rain falls out of the atmosphere through a surface
of water, its shape changes and shortly triggers a jetlet, which is then ejected up-
ward from the water surface. A droplet of water from the jetlet remains in the
atmosphere, while the rest of it collapses. A similar situation occurs when bubbles
formed beneath the water surface, as by decomposition, rise to the surface and
burst. If, in either of these cases, the water surface is contaminated, then con-
taminated droplets enter the atmosphere and may be transported great distances.
It is thought that hoof-and-mouth disease spreads in this manner.
Needed Activity — Priorities for re-
search include:
1. Improved and more economical
diagnosis; a simpler serological
test.
2. Expanded exploration of possi-
bilities for a vaccine.
3. A breakthrough on measures
for vector control, particularly
since the insecticides now relied
on may have to be discouraged
because of their cumulative tox-
icity in the environment. (One
household may require several
kilograms of 5-percent benzene
hexachloride for each spraying,
and some houses have been
sprayed several times. The rate
of application is 0.5 gram of the
active insecticide per square
meter of surface inside and out.
Latin America has enough well-
qualified people in the subject. Those
in research need financial help. If they
are in national control programs, they
need advice and support. Most coun-
tries need to be pushed into more ag-
gressive control efforts. The immuno-
logical studies can be supported both
in and out of the endemic zones. In-
ternationally supported control cam-
paigns to improve, not replace, houses
and to spray houses could have a
dramatic impact on the disease.
370
PART XI
HUMAN ADAPTATION TO
ENVIRONMENTAL STRESS
GENETIC ADAPTATION TO THE ENVIRONMENT
An evaluation of man's adaptation
to the environment depends, obvi-
ously, on the use of the two key
words, adaptation and environment.
To begin with the latter, its use in
connection with adaptation usually
brings to mind the physical environ-
ment — climate, etc. — but the bio-
logical environment of a species, in
the form of disease or predators, is
also well known. Furthermore, many
of the important problems of man's
adaptation are now concerned with
the psychological or social environ-
ment. People are as much a part of
the environment as sunlight and rain-
fall, and the problems of man's in-
traspecific aggression and population
control must take into account adap-
tations to this environment.
If the definition of environment is
extremely general, even nebulous, the
definition and uses of the concept of
adaptation are even more so. In fact,
there is considerable confusion as to
the nature of man's "adaptations"
because of the very loose use of the
term. General systems theory, for
which adaptation is a central concept,
can be applied to everything from
physical systems or phenomena to
cultural change. Even within the bi-
ological sciences there are many uses
of the term adaptation. However, the
most general use is to define genetic
adaptations, which are changes in
the gene frequency of a population
in response to or as a result of differ-
ences in the fitness of the genotypes.
Adaptation will here be used only in
this restricted, genetic sense.
Darwinism Revived
As an explanation of human ge-
netic differences, the concept of adap-
tation — or, what is synonymous,
natural selection — has only assumed
its rightful place in the past twenty
years — even though it was Darwin's
major contribution to biological sci-
ence. For almost 100 years after
Darwin, biologists and anthropolo-
gists concentrated on constructing
taxonomies and phylogenies, which
were based on the similarities and
differences among populations of or-
ganisms and were based, implicitly
and explicitly, on the assumption
that these similarities and differences
were "non-adaptive."
In anthropology, the switch to
adaptive explanations began about
1950, with Coon and others, and was
concerned with the visible, measur-
able features of individuals that are
commonly called racial traits. At
about the same time, there was new
work and rediscovery of old work
on the association of the ABO blood
groups and various diseases. The
rediscovery of the work done in the
1920's was comparable in a way to
the rediscovery of Mendel, in that its
significance was now recognized.
This recognition was due to the re-
discovery of natural selection as a
major factor in the evolution of
human differences.
Again in the early 1950's, research
showed that sickle cell anemia and
thalassemia varied in frequency in
different "races"; they occurred with
extremely high frequencies in some
populations. Since these diseases
were known to be due to homo-
zygosity for a single gene (the situa-
tion is somewhat more complicated
now) and were extremely severe if
not lethal, their prevalence raised
some knotty problems for population
geneticists. With such selection
against these genes, there had to be
some other force balancing this ad-
verse selection and thereby causing
the high frequencies. Although there
is still some disagreement — mostly
as to details — it is generally accepted
that heterozygotes for the sickle-cell
gene have a resistance to falciparum
malaria; thus, adaptation, or natural
selection, is the major explanation
for differences among human popu-
lations in the frequency of the sickle-
cell gene. This exampli
that it is used in just about
textbook.
Science, like the rest of human
endeavor, evolves by a pendulum
process. Thus, when these three
trends re-introduced adaptation into
the study of human genetic variation,
adaptive explanations began to be
proposed for most genetic differences.
The result was an exaggeration of
the concept that was almost as faulty
as its total absence had been in
previous work. In the sickle-cell
example, the racial and polymorphic
traits that were explained by adapta-
tion required this concept; they were
obviously genetic differences, and
other explanations seemed inadequate
due to problems such as the extreme
selection against the sickle-cell gene.
After the pendulum swung, explana-
tions by adaptation were extended to
all genetic differences and to many
behavioral differences between popu-
lations. These extensions raise two
questions: (a) how many genetic dif-
ferences are explained primarily by
selection, and (b) how many of the
functional or behavioral differences
between populations are primarily
genetic and due to different adapta-
tions?
Selection as an Explanation for
Genetic Difference
The first question is now being
hotly debated by geneticists. The
debate began with Muller's discus-
sion of "our land of mutations" and
was continued with his paper in as-
sociation with Morton and Crow.
One could almost label this "the
American position," which considers
most genetic loci, or the allelic vari-
ability at most loci, as due to a
balance between mutation from the
normal allele and selection against
the abnormal variants. The state-
ment that most loci are generally
described in this way is reasonable;
373
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
but Morton and others have gone
beyond this position to say that most
selection, and particularly that in-
creased by inbreeding, is associated
with this type of locus and acts to
reduce genetic variation. The other
position is that many loci are balanced
polymorphisms in which the selection
against the two homozygotes balance
each other and result in genetic vari-
ability; the sickle-cell locus (/? hemo-
globin chain) is the most obvious
example.
Both sides agree that both kinds
of loci exist. The questions are how
many of each and how important
for human genetic disease are the
two kinds. Recent estimates of the
number of polymorphic loci — in
other words, loci with at least two
different alleles with appreciate fre-
quencies in a significant number of
human populations — have ranged
around 30 to 35 percent of all human
loci. Thus, while the majority of loci
may well be mutational, problems
and arguments must still be resolved
in order to explain the 35 percent that
are polymorphic.
How much of this polymorphism
is due to adaptation or natural selec-
tion, and how much is simply "neu-
tral" variation? This is one of the
major concerns at present. Again,
the Americans (and the Japanese, fol-
lowing Kimura) are working on the
assumption that most of this varia-
tion is "non-adaptive," while the
British are more skeptical. The ar-
gument seems to go back to the
famous encounters between Fisher
and Wright on the significance of
random genetic drift. In addition,
the assumption of "non-adaptive"
differences among human populations
is basic to the reconstruction of
phylogenies or taxonomies; recent
work on the adaptive significance of
racial differences thus tends to cast
doubt on previous work on race.
However, the opposite position —
that all polymorphic differences are
adaptive — also rests on thin ground.
For example, in European populations
the frequencies of cystic fibrosis ap-
proach those which would be labeled
polymorphic; in Eastern European
Jewish populations the frequency of
Tay-Sachs disease does, too. For
these two loci there has been con-
siderable speculation on the adaptive
significance of the abnormal allele,
although one need not assume selec-
tion for the abnormal allele in these
cases. Much work has also been
done on blood-group systems other
than ABO in an attempt to demon-
strate the action of natural selection.
Selection against heterozygote Rh
babies due to maternal-fetal incom-
patibility obviously exists, but the
attempts to show selection in relation
to environmental factors have not
been very successful. Thus, the posi-
tion that almost all genetic differences
among human populations are due
to adaptive selection cannot be said
to have been proven; on the other
hand, to assume that any locus is
"non-adaptive" because we cannot
demonstrate the selection that may
be involved is also tenuous.
How much selection would be nec-
essary to develop the human genetic
differences we observe? To a great
extent, the answer appears to be
"infinitesimal" — or certainly within
the range of error of the measure-
ments on modern human populations
by which we are trying to detect
selection. This is due to the uncer-
tainties of sampling and the limited
size of the most significant human
populations presently under study,
such as the Yanomama Indians of
Brazil and Venezuela (see Figure
XI-1), who are among the few re-
maining hunters and primitive horti-
culturalists. And yet we know that
human populations do change. De-
spite their seemingly small genetic
differences (see Figure XI-2), Yano-
mama and Japanese are clearly very
different human types. Given this di-
lemma, we are likely to decide be-
tween competing theoretical positions
on the basis of their ability to explain
the totality of human genetic varia-
tion as it exists today and not on the
basis of hoping that we will ever
be able to measure the amount of
selection that existed 10,000 or 20,000
years ago. And our explanations will
contain both instances where genetic
drift, or the "founder effect," were
far more important factors of gene-
frequency change than selection and
vice versa.
Adaptation to Explain Behavioral
Differences
So much for the increased effect
of our knowledge of adaptation on
known genetic differences. We now
turn to the other extension of the
concept of adaptation. To recapitu-
late, adaptation was revived as an
explanation of human genetic differ-
ences because there were certain dif-
ferences among human populations
that could not be explained without
it. Adaptation was then extended to
most other widespread genetic dif-
ferences; it was also extended by
anthropologists, physiologists, psy-
chologists, sociologists, and even edu-
cators to other biological or beha-
vioral differences among groups. If
a group could be shown to be geneti-
cally different in one trait, it was
assumed to be different in many
other traits and, in addition, any
differences that were found among
such groups were implicitly assumed
to be genetic.
The resurgence of Darwinian think-
ing has been pronounced in behavi-
oral studies. These include a great
number of studies of physiological
responses to environmental stresses
such as temperature as well as studies
of the intellectual functioning of the
organisms, which usually fall under
the heading of behavioral genetics.
There is an important difference be-
tween these studies and earlier ones
concerning human differences that
required adaptive explanations. The
latter involved known structural dif-
ferences that could be related to gene
action. For example, the differences
in skin color among human popula-
tions are very pronounced, are known
to be genetic, and, although some
investigators do not think it is
374
GENETIC ADAPTATIONS TO THE ENVIRONMENT
Figure XI — 1 —DISTRIBUTION OF THE YANOMAMA INDIANS IN SOUTH AMERICA
proven, require some adaptiv:
ferences in the skin-color genotypes
in various environments to explain
them. The physiological basis of
this selection has not been demon-
strated, but there is still no other
reasonable explanation in genetic
theory for these differences. The
fact that skin color seemed to be a
climatic adaptation may have given
rise to the idea that there must be
many more climatic adaptations in
man. At first it was hypothesized
that gross structural differences may
exist; but studies have shown that
the number of eccrine sweat glands
as well as the number of melanocytes
are about the same, and their dis-
tribution on the body is also the same
in all groups of men.
The small map shows the general location of the Yanomama Indians. The large
map shows the detailed location of their villages. Two villages located near the
Venezuelan-Brazilian border are those from which blood samples for the cytogenetic
studies were obtained.
Although human structures and
basic responses to climatic stresses
are about the same everywhere, many
physiological studies have shown dif-
Figure XI-2 — CYTOGENETIC FINDINGS IN 49 YANOMAMA INDIANS FROM TWO VILLAGES IN VENEZUELA
In Jungle
Japanese
Males
Females
Totals
Controls
Controls
Number of Cases
32
17
49
2
174
Number of Cells Examined
3175
1700
4875
250
16,035
Per Cent Cells with 46 Chromosomes
96.7
97.1
96.8
97.0
95.6
Number of Cells with One or More
Abberrations:
Total
139 (4.38%)
61 (3.59%)
200 (4.10%)
5 (2.00%)
157 (1.0%)
Single chromatid breaks
80 (2.52)
32 (1.88)
112 (2.30)
4 (1.60)
105 (0.65)
Isochromatid breaks
20 (0.63)
13 (0.76)
33 (0.68)
1 (0.40)
23 (0.14)
Free fragments
13 (0.41)
6 (0.35)
19 (0.39)
0 (0.00)
10 (0.06)
Dicentrics
3 (0.09)
1 (0.06)
4 (0.08)
0 (0.00)
1 (0.006)
Rings
1 (0.03)
0 (0.00)
1 (0.02)
0 (0.00)
0 (0.0)
Translocations, inversions
0 (0.00)
0 (0.00)
0 (0.00)
0 (0.00)
8 (0.05)
Chromatid exchanges
3 (0.09)
4 (0.24)
7 (0.14)
0 (0.00)
5 (0.03)
Centromere breaks
2 (0.06)
2 (0.12)
4 (0.08)
0 (0.00)
5 (0.03)
No. of Complex Cells
17 (0.54)
4 (0.24)
21 (0.43)
0 (0.00)
0 (0.0)
The table shows cytogenetic differences between some Yanomama Indians and
several control populations. The data are compatible, since the same culture
methods were used except that the Japanese control cultures were not delayed in
the initiation of the 72-hour cultures. Complex cells include those with multiple,
exchange-type aberrations.
375
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
ferences. Australian aborigines lose
heat to permit a lower temperature in
their extremities; Eskimos quickly
warm their fingers in an ice bath;
Africans sometimes sweat less in re-
sponse to heat. All of this is blithely
called adaptation, with the presump-
tion that it has a genetic basis. This
work is comparable in method, theory,
and genetic bias to the studies of psy-
chological differences, many of which
have involved "IQ" tests that purport
to tind racial differences in intelli-
gence. The logic of such studies is
that genetic adaptations to environ-
mental differences must exist, and the
only problem is to discover them.
The result of these extensions of
the concept of genetic adaptation has
been to take a well-defined concept
and make it a hodgepodge for any-
one to use. To an extent, this is char-
acteristic of areas of science that are
developing rapidly or are in fer-
ment — and behavioral and physio-
logical genetics are certainly doing
that. The major confusion results
from the use of structural differ-
ences— i.e., genes — to describe func-
tional or behavioral differences, with-
out recognition that vast differences
in behavior are the result of the
environment or of other kinds of
"adaptation" to the environment.
Perhaps we are back to the old
nature-nurture controversy, but there
has been some progress. Great strides
have been made in the analysis of
behavior by the methods of quantita-
tive genetics, and these methods can
be applied to physiological differences
to some extent. But the measure
of genetic determination — heritabil-
ity — applies only to the population
studied and to the differences among
the individuals within it. Within any
population, as well as between popu-
lations, individuals vary in response
to any biological and psychological
test. William has continually stressed
the uniqueness of the individual for
just about anything biological that
one can measure. And it is true that
tests of biological relatives indicate
that some of this variation is due to
heredity. But it is a totally different
problem to explain differences be-
tween populations. It seems reason-
able to most people that these dif-
ferences must also have about the
same genetic component; but that is
not the case.
We are only just beginning to
realize how powerful environmental
influences are in affecting the total
functioning of the individual. "Adap-
tation" — whether to temperature
change, to disease, to crowded con-
ditions, to learning school work —
results from spending one's lifetime
in a particular environment; putting
two different groups in the same
cold chamber, school, or hospital for
a day, a week, or even a year is not
a "controlled" experiment that will
prove genetic or racial differences.
For example, it was long thought that
"natives" had a natural resistance
to some diseases and whites to others
such as TB. However, we are now
seeing that resistance is a function of
previous exposure, amount of ex-
posure, and age at exposure; sim-
plistic notions of racial immunities
are not very realistic.
One cannot say, however, that sig-
nificant differences do not exist or
that there are no genetic factors in-
volved. American Negro troops in
Korea did suffer four times as much
from frostbite as whites; this is a
problem that needs explaining. Amer-
ican and West African Negroes do
seem to have an almost total resist-
ance to vivax malaria, which also
seems to be genetic. Many of the
populations in Europe and Africa
that depend on milk for subsistence
have an active lactase enzyme (among
adults), while most of the rest of
the world's populations are lactase
deficient. Nevertheless, most of the
behavioral differences among popu-
lations that have been called adapta-
tions do not require or demonstrate
genetic differences; rather, they have
been proposed on the basis of tenuous
data and a misunderstanding of the
populational significance of adapta-
tions.
Applicability of Animal Ethology
There is one other area of research
in which the concept of adaptation
has played an important role. This
is the application of animal ethology
to human characteristics. Lorenz on
aggression, Ardrey on territoriality,
Morris on sexual behavior, and others
on all other kinds of behavioral traits
have attempted to develop adaptive,
or "Darwinian," explanations for
these traits. Ethology in its methods
and theories is quite comparable to
behavioral genetics, although the lat-
ter concentrates on human data while
the former generalizes to man on the
basis of analogy with animals.
To show that man is comparable
to the other animals in many ways
is commendable, but it is still impos-
sible to explain the variation in hu-
man behavior among populations by
biological or genetic factors. Aggres-
sion is not universal among human
populations; and it is the variability
in this characteristic that is the an-
thropologist's problem. To disregard
this variability — as does Morris, for
example, by saying that the rest of
the world's cultures are evolutionary
backwaters — is simply fatuous.
As any other species, however,
man does have some species-specific
characteristics; and these are un-
doubtedly due to a long period of
adaptation to a common ecological
niche, which in his case was hunting
with tools on the savannahs of the
Old World. But again, to explain
what is "wrong" with human socie-
ties today by genetic lag is not ade-
quate. If it were, then all human
societies should have these aggressive
genes stemming from our carnivorous
past. But not all societies are as
aggressive as ours. Most ethology-
oriented scientists seem to view man's
cultural evolution as simply social
change which adjusts culture to man's
biological "needs." This view tends
to detract from the power of the
environment to change human char-
acteristics — if one can view cultural
pressure as the environment. It also
376
GENETIC ADAPTATIONS TO THE i
tends to overemphasize the signifi-
cance of genetic adaptation for the
survival of populations.
Adaptation and the Future
of Human Society
Because fitness expresses the ability
of individuals to survive — as well as
to reproduce — fitness differences
among individuals or genotypic dif-
ferences among papulations are usu-
ally assumed to have considerable ef-
fect on the population's survival in the
course of evolution. However, geno-
typic evolution has minimal effect
on a population's ability to survive.
The huge variation in mortality and
fertility rates among human popula-
tion has practically no relationship to
genetic variation. Darwinism seems
to have given rise to such statements
as "the polar bear survives in the
arctic because it is adapted to that
environment"; but in terms of the
course of evolution, the opposite is
true — that is, the polar bear is
adapted to the arctic because it has
survived there. Again, Coon has
stated that Negroes survived in ma-
larial environments because they had
the sickle-cell gene. But why do
several African populations have high
frequencies of this gene? Because
they have survived for centuries in
a malarial environment. (See Figure
XI-3) If, with a simple model for
this sickle-cell locus, one compares
the average fitness of a population
with a high frequency of the sickle-
cell gene to that of one with no sickle-
cell genes, the difference is at most
5 percent per generation. In terms
of a difference in mortality rate, this
is about 2 per 1,000 per year — which
is insignificant when compared to the
vast differences in African mortality
rates that are due to cultural differ-
ences.
Genotypic evolution is the result
of competition between individuals
within a population and has little
effect on population competition.
Similarly, genes have little effect on
other aspects of culture. Cultures
can make any kind of martyr, from
kamikaze pilot to celibate, any time
one is needed; genetic differences in
behavior traits are thus not the major,
or even a minor, cause of cultural
evolution. Even within a population
it is usually considered that such
traits as dominance are genetically
determined; but recent research is
pointing to the opposite view: that
the greater size, intelligence, aggres-
sion, etc., of dominants is the result
of being dominant and not vice versa.
This is only more evidence that
"adaptations" that are almost auto-
matically assumed to be genetic may
actually be environmental.
In summary, there have been
siderable advances in our knowlec
of genetic adaptation where the ac-
tual genes are known, although its
effect vis-a-vis the other determinants
of genetic change is being debated.
On the other hand, the extension of
the concept of genetic adaptation to
other human characteristics is still
much in limbo. This review has been
mostly critical of such work — not
because it is valueless but because
of its very significance for our knowl-
edge of human society. Already,
some are saying that genetic in-
Figure XI-3 — FREQUENCY OF SICKLE-CELL GENE IN LIBERIA
>.ioo
.075-.100
§ .050-.075
Kff^j .025-.050
I 1 .005-.025
The map shows the percentage frequency of occurrence of the sickle-cell gene in
the Liberian population. The malaria parasite has been endemic throughout most
of Liberia, but the sickle-cell gene varies greatly among tribal populations. The
latter variation may be due to the length of time that different Liberian populations
have been exposed to malaria. P. falciparum, the malaria parasite is spread by
the mosquito Anopheles gambiae, which cannot breed in heavily shaded rain
forests. Thus, it— and malaria — were able to advance where rain forest was
destoyed to provide land for agriculture. Slash-and-burn practices began in
northern Liberia and gradually spread southward. Today, the gradation of the
sickle-cell gene follows this same pattern, thus illustrating on a microscale how
the evolutionary process operates. The highest frequency of the sickle-cell gene
exists where the rain forest has been opened up for the longest time.
377
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRES5
equality is somehow incompatible
with "all men are created equal," or
that the division of labor is based
on "natural inequalities." Thus, the
political doctrines of our society are
considered to be based on unsound
biological assumptions. On the other
side, there seems to be resistance to
the idea that any racial characteristic
is adaptive; this is the result of ex-
tending the concept of genetic fitness
to an ideal of individual worth. In
any case, the entire controversy is,
or ought to be, irrelevant to the
ideology or aims of our society.
ASPECTS OF MAN'S ADAPTATION IN THE TROPICS
From our vantage point in the
temperate zones, we look upon man
in the tropics as having undergone
extensive adaptations. In fact, how-
ever, man probably arose in tropical
zones, living in small bands in the
rain forest; from the standpoint of
evolutionary biology, it is we of the
highly civilized countries who are
now making adaptations to a rapidly
changing world.
In recent years, some groups of
investigators have undertaken exten-
sive, multidisciplinary studies of the
surviving groups of primitive man,
these almost without exception in
tropical or subtropical zones. In the
broadest sense, it is the purpose of
these studies to define the popula-
tion structure of primitive man, and
to appreciate the various pressures
(disease, nutritional, etc.) which, in-
teracting with that structure, pro-
vided the milieu within which human
evolution has occurred. It seems ap-
propriate to point out that, in many
respects, ours is the first generation
of scientists to have the facilities for
studies of much deeper significance
than those of the past, and the last
generation to have the opportunity,
since relatively undisturbed primitive
man is rapidly disappearing from the
face of the earth.
With respect to this matter of un-
derstanding better the population
structure of primitive man in the
tropics, the geneticist is concerned
with such matters as: the amount of
inbreeding; the extent of polygyny;
birth rates; neonatal, infant, and
child death rates; marriage patterns,
etc. These factors define the stric-
tures that are placed on the evolu-
tionary process.
Genetic Differentiation
The studies of most groups of
investigators agree in suggesting that
early man in the tropics was charac-
terized by high levels of inbreeding.
They suggest that infertility was un-
common and the reproductive per-
formance of woman relatively uni-
form. On the other hand, because
of the institution of polygyny, male
reproductive performance was some-
what more variable than in the United
States today. The health of the chil-
dren appears to have been better
than those of most peasant popu-
lations.
Studies of the frequency of a vari-
ety of genetic markers in the isolated
villages that comprise most tribal
populations reveal a marked degree
of genetic microdifferentiation — i.e.,
there are rather large genetic dif-
ferences between the villages that
compose a tribe. These villages are
engaged in a constantly shifting pat-
tern of hostilities, one with the other;
that is, competition between demes is
a varied risk. This population struc-
ture is one that population geneticists
feel is particularly conducive to rapid
evolution.
Health Patterns
With respect to the matter of inter-
action with agents of disease, mem-
bers of these tropical populations
have unusually high levels of gamma-
globulin. Because of transplacental
transfer, a child thus comes into the
world with considerable resistance to
local pathogens, conferred on it by
its mother. As the child comes into
active contact with the many disease
agents in its surroundings, it will to
some extent be protected by pla-
centally transmitted maternal anti-
bodies, so that it may have an oppor-
tunity to build up its own resistance
more slowly.
The commitment of many of these
primitive groups to regulation of pop-
ulation numbers is noteworthy. By
a variety of means — intercourse ta-
boos following the birth of a child,
prolonged lactation, abortion, and in-
fanticide — the entry of new life into
the population is rather rigidly con-
trolled. Under these circumstances,
an infant may be nursed for as long
as three years; in general, the nutri-
tion of children is quite excellent.
In this respect, many civilized com-
munities may have lost an adaptation
well recognized by primitive man.
Goiter — With respect to specific
diseases, a number of examples may
be cited as to how markedly many
of these people differ in their physio-
logical adaptations from ourselves,
and how rapidly these adaptations
are altered by acculturation. An out-
standing example is with respect to
iodine. Some of the least-touched
groups of South America live in
areas where iodine is in very short
supply, and yet they do not show
goiter. On the other hand, endemic
goiter is a prominent feature of civ-
ilized populations living under con-
ditions of short iodine supply. Studies
indicate that at least one primitive
group in South America (the Yano-
378
ASPECTS OF MAN'S ADAPTATION IN THE TROPICS
mama) has very high uptake levels
of radioactive iodine, levels that, in
civilized areas, are characteristic of
people with quite large goiters. It
begins to appear that the development
of goiter in the so-called endemic-
areas involves more than simple io-
dine shortage, that there is some
environmental factor which interferes
with the utilization of iodine but
which can be offset by the use of
doses of iodine.
Diabetes — A second example is
provided by diabetes mellitus. In
some of the Indian groups of south-
western United States, diabetes is
appearing with a great frequency
and many complications. Although
the evidence is scanty, the disease
does not seem to be particularly
prevalent among unacculturated In-
dians. The most obvious difference
between Indian groups with high
rates of diabetes and those with low
rates is the greater amount of obesity
and the lesser amount of exercise of
the former. Thus, diabetes mellitus
may represent a breakdown in adap-
tation to a changing way of life.
Caries — For a third and final ex-
ample of how the adaptations of
primitive man in the tropics are
altered by acculturation, one might
mention the well-known example of
caries. Most relatively untouched
groups of primitives are almost
caries-free. But within a few years
of acculturation, caries often become
rampant. The reason is still not
clear. Understanding of any of these
three phenomena would contribute
greatly to our knowledge of man's
adaptation in the tropics as well as in
other regions.
There is a widespread feeling that,
given today's rapid changes in man's
way of life, the selective forces that
shaped him and brought him thus far
are rapidly being altered. Studies
such as the ones briefly sketched here
can provide concrete insight into
the way these forces are being altered.
Many of the conclusions will have to
be inferential rather than demon-
strated. Even so, it is hoped that
such studies will provide a perspec-
tive on the extent of the changes now
occurring in man's way of life and
some of its problems and conse-
quences.
ADAPTATION TO HIGH ALTITUDE
In the autumn of 1967, two inter-
national conferences were held to
assess the state of knowledge about
high-altitude effects on man. One of
these was sponsored by the U.S.
Army Medical Research and Devel-
opment Command, the other by the
World Health Organization (WHO),
the Pan American Health Organiza-
tion (PAHO), and the U.S. Interna-
tional Biological Program (IBP). Be-
tween the two conferences, all major
laboratories and research groups
working in this problem area were
represented. Results were reported
of a decade of intensified research
effort in the United States and abroad.
Information Level as of 1967
The basic physiological and psy-
chological effects of altitude on low-
landers moving rapidly to high
altitudes had been described and
verified by the late 1950's. In the
early 1960's, research proceeded
along these lines:
1. Intensified physiological re-
search on the consequences of
moving men rapidly from low
to high altitude.
2. Study of the physiology and
general biology of high-altitude
natives in Peru, Nepal, and the
United States.
3. Investigation of medical prob-
lems peculiar to men living at
high altitude.
The details of the findings avail-
able from these pre-1968 studies are
too lengthy to cite in a short report,
but some of the highlights were:
1. A detailed description of the
physiological and psychological
limits of low-altitude man's al-
titude tolerance. This included
a partial knowledge of how
much improvement could be
expected in performance ca-
pability with time and some
knowledge about the utility of
drugs in modifying altitude
tolerance.
2. The study of high-altitude na-
tives demonstrated them to be
different from lowlanders in a
number of general biological
and specific physiological pa-
rameters. These differences in-
cluded an increased incidence
of neonatal deaths, different
growth patterns, an oxygen-
consumption capacity above
that of the lowlanders going to
altitude even for an extended
time (see Figure XI-4), and, fi-
nally, a number of unusual dis-
ease characteristics including a
remarkable lack of adult cardio-
vascular disease.
3. The study of medical problems
at altitude had provided a basic
physiological description of the
two direct altitude-related dis-
eases. These are an acute form
producing high-altitude pul-
monary edema (HAPE) and a
chronic form which causes a
runaway polycythemia. Anes-
thesiological and surgical proce-
dures suitable to high altitude
had been partially developed
and it had been discovered that
many drugs have altered action
379
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
Figure XI-4 — CHANGES IN OXYGEN CONSUMPTION CAPACITY OF
LOWLANDERS UPON UPWARD MIGRATION
Population
Number
Sex and
Average
Age
MaxVO. (I/M
STPD
in/Kg)
%
Decrease
Low Altitude
High Altitude
U.S. White
Researchers
12
Male 27
50.4 (300 m.)
38.1 (4000 m.)
24.4
English
Mountain
Climbers
4
Male 32
50.0 (sea level)
39.7 (4000 m.)
20.6
U.S.White
Soldiers
24
Male?
40.4 (sea level)
32.1 (4300 m.)
20.5
Peruvian
Sailors
10
Male 18-21
39.0 (450 m.)
31.4 (4500 m.)
19.5
U.S. White
6
Male 20
64.2 (300 m.)
46.6 (4000 m.)
27.2
Runners
U.S. White
5
Male 15-17
65.2 (300 m.)
49.4 (3100 m.)
25.1
Runners
Peruvian
Quechua
(High Altitude
Heritage)
10
Male 22
49.3 (100 m.)
44.5 (4000 m.)
9.7
The table shows the maximum oxygen consumption capacity of people who nor-
mally inhabit lowlands (below 1,000 meters) and then the percentage decrease
in their ability to consume oxygen upon moving above 3,000 meters. The decreases
are striking except in the last category, those who were children of people
acclimated to high altitudes. Decrease in oxygen consumption is reflected as
a significant loss in work capacity.
on men living in the low oxygen
pressures found at altitude.
The formal publication of results
on man's adaptational problems at
altitude has been substantial since the
beginning of 1968, although since
that time few new major research
efforts have been launched.
Significance of High-Altitude
Research on Man
The relevance of high-altitude re-
search to the 25 million people living
above 8,000 feet is obvious because
of the multiple health effects. The
same is true for those who travel up
and down from these altitudes. Less
can be said about the problem for
the much larger number of people
living between 5,000 and S,000 feet,
since the effects are more subtle and
less well known.
Of perhaps much greater impor-
tance, the study of human popula-
tions living under the drastically re-
duced oxygen pressures found at high
terrestrial altitudes can provide data
of major importance for both such
basic scientific problems as the mech-
anisms of human evolution and such
applied problems as the causes of
cardiovascular disease. For this rea-
son, scientists from practically every
discipline involved in the study of
man have been concerned with high-
altitude research. While it may,
therefore, be suggested that research
on man at altitude is needed because
it may help us discover cures for
adult cardiovascular disease or im-
prove the health of a significant seg-
ment of the world's population, the
major scientific justification is the
use of the environmental contrast as
a research tool.
Research Recommendations
At the 1967 WHO-PAHO-IBP
Meeting of Investigators on Popu-
lation Biology of Altitude, a detailed
set of research recommendations was
developed. These needs have not
been met. The following research
therefore remains of priority interest:
Physiological Adaptation and Ac-
climatization to Altitude Introduc-
tion — Several studies have indicated
that there are important differences
in a variety of structural and func-
380
ADAPTATION TO I liTUDE
tional characteristics among people
who can be identified as: (a) high-
landers for many generations; (b)
lowlanders acclimatized to altitude;
(c) new arrivals at altitude; (d) high-
landers acclimatized to sea level; and
(e) lowlanders.
It is not clear what these differences
mean. We do not know, for example,
whether these differences reflect sim-
ple adaptations to a new environment
or are the result of selective adaptive
processes or even, in some instances,
are detrimental to the individual.
For the people who now live at
high altitude, and for those who will
move there, the most important area
of altitude physiology is that which
has to do with natural and acquired
acclimatization. Study of these proc-
esses should direct particular atten-
tion to the functional adaptation of
people of both sexes, of all ages, and
of those living under different work-
ing conditions.
Of lesser importance to human
populations as a whole is the study
of the acute adaptive mechanisms,
which are of concern to the much
smaller groups of people moving be-
tween high and low altitude and for
whom residence at high altitude is
usually brief.
Physiology of Exercise and Work
Capacity at Altitude — A number of
human populations at various levels
of altitude have for many generations
lived and worked while exposed to
low levels of ambient oxygen content,
although they have not necessarily
been exposed to continued tissue
hypoxia. The physical performance
capacity of these populations is not
adequately established.
Studies were suggested on: the
basic work capacity of highlanders;
the maximum oxygen consumption of
altitude populations; the metabolic
response to work in various high-
lander populations (see Figure XI-5);
the effect of age and sex on work
capacity in altitude populations; the
relationship between heart rate and
oxygen consumption in indigenous
highlanders.
Altitude Limits for Acclimatiza-
tion — There is a need to specify
altitude tolerance limits for human
and other animal species. The tem-
poral maintenance of normal func-
tional integrity of organ systems, be-
havioral activity, and physical and
mental performance should be eval-
uated.
Environmental Factors -
are needed to determine the si
cance of environmental factors other
than hypoxia in altitude acclimatiza-
tion such as the climatic conditions
and the socio-economic environment.
Respiration — An important adap-
tation of the resident to altitude,
which is different from the lowlander,
is his pulmonary ventilatory response
to different concentrations of both
Figure XI-5 — OXYGEN CONSUMPTION CAPACITY AMONG
HIGH-ALTITUDE NATIVES
Population
Location and
Altitude
Number
Sex and
Average
Age
Max V0-
(l/Min/Kg)
STP.D.
Quechua
Peasants
Nunoa, Peru
4000 m.
25
Male
25
49.1
University
Students
"White"
Puno, Peru
3800 m.
13
Male
23.5
42.8
University
Students
"Quechua"
Puno, Peru
3800 m.
10
Male
23.8
46.8
Trained
Quechua
Puno, Peru
4000 m.
9
Male
21.1
48.2
Quechua
IViiners
Morococha, Peru
4540 m.
?
Male
7
51.2
Aymara
Natives
Chile
3500-3650 m.
Male
18.0
49.1
Sherpa
Natives
Nepal
3400 m.
6
Male
17.8
51.9
Aymara
Natives
Chile
3500-3650 m.
Male
25.6
45.4
Sherpa
Natives
Nepal
3400 m.
11
Male
24.6
50.4
Aymara
Natives
Chile
3500-3650 m.
Male
34.8
46.3
Sherpa
Natives
Nepal
3400 m.
Male
34.0
47.4
Aymara
Natives
Chile
3500-3650 m.
Male
44.8
44.0
Sherpa
Natives
Nepal
3400 m.
Male
43.6
43.8
The maximum oxygen consumption capacity of native highlanders at high altitudes
is comparable to that of native lowlanders at low altitudes (see Figure XI— 4). Thus,
the work capacity of the two groups is similar in their native habitats, although
lowlanders are at a disadvantage when they migrate to high levels.
381
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
oxygen (Oj) and carbon dioxide
(COj) in the air he breathes. The
native highlander is relatively less
sensitive to low levels of O- in alveo-
lar air than is the lowlander; it is not
clear whether this decrease in sensi-
tivity is an advantage or a disadvan-
tage at altitude.
Analysis of the important adaptive
respiratory process should include
study of: age and sex differences,
neurological factors, acid-base fac-
tors, chemoreceptor sensitivity and
thresholds, as well as tissue responses
to hypoxia. In addition, it would be
of importance fo study regulation of
ventilation during the performance
of physical work at altitude and dur-
ing sleep. Sleep and associated peri-
odic hypoventilization, as well as
performance of hard exercise, in-
crease hypoxic exposure.
Circulatory Mechanisms of Alti-
tude Acclimatization — Although cir-
culatory responses in man at altitude
have received more study than other
physiological responses, we do not
know the criteria upon which we
could advise healthy people whether
they should or should not live at high
altitude, or at what stage of mor-
phological or functional alterations
they should move to low altitude.
The following areas of investigation
are of importance in answering this
problem:
1. Epidemiology: Much needs to
be known about the prevalence
and incidence of cardiovascular
disease at altitude. Ecological
factors other than altitude
should be identified which af-
fect normal cardiac function in
highlanders. In addition, we
do not know the circulatory
response to physical work at
different ages.
2. Cardiac Muscle Metabolism:
The basic inability of cardiac
muscle to work under anaerobic
conditions makes it vulnerable
to hypoxia induced by high
work loads at altitude. Before
optimal and maximal levels for
work at altitude could be rec-
ommended, further studies are
necessary on coronary blood
flow and cardiac muscle metab-
olism during work and rest at
altitude.
3. Microcirculation: Whether in-
creased capillarity and anasto-
motic vascularity in cardiac or
skeletal muscle is an anatomical
feature of the acclimatization
process needs further study.
The possible role of changes
in the microcirculation in the
development of chronic moun-
tain sickness has not been de-
termined.
4. Pulmonary Hypertension: Lon-
gitudinal observations are
needed in highlanders who de-
velop pulmonary hypertension
and right heart hypertrophy.
Control measurements are
needed that cover both sexes
and a wide age range. Special
study is needed of the factors
that lead to high-altitude pul-
monary edema.
5. Circulation Dynamics: More
information is needed on the
expected changes in cardiac dy-
namics at altitude. Included
under this heading are observa-
tions on cardiac output, car-
diac work, peripheral resistance,
heart rate, stroke volume, blood
pressure as well as the role
of changes in blood volume,
hematocrit levels, and pulmo-
nary circulation. Partitioning
of blood flow through vital
organs under various condi-
tions at altitude is also an im-
portant area to be studied.
Cellular and Tissue Mechanism of
Altitude Acclimatization — The bi-
ochemical mechanisms underlying
high-altitude acclimatization are in-
adequately understood. Respiratory
and vascular adaptations to altitude
that permit an adequate delivery of
O- and removal of metabolites at the
cellular level during rest may not be
adequate for sustained hard work
by healthy men or, for that matter,
sedentary life in the elderly and
infirm. There is a need to determine
the adaptive processes at the cellular
level in the highlander as well as in
newcomers to altitude.
We need to know what role is
played in these cellular responses by
changes in the amount of myoglobin,
the number of mitochondria, and the
capacity of the cytochrome and elec-
tron transporting system. More in-
formation is needed on possible adap-
tive increases in enzymes favoring
both aerobic and anaerobic metabo-
lism. We need to know the degree
to which rate-limiting neurohumoral-
endocrine mediators affect these cel-
lular functions. And finally, we need
to know whether genetic factors are
operative in the adaptation at the
cellular and subcellular level.
Other Areas of Altitude Physiology
Requiring Further Study — Available
knowledge is inadequate concerning
nutritional requirements of those
with natural or acquired acclimatiza-
tion or in those acutely exposed to
altitude. Further nutritional and
metabolic studies are necessary to
establish optimal nutritional allow-
ance for high-altitude residents and
for those who wish to reside at al-
titude.
The factors regulating redistribu-
tion of fluid and electrolytes among
the various fluid compartments need
further elaboration.
In the long-time resident at altitude
we need to know more about the
possible role of adaptive tissue and
vascular responses in the aging proc-
ess. It is also possible that high-
altitude residence has an effect on
man's immunological responses and
on the types and frequency of in-
fections that he harbors.
The sequential changes that occur
during the period of adaptation of
the newcomer to high altitude are
382
ADAPTAT1' [GH ALTITUDE
poorly understood. Accurate time-
tables are not available that show
rate of adjustment for each organ
system including the respiratory,
cardiovascular, digestive, endocrine,
renal, and neuromuscular systems.
The time course of the de-acclimat-
ization process should also be studied,
particularly in those who are exposed
intermittently to altitude.
The working group suggested that
a handbook of physiological values
be developed which uses standardized
terminology. A collection of data
on normal and abnormal biological
values for different altitudes is ur-
gently needed.
Human Biology at High Altitudes
The working group considered the
problems posed by the biology of
human populations living at high al-
titudes, which could also, and equally
importantly, be relevant to many
fundamental problems of human bi-
ology in general.
It seems appropriate to present
the recommendations for these two
approaches separately, although in
practice the methods used and ob-
servations made will be closely sim-
ilar.
The Characterization of High-
Altitude Populations — Using com-
positive methods of approach and
standardized procedures, information
should be obtained in the following
categories:
1. Fertility and the Components
of Fertility: (a) by demographic
methods; (b) by methods used
in the reproductive physiology
of man and of animals, which
could be applied to human pop-
ulation studies.
2. Growth, Development, and Ag-
ing: With a focus on age
changes and variability in char-
acteristics thought to be (a) of
adaptive value at high altitude;
and (b) related to the somatic
fitness of individuals. Such
studies should not be divorced
from the psychological and in-
tellectual changes that occur
during development.
3. Nutrition: In all cases, the
nutritional assessment of the
populations studied should be
made in as detailed a manner
as possible, commensurate with
the resources available. Such
assessments should include: (a)
the nutritional status of indi-
viduals; (b) detailed nutritional
surveys, where possible; and
(c) biochemical studies related
to nutrition.
4. Special Problems Relating to
Work Capacity: Both physio-
logical and psychological meth-
ods should be used.
5. Epidemiology: In all cases, the
pattern of disease distribution
in populations should be stud-
ied. Where additional demo-
graphic information is available,
it is highly important that more
vigorous epidemiological stud-
ies should be made. It is of
great importance that demo-
graphic methods should be de-
veloped which would enable
the relationships between age,
disease, and morbidity to be
ascertained.
6. Genetics: Further information
is required on: (a) the distri-
bution of polymorphic systems
in high-altitude populations;
(b) the heritability of quantita-
tive varying traits, particularly
those presumed to be adaptive
in nature; and (c) congenital
defects, especially those pre-
sumed to have a genetic com-
ponent.
All these studies must include as
precise as possible an analysis of all
biological and physical aspects of the
environment. (See, for e>
ure XI-6) Adequate precautions must
be taken to insure statistical repre-
sentation and control situations,
which will often mean the study of
lowland populations. And finally, the
demographic background of the pop-
ulations under study must be ascer-
tained in as great a detail as possible.
Altitude Studies in General Human
Biology — The ecological situations
of high-altitude populations often af-
ford unique opportunities for the
study of fundamental human biology.
In particular, the following problem
areas can be investigated:
1. Developmental Flexibility: The
determination of the magni-
tude and biological significance
of normal environmentally in-
duced responses.
2. Genetic Structure of Human
Populations: Isolated groups,
where it may be presumed that
factors such as genetic drift
may be operative, are partic-
ularly important objects of
study. Problems involving gene
flow and the effects of selective
migration may also be encom-
passed.
3. Natural Selection: Of the vari-
ety of ways by which the prob-
lem of detecting natural selec-
tion may be approached, it was
thought that particular atten-
tion should be devoted to the
analysis of the comparative fer-
tility and mortality of different
phenotypes and, where pos-
sible, genotypes. Such investi-
gation could be made most
appropriately in both stable
high-altitude populations and
in those which have recently
changed their altitude.
These three topics deal with funda-
mental problems of human biology
and thus conflict with the objectives
of categorizing the biology of high-
altitude population, as discussed
383
PART \I — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
8 -
7 -
6 -
5 -
■1
3 -
2 -
1 -
0 -
7p
6 -
5 -
Figure XI-6 — GROWTH RATE DIFFERENCES BETWEEN
NUNOA AND U.S. CHILDREN
MALES
Nuni-,.1
FEMALES us
..Nunoa
4
\ \,^_
3
-
\
2
-
V
1
0
-
1
1
1
1
1
1 1
'"'•..
.. 1
2
4
6
8
10
12 14
16
18
20
2
2
Age (years)
The graph shows differences in rates of general body growth between Nunoa
and U.S. children. The Nunoa children are primarily of Indian derivation and live
in an area of about 1.600 square kilometers whose minimum altitude is 4.000
meters and whose maximum altitude is above 5,500 meters. The Nunoa children
have a slower rate of general body growth than is standard in the U.S., but their
growth rate continues over a longer period of time.
earlier. However, their study de-
mands a large-scale multidisciplinary
approach in selected areas, in which
the various characteristics itemized
earlier would still have to be subjects.
Health Aspects of Altitude
Ischemic Heart Disease at High
Altitude — There is evidence that the
incidence of ischemic heart disease
in high-altitude populations is lower
than at sea level. Experimental stud-
ies indicated increased resistance to
myocardial necrosis in altitude-accli-
matized animals. A controlled epi-
demiological study of the incidence
of ischemic heart disease in high-
altitude populations will be carried
out using suitable sea-level controls
and standardized techniques of in-
vestigation. Risk factors for ischemic
heart disease will be evaluated and
correlated with necropsy data. Adap-
tive mechanism of the heart to high
altitude pertinent to acute cardiac
necrosis will be examined in experi-
mental animals. Careful investigative
techniques of population analysis will
be employed and, depending on initial
results, preventive trials may be
initiated.
Development of Prognostic Tests
for Altitude Sickness — It is impor-
tant to be able to identify individuals
who are likely to develop acute or
chronic mountain sickness or high-
altitude pulmonary edema. Simple
laboratory methods for determining
the sensitivity of the carotid body
and respiratory responses to various
stimuli including hypoxia should be
devised. Other screening tests should
be evaluated on sea-level subjects
who will later be exposed to high
altitude.
Epidemiology, Therapy, and Pre-
vention of High-Altitude Pulmonary
Edema — By means of questionnaires
and interviews, the importance of
factors such as reascent, length of
stay at sea level, and slow ascent
upon the occurrence of HAPE will
be assessed. Field trials of prophy-
lactic drugs, using a double-blind
technique, will be carried out, prefer-
ably in troops. In selected patients
during the acute stage the hemody-
namic effect of selected drugs will
be investigated. Ventilation-perfusion
characteristics will be examined se-
quentially in the acute stage and dur-
ing recovery.
Congenital Malformations of the
Newborn at High Altitudes — Pre-
liminary studies have shown that
the incidence of congenital abnor-
malities of the heart and other struc-
tures is increased at high altitude.
Whether this is a genetic abnormality
or due to maternal hypoxia at a criti-
cal stage of fetal development is not
known. Since maternal hypoxia can
be prevented or minimized, studies
at high altitude are indicated. The
causative factors can be evaluated by
employing a standard, highly objec-
tive method of examination in a
prospective study of newborn infants
and schoolchildren at selected levels
of altitude in different countries.
Countries to be included are those
where the appropriate facilities are
available. The administration of ox-
ygen to newborns should be carried
out at high altitude with suitable
controls to determine its late effect
on the incidence of PDA and the
cardiovascular system.
384
ADAPTATION T HIGH ALTITUDE
High-Altitude Medicine — Despite
the fact that over 25 million people
live at high altitudes, no information
regarding their special medical prob-
lems is available. The following sub-
jects need to be treated: (a) high-
altitude diseases such as acute and
chronic mountain sickness and high-
altitude pulmonary edema; (b) mod-
ification by high altitude of diseases
that are common at sea level such
as pneumonia, coronary disease, and
shock; (c) action of drugs such as
opiates and anesthetics that are modi-
fied by high altitude; (d) occupa-
tional diseases at high altitudes. The
emphasis should be on clinical medi-
cine rather than physiology.
Evaluation of the Effects of Pul-
monary and Cardiac Disease upon
Cardio-Respiratory Function at High
Altitude — Pulmonary function and
hemodynamic studies should be car-
ried out in high-altitude residents
with silicosis, stanniosis, and follow-
ing pneumonectomy. The working
capacity of such patients should be
evaluated by appropriate methods.
Techniques of early detection of in-
dustrial pulmonary disease at high
altitude should be evaluated and ap-
plied to workers.
Factors Affecting Biliary Cholelithi-
asis in Native Highlanders — Choles-
terol stones are commonly observed
at high altitude, with probably a
different sex incidence than usually
observed at sea level. Since this is
an important cause of illness, the
causative factors should be studied.
The study should include an inves-
tigation of dietary habits and serum
lipids of patients with proven chole-
lithiasis compared to control subjects
living in the same area with normal
cholecystograms.
Drug Action at Different Alti-
tudes — Drug action is probably sig-
nificantly modified in the hypoxic
high-altitude environment. Toxicity
may be enhanced or diminished and
the therapeutic effect may be altered.
Studies should be made and known
information collected regarding the
effect of selected drugs at various
altitudes in the world. Drug'
as narcotics, anesthetics, analgesics,
opiates, pressor drugs, and cardiac
glycosides should be investigated.
Vital Statistics in Relation to Al-
titude — Vital statistics of WHO are
arranged for countries according to
many categories — but not altitude.
Such information is necessary in
order to determine the effect of al-
titude upon the incidence of disease
and mortality.
Functional and Intellectual Cor-
relates of Altitude Hypoxia in Chil-
dren — It is important to determine
if the development and function of
the central nervous system is ad-
versely affected by the chronic hy-
poxia of high altitude. Suitable
physiologic tests should be developed
to quickly determine the degree of
chronic hypoxia in children. Tests of
central nervous system functions that
could be affected by chronic hypoxia
should be designed that would be
suitable for field studies.
ADAPTATION TO SMOG AND CARBON MONOXIDE
Smog is a vaguely defined word,
certainly not a well-defined chemical
species. In general, it means the
totality of community air pollution,
though it has been applied more
specifically (a) to sulfur oxide and
particulate pollution, occurring chiefly
in coal-burning areas, and (b) to
photochemical air pollution, common
in southern California, which is af-
fecting an increasing number of ur-
ban cities with intense pollution from
motor-vehicle exhaust.
Smog in southern California has
not been shown capable of increasing
the short-term fatality rate, but both
types of community air pollution
cause respiratory irritation, both can
aggravate asthma (though they prob-
ably do not cause it), and both are
suspected of a part in the develop-
ment of chronic respiratory disabil-
ity — emphysema in the case of
photochemical pollution, and chronic
bronchitis in the case of sulfur oxide
and particulate pollution. Readily
measurable impairment in airway
resistance and other respiratory func-
tions occurs among the populations
most likely to show increased fre-
quencies of chronic bronchitis and
emphysema. The distinction between
the two diseases as causes of death
is largely related to the extent to
which there are adaptive mechanisms
in the airways causing increased se-
cretion of mucus.
Man is exposed to carbon mon-
oxide (a) in cigarette smoking, (b)
in occupational exposures to com-
bustion products, (c) in connection
with community air pollution, (d)
in confined areas contaminated by
motor-vehicle exhaust, and (e) when
household cooking and heating ap-
pliances are not adequately vented.
Carbon monoxide can and does kill,
especially in association with occupa-
tional exposure and poorly vented
appliances. There is growing suspi-
cion that the excess mortality from
coronary heart disease among ciga-
rette smokers may be due to carbon
monoxide, a major toxic constituent
of cigarette smoke. (See Figure XI-7)
There is also a suspicion that carbon
monoxide, as a community air pollu-
tant, may interfere with the survival
of patients with acute myocardial in-
farction (heart attacks), and that it
may play a role in impairing the op-
eration of motor vehicles.
385
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
Figure XI-7 — POSSIBLE EPIDEMIOLOGICAL AND PATHOPHYSIOLOGICAL
MECHANISMS RELATING CARBON MONOXIDE
AND MYOCARDIAL INFARCTION
Cigarette Smoking
Domestic
(?Seasonal)"
Ambient Pollution
_. CARBON MONOXIDE .
"* EXPOSURE
-Occupation
■ Emphysema -
->(Pulmonary Diffusion)
I j ^ Carboxyhemoglobin
>0xygen Delivery Rate ♦
Y„ Y2, . . Y„
-> Hematopoesis
Blood Viscosity
Heme Catabolism
'(Hgb, Catalase, etc.)
Carboxymyoglobin
Oxyhemoglobin
Dissociation
Myocardial
Atherosclerosis Metabolism
Cardiac Work
X,, X„ . . X„
Thrombo-embolism
Myocardial Infarction ^_
Fatal Myocardial Infarction
The figure shows, on the right-hand side, possible biochemical and physiological
mechanisms and, on the left-hand side, possible epidemiological associations.
Solid arrows indicate an increase; open arrows, a decrease or impairment of the
mechanism. This scheme is qualitative and some of the reactions shown may be
of insignificant magnitude.
Testable hypotheses relating carbon monoxide and myocardial infarction from a
clinical and mechanistic view are numerous, but testable hypotheses relevant to
the epidemiological approach are few. And yet an investigation of the epidemio-
logical approach would produce observations on biological and physiological
processes as well as studies of disease frequency.
Scientific opinion increasingly tends
to the view that air-pollutant expo-
sures, whether smog or carbon mon-
oxide, do not generally cause a specific
disease, but rather that they contrib-
ute to the aggravation, and possibly
to the causes, of several possible dis-
eases. In an excessively simplistic
way, the main target organ for smog
is the respiratory system. The main
target organ for carbon monoxide is
the circulatory system, with the cen-
tral nervous system being a secondary
target.
The human processes of adapting
to these agents produce alterations in
function and may also be the same
mechanisms that lead to their con-
tributions to chronic disease and dis-
ability. Should this suspicion be
borne out by research over the next
five to ten years, the likelihood of
a substantial reduction in two very
common classes of chronic disease
would be greatly advanced. Since
heart disease accounts for about 20
percent and chronic respiratory dis-
ease for about 2.5 percent of all
deaths in California from 1965
through 1967, even a small diminu-
tion in the burden attributable to
them from adaptive reactions would
be well worthwhile.
Present Scientific Data Base
One major piece of evidence re-
lating the finding of symptoms of
persistent cough and sputum and
impairment of respiratory function
with the likelihood of developing
chronic respiratory disease is a study
by Gregg, a general practitioner, of
patients in a relatively unpolluted
sector of London. Cigarette smokers
in his practice who had persistent
cough and sputum when first ex-
amined had a more rapid deteriora-
tion of pulmonary function during
the ensuing five years and also a
lower initial function than persons
with a similar smoking history but
no symptoms. In the case of carbon
monoxide exposures, the much higher
frequencies of coronary heart disease
among cigarette smokers suggest a re-
lationship between carbon monoxide
exposures and the chronic diseases
associated with lipid deposition in
the main blood vessels. So, too, does
the demonstration by Astrup in Den-
mark that, among persons with well-
advanced atherosclerotic disease who
were smokers, there were much
higher levels of carboxyhemoglobin
than among those with similar smok-
ing histories but who did not have
atherosclerosis.
Recent findings may help to iden-
tify those individuals in a population
who are susceptible to the chronic
diseases associated with maladapta-
tion to inhaled pollutants. These in-
386
ADAPTATION TO 5MOG AND CAR15' s^ MONOXIDE
elude, in particular, the demonstra-
tion that a diminution in trypsin
inhibitor in the serum (the so-called
alphai anti-trypsin deficiency syn-
drome) predisposes individuals who
were homozygotically deficient to the
early onset of pulmonary emphy-
sema. Such individuals are infre-
quent in the population; studies so
far report finding only about one in
3,000. However, it is not yet known
whether /zeferozygotically deficient
individuals (who may comprise 5 to
15 percent of the general population)
are also more prone to chronic res-
piratory irritants. In a few pilot
studies, heterozygotically deficient in-
dividuals who were also cigarette
smokers showed evidence of chronic
respiratory disease in a very high
proportion, namely 31 out of 33.
Needed Scientific Activity — Adap-
tation to carbon monoxide involves,
to a substantial degree, the study of
populations of cigarette smokers,
since their exposures to this agent
are very common and of substantial
magnitude — that is, sufficient to in-
activate from 5 to 15 percent of the
oxygen-carrying capacity of the blood
for moderately heavy smokers who
inhale. Similarly, there is evidence
that cigarette smoking increases the
risk of chronic respiratory conditions
and respiratory impairment in per-
sons exposed both to the sulfur oxide
and particulate type of pollution and
to photochemical smog. (See Figure
XI-8) Thus, we are unable to speak
logically of the epidemiologic aspects
of studying human adaptation to car-
bon monoxide and to smog without
considering cigarette smoking.
Beyond this, however, we must
also consider occupational exposures
and relevant and related exposures
that occur in the home and during
recreation and transportation. While
there are large numbers of human
subjects exposed to both carbon mon-
oxide and smog, a longitudinal study,
necessary to obtain the best type of
data for the study of adaptation,
has rarely been undertaken for either
of them. In the case of occupational
exposure to carbon monoxide, some
longitudinal data have been obtained;
there are, however, few longitudinal
data in the case of carbon monoxide
associated with cigarette smoking,
since the importance of this exposure
has been appreciated only since 1960.
In the case of smog, there are popu-
lations occupationally exposed to two
of the major ingredients that have
toxic properties — namely, ozone and
nitrogen dioxide — but results of the
study of occupational groups are not
sufficiently clear-cut for an evalua-
tion of adaptation.
Short-term adaptive mechanisms
have a more abundant data base.
There is a small data base from ex-
perimental human studies, and a
somewhat larger one from experi-
mental animal studies, of adaptive
mechanisms for ozone and nitrogen
dioxide exposures. Data for carbon
monoxide are more abundant, but for
neither is the data set adequate.
Limitations — The data base for
studying adaptation to these agents
is unfortunately impaired by the
view of one sector of the scientific
community that adaptation is solely a
beneficial process, one that does not
carry with it the risks of the long-
term consequences suggested above.
Thus, a number of scientific papers
have cited the ability of patients to
increase the oxygen transport in re-
sponse to carbon monoxide exposure
as evidence that community or ciga-
rette-smoking exposures to carbon
monoxide are of little consequence to
health.
Recent Scientific Findings
Impairment of Respiratory Func-
tion — It has been demonstrated that
nitrogen dioxide, a major product of
photochemical smog, is an effective
agent for producing emphysema in
experimental animals when exposures
Figure XI-8 — RATES OF CHRONIC BRONCHITIS AND EMPHYSEMA
FOR SMOKERS AND NON-SMOKERS
21 AND OVER
PRESENT SMOKERS BY NUMBER OF
CIGARETTES SMOKED PER DAY
—HEAVIEST AMOUNT
The diagram shows the substantial contribution of cigarette smoking to chronic
respiratory conditions. Heavy smokers have as much as five times the excess
morbidity of non-smokers. For females this excess is even greater than for males.
The rates are adjusted for age and include data on subjects 17 years of age and
over.
387
PART \I — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
are long term and at concentrations
as low as from 0.8 to 4 parts per
million. The work has been reported
by Freeman and his colleagues and
has been demonstrated in rabbits,
rats, mice, and monkeys.
Closely related is the finding of
Mueller, Buell, and Thomas, at the
California State Department of Public
Health, that structural changes in
proteins can be produced by ex-
posures to low levels (0.25 to 5 ppm)
of either nitrogen dioxide or ozone
for a short period of time, and that
these changes revert slowly. The
mast cells reversibly disappear from
the respiratory airways on exposure
to nitrogen dioxide; nitrogen dioxide
and ozone inhalation can lead to
lipid peroxidation in the pulmonary
parenchyma. These changes are all
presumably adaptive in nature, but
their consequences for long-term ef-
fects are certainly suggestive, since
lipid peroxidation has also been as-
sociated with the aging processes.
Balchum, Armstrong, and Ury have
reported the impairment of respira-
tory function in persons already hav-
ing chronic respiratory diseases who
were exposed to elevated levels of
photochemical smog occurring in Los
Angeles. The lung-function test most
consistently responding was that of
airway resistance, and its increase
reflects the likelihood that persons
with chronic respiratory diseases
would have to expend more energy
to ventilate their lungs during smoggy
periods than during normal ones.
Toyama in Japan and Holland,
Douglas, Waller, and Lunn in Eng-
land have shown that schoolchildren
exposed to pollution, mostly in the
forms of sulfur oxide and particu-
lates, have impaired respiratory func-
tion during periods in which the pol-
lution is elevated and have a greater
frequency of respiratory conditions.
The finding, which has been con-
firmed in Italy, should also be studied
in other countries. It seems quite
reasonable to assume that these
changes in schoolchildren represent
adaptation, and with it the risk of
developing chronic respiratory dis-
ease. At a meeting in Geneva in
1969 of the Directors of Cooperating
Laboratories of the World Health
Organization's International Refer-
ence Center on Air Pollution, the
recommendation was adopted that
first priority for additional compara-
tive epidemiologic studies in air pol-
lution should be given to studies of
the effects of air pollution on school-
children.
Impairment of Circulatory Func-
tion — Astrup has shown that the ex-
posure of rabbits on a high-choles-
terol diet to increasing amounts of
carbon monoxide will increase the
atherosclerotic changes in the large
blood vessels. Similar changes can
be produced by placing the animals
in a chamber with low oxygen ten-
sion. The findings that smokers with
atherosclerosis have higher levels of
carboxyhemoglobin, implying higher
or more intense exposures to carbon
monoxide or greater retention from
smoking, than do individuals with
similar smoking histories but without
atherosclerosis, is strongly suggestive
of the role of carbon monoxide in this
process. Yet human populations at
high altitude, where the oxygen ten-
sion is low, have a lower frequency of
atherosclerosis, lower blood pressure,
and lower cholesterol. Accordingly,
it has been most valuable to have an
experimental comparison of the ef-
fects of high altitude and of repeated
carbon monoxide exposures in healthy
experimental subjects reported by
Astrup and Pauli.
They studied eight subjects divided
into two groups of four; each group
was exposed both to sufficient carbon
monoxide to produce 15 percent car-
boxyhemoglobin and to altitude at
11,225 feet (roughly equivalent in
terms of oxygen saturation). The
major findings were that with car-
to.ryhemoglobin exposure, the oxy-
hemoglobin saturation curve shifted
to the left (i.e., the available oxygen
would be given off less readily at the
tissue level under these circum-
stances), whereas with altitude the
curve shifted to the right (i.e., the
hemoglobin would more readily give
up its oxygen at the tissue level).
Carboxyhemoglobin exposures did
not increase the respiratory rate, but
altitude did. Both types of exposure
increased the rapidity with which
new red blood cells were produced.
Both types of exposure, if sufficiently
intense and prolonged, are capable
of leading to an increase in the
hematocrit. Thus, the major differ-
ence in adaptation to altitude and
roughly equivalent carboxyhemoglo-
bin levels produced by exposure to
this agent is that men adapt to
changes in oxygen delivery in the
case of altitude; in the case of carbon
monoxide exposures, the changes
that occur in oxygen delivery appear
to be maladaptive. There is a res-
piratory volume compensation for
decreased oxygen-carrying capacity
in the case of altitude, but there is
none for carbon monoxide.
Ayres, among others, has shown
that different portions of the circula-
tory system have different ways of
adapting to the impairment of oxygen
transport produced by carbon mon-
oxide exposures. (See Figure XI-9)
In particular, the myocardin adapts
to increased demand of the heart
by increasing the blood flow, since
its oxygen-extraction ratio is usually
much higher than other tissues. That
is to say, the heart normally takes
out of the blood that circulates
through it a high fraction of the
available oxygen in relation to the
pattern for other organs. Hence, im-
pairment in oxygen delivery by car-
bon monoxide requires an increase in
the blood flow through the heart
muscle. In the case of people with
coronary heart disease, however,
there is no way in which the heart
can increase its blood flow. Thus,
according to Ayres' data, it is demon-
strable that in persons with coronary
heart disease, carbon monoxide dras-
tically interferes with the metabolism
of the heart muscle, shifting it from
an oxidative to a less efficient form
388
ADAPTATION TO SMOG AND CARBON MONOXIDE
Figure XI-9 — HEMODYNAMIC AND RESPIRATORY RESPONSES OF FIVE
NORMAL SUBJECTS TO CARBOXYHEMOGLOBIN (COH. )
Subj.
COHb
(% sat)
Pressure (mm-Hg)
Ar-ven diff
(% by vol.)
Cardiac
output
(lit./
min)
Vent
(liter)
CO,
(mm-Hg)
LA
(wedge)
PA
(mean)
Arfo2
Ven fo2
1
10.48
1 8.84
28
28
9
9
89
81
45
42
3.40
3.82
5.23
4.46
4.23
4.23
34 1
36 [
2
j 6.29
86
80
37
30
3.96
4.55
4.37
4.35
4.68
5.72
36 1
36 [
3
I
3
3
14
12
74
68
42
37
3.92
4.24
4.31
4.17
2.55
3.11
36)
40 f
4
10.37
| 4.95
9
9
13
13
84
79
49
42
4.00
4.66
5.32
6.54
5.43
7.36
39 1
38 (
5
10.96
| 9.69
7
11
12
18
77
72
41
35
4.02
4.81
6.00
4.68
4.87
4.24
36 1
39 (
The table shows that the oxygen tensions of arterial and mixed-venous bloods
decreased between 7.3 and 13.3 percent, respectively, when the carboxy-
hemoglobin rose to between 4.95 and 9.69 percent of saturation. Cardiac output,
oxygen consumption, and body-surface ventilation per minute did not change
consistently, but the difference in arterial and venous blood, reflecting extraction
of oxygen by tissue increased in all five subjects. In the one patient who received
the greatest amount of carbon monoxide, left arterial pressure rose and cardiac
output fell, indicating abnormal left ventricular function. These studies show that
small amounts of carboxyhemoglobin do indeed decrease oxygen tension in the
blood which in turn may cause other problems related to the supply of blood
throughout the body.
The first line of each set of data shows value before breathing CO at 0.4 percent in
air; the second after breathing. Abbreviations are: sat, saturation; LA, left atrium;
PA, pulmonary artery; AR, arterial; t,, , oxygen tension; Ven, mixed venous; Ar-ven
diff, arterial-venous difference; Vent, ventilation per square meter of body-surface
area per minute; tco , carbon-dioxide tension.
of metabolism. Such individuals can-
not adapt efficiently to carbon mon-
oxide exposures.
r'ermutt and Farhi have worked out
a theoretical example of the compen-
sations needed to maintain tissue
oxygenation in the presence of 9
percent carboxyhemoglobin, which
would correspond to a continuous
exposure of a normal subject at sea
level for several hours to carbon
monoxide (CO) at 70 parts per mil-
lion. Such a CO hemoglobin satura-
tion would have an effect equivalent
to that found with a 23 to 46 percent
decrease in the oxygen pressure
available for supplying the needs of
the body, and a 13 to 37 percent
decrease in blood flow or decrease
in the amount of circulating hemo-
globin. In order to compensate for
this amount of COHb, an increase
of from 19 to 39 percent in blood
flow would be required. This analysis
has forcefully driven home the high
physiologic cost of adapting to car-
bon monoxide.
The Risks of Long-Term Expo-
sures — Long-term exposures of an-
imals, particularly small rodents, have
shown that ozone will increase pul-
monary fibrosis, just as long-term
exposure of other animals will in-
crease pulmonary emphysema. It has
also been shown by Stokinger and
his colleagues that the exposure of
experimental animals to brief, low
levels of ozone protects them from
subsequent high-level exposure which
would otherwise be fatal. This is
doubtless a useful adaptive mech-
anism, but its cost may be to increase
the risk of chronic respiratory dis-
ease. Stokinger and his group have
also shown cross-tolerance between
ozone and other oxidants. However,
tolerance in man has not been dem-
onstrated.
Bennett has reported on long-term
exposures of small numbers of hu-
man subjects to 0.5 parts per million
389
PART XI — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS
of ozone, 3 hours a day, 6 days a
week, for 12 weeks. The individuals
so exposed had a gradual decrease
in the forced expiratory volume in
one second which began to occur
after 8 weeks of exposure and con-
tinued to be depressed for 8 weeks
after the termination of exposure.
A lower dose failed to produce this
effect.
Prevailing Controversy and
Needed Research
Cohen, Deane, and Goldsmith,
utilizing data obtained for other pur-
poses, studied the possible effect of
carbon monoxide exposure on the
case fatality rate among persons ad-
mitted to Los Angeles hospitals with
myocardial infarction. They showed
that the rate increased during the
high pollution period and in the
higher of the two pollution areas of
Los Angeles County. Without addi-
tional studies, however, they were
reluctant to attribute this increase
only to carbon monoxide. Contro-
versy also exists concerning the effect
of carbon monoxide on the central
nervous system and, hence, its pos-
sible role in the performance of com-
plex tasks requiring accurate time
evaluation, such as driving an auto-
mobile. There has been no decisive
evidence concerning the role of car-
bon monoxide in general in motor-
vehicle accident frequency.
The interaction of the various com-
ponents of both forms of smog in
producing health effects remains con-
troversial. Of particular interest is
the hypothesis recently put forward
by Pitts, among others, that one of
the essential mechanisms in the early
oxidation of nitric oxide to nitrogen
dioxide is the absorption of energy
by atmospheric oxygen and conver-
sion of some of the normal triplet
oxygen to a singlet delta form that
may have a finite half-life and could
be of biological importance.
A cross-sectional study of the fre-
quency of emphysema in several cities
in relation to the history of smoking
and of pollution exposure is going
to be necessary in order to resolve
some of the questions about the
effects of smog on chronic respiratory
disease. The identification of active
atmospheric species produced by
photochemical processes is an im-
portant one that may have powerful
interactions with radiological health
and carcinogenesis. Closely related
is the possibility that agents in photo-
chemical smog may be mutagenic or
teratogenic, though such reactions
would scarcely be considered adap-
tive ones.
Relationship to Environmental
Management
It is clear that community exposure
to carbon monoxide would be sub-
stantially diminished if automobiles
in operation were decreased either
in number or in the amount of car-
bon monoxide that they emit. Re-
duction in emissions of hydrocarbons
and oxides of nitrogen should also
have a substantial effect on the in-
tensity of photochemical smog, al-
though the effect will take a number
of years to be fully evident. Since
1956, the United Kingdom has
greatly reduced the amount of par-
ticulate matter in many of its urban
areas, and since 1967 there has been a
pronounced decrease in sulfur oxide
and particulate emissions in coastal
cities of eastern United States. Stud-
ies by Fletcher and his colleagues
have shown that, in parallel with the
decrease in particulate matter in Lon-
don, there has been a decrease in
the frequency of chronic bronchitis
and in the amount of sputum pro-
duced by groups of people who had
comparable smoking exposures all
during this period.
The attention paid to atmospheric
pollutants is responsive largely to
public concern with air pollution as
a menacing and offensive substance.
The public has not felt it necessary
to know the precise health effects.
The possibility exists, therefore, that
some questions that are of great sci-
entific importance will never be an-
swered, since it is hoped that the
increasingly vigorous control meas-
ures advocated by the Environmental
Protection Agency will reduce com-
munity exposures and thus make
some of the longitudinal studies un-
likely to reflect present or increased
exposures.
Thus, the greatest priority should
be given to the specific exploration
of the hypothesis that pollutant ex-
posures which lead to impairment of
function may also increase the risk
of developing chronic cardiac and
respiratory disease through the mech-
anisms of adaptation which they pro-
voke. Longitudinal research on ex-
posed populations and their adaptive
mechanisms has been inadequately
supported because of the difficulty of
assembling teams of competent in-
vestigators over the longer periods of
time necessary for this sort of re-
search. From two to ten research
groups, some of which are not in
the United States, will be needed to
plan and carry out longitudinal
studies to evaluate the adaptation of
human subjects to smog and to car-
bon monoxide.
390
APPENDIX
SUMMARY AND RECOMMENDATIONS
Reprinted from the Third Annual Report of the National Science Board Environmental
Science — Challenge for the Seventies (NSB 71-1).
Modern civilization has reached the stage where, hence-
forth, no new use of technology, no increased demands on the
environment for food, for other natural resources, for areas to
be used for recreation, or for places to store the debris of
civilization, can be undertaken to benefit some groups of indi-
viduals without a high risk of injury to others. No environ-
mental involvement of man can any longer be regarded as all
good or all bad. Problems can be mitigated, but absolute
solutions are probably unattainable. The best that can be
sought, therefore, is to optimize, to try to achieve the wisest
cost-benefit decision for society for each action contemplated.
Such a strategy requires a strong base of scientific knowledge
and understanding of the environment, ability to predict reli-
ably its future course, and, especially, the ability to construct
models through systems analysis of the environment and of
man's interaction with it on a scale never previously achieved.
It is within this perspective that the present status of
Environmental Science has been examined. Environmental
Science is conceived in this report as the study of all of the
systems of air, land, water, energy, and life that surround
man. It includes all science directed to the system-level of
understanding of the environment, drawing especially on such
disciplines as meteorology, geophysics, oceanography, and
ecology, and utilizing to the fullest the knowledge and tech-
niques developed in such fields as physics, chemistry, biology,
mathematics, and engineering. Included, therefore, are such
diverse matters as climate, air turbulence, the air-sea interface,
estuaries, forests, epidemics, earthquakes, and groundwater.
These environmental systems contain the complex processes
that must be mastered in the solution of such human problems
as the maintenance of renewable resources (water, timber,
fish), the conservation of non-renewable resources (fuels,
metals, species), reducing the effects of natural disasters
(earthquakes, tornadoes, floods), alleviating chronic damage
(erosion, drought, subsidence), abating pollution by man
(smoke, pesticides, sewage), and coping with natural pollution
(allergens, volcanic dust, electromagnetic "noise").
Environmental Science is now exceedingly vigorous, con-
sidered in relation to its development over many centuries.
Notable advances are being recorded at an accelerating rate
New tools and techniques, borrowed from all of science and
technology, are being brought to bear on the problems of
observation, measurement, and analysis. Across all of environ-
mental science there is a heightened awareness of the essential
nature of the environment and the directions that scientific
effort should take. Nevertheless — and it is the principal con-
clusion of this report —
Environmental science, today, is unable to match
the needs of society for definitive information, pre-
dictive capability, and the analysis of environ-
mental systems as systems. Because existing data
and current theoretical models are inadequate,
environmental science remains unable in virtually
all areas of application to offer more than qualita-
tive interpretations or suggestions of environmental
change that may occur in response to specific
actions.
There are two primary reasons for this state of affairs.
One involves the nature of environmental science itself, the
other the resources available for its advancement.
(1) The natural environment is not a collection of iso-
lated events and phenomena, but rather a vast, integral,
mutually interacting system. The recent advent of new
technology and technique (satellites, advanced computers,
instrumentation of many types, and the methods of sys-
tems analysis) for the use of environmental science has,
indeed for the first time, provided feasibility for attacking
the scientific problems that this environmental system
presents. The tasks ahead, however, are of unprecedented
magnitude and difficulty.
(2) The trained scientific manpower available to meet
this challenge is extremely limited in each of the essential
aspects of environmental science. More serious is the fact
that this manpower is spread exceedingly thin, both with
respect to the manifold problems presented and to the
institutions within which research is conducted, new sci-
entists are educated, and scientific results are applied to
the solution of problems of the public interest. Indeed,
the institutions of environmental science, as here defined,
remain in an early stage of development.
This situation constitutes a crisis for the Nation. While
environmental problems are so diverse and diffused that virtu-
ally every activity of civilization interacts with the environ-
ment, few persons can be aware of the full scope of challenge
that lies ahead. The current mismatch between capability and
need is at least comparable to any other challenge to science
and technology that was encountered during this century.
To meet this situation the National Science Board offers
five groups of recommendations:
1. NATIONAL PROGRAM
Several factors emphasize the urgency of establishing a
national program for advancing the science of environmental
systems: (a) New organizations formed at the highest level
of the Federal Government, the Council on Environmental
Quality and the Environmental Protection Agency, have been
charged with responsibilities that include the assessment of the
environmental impact of civilized man. These agencies must
foresee secondary effects and compare quantitatively the
multiple consequences of alternative courses of action. Such
efforts are severely limited by the present level of understand-
ing of the behavior of environmental systems. They would
become progressively more feasible as advances in environ-
mental science increase man's predictive power, (b) The use of
energy and the processing of material by man are doubling
391
APPENDIX
every 14 years.* Correspondingly, the number and severity of
environmental problems will increase, while the adequacy of
ad hoc piecemeal expedients will decrease, (c) As population
grows, and with it the artifacts of civilization, the human and
economic losses due to sporadic natural disasters, already great,
will increase in scale, (d) At the same time, the intensification
of man's needs for both renewable and non-renewable re-
sources requires even greater manipulation and mastery of the
natural and man-made systems that constitute the environment.
It is, therefore, recommended that this urgency
be recognized through the early development of
a comprehensive national program to expedite the
progress of environmental science.
The problems with which environmental science must
deal, however, do not respect local, State, or even national
boundaries. It is thus further recommended that this national
program explicitly provide for the essential Federal role in
encouraging and supporting the work of environmental sci-
ence, quite apart from the role the Federal Government is al-
ready exercising with respect to improving and protecting the
environment (e.g., programs of soil conservation, sewage treat-
ment, air and water pollution control, etc.). Both nationally
and in matters of international cooperation the Federal Gov-
ernment must assume leadership in fostering scientific advance.
This national program should be based on three
efforts:
(1) Emphasis should be given to projects,
manned by coordinate teams, directed to inter-
mediate scale or "mesoscale" problems, that is,
problems on the scale of lakes and estuaries,
urban areas, regional weather systems, and oce-
anic fisheries. Advances on this scale will provide
immediate benefits to man.
(2) At the same time, the program must ensure
continued effort on global problems, even though
their solution may require the resolution of smaller
scale issues. In the long run it is the global con-
straints that will shape and delimit the future
development of civilization.
(3) Finally, the program should ensure the con-
tinued vigor of those aspects of disciplinary re-
search and graduate education needed to provide
the specialists and new knowledge required for
environmental science.
The remaining recommendations form an important part
of the total recommendation of a national program. The entire
program should be established at the earliest practicable date,
if progress during this decade and its culmination during the
following decades are to be commensurate with the urgency
now faced.
2. PRIORITIES
One of the inescapable conclusions of this report is that
the number and complexity of scientific problems, both theo-
'Both activities have shown 5% average annual growth rates for the last 20
years, as reported in Man's Impact on the Global Environment: Assessment and
Recommendations tor Action, MIT Press, Cambridge, Mass., 1970. The total
consumption of fossil fuel in the United States also grows about 5% per year;
the conversion of an increasing fraction of fossil energy to electrical energy
leads to a higher annual growth rate in the utilities.
retical and experimental, that confront environmental science
far exceed the capability of available manpower to attack all
of them effectively at the same time. If these resources remain
distributed as they are, scattered and fragmented, and if prob-
lems to be solved are selected largely on the basis of the per-
ceptions of individuals or small isolated groups, progress in
environmental science cannot meet the needs of expressed
national goals and purposes.
Accordingly, it is recommended that early con-
sideration be given to strengthening arrangements
whereby priorities for environmental science can
be set, matched to existing and required scientific
and engineering manpower, and changed as cir-
cumstances warrant. In setting such priorities ap-
propriate weight must be given to the feasibility of
achieving scientific solutions in a reasonable time
and to the social and economic costs and benefits
that could accrue if solutions were attained.
3. ORGANIZATION FOR ENVIRONMENTAL SCIENCE
The scope encompassed by the national program, proposed
above, the Federal role inherent in this broad effort, and the
patent need for establishing priorities raise serious questions
of the adequacy of present arrangements within the Federal
Government for planning, coordinating, managing, and re-
viewing programs of environmental science. As for all science,
environmental science today is the responsibility of many
agencies, often with conflicting interest under differing agency
missions and responsive to many Congressional committees.
At the same time the problems to be solved are broader, more
difficult, and more dependent upon the coordinated use of
scientific resources than those faced in the earlier development
of nuclear energy, radar, and space exploration.
For these reasons, it is strongly urged that the
Federal responsibility for environmental science,
and for its promotion, organization, and support,
be considered as important as the corresponding
but separate responsibility for environmental qual-
ity. In particular, arrangements for Federal deci-
sionmaking must be especially effective for the
following activities:
(1) The setting of priorities affecting all research
and development in environmental science sup-
ported by the Federal Government.
(2) The determination of appropriate and feasi-
ble time schedules for the projects of the national
program and ensuring that projects are managed
in accordance with such schedules.
(3) The provision of full coordination of the
efforts of all Federal agencies engaged in the
support or performance of research in environ-
mental science, quite apart from efforts in appli-
cation or regulation.
(4) The establishment of organizational and
employment incentives suitable for the types of
projects that are characteristic of environmental
science through the support of national centers
and specialized institutes.
392
APPENDIX
(5) The encouragement of State and local gov-
ernments and private supporting organizations to
subscribe to the national program, as it is devel-
oped, and to the pattern of priorities adopted.
With respect to the organizations where the work of envi-
ronmental science is done, several considerations are of the
greatest importance.
Environmental science, as defined in this report,
should be viewed as a distinctive type of activity
lying between the extremes of traditional, basic
science, on the one hand, and the organizations
established by society for the application and use
of science and technology. It shares the scientific
motivations of the former and the multidisciplinary
and organizational complexity of the latter.
Various types of organizational structures should
thus be attempted, as experiments in the manage-
ment of environmental science. Two conclusions
are especially important:
(a) In academic institutions, which employ two-
thirds of the manpower in environmental science,
the need for strong departmental structures has
historically hindered the development of effective
interdepartmental programs. Within the last few
years, however, new capability and experience in
systems management, often combined with central
funding for complex problems, have given a new
vitality to multidisciplinary efforts. A few research
institutes and national laboratories have also
begun ambitious multidisciplinary studies of envi-
ronmental problems. These experiments in orga-
nization should be continued, expanded, and
followed closely.
(b) Industry possesses great capability in sys-
tems analysis and systems management, but rarely
offers the broad array of scientific competence
needed in environmental science. Government has
additional strengths, particularly in the application
of environmental science to environmental man-
agement. A more effective use of these resources
can be made by combining the talents of industry,
government, and universities in new types of
research organizations and by seeking new ap-
proaches to the management of environmental
science.
4. FUNDING FOR ENVIRONMENTAL SCIENCE
If progress in environmental science is to be made at
an acceptable rate it is essential that additional manpower be
made available both through education and through transfer
from other fields and activities. This will occur only if appro-
priate employment opportunities and incentives are provided.
The character of funding is especially important to this end.
In addition to the opportunity provided by new
types of organizations, as recommended above,
provision should be made for continuity of funding
of programs of environmental science as being
one of the principal means for attracting the best
talent.
It is further recommended that the funding of
equipment, facilities, and logistics for environ-
mental science be consistent with scientific needs
and opportunities. The highest priority should be
given to the needs of multidisciplinary teams en-
gaged in the study of environmental systems.
5. DEVELOPMENT OF ADDITIONAL MANPOWER
While it is essential that the disciplinary strength of aca-
demic institutions be maintained and increased across all fields
of science, these institutions also have a responsibility specifi-
cally with respect to the manpower of environmental science.
Although competent specialists transferring
from related disciplines can constructively enter
fields of environmental science through on-the-job
training, the process can often be faster and more
effective if retraining opportunities are available
within the educational context. Hence, it is rec-
ommended that colleges and universities consider
appropriate means for supplementary education
in environmental science for scientific and tech-
nical personnel.
Of special importance to implementing a na-
tional program for environmental science is the
existence of an informed citizenry, both as a
source of future scientists and as the necessary
basis for national understanding and motivation
of the entire program. The colleges and univer-
sities thus have a special opportunity to contribute
by the development of new curricula in which to
present the perspective of environmental science,
as well as of new courses and programs, especially
directed to the undergraduate.
Manpower needs related to environmental science are not
confined to the scientists, engineers, technicians, and others
who contribute to scientific progress. As environmental science
advances, there will be an increasing need for "natural resource
administrators" to serve in local, State, or Federal governments.
The education of these public administrators involves two
types of interdisciplinary training. On the one hand, scientists
and engineers must gain a better understanding of the social,
economic, legal, and political environment within which prac-
tical action must be sought. On the other hand, students of
public administration must gain a better perception of the
scientific process and a better understanding of how scientists
can contribute effectively to the practical solution of environ-
mental problems. It is recommended that substantial and
adequate funding be made available for these purposes.
Even with the implementation of these recommendations
only gradual progress can be anticipated. Environmental sci-
ence is too difficult, too broad in scope, and too near the begin-
ning for an effective match with societal need to be achieved
during this decade. But, correspondingly, the stakes are too
high to miss the opportunity for making the 1970's the base
on which a constructive future for mankind will be established.
393
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Bulletin of the American Meteorological Society,
50,411-421.
Committee on Atmospheric Sciences, 1966: The
Feasibility of a Global Observation and Analysis
Experiment. National Research Council, National
Academy of Sciences, Washington, D. C.
Dutton, J. A. and H. A. Panofsky, 1^70: "Clear Air
Turbulence: A Mystery May be Unfolding,"
Science, 167, 937-944.
Haltiner, G. J., 1971: Numerical Weather Predic-
tion. John Wiley & Sons, Inc., New York, N.Y.
Manabe, S. and K. Bryan, 1969: "Climate and the
Ocean Circulation," Monthly Weather Review,
97, 739-827.
Munk, W. H., 1966: "Abyssal Recipes," Deep Sea
Research, 13, 707-730.
Newell, R. E., 1971: "The Global Circulation of
Atmospheric Pollutants," Scientific American,
224, 32-42.
Petterssen, S., 1956: Weather Analysis and Fore-
casting (2nd ed.) (2 volumes). McGraw-Hill
Book Co., Inc., New York, N.Y.
Shuman, F. S. and J. B. Hovermale, 1968: "An Op-
erational Six-Layer Primitive Equation Model,"
Journal of Applied Meteorology, 7, 525-547.
Stewart, R. W., 1969: "The Atmosphere and the
Ocean," Scientific American, 221, 76-86.
Stommel, H., 1965: Gulf Stream: A Physical and
Dynamical Description. University of California
Press, Berkeley, Calif.
Stommel, H., 1970: "Future Prospects for Physical
Oceanography," Science, 168, 1531-1537.
Sverdrup, H. U., M. W. Johnson and R. H. Fleming,
1942: The Oceans. Prentice-Hall, Inc., Englewood
Cliffs, N.J.
V. SEVERE STORMS
Chalmers, J. A., 1967: Atmospheric Electricity (2nd
ed.). Pergamon Press, Inc., New York, N.Y.
Dunn, G. E. and B. I. Miller, 1964: Atlantic Hur-
ricanes (2nd ed.). Louisiana State University
Press, Baton Rouge, La.
Flora, S. D., 1954: Tornadoes of the United States.
University of Oklahoma Press, Norman, Okla.
Fujita, T. T., 1965: "Palm Sunday Tornadoes of
April 11, 1965," Monthly Weather Review, 9S,
29-69.
Gentry, R. C, 1969: "Project Stormfury," Bulletin
of the American Meteorological Society, 50, 404-
409.
Gentry, R. C, 1970: "Hurricane Debbie Modifica-
tion Experiments, August 1969," Science, 168,
473-475.
Kessler, E., 1970: "Tornadoes," Bulletin of tlie
American Meteorological Society, 51, 926-936.
Musil, D. J., 1970: "Computer Modeling of Hail-
stone Growth in the Feeder Clouds," Journal of
the Atmospheric Sciences, 27, 474-482.
Orville, R. E., 1968: "A High-Speed Time-Resolved
Spectroscopic Study of the Lightning Return
Stroke," Journal of the Atmospheric Sciences, 25,
827-856.
Palmen, E. H. and C. W. Newton, 1969: Atmos-
pheric Circulation Systems: Their Structure and
Physical Interpretation. Academic Press, Inc.,
New York, N.Y.
Rosenthal, S. L., 1970: "A Circular Symmetric
Primitive Equation Model of Tropical Cyclone
Development Containing an Explicit Water Vapor
Cycle," Monthly Weather Review, 98, 643-663.
396
SELECTED REFERENCES
Sulakvelidze, G. K., 1969: Rainstorms and flail
(translated from Russian). U.S. Department of
Commerce (TT 68-50446), National Technical
Information Service, Springfield, Va.
Uman, M A., 1069: Lightning. McGraw-Hill Book
Co., Inc., New York, N.Y.
VI. PRECIPITATION AND REGIONAL WEATHER
PHENOMENA
Appleman, H. S. and F. G. Coons, Jr., 1970: "The
Use of Jet Aircraft Engines to Dissipate Warm
Fog," Journal of Applied Meteorology, 9, 464-
466.
Battan, L. J., 1967: "Silver-Iodide Seeding and Pre-
cipitation Initiation in Convective Clouds,"
Journal of Applied Meteorology, 6, 317-322.
Beckwith, W. B., 1968: "An Analysis of Airport
Fog Dispersal Operations with Giant Hygro-
scopic Nuclei," Journal of Applied Meteorology,
7, 860-869.
Biswas, K. R., R. K. Kapoor, K. K. Kanuga and
B. V. Ramanta Murty, 1^67 : "Cloud Seeding Ex-
periment Using Common Salt," Journal of Ap-
plied Meteorology, 6, 914-923.
Carlson, T. N. and J. M. Prospero, 1972: "The
Large-Scale Movement of Saharan Air Out-
breaks over the Northern Equatorial Atlantic,"
Journal of Applied Meteorology, 11, 283-297.
Committee on Atmospheric Sciences, 1966: Weather
and Climate Modification : Problems and Pros-
pects. National Research Council, National Acad-
emy of Sciences, Washington, D. C.
Fleagle, R. G. (ed.), 1968: Weather Modification,
Science and Public Policy. University of Wash-
ington Press, Seattle, Wash.
Flowers, E. C, R. A. McCormick and K. R. Kurfis,
1969: "Atmospheric Turbidity over the United
States, 1961-1966," Journal of Applied Meteor-
ology, 8, 955-962.
Jiusto, J. E., R. S. Pilie and W. C. Kocmond, 1968:
"Fog Modification with Giant Hygroscopic Nu-
clei," Journal of Applied Meteorology, 7, 860-
869.
Mielke, P. W., L. O. Grant and C. F. Chappell,
1970: "Elevation and Spatial Variation Effects
of Wintertime Orographic Cloud Seeding/'
Journal of Applied Meteorology, 9, 476-488.
Namias, J., 1966: "Nature and Possible Causes of
the Northeastern United States Drought During
1962-65," Monthly Weather Review, 94, 543-
554.
Ramage, C. S., 1971: Monsoon Meteorology. Aca-
demic Press, Inc., New York, N.Y.
Riehl, H., 1954: Tropical Meteorology. McGraw-
Hill Book Co., Inc., New York, N.Y.
Simpson, J. and V. Wiggert, 1970: "Rainfall En-
hancement by Dynamic Cloud Modification,"
Science, 170, 127-132.
Sugg, A. L., 1968: "Beneficial Aspects of the Tropi-
cal Cyclone," Journal of Applied Meteorology,
7, 39-45.
Taubenfeld, H. J. (ed.), 1970: Controlling the
Weather: A Study of Law and Regulatory Proc-
esses. The Dunnellen Co., Inc., New York, N.Y.
VII. WATER RESOURCES, FORESTRY AND
AGRICULTURE
Bormann, F. H., G. E. Likens, D. W. Fisher and
R. S. Pierce, 1968: "Nutrient Loss Accelerated
by Clear-Cutting of a Forest Ecosystem," Science,
159, 882-884.
Bosselman, F. and D. Callies, 1972: The Quiet
Revolution in Land Use Control. Council on En-
vironmental Quality, U.S. Government Printing
Office, Washington, D. C.
Byerly, T. C, 1966: "The Role of Livestock in Food
Production," Journal of Animal Science, 25, 552-
566.
Calder, R., 1962: Common Sense about a Starving
World. MacMillan Co., Inc., New York, N.Y.
Coffman, W. P., K. W. Cummins and J. C. Wuy-
check, 1971: "Energy Flow in a Woodland Stream
Ecosystem: I Tissue Support Trophic Structure
of the Autumnal Community," Archives of Hy-
drobiology, 68, 232-276.
Guy, H. P., 1970: Sediment Problems in Urban
Areas. U.S. Geological Survey Circular 601-E,
U.S. Department of Interior, Washington, D. C.
Hayami, Y. and V. W. Ruttan, 1971: Agricultural
Development: An International Perspective. The
Johns Hopkins Press, Baltimore, Md.
Kneese, A. V., 1965: Economic and Related Prob-
lems on Water Resources Management. Resources
for the Future Reprint 55, Washington, D. C.
Loomis, R. S. and W. A. Williams, 1963: "Maxi-
mum Crop Productivity: An Estimate," Crop
Science, 3, 67-72.
Oglesby, T. R., C. A. Carlson and J. A. McCann
(eds.), 1972: River Ecology and Man. Academic
Press, Inc., New York, N.Y.
Panel on the World Food Supply, 1967: The World
Food Problem, Vols. I and 11. President's Science
Advisory Committee, U.S. Government Printing
Office, Washington, D. C.
Schmitt, W. R., 1965: "The Planetary Food-Poten-
tial," New York Academy of Science Annals,
118, 645-718.
National Water Commission, 1973: Water Policies
for the Future. U.S. Government Printing Office,
Washington, D. C.
397
SELECTED REFERENCES
Watt, K. E. F., 1967: Ecology and Resource Man-
agement: A Quantitative Approach. McGraw-
Hill Book Co., Inc., New York, N.Y.
VIII. AQUATIC ECOSYSTEMS
Bardach, J. E. and J. H. Ryther, l^oS: The Status
and Potential of Aquaculture, II, Particularly
Pish Culture. U.S. Department of Commerce
(BP 177-768), National Technical Information
Service, Springfield, Va.
Barnes, H., 1964-72: Oceanography and Marine
Biology, An Annual Review. George Allen and
Unwin Ltd., London, England.
Coker, R. E., 1962: This Great and Wide Sea.
Harper and Row, Inc., New York, N.Y.
Costlow, J. D., Jr. (ed.), 1971: Fertility of the Sea,
1 & 2. Gordon and Breach Science Publishers,
Inc., New York, N.Y.
Gannon, J. E., 1969: Great Lakes Plankton Investi-
gations: A Bibliography. Special Report 7, Uni-
versity of Wisconsin Center for Great Lakes
Studies, Madison, Wis.
Hardy, A., 19o5: The Open Sea, I & 2. Houghton
Mifflin Co., Inc., New York, N.Y.
Hedgpeth, J, W. (ed.), 1957: Treatise on Marine
Ecology, Vol. 1. Memoir of the Geological So-
ciety of America, Vol. 67 (No. 1), Boulder, Colo.
Hill, M. N. (ed.), 1963: The Sea (Vol. 2). John Wiley
and Sons, Inc., New York, N.Y.
Hutchinson, G. E., 1957: Treatise on Limnology,
1. John Wiley and Sons, Inc., New York, N.Y.
Jorgensen, C. B., 1966: The Biology of Suspension-
Feeding Organisms. Pergamon Press, Inc., New
York, N.Y."
Marshall, S. M. and A. P. Orr, 1^55: Biology of a
Marine Copcpod. Oliver and Boyd, London,
England.
Milway, C. P., 1968: Eutrophication in Large Lakes
and Impoundments. Organization for Economic
Cooperation and Development, Paris, France.
Moiseev, P. A., 1969: The Living Resources of the
World Ocean (translated from Russian). U.S.
Department of Commerce (TT 71-50026), Na-
tional Technical Information Service, Springfield,
Va.
Planning Committee for the International Sym-
posium on Eutrophication, 1969: Eutrophication:
Courses, Consequences and Correctives. National
Academy of Sciences, Washington, D. C.
Raymont, J. F. G., 1963: Plankton and Productivity
of the Oceans. Pergamon Press, Inc., New York,
N.Y.
Revelle, R., 1969: "The Ocean," Scientific Ameri-
can, 221, 54-65.
Ruttner, F., 1952: Fundamentals of Limnology. Uni-
versity of Toronto Press, Toronto, Canada.
Ryther, J. H., 1969: "Photosynthesis and Fish Pro-
duction in the Sea," Science, 166, 72-76.
Ryther, J. H. and J. E. Bardach, 1968: The Status
and Potential of Aquae ultitre, I, Particularly In-
vertebrate and Algae Culture. U.S. Department
of Commerce (BP 177-767), National Technical
Information Service, Springfield, Va.
Steele, J. H. (ed.), 1970: Marine Food Chains. Uni-
versity of California Press, Berkeley, Calif.
IX. TERRESTRIAL ECOSYSTEMS
Andrewartha, H. G. and L. C. Birch, 1954: The Dis-
tribution and Abundance of Animals. University
of Chicago Press, Chicago, 111.
Cooper, C. F., 1961: "The Ecology of Fire," Scien-
tific American, 204, 150-160.
Darling, F., 1960: "Wildlife Husbandry in Africa,"
Scientific American, 203, 123-138.
Darlington, P. J., 1957: Zoogeography. John Wiley
and Sons, Inc., New York, N.Y.
Dasmann, R. F., 1968: Environmental Conservation
(2nd ed.). John Wiley and Sons, Inc., New York,
N.Y.
Ehrlich, P. R., 1968: The Population Bomb. Ballan-
tyne Books, Inc., New York, N.Y.
Ehrlich, P. R. and A. H. Ehrlich, 1970: Population,
Resources, Environment: Issues in Human Ecol-
ogy. W. H. Freeman and Co., San Francisco,
Calif.
Hairston, N. G., F. E. Smith and L. B. Slobodkin,
1960: "Community Structure, Population Con-
trol and Competition," American Naturalist, 94,
421-425.
Hardin, G., 1968: "The Tragedy of the Commons,"
Science, 162, 1243-1248.
Hazen, W. E., 1964: Readings in Population and
Community Ecology. W. B. Saunders Co., Phila-
delphia, Pa.
Huffaker, C. B. (ed.), 1971: Biological Control.
Plenum Press, New York, N.Y.
Hutchinson, G. E., 1970: "The Biosphere," Scien-
tific American, 223, 44-53.
Kendeigh, S. C, 1961: Animal Ecology. Prentice-
Hall, Inc., Englewood Cliffs, N.J.
Kormondy, E. J. (ed.), 1965: Readings in Ecology.
Prentice-Hall, Inc., Englewood Cliffs, N.J.
Lack, D., 1954: The Natural Regulation of Animal
Numbers. The Oxford University Press, London,
England.
Odum, E. P. (ed.), 1971: Fundamentals of Ecology.
W. B. Saunders Co., Philadelphia, Pa.
398
SELECTED REFERENCES
Odum, E. P., 1Q63: Ecology. Holt, Rinehart and
Winston, Inc., New York, N.Y.
Odum, H. T., 1971: Environment, Power, Society.
John Wiley and Sons, Inc., Interscience Pub-
lishers, New York, N.Y.
Van Dyne, G., 1969: The Ecosystem Concept in
Natural Resource Management. Academic Press,
Inc., New York, N.Y.
Workshop on Global Ecological Problems, 1972:
Man in the Living Environment. Institute of
Ecology Report, University of Wisconsin Press,
Madison, Wis.
ENVIRONMENTAL CONTAMINANTS
Agricultural Board, 1972: Pest Control Strategies
for the Future. National Research Council, Na-
tional Academy of Sciences, Washington, D. C.
Blanchard, D. C. and L. D. Syzdek, 1972: "Concen-
tration of Bacteria in Jet Drops from Bursting
Bubbles," Journal of Geophysical Research, 77,
5087-5099.
Brittin, W. E„ R. West and R. Williams (eds.),
1972: Air and Water Pollution. Colorado Asso-
ciated University Press, Boulder, Colo.
Butcher, S. S. and R. J. Charlson, 1972: An Intro-
duction to Air Chemistry. Academic Press, Inc.,
New York, N.Y.
Cairns, J. Jr., G. R. Tonza and B. C. Parker, 1972:
"Pollution Related Structural and Functional
Changes in Aquatic Communities with Emphasis
on Freshwater Algae and Protozoa," Proceedings
of the Academy of Natural Sciences of Philadel-
phia, Pa., 124, 79-127.
Committee on Plant and Animal Pests, 1969: Insect
Pest Management and Control. National Research
Council, National Academy of Sciences, Wash-
ington, D. C.
Division of Medical Sciences, 1962: Tropical Health:
A Report on a Study of Needs and Resources.
National Research Council, National Academy
of Sciences, Washington, D. C.
Eagen, B. A. and J. R. Mahoney, 1972: "Applica-
tions of a Numerical Air Pollution Transport
Model to Dispersion in the Atmospheric Bound-
ary Layer," Journal of Applied Meteorology, 11,
1023-1039.
Garlick, J. P. and R. W. J. Keay, 1970: Human
Ecology in the Tropics. Pergamon Press, Inc.,
New York, N.Y.
Goldberg, E. A. (convener), 1972: Baseline Studies
of Pollutants in the Marine Environment and
Research Recommendations. The IDOE Baseline
Conference, May 24-26, 1972, New York, N.Y.
Gregory, P. H., 1973: Microbiology of the Atmos-
phere (2nd ed.). Halsted Press, New York, N.Y.
Hidy, G. M. and J. R. Brock, 1^70: The Di
of Aerocolloidal Systems. Pergamon Press, Inc.,
New York, N.Y.
Leighton, P. A., 1961: Photochemistry of Air Pollu-
tion. Academic Press, Inc., New York, N.Y.
Ocean Science Committee, 1971: Marine Environ-
mental Quality. National Research Council, Na-
tional Academy of Sciences, Washington, D. C.
Olson, T. A. and F. J. Burgess (eds.), 1967: Pollu-
tion and Marine Ecology. John Wiley and Sons,
Inc., Interscience Publishers, New York, N.Y.
Pimental, D., 1971: Ecological Effects of Pesticides
on Non-Target Species. Office of Science and
Technology, U.S. Government Printing Office,
Washington, D. C.
Rabb, R. L. and F. E. Guthrie (eds.), 1970: Concepts
of Pest Management. North Carolina State Uni-
versity Press, Raleigh, N.C.
Singer, S. F. (ed.), 1970: Global Effects of Environ-
mental Pollution. Springer-Verlag, New York,
N.Y.
Stern, A. C. (ed.), 1968: Air Pollution (2nd ed.).
Academic Press, Inc., New York, N.Y.
Sykes, G. and F. A. Skinner (eds.), 1971: Microbial
Aspects of Pollution, A Symposium. Academic
Press, Inc., New York, N.Y.
Wood, D. L., R. M. Silverstein and M. Nakajima,
1970: Control of Insect Behavior by Natural
Products. Academic Press, Inc., New York, N.Y.
XI. HUMAN ADAPTATION TO ENVIRONMENTAL
STRESS
Aiger, J. S., 1971: "Early Cultural Identification in
Southwestern Alaska," Science, 171, 87-88.
Baker, P. T., 1969: "Human Adaptation to High
Altitudes," Science, 163, 1149-1156.
Baker, P. T. and J. S. Weiner (eds.), 1966: The
Biology of Human Adaptability. Oxford Uni-
versity Press, London, England.
Chagnon, N. A., 1968: Yanomama: The Fierce Peo-
ple. Holt, Rinehart and Winston, Inc., New
York, N.Y.
Cohen, S. I., M. Deane and J. R. Goldsmith, 1969:
"Carbon Monoxide and Survival from Myo-
cardial Infarction," Archives of Environmental
Health, 19, 510-517.
Goldsmith, J. R., 1969: "Air Pollution Epidemiol-
ogy," Archives of Environmental Health, 18, 516-
522.
Goldsmith, J. R., 1970: "Contributions of Motor
Vehicle Exhaust, Industry, and Cigarette Smok-
ing to Community Carbon Monoxide Exposures,"
Annals of the New York Academy of Sciences,
174, 122-134.
399
SELECTED REFERENCES
Hanna, J. M., 1971: "Responses of Quechua Indians
to Coca Ingestion during Cold Exposure/'
American Journal of Physical Anthropology, 34,
273-277.
Little, M. A., R. B. Thomas, R. B. Mazess and
P. T. Baker, 1971: "Population Differences and
Developmental Changes in Extremity Tempera-
ture Responses to Cold Among Andean Indians,"
Human Biology, 43, 70-91.
Livingstone, F. B., H. Gershowitz, J. V. Neel, W. W.
Zuelzer and M. D. Solomon, 1960: "The Distri-
bution of Several Blood Group Genes in Liberia,
the Ivory Coast and Upper Volta," American
Journal of Physical Anthropology, 18, 161-178.
Milan, F. A., 1968: "The International Study of
Eskimos," Arctic, 21, 123-126.
Neel, J. V., 1970: "Lessons from a Primitive Peo-
ple," Science, 170, 815-822.
Neel, J. V., VV. R. Centerwall, N. A. Chagnon and
H. L. Casev, 1970: "Notes on the Effect of
Measles and Measle Vaccine in a Virgin-Soil
Population of South American Indians," Ameri-
can Journal of Epidemiology, 91, 418-429.
Ward, R. H. and J. V. Neel, 1970: "Gene Frequen-
cies and Microdifferentiation among the Makiri-
tore Indians, IV — Comparison of a Genetic Net-
work with Ethnohistory and Migration Matrices:
A New Index of Genetic Isolation," American
Journal of Human Genetics, 22, 538-561.
Wohlwill, J. F. and D. H. Carson (eds.), 1972: En-
vironment and the Social Sciences: Perspectives
and Applications. American Psychological Asso-
ciation, Inc., Washington, D. C.
World Health Organization, 1972: Health Hazards
of the Human Environment. World Health Orga-
nization, Geneva, Switzerland.
Youseff, M. K., S. M. Horvath and R. W. Bullard,
1972: Physiological Adaptations: Desert and
Mountain. Academic Press, Inc., New York,
N.Y.
400
INDEX
Absorption
radiation aerosols, 58, 89
water in forest canopy, 202
Abyssinian Plateau, Africa, 123
Accademia del Cimento, Florence, Italy, 51
Acclimatization: high altitudes, 380, 381, 382
Accumulation: cloud zone, 149, Fig. V-13
Acoustic waves: volcanic eruptions, 44
Actinic rays in urban areas, 117
Adaptation
climatic
high altitude, 379-385
skin color, 375
genetic
see Natural selection
human
limitations, 387
to air pollution, 338, 385-390
to high altitude, 379-385
to tropical climates, 378
technological, 338
Adelie penguins, 232
A-disciplinary problems
see Multidisciplinary problems
Advection in water cycle, 202
AEC, see Atomic Energy Commission, U.S.
Aerobiology, 339-349
particulates, Fig. X-6
Aerobiology Program, U.S. (IBP), 339, 342,
344
Aerosols
in atmosphere, 55, 58, 69
effect on circulation, 89, 91
effect on climate, 64, 116
effect on precipitation, 192
effect on radiation balance, 67, 68
in troposphere, detection by radar, 112
see nlso Nucleating agents; Nuclei;
Particulates
Aesthetics
Corpus Christi Bay, Fig. VIII-10
forest management, 293
lakes, 260
of the environment, 338
oil on ocean surface, 361
Africa
agriculture, 74, 215, 220, 242, 291, 297
arable land, Fig. VII-8
atmosphere-ocean system, 82, 191, 192,
193, 194, 358
climatic change, 51, 52, 69, 72
data networks, 59
earth processes, 27, 28, 32, 33, 44
environmental contamination, 217, 329,
Fig. X-12, 364-367
human adaptation, 376, 377
severe storms, 123, Fig. V-l, 154,
Fig. VI-10
tropical research facilities, 185
Aging processes
human
air pollution, 388
at high altitudes, 382, 383
lakes, 268
Agricultural planning
crop management, 288
soil studies, 291
tropical areas, 295-298, 301
urban-induced weather changes, 115
Agriculture, 215-221
cattle, 74
crop rotation, 296
effects of parasitic disease on labor,
Fig. X-20
effects of smog, 337
lessons from fossil plant studies, 74
pesticides and yields, Fig. X-12
polluting drainage, 248, 261, 273
water use, Fig. VII-1, 204
see also Agricultural planning; Farming;
Land use; Soils
Agriculture, U.S. Department of
aerobiology research, 344
agricultural science, 218
lighting research, 160
see also Forest Service, U.S.
Air: composition, 329
Air Force, U.S., 13, 15, 102, 181
see also Air Weather Service, U.S.
Air Force
Air pollution, see Pollution, Atmospheric
Air quality
control regions, 334
measurement, 333, Fig. X-4
models, 335-336
standards, 334
Air-sea rhythms, see Ocean-atmosphere
system
Air Weather Service, U.S. Air Force, 13,
102, 103
Aircraft
cloud seeding, 154, 173, 176
fog seeding, 180, 181, 182, 183
jets, 65, 69, 103
lightning and, 157-158
radar, 111
turbulence and, 105, 106, 107, Fig. IV-10
weather monitoring, 98, 124, 129, 193, 194
see also Aviation
Airports
air pollution measurement, 334
fog dispersal, 181, 182, 183
weather prediction needs, 101, 102, 103,
104
Aitken, J., 193
Aitken nuclei, 193
Alabama, 147
Alaska, 32, 69, 87, 181
earthquakes, 35, 40
marine areas, 242, 244, 246
polar ecosystems, Fig. IX-15, 314,
Fig. IX-16
volcanoes, 41, 42, 44, 46
weather modification, 101
Alazani Valley, Caucasus Mts., 151
Albedo of the earth, 66-69, Fig. III-7, 70, 71
atmospheric constituents, 89
climate and, 51, 52, 55
effect of dust, 194
tropical forests, 298
urban areas, 116
Alberta, Canada, 41, 154
Alder (tree), 208
Aleutian Islands, 35, 36, 44, 46
Alewives
trophic dynamics of Great Lakes, 227,
228, Fig. VIII-2, Fig. VIII-14, 262,
263, 264, 266
Algae
air pollution, Fig. X-6, 343, 345
Great Lakes, 264, 270
in chert deposits, 52
in forest ecosystem, 292
in harbors and lagoons, 233
in oceans, 236
Lake Washington, 272, Fig. VIII-17
macroscopic, in aquaculture, Fig. VIII-11
trophic dynamics, 225, 226, 227, 228
tundra 313, 314
Allergens, Airborne, 340, 342, 345-349
Alpha Helix, R.V. (ship), 233
Alpine glaciers, 52
Alps: plate deformation, 28
Altitude: human adaptation, 379-385
Aluminum oxides in tropical forests, 295
Amarillo, Texas, 204
Amazon River, 34, 187, 300
Amchitka Island, Aleutians, Alaska, 46
America, see United States
Amery Ice Shelf, Antarctica, 84
Amitrole herbicide, 207
Ammonia: volcanoes, 43
Anaerobic basins, 55
Anakawa, Akio, 88
Anchovy fisheries
food potential, 237, 238
Peru, 234
Andean Mts., S.A., 32
Anderson, J. P., 306
Anemometers, 347
Angell, James K., 109
Angstrom, A. J., 71
Animals
energy budget, 289
horse, Fig. IX-7
ethology, 376
experimental
air pollution studies, 387-388, 389
high altitude medicine, 384
fish protein as food for, 227-247
in forest ecosystems, 292, 302-305
fire and, 310, 312
tropics, 298
water quality and, 212
in tundra ecosystems, Fig. IX-16
plant eaters, 225
response in ecosystem, 289
source of food for man, 74, 217, 218
in oceans, 236
see also Carnivores; Game animals;
Herbivores; Livestock; Mammals
Anions: forest ecosystems, 294
Antarctic Treaty, 313, 314
401
INDEX
Antarctica
contamination, 330, 360
ecosystems, 313, 314
food chain, Fig. VIII-6, 351
food production, 217, 241
glaciation, 53, 54, 55
oceanic circulation and, 78, 83-84,
Fig. IV-3, 98, 231-233, 239
see also Krill
Anticyclones
drought, 165, 167
prediction of, 93, 94
Apollo missions, 14, 158
Appalachian Mts., 31, 118
APT, see Automatic Picture Transmission
Aquaculture prospects, 250-253
Aquatic ecosystems: modeling, 282
Aquatic plants, 236, 302
Aquifers, 203
Aquitards, 203
Arabian Sea, 358
Areata, Cal., 181
Arctic regions, 78, 79
air-sea rhythms, 86, 87
ecosystems, 313-315
food production, 217
pack-ice behavior, 58
see also Antarctica
Ardrey, William B., 376
Argentina, 154, 241, 242, 369
Argonne National Laboratory (AEC), 257
Arid regions
Africa
source of dust in western hemisphere,
191
source of hurricanes, 123
maintenance of the biosphere, 280-285
gramagrass output, Fig. IX-4
mosquito submodel, Fig. IX-3
subtropical anticyclones, 165
water supply, 198
Arizona
groundwater, 204
range management, 74
seismic refraction profile, 29, 31
University of, 306
Arkansas, 308
Armed Forces Epidemiological Board,
U.S., 365
Armenia, 152
Armstrong, Bruce W., 388
Army, U.S., 136
Army Air Force, U.S., 46
Army Medical Research and Development
Command, U.S., 365, 379
Aromatics, 361
Arsenic poisoning, 322, 357
Asama volcano, Japan, 45
Asbestos, 320
Ash, Volcanic
as contaminant, 55, 56, 68, 71, 72, 329
falls and flows, 40, 41, 42, 44, 45
Asia
agriculture, 220, 238, 251, 252, 297
climatic change, 57
data networks, Fig. IV— 7
environmental contamination, 364, 365
precipitation, Fig. VI-10, 185
Asphalts, 361
Assimilation capacity of lake water, 270
Asthma, 319, 385
Astrup, Paul, 386, 388
Atlanta, Ga., 189
Atlantic coast, 38, 135
Atlantic Ocean
air-sea system, 78, 83, 84
climatic change, 57, 58
conservation, 246
data measurement, 79, 86, 91, 360
drought, 165, 167, 188
earth processes, 27, 28, 33, 53, 55
environmental contamination, 191, 192,
194, 329, 358
precipitation, 189
severe storms, 123, Fig. V-l, 126, 132, 147
weather forecasting, 185
Atlas, D., 109
Atmosphere, 3, 34, 52 158, 257
behavior, 62, 63
composition, 55, 286, 287
upper, 3, 10, 11-13, 167, 175
see n/so Pollution, Atmospheric
Atmospheric circulation, 89-92
global, 64, 72
indicated by tree rings, Fig. Ill— 5
topics, 125, 188
dusts, 192
monsoons, 184
urbanization effects, 116
Atomic Energy Commission, U.S., 46,
Fig. VI-11,259
see also Argonne National Laboratory;
Brookhaven National Laboratory
Auroral electrojet, 10
Auroral substorms, 5, 8
Australia
agriculture, Fig. VII-8, 219
air-sea system, 358
climatic change, 57
earth processes, 44
ecosystems, 291, 297
human adaptation, 376
precipitation, 184, 185
water resources, 242
weather modification, 188
Automatic Picture Transmission (APT), 185
Avalanches, 42, 212
Aviation
accidents, 108, 111, 117
noise pollution, 326
weather forecasting for, 101, 102, 103
weather reporting from, 105, 106
see also Aircraft
Axelrod, Herman D., 330
Avres, S. M, 388
Azerbaidjan, U.S.S.R., 152
Azores Islands, 35, 135
B
Backfires in forests, 310
Backus, Richard H., 361, 363
Bacteria
air pollution, Fig. X-6, 342
in forest ecosystem, 292
oxidation of floating oil lumps, 362
soil, oxidation of CO, 358
Baja California, 240
Balchum, Oscar Joseph, 388
Baldwin Hills Dam, Los Angeles, Cal., 204
Baltic Sea, 52
Barbados, Antilles, 191, 193, 194, 329,
330, 358
see also BOMEX
Barnacles, 241
on petroleum lumps, 361, 362, 363
Basalt, 29
Basin and Range Province, Nevada, 29, 31,
204
Batchelder, Arthur R., 306
Bears, 302
Beaufait, William R., 306
Beaver, 304
Bees and other pollinators, 351, 354, 355
Behavioral differences among populations,
373, 374, 376
Benchmark stations, 59, 331
Benefit/cost analysis
effects of technology on the environ-
ment, 338
environmental management, 283
fog dispersal at airports, 180-181,
Fig. VI-9, 183
forest management, 206
pest controls, 351, 353, 356
water quality in Great Lakes, 270
weather changes, 172
Bengal, Bay of, 184
Bennett, Dudley W„ 389
Benthic marine communities, 231, 232
Benzene hexachloride, see Dieldrin
Bering Sea, 74, 242, 244, 246
Bermuda, 191
Bermuda High, 165
Berry, Lester J., 219
Beryllium, 321
Bezymianny (volcano), 40
Biological effects
air contaminants, 332
pesticides, 351
thermal discharges in lakes, 259
Biological extinction of animals
climatic changes and, 73-74
magnetic field reversals and, 25
Stone Age hunters, 74
Biological materials as air pollutants, 339
Biomes, Major world, 285, Fig. IX-5
deciduous forest, 298
tundra, Fig. IX-15, 314, 315
see also Grassland ecosystem
Biosphere, 3, 301
Birds
malaria systems, 365
pesticides and, 351, 353, 357, 359
Bishop tuff, Cal., 42
Bivalves, 232, 237
Bjerknes, J., 167, 189
Black spruce, 311
Blackberries, 352
Blast waves from solar flares, 6
Blind areas for weather observations, 98
Blood groups, 373, 374
Bobcat, 302
402
INDEX
BOMEX (Barbados Oceanographic and
Meteorological Experiment), 125, 185,
Fig. VI-11
Bormann, F. H., 294
Boundary layer of plant evaporation,
200, 201
Braham, Roscoe R., 171
Brazil
air-sea system, 190
climatic change, 52
drought, 188
environmental disease, 367
human adaptation, 374, Fig. XI-1
mineral deposits, 33
range management, 74
Breton Island, Miss., 136
Bristlecone pine: tree ring studies, 61
Bronchitis, 319, 385, Fig. XI-8, 390
Brook, J., 139
Brookhaven National Laboratory (AEC),
348
Brooklyn Navy Yard, New York, 362
Browning, Keith A., 149
Brownsville, Texas, 135
Bryan, Kirk, Jr., 87
Bryozoa, 232
Budyko, M. I., 67, 68
Buell, P., 388
Building codes
earthquake hazards, 39
hurricane protection, 136
Buildings and structures
effects of air pollution, 319
effects of smog on, 337
polluting capacity of houses, 327, 385
see also Construction industry
Buoys, 90, 190
ocean studies, 78, 79, 80, 82, 84, 87, 100
Bureau of Reclamation, U.S., 171, 172
Burkett, Howard B., 365
Burma, 184, 185
Cactus, Prickly-pear, 297
Cadmium poisoning, 322
Calcite, 193
Calcium
chloride, 174
increase in Great Lakes, 268
California
crust of earth, 29, 30, Fig. VII-3, 204
earthquakes, 26, 28, 30, 31, 33, 35 36, 37,
Fig. II— 7, 39, 40
environment 336, 337, 351, 352, Fig. X-13,
385, 386, 390
fog dispersal, 181, 182
forests, 61, 207, Fig. VII-5
ocean areas, 87, 231, 240, 242, 245, 361,
362
trees, 61
volcanoes, 40, 41, 44
water, 33, 166, 199, 204, 211
California, University of, 66
California current: data measurements, 78
California Institute of Technology
contamination research, 330
Cambrian era, 52
Cambridge Research Laboratories
(U.S. Air Force), 13
Cameroons, W. Africa, 192
Canada
air-sea system, 106
climatic change, 73
earth processes, 39
ecosystems, 314
environmental contamination, 267
severe storms, 133, 147, 151
Canton Island, Pacific, observatory, 84,
Fig. 1V-4, 86, 87, 88
Cape Cod, Mass., 135
Cape Thompson, Alaska, 314
Cape Verde Islands, 135
Carbamates, 355
Carbon, 22, 32
carbon 14
insecticides, 234
measure of productive capacity of the
sea, 236
circulation in forest ecosystems, 301
lake nutrients, 272
pollution particles, 358, 362
Carbon dioxide (CO^)
advection in photosynthesis, 202
cloud seeding, 173, 174, 175
fog seeding, 180, 182, 183
hailstorm seeding, 153
heat balance of the earth, 287
in atmosphere, 34, 55, 56, 57, 58, 64, 89
120, 329, 333, 337, 357-358
amounts present, 67, 68, Fig. III-9,
Fig. 111-10, 72
high altitudes, 382
moist tropics, 330
ocean absorption, 82, 233
urban areas, 119
land cultivation and changes in, 300
plant growth, 288, 289
quantity affected by man's activities, 286
Carbon monoxide (CO)
air pollution and, 320, 330, 333, 337, 338,
358
human adaptation, 385-390
Carboniferous era, 329
Carboxyhemoglobin, 338, 388, Fig. XI-9
Caribbean Sea
atmospheric dust, 191, 192
earth processes, 53, 54
severe storms, 123, Fig. V-l, 135
weather forecasting, 185
weather modification, 188
Carnivores
food chain, 225, Fig. VIII-11, 286,
Fig. IX-6, 304
Carp in Great Lakes, 261, 263, 266
Cascade Range, Wash.-Cal., 40
CAT, see Clear air turbulence
Catfish, 251
Cations
forest ecosystems, 294
Caucasus Mountains, U.S.S.R., 151, 152,
358, Fig. X-15
Cenozoic era, 52, 55
Center for Short-Lived Phenomena,
Cambridge, Mass., 47
Central America, 35, 123, 246
Central Plains: weather, 146, 165
Ceraunograms: tropical weather fore-
casting, 187
Cerra Negro (volcano), Costa Rica, 44
Chad Lake, Africa, 52
Chagas' disease, 217, 369-370
Chain reactions
ecological balance of Great Lakes, 261
forest ecosystem response to population
changes, 300
hurricane development, 125
ocean-atmosphere system, 88
Changnon, S. A., Jr., 152
Chaparral, 298
Charleston, S. C, 38
Charlson, Robert J., 330
Chemicals
atmospheric pollutants, 118, 119, 332
marine contaminants, 357-360
see also Fertilizers; Insecticides;
Pesticides; Pollution, Atmospheric
Chemiluminescence quenching, 331
Chert deposits, 52
Chicago, 111., 113, 119, 257
Children, Growth of
air pollution and, 388
high altitudes, Fig. XI-6, 385
tropical regions, 378
Chile, 240, 241, 242, 369
China, 184, 185, 186, 216, 357
China Seas, 184
Chitin, 240
Chlorinated hydrocarbons
use on forest lands, 206
water-vapor pollution, 337
see also Insecticides; Pesticides
Chlorine in Great Lakes, 268
Chloroplasts, 288
Cholesterol stores, 385
Christmas Island, 87
Chromium poisoning, 322
Chromosphere, 5
Chubs, see Ciscoes
Chukchi Sea, 246
CIC (Committee on Institutional
Cooperation), 269
Cigarette smoking: health hazards, 385,
Fig. XI-8, 387, 388, 390
Cincinnati, Ohio, 114
Circular storms, 123
Circulatory diseases, 388
Ciscoes: Great Lakes, 261, 262, 263, 264
Citrus groves, 355
Clathration process: fog dispersal, 183
Claveran, Ramon, 306
Clay minerals
ice nuclei, 192
in ocean sediments, 358
Clear air turbulence, 105-112
Clear cutting
forests, 207, 210, 213
tropical areas, 296
Climate, 13, 34, 59, 62, 72
aerobiology, 344
affected by
air-ocean system, 82, 85
gravitational field, 51
403
INDEX
hurricanes, 133
volcanic ash, 41
water supply, 198, 212
change, 51-74, 180
regional, 57, 60
models, 64, 120
control, 55, 57, 58, 89
urbanization and, 113-120
vegetation fire and, 306
world's major biomes, Fig. IX-5
see also Precipitation; Weather
Cloud seeding
hail suppression, 151-155
hurricane modification, 126
lightning control, 158, 160-161,
optimum conditions, Fig. VI-5
possible results, 57
precipitation changes, U.S., 170-179
Project STORMFURY, 128-132
seeding materials, Fig. VI-6, 178
simulation, Fig. VI-6
see also Seeding techniques for fog
Clouds, 68, 108, 113, 174, 175
albedo of the earth and, 66, Fig. III-7,
c8, 69, 71
atmospheric circulations, 89, 165
billow, 109
cirrus
contrails and, 69
satellite measurement of, 103
cumulonimbus
Caribbean area, 188
hailstorms and, 154
monsoon areas, 187, 188
tornadoes and, 138, 144
cumulus
atmosphere-ocean system, 67, 91
cloud seeding, Fig. VI-6
dust and, 191, 192
hailstorms and, 150
hurricanes and, 125, 128, 130
nuclei, 170
cumulus congestus
tropical areas, 188
lightning from, Fig. V-15
modification, 188
monsoon areas, 187
nucleation centers, 329
predictions, 102, 103
stratus clouds
precipitation, 173
studies
clusters, 126
via satellites, 87, 123
weather forecasting, Fig. IV-6, 95
water vapor and, 337
Coast Ranges, Cal., 29, 30
Coastal areas
damage by hurricanes, 128, 133, 135
entrapment of water, 255
lakes
upwelling, Fig. VIII-12
marine productivity, 233, 235, Fig. VIII-7
pollution, 254
tundra ecosystem, Fig. IX— 16
see also Shore zones
Coastal Studies Institute, Louisiana State
Univ., 134
Cobalt: lake nutrient, 272
Coffee cultivation, Fig. VII-9
Cohen, S. I., 390
Cold fog, 180, 182
Colorado
cloud seeding, 171, 172, Fig. VI-5
hail storm research, 154
seismic monitoring, 31, 39
Colorado Plateau, 2"
Columbia, Md., 118
Columbia Plateau, Wash., 29
Columbia River, Wash. -Ore., 40
Commerce, U.S. Department of, Fig. VI-11
Commission for Climatology, World
Meteorology Organization (WMO), 59
Community air pollution, 319-321
Competition among plant species, 289
Computers
ecosystem modeling
analogue, 281
digital, 281, 285
hybrid, 281, 285
forest ecosystems, 300
simulation
atmosphere-stagnation periods, 118
ocean productivity, 233, 235
use, 16, 352
space efforts, 16
weather forecasting, 91, 94, 97, 99, 101,
103, 104, 125, 141, Fig. V-10, 185
Condensation: fog dispersal, 181
Congenital defects, 383, 384
Conglomerate rocks, 203
Coniferous forests, see Forests
Connecticut, 73, 336
Conservation
air quality models, 335
aquaculture and, 251
gene pool, 278
water, 259
Constance, Lake (Ger.-Aus.-Switz.), 52
Construction industry
impact of climatic change, 58, 59
structures resistant to
earthquakes, 39
hurricanes, 136
tornados, 145
weather forecasting for, 101
Contaminants
environmental, 329-370
Great Lakes, 264
marine, 330, 357-363
see Pollution, Atmospheric;
Pollution, Water
Continental drift, 26, 32, Fig. II-4
Continental margins: sea floor discontinuity,
29, 31
Continental shelf: storm damage near,
28, 135
Continentality, 52, 64, 190
Continuity equation for air quality models,
335
Continuous culture theory: oceans, 233
Convection
earth's crust, 22
energy exchange for plants, 287
models, 47, 66, 67, 91, 140
precipitation stimulation, 173, 179
turbulence and, 108, 111
urban areas, llo, lio
water resources and, 200
weather, 96, 128, 186, 187
Cooling towers, 259
Coon, Carleton S., 373, 377
Copepods, Fig. VIII-5
m food chain, 237
Copper, 32, 272
Coral reef, 232
Coral Sea, 186
Cordillera Mountains, S.A., 31, 32
Coriolis force, 254, 258, 269
Corn
hybrid, 218
maize, 217
systems analysis of growing, 289
Corona of the sun, 3, 5
Corpus Christi Bay, Texas, 249
Costa Rica
gas deposits, 43
mud flows, 42
volcanic eruptions, 40
volcanic science, 44
Costs, see Benefit/cost analysis;
Economic effects
Cotton production
dependence on water supply, 204
pesticides and, 351, 355
Coulter, M. W., 228
Coulter method, 228
Council on Economic Growth, Technology
and Public Policy, Committee on
Institutional Cooperation (CIC), 269
Countryman, Clyde, 306
Cowan, J. Ritchie, 202
Cox, Charles S., 82
Coyote, 302, 304
Crater Lake, Ore., 40, 41
Crete, Greece, 44
Crossbills, 302
Crow, James F., 373
Crustaceans
trophic dynamics, 226, 228, Fig. VIII-2,
237, 252
petroleum lumps and, 363
Cryogenics: fog modification, 183
Cultural enrichment of bodies of water,
see Eutrophication
Currents
coastal, 128
lakes, 254, 255, 256, 270
lightning strokes, 161
ocean, 79, Fig. IV-2
tornadoes, 139
Cyanide: water contamination, 272
Cycles
air-sea, 84-88
antarctic ocean currents, 84
biospheric, 285
climatic change, 57, 59-61
definition, 60
diurnal and seasonal, 51
glacial/interglacial, 51
motions of the earth, 54
ocean surface temperatures, Fig. Ill— 2
stratospheric winds, 51
sunspots, 52
404
INDEX
Cyclones
cellars, 135
drought, lt>5
prediction, 91, 93, 94, 98, 144
synoptic systems and, 128
tropical, 184, Fig. VI-12
see also Tornadoes
Cystic fibrosis in European populations, 374
Cytogenetic studies of Yanomama Indians,
Fig. XI-1, Fig. XI-2
D region of ionosphere, 9, 10-11
Dakar, W. Africa, 194
Dallas, Texas, 140
Damage/destruction
by contaminants, 329
by forest fires, 207
by hailstorms, 151, Fig. V-12, 154
by hurricanes, 123, Fig. V-4, 128, 130,
133, 136, Fig. V-6
by lightning, 157, 160, 161
by solar energy, 8
by tornadoes, Fig. V-6, 144
by volcanoes, 42, 43, 44
by weather changes, 115
see also Disasters
Daphnia, 227, 228, Fig. VIII-2
Darwin, Charles
natural selection, 373, 374, 376, 377
sea floor contamination, 358
Data bases
adaptation to air pollution, 387
adaptation to drought, 219-220
air-quality criteria, 334, 340
climatic statistics, 120
cloud seeding technology, 171, 175
drought prediction, 167
ecosystem modeling, 282
estimates of water supply, 197
forest ecosystems, 300
animal ecology, 302
fire, 307
hurricane surveillance, 131
marine environments, 231
North Pacific Ocean, 242
Puget Sound, 249
measuring aeroallergens, 345
sea-air system, 78, 80, 82, 87-88
trophic dynamics of Great Lakes, 227
urban-affected weather changes, 114
water quality of Great Lakes, 264, 268
weather forecasting, 90-92, 93,
Fig. IV-7, Fig. IV-8, 98, 103
pilot reports, 106
tornadoes, 146
tropical areas, 188
Daubenmire, Rexford, 306
Davis, Margaret B., 73
Davis Sea, 232
DDD in lakes, 228
DDE in lakes, 228
DDT
in antarctic animals, 241
in birds, 351, 359
in fish, 228, 359
in lake waters, 272
in oceans, 233, 245
in pesticides, 352, Fig. X-13, Fig. X-14,
Fig. X-18
phytoplankton and, Fig. VIII— 3
temperatures and effects of, 57
use in forest areas, 207, 213
Deane, Margaret, 390
Death rates, 377, 378
air pollution and, 385
Deaths
Chagas' disease, 369
high altitude, 379
hurricane caused, 127, Fig. V-5, 136
lightning caused, 157, 158
tornado caused, 137, 138
Decay term for air pollutants, 336
Deciduous forests, see Forests
Decomposition in forest ecosystems, 292
Deer, White-tail, 302, 303, 305, 306, 310
Defense, U.S. Department of
air-sea system, 108
BOMEX support, Fig. VI-11
data networks, 23
volcano technology, 47
see also Air Force, U.S.; Armed Forces
Epidemiological Board, U.S.; Army,
U.S.; Army Medical Research and
Development Command, U.S.;
Cambridge Research Laboratories;
Naval Electronics Laboratory Center;
Navy, U.S.
Defoliation: effects on forests, 298
Deforestation
ecological effects. Fig. IX-9
effect on climatic changes, 55
Dendroclimatological studies, 59
Denmark, 386
Density of water in lakes, 254
Dental caries, 379
dePena, R. G„ 151, 152
Desalination of sea water for equatorial
areas, 187
Desert areas
arid America, 73-74
ecosystem model, Fig. IX-3
monsoons and, 184, 186
soil studies, 291
solar radiation in, 55, Fig. Ill 10
see also Arid regions
Dessens, J., 152-153
Detroit River, 263, 266
Developing nations
agriculture, 218
effects of parasitic disease, Fig. X-20, 369
polluting technology, 330
deVries, A. L„ 232
Diabetes, 379
Diablo Range, Cal., 29, 30
Diamonds, 22
deposits, 32
Diatoms, Fig. VIII-4
Dieldrin, 369
Diet, sec Nutrition
Diffusion
air quality, 334,335
lake waters, 256, 257, 259
tornado modeling, 140
water within forest canopy, 202
Dinoflagellates, Fig. VIII-4
Disasters
cactus growth in Australia, 297
marine monitoring, 231
Discover, USS (ship), 194
Diseases
airborne, 340, 341, 343
causation
contamination, 319-324, 327, 342,
343, 369
noise, 326
radiation, 325
environmental, 364-370
altitude-related, 379, 380, 383, 384, 385
genetic, 216, 373, 374
in animals, 217, 298, 303
in plants, 297, 300, 310
resistance to, 376, 378-379
smog and CO related, 385-390
see also Allergens, Airborne; Health; and
names of specific diseases
Diversion of water, 198, Fig. VII-1
Diving, 232, 233, 245
Djakarta, Indonesia, 86, Fig. IV-5
DOD, see Defense, U.S. Department of
Dolphins
toxicity in food chain, 363
tuna fishing and, 246
Douglas, J. W. B., 388
Douglas fir, 311
Drilling
continental, 21-25, Fig. II— 1, 30, 31, 57, 59
ocean, 53, Fig. Ill— 3, 55
Dropsondes: air quality measurement, 334
Drought, 165-168
adjustments to, Fig. VII-10
agriculture and, 218-221, 278
air-sea interactions, 86
definition, 166
tropical areas, 184, 188
Drug action: effects at high altitudes,
379, 384, 385
Dunbar, M. J., 231
Dust
Africa, 191-194, Fig. VI-13
effect on climate, 55, 56, 57-58, 59,
Fig. 111-10
nucleation centers, 329
pollution factor, 327, Fig. X-6, 343, 358
solar radiation and, 55, 67, 68, 71
Soviet economy and, Fig. X-15
tropical forests and, 298
see also Aerosols
Dust Bowl, Great Plains, 165
Dwarfism in crop yields, 216
Dynamo effect of earth's core, 24-25
Dynamo region of ionosphere, 10
Dzerdzeevskii, B. L., 72
E region of ionosphere, 9, 10
Earth
continental U.S., 28, 31
crust, 21, 27
shock wave, from solar wind, 5
sun's influence on, 3-17
see also Earthquakes; Volcanoes
405
INDEX
Earthquakes, 21, 22, 35-39, 135
effect on water quality, 212
locations, 26, Fig. II— 3, 28, 30
tidal waves, 81
volcanic eruptions and, 43
see also Seismicity of the earth
Earthworms, 292
East, Edmund, 218
East River, New York, 362
EASTROPAC Program, 87, 88
Echinoderms, 232
Eclogite, 29
Ecology, 21
climatic change and, 34, 72
definition, 285
precipitation management and, 173, 175
surveys, 231
see also Ecosystems
Economic effects
aquaculture, 250-253
climatic changes, 57, 59
Corpus Christi Bay, Fig. VIII-10
costs of contaminants in air, 332, 333, 338
fisheries of Puget Sound, 249
fog modification, Fig. VI-9, 183
hail-suppression, 151, 154
hurricane modification, 128
lightning-caused damage, 160
long-range weather forecasting, 97-98,
100
parasitic diseases, 367, 369
pesticides, 353
precipitation management, 172, 173, 175,
177
subsidence in oil and water
bearing formations, 203, 204
threat to tundra of developments, 313
tropical storms, 187-188, 189
turbulence, 108
urban-induced weather changes, 115
see also Benefit/cost analysis
Ecosystems
definition, 285
freshwater, 225-229
marine, 230-235
models, 209
studies of IBP, 58
terrestrial, 226
Eddy processes: ocean circulation, 80
Ekman, V. W., 79
Electrojets of ionosphere, 10
Electromagnet radiation
lightning, 157
tornadoes and, 138-139
urbanization and, 113
Electrons: concentration in ionosphere, 9
Elephant-seals, 240, 241
Emery, K., 361, 362
Emiliani, Cesare, 54
Emphysema: air pollution and, 319, 385,
Fig. XI-8, 387, 389, 390
Emulsifiers for floating oil, 362
Endrin: phytoplankton and, Fig. VIII— 3
Energy
hailstorms, 149
hurricanes, 124, 125
lightning, 157
monsoons, 186
needed for food production, 216
sun, 51, 52, 55
tornadoes, 145
volcanic explosions, 44
waste generation, 330
Energy budget
affected by urbanization, 116
clear air turbulence, 105, 106
cloud systems, 171
drought, 167
Great Lakes, 269
horse, Fig. IX-7
tropical areas, 187, 191, 194
water evaporation, 200
Energy transfer
ecosystems, 225, 285-291, 301
forests, 294, 300
tundra, Fig. IX-16
food chain, Fig. IX-6
leaves, 288
world oceans, 236, 237
England, 185,390
air-sea systems, 53, 56, 57, 69, 77, 87, 106
environmental contamination, 361, 390
human adaptation, 374, 386
severe storms, 149
urbanization, 113, 117, 119
weather forecasting, 100
weather modification, 181
see also London, Eng.
Environment
alteration by volcanoes, 44
definition, 60, 373
design, 272-280
management, 283, 298
impact of technology, 338
Environmental Protection Agency, U.5.,
(EPA), 330, 331, 337, 344, 390
Enzymes
high altitude adaptation, 382
plant growth and, 288
EPA, see Environmental Protection Agency,
U.S.
Equator
climate, 165, 166, 167
drift of pollutants across, 190
dry zones
meteorological observations, 187
magnetic, 10, 135
Pacific area
drought prediction, 168
Erie Canal, 261, 262
Erosion
after fire, 306, 308, 311
environmental management, 283
forests, 207, 208, 211, 214
tropical areas, 295, 296
lake aging, 268
precipitation augmentation, 177
steep slopes, 211, 212
surface water and, 204
Eskimos, 246, 376
Estuaries
ecosystem, 248-253
marine productivity, 235, 243
storm damage, 133
Ethology, Animal: application to humans,
376
Ethylene, 320
Eugeosynclinal belts of rock, 31
Euler, Ferdinand K., 26
Euphausia superba, see Krill
Euphausids, see Krill
Europe
agriculture, 291
air-sea system, 66, 86, 87
climatic change, 51, 52, 55, 57, 58, 68
data measurement, 59, Fig. IV-7
earth processes, 41
environmental contamination, 69, 193,
271, 343, 358
human adaptation, 374, 376
severe storms, 149
urbanization, 113, 114, 119, 226
Eutrophication, 209, 322
beneficial, 217
deforestation, Fig. IX-9
Great Lakes, 267-270
Lake Washington, 270-273
Evaporation
effect on water supply, 198, 200,
Fig. VII-2, 202
fog dispersal, 181
Lake Michigan, Fig. VIII-13, 259
Evapotranspiration, Fig. VII-1, Fig. VII-2
tropical forest, Fig. IX-10
Evolution, Cultural, 51, 377, 378
Exosphere, 11
Expendable Bathy-Thermographs (XBT), 87
Extreme ultra violet radiation, 4, 9, 10
F region of ionosphere, 9, 10
FAA, see Federal Aviation Administration,
U.S.
Farhi, Leon E., 389
Farming
aerobiology and, 343
climatic changes and, 57, 58, 59
cultural pest control, 354
hail damage, 154
marketing specialists, 250, 251
precipitation, 177
slash and burn technique, 296, Fig. XI-3
subsistence, 218
see also Agriculture
Faults, 30, 31
Fawbush, Ernest J., 101
Federal Aviation Administration, U.S.
(FAA), 158
Feedback
atmospheric temperatures, 56
causes of weather changes, 97
drought, 165
human ecosystem, 278
parasitic diseases and whole life of
affected individual, 367, 369
pest-control technology, 350
pollution control by nature, 330
models, 340
precipitation mechanisms, 170, 171
sea-air rythms, 86, 87
see also Interactions
406
INDEX
Fertility
human populations, 377, 378
high altitudes, 383
soil, 40, 45
tropics, 295, 296, 297
Fertilization of forest areas, 208, 209
Fertilizers
chemical, 278
human and farm sewage, 251
pollution effects, 323
runoff affecting water quality
Great Lakes, 265, 268
rivers, Fig. VIII-15
FIDO, see Fog Investigation and Disposal
Operation
Finches, 302
Finger Lakes, N. Y„ 262
Finley, J. P., 138
Fire
forest areas
effects, 207, Fig. VII-5, 212, 213
fire ecology, 306-312
Isle Royale, 304
lightning-caused, 157, 158, 160, 161
slash burning, 208
incineration
of wastes, Fig. X-2
spread of pollutants, Fig. X-16
Fish products, 239, 241
Fisher, R. A., 374
Fisheries
aquaculture, 250-253
climatic changes and, 57, 58, 79, 82
ocean data collecting, 87
distribution throughout world, Fig. VIII— 7
food sources, 217
world ocean, 236-247
lakes, 228, 254, 273
Great Lakes, 261-267
Lake Michigan, Fig. VIII-14
leisure activity, 293
management models, 234
ocean floor sediments and, 362
Puget Sound, 248-250
purse seine, Fig. VIII-9
species selection for aquaculture, 250
water flow to the oceans, 200
Fishes
adaptation to cold water, 232
effects of water pollution, 356, 359
in Great Lakes, 227
water quality required, 205, 206
see also names of specific species
Fletcher, C. M., 390
Floods
effect on water quality, 212
rain-caused, 128
tropical areas, 184, 296
Florida
agriculture, 252, 253
air-sea system, 79
climatic change, Fig. II— 7, 57
data measurement, 68
ecosystems, 307
environmental contamination, 191, 194
severe storms, 135, 147, 189
weather modification, 166, 171
Florida Power and Light Company, 252
Florida Straits, 79
Flounder, 253
Fluid dynamics
atmospheric circulation, 56
earth core studies, 22
lakes, 256
Fluid-flow instability in upper air:
models, 106
Fluorescence quenching, 331
Fluorides, 320, 322
Fluorometer, 256
Flushing rates of lakes, 266
Fly-ash: pollution by, 358
Fog, 180-183
industry-induced, 337
urban-induced, 113, 114, 117
Fog Investigation and Disposal Operation
(FIDO), 181
Food and Agriculture Organization, 299
Food chain, Fig. VIII-1, 234, 285, 286,
Fig. IX-6, 289, 301
Antarctic, Fig. VIII-6
aquaculture, Fig. VIII-11
in Puget Sound, 248, 250
in sea, 236, 244
pollution from DDT, Fig. X-14, 359
pollution from petroleum compounds, 363
pollution from toxic metals, 322, 323
Food pyramid, see Food chain
Food supply, World
contaminants, 322
protection from, 217
losses to, 339
diseases of plants, 341
production
fish, 228
potentials and problems, 215-218
world oceans, 233, 236, 237
projection, Fig. X-5
small number of crops and livestock,
217-218
sources
forested areas, 302
tropical areas, 298
Food web, see Food chain
Foraminifera, Planktonic, 53
Forest ecosystems, 292-301
animal ecology, 302-305
polluted precipitation and, 119
regeneration, 293, 297, 310
see also Fire
Forest Laboratory, U.S., Missoula, Mont.;
Riverside, Cal., 306
Forest management, Fig. VII-4, 205-212
land ownership, Fig. VII-4, 293
reforestation, 296
water quality and, 212-214
Puget Sound, 248
Forest Service, U.S.
fire ecology, 306
forest lands, 205
lightning research, 160
monitored ecosystems, 283
watershed research, 294
Forests
coniferous, 292, 308, 310, 337
deciduous, 295
comparison with rain forests, 299-301
serai stages, Fig. IX-1
fog benefits, 180
timber production, 292
tropical regions, 296, 297
fire and, 306, 307
trophic dynamics, 226
tropical, 292, 295-298
compared with temperate forests,
298-301
oxygen and, 34
rain forests, 295, 299-301, Fig. XI-3
Fort Tejon, Cal., 38
Fort Wayne, Ind., 114
Fossils
fuels, 68, 71
lake sediment, 344
mammals, 73-74
Founder effect, see Genetic drift
Fox, 304
France, 153, 154, 181, 183
Freeman, A. R„ 388
Freezing, Shock-induced: cloud seeding, 153
Freon
fog-seeding nucleant, 180
air pollution, 357
Frequency management in radio
communication, 14, 17
Fronts, Weather
turbulence, 105
urbanization and, 113
Fuels
toxic effects, 357-358, 360
see also Oil/Petroleum
Fuginaga, Motosako, 251
Fujita, T. T., 130, 145
Fumaroles, 43
Fungi
airborne, 340, 343, 345, 346
crop diseases, 341, Fig. X-8
fire and pine fungi, 306
in forest ecosystem, 292
G-6-PD deficiency, 365
Gaivoronskii, I. I., 151, 152
Game animals
disease resistance, 217
forests, 293, 302-303, 305
Gamma globulin in tropical populations, 378
Gamma rays, 33
Gannon, John E., 227
GARP, see Global Atmospheric Research
Program
Gary, Ind., 119
Gas chromatography, 331
Gases, 67, 329, 337
air pollution, 339, 340, 357
in clean, dry air, Fig. X-l
volcanoes, 40, 41, 43
Gasoline, see Oil/petroleum
Gauging stations of U.S. Geological
Survey, 197
Gaussian plume, 335, 336
Geiss, Johannes, 54
Genecology, 344
407
INDEX
Generators, Ground-based
for cloud seeding, 170, 175, 176
for fog-seeding, 180, 183
Genetic drift, 374, 383
Genetics
gene pool, 278
high altitude populations, 383
pest control, 352, 354, 367
plant breeding in tropics, 297, 300
Geological Survey, U.S., 29, 45, 46, 197
Geomagnetic tail, 7, 8, 10
Geomorphic changes by hurricanes,
133-136
Geophysical Fluid Dynamics Laboratory,
(NOAA), 66, 68, 82, 87
Georgia, 147
Geosphere, 301
Geosynchronous satellites
see Satellites, Geostationary
Geothermal heat, 33
German Atlantic Expedition, 187, 189
Germany
agriculture, 215, 241
climatic change, 57
severe storms, 154
urbanization, 119
Glaciation
atmospheric monitoring, 358, Fig. X-15,
360
boundaries, 52
causes, 52, 53, 54, 55
control of, 55
cycles, 62
ocean surface temperatures and, 53
volcanic activity and, 45
Global Atmospheric Research Program
(GARP)
data collection networks, 59, 88, 91, 95,
96, 97, 100, 101, 107, 126, 167, 190
monsoon forecasting, 184, 189
Global Network for Environmental
Monitoring (GNEM) 235, 344
Global techtonics, 21-33
earthquakes and, 26, Fig. II— 3,
28, 35, 36
"Globigerina ooze," 53
Clomar Challenger, D.V. (ship), 53, 55
Glover, Kenneth M., 106
Glowing avalanches: damage by, 42
GNEM, see Global Network for
Environmental Monitoring
Goiter, 378-379
Gold deposits, 32
Golden Gate Park, Cal., 117
Goldfish in Great Lakes, 263
Goldman, Charles R., 272
Goldsmith, John R., 390
Goose Creek, Tex., 203
Grand River, Mich., 270
Grand Traverse Bay, Mich., 269
Grape growing, 352
Graphite, 22
Grassland Biome Project, Colorado
(IBP), 344
Grassland ecosystem
fire ecology, 306, 307
model, Fig. IX-2
blue gramagrass, Fig. IX-4
temperate regions, 298
tropical regions, 296
Graupel, 150, Fig. VI-6
Grazing practices
effects of fire, 306
energy balance of a field, Fig. IX-7
environmental management, 283, 296
overgrazing
forest lands, 210, 214
tundra, 313
Great Lakes
circulation patterns, 82, 254-256
marine ecosystems, 225-228, 229, 230
pollution, 257, 259, 261-270, 272
Great Lakes Basin Commission, 268, 269
Great Lakes Deer Group, 303
Great Lakes Fishery Commission
(U.S. -Canada compact), 2o6
Great Lakes Fishery Laboratory,
U.S. Dept. of Interior, 266, 267
Great Plains, U.S.
cereal-rust epidemiology, 339
drought studies, 219
hail storms, 149, 154
tornado models, 147
Greece, 35
Green Bay, Wise: lake pollution, 257,
263, 269
Greenhouse effect
CO.- and, 82, 358
radiation balance of the earth, 70, 71
Greenland
climatic change, 52, 53, 54, 55, 57
data measurement, 360
ice cap, 330
Gregg, Ian, 386
Gregory, K. F., 344
GROSSVERSUCH III, Canton Ticino,
Switz., 152, 153
Groundwater levels, as part of water
supply, 197, 204
Grouse, Ruffed: survival, 302, 303
Guiana, S. A., 33
Gulf Coast
ocean systems, 81
severe storms, 133-135
Gulf of California, 33
Gulf of Mexico, 133, 135, 136, 147, 253
Gulf Stream, 78,79
Gunn, R„ 139
H
Habitat research, 303, 306, 310
Hailstorms
hailstones
formation and growth, Fig. V-ll, 151
modeling, 154
hailstreak, 152
modeling, 149, Fig. VI-6
cloud modeling, 154
predictions, 94
suppression and control, 147
experiments, 151-154
HAILSWATH, Project, 153
Harbors
pollution in, 223
debris in, 34
engineering models, 81
Hardwoods
and pine forests, 308, 309, 310
summer fires, 311
tropics, 296
Hardy, Kenneth R., 106, 109
Harrar, J. George, 339
Hawaii
earth processes, 27, 28
urbanization, 40, 41, 44
volcano technology, 35, 43, 45, 46
weather forecasting, 185
Hawaiian Volcano Observatory, 43, 45, 46
Hay fever, see Allergens, Airborne
Hazards
air pollution, 385, 386, 387
drought, 218
ocean pollution
food sources, 244, 245
pest controls, 351, 354, 355
to aviation, 108, 180
toxic wastes in near shore regions, 233
water quality in forest areas, 207, 209
see also Radiation hazards
Haze, 67, 68
air pollution, 192, Fig. X-6
assessed, 330-331
urban-induced, 117
Hazel, 311
Headfires, 310
Health
effects of air quality on, 334, 337, 338, 349
biological contaminants, 33"
see also Allergens, Airborne
effects of smog and CO, 385-390
high altitude living, 379-385
see also Diseases; Hazards
Heart diseases, 379, 380, 382, 384, 385
carbon monoxide and, Fig. XI-7, 390
Heat
antarctic waters, 84
distribution in the atmosphere, 105
lightning, 157
relation to food intake, Fig. IX-8
storm forecasting, 138
see also Pollution, Thermal; Thermal
bar; Thermal engine; Thermal plume
in lake water
Heat balance, see Solar radiation
Heat effects, 324
fog modification, 181, 182
tundra ecosystems, Fig. IX-16
urban areas, 113, 116, Fig. IV-12
Heat transfer
from earth's interior, 22
global circulation, 91
hurricanes, 125, 126, 128, 129, 131
ocean-air system, 78
Heathcote, John G„ 219
Hekla (volcano), Iceland, 41
Helicopters, 181
Helium, 10, 11, 51
Helmholtz, H. v., 109
Hemispheric interchange
atmospheric circulation, 188
Herbicides
forest areas, 205, 207
lake contamination, 272
2,4,5-T hazard, 351
408
INDEX
Herbivores, 74
balance of nature, 280, 285,286
forest ecology, 302-305
trophic dynamics, 225, 226
marine, 237, 239
see also Game animals; Livestock
Herculaneum (historic), 40
Heredity
adaptive traits, 383
high altitude, Fig. XI-4
Herring, 238, 363, 264
Heterozygosity, 373, 374
Hewlett, John D., 211
Hicks, Steacy D., 10"
High Altitude Hydrometeorological Service,
Nalchick, U.S.S.R., 151, 152
High Plains, U.S., 154, 204
Hilo, Hawaii, 41, 46
Himalaya Mts., 184, 186
HIRS (High Resolution Infrared
Radiometers), 69
Hoecker, W. H., 140
Holland, Joshua Z., 82
Holography: fisheries management, 244
Homozygosity, 373
Honolulu, Hawaii
modeling, 185
oceanographic cruises, 87
Hoof-and-mouth disease, 370
Hormone pesticides, 351
Horn, Ralph, 361, 362, 363
Horse: energy budget, Fig. IX-7
Houghton, Henry G., 183
Housing: disease control in Latin America,
370
Housing and household agents
polluting effects, 327, 385, 387
Hubbard Brook, N. H., 208, 293, Fig. IX-9
Hudson River, 262
Human factors
aggression, 376
air quality standards, 337
food chain, 225
forest ecosystems, 301
incidence of fires, 307
geomorphic coastal changes, 136
impact on environment, 223, 277, 334,
Fig. X-S
in climatic change, 58, 59, 63-64, 65,
67, 68, 69, 70-71, 101
in storm forecasting, 138
volunteer spotters, 147-148
in weather forecasting, 97, 99, 102,
104, 165
tropical areas, 185
labor in agriculture, 216
water quality, 211, 212, 213
water supply, 198, 218
see also Adaptation: human;
Pollution, Atmospheric: man-made
Humboldt Current, lo7
Humidity
cloud formation and, 165
fog modification, 181
forest fires, 306, 307
in atmosphere, 178
plant growth, 287, 288
prescribed burning, 310
tropical forests, 295
urbanization and, 113
water cycle, 200, 201, 202
Hungary, 33, 216
Humphrey, Robert R., 306
Hunt, James L., 201
Huntington Beech, Cal., 203
Hurricane Alix (1960), 134
Hurricane Audrey (1957), 134, 136
Hurricane Betsy (1965), 127
Hurricane Beulah (1967), 123, 124
Hurricane Camille (1969), 127, 133,
Fig. V-5, 136
Hurricane Carol (1954), 133, 135;
(1960), 134, 135
Hurricane Debby (1969), 126, 128, 129, 130
Hurricanes, 123-136, 191
effect on water quality, 212
forecasting, 94, 95, 98, 102, 103
models for, 91
modification
eye-wall seeding, 146
see also STORMFURY, Project
role in tropical weather, 188, 18"
Hutchinson, G. Evelyn, 254
Hutton, James P., 22
Hydrochloric acid: volcanoes, 43
Hydrofluoric acid: volcanoes, 43
Hydrogen, 10, 12
atomic
in thermosphere, 11
earth's mass, 51
fluoride, 342
ion activity, 212
sulfide
air pollution, 320
volcanoes, 43
Hydrologic cycle, Fig. VII-2
Hydrology, Stochastic, 197-198
Hydrosphere, 3
circulation in, 301
Hydrothermal pollutants, 321
Hygroscopic particles
seeding cold clouds, 175
seeding warm clouds, 174
seeding warm fog, 181, 182, 183
Hypoxia: in high altitudes,
381,382,384, 385
H.V.O., see Hawaiian Volcano Observatory
I
Ibadan, University of, Nigeria, 185
IBP, see International Biological Program,
U.S.
Ice
ages, 32, 120
cores
analysis, 58
atmospheric lead, 330
crystals
formation, 192, 193
precipitation formation, 174, 182
structure, Fig. VI-3
fogs (Alaska)
modification, 181, 182
tundra, 313
Ice-seals, 246
Iceland
air-sea system, 8o
climatic change, 52, 57, 72
earth processes, 27, 33, 41, 47
ICSU, see International Council of
Scientific Unions
Idaho, 29, 31
IDOE, set' International Decade of Ocean
Exploration
Igneous rocks, 30
IGY, see International Geophysical Year
Illinois, 31, 216, Fig. VIII-15
Illile
ice nuclei, 192
in ocean sediments, 358
Immunofluorescence
malaria diagnosis, 366
Imperial Valley, Cal., 33
Inbreeding, 374, 378
India
agriculture, 217, 218
earthquake prediction, 37
hailstorms, 149
monsoons, 184, 186
see also Institute of Tropical Meteorol-
ogy; National Council of Economic
Advisors
see also Rajasthan Desert
Indian Ocean
air-sea system, 78, 82, 84, 167
expedition, 82
severe storms, 134, 184
water resources, 236
Indians, American, 379, 384
Indonesia
aquaculture, 238
data measurement, 86
earth processes, 35, 40
monsoon forecasting, 184
urbanization, 43, 44
Indoor environments: aerobiology, 343
Industrial revolution, 113
Industry
effect on water quality, 199, 213, 214, 337
radiation damage, 323, 325
see also Pollution, Industrial;
Pollution, Thermal
Inertia: tornado modeling, 140
Infrared radiation
heat balance of the earth and, 287
spectrometry, 141
weather predicting, 103
Inland waterways, 82, 265
Insecticides
Chagas' disease, 369, 370
effect on terrestrial ecosystems, 301
forest areas, 207
malaria transmission and, 364-367
phytoplankton sensitivity to, Fig. VIII-3
Insects
air pollution, 339, 340, 341, 343, 345
pesticide resistance, Fig. X-ll
population model, 353
problem of agriculture, 216, 217
tropical plants, 297, 298
see also Malaria
Institute for Atmospheric Physics, National
Research Council, Italy, 153
409
INDEX
Institute of Marine Sciences, University of
Miami, 253
Institute of Tropical Meteorology,
Poona, India, 185
Instrumentation
animal ecology, 302
atmospheric circulation, 90, 334
balloon-borne, 90, 98, 190
climatology, 108
fisheries management, 244
forest ecosystems, 300
fire ecology, 307
hail research, 156
infrared thermometer, 256
ocean characteristics, 78, 80, 87
photomonitoring equipment for
antarctic waters, 233
physical limnology, 255, 256
severe storms, 95, 132, 147
tropical region studies, 188
urban effects on weather changes,
114, 115
weather modification, 170, 175, 176, 178
weather observations, 106
weather predictions, 103, 104
Insurance: hail damage, 154
Intelligence testing, 376
Interactions
air pollutants, 342, 343
atmosphere and its lower boundary,
89,91, 97, 101
crust and mantle, 21
fire studies, 307
Great Lakes
fish species, 264
man and fisheries, 263
heat balance of the earth and
photosynthesis, 287
host-parasite insects, 364,366
hurricane formation, 125, 126, 128, 131
insect species and pesticides, 352
lake water mixing, 254
internal waves and turbulence, 256
man and climate, 57, 115, 177
drought, 218
smog, 390
marine biological system and its
environment, 233
ocean-atmosphere, 77-88
contaminants, 359
rainfall, 165, 167
pollution control and economic
system, 334
Puget Sound, 248, 249
radioactive species, 358
sea floors and continental margins, 29
submodels developed separately, 282
temperate forests
animals and environment, 303
water-nutrient cycles, 294
tropics, 187
temperature and rainfall, 295
vegetation and environment, 301
vegetation and water cycle, 298
tundra ecosystems, 313, 314
waste disposal and conservation, 338
Interdisciplinary problems, see
Multidisciplinary problems
Interglacial periods, 53, 54, 55
Interior, U.S. Department of, Fig. VI-11,
266, 267
see also Great Lakes Fishery Laboratory
International Biological Program, U.S.,
(IBP)
aerobiology program, 339, 341, 342, 344
ecosystem studies, 58, 233, 279, 283, 289,
294, 300, 314, 344
human adaptation, 379, 380
International Council of Scientific Unions
(ICSU), 80
Global Atmospheric Research Program
(GARP), 91
International Union of Biological
Sciences, (IUBS), 344
International Union of Geological
Sciences (IUGS), 31
Inter-Union Commission on Solar-
Terrestrial Physics, 15
Scientific Committee on Ocean
Research, 80
International Decade of Ocean
Exploration (IDOE), 82, 88, 167
International Geophysical Year (IGY), 88,
190, 340
International Hydrological Decade, 294
International Hydrological Program,
International Field Study, 270
International Joint Commission
(Can.-U.S.), 267
International Reference Center on
Air Pollution (WHO), 388
International Union of Biological Sciences
see under International Council of
Scientific Unions
International Union of Geological Sciences
see under International Council of
Scientific Unions
Intertropic Convergence Zone, 194
Invertebrates: relationship of food and
heat, Fig. IX-8
Iodine, 118, 378
Ionization: created by radiation from
sun, 9
lonosondes, 15
Ionosphere, 3, 5, 8-11, 13-14, 17
electric field from earth, 158
storms, 10
Irazu (volcano), Costa Rica, 42, 43
Iribarne, J. V., 151, 152
IRIS (Infrared Interferometer
Spectrometer), 90
Iron, 35
content of dust over tropics, 193
deposits, 32
earth's core, 23
lake nutrient, 272
oxides, 295
Irrigation
health hazard, 217
in agriculture, Fig. VII-8, 220, 221
tropical regions, 296, 297, 298
water from Great Lakes region, 265
water use, Fig. VII-1, 204, 291
Isle Derniere, La., 135
Isle Royale ecosystem, 303-305
Isotopic studies
core samples, 55, 57
lead, 30
oxygen 180, 53
sea water, 84
strontium, 30
Italy, 153
earth processes, 33, 44, 53
human adaptation, 388
Ivory Coast, Africa, 192
Tagger, Thomas, 45
Japan
aquaculture, 238, 241, 242, 251, 252
earth processes, 30, 35, 37, 43, 44, 135
environmental contamination, 334,
Fig. X-12, 357, 363
human adaptation, 374, Fig. XI-2
oceanographic research, 240
weather prediction, 45, 100
Japanese Meteorological Agency, 81
Java, 41, 43,44
Jet streams
hailstorms, 149
heat distribution in the atmosphere, 105
low-level, 108
pollution transport, 357, 358
prediction of, 93, 94
subtropical, 86, 189
Jones, Donald, 218
Jones, H. L„ 139
Kailua-Kona, Hawaii, 44
Kamchatka Peninsula, Russia, 40
Kansas, 216
Kaolinite, 192, 358
Kapaho, Hawaii, 44
Kartsivadze, A. I., 151, 152
Kaskaskia River, 111., Fig. VIII-15
Kates, Allan H., 219
Keeling, Charles D., 330
Kelp, 240
Kelut Volcano, Java, 42, 43
Kelvin-Helmholtz waves, 109, 110, 111
Kelvin type waves, 255
Kenya, Fig. V-12
Kericho, Kenya, 153
Kilauea Volcano, Hawaii, 40, 43, 44, 45, 46
Kimura, Kazuo K., 374
Kinzer, G.D., 139
Kiska Volcano, Aleutians, 46
Kitumbe Estate, Kenya, 153
Kodiak, Alaska
polar ecosystems, 314
volcanic ash, 41
Komarek, Edwin Vaclav, 307
Koppen, Wladimir, 54
Krakatoa Volcano, Sumatra, 41, 44, 45
Krill
in food chain, 232, 237, Fig. VIII-6,
240, 241, 242
Kung, Ernest C, 105
Kuo, Hsiao-Lan, 82, 140
Kuroshio Current, 79, 244
Kutzbach, John E., 72
410
INDEX
La Jolla, Cal.: oceanographic cruises, 87
La Porte, Ind., 11°
Lactase deficiency, 376
Lahars, see Mudflows
Lake Erie
circulation patterns, 254
pollution, 262-268, 272, 273
urbanization, 226
Lake Huron, 262, 263, 265, 266, 267, 268
Lake Maracaibo, Venezuela, 203
Lake Michigan, 227, 228, 257, Fig. VIII-13,
259, Fig. VIII-14, 262, 263, 264, 265,
266, 267, 268, 270
Lake Ontario, 255, 261, 262, 263, 264, 265,
266, 267, 268, 270
Lake St. Clair, 263, 266
Lake Superior, 257, 262, 263, 264, 265, 266,
267, 268, 304
Lake Tahoe, 272
Lake Victoria, Africa, Fig. Ill— 1 , 52, 72, 220
Lake Washington, 270, Fig. VIII-16, 272,
Fig. VIII-17
Lakes, 294, 344
contaminants, Fig. X-14
dynamics of, 254-260
Laki (volcano), Iceland, 41
Lamb, H. H., 72
Land Grant College system, 218
Land surface: world total, 299
Land use
affected by climatic changes, 72, 73
arable areas and world population,
Fig. VII-8
droughts and, 167, 220
effects of changes in, 34
forest ecosystems, 294
urbanization and, 278
water quality and, 205, Fig. VII-7, 213
Landslides, 212
Langmuir, Irving, 154, 183
Langmuir spirals, 226
Larval ecology, 231
Lasers, 112, 194
Lassen Peak, Cal., 40
Latin America, 215, 370
Laurel forest, 298
Lava, 22, 27, 40-43
evidence of earth's magnetic field
reversals, Fig. II— 2
water storage, 203
Leaching of minerals
tropical forests, 295, 296
Lead
iodide (PbL), 118, 151, 152, 174
isotopic studies, 30
poisoning, 322, 327, 360
pollutants in the air, 320, 330
content of dust, 193
urban-produced, 118
toxic waste in lakes, 272
Legal implications
building codes
hurricane protection, 136
hurricane modification, 132
precipitation management, 173, 178
Leisure science, 280
see also Recreation and leisure time
Liberia, Fig. XI-3
Lichens: tundra, 313, 314
LIDAR (Light Detection and Ranging),
58, 112, 147, 194
Life support systems, see Food chain
Lightning, 157-161
light from, 157
research, 158-159
tornadoes and, 138
Likens, G. E„ 294
Lilly, D., 140
Limestone, 203
Limnology, 254
Great Lakes, 26"
Lake Washington, 273
List, R., 150, 151, 152
Lithosphere, 3, 29
Liverworts, 292
Livestock
effect on water quality, 210, 214
for western ranges, 74
horse energy budget, Fig. IX-7
protection against malaria, 367
see also Herbivores
Loblolly pine forests, 308, 310
Lodge, J. P., 330
Lominadze, V. P., 152
London, Eng., 53, 113, 117, 386, 390
Lone Pine, Cal., 38
Long Beach, Cal, Fig. VII-3
Lorenz, Edward Norton, 63, 120
Lorenz, Fred W., 376
Los Angeles, Cal.
air-quality models, 336
destructive earthquakes, 38
environmental contamination, 337, 388,
390
fog disposal operation, 181, 182
Louisiana
fire ecology, 308
severe storms, 133, 134, 135, 136, 147
Lozowski, E. P., 152
Lubbock, Texas, 204
Lubec, Maine, 135
Ludlam, F. H., 109
Lumbering and logging
water quality and, 210, 213
fire and, 308, 310
Lung disease and functioning
high altitudes, 381, 382
see also Pulmonary edema
Lunn, J. E., 388
Lynx, 304
Lysimeter studies, 209
M
Macdonald, Eleanor Josephine, 366
Machta, Lester, 64
McMurdo Sound, Antarctica, 232
Magma, 40, 43, 48
Magnetic field of the earth, 21
core and, 3, 23
earthquakes and changes in, 37
reversals, Fig. II— 2, 25, 27, 28
study of, 5
Magnetic fields: interplanetary, 4, 6
Magnetite-chalcopyrite, 31
Magnetopause, 3, 7
Magnetosheath, 3, 7
Magnetosphere, 3, 5, 6, 7-8, 9
Maine, 118
Malaria, 364-367
control and eradication of animal
diseases, 217
DDT and 352
resistance to, 376
see also Sickle cell anemia
Malaya, University of Kuala Lumpur, 185
Malaysia, 238
Mammals
extinct types, 73, 74
marine, 239, 240-241, 245, 247
Mammauthus columbi,
(extinct mammal), 73
Manabe, Syukuro, 64, 67, 69, 87
Manam Volcano, New Guinea, 43
Manganese deposits, 32
Manpower
air pollution research, 334
interdisciplinary training
environmental designs, 285
training
air-sea studies, 79, 82, 101
aquaculture, 251
pest control, 353, 356
malaria, 367
tropical meteorology, 185, 188
Mantle of the earth, 21, 23, 26-34
see also Earthquakes; Sea floor: spreading
Maps, climatic anomalies, 88
Mariculture, see Aquaculture
Marine invaders, Great Lakes, 262-263
Marketing specialists, see Farming
Marten, 304
Martinique, West Indies, 42, 44
Maryland, 308
Masaya (volcano), Nicaragua, 43
Massachusetts Institute of Technology, 183
Materials changes, due to stresses, 36
Mauna Loa (volcano), Hawaii, 41, 44, 46, 64
Mauritius Island, Indian Ocean, 134, 135
Measurements
aerobiology, 340, 345-349
air quality, 331, 333, 334
crustal velocity, 29
sea-air movements, 100
sound wave propagation, 112
windborne dust tranport, 191, 193
urbanization and weather changes, 115
Medical problems
high altitudes, 379-385
tropics, 364-370
see also Diseases
Mediterranean Sea
air-sea system, 86, 106, 109, 254
earth processes, 35, 44
Mendel, Gregor, 373
Merapi Volcano, Java, 42
Mercaptans, 320
Mercury, 272, 322, 357
Mesopause, 11
Mesosphere, 3, 11, 12
Mesozoic era, 29, 30, 31, 55
411
INDEX
Mesquite: fire and. Fig. IX-13
Metabolism
at high altitudes, 381
heart disease, 388-389
Metaldehyde, 174
Metallogenic maps for North America, 31
Metals: to\ic effects, 322, 357
see also specific names
Meteoric material in ionosphere, 10
Metropolitan Problems Advisory
Committee, Seattle, Wash., 271
Mexico, 74, 147, 358
Mexico City, Mexico, 204
Miami, Fla., 191, 194
University of, 253
Mice, see Rodents
Michigan, University of, 269
Microfossils, 344
Microminiaturization
equipment for weather research, 104
Micropaleontological analysis of
core samples, 53
Mid-Atlantic Ridge, 26, 27
Mid-Ocean Dynamics Experiment
(MODE), 80
Middle East, 280
Midwest (U.S.)
animal ecology, 303
atmospheric dust, 192
climatic change, 69
cyclone defense, 135
lake pollution, 271
Migration: marine mammals, 246
Milankovitch, M., 54
Milkfish, 251
Miller, Robert C, 101
Millet, 289
Minerals
forest soils, 296
mining, 214
prospecting, 28, 30-32
Mining of water, 204
Ministry of Agriculture and Forests,
Italy, 153
Minnesota, 302, 311
Minoan civilization, (Crete), 44
Mintz, Yale, 88
Mississippi Valley, 31, 38, 147
hurricanes, 133, Fig. V-5, 136
Missouri, 31, 38, 170
Mites: pesticide resistance, Fig. X-ll, 352
Mitochandria, 288
MODE, see Mid-Ocean Dynamics
Experiment
Models, Laboratory
lakes, 254, 269
lightning, 159, 160
tornadoes, 140, 141, 146
urban-induced weather change, 119
Models, Mathematical
air pollution, 334, 340, Fig. X-7, 335-336
antarctic marine life, 232
atmosphere-ocean systems, 58, 59, 64,
Fig. IiI-6, 68, 70
atmospheric circulation, 89-91
forest ecosystems, 293, 294, 295, 299,
300, 301, 307
animal-habitat relationships, 303
hailstorms, 149, 150, 154
heat-food relationships of invertebrates,
Fig. IX-8
lake circulation, 255, 269, 270
lightning behavior, 159
ocean currents, 79, 80, 81, 82-83, 87
pest control, 353, 366, 369
physical, economic and social
relationships, Fig. X-5
plant-energy exchange, 287, 288
tundra ecosystem, 314, Fig. IX-16
volcanic activity, 46, 47
weather modification, 174, 175, 176,
Fig. VI-6, 178, 181, 182
Models, Predictive
cloud seeding, 171, Fig. VI-3
drought, 167, 168, 220
for estimating water supply, 197, 198,
201, 202
for weather forecasting, 104, 114-115
dynamic-iterative, 96, 98, "9, 100, 106
statistical-physical-synoptic, 100
tropical meteorology, 185, 186, 187,
188, 189
hurricane, 95, 124, 125, 126, 128, 129,
131, 132
lake circulation, 254
solar activity and geophysical response,
16-17
tornado, 139, 140, 141
trophic dynamics of Puget Sound, 249
watershed research, 211
Models, Simulation
ecosystems, 281, 282
grassland, Fig. IX-2
mosquito submodel, Fig. IX-3
oceans, 233, 234, 235, 244
validation studies, 283, Fig. IX-4
Great Lakes, 269
upper atmosphere, 3, 14
volcanic processes, 46-47
watershed management, 211
Models, Submodels
ecosystems, 281, Fig. IX-3, 284
Mohorovicic discontinuity, 29
Mojave Desert, Cal, 29, 204
Molds
air pollution, 339, 343
crop diseases, Fig. X-8
Mollusks: aquaculture, Fig. VIII— 11
Molybdenum, 215
Monitoring
air pollution, 331
climatic changes, 51, 58, 68
ecosystems
forest fires, 307
model validating, 283, Fig. IX-4
for atmospheric contaminants, 337
Great Lakes water quality, 264, 266, 270
tornadoes, 138, 140-141
volcanoes, 44, 46, 48
weather stations, 137
Monocultures
domesticated plants and animals, 278
tropical regions, 297
Monsoons, 184-187, Fig. VI-10, 220
Montana, 31, 160, 306
Monte Nuovo (volcano), Italy, 43
Montmorillite, 192
Monzonite, 29
Moon, Fig. 1-3
Moose, 303-305
Moreno, Eudoro, 306
Morgan, B., 139
Morris, Dale Duane, 376
Mortality rates, see Death rates
Morton, Newton E., 373, 374
Mosquitos: submodel, Fig. IX-3, 364-367
Mosses
in forest ecosystem, 292
tundra, 313, 314
Motor vehicles: air pollution, 319, 385, 390
Mount Agung, Bali, 56, 68
Mount Baker (volcano), Wash., 44
Mount Katmai (volcano), Alaska, 41, 44
Mount Lassen (volcano), Cal., 40, 44
Mount Mazama (volcano), Ore., 40
Mount Pelee (volcano), Martinique,
42, 44, 45
Mount Ranier (volcano), Wash., 44
Mount St. Helens (volcano), Wash., 44
Mount San Salvatore, Switz., Fig. V-14
Mount Shasta (volcano), Cal., 44
Mount Wilson, Cal., 41
Mountain sickness, 382, 384, 385
Mountainous regions: clear air turbulence
over, 106
Mudflows, 207
volcanic, 42-43
Mueller, Peter Klaus, 388
Muller, H. J., 373
Multidisciplinary problems
environmental design, 279
Hubbard Brook Ecosystem Study, 293-295
human biology evolution, 378, 384
Museums, 231
Mussels, 241, 251
Mutations, 338, 373
Mysids, 238
N
Nairobi, University of, Kenya, 185
Namias, J., 166, 167
Naples, Italy, 43
NAS, see National Academy of Sciences,
U.S.
NASA, see National Aeronautics and
Space Administration
National Academy of Sciences, U.S.
(NAS), 91
see also National Committee for Clear
Air Turbulence
National Aeronautics and Space
Administration (NASA), 47, 69,
112, Fig. VI-11
National Bureau of Electrical Energy,
Italy, 153
National Center for Atmospheric Research
(NCAR)
BOMEX support, Fig. VI-11
environmental contamination, 330
modeling, Fig. Ill— 6, 66, 68, 235
National Committee for Clear Air
Turbulence, U.S., (NAS), 108
412
INDFX
National Council of Economic Advisors,
India, 217
National Hail Modification Program,
(NSF), 155
National Hail Research Experiment
(NHRE), (NSF), 151, 155, 156
National Hail Suppression Field Test,
(NSF), 153, 155
National Hurricane Center, (NOAA), 125
National Hurricane Research Laboratory,
(NOAA), 130
National Marine Fisheries Service,
(NMFS), (NOAA), 87, 253
National Maritime Commission, U.S., 189
National Meteorological Center,
Wash., D. C, 139
National Oceanic and Atmospheric
Administration (NOAA), 13, 16
modeling, 66, t>8, 81, 82, 87
project STORMFURY, 128
see also Geophysical Fluid Dynamics
Laboratory; National Hurricane Center;
National Hurricane Research Labora-
tory; National Marine Fisheries
Service; National Severe Storm
Forecast Center; National Severe
Storms Laboratory; National Weather
Service; Space Environment Laboratory
National Park Service, U.S., 304
National Science Foundation (NSF),
Fig. VI-11
see also National Hail Modification
Program; National Hail Research
Experiment; National Hail Suppression
Field Test
National Severe Storm Forecast Center,
(NOAA), 138
National Severe Storms Laboratory,
(NOAA), 138, Fig. V-8
National University, Taipei, Taiwan, 185
National Weather Service, (NOAA), 81,
Fig. IV-9, 102, 103, 136, 138, 141, 168,
171, 197
Natural enemies of pests, 350, 351, 352,
353, 354, 355, 356
Natural factors
in climatic change, 63, 64
contaminants, 329, 330
Natural gas, 33, 357
Natural selection, 72, 373-378, 383
pests and pesticides, Fig. X— 11, 354
Naval Electronics Laboratory Center,
San Diego, Cal., 109
Navy, U.S., 81, 102, 128
NCAR, see National Center for
Atmospheric Research
Negro, 376, 377
Nepal, 379
Nephelometer, 330
Netherlands, 339
Nevada, 29, 31, 204
New England
data measurement, 31
drought, 165
severe storms, 133
urbanization, 119
New Guinea, 43
New Hampshire, 293
New Jersey, 336
New Mexico, 31, 74, 204
New Orleans, La., 135
New York, 38, 53, 119, 336, 362
New Zealand, 33, 35, 44, Fig. VII-8
NHRE, see National Hail Research
Experiment
Niagara
falls, 262
river, 254, 255
Nicaragua, 43
Nickel sulfide ores, 31
Nigeria, 192
Nile River, 296
Nitrogen
as fertilizer
in agriculture, 215
in forest areas, 209
cycles, 282
enrichment of lake waters, 226, 228,
268, 272
Lake Washington, Fig. VIII-17
forests, 300
in soil of tropical forests, 295
in the air, 329
nitrogen oxides
air pollution, 320, 337, 388, 390
contaminants, 322
in groundwater, 200
in Lake Washington, 272
in rivers, Fig. VIII— 15
mesophere, 12
Nitrogen fixing
burned-over soils, 310
Nitrogen-fixing plants, 208
trophic dynamics, 227
NMFS, see National Marine Fisheries
Service, U.S.
NOAA, see National Oceanic and
Atmospheric Administration
Noise and vibrations: effects of exposure,
326
North America
air-sea system, 86
climatic change, 53, 55, 57, 73
drought, 167
earth processes, 30, 31, 35, 44
ecosystems, 286
pollution, 267
severe storms, 160
urbanization, 226
water resources, 291, 294
weather forecasting, Fig. IV-9, 115, 119
North Carolina, 309
North Sea, 33, 79, 81
Northern hemisphere
climatic change, Fig. Ill— 4, 61
monsoon winds, 184
temperature variation, Fig. Ill— 8,
Fig. III-9, Fig. 111-10
weather forecasting, 90, Fig. IV-7,
98, 101
Norway, 78, 241, 246
Norwegian Sea, 78, 102, 103, 104
NSF, see National Science Foundation
Nuclear reactors
effects on water quality, 231
estuaries, 248
lakes, 259, 268
oceans, 245
see also Heat; Power
Nucleating agents, 174
cloud seeding, 176
effect on hurricanes, 191, 193
fog dispersal, 180, 181, 182, 183
1,5-dehydroxynaphthalene, 174
see also Ice: crystals; Silver iodide
Nuclei
condensation, Fig. X-6
freezing, 117, 118, 174
hygroscopic, 153
ice, 153, 170, 171, Fig. VI-7, 181, 182, 193
precipitation, Fig. VI-2, 170, 329
see also Cloud seeding
Nuees ardentes, see Glowing avalanches
Nufioa Indians, Fig. XI-6
Nutrients
forest ecosystem, 292, Fig. IX-9, 295,
301,311
Great Lakes, 269, 270
Lake Washington, 271, 272
tundra ecosystem, Fig. IX-16
Nutrition
human, at high altitudes, 382, 383, 385
plant
crop production, 215
forest streams, 208, 209
phytoplankton, 234
requirements for aquaculture, 251
Nyamuragira Volcano, Africa, 44
Oasis effect: water cycle, 202
Observatories
for solar activities, 15, 17
seismographic stations, 23
Ocean-atmosphere system, 77-120, 287
BOMEX project, 125
drought prediction, 165
marine contamination in, 357-360
models, 65-72
monsoons, 186
phytoplankton and, 233
weather forecasting and, 101
Oceanography, 254
role in weather forecasting, 82, 100
Oceans
basins, 26
COj sink, 358
circulation, 77-88, Fig. IV-2, Fig. IV-3,
234
models, 68
currents, 78, 79, 83, 84
floor
Globigerina ooze, 53
oil on, 362
formation, 21, 24
heat sink, 257
source of carbon monoxide, 330
surface, 52, Fig. III-2, 58, 64, 100
thermal pollution, 34
tropical areas, 189
weather predicting over, 96
Ogallala Formation, 204
Ohio, 69
413
INDEX
Oil from marine animals, 240, 241, 242
Oil/petroleum
gasoline vaporization, 357
prospecting
Alaska, 32
continental shelves, 28
flow of wells, 47
worldwide, 31, 33
sea floor contamination, 361-363
subsidence of rock formations, 203
water pollution, 322
effect on marine mammals, 245
O'Keeffe, Andrew E., 330
Oklahoma, Fig. V-7
Olivine in mantle, 29
Omnivores: food chain, 286
Opik, Ernst, 52
Oregon, 40, 204
Organophosphorus compounds, 355
Orinoco River, SA., 300
Orographic clouds, 175
Orographic lifting and tilting, 111
Orville, H. D., 150
Ostracods, Fig. VIII-5
Ottersten, Hans, 106
Overgrazing, see Grazing practices
Owens Valley, Cal., 38
Owl monkey, 365
Owls, 302
Oxidation
carbon monoxide, 358
floating oil lumps, 362
of soil humus, releasing CO:.-, 71
Oxides, 319, 333
Oxygen
atomic
in mesosphere, 12
in thermosphere, 11
consumption by biosphere, 286
forest ecosystem, 301
from plants, 287, 288
human consumption at high altitudes,
379, Fig. XI-4, Fig. XI-5, 382
newborns, 384
in atmosphere 34, 320, 329
in forest streams, 206
in lakes, 263, 264, 268, 270
in Lake Washington, 271
in ocean water, 83, 84, 233
antarctic, 232
in the blood, 387
oxygen isotope (lsO)
ice-caps of Greenland, 57
in foraminiferal shells, 53
in sea-core dating, Fig. II 1—3
Oyster-farming: U.S., 252
Ozone (O:,), 11, 12
in atmosphere, 89, 319, 320
health hazard, 387, 388, 390
urban areas, 117
in stratosphere, 55, 58, 287
monitoring, 69
volcanic gases and, 41
P-waves, 29
Pacific Northwest, 209
Pacific Ocean
air-sea system, Fig. 1V-1, 78, 83-87, 165,
167, 358
coral reefs, 232
data measurements, 79, 81, 98, 100
earth processes, 28, 30, 31, 35, 37, 38, 45
environmental contamination, 367
severe storms, 123, 189
water resources, 233, 236, 242, 244
weather forecasting, 101, 168
PAHO, see Pan American Health
Organization
Paleozoic era, 31, 52
Pan American Boeing 707, 158
Pan American Health Organization
(PAHO), 379, 380
Panama City, Fla., 253
Panofsky, Hans A., 105
Paraffins, 361
Parameterization
cumulonimbus convection, 189
hurricane modeling, 126, 128
Parameters
animal ecology, 302, 304
ecosystem modeling, 282, 283
forests, 300, 301
hydrological
fisheries, 242, 249
ocean circulation, 234
physico-chemical, 340
Great Lakes, 227, 266
statistical
water cycle, 198, 201, 202
Parasites
in forest ecosystem, 292
malaria-spreading, 364, 365
world ocean mammals, 245
Paricutin Volcano, Mex., 41
Particulates
air pollutants, 319, 333, 337, 339, 385,
387, 388, 390
radionuclides, 340
see also Aerosols
Patagonia, S.A., 53
Pate, John B., 330
Patterson, Claire C, 330
Pauli, Hannes, 388
Pawnee site, 284
PCB (Polychlorinated biphenyls)
in fish, birds and mammals, Fig. X-16
in fish in lakes, 228
in oceans, 233, 359
Penguins, 232, 241
Penman, H. L., 201
Pennsylvania, Fig. VI-8, Fig. X-2
Perch, 261, 263
Perchloroethylene, 357
Peridotite in mantle, 29
Permutt, Solbert, 389
Persistence
adsorption of pollutants, 291
drought-producing systems, 165
forecasting, 99, 102
pesticides, 352, 356, Fig. X-16
water contamination in forest areas, 206
water currents in lakes, 255
Peru, 234, 379
Pesticides, 350-356
effect on food chain, 244, 245, 323
effect on terrestrial ecosystems, 301
effect on water quality
forest areas, 206, 207
Great Lakes, 264, 265
lake eutrophication, 268
pollution effects
chlorinated hydrocarbons, 320, 322,
333, 359
phosphorus, 321
2,4,5-T, 207, 213
see also Insecticides
Pests, 350-356
see also Insects; Pesticides
Petroleum, see Oil/petroleum
Petroleum hydrocarbons: marine
contaminants, Fig. X-17
Petrology, 46, 47
Pharmacological properties of tropical
trees, 298
Phenology of plant species, 289
Phenols, 322
Phenotypic selection in crop-breeding, 216
Phenoxy herbicide, 207
Philippine Islands
conservation, 251
earth processes, 35, 44
environmental contamination, 367
research facility, 185
Philippines, University of the, 185
Phlegrean Fields, Italy, 43
Phloroglucinol
cloud seeding nucleant, 174
fog seeding nucleant, 180
Phosphates
contaminants, 322
Lake Washington nutrient, 271
Phosphorus
enrichment of lake waters, 226, 228, 272
excess in Lake Erie, 264
forests, 296, 300
Great Lakes, 268
Lake Washington, Fig. VIII-17
Phosphorus-fixing
mineral soils, 209
trophic dynamics, 227
Photochemistry
air pollution, 385
ionosphere, 10
plant growth, 288
Photosynthesis
aquatic plants, 225, 226, 236
evolution of processes, 34
Lake Washington, 272
life support systems and, 285, 286
marine contaminants and, 359
modeling, 282
plant energy exchange, 287, 288
tundra ecosystem, Fig. IX-16
Phytogeography, 344
Phytoplankton, Fig. VIII-4
absorption of nutrients, 234
in aquaculture, Fig. VIII-11
in lakes, 226, 227
in oceans, 233, Fig. VIII-6, 359, 361, 362
sensitivity to insecticides, Fig. VIII— 3
Pike, Blue, 261, 263
414
Pine trees, 310, 311
air pollutants and, 337
Bristlecone, 61
Loblolly, 308, 310
Longleaf, 306
Shortleaf, 308
Piscivores, 227
Pitts, Grover C, 390
Planktivorous fish, 227, 228
Plankton, 53, 231, 340, 344
see also Phytoplankton; Zooplankton
Plant-water relationships, 219-220
Plants
aerobiology and, 343
antarctic, 313, 314
aquatic, 236
arctic, 314
diseases, 341, Fig. X-8
food chain, Fig. IX-6
food production, 216
growth, 288, 289
leaves, systems analysis, 289
spore reproduction, Fig. XI-1
Plasma physics, 3, 5, 8
Plasmapause, 8
Plate techtonics, see Global techtonics
Pleistocene era, 62, 73, 74
Pliocene age, 204
Plum Island, Mass., 133, 135
Polar bear, 377
Polar caps
absorption, 11, 14
magnetopause, 7
Polar front zone, 84
precipitation, 165
Polar regions
ecosystems, 313-315
effect of aerosols, 68
floating oil, 362
ice melting possibilities, 119
information lack on magnetopause over, 7
ionosphere and, 10
radio communication over, 11, 14-15, 17
shipping in, 82
soil studies, 291
see also Antarctica; Arctic regions
Polar wind: in F region of ionosphere, 10
Political considerations
air pollution control, Fig. X-4, 334
pesticides, 353
Point Barrow, Alaska, 313, 315
Pollen
aerobiology, Fig. X-7
air pollution, 339, 340, 343, 345-349
profiles
climatic change and, 59, 60, 61,
72, 73, 74
Pollinosis, see Allergens, Airborne
Pollution
programs, 232
projection, Fig. X-5
worldwide, 190
Pollution, Atmospheric
abatement by precipitation augmentation,
177, 178
biological, 339-349
chemical, 319, 320, 321, 327, 329-338, 357
pesticides, 354-356
effect on temperature, 194
forecasting of, 101
forests, 298
fire in, 213, 311, 312
Great Lakes area, 264, 268
hemispheric interchange of air, 188
lake eutrophication, 268
man-made
influence on climatic changes, 55, 57,
65, 66, 68, 69, 71, 72, 115
urban effects, 113, 116, 117, 118, 119
models
dispersion, 89, 96
weather forecasting, 93
natural causes
influence on climatic changes, 55, 69, 72
volcanoes, 21, 55, 56, 68, 71, 72, 329
nuclei for precipitation, 192, 193
radioactive elements, 33
regional controls, 332
smog, 385
turbulence and, 108
acoustic monitoring, 112
upper atmosphere, 65, 69
see also Carbon monoxide
Pollution, Chemical
estuaries, 248
Great Lakes, 264, 265, 268
pesticides, 354-356
Pollution, Industrial
atmosphere, 55, 357, 358
chemicals
Great Lakes, 264
from petroleum products, 248
lake eutrophication, 268
Pollution, Noise, 326, 327
Pollution, Radioactive, 33, 323, 325
Pollution, Soil, see Soils
Pollution, Thermal, 34, 199-200, 255,
Fig. VIII-12, 322, 337
coastal areas, 248
fish culture and, 252
lakes, 254
Great Lakes, 263, 264, 266, 268
Lake Michigan, 257-260, Fig. VIII-13
oceans, 245
Pollution, Water
abatement by precipitation augmentation,
177
antarctic, 241-242
coastal areas, Fig. VIII-7
enrichment of Great Lakes, 227, 228
forest areas, 206-207, 209, 312
lakes, 254, 257
sea farming and, 251
world ocean, 79, 82, 83, 244, 245,
Fig. VIII-8
see also Pollution, Thermal; Sewage
Polygons: arctic tundra, Fig. IX-15
Polygyny: population structure and, 378
Polymorphism, 373, 374
Pompano, 250
Pompeii, 40
Pond culture of fish, 217
Population density
arable land in relation to, Fig. VII-8
cause of pollution, 330, 350
effect on forest and, 293
control of numbei
environmental des
modification of earth'-.
soil fertility and, 40, 45
water use factors, 198
Porometer, 201
Porpoises, see Dolphins
Port Louis, Mauritius Isl., 135
Portales, Texas, 204
Potash, see Potassium
Potassium, 32, 215, 300
eutrophication in Great Lakes, 268
Power-generating plants
thermal water discharges, 199-200, 249,
254, 257, 325, 337
benefits for aqua farming, 252
Great Lakes, 263, 268
influence on Lake Michigan,
Fig. VIII-13
Prairies
solar radiation in, 55
climatic change, 73
Precambrian rocks, 30
Precession of the earth, 54
Precipitation
atmosphere-ocean system, 67, 360
biological particulates, Fig. X-6, 349
climatic records, 51, 58
dust removal by, 358
fluctuations, 57
forecasting, 100, 102
forest land, 205
in forest ecosystems, 294
indicated by tree rings, Fig. Ill— 5
models, 89, 95
modification, 169-179, Fig. VI-2
nucleation centers, 329
urbanization and, 113, 117, 118
pollution in, 119, 337
water cycle, 198, 200, Fig. VII-2
lake eutrophication, 268
world-wide, 165, Fig. VI-1
see also Rainfall; Snow
Precipitation stations
National Weather Service, 197
Predators
balance of nature, 280
control of, 303
in forest ecosystem, 292, 302
modeling, 282
see also Isle Royale ecosystem
Predictions
air turbulence, 111
change in shallow-water communities,
230-231
climatic changes, 59, 61
droughts, 165-168, 172, 221
earthquakes, 35, 36, 38
forest stream temperature, 206
injury to ecological systems, 340, 342
lead concentrations in ocean, 360
long-range effects on biosphere, 280
processes in forest ecosystems, 292-293
responses of ecosystems to changes, 300
responses within ecosystems, 289
sea-air rhythms, 78, 79, 80, 81, 89
solar activities, 5, 6, 11, 13, 16-17
volcanic eruptions, 43-45
415
INDEX
water supply, 197-202
weather, 94, 95, 97, 100
hurricanes, 123-124, Fig. V-3, 135, 136
severe weather, Fig. V-10
tornadoes, 137-138, 146
sec also Weather forecasting
President's Science Advisory Committee
(PSAC),215
Pressure
atmospheric
climatic records, 51, 58
cloud seeding, 129
ocean currents and, 78
sea level, model, Fig. III-6
sea temperature and, Fig. IV-5
tornadoes, 137, 144, 145
tropical regions, 188
weather, 95
effect on materials, 22, 23
subsidence, 203
Primates: malarial infection, 365
Primitive man, 74, 378
Princeton University, 87, 88
Propane, Liquified: fog-seeding nucleant,
180, 183
Protactinium-231, 53
Proteins
chemical changes in, 388
in marine animals, 239, 240-242
Prudhoe Bay, Alaska, 32
PSAC, see President's Science Advisory
Committee
Public Health Service, U.S., 365
Puerto Rico, 135
Puget Sound, 248, 249, 250, 270, 271
Pulmonary edema (HAPE), 379, 384, 385
Pumice, 362
Punta Arenas, Chile, 241
Purdue University, 304
Purse seine, Fig. VIII— 9
Pyroclastic material, 40
Quail, 306
Quartz
in dust over tropical areas, 193
in ocean sediments, 358
Quaternary volcanoes, 45, 63, 344
Quizapu (volcano), Chile, 41
Rabbits, 304, 388
"Race": human differences, 373, 374
376, 377, 378
Radar, Acoustic
ultra-high resolution, 108, Fig. IV-10
WIT detection, 112
Radar, Coherent laser, see LIDAR
Radar, Doppler, 95, 110, 140-141, 144, 147
Radar, Frequency modulated
continuous wave, 109, 110, 111
Radar, Incoherent scatter, 9-10
Radar, Pulsed microwave
cloud measurements, 170, 176
observations, 108
air-borne, 111, 129-130
ground-based, 111
hook-shaped echoes, Fig. V-7
weather modification, 178
storm detection, 94, 95
tropical areas, 187
weather prediction, 103, 104, 109, 138,
141, Fig. V-8, Fig. V-9, 147, Fig. V-10
Radiation belt, 6, 8
Radiation hazards
man in space, 5, 14, 25
effects, 325
Radio waves
commnications, 3, 4, 5, 8, 11, 14
lightning, 157
Radioactivity
dating techniques, 53, 54, Fig. III-3, 58, 72
fallout, 332, 340
wastes, 323, 335, 357
Radiometric sounders, 87, 90, 96, 98
Radiosondes, Fig. IV-6, Fig. IV-7, 98
Radon-222, 193, 194
Ragweed pollen, 345, Fig. X-9, 347,
Fig. X-10
Rainfall
air-sea rhythms and, 85-86
Canton Island, Fig. IV-4
areas of malaria potential, Fig. X-19
causes, 165
cloud seeding model, Fig. VI-6
for prescribed fire in forests, 310
generation, 170
hurricane carried, 126, 128, 131, 133
in ecosystems, Fig. IX-5
tropical forests, 295, 298, Fig. IX-11
lightning and, 160
tornadoes and, 139
tropical areas, 186, 187, 189
typhoons, 140
urban-induced, 115
see also Monsoons
Rajasthan Desert, India, 58
Ramage, Colin S., Fig. VI-10
RAND Corporation, The, 68
Rapid City, S. Dak., 153
Raschke, K., 202
Rawinsonde networks
tornado warnings, 146
weather analysis, 101, 104
Reaction rates
ocean layers, 89
precipitation mechanisms, 169
Recreation and leisure time
effect on water quality, 205, 209, 210, 214
factor in environmental design, 279, 280
forest wildlife, 303
game laws and aquaculture, 251
hunting, 293, 307
noise pollution, 326
tourism in arctic, 313
water use, 200, 254, 257
see also Aesthetics
Recycling of resources, 338
environmental design, 278
food chain, 226
Red crab, 240
Red scale, Fig. X-13
Redondo Beach, Cal., 203
Reducers: trophic dynamics, 225
Reflectivity of the earth,
see Albedo of the earth
Regional effects: urban-induced weather
change, 115, 119
Regional Meteorological Center,
Darwin, Australia, 185
Residence time
air pollutants
carbon monoxide, 358
water pollutants, 267
DDT, Fig. X-14
Great Lakes, 269
ocean-floating oil lumps, 362
oceans, 357
Resistance
children to disease, 378
pest species, 350
malarial insects, 364, 365, 367
Resources, Nonrenewable: projection,
Fig. X-5
Respiration
air pollution and, 385, 386, 387, 388
high altitudes, 381, 385
plants, 288
Revelle, Roger (R. D.), 82
Reynolds numbers, 269
Rh babies, 374
Rhodesia, 297
Ribeirao Preto, Brazil, 369
Rice production, 218, 220
Richardson, L. F., 107, 109, 110
Richardson number (Ri), 107, 109, 111
Richter scale, Fig. II— 7
Rio de Janeiro, Brazil, 41
Rio Grande River, 31
Rio Negro River, S.A., 300
Riometers, 15
Rivers
as a water supply, 187
impact on lakes, 270
nitrate concentrations in, Fig. VIII— 15
nutrient-rich, 268
thermal pollution, 34
Robbins, Robert Crowell, 330
Robinson, Elmer, 330
Robinson, George D., 68
Rockets
pollution, 65, 69
used in cloud seeding, 151, 152, 153
Rocketsonde programs: weather
forecasting, 101
Rocky Mountain Arsenal, Col., 39
Rocky Mountains
earth processes, 28, 29, 31
precipitation, 166, 204
severe storms, 160
weather forecasting, 38
weather modification, 177
Rodents
in food chain, Fig. IX-6, 302
malaria systems, 365, 366
rat middens, 73
Rosenthal, S. A., 128
Ross Sea, Antarctica, 84
Rossby, Stig A., 13, 102, 103
Rossow, V., 139
Rotation of the earth, see Coriolis force
Rotifers, 228
416
Royal Observatory, Hong Kong, 185
Royal Society, London, Eng., 51
Rubber, Fig. VII-9, 297
Rubidium in isotopic studies, 30
Russia, 68, 358, 359
fishing, 232, 241, 242, 24o
Moscow, 41, 53
oceans, 82, 239, 241, 244
soil, 220, 291
Ukraine, 216
volcanoes, 44
weather, 69, 100, 106
hail, 149, 151, 152, 154, 155
Rusts (plant diseases), Fig. VII-9,
339, 340, 341, Fig. X-8, 343
S-waves, 29
Saarinen, Thomas Frederick, 219
Saginaw Bay, 263
Sahara (desert), Africa, 52, 192, 193, 329
St. Lawrence River, 261, 262
St. Lawrence Seaway, 259
St. Louis, Mo., 113
St. Pierre, Martinique, 42, 44
St. Vincent (island), Lesser Antilles, 42
Salmon, 266, 271
Atlantic, 261, 262
coho, 228, 263
Salmonella, 217
Salt
cloud seeding, 174, 192, 329
deposits, 28
in blood of fish, 232
in haze, 68
in irrigation waters, 291
in ocean waters, 83, 84
Salton Sea, Cal., 33
Samoa, 87
Samplers, Aeroallergen
Durham, 347
impaction, Fig. X-10
rotoslide, 348
San Andreas Fault, Cal., 26, 30, 36, 37
San Bernardino Mountains, Cal., 337
San Diego, Cal., Fig. IV-10
San Francisco, Cal., 35, 38, 39, Fig. IV-12,
357
San Gabriel Mountains, Cal., 337
San Joaquin Valley, Cal., 204, 352
San Jose, Cal., 204
San Juan, Puerto Rico, 44
Sand, 135, 329
Sandstone, 203
Santa Barbara, Cal., Fig. VII-5, 361
Santa Clara Valley, Cal., 204
Sardines, 237, 238
Saskatchewan, Can., 32
Satellites
APT, 185
atmospheric circulation, 90, 96
cloud cover monitoring, 68-69
drag, 14
effect of radiation, 8
instrumentation, 87, 90, 96, 98
observations from, 5, 7, 15, 22, 97, 98, 104
radiation monitoring, 58, 59, 66
sea-air studies, 78, 81, 84, 87, 100
weather forecasting, 103
tropical areas, 187, 188, Fig. VI-12, 190
Satellites, Geostationary
ATS-3
atmospheric dust, 191, Fig. VI-13
hurricane surveillance, 129, 130, 134
storm tracking, 94, 95
weather forecasting, 101
Satellites, Polar orbiting
ESSA-3, 124
hurricane pictures, 95, 123, Fig. V— 1,
Fig. V-2
ITOS-I, 69
Nimbus-3, 90, 98
Nimbus-4, 69
Nimbus-F, 69
weather forecasting, 101
Sauger in Great Lakes, 263
Saury, 363
Savannah, Forest, 299
Scales
distance, Fig. X-3
time
air-sea systems, 79, 82, 83
atmospheric circulation, 91
models of the atmosphere, 90
Scandinavia, 86, 314
Schaefer, Vincent J., 154, 183
Schistosomiasis, 217, 323, 367-369
Scholander pressure chamber: soil profile,
202
Schove, D. J„ 51
Sculpin in Great Lakes, 263
Sea farming, sec Aquaculture
Sea floor
oil, 361-363
spreading, 22, 26-27, 29, 32
Sea lamprey in Great Lakes 262, 263,
264, 266
Sea levels, Interglacial, 54
Sea-lion, 241
Seals in sub-antarctic, 232, 240, 241,
242, 246, 247
Seas, see Oceans
Seattle, Wash., 53, Fig. VI-7, 270, 271
Seaweeds
as food source, 236
sub-antarctic, 232
Secchi disc, Fig. VIII-16
Sediment particles
effect of land use, Fig. VII-7
flow rate, Fairfax County, Fig. VII-6
microfossils in lakes, 344
ocean floor, 358, Fig. X-17
pollen proples, 61, 72, 73
water quality and, 206, 209
Seeding techniques for fog, 188-183
see also Cloud seeding
Seedlings, Hurricane: surveillance of, 123,
Fig. V-l, 125, 126
Seiches, 254, 255
Seismic measuring and monitoring, 28, 31
seismographs, 22
waves, 22, 28, 29
Seismicity of the earth, 35, Fig. II— 5, 37
U.S., Fig. II-7
Selenium, 215
Sellers, William D., 67
Semi-arid regions
water supply, 198
water conserving, 220
Semi-deciduous fores :
Severe local storms: prediction
Sewage
as fertilizer, 251
effect on aquatic life, 230, 231, 233-234,
235
effect on estuaries and coastal zones, 248
effect on lakes, 254, 265
Lake Washington, 270, 271, 272, 273
in aquaculture, Fig. VIII-11
in humid tropics, 300
pollution, 230, 323, Fig. X-16
oceans, 357, Fig. X-17
Shales, 203
Shallow-water communities
predictions of change, 230-231
seaweeds, 236
Sheepshead, 261, 263, 266
Shipping
hazards to, 33-34, 41, 82, 180
water use to maintain stream depth, 200
weather forecasting for, 81
Ships: used for sea-air studies, 78, 79, 84,
87, 100
Shock waves
solar wind, 5
seismic, 22, 35, 36, 38, 39
Shore zones
lakes, 254, 255
Great Lakes, 268
see also Coastal areas
Shorebirds: tundra ecosystem, Fig. IX-16
Showa Shin-Zan, Japan, 43
Shrimp
sergestid, 238
Japan, 251
aquaculture, 253
see also Krill
Shrimp-seals, 241
Shull, George, 218
Siberia, 189, 314
Sicily, 35
Sickle cell anemia
in Liberia, Fig. XI-3
malaria and, 365, 377
race and, 373, 374
Sierra Nevada Range (U.S.), 29
Signal Hill, Cal., 203
Silicic rock, 29
Silver bromide (AgBr) : cloud seeding,
Fig. VI-3
Silver iodide (Agl)
cloud seeding, 128, 129, 141, 175, 192
hailstorms, 151, 152, 153, 154
lightning reduction, 161
precipitation modification, 170, 172,
Fig. VI-3, Fig. VI-4
fog seeding, 180
Singapore, Fig. IV-5, 185, 238
SIRS (Satellite Infrared Spectrometer),
90, 98
Skillet Fork River, 111., Fig. VIII-15
Skin color in human populations, 374-375
417
INDEX
Slash-and-burn technique in tropical
agriculture, 296, Fig. XI-3
Smagorinsky, Joseph, 88
Smelt, 261, 263, 264
Smith, J. E„ 232
Smithsonian Institution, 47, 52
Smog, 12, 65, 67, 68, 113
adaptation to, 385-390
chambers, 334
photochemical, 335, 336, 385, 387, 390
ecology of, 337-338
Smokes, 65, 67, 68
air pollution, Fig. X-6
forest fires, 33
urban-induced, 113
Smut (plant diseases), 341 Fig. X-8, 343
Snails, see Schistosomiasis
Snake River Plain, 29
Snow
cloud seeding and, 170, 171, 177
cover
climate and, 64, 68, 97
satellite monitoring, 59
tundra, 313
urban areas, 114, 117
Social implications
air pollution control, Fig. X-4, 334
climatic changes, 57
man-induced weather changes, 172,
173, 175
parasitic diseases, 367, 369
pollution, 327
Social sciences: role in agricultural
adaptations, 220, 221
Sodium arsenate (herbicide), 213
Soils
fertility, 40, 45, 295, 296, 297
fire and microorganisms, 311, 312
in forest ecosystems, 292, 293
southern pine areas, 311, 312
tropical areas, 295, Fig. IX-10
leaching
irrigation, 216
water storage and, 202
pollution, 291, 323
reserves of plant nutrients, 215
studies for ecosystems, 291
water storage, 200, 202, 211, 212
Solar constant, 52, 55
Solar flares, Fig. 1-1, 5, 6, 13, 14
Solar radiation, 3, 52, 254, 287
absorption by animals, 289
atmosphere-ocean system, 66, 67, 70
atmospheric circulation and, 89
climatic changes and, 55, 64
ecosystems, 285, 287, 288, Fig. IX-9, 301
food chain, Fig. IX-6
effect of dust, 57-58, 68, 191, 194
effect of pollution, Fig. X-2, 332
effect of snow, 89
effect of volcanic activity, 45
effect on climate, 52, 65-69, Fig. III-7
tropical areas, 186
extreme ultraviolet, 4, 9, 10
modified by CO=, 337
plant energy, 287
precipitation, 167, 173
re-radiation, 70
scattering, 58, 89
trophic dynamics, 225, 226
urban effects on, 113, 114, 116, 119
water movement and, 200, 206
Solar-terrestrial system, 3-13
Solar wind, 3, 5, 6, 8, 15
Sole, English, 249
Solfatara Volcano, Italy, 43
Solvents, Dry-cleaning: air pollution, 357
Sonar: fisheries management, 244
Sonoran Desert, Ariz., 282
Sound waves, 112
South America
agriculture, 167, Fig. VII-8, 242
air-sea system, 77, 86
earth processes, 27, 28, 32, 35, 44, 59
ecosystems, 286, 291, 297, 300
environmental contamination, 364, 365,
370
human adaptation, 378
South Carolina, 309, 310
South Georgia Island, Antarctica, 239, 241
Southern hemisphere
chronology of tree rings, 61
dust measurements, 194
monsoons, 184
weather forecasting, 90, Fig. IV-7, 98, 103
Soybeans, 216, 217
Space Environment Laboratory
(NOAA), 16
Spain, 252
Spinel, 29
Spiny lobsters, 250
Sponges, 232
Spores: air pollution, 339, 340, 342,
343, 345
Sputum and cough, 386, 390
Squirrel, Gray, 302
Stabia (historic), 40
Stakman, E. C, 339
Standard of living, 330
Stanford Research Institute, Cal., 330
State, U.S., Department of, Fig. VI-11
Steam, Industrial: as pollutant, 329
Steering methods: weather prediction, 93,
94, 95, 148
Stokes, G. G., 192
Stokinger, H. E„ 389
Stommel, Henry Nelson, 79
Stone Age, 74
Stone-crabs, 241
Storm systems
climatic records, 51
droughts and, 165
tropical, 189
influence of dust, 191-194
modification, 187
turbulence in, 108
urbanization and, 113
see also Hurricanes; Severe local storms;
Tornadoes
STORMFURY, Project, 126, 127-132
Strait of Magellan, 241
Stratopause, 3, 11
Stratosphere, 3, 69, 287
drift of pollutants, 190
dust in, Fig. 111-10
turbulence in, 105
Streamflows
as part of water supply, 197, 198
stability of channels, Fig. VII-7
Stress measurement: earthquake prediction
and, 37, 38
Strontium, in isotopic studies, 30
Sturgeon, Great Lakes, 263
Sub-Antarctica
islands, 313-314
waters, 240, 241
Subsidence, in water and oil bearing
formations, 203-204, Fig. VII-3
Subtropical belt of dryness, le5, 166, 167,
191
Succession principle of natural communities
aquatic, 230
forests, 299, 304, 308
Suckers (fish), 261
Sukurajima (volcano), Japan, 45
Sulakvelidze, G. K., 152
Sulfur
agriculture, 215
sulfur oxides
air pollution, 319, 337, 360, 385, 387,
388, 390
modeling, 335, 336
natural causes, 330
smog, 337
urban areas, Fig. X-2, 319, 342
volcanoes, 21, 41, 43
sulphates
contaminants, 322
increase in Great Lakes, 268
Sumatra (island), Indonesia, 41, 44
Summer
anomalies, 56
droughts (U.S.), lob
dust transport, 191, 192
content, 193
forest fires, 309, 310
monsoons, 184
stratification of lake water, 258
urban effects on weather, 114, 116
Sun, 3-17
climate and, 51
damage to human beings, 325
heat input on Great Lakes, 257
radiation, 4, 14, 25
sunspots, 3, 4, 13, Fig III— 1, 52, 58
see also Solar radiation
Sunflowers, 216
Sunnyvale, Cal., 204
Superior Province, Great Lakes, 31
Surtsey (volcano), Iceland, 47
Sverdrup, H. U., 79
Switzerland, 154, Fig. V-14
Systematic biology, 231
Systems analysis
environmental design, 289, 340
forest ecosystem, 294, 295, 300
Great Lakes water management, 267, 269-
270
maintenance of the biosphere, 281
meteorology, 339
oceans and marine productivity, 233-235
pest control, 352, 353
plants, 289
418
Taiwan, 35
Talc, 359, 360
Tall Timber Research Station, Tallahassee,
Fla., 307
Tanganyika, 220
Tanzania, Fig. VII-10
Tarawa (island), 87
Taxonomic identification of plankton, 228,
230
Tay-Sachs disease, 374
Teal, John M., 3ol, 363
Teleconnections, 85, 88, 100
Telemetry
animal ecology, 302
energy relations of animals in the
ecosystem, 289
field studies of animals, 289
Temperate zone
agricultural practices, 295
drought, 165
forests, 292, 298-301
hurricanes, 123, 124, 135
Temperature
bacterial oxydation, 362
climatic records, 51, 52,
cloud-seeding, 176
cloud-top, 175
CO. content of atmosphere and, 64, 67,
Fig. Ill— 9, Fig. 111-10, 72, 332
deep earth processes, 22
derived from sea-core dating, Fig. Ill— 3
earth and above it, 89
historic records on, 58
human beings, 374, 376
northern hemisphere, Fig. Ill — 4, 57,
Fig. III-8, Fig. III-9, Fig. 111-10
nucleating agent effectiveness, 174
sounding by satellites, Fig. IV-6
worldwide effect of dust, 194
Temperature, Atmospheric, 11, 12
distribution, Fig. 1-5
effect of CO., 119
effect on clouds, 141, 174
effect on mosquitoes, Fig. IX-3
fluctuations, tropical vs. temperate
species, 298, Fig. IX-11
forecasting, 94, 100, 102
forest fires, 306, 307, 311, 312
formation of hailstones, Fig. V-ll
global variations, 55
in ecosystems, 285, Fig. IX-5, 300, 301
patterns, 102
plants, 287, 288, 289
Project STORMFURY, 129
records, 51, 52
smog, 337
tropical areas, 188
urban areas, 113, 114, 116, 119
Temperature, Water
Antarctica, 83, 231-232
Great Lakes, 261
lakes, 254
thermal influence, Fig. VIII-13
sea-surface, Fig. Ill— 2, Fig. IV-1
drought causes, 165
north Pacific, 78
tropical regions, 85, Fig. IV-5
water cycle, 200, 201, 202
forest areas, 206
Terrestrial ecosystems, 277-315
Tertiary era, 63, 358
Texas
earth processes, Fig. II-7
ecosystems, 306, 308
groundwater, 203, 204
range management, 74
severe storms, 123, 124, 140, 147, 154
Texas Agricultural Experiment Station, 204
Texas Tech University, Lubbock, Tex., 306
Thailand, 184, 185
aquaculture, 238
Thalassemia, 373
Thera (volcano), Crete, 44
Thermal bar
Great Lakes, 268, 270
lakes, 255, 258, 259
Thermal engine, 65-66, 67, 77, 123
Thermal plume in lake water, 259
Thermal pollution, see Pollution, Thermal
Thermocline, 84, 87
Thermohaline alterations, 83
Thermonuclear energy, 5, 8, 25
Thermosphere, 3, 11
Thomas, Heriberto V., 388
Thomson, J. J., 10
Thorium, 30, 53
Thorpe, Steven A., 106, 109
Thunderstorms
hailstorm type, 154, Fig. V-13
lightning and, 157, 160
prediction, 93, 94, 95, Fig. V-10
tornadoes and, 137, 138, 139, 144
tropical areas, 186, 187
Tibet, 184, 186
Tidal waves, 35
earthquakes and, 81
volcanic eruptions and, 44
Tides, 81, 123
atmospheric, 58
gauges, 87
sea-air system and, 78, 81
Time
factor in water cycle, 202
landscape stability, 211
Tin deposits, 32
TNT, 153
Tonga, Friendly Isls., Pac. Ocean, 35
Tornadoes, 137-148
effect on water quality, 212
hurricanes and, 123
occurrence, 132
predictions, 94, 98
Torrey Canyon, S.S. (ship), 361
Toxic substances
agriculture and, 278
changes in ecosystems, 280
Lake Washington, 272
see also Pollution, Chemical
Toyama, T., 388
Trace elements, 34, 296
Trade winds
dust from Africa, 191, 192, 193, 358
equatorial belt of wetness, 165
hurricanes and, 123
pesticides spread
precipitation
Transparency
decrease in Great L.i! i
measurements in Lai-. I
Fig. VII1-16, 272
Transpiration in plants, 287
Transportation
hazards due to fog, Fig. VI-8
impact of climatic change, 58, 59
Transportation, U.S. Department of,
Fig. VI-11
Transverse Ranges, Cal., 29
Tree rings: climatic change shown by, 58,
59-61, Fig. III-S
Trees, see Forests; Vegetation
Triggering agents
climatic events, 55, 69
convection, 119
earthquakes, 37, 39
gravity waves and turbulence, 106
precipitation, lead-contaminated, 118
waves, 111
waves and wind speed, 110
Trophic dynamics
aquaculture and, 252
estuaries, 248-253
Great Lakes, 225-229, 230, 261
world ocean, 236-247
Trophic levels
aquatic, Fig. VIII— 1, 226, 227, 228
estuaries, 248
Tropic of Cancer: atmospheric dust, 191
Tropical medicine, 364-370
Tropical regions
air-sea rhythms, 84-88
animal diseases, 217
atmospheric composition, 330
climatic changes, 57, 133
drought, 220
effects of dust, 191-194
human adaptation in, 378-379
natural air contaminants, 330, 344
radiative balance, 68
soil studies, 291, 295-297
storms
see Hurricanes; Typhoons
weather forecasting, 90, 91, 95, 98,
184-190
Tropopause, 105
Troposphere, 3, 11, 69
atmospheric circulation studies in, 90, 105
drift of pollutants, 190, 357
dust in, Fig. Ill 10, 193
tropical weather, 186
Trout
freshwater, 225, 251, 261, 262, 263, 266,
271
sea, 253
Trout, Dennis, 105
Trypanosomiasis, American, see Chagas'
disease
Tsetse fly, 344
Tsunamis, see Tidal waves
Tundra biomes, Fig. IX-15, 314, 315
Tungsten, 31, 90
Turbidity
atmosphere, 339
419
INDEX
measurement, 1°4, 331
monitoring, 56, 58
role of aerosols, 68, 71
urban-induced weather change, 119
forested watersheds, 206, 209, 210
Turbulence
earth's magnetic field, 6
forest canopy, 201
in atmosphere, 91, 335
urban-induced, 113
wave-induced, 105-112
in mesosphere, 12
lake waters, 254, 256, 260
tornadoes, 138
Turkey (country), 35
Turkey, Wild, 302, 306
Turner, J. S., 140
Typhoons
study of effects, 185
weather forecasting, 102
models, 91
u
Uccle, Belgium, 68
Udall, Kans., 139
Ukraine, 21o
Ultraviolet radiation, 55, 287
ionosphere, °, 11
urban areas, lip
United Nations: environmental research, 344
United States
agriculture, 199, 215, 218, 219, 291,
Fig. X-8
air-sea interaction, 56, 7}, 81, 89, 97, 106,
109
climatic change, 57, 08, 73, 74, 220
data networks, Fig. IV-7, 141, 147
drought, lo5, loc, 219
earth processes, 28, 29, 32, 45, 48
ecosystems, 205, 232, 233, 241, 24c, 251-
253, 261, 293, 295, 300, 302, 30t>, 308
environmental contamination, 69, 192,
194, 329-332, 334, 343, 345, Fig. X-9,
Fig. X-12, 367, 369, 390
human adaptation, 373, 374, 378, 379,
Fig. XI-6
pollution, 265-268, 270
regional weather, 185, 188
severe storms, 123, 126-128, 130, 133, 135,
137-139, 146, 149, 151, 153-155, 157,
158
urbanization, 113, 114, 118, 119, 283
volcanoes, Fig. II— 8
water resources, 210, 361
weather forecasting, 35-40, 42, 44, 94, 100,
103, 104, 181
weather modification, 170, 172, 181-183
Updrafts, 149, 150
Upper Colorado Pilot Project, 172
Upwelling
coastal, 80, 86
lake water, 255, Fig. VIII-12, 259, 269
Uranium, 30, 32, 325
Urban areas
aircraft pollution, 65
atmospheric chemistry, 336
biological pollution, 342, 343
ecology of smog, 337
hurricane damage, 135
ice nuclei, Fig. VI-7
solar radiation in, 55
Urbanization
air pollution-smog, 385
effects on large lakes, 22o
effects on water supply, 198
effects on weather, 114, 115, 118
environmental design requirements, 278
humid tropics, effect on ecology, 300
sea farming and, 251
spread of parasitic disease, 369
water quality and, 261
weather changes and, 113-120, Fig. IV-11
Urea
cloud-seeding nucleant, 174
fog-seeding nucleant, 180
Ury, Hans K„ 388
USGS, see Geological Survey, U.S.
Utah
groundwater, 204
seismic refraction profile, 29, 31
Valley of Ten Thousand Smokes, Alaska,
42, 44
Vegetation
affected by smog, 337
carbon dioxide removed from air, 358
effect on aeroallergens, 349
effect on water movement, 200, 201, 202
effect on water quality, 212, 265
fire and, 306
forested areas, 302
fossil studies, 73
pollen profiles and, 61
restoration upon lava flows, 41
sulfur dioxide removal from air, 330
urban areas, 118
western America, 74
see also Plants
VELA program, 23
Venezuela, 33, 203
environmental disease, 369
genetic differences, 374, Fig. XI-1,
Fig. XI-2
Ventilation: water movement and storage,
200, 202
Ventura-Winnemucca earthquake zone
(Cal. and Nev.), 31
Verification systems: weather forecasts, 102,
103
Veronis, George, 82
Vesuvius (volcano), Italy, 40, 43, 45
Vigo, Bay of, Spain, 251
Virginia
effects of hurricanes, 133
Fairfax County, Fig. VII-6
urban-induced weather change, 118
Viruses, Fig. X-6, 341, Fig. X-8
Visibility: urbanization and, 113, 117
Vital statistics: high altitude populations,
385
Volcanoes, 21, 40-48
carbon gases, 43
effects on water quality, 212
forest soil, 295
records on, 58
sea floor topography, 27-28
sec also, Ash, Volcanic
Von Neumann, John, 97
Vonnegut, B., 139, 183
w
Waite, P. J., 139
Walker's "southern oscillation", Fig. IV-5
Waller, H. J., 388
Walleye, 261, 263
Wallihan, Ellis F., 201
Wallops Island, Va., 10<>
Walter Reed Army Institute for Research,
3c5
Ward, N. B., 140
Warm fog, 181, 183
Warning systems
ecological changes, 344
ecological damage, 340
hurricanes, 136
tornadoes, 138, 144, 148
Wasatch Range, U.S., 31
Washington
crustal velocity, 29
fishery technology, 252
urban-related precipitation, 113, 119
volcanoes, 31, 40, 44
weather modification, 101
see also Seattle
Washington, D. C, 68, 98, 185
Washington, University of, 330
Forest Service, 306
Waste management
conservation and, 338
detinition of wastes, 330
forestry and, 213, 301
human ecosystem, 278
land pollution, 248, 323
rivers and, Fig. X-2
Water
contamination, 329
hurricane clouds, 129
volcanic action and, 42, 43
Water budget
cloud systems, 171
Great Lakes, 269
Lake Washington, 273
precipitation augmentation, 177
urban areas, llo
Water conservation devices, 296
Water management
development schemes and parasitic
diseases, 369
Great Lakes, 266, 267
Water quality
arid regions, 291
diverted use, 198
environmental design and, 278
forest areas, 205-214
Great Lakes, 2ol-270
lakes, 226, 227, 230, 257
standards, 214
Water resources, 197-204
Water shortages, 178
priorities, Great Lakes, 270
Water supply
agriculture, 215-216
420
contaminants, 322
data bases, 197
desert areas, Fig. IX-3, 291
for tundra vegetation, 313, Fig. IX-16
forest land, 205, 292, 300, 307
tropics, Fig. IX-10
storage in rocks, 203
tropical areas, 187, 188
Water use, 198, l°o-200
Water vapor
as pollutant, 337
disease carrier, Fig. X-21
atmosphere-ocean system, 66, t>7, 71
hail clouds, 152
heat balance of the earth and, 287, 288
hurricanes, 131
in clouds, 331, 337
in pure air, 329
precipitation, Fig. VI-2
storm forecasting, 138
tornado models, 139
urban area weather, 119
Watersheds
forest areas, 20e, 209, 211, 212
lakes, 273
northern hardwood, 293-295
Waterspouts, 144, 147
Waves
data, 78, 80
hurricanes, 127, 128
induced turbulence, 108-112, Fig. IV-10
kinds
gravity, 106, 111
Kelvin-Helmholtz, 109, 110, 111
Kelvin type, 255
lakes, 254, 255, 256, 259
models, 81
ocean-surface, Fig. IV-2
Weasels
in food chain, Fig. IX-6
tundra ecosystem, Fig. IX-16
Weather, 62
prescribed tire and, 311
urban-induced change, 119
see also Radar
Weather forecasting, Fig. IV-9
anomalies, 87, 88
climatology, 103
data base, 90-92, 93, Fig. IV-7, Fig. IV-8,
98, 103
extrapolation method, 93, 94, 95, 97
for fishing industry, Fig. VIII— 7
models, 93, 94, 95, 96, 97, 102
extended periods, 99, 105
role of oceanography, 82, 100
short-range, 94-96, 101-104
tropical areas, 184, 189
storms and hurricanes, 187
urban-induced changes, 114, 115
Weather modification
at airfields, 101
environmental management, 283
hail, 151
hurricanes, 126
lightning, 158, 190-161
tornado windspeed, 145, 146
urban-induced, 113-120, Fig. IV-11
see also Climate: control; Precipitation:
modification
Weather stations, 137, 138, 146
Weatherald, Richard T., 67, t>9
Weddell Sea, Antarctica, 84, 232
Weddell Seal, 232
Wegener, Alfred E., Fig. II-4
Well drilling, 203
Welland Canal, 261, 2c2
Weller, N., 139
Wells, Philip V., 73
West Germany, 181
West Indies, Lesser Antilles, 42, 134
West Virginia, 133
Western hemisphere
dust from Africa and, 191
model of sea-level pressure, Fig. III-6
Whales, 232, 241
in food chain, Fig. VIII-6
management of stocks, 245-24o
source of food, 240, 242
Wheat, 216, 217, 220, 289
White Mountains, Cal., el
White Mountains, N.H., 293
Whitefish
food fish, 227
Great Lakes, 261, 262, 263, 264
Lake Washington, 271
WHITETOP, Project, 170, 171, 172
WHO, see World Health Organization
Wilderness reserves
see Isle Royale ecosystem
Williams, Roger J., 376
Wilmington, Cal., 203
Wind
distribution
in tornado vortices, 138
tornado models, 139
flow patterns
atmospheric pollutants and, 335, 336,
344, 360
climatic change and, 56, 100
drought, 165
fog dispersal operations, 180
forecasting, 102, 104
hailstorms, 149
models, 89, 95
monsoons, 184
sea-surfaces and, 78, 86
severe storms, 125, 129, 130, 135, 138
tropical areas, 188
urbanization and, 113, 114, 116
water circulation, 254, Fig. VIII-12
weather modification systems, 174
shear, turbulence and, 108
speed
atmospheric pollution, 347, Fig. X-10
climatic records, 51
cloud seeding, 176
factor in plant growl: :.
forest fires, 306, 310
hailstorms, 149, 150, Fig. V-13
hurricanes, 123, 127-128
tornadoes, 137, 144-145, 14o
tunnels
air pollution research, 334
hail, 150
Wind River Basin, Wyo., 31
Winter
dust transport, 191, 192, 193
forest fires, 310
monsoon winds, 184
temperatures, 56, 57, 114
Wisconsin, 257, 2o3, 269
Wisconsin, University of, 269
WIT (wave induced turbulence), 108, 109,
110, 111, 112
WMO, sec World Meteorological
Organization
Wolf, Timber, 302, 304-305
Woods, J. D., 106, 109
Woods Hole Oceanographic Institution,
Mass., 3e>l
Work capacity, at high altitudes, Fig. XI-4,
Fig XI-5, 382
World Data Centers (Wash., D. C; Moscow,
U.S.S.R., etc.) : space data
clearinghouse, 15
World Health Organization (WHO), 379,
380, 385, 388
World Meteorological Organization
(WMO), 91, 100, 185, 188, 340
see also Commission for Climatology
World Weather Program (WWP), 91
World Weather Watch (WWW), 59, 91,
Fig. IV-7, 100, 101, 190
Wright, Sewall, 374
WWP, see World Weather Program
WWW, sec World Weather Watch
Wyoming, 29, 31
XBT, see Expendable Bathy-Thermographs
X-rays, 4, 9, 10, 11, 15
effects on humans, 325
fluctuations, 55
Yanomama Indians, Brazil, 374, Fig. XI-1,
Fig. XI-2, 378, 379
Young's modulus, 203
Young, Thomas, 203
Zinc, 193
Zooplankton, Fig. VIII— 5
in food chain, 234, 237, 240
in lakes, 227, 228, Fig. VIII-2, 262
421
CONTRIBUTORS
The following list is composed of (1) the names of people who
responded in writing to a request for information in an area of their
special interest and (2) the names of those people who contributed
illustrative material for use in the report. In some cases, individuals
contributed both text material and illustrations.
WILLIAM C. ACKERMANN, Illinois State Water
Survey
CLIFFORD AHLGREN, Quetico-Superior Wilderness
Research Station
DURWARD L. ALLEN, Purdue University
DAYTON L. ALVERSON, National Oceanic and
Atmospheric Administration
DAVID ATLAS, National Center for Atmospheric
Research
PAUL T. BAKER, The Pennsylvania State University
ROGER G. BARRY, University of Colorado
PAUL C. BEAVER, Tulane Medical Center
W. BOYNTON BECKWITH, United Air Lines
WILLIAM S. BENNINGHOFF, University of Michigan
JACOB BJERKNES, University of California at Los
Angeles
F. HERBERT BORMANN, Yale University
DUNCAN C. BLANCHARD, State University
of New York at Albany
ROSCOE R. BRAHAM, JR., The University of Chicago
WALLACE S. BROECKER, Lamont-Doherty Geological
Observatory
JOHN L. BROOKS, National Science Foundation
LINCOLN P. BROWER, Amherst College
KIRK BRYAN, National Oceanic and Atmospheric
Administration
REID A. BRYSON, The University of Wisconsin at
Madison
SIR EDWARD C. BULLARD, University of Cambridge
T. C. BYERLY, U.S. Department of Agriculture
TOBY N. CARLSON, National Oceanic and
Atmospheric Administration
DAVID C. CHANDLER, University of Michigan
STANLEY A. CHANGNON, JR., Illinois State Water
Survey
GABRIEL CSANADY, University of Waterloo
ALLAN C. DeLACY, University of Washington
ROBERT E. DILS, Colorado State University
HANS DOLEZALEK, Office of Naval Research
WILBUR G. DOWNS, The Rockefeller Foundation
RICHARD C. DUGDALE, University of Washington
JOHN A. DUTTON, The Pennsylvania State University
W. THOMAS EDMONDSON, University of
Washington
KENNETH O. EMERY, Woods Hole Oceanographic
Institution
CESARE EMILIANI, University of Miami
ROBERT D. FLETCHER, Department of the
Air Force (Retired)
THEODORE T. FUJITA, The University of Chicago
NORIHIKO FUKUTA, University of Denver
DONALD FUQUAY, Forest Service, Missoula
DAVID M. GATES, University of Michigan
R. CECIL GENTRY, National Oceanic and Atmospheric
Administration
STANLEY P. GESSEL, University of Washington
JAMES GILLULY, Geological Survey (Retired)
RAYMOND M. GILMORE, Natural History Museum
at San Diego
EDWARD D. GOLDBERG, Scripps Institution of
Oceanography
JOHN R. GOLDSMITH, Department of Public Health,
State of California
FRANK B. GOLLEY, University of Georgia
DAVID R. GOODALL, Utah State University
ARNOLD L. GORDON, Lamont-Doherty Geological
Observatory
LEWIS O. GRANT, Colorado State University
WILLIAM E. GORDON, Rice University
ROBERT F. GROVER, University of Colorado Medical
Center
JOEL W. HEDGPETH, Oregon State University at
Newport
CHARLES L. HOSLER, The Pennsylvania State
University
HENRY G. HOUGHTON, Massachusetts Institute of
Technology (Retired)
CARL B. HUFFAKER, University of California at
Berkeley
ROBERT R. HUMPHREY, The University of Arizon
PATRICK M. HURLEY, Massachusetts Institute c
Technology
EDWIN 5. IVERSON, University of Miami
CLA'i TON E. JENSEN, National Oceanic and
Atmospheric Administration
PHILIP L. JOHNSON, National Science Foundation
RALPH G. JOHNSON, The University of Chicago
ARCHIE M. KAHAN, Bureau of Reclamation
HIROSHI KASAHARA, Food and Agriculture
Organization
ROBERT W. KATES, Clark University
WILLIAM W. KELLOGG, National Center for
Atmospheric Research
GEORGE C. KENNEDY, University of California at
Los Angeles
EDWIN KESSLER, National Oceanic and Atmospheric
Administration
J. E. KIRBY, JR., Esso Eastern, Inc.
JOHN A. KNAUSS, University of Rhode Island
LEON KNOPOFF, University of California at Los
Angeles
EDWIN V. KOMAREK, Tall Timbers Research Station
HELMUT E. LANDSBERG, University of Maryland
NOEL E. LaSEUR, The Florida State University
EDWARD R. LEMON, Agricultural Research Service
and Cornell University
HELMUT H. LE1TH, The University of North Carolina
at Chapel Hill
GENE E. LIKENS, Cornell University
RAY K. LINSLEY, Stanford University
C. GORDON LITTLE, National Oceanic and
Atmospheric Administration
FRANK B. LIVINGSTONE, The University of
Michigan
JAMES P. LODGE, National Center for Atmospheric
Research
EDWARD N. LORENZ, Massachusetts Institute of
Technology
JOHN LYMAN, The University of North Carolina at
Chapel Hill
GORDON A. MACDONALD, University of Hawaii
BASSETT MAGUIRE, JR., The University of Texas at
Austin
PAUL S. MARTIN, The University of Arizona
THOMAS R. McGETCHIN, Massachusetts Institute of
Technology
CARL E. McTLWAIN, University of California at
San Diego
WILLIAM G. MELSON, Smithsonian Institution
HENRY W. MENARD, Scripps Institution of
Oceanography
RICHARD S. MILLER, Yale University
J. MURRAY MITCHELL, JR., National Oceanic and
Atmospheric Administration
CLIFFORD H. MORTIMER, The University of
Wisconsin at Milwaukee
WALTER H. MUNK, University of California at
San Diego
GARTH I. MURPHY, University of Hawaii
IEROME NAMIAS, Scripps Institution of Oceanography
JAMES V. NEEL, The University of Michigan
MORRIS NEIBURGER, University of California at
Los Angeles
JACK E. OLIVER, Cornell University
LOUIS J. OLIVIER, World Health Organization
HARRY ORVILLE, South Dakota School of Mines and
Technology
RICHARD E. ORVILLE, State University of New York
at Albany
LOUIS C. PAKISER, JR., Geological Survey
EUGENE N. PARKER, The University of Chicago
WILLIAM G. PEARCY, Oregon State University
ALLEN D. PEARSON, National Oceanic and
Atmospheric Administration
SVERRE PETTERSSEN, London, England
GEORGE W. PLATZMAN, The University of Chicago
JOSEPH F. POLAND, Geological Survey
ROBIN D. POWELL, Veterans Administration
JOSEPH M. PROSPERO, University of Miami
COLIN S. RAMAGE, University of Hawaii
GILBERT S. RAYNOR, Brookhaven National
Laboratory
RICHARD J. REED, University of Washington
GEORGE C. REID, National Oceanic and Atmospheric
Administration
JOSEPH L. REID, Scripps Institution of Oceanography
ELMAR R. REITER, Colorado State University
HERBERT RIEHL, Colorado State University
WALTER O. ROBERTS, University Corporation for
Atmospheric Research
GEORGE D. ROBINSON, The Center for the
Environment and Man, Inc.
EMANUEL D. RUDOLF, The Ohio State University
RICHARD J. RUSSELL, Louisiana State University
(Deceased)
JOHN R. RYTHER, Woods Hole Oceanographic
Institution
ELVIO H. SADUN, Walter Reed Army Medical Center
LYLE S. ST. AMANT, Louisiana Wild Life and
Fisheries Commission
FREDERICK SANDERS, Massachusetts Institute of
Technology
424
FREDERICK SARGENT II, University of Texas
at Houston
RICHARD A. 5CHLEUSENER, South Dakota School of
Mines and Technology
THEODORE W. SCHULTZ, The University of Chicago
J. ALLEN SCOTT, National Institutes of Health (Retired)
FRANCIS P. SHEPARD, Scripps Institution of
Oceanography (Retired)
JOANNE SIMPSON, National Oceanic and Atmospheric
Administration
ROBERT H. SIMPSON, National Oceanic and
Atmospheric Administration
JOSEPH SMAGORINSKY, National Oceanic and
Atmospheric Administration
TERAH L. SMILEY, The University of Arizona
RAY F. SMITH, University of California at Berkeley
STANFORD H. SMITH, National Oceanic and
Atmospheric Administration
FOREST W. STEARNS, The University of Wisconsin at
Milwaukee
ARTHUR C. STERN, The University of North Carolina
at Chapel Hill
HENRY M. STOMMEL, Massachusetts Institute of
Technology
EARL L. STONE, Cornell University
JOHN D. H. STRICKLAND, University of California at
San Diego (Deceased)
WILTON STURGES, III, University of Rhode Islan
JOHN C. F. TEDROW, Rutgers University
MARTIN A. UMAN, University of Florida at
Gainesville
GEORGE VAN DYNE, Colorado State University
JOHN VERHOOGEN, University of California at
Berkeley
BERNARD VONNEGUT, State University of
New York at Albany
FRANK H. WADSWORTH, Institute of Tropical
Forestry
PAUL E. WAGGONER, The Connecticut Agricultural
Experiment Station
JOHN M. WALLACE, University of Washington
HELMUT K. WEICKMANN, National Oceanic and
Atmospheric Administration
JOHN M. WEIR, The Rockefeller Foundation
KARL F. WENGER, Forest Service
FRANS E. WICKMAN, The Pennsylvania State
University
FORD WILKE, National Oceanic and
Atmospheric Administration (Retired)
HAROLD G. WILM, University of Vermont
HATTEN S. YODER, JR., Carnegie Institution of
Washington
PAUL C. YUEN, University of Hawaii
CONSULTANTS
LOUIS J. BATTAN, The University of Arizona
JOHN E. CANTLON, Michigan State University
WILBERT M. CHAPMAN, Ralston Purina Company
(Deceased)
JULIAN R. GOLDSMITH, The University of Chicago
ROGER REVELLE, Harvard University
GILBERT F. WHITE, University of Colorado
STAFF DIRECTORS
EUGENE W. BIERLY, National Science Foundation
LAWTON M. HARTMAN, National Science Foundation
425
NATIONAL SCIENCE BOARD
(AS OF MAY 1, 1972')
Chairman
DR. H. E. CARTER, Coordinator of
Interdisciplinary Programs, University of Arizona
Vice Chairman
DR. ROGER W. HEYNS, President,
American Council on Education, Washington, D. C.
DR. R. H. BING, Visiting Professor of Mathe-
matics, Department of Mathematics, Uni-
versity of Texas at Austin
DR. HARVEY BROOKS, Gordon McKay Pro-
fessor of Applied Physics and Dean of En-
gineering and Applied Physics, Harvard
University
DR. ROBERT A. CHARPIE, President, Cabot
Corporation, Boston, Massachusetts
DR. LLOYD M. COOKE, Director of Urban
Affairs, Union Carbide Corporation, New
York, New York
DR. ROBERT H. DICKE, Cyrus Fogg Brackett
Professor of Physics, Department of Phys-
ics, Princeton University
DR. WILLIAM A. FOWLER, Institute Profes-
sor of Physics, California Institute of Tech-
nology
DR. DAVID M. GATES, Professor of Botany
and Director, Biological Station, Depart-
ment of Botany, University of Michigan
DR. NORMAN HACKERMAN, President,
William Marsh Rice University
DR. PHILIP HANDLER, President, National
Academy of Sciences
DR. CHARLES F. JONES, Vice Chairman of
the Board, Humble Oil & Refining Com-
pany, Houston, Texas
DR. THOMAS F. JONES, JR., President, Uni-
versity of South Carolina
DR. JAMES G. MARCH, David Jacks Profes-
sor of Higher Education, Political Science,
and Sociology, School of Education, Stan-
ford University
DR. ROBERT S. MORISON, Professor of Sci-
ence and Society, Program on Science,
Technology, and Society, Cornell Uni-
versity
DR. GROVER E. MURRAY, President, Texas
Tech University
DR. E. R. PIORE, Member, Board of Directors,
International Business Machines Corpora-
tion, Armonk, New York
DR. FRANK PRESS, Chairman, Department of
Earth and Planetary Sciences, Massachu-
setts Institute of Technology
DR. JOSEPH M. REYNOLDS, Boyd Professor
of Physics and Vice President for Instruc-
tion and Research, Louisiana State Uni-
versity
DR. FREDERICK E. SMITH, Professor of Ad-
vanced Environmental Studies in Resources
and Ecology, Graduate School of Design.
Harvard University
DR. ATHELSTAN F. SPILHAUS, Fellow,
Woodrow Wilson International Center for
Scholars, Smithsonian Institution
DR. H. GUYFORD STEVER, Director, National
Science Foundation
MR. RICHARD H. SULLIVAN, Assistant to the
President, Carnegie Corporation of New
York, New York, New York
DR. F. P. THIEME, President, University of
Colorado
Executive Secretary
MISS VERNICE ANDERSON, National Science Foundation
' Includes one vacancy.
426
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