| Notes |
NSF 66-3
WEATHER
AN
CLIMATE MODIFICATION
Repori 01 ine
SPECIAL COMMISSION ON
WEATHER MOIJIFICATION
NATIONAL SCIENCE FOUNDATION
WEAMER
AND
CLIMATE MODIFICATION
Repori 01 me
SPECIAL COMMISSION ON
WEATHER MODIRCATION
NATIONAL SCIENCE FOUNDATION
LETTER OF
RANSMITTAL
The Honorable Leland J. Haworth
Director
National Science Foundation
Washington, D. C.
Dear Dr. Haworth:
It is an honor to transmit herewith
to the National Science Foundation
the report of the Special Commission
on Weather Modification, authorized
by the National Science Board at its
meeting on October 17-18, 1963, in
accordance with Sections 3(a)(7) and
9 of the National Science Foundation
Act of 1950, as amended, and
appointed by you on June 16, 1964.
The Commission was requested to
examine the physical, biological, legal,
social, and political aspects of the field
and make recommendations concerning future policies and programs.
The physical science aspects have
been studied primarily through
cooperative liaison with the National
Academy of Sciences' Panel on
Weather and Climate Modification.
Much of the background work for the
treatment of the other aspects of the
problem was carried out under
National Science Foundation grants or
contracts, reports of which research
and study are to be published as
stated in the Appendix.
The Commission held eleven
meetings supplemented by many days
of study, research, writing and
conferences. The Commission report
has been prepared by and its content
is concurred in by all the members
of the Commission.
The Commission was assisted
throughout its deliberations by an
Executive Secretary. Dr. Edward P.
Todd served in this capacity during
the early months. Mr. Jack C.
Oppenheimer succeeded Dr. Todd
and has done an outstanding job of
assisting the Commission.
Respectfully submitted,
A. R. Chamberlain, Chairman
Vice President
Colorado State University
December 20, 1965
I"
The Commission was established
pursuant to Section 3(a)(7) and 9 of
the National Science Foundation Act
of 1950, as amended.
The names and affiliations of the
Commission members are:
A. R. Chamberlain, Chairman
Vice President, Colorado State University
John Bardeen, Vice Chairman
Departments of Physics and Electrical
Engineering
University of Illinois
William C. Colman,
Executive Director
Advisory Commission on
Intergovernmental Relations
John C. Dreier
School of Advanced International Studies
The Johns Hopkins University
Leonid Hurwicz
Department of Economics
University of Minnesota
Thomas F. Malone,
Second Vice President
Research Department
Travelers Insurance Company
Arthur W. Murphy
Columbia University School of Law
Sumner T. Pike
Lubec, Maine
William S. von Arx
Massachusetts Institute of Technology
and Woods Hole Oceanographic
Institution
Gilbert F. White
Department of Geography
University of Chicago
Karl M. Wilbur
Department of Zoology
Duke University
SPECIAL
COMMISSION
ON
WEATHER
MODIFICATION
iv
ONTENT$
LETTER OF TRANSMITTAL .............................. iii
SPECIAL COMMISSION ON WEATHER MODIFICATION iv
HISTORICAL BACKGROUND ............................1
SUMMARY.............................................7
Introduction ........................................ 7
Scientific Possibilities ...............................11
Biological Implications ............................... 18
The Social Effects .....................................20
TheLaw ........................................... 23
Needs and Opportunities for International Cooperation ... 26
Fiscal and Organizational Considerations ...............29
PROGRESS AND PROSPECTS IN WEATHER AND CLiMATE
MODIFICATION ....................................34
Introduction .................................... 34
The Nature of the Scientific Problem ............... 34
Present Status of Weather Modification ............. 38
Accomplishments of the National Science Foundation
Program ................................... 43
Activities in Foreign Countries .................... 47
Perspectives for Research ........................ 50
Conclusions and Recommendations ................ 58
BIOLOGICAL ASPECTS OF WEATHER MODIFICATION ..... 60
Introduction .................................... 60
Means of Predicting Consequences of Weather Modifi-
cation ...................................60
Predicted Biological Responses of Weather Modifica-
tion.........................................65
Conclusions and Recommendations of The Ecological
Society Working Group .....................69
STATISTICAL ASPECTS OF WEATHER MODIFICATION .... 71
The Present Situation .........................71
The Conferences on Statistical Methodology ........71
Conference Findings ........................... 72
Conference Recommendations ................... 73
V
Precipitation-Oriented Experiments ............... 74
The Empirical Approach ......................... 75
Numerical Modeling and Simulation ............... 76
Commission Recommendations ................... 77
Footnote ...................................... 79
THE HUMAN EFFECTS OF WEATHER AND CLIMATE MODI-
FICATION ......................................... 80
WEATHER MODIFICATION AND INTERNATIONAL RELA-
International Programs Related to Weather Modifica-
Four Interlocking Systems ....................... 82
Uncertainty ................................. 84
Two Approaches to the Human Dimensions ........ 85
Broader Considerations ..................... 85
Evaluating Social Effects ...................... 86
Conflicts of Interest ............................. 90
Desirable Courses of Action ...................... 92
Recommendations .............................. 97
Footnotes...................................... 98
LEGAL AND LEGISLATIVE ASPECTS .....................100
TIONS............................................. 113
tion..................................... 115
International Requirements of Research ............ 117
Weather Modification and World Politics ..........118
Relation to U. S. Foreign Policy .................. 119
International Impact on U. S. Program ............. 120
Organization of Inter-Governmental Cooperation . . . . 121
Scientific and Technical Exchange ................ 122
International Legal Problems ..................... 122
Questions of International Organization ............ 123
Recommended Basic Policy Statement ............. 124
FUNDING AND ADMINISTRATION REQUIREMENTS ....... 126
Federal Financial Support of Weather and Climate Mod-
ification .................................... 126
Administration .................................. 130
APPENDIX............................................. 149
vi
HISTORICAL
BACKOHOUND
Twenty years ago General Electric
Company scientists Irving Langmuir
and Vincent Schaefer modified clouds
by "seeding" them with dry ice pellets. Not long afterward Bernard Vonnegut, a co-worker, demonstrated that
a smoke of silver iodide crystals
would accomplish the same result.
This was the beginning of the modern
American history of weather and climate modification through cloud
seeding.
These American scientists on November 13, 1946, had verified experimentally the theory advanced in 1933
by the Swedish meteorologist, Tor
Bergeron, and the German physicist,
Walter Findeisen, that clouds would
precipitate if they contained the right
mixture of ice crystals and supercooled water drops. The BergeronFindeisen theory was antedated by
the work of the Dutch scientist, August Veraart. The enthusiastic reports
by Veraart of his 1930 experiments
with dry ice and supercooled water-ice
in Holland were not well received by
the Dutch scientific community, and
thus were given no serious consideration elsewhere.
Weather and climate modification,
or "rainmaking" (the more popular
and also more restricted concept), is
not new to our era or to our country.
Many traditional societies, including
the American Indians, have practiced
some type of religious or ritualistic
rainmaking. The ceremonials and rituals have varied from dousing holy
men with water to burying children
up to their necks in the ground in the
hope that the gods would be sympathetic and drop tears from the heav
ens. These ceremonies are not only to
induce some form of desirable weather
but also to reinforce the tribal religious beliefs and opinions which
maintain social unity.
Through ancient and modern times
many methods have been proposed
and attempted to induce or to aid
rainfall. Two U. S. Government patents on methods of rainmaking were
issued before the turn of the 20th
century based, respectively, upon the
production of carbon dioxide by expending "liquified carbonic acid gas"
and upon concussion by the detonation of explosives. Interestingly
enough the long since expired patent,
based on the production of carbon
dioxide in the form of dry ice, anticipated the cloud seeders of today. The
pioneering field and laboratory work
of meteorologists in the War and Navy
Departments on the popular notion
1
that rainfall could be caused by the
detonation of explosives was supported by Federal Government funds.
Even social, political and legal conflicts over weather and climate modification are not new. In 1916 San
Diego's employment of a rainmaker,
resulting in claims of loss of life and
property damage of a million dollars,
anticipated by half a century the litigation and State and local legislative
action of today.
The 1946 demonstration that clouds
might be modified and rain produced
by scientific methods arose out of the
World War II investigations of fog
particles by Langmuir and Schaefer.
The military possibilities of this discovery led the armed services to support a broad theoretical, laboratory
and field program in cloud modification from 1947 to 1952, known as
Project Cirrus. Civilian and military
implications were investigated by the
Cloud Physics Project of the U. S.
Weather Bureau, Air Force and National Advisory Committee for Aeronautics from 1948 to 1951. The military services followed the termination
of Project Cirrus in 1952 with a Department of Defense 5 year Artificial
Cloud Nucleation Project.
Whether or not the multi-million
dollar commercial rainmaking activities of the late 1940's and early 1950's
grew out of the obvious interest of the
Federal Government in weather and
climate modification research or the
coincidental severe drought conditions
in some parts of the nation, relatively
vast operations became a fact of life.
It was disclosed between 1951 and
1953 in the Congressional Hearings
leading up to the establishment of the
Advisory Committee on Weather Control that during the height of cloud
seeding activities $3 to $5 million a
year was being spent by water users,
particularly in the West, for commercial cloud seeding, and that about
10% of the land area of the United
States had become the target of cloud
seeding attempts.
The weather modification events of
the late 40's and early 50's in the
United States encouraged cloud seeding programs in Australia, France and
South Africa to increase precipitation
and renewed the scientific interest in
hail suppression that had been practiced in Alpine Europe since the mid
30's. The dozen nations experimenting
with cloud seeding during the late
1940's more than doubled by 1951 to
2
about 30 countries representing every
continent.
Meanwhile, the drought that held
sway in many parts of the country,
the claims of some of the rainmakers
and the criticism from portions of the
scientific community led the Congress
to create an Advisory Committee on
Weather Control to study and evaluate public and private experiments in
weather modification. In its final report in 1957 the Advisory Committee
on Weather Control found, among
other things, on the basis of statistical
evaluations, that cloud seeding in the
mountainous areas of western United
States of storms occurring during the
cooler and moist winter and spring
months produced an average increase
in precipitation of 10 to 15 percent
from seeded storms with a satisfactory degree of probability that the increase was not the result of natural
variations in the amount of precipitation. On the basis of its physical evaluations, the Committee found, among
other things, that seeding from the
ground with silver iodide generators
is a valid technique for seeding clouds.
As a consequence of these findings
and their related scientific and technical studies the Advisory Committee
on Weather Control recommended:
The development of weather
modification must rest on a foundation of fundamental knowledge
that can be obtained only through
scientific research into all the physical and chemical processes in the
atmosphere. The Committee recommends the following:
That encouragement be
given for the widest possible
competent research in meteorology and related fields. Such research should be undertaken by
Government agencies, universities, industries, and other organizations.
That the Government sponsor meteorological research more
vigorously than at present. Adequate support is particularly
needed to maintain continuity
and reasonable stability for longterm projects.
That the administration of
Government-sponsored research
provide freedom and latitude for
choosing methods and goals. Emphasis should be put on sponsoring talented men as well as their
specific projects.
That an agency be designated to promote and support re3
search in the needed fields, and
to coordinate research projects.
It should also constitute a central point for the assembly, evaluation, and dissemination of information. This agency should be
the National Science Foundation.
(5) That whenever a research
project has the endorsement of
the National Science Foundation
and requires facilities to achieve
its purpose, the agency having
jurisdiction over such facilities
should provide them.
The above recommendations of the
Advisory Committee on Weather Control together with the 1957 report of
the American Meteorological Society
and the 1958 third report of the Committee on Meteorology of the National
Academy of Sciences emphasized the
need for: fundamental knowledge;
research; experimentation; education
and training in meteorology and related fields; promotion, support, coordination, evaluation and information assembly and dissemination by
the National Science Foundation; and
increased Federal support to universities for basic research in the atmospheric sciences.
On July 11, 1958, the President approved PL 85-510 which, in pertinent
part, authorized and directed the National Science Foundation to:
• . . initiate and support a pro
gram of study, research, and evaluation in the field of weather modification, giving particular attention
to areas that have experienced
floods, drought, hail, lightning, fog,
tornadoes, hurricanes, or other
weather phenomena, and to report
annually to the President and the
Congress thereon.
consult with meteorologists
and scientists in private life and with
agencies of Government interested
in, or affected by experimental research in the field of weather control.
• . . carry out the purposes .
whether conducted by the Foundation or by other Government agencies or departments, . . . through
contracts with, or grants to, private
or public institutions or agencies,
including but not limited to cooperative programs with any State
through such instrumentalities as
may be designated by the governor
of such State.
4
Thus, for the last 7'/2 years the
Foundation has been providing major
support for the Federal Government's
weather modification program and
also has been a focus for Government-wide program planning and
coordination through various mechanisms, including its annual Interagency
Conference on Weather Modification.
During this same period, the Departments of Agriculture, Commerce,
Defense, and Interior have either initiated or continued mission-oriented
programs of research and development in weather and climate modification. These programs have been devoted to such matters as research on
the suppression of lightning-induced
forest fires by the U. S. Forest service;
observation, analysis and experimental seeding of severe storms and hurricanes by the U. S. Weather Bureau;
cloud physics research, experimental
seeding of clouds and dispersal of
clouds and fog by the military departments; and research on reduction of
water evaporation through use of
chemical films and increase of water
supplies through research and experimental seeding by the U. S. Department of the Interior.
The FY 1966 total annual spending
for all the various Federal agency
programs of weather modification research and development is about 7.2
million dollars. During the year ending June 30, 1965, there were 59 cloud
seeding projects by 15 commercial
operators concerning operations in 26
different states. At present there are
research activities reported from 15
foreign nations.
In November 1963, in response to
increased concern over the potentialities for man-made changes of weather
and climate and the interest in undertaking large scale weather modification activities, the Committee on Atmospheric Sciences of the National
Academy of Sciences (NAS) appointed
a Panel on Weather and Climate Modification "to undertake a deliberate
and thoughtful review of the present
status and activities in this field, and
of its potential and limitations for the
future." On June 16, 1964, the Director of the National Science Foundation announced the appointment of
the Special Commission on Weather
Modification, as previously authorized
by the National Science Board at its
89th Meeting on October 17-18, 1963.
The Commission was assigned to: (1)
fulfill the need of the National Science
Foundation for a review of the state
of knowledge on weather and climate
5
modification, make recommendations
concerning future policies and programs and examine the adequacy of
the Foundation's program; and (2)
respond to the request of the Interdepartmental Committee for Atmospheric Sciences of the Federal Council for Science and Technology of
August 19, 1963 to prepare an analysis of the modification and control of
the weather for useful purposes other
than military. The Commission's assignment included consideration of
not only the scientific aspects but also
the legal, social and political problems in the field.
In view of the broad categories of
questions directed to the Commission
by the National Science Foundation,
the Commission activated seven subgroups, each of which was headed by
one or more members of the Commission. The physical, biological, statistical, social, international, legal and
legislative, and administration and
funding aspects have been studied by
these sub-groups. The physical science aspects have been studied primarily through cooperative and continuing consultation and liaison with
the National Academy of Sciences'
Panel on Weather and Climate Modification. Much of the background
work for the treatment of the various
aspects of the problem was carried
out under National Science Foundation grants or contracts. Reports of
these research and study activities
are to be published as stated in the
Appendix. The National Academy of
Sciences has just completed its final
report, entitled Weather and Climate
Modification—Problems and Prospects, Vols. I and II.
6
SUMMARY
INTRODUCTION
Man is becoming so numerous and
his influences on his environment so
profound that he cannot consider himself free to heedlessly or improvidently exploit the air, water, land, and
growing things of this earth. He no
longer lives under the constant threat
of a wilderness but, instead, is changing his environment and, therefore,
must plan for its conservation and
development.
With advances in his civilization
man has learned how to increase the
fruit of the natural environment to insure a livelihood. The main problems
which now threaten his future are:
large-scale, catastrophic warfare;
providing sustenance for a rapidly increasing population;
waste disposal and environmental change accompanying
the discharge of matter into the
atmosphere, open waters, and
subterranean spaces.
Recognizing these circumstances of
human activity, it is fortunate that
growing knowledge of the natural
world has given him an increasing
awareness of the changes that are
occurring in his environment and also
hopefully some means for deliberate
modification of these trends. An appraisal of the prospects for deliberate
weather and climate modification' can
be directed toward the ultimate goal
of bringing use of the environment
into closer harmony with its capacities and with the purposes of manwhether this be for food production,
relief from floods, assuring the continuance of biologic species, stopping
pollution, or for purely aesthetic reasons.
The National Science Foundation
Special Commission on Weather Modification was asked to consider one
aspect of the problem of environmental conservation and utilization.
With the physical possibility of modifying the weather and climate already
partly demonstrated, it is important to
inquire: How by artificially inducing
deliberate changes in the environment
may man act to control or develop
'Throughout this report the term "weather
and climate modification" is taken to mean
artificially produced changes in the composition, motion, or dynamics of the atmosphere, whether or not such changes may be
predictable, their production deliberate or
in advertent, or their duration transient or
permanent.
7
changes in the atmosphere considered
to be desirable by society? With this
question in mind, the Commission has
concerned itself with the physical, biological, social, engineering and legal
aspects of weather and climate modification.
Weather and climate modification
is becoming a reality. The daily activities of man influence the atmosphere
in a number of ways and his ability
to induce deliberate changes in measurable magnitude by artificial means
is progressing. The scale of known
operational ability for deliberate routine weather modification is presently
the dissipation of supercooled fog and
stratus over an area approximately the
size of an airport, for a short period
of time. On a larger scale, the inadvertent modification of the weather
and climate by such influences as the
products of urban development, surface modification for agriculture and
silviculture, compositional changes
through the combustion of fossil fuels
and other exhausts are becoming of
sufficient consequence to affect the
weather and climates of large areas
and ultimately the entire planet.
Deliberate modification of weather
and climate may be accomplished by
not only artificially influencing the
atmosphere but by controlling inadvertent changes. For example, smog
is the result of deliberate pollution
which causes inadvertent modification
of urban weather and climate. A number of questions are involved:
If deliberate modification of the
atmospheric environment is already
a growing physical possibility, what
are the scientific prospects for the
future?
What may be the biological consequences of weather and climate
modification activities?
What might be the social, human
and economic benefits to man?
Are there legal, political and
legislative issues to be resolved?
How should the plans of the
United States in weather and climate
modification be communicated to and
coordinated with other nations?
What are the organizational and
funding needs for a national program
in weather and climate modification?
These questions are explored in
some detail in the body of the report.
Summarized here are some of the Commission's findings and conclusions
relevant to these questions.
8
Scieniffic Prospects
Several cubic miles of supercooled cloud droplets can be transformed into ice crystals by seeding
with dry ice or silver iodide. Supercooled fog on the ground can be dissipated. No practical approach to the
dissipation of warm fog is at hand.
While the evidence is still somewhat ambiguous, there is support for
the view that precipitation from some
types of clouds can be increased by
the order of ten percent by seeding.
If the results are confirmed by further
studies they would have great significance. The question of corresponding
decreases of precipitation outside the
target area is unresolved.
Results from attempts to suppress hail in the United States are as
yet inconclusive but more promising
results in other countries are leading
to the establishment in this country
of a program that should provide a
more definitive answer.
Experiments in lightning suppression are beginning to show some
promise.
Modification of hurricanes has
reached the stage of preliminary field
experimentation but the results, so far,
are inconclusive.
Changing the course or intensity
of extratropical cyclones and altering
climate over large areas remain as
problems for the future. No serious
attempt has yet been made to control
tornadoes.
Inadvertent changes in climate as
a consequence of human activity (e.g.,
urbanization, air pollution, increase of
atmospheric carbon dioxide by burning fossil fuels) are amenable to analysis and deserve early attention.
With respect to the scientific prospects for the future, the Commission
finds that attractive opportunities exist.
Advanced experimental techniques
and application of sophisticated concepts in statistical design promise to
reduce the present uncertainty in the
interpretation of field experiments.
The scientific exploration of weather
and climate modification is passing
from the speculative phase to the
rational phase. Within reach are
mathematical and laboratory modeling
techniques that permit the simulation
of atmospheric processes. By these
means it should become possible to
assess in advance the probable consequences of deliberate intervention.
9
An expanded program of basic and
applied research is needed to take
advantage of these scientific opportunities.
Biological Consequences
Great uncertainty has been encountered regarding the biological consequences of weather and climate modification. Augmentation of rainfall over
cultivated areas could partially alleviate the increasing problem of food
production. However, there is an accompanying possibility that instabilities might result in the balances of
biological communities. Such imbalances can be expected in the diseases
and pests of man's domesticated plants
and animals. In small areas of natural
communities it is possible that some
wild species may be severely stressed.
The timing of the atmospheric intervention relative to the reproductive
cycle of the various species in the
community may be of more importance than the magnitude of the intervention. Both field and simulation
studies of these biological relationships are needed before, during and
after sustained operational programs.
These studies should help avoid undesirable, unanticipated and irreversible ecological changes.
special impucanons
Weather and climate are among the
major determinants of economic and
social activity. Any change in precipitation, temperature, and windwhether deliberate or inadvertent—is
likely to have a significant effect upon
society. Although a number of techniques are available for the study of
the economic and social impact of
weather modification, relatively little
has been done. Much remains to be
learned of the manner in which man
responds to the normal variability in
weather conditions. Relatively little is
known of the processes of decisionmaking in human activities in relation
to present day weather prediction.
Economic and social analysis of these
relationships is urgently required as
an aid in developing and applying
techniques of weather and climate
modificiation. If the developing techniques of weather and climate modification are to be used intelligently,
the human consequences of deliberate
or inadvertent intervention need to be
anticipated before they are upon us.
10
Mal ASPeCtS
Weather and climate modification
poses legal questions as to the existence of "property" interests in weather
and the responsibilities of weather
modifiers for damage to others, as well
as problems of regulation. It is too
early to make specific suggestions as
to the law which should govern "property" in weather, or the liabilities of
weather modifiers. However, recommendations are made as to needed
regulation and indemnification of those
working on government supported
programs.
InIernallonal Reiallons
The Commission finds far-ranging
international implications in weather
and climate modification. By its very
nature weather transcends national
boundaries. An attractive opportunity
exists to anticipate the effect of technological development in weather and
climate modification upon international relations. Specific steps are
recommended to foster international
cooperation in research and in the
peaceful use of any physical capability
that may evolve.
Oruaouzation aM filMs
The national program should involve
basic research, technology, operations
and regulation. There needs to be
assigned to a single existing government agency, or to a completely new
agency, the responsibility for developing the technology of weather and
climate modification. The National
Science Foundation should continue
and expand its support of research
in the atmospheric sciences, including
its program directed at providing a
satisfactory scientific basis for weather
and climate modification. Other governmental agencies should undertake
such research and operational activities in weather and climate modification as their missions may require.
Federal financial support for research and development activity in
weather and climate modification
should be increased several fold over
present levels.
SCIENTIRC POSSIBILITIES
In pursuing means to modify weather
and climate man assumes the character of a force of nature. That state is
not at all novel in that man by mad11
vertent acts has already modified some
aspects of weather and climate through
urban development, surface changes
for agriculture, forest culture and
flood control, and altered the composition and thus the radiation balance
of the atmosphere through the combustion of fossil fuels. Deliberate
alteration of the atmospheric regimen
is, however, a new concept. Thus far
the brightest hope for deliberate intervention lies in the possibility of altering precipitation rates and dissipating
supercooled fog by silver iodide or dry
ice seeding. This has caused the prospect of weather and climate modification to be viewed mainly in the light
of these techniques and their attendant geographic scales.
If it is granted that the possibility
of successful use of seeding procedures
is a real one, it must also be recognized that it is in the character of
modern man that he will press on to
develop larger scale measures; some
of which are already in the conceptual
stages of evolution. For this reason,
planning for research in weather and
climate modification must be broad
enough at its very outset to accommodate future progress toward large scale
or manifold activities. Moreover, judgment of sound action must be based
on a suitably broad foundation of informed scientific, economic, legal and
other opinion, with a clear appraisal
especially of the biological and ecological risks involved.
There are four needs to be met in
weather and climate modification:
To assess and understand natural
climatic change.
To assess and understand the
inadvertent changes in weather and
climate that the technological evolution of man has produced;
To improve man's ability to predict the behavior of the atmosphere
so that he may arrange his affairs with
a minimum of danger or surprise; and
To devise a variety of techniques
for deliberate intervention in the
course of atmospheric (or other) processes which will alter weather and
climate in the interest of mankind.
Why attention to the field is timely
is well explained in the Introduction
to Vol. I of the Report of the Panel on
Weather and Climate Modification of
the National Academy of Sciences.'
1 Weather and Climate ModificationProblems and Prospects, Vols. I and II, National Academy of Sciences-National Research Council, 1966 (NAS-NRC 1350). Volume II contains an extensive bibliography.
12
One might ask why so detailed a
survey of the status and outlook of
atmospheric modification as we have
made should be undertaken at this
time. During approximately the past
decade, subtle but significant shifts
have occurred in long-term prospects
for weather and climate modification;
in many fundamental respects, an
earlier era of speculation had gradually been superseded by the present
period in which rational and systematic exploration of modification potentialities has become possible. Several changes stand out as factors
causing this shift:
Formulation of increasingly complete and elaborate theories of atmospheric processes has advanced to a
state in which moderately realistic
mathematical models can be constructed for a variety of atmospheric
systems ranging in scale from micrometeorological to global. Admittedly
crude and rudimentary in many instances, such models constitute a
necessary first step in reducing the
degree of empiricism that has characterized most past speculations concerning atmospheric modification.
Prior to about 1950, such mathematical models were for the most part
unproductive because of the sheer
mathematical complexity of the systems of equations constituting the
models. The advent of high-speed
automatic computers has, within the
past decade or so, radically altered
this picture. Computing speeds and
storage capacity have risen by many
orders of magnitude, and a growing
body of investigators in the atmospheric sciences has seized this powerful new tool to use it in analyzing
critical aspects of the physics of our
atmosphere. The important practical
goal of improved numerical weather
prediction became a stimulus that has
recently led many workers to conduct increasingly elaborate computer
studies in the broad area of numerical
experimentation. Today, numerical
simulation, albeit impressively complex and varied in scope, is almost
certainly only a primitive first step
toward future levels of understanding
of the subtle and highly interdependent workings of our atmosphere; but
it is a beginning with foreseeably profound implications for weather modification. This development alone is
significant enough to justify a new and
deeper examination of modification
prospects.
13
(3) Man's ability to measure and to
observe the atmosphere with its myriad
parameters has been growing steadily.
Two decades of improvement in use
of aircraft as measurement platforms,
two decades of elaboration of radarmeteorological techniques, and soon
a full decade of experience with the
incomparable synoptic observing capabilities of the meteorological satellite,
combine with many other advances
in instrumentation and observation
systems to permit almost entirely new
dimensions in man's ability to keep
track of the rapid changes that are so
characteristic of weather. Clearly, still
further improvements may be expected
in the future, but one senses that
already we have available the measurement skills requisite to monitoring
adequately many of these atmospheric
systems we seek to modify.
The three considerations discussed
above are of sufficient basic importance to prospects for present and
future weather modification that, even
without the particular stimulus of current advances in cloud modification
per Se, it would be most timely to
undertake a survey of the field of
atmospheric modification.
Much of the present effort in weather
modification stems from the suggestion in 1946 of Langmuir and Schaefer
that precipitation could be enhanced
by introduction of ice, or ice-like
nuclei, into clouds. The basis for the
suggestion is that condensation of
water droplets into particles large
enough to fall may occur by growth
of ice crystals in supercooled parts of
the cloud. Water droplets may be
supercooled well below the freezing
point unless freezing nuclei are present. If clouds lack a sufficient number
of natural nuclei, precipitation could,
according to the theory, be enhanced
by introduction of artificial nuclei into
the appropriate parts of the cloud. In
subsequent years the many experiments done in this country and abroad
to test the theory have led to inclusive
and controversial results. It has only
been during the past year, largely as
a result of a thorough analysis of
available data by the NAS Panel on
Weather and Climate Modification,
that statistical evidence, although still
somewhat ambiguous, appears to show
that precipitation can be modestly
enhanced locally by seeding.
Most of the experiments on which
this conclusion is based are of an
empirical nature. Typically nuclei are
14
introduced by ground-based silver
iodide generators. Rainfall is measured in a target area extending perhaps 30 to 50 miles downwind and
also in a control area upwind from
the generators. By comparing the observed rainfall during the seeding
operations in the two areas with averages over past years, one can estimate
the increase, if any, caused by seeding.
In some cases the seeding is done on
a randomized basis and a comparison
is made between seeded and unseeded
days and areas. Because of the wide
variability of cloud systems, a great
deal of data is required to obtain statistically significant results and also to
ascertain under what conditions and
what geographical locations seeding
may be effective. The possibility of
some sort of systematic error or bias
must be eliminated by statistical
design.
There is need for more empirical
studies carefully designed to determine how effective seeding is in increasing rainfall or in suppressing hail
and lightning in various situations.
These experiments should be designed
to give reliable and statistically significant data.
Toward this end a program of
planned field experiments should be
undertaken which provide continuity
over a period of 5 to 10 years on a
sufficient scale to permit geographic
comparisons and differentiation, as
well as stratification according to the
type of seeding agent, mode of injection, cloud type, etc. Provision should
be made for the inclusion of relevant
precipitation data in addition to other
relevant physical variables. This program should be designed and evaluated in close association with statisticians with extensive experience in
experimental design.
Another approach is through basic
research on cloud physics. These
studies have shown that cloud systems are extremely complex and that
precipitation can probably occur in a
number of ways. There is only a rudimentary knowledge of how the artificially induced nuclei enter the clouds
and how precipitation is actually
affected. Thus, there is a wide gap
between the basic research studies
and cloud physics and an understanding of the empirical results of seeding.
In order to optimize seeding procedures and to better assess their inherent limitations, much more must be
learned about the actual physical
mechanisms involved. This requires
more elaborate and expensive field
15
experiments in which a number of
variables are measured in addition to
over-all precipitation, or, in the case
of hail studies, the amount and nature
of the hail.
A number of suggestions have been
made of possible methods to produce
changes in the climate extending over
large areas. It is known that rather
abrupt changes in climate have occurred in the historical past, but there
is as yet little understanding of the
factors which brought them about. It
is possible that changes in climate
may also be produced inadvertently
by activities of man. To assess the
probable consequences of both deliberate and inadvertent changes requires
much better knowledge than is now
available of the general circulation of
the atmosphere and oceans, sources
and sinks of heat, and energy interchanges at the surface of the earth.
To acquire such knowledge will require many years of basic research.
Man is now learning how to simulate
the atmosphere numerically with use
of large digital computers and by use
of laboratory models. It has been estimated that computers two orders of
magnitude faster than those now in
use will be required for adequate
simulation of the atmosphere on a
global scale for general circulation and
on a limited scale for local storms.
A broad research program of this sort
is required and can be justified for aid
in long-range forecasting. Its importance for making possible predictions
of consequences of deliberate and
inadvertent modifications of climate
gives it added justification.
Computer simulation and other
studies should include a search for
triggering mechanisms and means for
suppressing violent but marginally sustained extremes in weather. Further
development of laboratory and computer simulation should also yield
insights crucial to the design of field
experiments, to systematic efforts to
modify weather and to long-range
international planning of non-atmospheric methods of weather and climate modification.
It is assumed that the mission-oriented programs already underway,
such as that of the Department of
Interior to attempt to increase precipitation over its Reclamation project
watershed areas and those of the Departments of Agriculture, Commerce
and Defense will be continued in both
their scientific engineering and operational phases. These present experiments should be continued. But, it is
16
essential that there be an increase of
effort, either by agencies of government or by academic and other groups
to insure that the biological, legal,
social and statistical aspects of the
experiments are given sufficient attenti on. Present mission-oriented field
experiments are examples of work
undertaken despite the fact that there
has been insufficient fundamental research. If large-scale field seeding
activities are properly designed and
controlled and can be supported by
adequate ecological investigations,
with monitoring and associated fundamental research, there is no question
that such experiments will yield knowledge benefiting weather modification
research while the public policy objective of attempting to increase precipitation over the watersheds is being
pursued.
One can conceive of non-atmospheric possibilities for deliberate
weather and climate modification
which could lead to major changes in
climate. An example is possible alteration of the oceanic heat balance by
lifting cold water to the surface in
major currents such as the Gulf Stream
or Kuroshio (Japan) Current. Such experiments should obviously not be
undertaken without many years of international study of all consequences.
But, the increasing levels of energy
available to man are even now so
great that such proposals may be
entertained.
To carry out the necessary laboratory, field and theoretical research for
a full understanding of atmospheric
and non-atmospheric weather and climate modification and inadvertent
changes in weather, will require the
efforts of people well qualified in disciplines such as applied physics, engineering, chemistry, statistics and meteorology, as well as biology, geology,
oceanography, mathematics and hydrology.
In the view of the Commission,
some of the greatest future needs of
the physical sciences and engineering
in weather and climate modification
research and development are: enhancement of the support of fundamental research looking to creative
ideas; much greater logistics capability
for supporting large-scale experiments
whether over sea or land; careful attention to the statistical design of experiments; a larger program in computer
simulation and laboratory geophysical
modeling; and consideration of synchronous satellites for observing the
life history of storms such as hurricanes.
17
RIOLOOIUL IMPLICHIONS
Man is an organism directly dependent on other organisms for many
of his materials. He also struggles
with other organisms, most of them
quite small, that prey upon him, eat
his food, or otherwise challenge his
existence. Anything that has a general
and significant effect upon plants and
animals, making some more abundant,
others less so, is of primary concern
to mankind, for it strikes at the very
basis of human existence. Changes in
weather and climate may be expected
to have such effects. It follows that
any program of weather and climate
modification must give serious attention to adverse as well as beneficial
biological aspects.
It must be recognized that the present state of knowledge places uncomfortable demands on the prediction of
the biological consequences of modifying the weather. Prediction of the
impact of weather modification on the
biological components in man's artificial ecological systems such as his
cities and his farms will probably be
easier to attain than such prediction
for the more nearly wild areas. This
is so, because economic objectives
have insured more adequate biological
information concerning artificial systems, and because these systems are
not so complex biologically. It is essential that this present primitiveness
in our biological forecasting capability
not be used as an argument for omitting it from weather modification programs.
Prediction of the types and degrees
of change in crop and livestock yield
and quality to be expected from specific changes in weather sequences
can be markedly improved with methods and analyses already at hand.
Prediction of the direct effects of
weather changes on the domesticated
organism can be attained more
quickly than prediction of the indirect
effects resulting from weather-induced changes to the domesticants'
parasites, diseases, pests and symbiants. The published literature contains
many references to studies implicating unusual weather sequences for
disease and insect and weed outbreaks. Vector-born diseases of plants
and animals, humidity-responsive bacterial and fungal diseases of crops and
many insect outbreaks can be cited as
examples. A fuller knowledge of these
inter-relations coupled with a capability of highly accurate control over the
18
weather could have favorable economic results. Ignorance concerning
the biological consequences to be expected from significant changes in the
weather could be locally detrimental.
In wild lands the complex natural
arrays of organisms are in delicate
adjustment not only with the normal
climate but also with the pattern of
fluctuations. On the basis of the few
published long-term studies in which
biological composition has been followed during major weather fluctuations, it seems a reasonable prediction
that alterations in weather patterns
are likely to constitute at least a temporary unstabilizing influence in most
natural biological communities. It is
important to note that weather and
climate fluctuations have been a molding influence on natural populations
and most species have adaptations relating to it. Thus, weather and climate
modifications need not constitute
changes exceeding the recorded extremes in order to cause significant
biological consequences. Some of the
successional species that tend to increase during instability may be economically important species such as
the succession of many forest species.
Since many pests are also favored
during instability, the net economic
effect is difficult to predict.
In vast reaches where the biological
communities extend beyond the areas
of weather modification it can be expected that natural migrations of
species from areas adjacent to the
changed condition will tend ultimately to restore stability. However,
in the small islands of natural biological communities such as parks and
preserves the effects will be less apt
to set themselves right. The wide
stretches of man's artificial biological
make-up and disturbance between
such islands provides an effective barrier to migrations. Extinction, at least
locally, could result for some species.
Thus, from the present crude state
of the field, one can roughly predict
that the biological outcomes of
weather modification are apt to be a
mixed bag of economically good and
bad effects in man's artificial ecosystems. It is difficult to visualize any
desirable effect on the small preserves
of natural communities. In order to
improve biological forecasting several
avenues are open:
1. Growth chamber simulation of
such changes on as large a fragment
of the biological type as possible.
19
Examination of areas biologically
and climatically analogous to the
changed and unchanged situations.
Study of the fine structure in the
fossil record of the recent past.
Computer simulation of changes
using the best available data.
Monitoring of sample areas
within and outside of regions subjected to weather modification. The
monitoring should begin before
weather modification activities and
extend beyond their cessation.
It is the position of the Commission
that there should be a strong effort
to bring the field of biological forecasting up to a higher level of usefulness. This is mandatory in planning
weather and climate modification over
areas involving more than a few hundred square miles.
A by-product of such expanded research and development will have
wide utility in agriculture, forestry
and park and general resource management and other fields. Beyond this,
as an area of fundamental science,
forecasting of the behavior of ecological systems needs to be augmented
since man knows so very little about
how such systems operate, either the
man-made ones that sustain him or
the natural ones from which he derives an essential part of his inspiration and contentment.
All five of the above approaches
need to be brought to bear on the
problem. Any group involved with
large-scale experimentation with
weather modification should be expected to provide for adequate biological monitoring. The team effort
that would result from this kind of
interaction of meteorologists, hydrologists, engineers, ecologists, agronomists, foresters, entomologists, etc. is
long overdue.
THE SOCIAL EFFECTS
Weather and climate conditions are
among the major determinants of economic activities and social structure.
No other aspect of the environment
has as many pervasive relations to
the pattern of human activity on the
globe. Any substantial change in precipitation, temperature, or wind,
whether deliberate or inadvertent, is
likely to have a significant effect upon
society, as the public and private expenditures for hurricane, drought, and
flood disasters dramatically illustrate.
The immense varieties of housing and
20
of farm cropping practices illustrate
less obvious but fundamental adjustments to weather and climate. In some
cases the influence of weather and
climate modification on human activities may result in shifts of the social
institutions that are too subtle to be
recognized by many of those involved.
If scientific research in changing
weather and climate is regarded as
an investment decision, society should
seek answers to several questions as
it decides how much to spend for
what kinds of research. Who benefits
from the investment if made? If both
benefits and losses occur, how are
they distributed? Will the normal
market forces provide enough incentive to achieve the socially optimum
results to mankind?
It does not seem plausible that private enterprise will finance research
at a level adequate to achieve the
optimum social objective. Further,
because the benefits or losses do not
necessarily accrue to people in the
same geographic area or in the same
businesses, weather and climate modification research needs to be supported primarily from federal sources
for the foreseeable future. This position is to be expected when the estimate of the long-range social effects
and the apparent immediate value of
the products for the market are so
divergent.
A number of techniques are available for study of the economic and
social impacts of weather modification. These include benefit-cost analysis, activity analysis, input-output
analysis, and analysis of decision
making, as well as numerical simulation studies. Despite differences of
opinion as to research strategy, the
various techniques tend to be complementary. Much has been learned about
methods from the social appraisal of
engineering projects to modify the
water cycle in river channels.
One general approach is to define
an actual or assumed modification of
the weather and then attempt to analyze the full consequences of this to
society. It is practical, for example, to
estimate an increase in precipitation
over a drainage area serving a hydroelectric plant and then follow the possible impacts through the operation of
the plant, the operation of downstream
water projects, the production of
other plants connected in the same
system, and the productivity of the
entire network. Along with the cost
of cloud seeding, an attempt can be
made to measure the full social bene21
fits and costs from the increased rainfall, but these are hard to identify.
Another approach is to analyze a
sector of society so as to determine
the particular points in the life of
man where he is sensitive to changes
in weather, and the degree to which
a modification might lead to readjustment in amount or location of his
activity. For example, it is obvious
that the whole pattern of recreation
in an area can shift very quickly
because it happens to rain or snow at
a given time and place, and that if
the probability of precipitation were
to be changed, the character of the
regional recreation industry would
alter.
A basic difficulty in social research
associated with weather modification
is the difficulty of assessing the way
in which man responds to a known
weather circumstance. Just because
there is a drought it does not automatically follow that a farmer in that
area will move to another locality or
adopt a different cropping schedule,
even though analysis indicates it
would be most profitable to do so. He
may decide to stay, or to hold to his
old farming methods. Understanding
how people manage natural resources
is essential to sound prediction of
how they will react if the atmosphere
is modified.
Any adequate evaluation of social
effects examines and compares the
whole range of alternatives to weather
and climate modification. An accurate
weather forecast, for example, may
be more valuable than an increase in
rainfall, in some situations. If longrange forecasts were made reliable a
farmer could change his cropping pattern for that year rather than support
weather modification. As a further illustration, unless practical triggering
mechanisms can be found, increasing
the ability to forecast tornadoes and
hurricanes is more rewarding than attempting to modify them. Adequate
warning in many cases can allow man
to adapt his activities at lower cost.
There are other alternatives in addition to forecasting: agronomic and
genetic research can render farming
less susceptible to the vagaries of
weather. Engineering can protect
transport from weather interruptions.
A change in farm or industrial organization can reduce its vulnerability to
weather extremes.
The need is great to assess more
fully the social implications of weather
and climate modification resulting
from man's discharging material into
22
the atmosphere. As more is known
about the weather man could decide
to build cities on spoil areas rather
than on good farm land and in topographic areas which help avoid pollution of the environment. One alternative here, of course, is to modify the
weather over urban areas deliberately
to offset the results of man's inadvertent weather changes.
To the uncertainty as to what
weather and climate modification man
can accomplish must be added his
lack of knowledge of the full consequences. New research programs
should be based on the recognition
that expanding the scientific knowledge of these consequences would be
important to man even if no further
gains were to be made in the technology of weather modification. The same
understanding which would permit assessing the effects of weather and
climate alteration would assist in
working out other kinds of adjustments to weather phenomena.
As indicated by the lack of social
research about weather modification
since the 1957 report of the Advisory
Committee on Weather Control, when
uncertainty concerning the feasibility
of extensive weather modification is
large the social implications tend to
remain unexplored until a major problem erupts. The Commission feels
strongly this should not be the course
of events in the future. All agencies
engaged in weather modification attempts should give systematic attention to the social implications. It is
essential that funds be allocated for
corollary research in the social sciences as related to weather and climate modification, both deliberate and
inadvertent. This research should embrace the measurement of impacts,
the identification of basic geographic
relationships between human activity
and weather and climate, and the conditions under which decisions about
weather are made.
THE UW
The ramifications to society—and
hence to our legal system—of the
technological capability to order
weather would be enormous. Even a
limited capacity to modify weather
poses legal problems of great complexity. Urgent as these problems may
soon become, uncertainty as to the
scientific capability makes the recommendation of long-range legal solutions impossible at the present time.
23
Nevertheless, the law is already involved with weather modification and
it is necessary to come to grips now
with some aspects of the problems.
The involvement of the law with
weather modification is of two kinds:
the rules governing the responsibilities and liabilities of weather modifiers to other members of the public;
regulation by government. As to
the former, it is premature to make
any recommendations concerning the
rules of law which should be adopted
to govern "property rights in weather,"
or the liabilities of weather modifiers
with respect to those claiming injury
to their persons or property. It is to
be hoped that problems of weather
modification will be decided on their
own merits rather than on the basis
of too facile analogies to the law respecting land, water, wild animals,
airspace, and the like. The few court
decisions to date, while useful in illustrating the kinds of conflicts which
can be expected to arise, do not give
much basis for predicting how the
law will develop. As the law stands,
however, government contractors and
grantees are subject to a risk that
liability will be imposed on them for
damage caused by their activities and
that risk may have an inhibiting effect
on participation in government programs.
As to regulation, some twenty-two
states have enacted laws regulating
weather modification. Most of these
statutes require licenses. One state
prohibits weather modification activities entirely. While these statutes
have had little effect on weather modification activities, there is a distinct
possibility that they may interfere
with desirable Federal programs in
the future.
Until recently the only Federal
"regulation" was the requirement by
the National Science Foundation for
reports on activities already undertaken by operators of whose activities
the Foundation was aware. Effective
January 1, 1966, the Foundation substantially increased its record-keeping
requirements and imposed on all operators a requirement of advance notice to it of any activity.
The present authority of the Foundation under Public Law 85-510 provides for obtaining—by regulation or
otherwise—information, including advance notice of any proposed weather
modification activities, deemed necessary to its program of study, research,
and evaluation. This information is an
aid to the Federal research and devel24
opment effort and to the protection of
its integrity. But, the lack of Federal
authority to stop activities which may
interfere with or contaminate Federally-supported programs renders the
Federal government powerless to protect its programs from the actions of
privately supported parties or state
and local instrumentalities except by
voluntary arrangements.
Thus, the Commission recommends
that the Federal government, by appropriate legislation, be empowered
to:
delay or halt all activities—public or private—in actual or potential
conflict with weather and climate
modification programs of the Federal
Government, whether these programs
are conducted for the Federal government, by its own agencies or by its
grantees or contractors;
immunize Federal agents, grantees, and contractors engaged in
weather and climate modification activities from state and local government interference; and
provide to Federal grantees and
contractors indemnification or other
protection against liability to the public for damages caused by Federal programs of weather and climate modification.
These recommendations are deliberately restricted in scope, in the belief that in the developmental stage of
weather and climate modification the
minimum regulation consistent with
immediate goals is desirable. However, it should be recognized that as
knowledge develops and as weather
and climate modification activities increase, more comprehensive regulation in the public interest may be
required. Such regulation might include setting standards of professional qualifications and financial
responsibility for operators, establishment of appropriate authority for determining which experiments or operations may be undertaken in the public
interest, and a requirement of evaluation of activities by the operator.
Finally, since weather no more respects national boundaries than it does
State lines, it is hoped that early efforts will be made to delineate and
study the international legal problems
of weather and climate modification.
25
NEEDS AND OPPORTUNITIES
FOR INTERNATIONAL COOPERATION
The program of research required
to develop the capability to modify
weather and climate suggest a strong
emphasis upon international cooperation. The extensive and significant
work that is being done in other countries underscores the need for promoting the international exchange of
data and research findings for the purpose of maximizing their usefulness.
The need for international collaboration in the actual planning and conduct of research activities may be
expected to increase as research moves
out of the laboratory and into the
realm of field experiments associated
with the study of the dynamics of
climate, the establishment of a global
weather observation network and the
investigation of other aspects of the
general atmospheric circulation. The
technological and human resources required for the conduct of this type
of research are far beyond the capability of most countries to provide individually.
Looking into the future to the time
when field experiments with weather
or climate modification are expanded
in scope and number and involve actual attempts to introduce changes in
the atmosphere, some form of international collaboration will be essential
in the planning and execution of projects that may have an effect not only
upon the immediate localities but on
areas in other countries and even
upon other continents distant from
the scene of work. It is possible that
situations of this sort may arise in
the near future if an expanded program of field experiments in cloud
seeding is undertaken in areas near
the northern or southern borders of
the United States. An expansion in experimentation with tropical hurricanes may also present international
complications.
In the present stage of world affairs
any scientific advance contributing
significantly to man's ability to affect
the natural environment inevitably
has a bearing upon the political relations among nations and the quest for
peace and security. The importance to
military operations of a capability for
modifying weather conditions is obvious. It must be recognized that there
is a remote possibility that sometime
in the future a nation might develop
the capability to use weather modifi26
cation to inflict damage on the economy and civil population of another
country.
It is essential to develop the political and social controls over the use
of this power which will maximize the
opportunities for its constructive and
peaceful use and minimize the factors
which tend to involve it in the tensions and conflicts inherent in human
society. The challenge and the opportunity which are presented to the
world community by the prospect of
man's achieving a power to modify
his atmospheric environment is one of
the most exciting long-range aspects
of the subject.
Thought must be given to the types
of international organizations that will
be needed, and the functions they
should perform, if and when major
operations in weather and climate
modification affecting large continental areas become feasible. Whether
the assignment of operational responsibility to an international agency
should be considered for the future
deserves thought even at this early
date. Consideration might be given to
new concepts of international organization and to the new problems of a
technical or political nature that
might be precipitated.
The very fact that the development
of a capability for influencing the atmospheric environment is still in its
infancy should widen the opportunity
presented by this scientific endeavor
to develop attitudes and patterns of
collaboration which can contribute
not only to the achievement of the
practical, technological goals, but also
to the relaxation of international tensions.
Rarely has a more ample and inviting opportunity been offered for
advance thinking and planning regarding the impact of a technological
development upon international relations. Progress in the diminution of
international tensions and the achievement of peace will come not so much
from the dramatic resolution of basic
international controversies as from
the far less spectacular widening of
areas of mutual interest among rival
nations and from the growth in ways
of cooperation. The field of weather
and climate modification can serve
well in this regard, in addition to
realizing benefits of a more limited
practical nature.
The Commission believes that:
1. It would be highly desirable for
the Government of the United States,
27
in connection with the expansion of
its program of weather and climate
modification, to issue a basic statement of its views on the relationship
of this national effort to the interests,
hopes, and possible apprehensions of
the rest of the world. Early enunciation of national policy embodying two
main points are recommended:
that it is the purpose of the
United States, with normal and due
regard to its own basic interests, to
pursue its efforts in weather and climate modification for peaceful ends
and for the constructive improvement
of conditions of human life throughout the world; and
that the United States, recognizing the interests and concerns of
other countries, welcomes and solicits
their cooperation, directly and through
international arrangements, for the
mutual achievement of human wellbeing.
This cooperation should cover both
research and, ultimately, operational
programs of interest to other countries. It should be concerned not only
with deliberate, but also inadvertent
human interventions in the atmosphere that affect weather and climate.
Such a policy declaration could be
issued by the President or appropriately incorporated in any basic legislation on the subject of weather modification which the Congress may enact.
Steps should be taken by the
United States, in concert with other
nations, to explore the international
institutional mechanisms that may be
appropriate to foster international cooperation and cope with the problems
which may be anticipated in the field
of weather and climate modification.
The United Nations and its specialized agencies (e.g., the World Meteorological Organization) is suggested as
a possible intergovernmental framework. The International Council of
Scientific Unions and its associated
unions (e.g., the International Union
of Geodesy and Geophysics) could be
a suitable non-governmental framework for these mechanisms.
A major limitation affecting both
advanced and developing countries is
the shortage of trained personnel in
atmospheric sciences at all levels. Attention should be given to the question of how greater emphasis can be
given to atmospheric sciences in existing bilateral and multilateral programs of education and technical
cooperation; and to what additional
measures may be needed to fill this
deficiency.
28
4. Encouragement should be given
to research on the impact of weather
modification measures in foreign
countries. The need has been previously discussed for greater attention
to the biological, economic and social
aspects of weather modification in the
United States. A different set of problems may well be encountered in many
of the developing countries where the
natural environment and patterns of
economic and social life present contrasts to those prevailing in this country. A greater understanding of the
significance of these differences must
precede any attempt to evaluate the
suitability of various weather and climate modification practices for specific foreign areas and to design appropriate programs of cooperation.
FISCAL AND OROANIZATIONAL
CONSIDERATIONS
Scope ano Nature 01 the
National Program
The four principal elements of a
national program for weather and climate modification that appear to be
warranted by the evidence presently
at hand are as follows:
There should be a strengthened
program of fundamental research in
the atmospheric sciences and the initiation of complementary research in
the biological and social sciences. Research in the atmospheric and the
biological sciences should range from
studies of a large and extensive nature
involving many individuals and substantial logistical support to the work
of individual investigators. Desirable
research on socio-economic aspects
and the legal and international implications will generally consist of studies of relatively modest cost.
There should be a concerted effort directed specifically at the development of what may be called the
technology of weather and climate
modification. This is a sector in which
a conspicuous gap is becoming evident. The objectives should be early
development and testing of techniques
by which deliberate intervention in
atmospheric processes can be accomplished and consideration of the
likely consequences of human activity
in inadvertent intervention. Largescale undertakings with substantial
logistical support will be required and
close liaison will be desirable with
29
the social, biological and other related
studies.
There should be provision for
operational application by both the
public and the private sectors as the
feasibility and efficacy of modification techniques are validated.
There should be such regulation
as may be required to protect the
public interest and advance the state
of the art. Admittedly, it is difficult to
arrive at a judgment on such matters
as the timing and necessary scope of
regulation and the form of administration. In the opinion of the Commission, however, it is not too soon to
deal with this matter providing flexibility for adaptation to changing needs.
funding
In the light of the above program,
the following considerations with respect to funding appear to be revelant.
Federal financial support for research and development activities in
weather and climate modification
needs to be increased substantially
above present levels.
Large field observational programs and experiments of both a basic
and an applied nature will be costly.
They will require logistical support of
substantial proportions in the form,
for example, of suitable instrumentation, aircraft, synchronous satellites
and ecological laboratories. Some idea
of the costs for which provision
should be made is given by the estimate that a field experiment on hail
by use of doppler radar and aircraft
would cost at least $2 million a year.
The weather and climate modification program needs a strong centralized group as could be provided by
a national laboratory. Such a group
or center could serve as a focal point
for research and development to conduct and assist in large scale experiments and to provide logistic capabilities. The availability of a center with
its facilities would serve as a nucleus
for program planning and interchange
of scientists on an international basis.
It should be interdisciplinary in character and provide for the conduct and
support of research in those physical,
biological and social sciences which
are involved in weather and climate
modification.
Federal outlays for weather and
climate modification research and development in Fiscal Year 1966 approximate $7.2 million, exclusive of
logistical support provided by the
30
Department of Defense. This sum constitutes about two percent of the expenditures of all Federal agencies for
the atmospheric sciences and meteorological services. The potential importance of weather and climate
modification, its propects for the
future even in the face of remaining
uncertainties in the present state of
the art, and the magnitude of the effort that may be required to resolve
these uncertainties, require substantial funding. The Commission believes
that by 1970 annual funding should be
increased to the neighborhood of $20
to $30 million, including logistics support, or about five percent of the total
for atmospheric sciences and meteorological services. In addition, increases
of the same order will be needed for
underlying basic research, including
funds for items such as large computing facilities. Thus a total increase
of $40 to $50 million per year may
be envisaged by 1970. The level of
funding must, of course, be constantly
reviewed as progress is made.
Organizalional ROSOORM1111183
Weather and climate modification
pervades many facets of human activity; it is natural that several Federal
agencies have been involved as they
fulfill agency missions. In the last full
fiscal year, 1965, the Departments of
Agriculture, Commerce, Defense and
Interior and the National Science
Foundation all expended funds for
weather modification. No single
agency in the Federal government now
has responsibility for developing the
technology of weather and climate
modification. The need for such designation is now, however, becoming
evident.
The future requirements of the
agencies, and the needs of the weather
and climate modification field, suggest
that the organization of a national
program should be unified around one
agency, yet open for the participation
of those agencies whose missions require the conduct or support of
weather and climate modification activities. The national program needs
to provide for agencies such as the
Federal Aviation Agency, which might
operate over an area as small as an
airport, to the State Department with
its concern over the relationship of
weather and climate modification to
foreign policy. Thus, a national program should provide for the diversity
of intellectual interests associated
31
with the subject, field and laboratory
projects both large and small, and a
growth in financial support consistent
with prospective results.
The Commission takes the
position that:
The mission of developing and
testing techniques for modifying
weather and climate should be assigned to an agency in the Executive
Branch of the Federal Governmentfor example, to the Environmental
Science Services Administration of
the Department of Commerce or to a
completely new agency organized for
the purpose. The mission should include support and conduct of research
and development and such operational
activities as are needed for the furtherance of the technology of weather
and climate modification. This agency
should have major but not exclusive
responsibility, in collaboration with
the State Department, for formulating and implementing programs of
weather and climate modification involving international cooperation.
The National Science Foundation
should continue and expand its support of research in the atmospheric
sciences, including its program directed at providing a satisfactory scientific basis for weather and climate
modification. This should be carried
on primarily at universities and colleges and should include maintenance
of the National Center for Atmospheric Research as a facility for the
conduct of basic research on a scale
beyond that feasible for individual
university investigators. The degree
of continuing and special attention
given by the Foundation to the support of the physical sciences, engineering, the biological sciences and
the social sciences aspects of weather
and climate modification should be
reviewed from time to time in the
light of the progress of the over-all
national program.
Federal agencies should undertake such operational activities as
may be required for the effective discharge of their missions (e.g., suppression of lightning by the Forest
Service, fog dispersion by the Federal
Aviation Agency and rainfall augmentation for the reservoir system of the
Department of the Interior). Also,
pursuant to Executive Order 10521,
Federal agencies should be free to
conduct and support such research
and development as may be required
in the discharge of their missions.
32
(4) Insofar as the nature of a regulatory agency is concerned, care must
be taken to ensure access of all agencies to the information generated,
while at the same time keeping regulation organizationally separated from
research and development. For example, were the assignment of regulatory responsibility to be made to the
Secretary of Commerce, provision
should be made that it be exercised
outside those parts of the Department
engaged in the conduct of research and
development relating to weather and
climate modification. Whether the regulatory function needs to be divorced
completely from the operating agencies, or can be assigned to a separate
branch of such an agency, will depend
largely on the extent of activity and
the degree of regulation required.
As to the jurisdiction of a regulatory agency over other Federal agencies, insofar as regulation involves
requirements of notice, reports, licensing of activities, etc., there seem to be
good reasons why all agencies should
be subject thereto. In addition, the
regulatory agency should be given
power to resolve minor conflicts between agencies, such as the timing of
particular experiments.
It must be recognized that because
the social effects will be complex and
because Federal agencies are associated with diverse interest groups there
are likely to be major conflicts in programs. Such conflicts go beyond the
scope of regulation and involve administrative coordination at the highest
level. Their resolution should not be
left to a regulatory agency. The Commission recommends that the Office
of Science and Technology should
consider establishment of a special
mechanism for the coordination of
weather modification policies and programs. Such an entity could not only
serve to resolve conflicts but could
serve to promote unity in policy and
deployment of funds and manpower
with optimum effectiveness.
5. Both the Executive Branch and
the Congress may wish to have available scientific and public policy advice
from a group of knowledgeable people
from outside the Government. This
need might well be met by the appointment of a standing committee in the
National Academy of Sciences in cooperation with the National Academy
of Engineering. The group should include persons with experience in the
physical, biological and social sciences
and engineering.
33
INTRODUCTION
For a review of the present status
and potential of weather and climate
modification, the Commission has depended mainly on the report of the
Panel on Weather and Climate Modification of the National Academy of
Sciences *, the annual reports of the
National Science Foundation, and the
report of Gilman, et al.** Since the
scientific basis has been discussed
thoroughly in these reports, there is
no need to repeat it here. Instead of a
detailed discussion, an attempt is made
here to delineate the problem in its
broadest conceptual framework in
order to describe the probable character of a well balanced plan for future
action.
Consideration of the physical problems involved properly begins with a
brief review of the atmosphere as a
physical system, the dimensions of the
quantities of energy that would be
required to alter atmospheric processes
by the exercise of brute force, and the
nature of the instabilities that might
be exploited to exert meaningful influence within the limits of our ability
to manipulate energy. These problems
are discussed in Section II of this
chapter. A brief summary of some of
the most important conclusions of the
NAS Panel is included in Section III.
Also ircluded in this chapter are brief
discussions in Section IV of some of
the projects on weather modification
research carried out under the National Science Foundation program.
In Section V there is a review of
activities in foreign countries. Finally
in Section VI a discussion is given in
broad terms of prospects for future
research.
THE NATURE OF THE
SCIENTIFIC PROBLEM
The atmospheric envelope rotates
with the earth, but does not rest
quietly upon it. Air motion relative to
the earth is induced by a non-uniform
distribution of energy sources and
sinks which are strongly influenced by
those motions which they produce.
* Weather and Climate ModificationProblems and Prospects, Vols. I and II, National Academy of Sciences-National Research Council, 1966 (NAS-NRC 1350).
** Weather and Climate Modification, A
Report to the Chief, United States Weather
Bureau, July, 1965. (Both these reports include extensive bibliographies.)
PROORESS
AND
PROSPECTS
IN WEATHER
AND CLIMATE
MOFICATION
34
The motions themselves range in size
over a spectrum that extends from the
scale of planetary wave systems down
to molecular movement. The sources
and sinks of energy are variable in
number and strength and exist mainly
in response to the disposition of shortwave solar radiation, the flux of outgoing long-wave radiation, the latent
heat involved in the phase change of
water and on the flow of sensible heat
between the lower atmosphere and the
underlying ocean or land. The kinetic
energy of air motion is continuously
exchanged with other forms of energy
in the atmosphere and the kinetic
energy of the several scales of atmospheric is continuously being transferred from one scale to another.
For the purpose at hand, the atmosphere may be viewed as a complex
physical system in which ascertainable changes in air motion take place
in response to identifiable forces. In
principle, by altering these forces, consequent changes in the air motion can
be influenced. Thus, in principle, controlling the weather or modifying
the climate is scientifically possible.
Whether or not it is practically realizable depends on a demonstration of
the capability to alter these forces in
a manner which will produce predictable consequences. To be intellectually satisfying, the cause and effect
relationship would have to be understood in precise and exact detail. To
be meaningful in a practical sense, it is
only necessary to establish beyond a
reasonable doubt that the cause and
effect are related.
It is useful to consider the order
of magnitude of the kinetic energy
involved in several scales of atmospheric subsystems. Some idea may be
obtained from the following table:
Approximate*
Subsystems Energy in ergs
Tornado funnel 1021
Small thunderstorm 1022
Large thunderstorm 1028
1025
Atmospheric �
Hurricane
Extratropical cyclone 1026
General Circulation in the
Northern Hemisphere 5x1027
* Data for the tornado funnel and thunderstorms refer to a total lifetime of kinetic
energy. Data for the other phenomena refer
to kinetic energy at any given moment during
maturity—which may be considerably less
than the lifetime expenditure.
An appreciation of the energy requirements necessary were the kinetic
energy of these atmospheric subsystems to be changed by 10 percent can
be obtained from the next table. The
column on the right lists the time
35
demand on the total electrical energy
generating system of the United States
if that source were to be drawn upon
to change the kinetic energy of the
atmospheric subsystem by ten percent.
Atmospheric � Approxima te *
Subsystem� Time
Tornado 30 seconds
Small thunderstorm 5 minutes
Large thunderstorm several hours
Hurricane several days
Extratropical cyclone 5-6 weeks
General circulation in the
Northern Hemisphere 6 years
* Data for the tornado funnel and thunderstorms refer to a total lifetime of kinetic
energy. Data for the other phenomena refer
to kinetic energy at any given moment during
maturity—which may be considerably less
than the lifetime expenditure.
One concludes that it is not immediately practicable to think of altering
these atmospheric subsystems to this
extent by a direct application of
energy. Nor is it reasonable to think
of using energy directly to alter rainfall. For example, the additional latent
heat released by an increase of 10 percent in a rainfall totaling one inch
over an area one hundred miles on a
side would be the equivalent of about
six days of the daily output of the
electrical generating capacity of the
United States. On the other hand, as
will be seen presently, there exists
some evidence that increases in rainfall of this order may be obtained by
seeding. A triggering mechanism based
on an atmospheric instability is involved. It is appropriate, then, to consider the question of possible instabilities in the atmosphere.
From simple observations of the life
cycle of cumulus clouds, thunderstorms, tornadoes, hurricanes, and
extratropical cyclones, it is evident
that—within certain limits—the atmosphere is unstable, that is, the amplitude of disturbance increases with
time over a period of time which
varies with the size of the disturbance.
Moreover, significant energy transformations are involved in the amplitude
growth associated with these releases
of energy initially in unstable form.
At least four kinds of instability have
been identified as potentially susceptible to man's efforts to trigger natural
reactions. They are:
1. The phase instability of water
in the vapor phase in a condition of supersaturation and in
the liquid phase in the condition of supercooling which,
when released, provides a local
source of sensible heat.
36
The colloidal instability of
cloud particles which when
released by precipitation, completes the cycle by which latent
heat is exchanged between the
underlying surface and the
atmosphere.
The convective instability of
the atmosphere which, when
released, redistributes sensible
energy in the vertical and often
produces high local concentrations of kinetic and electrical
energy.
The baroclinic instability of
the large scale circulation
which, when released, redistribute sensible and kinetic
energy in the horizontal plane,
i.e., from pole to equator.
The results of preliminary experimentation with the first three instabilities identified above lend support to
the point of view that they may be the
"Achilles' Heel" in the atmospheric
system by which large effects might be
produced by relatively modest, but
highly selective, interventions. The
difficulties of treating quantitatively
the non-linear processes inherent in
instabilities are sobering. Some offset
is provided, however, by the indications that energy can progress upward
through the several scales of exchange.
It is pointed out in Volume II of the
NAS Panel report that:
The release of phase instability in an aggregation of supercooled cloud drops can simultaneously colloidally destabilize
the cloud into precipitation
(through the Bergeron-Findeisen mechanism) and, through
the introduction of latent heat
of fusion, convectively destabilize the volume of air within
which the phase change is occurring. All of this has been
observed, on a very small scale,
in the seeding of stratocumulus
clouds. It is not hard to imagine
that induced convection or
induced snowfall on a much
larger scale could sufficiently
alter the horizontal temperature
distribution to trigger or subdue
baroclinic instability, changing
the natural development of
large cyclonic storms. This, in
turn, might alter the global radiation balance and thus influence a fifth scale of instability
37
about which we can only conjecture: the possible instability
of global climate.
The great variability of ancient climates is accepted as
fact, yet the cause of climatic
change is far from being a settled issue. It is obvious that the
earth-atmosphere system can
support radically different climatic regimes, some of which
could be disastrous to civilization. We do not yet know what
can cause a shift from one
climatic regime to another,
whether change can occur in an
"instant" of geologic time or
only as a secular, cyclic process; our few theories still hang
on the most tenuous of evidence.
This, in barest outline, is the nature
of the problem and some of its implications. It is appropriate now to turn
to some advances in recent years that
suggest the present moment to be a
propitious one to accelerate and
strengthen the systematic exploration
of the question.
PRESENT STATUS OF
WEATHER MODIFICATION
The reports cited in the Introduction
to this chapter give excellent discussions of the present status and promise of weather and climate modification.
A brief summary of some of the
more important findings is given here.
Some aspects of weather and climate
modification are ready for practical
applications, others are sufficiently
promising to warrant programs of
mission-oriented or applied research,
still others are more remote possibilities for which no more than basic research can be justified at the present
time. Furthest advanced is the problem of dissipation of supercooled fog
and stratus clouds by seeding, which
has reached the stage of engineering
applications for clearing of fog at airports. Experiments done here and
abroad on cloud seeding for local increase of precipitation and for suppression of hail and of lightning, while
far from conclusive, have shown some
promise of success. Vigorous programs of applied research should be
pursued in these areas to delineate the
38
potential and to optimize the procedures used.
Without many more years of basic
research on large-scale circulations of
the atmosphere and the causes of climatic change, no program of modification of climate extending over large
areas of the earth's surface could or
should be undertaken. Such a research
program, although difficult and expensive, can be justified for aid in longrange forecasting and for making possible predictions of consequences of
inadvertent changes in the atmosphere caused by activities of man. The
possibility that such a program will in
the future suggest methods for beneficial modification of climate is added
incentive for undertaking it.
Given below is a brief summary of
some of the main conclusions of the
reports on the present status of
weather modification. A review is then
given of some of the research programs on weather modification undertaken during the past few years both
here and abroad. The summary is necessarily quite brief; the reader is referred to the reports cited for detailed
information and background.
clearing of Supercooled
SIMUS and Fog
Effects of seeding by dry ice and by
silver iodide were first demonstrated
upon supercooled stratiform clouds.
Recently attempts have been made to
develop operational methods for clearing of supercooled fog at airports.
Such methods have been used here
and abroad for the past several years,
particularly in the USSR, where the
problem is more severe. Clearing of
warm fog is much more difficult and
no really satisfactory methods have
been proposed.
Increase of tocai Precipitation
uY seeding
It has long been controversial as to
whether local precipitation can be
enhanced by seeding. The NAS Panel
has made a statistical study of commercial seeding operations mostly
using ground-based silver iodide generators. Included were operations in
the Eastern U.S. and in orographic
situations in the Western U.S. In addition, preliminary results of several
39
randomized experiments on seeding
both in this country and abroad have
become available during the past year
and are included in the study. In Volume I of the NAS Panel report it is
stated: "There is increasing but still
somewhat ambiguous statistical evidence that precipitation from some
types of cloud and storm systems can
be modestly increased or redistributed by seeding techniques. The implications are manifold and of immediate national concern." The statement
cannot be made more conclusive because of the possibility of some unknown source of bias or systematic
error in the commercial seeding operations and because chance fluctuations
cannot be completely ruled out as an
explanation of the more limited randomized tests. It should be emphasized that the problem is an extremely
complex one; there is great variability
in cloud types and in ways in which
precipitation can occur. The theoretical knowledge of how seeding nuclei
are introduced into clouds from
ground-based generators and how precipitation may be affected thereby is
still quite rudimentary.
Present indications, if taken at face
value, are that local precipitation can
be increased in many situations in the
order of io% by seeding. These positive results are obtained in cases
where rain would have fallen anyway
without seeding; there is no evidence
that seeding can induce rain to fall
when normally there would be none.
Thus, seeding is of limited value in
relieving drought situations.
There is very tenuous evidence that
there may be under certain circumstances a "rain shadow" effect, an
area of decreased precipitation downwind from the area of enhancement.
There is no reason to suspect that this
might be caused by "rain out" of available moisture, since normally only a
fraction is released as rain in any case.
Theoretically, one could have considerable enhancement of local rainfall
without appreciable influence on precipitation further downwind.
rncrease ol rreciniiahoo
by FORM COUVOCHOR
Suggestions have been made that precipitation in some local areas could
be increased by changes in the earth's
surface to promote great absorption
of heat and also greater transfer of
heat and water vapor to the atmos40
phere. This would stimulate convection; hopefully in sufficient amount to
increase cloudiness and precipitation
downwind. While some plans have
been formulated, no field tests have
been made to test this proposal. Another method, which has given some
indications of success in limited trials,
makes use of seeding. It has been sug
gested that latent heat released by increased condensation of moisture into
water droplets causes uplift and cloud
formation. It may be that some of the
observed increases in precipitation by
cloud seeding result from enhanced
convection rather than directly by
nucleation of droplets.
LWIIIAIDO suppression
Studies carried out under Project Skyfire of the U. S. Forest Service for the
past several years have given indications that seeding can alter cloud to
ground lightning from thunderclouds.
Background has been developed for a
more thorough statistical study to see
under what conditions seeding may
be effective in reducing lightning and
lightning-caused forest fires. Another
suggestion, not yet tested on a large
scale, is to introduce chaff (metallized
strips) into clouds to decrease electric
field gradients.
Hall Suppression
Studies of suppression of hail by seeding or other techniques have mostly
been carried out abroad and with inconclusive results. There are reports
that Soviet scientists by introducing
seeding nuclei at the optimum position and time by use of antiaircraft
shells have had success, but this work
has not been duplicated in this country. Volume I of the NAS Panel report
states that "the U. S. hail research
program is piecemeal and clearly of
sub-critical size." Plans are underway
by the National Science Foundation
to initiate a program in this area.
Mofleratiog severe siorms,
IND TornaOoes, and Hurricanes
Under Project Stormfury, several attempts have been made to modify
hurricanes by seeding. The intent is
to produce warming in the outer zone
of the eye wall by releasing latent
heat of fusion and so alter the pres41
sure and wind distributions. Results
are so far inconclusive. Progress in
these areas, where tremendous energies are involved, will require much
further basic research involving extensive field investigations and development of theoretical models.
mominu me microcumaie
01 flauls
The problems are largely concerned
with means for preventing frost, for
suppressing evaporation and for reducing effects of wind. Practical methods have been in use for long periods
of time; there has been limited application of modern knowledge of micrometeorology to optimize procedures.
Further research on boundary-layer
energy and moisture exchange is highly
desirable.
Laroe-scaie MoOiticallon
01 cumaie
The possibilities of making use of instabilities in the atmosphere to alter
the climate of large regions of the
earth's surface will be discussed in
more detail later in this chapter.
Nimmons 01 comaie
For the future welfare of mankind it
is important to be able to understand
the factors involved in climatic change
and thus to be able to predict inadvertent changes in weather and climate produced by present and future
activities of man. Some beginnings in
this direction are included in the NAS
Panel report. One is an attempt to
assess consequences of the increasing
carbon dioxide content of the atmosphere caused by the burning of fossil
fuels. It is estimated that the CO2 concentration in the atmosphere has increased 10 to 15% in this century,
making significant changes in the heat
balance. The report states that "the
implications of this upon tropospheric
stability cannot be ignored" and that
there is need for continuous monitoring of CO2 content and of simulation
of CO2 effects "using the most sophisticated atmospheric models and numerical computers available" to assess
the consequences. Another important
problem is to determine effects of
urbanization both on local climate and
possible indirect effects which may
extend over much larger areas. Thus
far there has been but little research
on this problem. Effects produced by
altering the rural landscape (agriculture, deforestation, etc.) appear to be
less serious. Other problems considered in the NAS Panel report are possible effects of increase in water vapor
content of the stratosphere by supersonic transport aircraft and of contamination of the higher atmosphere
by rocket exhaust. The report concludes that at present these are not
serious problems. With increasing
technology and population growth,
problems associated with inadvertent
changes in environment will become
even more important in the future.
ACCOMPLISHMENTS OF THE
NATIONAL SCIENCE FOUNOATION
PROGRAM
In order to put the problems of
weather modification in perspective
and to see what has been accomplished in the intervening years, it is
of interest to compare our present
knowledge with that which existed in
1957 at the time of the final report of
the Advisory Committee on Weather
Control. It should be recognized, how
ever, that the 1957 report is concerned
primarily with effects of cloud seeding while we are now considering
weather and climate modification from
a much broader point of view, including inadvertent effects of man-made
activities as well as deliberate attempts to modify the weather.
Relying mainly on analysis of results of commercial seeding operations, the Advisory Committee on
Weather Control reached the following conclusions:
The statistical procedures employed indicated that the seeding of
winter-type storm clouds in mountainous areas in western United
States produced an average increase
in precipitation of 10 to 15 per cent
from seeded storms with heavy
odds that this increase was not the
result of natural variations in the
amount of rainfall.
In nonmountainous areas, the
same statistical procedures did not
detect any increase in precipitation
that could be attributed to cloud
seeding. This does not mean that
effects may not have been produced.
The greater variability of rainfall
patterns in nonmountainous areas
made the techniques less sensitive
43
for picking up small changes which
might have occurred there than
when applied to the mountainous
regions.
No evidence was found in the
evaluation of any project which was
intended to increase precipitation
that cloud seeding had produced a
detectable negative effect on precipitation.
Available hail frequency data
were completely inadequate for
evaluation purposes and no conclusions as to the effectiveness of hail
suppression projects could be
reached.
Conclusion (1) was later severely
criticized as being based on inadequate statistical evidence and lack of
adequate controls, but present indications are that it is probably correct.
Evidence presented in the NAS Panel
report suggests that seeding in some
cases may enhance local precipitation
even in nonmountainous areas by
similar amounts. There is some rather
tenuous evidence of a shadow zone of
decreased precipitation beyond the
area of local enhancement. Thus conclusions (2) and (3) no longer appear
to be valid. A current statement concerning the status of hail suppression
could not be made much more definite
then conclusion (4).
The Advisory Committee on
Weather Control report recommended
an increase in research in meteorology
and related fields; that the National
Science Foundation be the agency
designated to promote and support
such research and to be "a central
point for the assembly, evaluation, and
dissemination of information and that
the development in large numbers of
highly qualified research scientists in
the field is essential. The report also
emphasized basic research leading to
a scientific understanding of weather,
with the aim in part of putting cloud
seeding on a firmer scientific basis. In
1957 there were few professional peopie working on scientific aspects of
weather modification. As a result of
subsequent activities and support of
the Foundation and other agencies,
there are now involved a number of
outstanding groups in universities,
government, and industry. Among the
universities that have groups engaged
in research related to cloud physics
and weather modification are Arizona,
Chicago, Colorado State, New Mexico
Institute of Mining, Nevada, New
York University, Pennsylvania State,
State University of New York, and the
44
University of Washington. The Program of the Illinois State Water Survey is partially supported by the
State. An outline of the programs of
various government agencies is given
in this report in the chapter on Funding and Administration Requirements.
Several industrial organizations such
as A. D. Little, Inc. have research programs on various aspects of weather
modification. There are of the order of
40 to 50 concerns engaged in commercial seeding operations.
While a great deal has been learned
about the physics of clouds and the
precipitation process, because of the
extreme complexity of the problem
there is still far from a scientific understanding of effects of cloud seeding and the dynamics of clouds. A
brief review of a few of the major
projects sponsored in whole or in part
by the Foundation may be in order:
(1) One of the most important is
the University of Chicago "Project
Whitetop" which has demonstrated
the importance of the warm rain
coalescence process in many supercooled convective cloud systems
which formerly were thought to depend entirely on the Bergeron-Findeisen ice process. A preliminary analysis of a cloud seeding program extending over a five year period at
West Plains, Missouri, indicates a region of increased radar precipitation
echo extending 30-50 miles downwind
of the seeding line followed by a
broad region further downwind with
decreased precipitation. This precipitation pattern was detected by radar
echoes and supported in part by rain
gauge data. These data suggest that
seeding may produce a growth of
clouds along the seeding line which
sets up a stationary wave-like perturbation extending downstream. In the
region 40-80 miles downstream the
air is sinking rather than rising and so
is unfavorable for cloud growth. Thus,
the shadow zone of decreased precipitation may result indirectly from a
dynamical effect rather than from
prior rainout of available moisture.
(2) For the past ten years, the Kings
River Conservation District has supported a cloud seeding program by
Atmospherics, Inc. in the Kings River
Drainage area on the Western slopes
of the Sierra Nevada Range in California. A grant from the Foundation
provided for additional measurements
for study of cloud physics and precipitation. Recent analysis of the data
indicates an average 6.1 % increase in
runoff in the drainage area due to
45
seeding for the period. This supports
preliminary results of a research
study by Colorado State University in
the area of Climax, Colorado, and of
other commercial seeding operations,
extending over shorter periods of
time, that seeding can give a moderate
increase in precipitation in orographic
situations. An analysis of these and
other seeding experiments is included
in the NAS Panel report.
(3) Project Stormfury, a joint
Weather Bureau-Navy project, with
support from the Foundation, is an
attempt to modify tropical clouds and
perhaps hurricanes by massive seeding. The idea here is to enhance cloud
buoyancy and thus later cloud dynamics by release of latent heat of fusion.
Conclusive results have not yet been
obtained, although there is considerable evidence that clouds can be modified in this way. Howell, in 1960, presented data on effects of seeding of
tropical cumuli which indicated enhanced buoyancy and a consequent
increase of precipitation. A group at
Pennsylvania State University has
been investigating the possibility of
providing positive buoyancy to clouds
in the lee wave of mountain systems
by seeding.
A great deal has been learned
from laboratory studies about the nucleation process with AgI as well as
with other materials; however, much
remains to be done in correlating
such laboratory work with effects
produced by various practical seeding
methods.
Considerable progress has been
made in studies of clearing of supercooled stratus and fog by seeding. The
problem of dissipation of supercooled
fog over airports is now largely one of
design of suitable seeding devices. It
has been suggested that because of
their stability and consequent reproducibility of results, supercooled stratus clouds could be used for testing of
seeding agents.
Studies are being made of electric fields in clouds, their possible influence on the precipitation mechanism and of methods for changing the
electric field patterns as a possible
technique for modification of clouds.
Much of the activity since 1957, and
particularly that under Foundation
sponsorship has been aimed at basic
scientific understanding. In complex
problems this is a sound if often slow,
way of arriving at practical goals.
With a sufficiently thorough under46
standing one should be able to estimate both the possibilities and limitations of various techniques. At the
other extreme are the purely empirical
methods of trying various procedures
and observing the overall results without worrying too much about the detailed mechanisms of how and why
they occur. In cases where there is a
great deal of natural variability, one
must rely on sound statistical methods with adequate controls. Unfortunately many of the empirical studies
of the past for one reason or another
did not yield conclusive results. The
empirical and basic approaches are
both valuable and complement one
another. Empirical discoveries may
stimulate basic research and lead to
new understanding. Scientific understanding, even though far from complete, may suggest new or modified
empirical approaches.
The problems involved in statistical
design of experiments are discussed
in this report in the chapter on Statistical Aspects of Weather Modification.
ACTIVITIES IN FOREIIIN COUNTRIES
The achievement in artificial nucleation by Schaefer, Langmuir and Vonnegut in 1946-47 had repercussions
throughout the world. Within a few
years weather modification activities
had been initiated in a number of
countries. In its Third Annual Report
on Weather Modification for FY 1961
the National Science Foundation gave
data on work underway in sixteen
countries.' More than 100 research
stations outside of the United States
were reported as being engaged in
weather modification work. As in the
United States, a major emphasis in
most foreign countries has been placed
upon cloud seeding or other efforts at
rainmaking. Considerable attention in
some countries has been given to fog
dissipation and hail suppression,
while significant basic scientific research programs have been undertaken
in several lands.
Australia, faced with growing demands for water, both for agriculture
and hydroelectric power, has undertaken significant programs of basic research in cloud physics as well as
large scale field experiments in cloud
seeding. A variety of cloud-seeding
experiments has been carried out in
Canada by both government and private agencies since 1948. France has
established a broad program of scientific research coupled with practical
47
experiments. Ten different organizations are engaged in French weather
modification programs; in addition to
fundamental research, special interest
has been displayed in hail prevention
and fog dispersal. Laboratory research
has been featured in Germany, where
weather modification activities were
late in getting underway. Interest in
Great Britain has also been directed
almost exclusively at basic research
in cloud physics, cloud dynamics and
atmospheric electricity.
A special concern with the practical problem of hail suppression has
characterized the weather modification work in Switzerland. The Federal
Commission for Studying Hail Formation and Hail Prevention, established
in 1950, operates three laboratories
which have contributed significant
knowledge to the understanding of
hail formation and have carried out a
variety of experiments in cloud seeding as a means of prevention. Similar
concern with urgent national problems has been noted in the development of weather modification work in
Israel, where water supplies are of
paramount importance to the economy; a broad program of research and
field experimentation has been directed at the investigation of the natural processes of rain formation and
their possible manipulation by artificial means. An active program of both
basic research and empirical studies
of cloud seeding has been pursued in
Japan. Some success has been reported in seeding programs. In 1964
an International Conference on Cloud
Physics was held in Japan.
Of particular importance in the
work going on in foreign countries is
that being carried forward in the Soviet Union. Faced with a number of
serious problems created by a hostile
natural environment affecting the economic welfare of the country, the Soviet Union has shown an active and
intensive interest in the subjects of
weather and climate modification. The
delegation of the U. S. Weather Bureau which visited the Soviet Union
in May, 1964, returning a similar visit
to the United States by Soviet scientists earlier that year, was particularly
impressed by the broad scope of the
Soviet program and the large resources of manpower and funds that
were being concentrated on weather
modification and related activities. Although actual work is undertaken in
a number of institutes located in various parts of the Soviet Union, and
includes activities in both the Arctic
48
and Antarctic, the Soviet activities appear to be well integrated into a national program and guided towards the
achievement of objectives directly related to the economic and social needs
of the country.
Among the Soviet Union's theoretical studies, emphasis has been placed
upon research in cloud physics at
numerous centers, as well as upon
theoretical evaluations of the possibilities of climate modification. Indicative of the broad dimensions and
imaginative character of Soviet thinking have been speculative suggestions
of climate modification by erection of
major hydraulic structures which
would alter ocean currents, artificially
inducing changes in snow cover, producing changes in cloud cover by
seeding, and altering the surface to
induce lifting or subsidence of air.
One of the most spectacular is the
suggestion of damming the Bearing
Straits.
Field experiments have concentrated upon three areas of common
concern to many other countries: dissipation of fog and low stratus clouds,
particularly over airports; suppression of hail; and rainmaking. While
statistical tests have generally not
been undertaken, many Soviet scientists are convinced the empirical evidence is sufficient to support their
claims of success. Such claims include
statements that the dissipation of supercooled fog and low stratus over
airports has now become operational;
that cloud seeding can increase precipitation from frontal clouds by
around ten per cent; and that the possibility has been demonstrated of
greatly decreasing the formation of
large, damaging hail. Considerable
benefit has apparently been derived
by Soviet scientists from work done
in the United States and other countries as a result of the thorough and
extensive program of review and
translation of scientific literature—an
aspect of research some American scientists believe could well be expanded
in this country.
The resume given above of some of
the major weather modification activities in foreign countries is by no
means a complete inventory. Other
work is being initiated and carried
forward in several other countries.
The wide distribution of activity in
this field throughout the world is in
one sense a reflection of the essentially international character of science. It is also an indication of the
growing realization by scientists, and
49
by governments, that the possibility
of weather and climate modification
may have profound repercussions
upon the future economic and social
welfare of their countries.
PERSPECTIVES FOR RESEARCH
It is recognized that several interrelated branches of earth science must
be developed as a foundation for the
technology of environmental control.
These include study of the mechanisms and energy balances involved in
the hydrologic cycle, development of
further understanding of the dynamics
of climate through atmospheric modeling and computational experiments
including weather prediction, broadening both field and laboratory research in cloud physics and dynamics,
and a thorough examination of the
non-atmospheric mechanisms, such as
modification of the surface characteristics of the land and sea, which might
conceivably alter weather or climate.
Each of these will be discussed in
turn.
Hydrologic Cycle
The words Weather Modification
have come, through usage, to mean
the conscious intervention by man in
the precipitation process; either its
augmentation or reduction and ultimately its control. In this view attention is centered on the atmosphere.
But weather is only a link in the
hydrologic cycle in which water,
through various energy exchanges, is
distilled from the oceans or transpired
from the ground water table into the
atmosphere, is stored in the atmosphere for a time, and eventually returned to earth in another place.
In principle, effective practice of
weather and climate modification may
consist of activities which produce
alterations at any point in the hydrologic cycle that could conceivably lead
to control of persistent or momentary
extremes. Since the global water cycle
is a closed but multiply-connected
loop (much like the cardiovascular
system) the consequences or effectiveness of intervention may either be
"healed" by self-regulatory processes
which give the hydrological system
its stability, or lead to systematic
change.
50
The problem of weather and climate
modification, then, requires sufficiently
detailed understanding of the energy
transformations of the hydrologic
cycle to know where, how, when, and
with what intensity man's intervention in the natural system may produce significant alterations. Effective
pursuit of this understanding will require the concerted knowledge and
skills of geologists, hydrologists,
oceanographers, meteorologists, engineers, and the close support of those
versed in applied physics, mathematics, ecology, and chemistry. As
yet this breadth of enterprise has
neither been reached nor contemplated.
In the present state of knowledge
atmospheric intervention seems to
offer a promising point at which to
exert an influence upon the hydrologic cycle in the interests of mankind. However, as knowledge is advanced in other areas of the earth
sciences, particularly in oceanography, it is possible that other and perhaps even more promising alternatives
may come to light.
Dynamics 01 Climale
In the various aspects of the weather
modification problem thought has been
centered around the issues of water
resources particularly in those areas
where there is a shortage of supply.
This is a natural concern because it
is one ultimate goal of the weather
and climate modification concept to
regulate, if not increase, the availability of potable water for the uses of
mankind. In consideration of this goal,
it is necessary to think not of times
and localities where the need for
water is most sorely felt, but of the
dynamics of climate over the whole
earth in which the dry areas have
context.
Since precipitation in the free air is
associated with the rise and adiabatic
cooling of moist air, the processes to
be encouraged must be those which
will induce rising motion, especially
of maritime air over regions presently
deficient in rainfall. Rising air occurs
in three principal situations: in cumulus convection (micro to macro scale),
in orographic lifting (meso to macro
scale) and in frontal lifting (macro
scale). Once initiated, lifting may be
encouraged by energy releases asso51
ciated with phase changes in the water
burden of the atmosphere. Lifting may
also be encouraged by physical or
thermal topographic influences on the
earth's surface.
In regions where an excess of precipitation exists it might also be desirable to suppress rising motions of
air. The mechanisms governing sinking motions are not yet clear and must
be understood before regional weather
modification can be contemplated.
Rising and sinking motions in the
general circulation of the atmosphere
tend to be arranged in zonal patterns,
hence climates of the earth also tend
to be developed in zones. The nonzonal irregularities in the arrangement
of climatic belts on the earth are found
in the transition regions between land
and sea, because heating air flow is
predominantly zonal while the distribution of land is more nearly meridional.
In the atmosphere, as it is now constituted, there are belts of rising and
sinking air the emerge with statistical
significance. In the intertropical convergence near the geographic equator
rising motions occur and cumulus convection is the principal mechanism
for the release of precipitation. In the
subtropical zones near 300 latitude,
the desert belt in each hemisphere,
sinking predominates and there is a
consequent excess of evaporation over
precipitation owing to the adiabatic
heating of the descending air. In high
middle latitudes frontal lifting is the
predominant mechanism promoting
the development of stratiform clouds
from which precipitation may occur.
Local anomalies in this general pattern are developed by orographic influences and surface effects. Effective
weather regulation would rearrange
the geographic limits within which
these statistically predominant zonal
configurations of rainfall and evaporation now occur.
A problem of this magnitude requires study of the susceptibility of
the atmosphere to change by systematic influences. It is already well known
that the atmosphere responds as a
whole to disturbances within any part
of it. It is also known that the atmosphere exhibits a kind of statistical
stability. If it did not, the subject of
climatology could not be pursued. One
has, therefore, to learn through an intensive series of computer simulation
experiments and quantitative laboratory investigations with rotating models where, how forcefully and how
often the atmosphere must be dis52
turbed to change the statistics of climatology. The question at this point
should be addressed to a study of
changes of all kinds. Once the effects
and energy requirements for intervention are known from laboratory and
numerical studies, it would then be
possible to select certain changes as
a basis for field experimentation. It
would also be known how massive
such undertakings in the field might
have to be to produce effects that
emerge clearly above the normal levels
of atmospheric variability.
One would hope that model experiments will divulge the type of
instabilities that can be seized upon
to swing a climate regime in a
particular direction. If it becomes
evident that the atmosphere only
marginally sustains a particular phenomenon; for example, if it appears
that hurricanes are not an essential
element of the general circulation,
then perhaps one can accomplish
the corresponding heat flux entirely
by a related phenomenon which is
more prevalent, i.e. weakly organized convection. Speculating on a
much larger time scale: is the occurrence of an ice age or the formation of a large desert an inexorable
necessity or are they the consequence of weak but systematic
interactions which may easily be
disrupted once we learn what the
critically participating processes
are?*
A program of this kind is bound to
involve a considerable expansion of
effort and facilities. For example, the
computational effort required is
roughly two orders of magnitude
greater than that possible with the
largest machine now in existence. The
suitable equipment for laboratory research in rotating models might also
cause an expansion of effort by a factor of two or three over the present
level. Still, the hope would be that
this kind of undertaking could be
accomplished with only moderately
increased resources of manpower,
through student training and the attraction of foreign scientists into this
sphere of activity. Since the atmospheric, oceanographic and geologic
properties of the whole earth are to
be considered, there would be a natural basis for international cooperation.
* Smagorinsky, J. 1964 statement at the
National Science Foundation Interagency
Conference on Weather Modification, Washington, D. C., 5-6 November 1965.
53
Prediction
Useful as control might be in
weather management, prediction can
serve an almost equally valuable social
and economic function. Accurate prediction is possible only when there is
virtually complete physical understanding of the processes interacting
to produce change. Prediction also
requires a very complete description
of initial conditions; which is to say
it will soon be necessary to establish
a global network of observatories
across the land and sea areas of the
whole earth to fill out the significance
of satellite reports. Steps toward this
end are already being taken in connection with the World Weather
Watch, but consideration of the corresponding networks needed to determine the fluxes of heat, mass and
momentum within the oceans and between the oceans and atmosphere is
not yet so far advanced. The related
technological problems of sensing,
telemetry and maintenance of field
equipment in a global network have
not even been defined. However, were
surface and upper air observations to
be available on a global basis the
means for their analysis are even now
becoming well established. And with
their continued development, computers may be expected to have reached
the necessary levels of storage capacity and speed within a decade. Having
this much so close at hand it would
seem appropriate that the scientific
and engineering aspects of a global observation network be given immediate
attention.
cloud Physics and Dynamics
The problem of weather and climate
modification is basically centered on
finding procedures by which man may
intervene with relatively low expenditures of power to achieve detectable
alterations of the atmospheric regimen, and of coupling that power to
the atmosphere in efficient ways. In
present cloud seeding practices a point
or line source of material is diffused
into a significantly large volume of air
by atmospheric turbulence. The disturbance produced in the air feeds on
the energy of phase changes in the
water substance in the atmosphere,
and with consequent conversions of
latent to sensible heat, presumably
alters the buoyancy of air parcels to
excite or amplify vertical motion and
54
the further exchange of sensible and
latent heat until the point of detectable returns has been passed.
Some recent experiments suggest
that beyond the site where precipitation is excited by silver iodide nucleation there is a "rain shadow" which
in itself suggests that wave-like effects
are involved. This finding may have
revealed a useful principle.
It is a relatively common observation that there are many kinds of quasiperiodic wave motions in the atmosphere. Cloud streets are often seen,
lenticular clouds stand in trains in the
lee of mountains, long cumulus trains
develop downwind of ocean islands,
cyclonic storms develop in families
along fronts, and fronts themselves
have conspicuously wave-like characteristics.
As a beginning it would seem desirable that cloud seeding experiments
be extended to include study of the
plume of dynamical consequences
downwind, with an eye to the possibility that resonances might be excited if the phase of successive interventions were correctly placed in
space and time, and conversely that
damping could be managed if the
points of excitation were deliberately
placed out of phase. In this way the
effects of intervention might be amplified enough to be detectable beyond
the present screen of statistics, and at
the same time, means developed to
control the area of influence.
In parallel with this thought, there
is, as yet, very little understanding of
the natural processes by which water
vapor condenses to form cloud droplets, of how such droplets coalesce to
form precipitable entities, or how the
additions of seeding nuclei alter the
natural process. We suggest that along
with that necessary study it may be
well to acknowledge that the earth
supports a pronounced electric potential gradient which is changed in certain storm conditions. Since it is well
known that the coalescence of spraying jets is markedly influenced by the
presence of an electric field far weaker
than many of these, it seems only reasonable to encourage deeper study of
electrical relationships in the atmosphere. Causality is not the question,
but rather the interdependence or coexistence of electric fields and coalescence phenomena that needs examination, with the prospect that through
deliberate atmospheric electrification
some control of the coalescence process may be exercised.
55
The field of cloud physics and dynamics must be developed far beyond
its present state if weather and climate
modification is to become a matter of
practical concern. The questions of
droplet formation and growth of precipitable elements in the dynamics of
clouds need examination on a broader
base than the present level of effort
or varieties of research can supply.
Achievement of this state of understanding will require the best efforts
of those versed in surface physics and
chemistry in addition to physical and
dynamical meterology and possibly
also in acoustics, electrostatics and
dynamics, and high energy optics. As
funding is increased for weather and
climate modification early priorities of
expenditure should be accorded the
development of cloud physics and
dynamics as a necessary basis for
sound technology.
Non-Almospheric Inlervenflon
The atmosphere is underlain by solid
earth and broad expanses of sea water
and responds to their influences. The
effects on the atmosphere of seasonally differential heating and cooling
of the solid earth and oceans produce
monsoonal winds and rains on all subtropical continents, govern the curvatures of the polar fronts and the
courses of both tropical and extratropical cyclones. The oceans provide
the atmosphere with most of its moisture, and because of their large thermal
inertia tend to hold fast the maritime
centers of high and low surface pressure, and thus fix the patterns of
world climate.
The natural scale of oceanic features is large indeed, but through
liquid-filled rotating models many of
their physical aspects can be studied
in the laboratory and the effects of
deliberate modifications assessed. For
example, the consequences to the
ocean circulation to be expected if the
planetary wind field were to be altered or the effects of barriers placed
across narrow gaps (such as the Bering, Florida, or Gibraltar Straits) can
be examined in rotating models. Similar studies can be made for the land,
such as the utter removal of all mountains from the earth or adding the
topography of past continental glaciers, but perhaps better in these cases
with numerical models. Both of these
investigative techniques have been
brought to useful levels of refinement
in the past two decades.
56
Granting a present capability to
make reasonable estimates of the
physical consequences of large scale
alterations of the land and sea, the
difficult part of the question of nonatmospheric intervention in climate
and weather is shifted to that of field
methods, power requirements and controls; and of the sites for possibly desirable surface alterations. In this
connection the ocean offers some
especially interesting possibilities.
It is now well established that the
ocean is characteristically in a state
of stable density stratification. While
density increases with depth; in the
tropics and subtropics the surface
water tends to be warm and salt while
the subsurface layers grow colder and
somewhat fresher with depth. The
transition zone between these two
principal water types is the main
thermocline which is found at a depth
of about one-hundred meters in the
tropics and some several hundred
meters in middle latitudes. Thus to
cool the surface of the ocean it is
necessary only to bring the cold water
below the main thermocline upward
through the relatively short distance
to the surface.
This might be done with some efficiency by infusing the cold layers
with a curtain of small bubbles. If the
entrained water is lifted isothermally
it will tend to sink again; but if the
process is quasi-diabatic a mixture of
cool, somewhat fresher water can be
made to remain on the surface and
to move off with the surface current.
The effect on the atmosphere of
such alterations of the surface temperature of even great torrents like
the Gulf Stream or Kuroshio might be
small at first because, though swift,
these currents are very narrow. Still,
in time, the wind-driven Ekman transport would carry the modified surface
layer seaward and generalize the influence of surface cooling.
In Arctic waters bubble sheets have
been proposed to keep navigable waters clear of ice. But in low and middle latitudes surface warming is more
difficult to contrive. For the North
Atlantic there is a possible procedure
in the fenestration of the Panamanian
Isthmus.
These influences depend on the
thermal stability of the oceans. But the
salt burden of the ocean is unstably
stratified. The warmth of the surface
water permits the uppermost layers
to be saltier than those at depth. In
consequence a parcel of warm, salt
surface water carried downward and
57
allowed to lose heat to its surroundings, will continue to lose buoyancy
and sink. Conversely, a parcel of cold,
relatively fresh deep water once
started upward, will continue to gain
buoyancy and rise. Such parcels cannot be large, because of the heat
transfer requirements, but there is
nothing, in theory, to prevent them
from being so numerous that their
net affect on vertical mixing might be
of geophysical significance.
Finally it may be worth recalling
that the surface of the ocean receives
more than two-thirds of the world's
supply of precipitation and dew, and
is the ultimate reservoir of not only
river discharges but glacial melt water.
All of this water is fresh but presently
irrecoverable. Still more fresh water
substance lies bound as ice. Ice is recoverable. Should the need grow so
desperate or economical means of
transportation be devised, ice and its
melt water provide an as yet unexploited resource.
CONCLUSIONS ANO
RECOMMENOATIONS
The Commission concludes that
sound progress toward the technology
of weather and climate modification
must be based on four fundamental
pursuits:
assessment and development
of an understanding of
natural climatic change.
assesment of the extent and
development of the understanding of inadvertent modifications of weather and climate.
improvement of the process
of weather prediction as a
social benefit and as proof of
scientific understanding of atmospheric behavior, and
development of means for
deliberate intervention in atmospheric processes for
weather and climate control
and evaluation of their consequences.
As steps toward these attainments the
Commission recommends that the following enterprises be fostered:
Examination of the routes, rates
and reservoirs of water substance and energy exchanges in
all aspects of the hydrologic
cycle.
Investigation by numerical laboratory and field experiments of
58
the dynamics of climate as a
basic study for weather modification technology.
Advancement of weather prediction as a proof of understanding, including support of
this effort by the establishment
of a global weather observation
network.
Broadening of the knowledge of
cloud physics and dynamics in
the laboratory and field, with attention to wave phenomena and
an evaluation of electrical influences.
Study of the effects of large
scale surface modification by
numerical and laboratory models
of the oceanic and atmospheric
general circulation, and of practical means for surface modification of the land and sea.
Study of the radiative effects of
changes in the atmospheric composition and alteration of its
transparency that urban growth
and new forms of industry,
transportation or land use may
evoke.
59
INTRODUCTION
Man is an organism directly dependent on other organisms for many
of his materials. He also struggles
with other organisms, most of them
quite small, that prey upon him, eat
his food, or otherwise challenge his
existence. Anything that has a general and significant effect upon plants
and animals, making some more abundant, others less so, is of primary concern to mankind, for it strikes at the
very basis of human existence.
Changes in weathr and climate may
be expected to have such effects. It
follows that any program of weather
modification must give serious attention to adverse as well as beneficial
biological aspects.
As Lynton CaldweIl observed in the
Yale Review, "Biopolitics: Science,
Ethics and Public Policy," Vol. LIV:
1-16, 1964, biologists are with increasing frequency finding themselves at
variance with other segments of society on matters of public policy. Examples range from questions concerning how much radioactive or pesticidal materials should be permitted
loose in the environment to the relative merits of trying to preserve from
extinction a natural species population. Contrary to J. P. Miller's whimsey biologists cannot limit themselves
to "proving that what must be done
for political reasons is biologically
safe for the human race."
MEANS Of PREOICTINO
CONSEQUENCES Of
WEATHER MODIFICATION
It must be recognized that the present state of knowledge places uncomfortable limits on the prediction of the
biological consequences of modifying
the weather. Several lines of investigation can be used, however, to provide information.
The Study Committee of the Ecological
Society of America was asked by the National Science Foundation to undertake a
study of the present status of knowledge of
effects of weather and climate on plants and
animals and to recommend the type of biological program that should be associated
with research in weather modification. The
study was made by an Ad Hoc Weather
Working Group, chaired by Daniel A. Livingstone, Duke University, and is reported
in a paper entitled "Biological Aspects of
Weather Modification," to be published in
the March, 1966 issue of the Bulletin of the
Ecological Society of America. See the Ap pendix.
RIOLOOICAL
ASPECIS OF
WEAVER
MODIRCATION
60
These will be discussed, indicating
the special advantages and deficiencies of each avenue of study.
Lalioralory SIUMOS
A single organism or a small number
of the same species can be subjected
to controlled experimental conditions
in the laboratory, and the response
to various elements of climate, such
as temperature, moisture and light,
systematically investigated. This
basically straightforward approach is
not without complications. If, for example, one seeks to investigate the
effect of temperature upon the growth
of a plant species, it is not sufficient
to measure the plant's growth at a
variety of constant temperatures.
Some plants are more influenced by
the daytime temperature, some by the
night temperature, while others thrive
best under conditions that are specified by the difference between day
and night temperature. The responses
to light are similarly complicated. For
reasons such as these, the experimental approach has been applied to a
very small fraction of the known species of plants and animals, and there
are only a handful, such as man, the
speckled trout, the loblolly pine, and
a number of crop plants, that have
been investigated at all exhaustively.
This laboratory approach has several deficiencies as a means for predicting the field results of weather
modification. The response to weather
may be very different for organisms of
the same species collected in different
parts of its range. Because of genetic
changes, an organism taken directly
from the field and grown under controlled environmental conditions in
the laboratory may react differently
from one which is the result of several generations of genetic selection
pressure in a large population growing
under similar conditions. The most
serious deficiency of this approach is
that it treats species in isolation. In
nature, very few organisms are limited in range by direct climatic conditions that exceed their physiological
limits, but rather by competition with
other species that are better able to
cope with the prevailing conditions.
Such considerations limit the applicability of results obtained in the laboratory for predicting results of
weather modification in the field.
61
ROCOP93 Of AnnUal Variation
The results of year-to-year variations in the natural weather on biological phenomena can be used as a
basis for predicting the results of similar perturbations produced by man.
This method is suitable for predicting
the effects of short-term weather modifications that are similar in nature
and extend to natural climatic fluctuations. With these limitations, it can
be used to predict the offsets of
weather modification upon a few
well-studied crop plants of great economic importance, and a few wellstudied insect or microscopic pests.
DloeograpklcaI and
Fainecapical ROCONS
Biogeography furnishes another useful source of information about the
relation of organisms to climatic factors. Correlations between the distribution of organisms and climatic
conditions suggest that climate has a
primary role in determining these distributions. The predictions that can
be made from biogeographical data
are safest when they are most general.
A change from grassland to savanna
under increased rainfall can be predicted much more securely than the
species composition of the savanna or
the exact amount of rainfall increase
that would be required to effect the
change.
Study of the fossil record has also
provided a wealth of information
about the biological effects of a particular set of climatic changes, those
ticular set of climatic changes, those
associated with glacial and interglacial conditions, and a substantial body
changes in the more remote proglacial
periods. Use of these data is hampered
by lack of independent information
about the actual physical changes in
climate that were involved, so that
much investigation of these changes
consists of an attempt to infer climatic changes from the biological evidence, rather than determining the
way in which organisms have been influenced by climate. Nevertheless, the
fossil record gives the only available
information about the biological resuits of a major climatic change on a
global scale, and for this reason it is
particularly valuable.
62
monnorine 01 Selectefi
Communities
Experimental plans for weather
modification should insure a maximum yield of biological data on the
nature of effects. This requires both
the establishment of comparable control areas outside the areas of modification and pre-modification monitoring of sample areas in both the
control and modified areas. Natural
communities would be selected for
study in an area in which weather is
to be modified and permanent experimental plots established in them. Well
before weather modification, the biota
on these plots should be inventoried
in detail and mapped or photographed.
Such studies should precede modification by a long enough period to collect data on the normal fluctuations of
the communities and populations. The
plots would be re-studied during and
after periods of weather modification
to determine what species expanded
their populations and what species
lost ground; what species disappeared
from the community and what new
species entered. Since proper evaluations will require confidence limits for
any statements concerning effects, the
sample areas must be well replicated.
Monitoring experiments will be difficult to set up. It is patently impossible
to study every species in a rigorous
way, and it is quite possible that randomly selected species will turn out
not to be those most useful for the
study. Some guiding principles might
include a mixture of the following
attacks: 1. A well-replicated series of
reasonably detailed examinations of
selected natural biological arrays at
transition areas joining biological
communities which are apt to show
changes with the predicted shifts. 2.
Examination of a range of agricultural
and other artificial ecosystems for
changes in disease, pests, yields, harvest dates, etc. 3. Studies of relative
changes in population sizes, reproductive success, etc., of a selection of
more easily studied organisms within
blocks of homogeneous natural communities away from transition areas.
Reasonable controls are essential;
hence, in order to be effective, monitoring must be done outside these
areas in comparable sites.
63
COMPHIP SIMU18900 SIUMBS
Computer simulation studies provide a method for predicting biological effects of weather modification.
Two quite different approaches to
computer studies are available. A
model that approximates reality very
closely cannot be made at present for
any given area because of the lack of
data. Hence, computer experimentation may need to be postponed for 5
to 10 years until the requisite data on
the location in question are available.
An alternative is to proceed immediately to construction of a simulation
model, using data on the same, or related organisms from places other
than the proposed site for the weather
modification experiment. In so doing
the following question must be asked:
"How would an ecosystem similar to
that which presently exists at the site
for the weather modification experiment be altered if one modified typical sequences of weather data within
ranges of values known to be realistic?" In general, the type of thing to
determine with simulation studies is
whether certain combinations of strategies or strategies used singly, show
certain broad features that are relatively invariant even when independent variables are run through a wide
range of values on the computer. Also,
it is desirable to see if certain strategies are grossly uneconomical if applied under certain circumstances.
The logic of the simulation approach is bolstered by studies on such
insect pests as the spruce bud worm.
Through the longterm concerted effort of large teams of investigators, it
has been possible to construct models
sufficiently close to reality to have
practical use in predicting outbreaks
and in choosing control strategies.
Outbreaks of plant diseases are probably also capable of being studied
with the same methods.
The principal motivation for computer simulation is cost. It is enormously cheaper to run experiments
on the computer than to try out a
great variety of weather modification
experiments in nature and observe the
results. Both the cost of the experiment and the losses due to the experiment by using simulation as a supplement to an actual experimental program are saved. The basic structure of
the computer simulation program will
be a set of functional relationships
which mimic the dynamic properties
of all relationships between and within
[]
soils, plants, animals, site factors and
weather, with respect to changes both
in variables through time and in dispersal of entities through space with
the passage of time.
PREDICTED BIOLOGICAL RESPONSES
OF WEATHER MODIFICATION
An ecological system consisting of
agricultural fields is well enough understood that effects of specified
weather and climate modifications
can be predicted with some assurance.
In a more complex system consisting
of many more species of interacting
plants and animals, the complexity is
so great that it is not possible to make
detailed quantitative predictions.
However, certain general effects can
be outlined. In illustrating this, consider temperature changes up to several degrees Fahrenheit and rainfall
changes, principally increases, of
some tens of percent of the present
annual average on reasonably wellwatered lands.
eenemi Enecis
Paleoecological studies in many of
the climatic regions of the earth indicate that temperature modification
corresponding to an annual average
difference of 3 ° to 4°F. brings noticeable alterations in population levels of
many resident plants and animals and
the appearance and disappearance of
some other species. In many cases,
however, the broad kind of vegetation, such as hardwood forest or
grassland, still remains. A change in
temperature of twice this magnitude
brings replacement of many species
by others, wide changes in population
levels of species present at both extremes, and in many cases replacement of one major kind of community
by another.
From long-term studies of the
American prairie, it may be predicted
that the direct effect of moderate
changes in rainfall on the biological
communities as a whole may be expected to be relatively slight, mostly
involving shifts in sites occupied by
species. The changes will probably be
slow unless large areas become defoliated or killed through the anticipated
increase in certain pests or the corn65
munity is otherwise seriously disturbed. However, changes in rainfall
or temperature which are of sufficient
magnitude to have general usefulness
seem likely to be of sufficent magnitude to produce substantial disturbances in natural communities.
Most studies showing correlations
between weather conditions and
changes in the abundance of one or
more species of organisms have also
brought out the fact that it is the
weather during a few critical months
that is important, rather than the average conditions over the years. Thus,
for many species, a minor increase in
the average annual precipitation could
mean either enormous increases or
great mortality, provided that the
extra rain fell during a period that was
critical for survival or reproductive
success.
increase in CPOP PrOdUCHYR
It seems quite clear that an increase
in rainfall would result in an increase
in production of cultivated crops over
a large part of the earth. Even a reduction in variance in rainfall, or the
ability to control its seasonal distribution, would lead to an increase in
productivity if all other conditions
remained the same, because the increased reliability of the return would
permit more efficient farming operations.
species Extinction and Disruption
01 Nampai communines
With the growth of human population and its spread over the land in
the United States, native species are
increasingly confined to small sanctuaries—parks, wildlife refuges, and
mountain ranges. These are islands
surrounded by oceans of land intensively occupied by man, and it is not
generally possible for wild species to
migrate across the rural and suburban
oceans from one island to another, to
survive climatic change. If climate is
so changed that a species is no longer
able to survive in a given natural area,
that species cannot migrate but must
become extinct there. Extinction of
species implies reduction in speciesdiversity, the richness of natural communities in numbers of species. Reduced species-diversity and shifts in
population distributions resulting
from weather and climate modifica66
tion would combine to reduce the stability of natural communities.
There are differences of opinion
among biologists about the extent to
which a particular modification would
affect the stability of natural communities. Most would expect an appreciable disturbance to result from a
modification great enough to be useful
economically. Some species would become more vulnerable to outbreaks
of pests and some natural preserves
would become less aesthetically attractive and less valuable for research
purposes. The economic consequences
would be felt in communities that are
used for grazing or lumbering.
It is likely that the changes produced by weather and climate modification in insular remnants of natural
communities will be consistently unfavorable ones. Immigration of the
normal respondent species is subject
to interference. In more continuous
areas the shifts would result in more
temporary but not necessarily inconsequential instability.
ProaHIe Increase In crop Pests
For insect pests, there exist numerous studies indicating relationships
between abundance and weather conditions. The number of cases is sufficiently impressive to permit the conclusion that changes in weather from
year to year do lead to changes in the
abundance of certain species, and in
some instances lead to changes in
their distributions. It seems probable
that many, if not all, of these species
will be highly destructive to agricultural enterprises or to the natural
vegetation, or to both. Unfortunately,
too little is known of the mechanisms
of population control of most species
for us to be able to predict which
species will become serious pests
under altered weather conditions. It is
also true that some likely changes in
weather would result in abnormally
low populations of other species. Well
known examples of species for which
high rainfall is deleterious are the
chinch bug, Blissus leucoptorus, and
the pale western cutworm, Porosogrotis orthogonia. It is likely, however,
that weather modification will lead to
large agricultural losses due to the
increases induced in populations of
some terrestrial pest species, and that
these losses will not be compensated
by perhaps equally frequent reductions in the populations of other
species.
67
Pmhahie increase
in Disease VOCIOPS
One class of organisms, the ones
that are borne by arthropod vectors
and cause serious diseases in man and
his domestic animals, are deserving of
special attention. Although there is
some reason to believe that other diseases may be influenced by weather
conditions as well, it is clearly established that many of those with arthropod intermediate hosts are dependent
upon weather conditions. One can predict that weather modification would
produce a shift in the pattern of vector-borne diseases. In any plan to
modify the weather, disease must be
given very serious consideration, for
it may be of greater economic importance than the circumstances which
stimulated interest in weather modification.
The outbreak of many insect pests
seems to be triggered by a rather unusual meteorological situation in one
restricted part of the range. The population builds up first in that local center and spreads out in all directions in
the form of a wave. This pattern is
similar to that of many human diseases, some of them carried by arthropod vectors, such as bubonic plague.
It is not believed that an epidemic of
plague would necessarily result from
weather modifications, but the possibility exists that there might be some
sort of weather modification which
would cause it to occur. There is a
substantial reservoir of sylvatic plague
in the United States.
Many bacterial and fungal diseases
of crops are also known to be highly
responsive to weather. Increased rainfall, more summer humidity, warmer
or cooler temperatures would all have
effects on plant pathogens. Not enough
is known to predict the significance
of the almost certain changes.
Effect 01 Possible Rain-Sbagows
While an increase in precipitation
has predictable results among which
both favorable and unfavorable effects
can be expected, and which might off
set each other to some extent, a concomitant decrease in precipitation in
another area has no beneficial effects
to offset the obvious damage.
68
CONCLUSIONS AND
RECOMMENDATIONS OF THE
ECOLOOICAL SOCIETY
WORKING 6ROUP
Living things are adapted to the
weather that actually prevails, and
any change in that weather will be
generally deleterious to them.
The largest credit item for
weather modification is likely to be an
increase in primary production of the
drier parts of the land surface through
improvements in rainfall. Even the
ability to control seasonal distribution
of rainfall would lead to more efficient
farming operations. Realization of the
potential increase in production would
depend upon being able to modify the
rainfall without major pest outbreaks
and extinction and disruption of natural communities. It is not certain that
this would be possible.
The largest weather modification
debit item is likely to spring from the
decreased stability of communities,
which would manifest itself in an increase in pests, weeds, and pathogens.
The identity of the species involved
in these disruptions cannot be predicted, nor can their cost.
For the present, weather and
climate modification should be restricted to local small-scale operations.
Larger scale operations, such as
an attempt to increase the rainfall of
any substantial part of this country,
should not be undertaken, from a biological point of view, in the present
state of knowledge.
All weather modification experiments of a scale large enough to have
important biological consequences,
such as those currently envisioned for
the Upper Colorado Basin, should be
preceded and accompanied by careful
ecological monitoring and computer
simulation studies. Manipulating the
weather to obtain a net benefit will
demand much better understanding of
the interactions of weather, climate
and organisms than now available.
Adequate understanding of the
interrelationship of weather, climate
and ecology will demand a very expensive long-term research program.
Present resources of ecologically
trained investigators are inadequate
to cope with these problems.
The Working Group of the Ecological Society of America, which pro69
vided background material for the
Commission, was concerned primarily
with modifications of weather systems ranging from a single cloud to
an extratropical cyclonic storm. The
Working Group stated that short-term
modifications of weather of a magnitude similar to the fluctuations in
nature are least likely to have dangerous unforeseen consequences. If undesirable results appear, the modifications can be discontinued. Repeated
operations on the scale mentioned are
likely, however, to have far reaching
biological consequences as pointed
out in the previous sections, and some
of the biological changes would not
be reversible. This advisory group
recommended that repeated and long
term modifications of weather not be
attempted without prior careful and
well planned monitoring or computer
simulation studies of the biological
consequences of particular kinds of
weather modification.
70
STATISTICAL
ASPECTS
OF
WEATHER
MODIFICATION
THE PRESENT SITUTION
Problems of statistical methodology
arise when there is a controversy as
to interpretation of data already accumulated or as to ways of going
about acquiring additional information. That such controversy should
arise in connection with weather
modification experiments is hardly
surprising.
Almost twenty years after the original experiments in cloud seeding,
conclusive evidence acceptable to the
scientific community as to ground
precipitation effects of cloud seeding
is still lacking. The basic issue of the
effectiveness of seeding non-orographic cumulus clouds has been subject to sharp changes of opinion and
to conflicting evaluation in recent
months. In the absence of conclusive
guidance from scientific experimental
data, the National Academy of Sciences Panel on Weather and Climate
Modification embarked on an intensive statistical study of data from
commercial projects. This analysis
concluded with the impressively positive findings on the efficacy of cloud
seeding—a position supported in general by the available scientific data.
This analysis, however, has not completely dispelled the skepticism concerning evidence obtained as a byproduct of operational activities. The
question is not whether to use statistical but how to use it in the early
design and subsequent analysis of
experiments.
THE CONFERENCES ON
STATISTICAL METHOOOLOBY
The National Science Foundation
sponsored three conferences for the
This chapter draws upon materials assembled by Prof. Byron W. Brown, Jr. of
the University of Minnesota as a result of
three conferences held under the auspices
of a National Science Foundation grant.
These conferences brought together scientists actively engaged in weather modification research and statisticians experienced
in the planning of scientific experiments.
Also, acknowledgement is made to unpublished memoranda and letters by Dr. Julien
Bigelow (Institute for Advanced Study), Professor William Kruskal (The University of
Chicago), Dr. Theodore Harris (Rand Corporation), Professor Jerzy Neyman and Dr.
Elizabeth Scott (University of California,
Berkeley), Mr. Glenn Brier and Dr. Joanne
Simpson (USWB) and many other statisticians and scientists who participated in
these conferences. The list of participants in
these conferences appears as Footnote 1 to
this chapter.
71
purpose of bringing together statisticians and scientists interested in the
statistical aspects of weather modification experiments. The first conference, in January, 1965, brought together scientists participating in many
field experiments throughout the
country. These scientists briefly reviewed these programs and plans,
with special reference to the statistical problems that have been encountered. The statisticians present had an
opportunity to comment on these brief
reviews and on their own experiences
in this area.
The second conference, in April,
1965, focused on Project Stormfury.
The project director and the statistical
consultants for this project presented
the results of past work, the criticism
of this work, and the plans for the
summer of 1965. The statisticians and
weather modification scientists used
this project as the point of departure
for discussion of general questions of
design and evaluation of experiments.
At the third conference, in June,
1965, scientists in the Bureau of Reclamation, and in projects sponsored
by the Bureau, reported on a number
of Bureau projects and related work.
Again there was an opportunity for
other scientists and statisticians attending the meeting to ask questions,
comment on the presentations, and be
questioned in turn.
CONFERENCE FINOINOS
A number of results have come
from these conferences.
Field experiments are a necessary part of a research program on
weather modification by cloud seeding. Laboratory experiments of the
scope and refinement necessary to
predict field results are not economically feasible and, further, the theory
necessary for laboratory simulation of
the mechanisms of free air precipitation has not been developed. Practical
effects must be estimated in the field.
The number of variables involved and the lack of knowledge
about the details of atmospheric processes make weather modification
field experiments difficult to plan and
evaluate. Careful use of the best techniques in scientific methodology is required. This entails the cooperation of
scientists who can frame the hypotheses and specify some of the important variables, statisticians who can
suggest ways of using this information
to gain precision, mathematicians, in72
strumentation specialists, engineers,
hydrologists and others.
Many of the investigators in this
field do not have formal training in
statistical methodology. A few do not
realize this methodology is essential
to their work. Others realize the usefulness of statistical methodology for
planning and evaluation, but do not
have adequate statistical support for
their programs.
Planing and evaluation of weather modification experiments present
some special problems in statistical
methodology. These problems must
be resolved or circumvented if research in weather modification is to
benefit from the use of statistical
principles. Statistical research is
needed in questions such as the following: optimal spacing of rain gages,
optimal use of rain gage data, effects
of crystals contaminating unseeded
areas, best ways of taking advantage
of auto-correlations and cross-correlations in rain gage data.
CONFERENCE RECOMMENDATIONS
1. Statistical training should be
given greater emphasis in the academic program of scientists and engineers interested in the atmospheric
sciences. This statistical training
should include the principles of field
experimentation—nature of statistical
models, random allocation of treatments, local control, replication and
blind evaluation—as well as the classical techniques of design and data
analysis.
Steps should be taken to assure
that government-supported research
utilizes statistical principles in planning and analysis. It is desirable that
statisticians participate with meteorologists, and other scientists, in the
evaluation of proposals for government-supported research.
Statistical advice for scientists
in this field should be made available
through (i) sponsorship of conferences
(e.g., the Foundation series) where
plans for new projects can be presented for criticism; (ii) use of statisticians as members of the committees
evaluating government-sponsored research; (iii) establishment of task
forces and advisory panels for large
projects; and (iv) inclusion of one or
more statisticians in each field experiment team.
Research in statistical methodology applicable to weather modification programs should be promoted
73
and supported. Such research should
include: the development and validation of statistical models; development of useful formulations of
meteorological hypotheses; and investigations of the statistical characteristics of the measuring instruments used
in this field.
It is strongly recommended that
any regulatory agency include as one
of its technical members or advisors a
person knowledgeable in statistical
principles and techniques.
Steps should be taken to work
out a voluntary system that assures
that commercial seeding operations
do not contaminate or vitiate scientific field work carried on in specified
areas of the country. Furthermore,
efforts of commercial seeders to
gather valid evidence on the magnitude of seeding effects should be encouraged but should not be required
of commercial cloud seeding operations.
PRECIPITATION-ORIENTED
EXPERIMENTS
A basic source of controversy and
uncertainty in the field of weather
modification by cloud seeding has
been the relative scarcity of "precipitation-oriented" experiments. An experiment is "precipitation-oriented"
if it provides adequate information
about ground precipitation in the area
presumably affected by cloud seeding
as well as in control areas. The doubts
concerning conclusions from commercial cloud seeding operations were
expressed forcefully after the publication of the report of the Advisory
Committee on Weather Control. These
doubts arise from the possibility that
various forms of selection bias exist,
as well as biases due to non-linear
transformations performed on the precipitation data. Still, no specific source
of bias has been discovered that
would account for all of the positive
findings contained in the recent NAS
Panel analyses.
In a field such as weather and climate modification, the statistical
methodology of bias elimination becomes particularly prominent. Randomization is then naturally in the
foreground.
Modern statistical design and evaluation are based on a probabilistic
model intended to present the important aspects of the phenomenon being
studied. The tools of modern proba74
bility theory are extremely flexible so
that the underlying probabilistic
model may be far removed from the
oversimplified concepts of "randomness" in the sense of serial independence, constancy of probability distribution over time, or rectangularity of
the probability density function.
But since experimental resources
typically limit the obtainable sample
size or the period of observation, it
is important not to neglect the power
of test procedures and other dimensions of statistical efficiency. A multidimensional or profile approach,
based at least in part on the physical
theory of the observed phenomena,
will be particularly effective.
Among the ultimate aims of a
planned "precipitation-oriented" experiment must be a contribution to
the understanding of the mechanism
by which cloud seeding succeeds or
fails in influencing ground precipitation. Therefore, the fact that precipitation on the ground is to be carefully
measured does not exclude the collection of observations of other physical
variables.
THE EMPIRICAL APPROACH
It has been claimed that answers to
the weather modification problem can
only come from basic research. This
argument suffers from two defects:
There are numerous precedents
where the effectiveness of human
action has been empirically established beyond reasonable doubt many
years before any degree of understanding of the underlying mechanism
was attained. Thus, there is no basis
for claiming that the understanding of
the underlying atmospheric mechanisms is a necessary condition for a
determination of effectiveness of
cloud seeding in generating ground
precipitation.
Even a complete understanding
of the causal relations in cloud seeding might fail to answer the question
of the effectiveness of cloud seeding.
To answer the latter question on the
basis of the theory of the underlying
mechanism, one would still need comprehensive information concerning
the distribution of the initial values
of the various atmospheric parameters.
This information is not at present
75
available and might be extremely duff icult to come by.
The basic recommendation is that
a program of planned field experiments be undertaken, possessing continuity over a period of 5 to 10 years
and on a scale sufficient to permit
geographic comparisons and differentiation, as well as stratification according to the type of seeding agent,
mode of injection, cloud type, etc.
Provision should be made for the inclusion of relevant precipitation data,
in addition to other relevant physical
variables. This program should be
undertaken, designed, and evaluated
in close association with statisticians
with extensive experience in experimental design.
In view of the emphasis on the
physical aspects of weather modification experiments, it is important to
remember that such experiments provide a unique opportunity for monitoring variables in the realm of
biology, ecology, and social phenomena related to weather modification.
Indeed, the design of weather and climate modification experiments should
incorporate the needs of these fields.
Ecologists will provide suggestions as
to design, making it possible to observe the effects on various species;
the social psychologists will provide
for observations on human perception
of weather modification activities, and
the economist will concern himself
with productivity effects, etc. The
details of this aspect of experimentation must be worked out by experts
in the respective substantive fields,
but their conclusions will have to be
carefully considered by the statisticians in guiding the experimental design.
NUMERICAL MODELINO
AND SIMULATION
The techniques of numerical modeling and simulation complement and
expand the potential of statistical
analysis. In fact, they are high-powered substitutes for paper and pencil
calculation of the behavior of complex
systems under assumed conditions,
parameter values, etc. Plausible values
to be assumed must still be generated
by empirical research in which statistics is likely to play an important role.
Modeling and simulation require the
existence of a mathematical theory of
the phenomenon, making it possible
to establish a link between such van76
ables as cloud seeding and precipitation.
When the mathematical model has
not yet been developed or when
realistic information on the relevant
parameter values is not available,
numerical modeling may not be feasible or fruitful. In such circumstances
it may still be possible to arrive at the
empirical relationship between seeding and precipitation by intensive
systematic randomized and stratified
field experimentation or by nonexperimental statistical analysis.
On the other hand there are situations, as with large scale circulation
problems, where field experiments are
impossible, while a mathematical
model is available from dynamic
meteorology and there is information
on parameter values. Here numerical
modeling can and should be used.
In some cases mathematical model
and parameter information exist, but
in an incomplete form, while field experiments are possible though difficult. Here a combination of direct
statistical analysis together with numerical modeling and simulation may
be employed to advantage.
COMMISSION RECOMMENDATIONS
The Commission recommends:
Statistical training for meteorologists should be promoted in academic
programs. Intellectual interchange between scientists and statisticians
should be continued through periodic
seminars.
Statistical consultants should be
made available to scientists in this
field through the support of conferences where new projects can be presented, through use of statisticians as
evaluators of proposed work, and
through the support of task forces and
advisory panels, with statistician
members, for large projects. Statisticians should aid in the evaluation of
proposals for government-supported
research.
Steps should be taken to assure
that plans for government-supported
research utilize statistical principles
in determination of design and size.
Research in methodology should
be promoted. This includes the development and validation of statistical models, uniformity trials and other
investigations of the statistical char77
acteristics of the instrumentation in
this work.
It is urged that any regulatory
agency that might come into being
should have a staff statistician to
guide efforts to gather valid evidence
on the magnitude and effects of cloud
seeding.
A program of carefully planned
precipitation-oriented field experiments should be carried out under
complete control of the scientists,
embodying the required technical
knowledge, possessing continuity over
a period needed for conclusiveness,
and on sufficient scale to permit geographic conclusions, as well as statistical stratification according to the
type of seeding agent, mode of injection, cloud type, etc.
78
NOTNOTE
1 List of Participants in Conferences
Baughman, Robert C., Forest Fire Laboratory, U. S. Forest Service, Missoula, Montana
Bearman, Jacob E., School of Public Health,
Biostatistics Division, University of Minnesota, Minneapolis
Bigelow, Julien, Institute for Advanced
Study, Princeton
Bollay, Eugene, P. 0. Box 1022, Boulder,
Colorado
Braham, Roscoe, Department of Geophysical Sciences, University of Chicago
Brier, Glenn W., U. S. Weather Bureau,
Washington, D. C.
Brown, Jr., Byron Wm., School of Public
Health, Biostatistics Division, University
of Minnesota, Minneapolis
Court, Arnold, Department of Geography,
San Fernando Valley State College, Northridge, California
Dennis, Arnett, Institute of Atmospheric
Sciences, South Dakota School of Mines
and Technology, Rapid City, South Dakota
Grant, Lewis 0., Atmospheric Science Department, Colorado State University, Fort
Collins, Colorado
Hindman, Ed, Department of Atmospheric
Science, Colorado State University, Fort
Collins, Colorado
Hosler, C. L., Department of Meteorology,
Pennsylvania State University, University
Park, Pennsylvania
Hoyle, Michael, Cloud Physics Laboratory,
University of Chicago, Chicago, Illinois
Hurwicz, Leonid, Department of Economics,
University of Minnesota, Minneapolis
James, R. C., Bureau of Reclamation, Denver
Federal Center, Building 53, Denver, Colorado
Kahan, Archie M., Office of Atmospheric
Water Resources, Office of Chief Engineer, Bureau of Reclamation, Denver Federal Center, Building 53, Denver, Colorado
Kruskal, William, Department of Statistics,
University of Chicago
Malone, Thomas F., Research Department,
The Travelers Insurance Company, 1
Tower Square, Hartford, Connecticut
Markovic, Kadmilo D., Civil Engineering
Department, Colorado State University,
Fort Collins, Colorado
Mielke, Paul, Mathematics and Statistics Department, Colorado State University, Fort
Collins, Colorado
Peahl, Laurence E., Department of Mathematics, Taft Junior College, Taft, California
Reinhardt, Howard, Montana State University, Missoula, Montana
Schleusener, Richard A., Institute of Atmospheric Sciences, South Dakota School of
Mines and Technology, Rapid City, South
Dakota
Simpson, J. M., U. S. Weather Bureau, Washington, D. C.
Snyder, Marshall, Department of Statistics,
University of Chicago
Tick, Leo J., Data Processing and Computing
Laboratory, Research Division School of
Engineering, New York University, University Heights, New York, New York
Van Ness, John, Department of Statistics,
Stanford University, Palo Alto, California
Willis, Paul, E. Bollay Associates, P. 0. Box
N, Steamboat Springs, Colorado
Wyckoff, P. H., Atmospheric Sciences Section, National Science Foundation, Washington, D. C.
Yevdjevich, Vunica M., Foothills Research
Campus, Colorado State University, Fort
Collins, Colorado
Youden, W. J., Applied Math Division, National Bureau of Standards, Washington,
D. C.
Zopf, D., Eugene Bollay Associates, P. 0.
Box N, Steamboat Springs, Colorado
79
Like other recent technological advances, weather and climate modification techniques, if fully effective,
present humanity with unprecedented
opportunities and grave dangers. So
pervasive are the elements of weather
in the mind and works of man that an
alteration in one of them, even over
a small area, may provoke intricate
social changes. Some of these changes
are obvious but many are difficult to
trace and puzzling to measure.
A modification in a small area of
atmospheric circulation may cause
shifts in the system of human production and communication, as when fog
dispersal makes possible an airplane
flight that otherwise would be
grounded. It also may lead to unwanted conditions; thus, the measures
to dissipate fog may increase the icing
of highways in the immediate airport
area. Modification at one place may
provoke changes in the atmospheric
circulation elsewhere, as when there
possibly forms a "rain shadow" of
decreased rainfall to the detriment of
a wheat farmer in the lee of an indUced increase which brings profit to
another farmer, or when the weather
that pleases the wheat rancher causes
distress to the nearby cherry orchardist.
The effects of the modification on
man's activities sometimes are direct,
as in the case of fog dissipation, but
more often they operate indirectly
through alterations in the hydrologic
system or in biological ecosystems.
Their extent is especially troublesome
to discover because a sustained program of modification would change
the climatic characteristics, and the
whole fabric of society, being subtly
adjusted to climatic means and extremes, is likely to change with them.
The gains and losses that follow in
the train of atmospheric alterations
accrue to other processes of society
as well as to economic production and
consumption. The organization of
livelihood may be affected, and the
* The Commission had the benefit of
thinking contributed by participants in a
Symposium on Economic and Social Aspects of Weather Modification held at
Boulder, Colorado on July 1-3, 1965 by the
Department of Geography of the University
of Chicago in collaboration with the National Center for Atmospheric Research
under a grant from the National Science
Foundation. Papers from that symposium
shortly will be published in the University
of Chicago Geography Research Papers
under the title of Human Dimensions of
Weather Modification, edited by W. R. Derrick Sewell. The list of participants in the
Symposium appears under Footnote I to
this chapter. Also see the Appendix.
THE HUMAN
EFFECTS OF
WEATHER
AND CLIMATE
MODIFICATION
so
quality and enjoyment of life may be
enhanced or degraded.
Just how significant these chains of
events may be on human activity still
is largely conjectural. A few, such as
the increase of hydroelectric generation from induced precipitation in the
drainage above a power plant may be
gauged with some confidence. According to some estimates, even highly
modest precipitation increases at the
right times in cultivated areas are
likely to be of major value. The direct
benefits to agriculture and forestry
from hail prevention and lightning
suppression are likely to be significant
and not too difficult to estimate. Many
effects cannot be measured readily. To
the uncertainty of what modification
is within man's grasp therefore must
be added his ignorance of the full
consequences of whatever modification he may achieve. In the face of
uncertainty as to modification techniques and of doubt as to their social
effect, a sound public policy encourages research on both techniques and
effects so as to fully exploit what may
be an historic opportunity while
guarding against heavy or irreversible
damages to society.
After outlining several basic social
problems attaching to weather modification, there are recommended measures which should be taken by the
Federal Government to deal with immediate questions of research and
field operations and to improve the
nation's capacity to deal with larger
questions that loom in the future.
In canvassing these issues the Commission has drawn on the experience
and outlook of scientists who have
worked with modification of other
aspects of natural resources. There
has been only a little study of weather
and climate impacts alone, but the effects of managing water and land
yield many relevant lessons.
The final report of the Advisory
Committee on Weather Control contained an appendix relating to economic evaluation. However, it did not
instigate any concerted effort to improve capacity to measure the human
effects of weather and climate modification. A few thoughtful studies were
made but the problem was neglected
for the most part. In making it possible for workers from anthropology,
economics, geography, meteorology,
political science and related fields to
assess the current state of their
knowledge, the Commission sought to
identify points where predictions now
81
are practicable and questions deserv ing more intensive study.'
FOUR INTERLOCKING SYSTEMS
It is important to recognize that although man may seek to modify
weather in order to benefit the quality
of his life the result is rarely a simple
relation between an atmospheric condition and human activity in that
place. Atmospheric circulation, the
hydrologic cycle, biological ecosystems, and human production are interlocked. There may be a direct and
largely limited connection between atmosphere and economic production,
as with fog dissipation or lightning
suppression. More often, the benefits
and costs to the system of production
and communication are felt indirectly
through changes in the hydrologic cy
cle and in biological ecosystems: a
shift in the atmosphere changes one
or more of the other three. Thus, an
increased amount of June rainfall in
the High Plains of Colorado would
affect the production of wheat by adding to soil moisture and the capacity
of plants for transpiration and of soils
for evaporation. Stream flow and
ground water supply in the area therefore would be altered in some degree,
however slight. Enlarged wheat harvest would be the major outcome but
by no means the only one.
As has been shown in the preceding
chapter, the resulting shifts in ecosystems of plants, animals, soil, and
microclimate are exceedingly difficult
to assess. If they cannot be identified
fully their long-term significance for
human activity cannot be gauged.
Much the same problem is associated with sectors of the hydrologic
cycle. Certain changes in stream flow
which would result from increasing
precipitation or from decreasing evapotranspiration may be estimated. It
increasingly is possible to predict the
modification in stream flow resulting
from changes in precipitation and temperature. After a soil is saturated a
small increase in rainfall may cause
a proportionately larger increase in
runoff. There is less knowledge about
the likely effects of such changes on
the movement of silt downstream, or
about the relation of rainfall intensity
to rates of gully cutting in and regions
such as the Upper Rio Grande basin.
Lack of full understanding of the
consequences has never been a reason
for man to forbear modifying a part
of his environment. He does not re82
frain from ploughing a Carolina field
because he is ignorant of the full effects upon soil biota or upon runoff.
He has not held up the construction
of storage dams in Kansas because of
doubt as to the readjustments in channel cross section and gradient which
will take place downstream when the
flow is regularized. Moreover, in seeking to alter the landscape in one way
he may unwittingly cause damages to
others. There never is a time in the
present state of scientific knowledge
about air, soil, water, plants, and animals when these changes can be recognized in all their complexity. To
defer action until all the consequences
are tallied up would be to halt all new
resource management. Yet, there have
been times when the public decision
to go ahead in ignorance has led to
bitter regrets, as when highly erosive
soils have been ploughed and new cycles of gully cutting have been triggered; or as when channel works have
caused heavy silting and dislocation
of downstream drainage systems.
In considering the possibility of a
new tool of environmental modification which may be coming into man's
hands, the challenge is to find a course
of action which without inhibiting
largely beneficial results will curb
those measures which might bring
serious or irreversible damages to the
environment. Arriving at such judgments requires not only recognition of
what is known and not known about
the atmospheric, hydrologic, and biological systems affected, but assessment of how a change in one or all of
them will affect human life and of
how one kind of change compares
with another.
Weather and climate modification is
distinct from the more conventional
tools of environmental change in several respects. It promises to ordinarily
affect areas distant from those where
modification is tried: more than any
other readily available tool it may extend its effects across the frontiers of
countries, states, and nations. Its potentials for provoking local and international conflict therefore are great.
It usually has consequences for both
hydrologic and biological systems. It
is new. For these reasons there is
greater likelihood that man at the outset will see the gravity as well as the
exciting opportunity of modification
measures and that conscious attempts
will be made to weigh their future
consequences for society at the local,
national, and international levels.
However, the techniques so far devel83
oped are cheap, readily moved from
place to place, low in capital investment, and often free from the hazard
of irreversible shifts in the atmosphere. These reasons tend to stimulate
small-size operations widely dispersed
in time and place, and to offset the
caution that otherwise might apply.
UNCERTAINTY
Uncertainty characterizes most
thinking about the changes in natural
systems that are subject to modification. Not only is there uncertainty
about how much the atmospheric circulation can be altered and what this
would mean for the movement and
quality of water, plants, and animals,
but the consquences for human production and communication are subject to similar doubt.
This is one of the factors accounting for the casual attention which has
been given to the social consequences
of weather and climate modification
since publication of the report of the
Advisory Committee on Weather Control in 1957. An appended paper
pointed out the need for more systematic examination of the human ef
fects of modification. Little was done
thereafter. Doubt as to the possibility
of changing the weather led scientists
to ignore the challenge, and they were
supported in this by the silence of
the Advisory Committee on Weather
Control as to the need, by the scepticism of many atmospheric scientists,
by the debate in the academic community over the statistical methods
used in judging cloud-seeding experiments, and by the caution of Federal
agencies in encouraging new research.
There was no agency specifically
charged to look into the human ef
fects, and within the National Science
Foundation the responsibility for
weather modification research was
lodged in the Section on Atmospheric
Sciences.
The principal lesson to be drawn
from this experience is that where uncertainty is large, as it continues to be
with weather and climate modification, the basic social implications will
tend to remain unexplored unless explicit and sustained effort is made to
stir up and support the essential research. Otherwise, the human problems are ignored until they burst into
prominence on the heels of an improvement in technique.
Where uncertainty is high there is
much in favor of a public strategy
which promotes diversification of efforts rather than dependence upon
one line of action or research. Not
only would this call for pursuit of
studies on a variety of physical processes, but it would suggest that the
needs for and damages from theoretically possible modification would be
examined in advance of perfection of
techniques. In promoting a strategy
of diversification it is important, however, to avoid spreading the research
so thinly that no one project is rewarding. Allocation of funds among
different aspects of modification presumes a rough judgment of what kinds
of changes would be desirable in improving the quality of human life.
TWO APPROACHES TO THE
HUMAN DIMENSIONS
Investigation of the human dimensions of weather modification can
move along either one of two lines.
A possible modification, such as precipitation induction or lightning suppression, can be assumed and then an
effort made to estimate what the consequences would be in the society.
Where a modification is tried, as in
seeding above a hydroelectric plant,
the effects upon power production
downstream and in the generating
network may be traced. A variant is
to assess the effect of rare meteorological events. A second approach is to
ask at what points the social system
would be sensitive to a change in
weather conditions, and from this to
estimate what would be the more desirable and undesirable changes which
might be foreseen without regard to
whether or not they currently are
practicable.
Under the first approach, the attention is directed toward discerning the
likely impacts of modification which
promise early achievement. Under the
second, the emphasis is on types of
modification which should be sought
or avoided. The two approaches are
not mutually exclusive, and they can
helpfully supplement each other. Both
are recommended for early action.
BROADER CONSIDERATIONS
Whether emphasis is upon forecasting effects of practicable modification measures or upon points in society which would be more sensitive
to weather changes, there is doubt
85
as to how far man properly should go
in tampering with atmospheric systems unless he is relatively clear as to
the major consequences. Concern
with growing world population needs
heightens the interest in gains from
the weather. Doubt as to human implications as illustrated by the difficulty of assessing results of nuclear
experiments, has raised new cautions
concerning any novel or large-scale
interference with our environment.
Great prudence is therefore warranted
in practicing weather modification,
and increased support is desirable to
explore its side effects, as well as its
ability to achieve the desired results.
Deep in human experience is a sense
of excitement and beauty in coping
with the extremes of wind and rain
and heat. To be sure, their enjoyment
does not always offset the discomfort
and suffering that lead men to commonly adjust their clothing, dwellings,
transport and other practices to curb
the effects of weather. Yet in the driving power of a winter blizzard or the
sudden flash of summer lightning
there are dramatic reminders of the
elemental forces with which the human race constantly is striving to find
its place. No presently conceivable
program of weather or climate modification could eliminate these extremes. A beginning at changing storm
or lightning nevertheless raises the
question of how far the human spirit
is enriched by the uncertainty and
wonder and exhilaration that come
with the restless, violent movements
of the atmosphere. Any effort to assess the social consequences of
weather and climate modification must
give weight to the esthetic and spiritual as well as purely material rewards.
EVALUATINO SOCIAL EFFECTS
The keen interest in precipitation
induction and fog dispersal shows
that their direct results are believed
to be highly beneficial. Certain electric power utilities, airlines, and fruit
growers have invested funds in research and operations directed at
practical modifications. A public utility on the Pacific Coast concluded that
in the drainage area of one of its reservoirs an increase of less than two
percent in annual precipitation would
clearly justify cloud seeding and that
an increase of ten percent for a large
watershed might be worth $200,000.
An airline has estimated that the immediate benefits in reduction of oper86
ating expenses from fog dispersal in
an intermountain area were at least
five times the seeding costs. Obviously, if a farmer thinks he may increase his per acre wheat yield from
seven to eight bushels by rainfall induction or hail suppression at a cost
of a few cents an acre he will be
strongly inclined to take the risk of
the expenditure even though the resuits are in doubt. It has been calculated that the estimated mean annual
losses of $250,000,000 from hurricanes
might be reduced by as much as one
third if only modest reductions in
storm intensity or slight changes in
storm paths could be achieved. Op portunities for direct, beneficial effects in the economy are immense insofar as genuine modification can be
managed with confidence. The methods for computing such direct benefits
are relatively well developed.
In the sphere of human activities,
the potential effects of modification
on the quantity, timing, and geographic distribution of production and
transportation are particularly striking. But in evaluating the social effects
of weather modification it is not
enough to trace them through the technological aspects of production activities. Behavorial responses and their
relation to the impact on social organization and process must also be identified. Because weather modification
involves costs and may preclude alternatives, its possible results must
be compared with achievements obtainable through alternative ways of
dealing with the vagaries and averages
of weather phenomena. Man adjusts
his activities to weather in countless
ways and constantly is devising new
ones. The evaluation of fog dissipation requires not only the measurement of benefits and costs at the airport and in airline operations, but the
assessment of the benefits and costs
from installing equipment which could
land aircraft notwithstanding fog or
from re-routing traffic on the ground
and in the air.
Improved weather forecasts are one
major alternative to weather modification. Sometimes they may complement each other, but in many instances
an accurate forecast with sufficient
advance warning, if accompanied
by other measures, would reduce or
even eliminate the gains from altering
a weather extreme. Thus, as much as
15-20 percent of flood losses may be
eliminated in certain areas, if there is
sufficient notice, without changing the
character of the flood or of the pre87
cipitation producing it. Severe crop
losses from drought may be reduced
by alternate cropping if the drought
can be predicted sufficiently far in
advance. Traffic can be re-routed
around airports which will be closed
by fog. Perhaps no industry is more
carefully prepared to take advantage
of a forecast of icy or freezing weather
than is the public utility industry
which can move promptly to cope
with weather emergencies. Inaccurate
forecasts also may cost heavily in
damages.
Even in the absence of significant
forecasting improvements, there are
many other means of cutting down
dislocations caused by weather. In
areas where drought occasionally
brings acute crop losses, the social
impacts may be curbed by readjustment in cropping patterns, by breeding or selecting drought resistant varieties of plants, by supplementing the
water supply, by insurance schemes,
and by a variety of other actions, some
of which depend upon further scientific research for their perfection. A
similar range of solutions applies to
dislocations caused by hail, excessive
rain, fog, and lightning.
To be realistic, measurement of the
benefits and cost of modification, forecasting, or any of the other alternatives
must take into account the likelihood
that if certain of them are pursued
consistently, the structure of the economy will change so that it becomes
less vulnerable to dislocation by
weather. In drought areas a reorganization of farming practices might
lead to agriculture which would be
less vulnerable to the recurring dry
periods. Or, a continuing program of
cloud seeding, if practicable, might
raise the mean rainfall sufficiently to
encourage a major revision in type of
farming. This, in turn, could shift the
service functions of nearby urban centers.
Without any conscious modification
of weather, the sensitivity of human
activity to weather may be reduced,
as when air conditioning or insulation
of utility lines renders an area less
susceptible to extremes of temperature. During 1929-1962, the yield of
corn in the Corn Belt increased in several steps related to the technology
of seed, cultivation, and fertilization,
but during the same period the variation in yields due to weather appeared to decrease. 2 That is, the crop
production became less susceptible to
weather dislocations. In these and
other ways estimates of direct im88
pacts of weather modification must be
corrected for longer-term structural
adjustments.
Research relating to the social impact of weather on human affairs
would prove fruitful even if no form
of weather or climate modification
were ever to be achieved. Deepened
understanding of geographic relationships among weather characteristics
and the economic system would be
bound to aid in intelligent decisions
by both resource users and public
agencies in agriculture, transport,
manufacturing, and other sectors of
the economy. The kind of refined
knowledge about crops and rainfall,
or air transport and fog, or forest
growth and lightning which would be
essential to careful estimates of social
impacts of weather modification would
be required for estimates of the sensitivity of the economy to weather,
or for improvement in efficiency of
those activities by other means.
One fundamental question deserv
ing scientific attention is the degree
to which climate already has been
altered or may be altered in the future
inadvertently by the hand of man. To
the extent that either rural or urban
climates have been so modified, the
type and distribution of human activity may be expected to reflect some
readjustments that now are taken for
granted. Urban climates have undergone measureable change in temperature and air quality. The precise
amount still is in doubt. While few
modern societies are so delicately adjusted to rain or its invocation as are
certain of the organizations and social
controls of Pueblo culture in the
Southwestern United States, all of
them involve many adaptations.
Whether the relations of weather
to human activity are isolated over a
few days or many years, they obviously are different from one sector
of society to another. The downpour
which fills a New York city reservoir
washes gullies in a farmer's field; the
hurricane which disrupts a Florida
shopping center carries water to a
nearby Everglades wildlife refuge. If
it is assumed that there is any effect
upon processes elsewhere, the differential results become even more
marked. Were cloud seeding to have a
"rain shadow" of lowered precipitation or were hail suppression to reduce rainfall to the leeward, the complications would multiply. If it were
to be shown that cirrus cloud formation encourages smog conditions, then
the health and heat budget of a metro89
politan area might be affected by airline operations upwind. A map showing the area where weather elements
are altered presents only a part of the
picture; it must delimit the extent of
effects felt in nearby towns or in distant markets.
These impacts are made especially
difficult to measure because people
may differ in their perception of
weather conditions and of man's effect upon weather. Just as many city
dwellers in the path of a hurricane
are unable to act rationally on the
warning of high winds, so people in
an area of weather modification may
for a variety of reasons fail to take
advantage of a changed condition. On
the other hand, a farmer may act as
though the weather is being modified
even when scientific verification is
lacking. In either case, the estimate
of the individually and socially rational solution does not turn out to
describe what people in fact do. A
workable public policy is based on
prediction of what they will decide in
practical situations. The uneasy suspicion of a nation that it is suffering
from cloud seeding to the windward
is a political reality that must be faced
seriously, whether or not harmful effects are known to occur.
Judgment as to adoption of economically optimum solutions inevitably
is tempered by appraisal of what is
likely to unfold in daily activities
once the alteration is under way. It
may well be that individuals will be
unable to take advantage of the potential benefits of weather and climate
modification unless legal and institutional changes are put into effect.
CONFLICTS OF INTEREST
Even though there is no confident
prediction of the extent to which
weather and climate may be modified
in the future or of the full chain of
impacts from such modification, it already is evident that at least four
types of conflicts may be expected to
arise as soon as a modification technique is shown to be practicable. Indeed, they will arise whenever there
is any slight ground to think it may be
practicable. Substantial groups in the
nation already believe cloud seeding
produces rain and perhaps even rainshadow; their responses to private
seeding operations or government research programs are based on these
beliefs and range from enthusiasm to
hostility.
90
These perceived conflicts are real in
the minds of the people involved, and
they cannot be ignored because they
lack scientific validation. This is particularly true of the conflicts believed
to extend across political boundaries.
Below are examples of possible areas
of conflict.
Research on the techniques of
weather modification is likely to encounter conflict with other research
programs unless there is clear agreement as to the time and place of each
field experiment. Otherwise, operations in the area may cause contamination and thus run the risk of invalidating the observations elsewhere.
A proliferation of weather modification operations could make it impossible to carry out carefully controlled experiments. Were farmers in
the Great Plains to become generally
convinced that cloud seeding could
increase rainfall at critical periods or
could suppress hail, their activities
soon would cover the area so
thoroughly that without regulation it
would be difficult to run experiments
to find out whether or not the operations were in fact effective.
A conflict arises where one group
stands to benefit from weather modification and another to lose. As already noted, this may apply both
within a single area and between two
areas.
There is the possibility of conflicts between groups seeking to modify weather for different purposes or
for the benefit of different areas.
Rather than there being unintended
effects upon other groups from one
seeding operation, there can be direct
conflict over the use of a site or
atmospheric condition.
Public policy should recognize the
probability that all four types of conflict may arise, and should seek to
reconcile each of them equitably. In
that effort its responsibility goes far
beyond arbitrating conflict. It should
seek to prevent victimization, either
of people who mistakenly think they
are gaining benefits that do not exist
or of people who are unaware of damages being inflicted upon them by
others. Without public intervention to
assure that proper records are kept
and the findings are available to the
interested parties, it will be impossible
to determine the true gains and losses.
It may be necessary that the government judge the consequences, pro91
vided it is certain that suitable
information is collected.
In a situation where so much of the
knowledge is speculative, it is important that channels be kept open for
research and for the sharing of research findings. This is especially important where the social effects may
possibly reach across county, State, or
international borders. A policy of passively waiting for the conflicts to arise
will in the long run exacerbate them
by permitting research to be impeded
and by allowing the alledged injuries
to show in tedious inconclusive judicial action or in peremptory legislative fiat. The time to guard against
groundless contention is before it
arises.
A university scientist who is anxious to experiment with cloud seeding
now feels more cautious than might
be socially or scientifically desirable
about launching field work. If he
shows positive effects he or his institution may be subject to damage suits
from those who think they have been
injured by too much rainfall or by too
little or by rainfall at the wrong time.
Even if his results are negative or inconclusive, he still may be open to
legal attack by those who genuinely
feel themselves disadvantaged.
Insofar as practical modifications
are carried out they are likely to result
not only in specific gains and losses,
but in widespread institutional changes
in society. Thus far, the conflicts have
applied to small areas but in the future
they may extend over large areas. The
readj ustments which result therefrom
will call for major changes in policy
and organization as well as for arbitration of competing claims and damages.
DESIRABLE COURSES Of ACTION
AnalYSIS Of SOMI Impacts
Because of the need for determining more precisely the character of
social consequences of weather modification, it is important that any
further government operations and
government supported research dealing with modification be accompanied
by analysis of those consequences. If
the operations are entirely private, it
would be desirable for the public to
underwrite such analysis so that the
social results could be recognized.
In cases where the operations are
in relatively small areas and do not
induce structural changes in the econ92
omy, the methods of measuring impacts may be adapted, with suitable
changes, from Federal experience with
evaluating water development projects. Much useful work has been done
on gauging benefits and costs from a
change in water occurrence. These
methods will not be readily applicable
to such special questions as the assessment of recreation benefits and
the distribution of benefits and costs
outside the target area. Nor will they
be particularly helpful in recognizing
institutional adjustments that would
be prominently involved in sustained
modification operations. The findings
would be rough, but they would give
an idea of the order of magnitude of
results and would suggest problems of
evaluation deserving early attention.
Much can be learned promptly from
studying the economic aspects of legal
conflicts which already have arisen.
If Federal and private agencies are
not ready to undertake this type of
analysis, the National Science Foundation should be prepared to support
it. After a few years, the analysis
might be attempted more selectively.
At present, it should be tried wherever practicable.
ROV18W of MCI SIUMOS
There should be critical review of
the methods followed and of the findings so that the methods might be
improved and in time made uniform.
It would be a mistake at this stage to
attempt to set standards for social
evaluation of weather modification.
At present there is no guarantee that
the analyses of different aspects
could be compared with one another.
Working from the experience with
interagency cooperation in water resource studies, the Foundation should
convene a panel of representatives
from interested public agencies and
from research institutions to examine
analytical methods and to suggest
ways of refining them. The panel
would be expected to appraise methods used for the indentification and
measurement of impacts and the use
of such evidence in evaluating weather
modification and alternative measures.
It could draw heavily from experience
over the past two decades in attempting to gauge the effects of water projects on farming, nearby towns, and
on more distant areas. It would report
its findings to the Foundation and the
interested agencies, then making pub93
lic its evaluations. At an early time, it
might well use the data from one of
the comprehensive river basin studies,
such as the Delaware Basin study, to
test the suitability of the methods in
common use.
Re"Gearch on sociai Enects
The support and encouragement
which the National Science Foundation has given to research on physical
processes of the atmosphere should be
extended to research on those relations between weather and human activity which possibly would be
affected by weather modification. This
should include the nature of external
economies and diseconomies from
modification operations, the consequences of shifts in ecosystems, and
the institutional changes that may result. Methods for measuring changes
in crop production and the losses
from fires are well developed, but impacts on recreation and on biological
communities are rough at best. Many
of the impacts will show in revision
of organization of individual and community enterprises.
One means of stimulating further
thinking about fruitful approaches to
these and related problems would be
to enable a scholar broadly acquainted
with the social sciences to spend a
year examining the field of weather
modification with a view to suggesting
especially difficult or promising lines
of investigation. So little systematic
work has been done to date, beyond
the interdisciplinary exchanges already instigated by this Commission,
that it would be helpful to have a
more thorough appraisal of opportunities. The exploratory studies of
weather information and prediction
by the U. S. Weather Bureau and the
Rand Corporation, and the scattered
economic and geographic investigations of the relation of climate to
farming, commerce, and transportation need to be extended widely. 3
It should be emphasized that virtually all of the research which would
be initiated would, if sound, yield
findings that would be useful in making more efficient adjustments to
weather conditions even if no modification were ever to be practiced. The
same method for estimating the benefits to a manufacturer from a change
in occurrence of rainfall would be
helpful in calculating the gains from
an improved rainfall forecast or from
a technical innovation that would
94
render him less vulnerable to damages
from intense rainfall.
Freedom for EXPOrimenwon
In order to permit field experiments
with methods that do not threaten
seriously deleterious results, it is essential to provide for indemnification
of investigators supported by Federal
funds against damage suits.
ResearcH ON BUIC ReiallORSDIP3
If there were relatively full understanding of the complex relationships
among weather characteristics and
human activity, the task of estimating
impacts of weather modification
would be more nearly straightforward. Lacking such understanding in
all sectors of society, efforts should
be encouraged to discover them. In
the long run, it might be practicable
to develop a model of the national
economy which would be sufficiently
detailed and sensitive to predict the
effects of varying one or more of the
daily weather inputs. The methodological problems are enormous. Measurement of weather conditions other
than precipitation and incoming radiation is difficult in any event. The
analysis must be developed in probabilistic terms, and the present relationship to human activity must be
investigated with sufficient precision
to permit judgment as to the degree
to which prevailing geographic patterns of farming, transportation, industry, and recreation would be
altered in response to a change in
weather characteristics.
In the near future, it would be desirable to explore types of models
which might be used and the data
understanding which they would require. An activity analysis type of
model might well provide a flexible
framework without pre-judging the
nature of relationships to be investigated. An input-output model would
merit investigation but would offer
complications. Whatever the form of
model selected, considerable empirical study would be required in narrow
sectors before its application to larger
parts of the economy would be warranted. Thus, the possible shifts in
cropping and manufacturing locations
would need to be specified for different magnitudes of change in each
weather element. Cautious but vigor95
ous steps should be taken in this direction.
Research on oecision Processes
Both the nature of weather processes and the current knowledge
about them require that most human
decisions as to weather modification
must be made in the face of uncertainty. This imposes special restraints
on public agencies and it increases the
difficulty of predicting how individual
farmers, manufacturers, and others
who are directly affected by weather
would respond to changes in weather
characteristics. There is little evidence
as to how many people would take
advantage of an alteration in weather
even if it could be assured, or that
they would do so in an economically
efficient manner. A flood-plain dweller
may fail to heed an accurate flood
forecast because he does not understand what practical steps he could
take; a farmer may not take advantage
of increased rainfall because conditions of credit or farm organization
discourage him. It appears that people
vary from place to place in their belief
in the effectiveness of weather modification. As in all areas of human endeavor, there is likely to be a lag
between technical knowledge and its
application. Differences according to
culture groups may be expected. Research on the conditions of decision
making in these circumstances would
illuminate discussion of suitable public policy by showing the choices that
are open to public agencies and by
increasing the ability to predict the
ways in which weather users may respond to the unfolding technology of
weather modification. The National
Science Foundation should encourage
such investigations.
Research on IoaOverteot
Modificalons
Although public interest tends to
concentrate on the possibility and
effect of new techniques for conscious
modification of weather, it is desirable to look into the degree to which
past and present human activities
cause inadvertent changes in weather
and climate. Investigations of those
alterations require the collaboration
of scientists working on atmospheric,
biological, hydrological, and social
problems. Historical and archeological
96
evidence may need to be compared
with current geography and with meteorological data. The train of events
between human action and weather
characteristics should be traced with
attention not only to physical alterations in climate, but to resulting modification in the quality of human life.
RECOMMENDATIONS
The Commission recommends:
Steps should be taken to assure
that wherever field experimentation
or commercial operations are undertaken in weather and climate modification arrangements be made to study
the social consequences.
A special panel should be established to exchange and give critical
review to the results of such studies.
The method of assessing impacts
of weather modification should be the
subject of research looking to its refinement and extension.
Freedom of field experimentation
should be supported by providing indemnification of Federally financed
experimenters against damage claims.
Research should be encouraged
on the basic relationships between
weather characteristics and human
activity.
Decision making processes in the
face of uncertainty as to weather
modication and its effects should be
subjected to careful investigation as
a means of increasing the government's ability to predict the results of
alternative policies and methods for
weather modification.
Interdisciplinary study of modifications which man makes inadvertently should be encouraged.
97
FOOTNOTES
1 Symposium on the Economic and Social
Aspects of Weather Modification, July 1-3,
1965. List of participants:
Edward A. Ackerman, Carnegie Institution
of Washington
Jack Barrows, U. S. Forest Service, Department of Agriculture
Marston Bates, Department of Zoology, University of Michigan
Boynton Beckwith, Assistant Director of
Meteorology, United Airlines
Sherman W. Betts, Interdepartmental Committee for Atmospheric Sciences
Carl von E. Bickert, Industrial Economics
Division, Denver Research Institute
Reid Bryson, Department of Meteorology,
University of Wisconsin
Horace Byers, Department of Geophysics,
University of Chicago
Emery N. Castle, Department of Agricultural
Economics, Oregon State University
A. R. Chamberlain, Vice President, Colorado
State University
Marion Clawson, Resources for the Future,
Inc.
Norman Crawford, Department of Civil Engineering, Stanford University
James A. Crutchfield, Department of Economics, University of Washington
Leslie Curry, Department of Geography,
University of Toronto
Donald L. Eberly, Meteorologist, Pacific Gas
and Electric Co.
Robert D. Elliott, President, North American
Weather Consultants
William Garrison, Department of Geography, Northwestern University
Donald L. Gilman, Extended Forecast Division, U. S. Weather Bureau
Lester Goldner, Division of Air Pollution,
U. S. Department of Health, Education
and Welfare
Ivars Gutmanis, Division of Air Pollution,
U. S. Department of Health, Education
and Welfare
Robert L. Hendrick, Senior Research Scientist, Travelers Research Center
James Hibbs, U. S. Weather Bureau, Department of Commerce
Howard Hines, Director, Division of Social
Sciences, National Science Foundation
Leonid Hurwicz, Department of Economics,
University of Minnesota
Paul Julian, National Center for Atmospheric Research
Archie Kahan, Bureau of Reclamation, U. S.
Department of Interior
Robert W. Kates, Graduate School of Geography, Clark University
John W. Kirkbride, Statistical Reporting
Service, U. S. Department of Agriculture
R. Koopmans, Department of Economics,
Yale University
Robert Lucas, Lake States Forest Expt. Station, University of Minnesota
Fremont J. Lyden, Department of Political
Science, University of Washington
Arthur Maass, Water Resources Center,
Harvard University
Marion E. Marts, Vice Provost, University of
Washington
Richard Meier, School of Natural Resources,
University of Michigan
Gilbert F. White, Department of Geography,
University of Chicago
Donald Michael, Institute for Policy Studies
Edward A. Morris, Bronson, Bronson &
McKinnon
Jack C. Oppenheimer, Executive Secretary,
Special Commission on Weather Modification
Allan Pred, Department of Geography, University of California
98
Reginald C. Price, Deputy Director, State of
California, Department of Water Resources
Walter Orr Roberts, National Center for Atmospheric Research
Thomas Saarinen, Department of Geography, University of Chicago
Richard Schleusener, Director, Institute of
Atmospheric Sciences, South Dakota
School of Mines and Technology
Anthony Scott, Department of Economics,
University of Chicago
W. R. Derrick Sewell, Department of Geography, University of Chicago
Bernard Silverman, Meteorologist, U.S.A.F.
Meteorological Lab.
Stephen C. Smith, Department of Agricultural Economics, Colorado State University
Evon Z. Vogt, Curator, Middle American
Ethnology, Harvard University
Andrew Wilson, Department of Geography, University of Arizona
Peter H. Wyckoff, Director, Weather Modification Program, National Science Foundation
The problems of measuring the impacts of
weather modification were examined against
the background of experience with evaluating water management projects with a
group of consultants consisting of Emery
Castle of Oregon State University, Allen
Kneese of Resources for the Future, W. R.
Derrick Sewell of the University of Chicago,
and Stephen C. Smith of Colorado State
University. Useful suggestions also came
from a discussion of social evaluation of
weather modification experiments and operations held in Washington, D. C. on September 20, 1965. Those participating in this
discussion were as follows:
Gilbert F. White, University of Chicago,
Chairman
Keith Arnold, U. S. Forest Service
Lowell Ashby, Department of Commerce
Jack Barrows, U. S. Forest Service
Robert Cain, National Science Foundation
Emery N. Castle, Oregon State University
Frank Hersman, National Science Foundation
James Hibbs, U. S. Weather Bureau
Howard Hines, National Science Foundation
H. R. Josephson, U. S. Forest Service
Allen Kneese, Resources for the Future
Karl Lee, U. S. Bureau of Reclamation
Hoyt Lemons, Department of Defense
Jack C. Oppenheimer, National Science
Foundation
Truman Price, Department of the Interior
Louis Quam, Office of Naval Research
Stephen C. Smith, Colorado State University
Harry A. Steele, Department of Agriculture
Peter H. Wyckoff, National Science Foundation
The question of how the basic relations
among weather and economic activity might
be investigated through a comprehensive
model was outlined by Edward A. Ackerman of the Carnegie Institution of Washington and was the subject of a special review
by John A. Edwards of Oregon State University.
2 Lawrence H. Shaw and Donald D. Durost, "The Effect of Water and Technology
on Corn Yields in the Corn Belt, 1929-62,"
Agricultural Economic Report, No. 80, Washington: U. S. Department of Agriculture,
1965.
R. R. Rapp and R. E. Huscke, Weather
information: Its Uses, Actual and Potential,
Santa Monica: Rand Corporation, 1964.
Memo RM-4083-USWB U. S. Weather Bureau, The National Research Effort on improved Weather Description and Prediction
for Social and Economic Purposes, Washington, 1964.
99
The drawing of conclusions as to
the legal and legislative aspects of
weather modification is hampered by
uncertainty as to the scientific capabilities in the field. If one possessed
or seemed likely to possess in the near
future the technological capability of
ordering weather, the ramifications to
our society and hence to our legal
system would be enormous. Even a
limited capacity to modify weather
would pose problems of great complexity. The nature of these problems
is illustrated by what might result if
the present experiments in the "disarming" of hurricanes are successful.
At first blush one would suppose that
no one could object to the dissipation
of destructive storms such as hurricanes. However, there seems to be at
least some opinion that a substantial
amount of the rainfall in the Northeast comes about as a result of hurricane activity. It might, then, turn out
that hurricanes are a necessary part
of the distribution of rainfall in a substantial section of the United States.
Assuming both the power to dissipate
hurricanes and the need for rainfall
in the Northeast, how is the decision
between the risk of catastrophic
storms and the ending of the drought
to be made?
Similarly difficult problems of choice
will be posed by even the limited
capability of precipitation induction
now visualized. In a sense, ability to
control the atmosphere may create
more problems than it solves. For nations as well as individuals the availability of alternatives may turn out
to be more disruptive than the hardships of want.
Given the present state of the art,
extended speculation as to the necessary responses of the laws would seem
unwarranted in a report of this kind.
The temptation is strong to put aside
In considering this facet of the problem
the Commission addressed questionnaires to
the 50 state governments and to the 64 perSons OF organizations (including 7 Federal
agencies) who have been conducting weather
modification research activities or commercial operations. The National Science Foundation contracted with the Southern Methodist University School of Law to have Prof.
Howard J. Taubenfeld undertake in cooperation with the Commission's Executive Secretary, Jack C. Oppenheimer, Esq., a survey,
analysis and summary of the data contained
in the responses. The result is the report to
be published by the NSF in January, 1966,
entitled "Weather Modification: Law, Controls, Operations" (see the Appendix). This
chapter is in large part based upon this
study. Acknowledgment is also made to the
helpful suggestions of NSF General Counsel
William J. Hoff, Deputy General Counsel
Charles B. Ruttenberg, and attorney Joseph
R. Schurman.
LEOAL AND
LEOISLATIVE
ASPECTS
100
the legal question until the science
and technology have developed a little
more. On the other hand, with the
apparent ability to modify weather
intentionally, albeit to a limited extent, and since it is not certain that
efforts do not result in some unintended modifications, one cannot
wholly dismiss the problems. Moreover, whatever the scientific truth may
be, weather modification activities are
being conducted and many people
believe those activities have effects
both beneficial and deleterious. Indeed, some twenty-two states have
already enacted legislation dealing
with those activities. The result is
that the law is already involved with
weather modification in many ways,
so that for better or worse consideration must now be given to some of the
legal aspects of weather and climate
modification.
The existing involvment of weather
modification with law is, broadly
speaking, of two kinds: (1) the body of
rules governing the responsibilities
and liabilities of weather modifiers (or
those who employ their services) to
other members of the public; and (2)
regulation by government (most often
by the states) of weather modification
activities.
Weather modification activities can
result in two more or less distinct
kinds of injury to members of the
public. The first kind is damage caused
by destructive weather conditions
such as flood, hail, hurricanes and the
like. Damages attributable to such
conditions, assuming satisfaction of
other prerequisites to recovery, would
be compensable under traditional
standards. The second kind would
result from the change in climate of a
particular locality, e.g., lowering or
raising the level of rainfall in a locality below or above that which would
have fallen but for the modification.
Assuming that the level which would
have fallen naturally could be established, damage could be of widely
diverse kinds; from the blighting of a
resort owner's season to the ruining
of a particular crop.*
Although liability for weather modification activities, and "property interests in weather," have been the
subject of a good deal of speculation
in the legal literature, there have been
only six lawsuits in which the questions have been litigated. Of these,
three were suits by nearby land-
* The categories are not mutually exclusive. Drought, for example, might belong to
both.
101
owners seeking damages or injunctive
relief on account of floods allegedly
caused by weather modification activities. In two of the cases the trial
court denied relief on the ground that
no causal connection between the activities and the floods had been established. The third resulted in a jury
verdict for the defendant weather
modifier.* The other three suits
sought injunctive relief against interference by the weather modifier with
the plaintiff's property rights in
weather. In one, a suit by resort owners against the City of New York, the
New York court held that the public
interest in ending a prevailing drought
outweighed the resort owners' interest
in good weather. In another, the only
decision against the weather modifiers, a Texas court granted an injunction against hail suppression activities
carried on by farmers in favor of
neighboring ranchers who wanted precipitation in any form, including hail.
The last of the suits is still pending in
Pennsylvania .**
This handful of cases does not, of
course, provide a firm basis for predicting how the law will develop. The
cases do, however, provide food for
thought about a number of aspects of
the problem, not the least of which is
the preview they afford to the kinds
of conflicts one can expect if largescale weather modification becomes a
reality: resort owners against city
fathers; ranchers needing precipitation of any kind against farmers wanting to suppress hail; public utilities
fearing ioss of hydroelectric power
against homeowners fearing disastrous
floods because of the creation of destructive weather conditions.
The chief obstacle to recovery for
damage most likely will be the problem of proving a causal connection
between the activity and the damage.
It should be stressed that legal causality and scientific causality are two
markedly different things. It is quite
possible, as the Texas decision underscores, that liability could be imposed
in circumstances which might not justify the scientist in finding that a
causal relationship existed.
Assuming that the requisite causal
connection can be established, the
* The case was based on claimed negligence and the jury verdict could mean
either that no negligence was found or that
no causal connection was found between
the acts complained of and the damage.
** In addition to these actions there is a
pending criminal proceeding against weather
modifiers for violation of a municipal ordinance prohibiting such activities.
102
next question is whether the injury is
legally compensable. This could depend on the applicable rule of liability, i.e., whether the actor would be
liable only in the case of fault, negligence or some more reprehensible
conduct, or in the absence of fault
under a rule of strict or absolute liability. The applicable rule might in
turn depend on the nature of the actor; whether he is a private operator,
government contractor, or the government itself. There is not much point
in speculating at this time as to the
likelihood of a particular rule of liability's being adopted. Suffice it to say
that if a causal connection could be
established, imposition of tort liability
on one theory or another would seem
likely.
Where the injury claimed is the reduction or raising of the precipitation
level, a substantially different question is involved. The answer will turn
on whether or not a person is held to
have a property interest in a particular kind of weather. It is much too
early to tell how the law will answer
the question of who owns the clouds.
A number of possible theories have
been advanced based on supposedly
analogous situations. The right to
clouds has been compared to the right
to control airspace over one's land;
to the right to acquire wild animals by
reduction to possession; to rights in
water courses, or percolating, or diffused surface waters. The pertinence
of some of these analogies is more apparent than real. Rights to airspace,
to the extent they are recognized, are
justified as necessary to protect enjoyment of the underlying land. The
relationship between the underlying
land and particular clouds passing
overhead, however desperate the need
for water may be, is quite different.
The considerations bearing on the
award of control over clouds are not
all the same as those supporting the
rule as to animals. A watercourse connotes a stream flowing in a reasonably
definite channel with distinct parcels
of land bordering on the stream. In
the Eastern United States, to the extent that property rights exist, they
arise by virtue of the ownership of
the bordering land, a circumstance not
present in the case of clouds. And the
rule of most Western states giving
rights to surface water to the first to
appropriate it could lead to chaos if
applied to water in the atmosphere.
Problems of percolating waters, i.e.,
all subsurface waters other than those
in underground streams, are most
103
nearly analogous. But, here again
rights, to the extent they exist, are
based on ownership of the surface
land. This does not mean that there
are not valuable lessons to be learned
from the development of water law.
The adjustment of competing interests, and the handling—especially in
the Western States—of the problem
of scarcity of vital natural asset give
valuable insights. When all is said and
done, however, the problems of
weather and climate modification are
infinitely more pervasive and complex
than those of water and should be
decided on their own merits rather
than on the basis of wholly or partly
inapt analogies.
The two cases which have posed
the question of "property rights in
weather" have reached different results, at least on the surface. In New
York, the court, while impliedly conceding some interest of the resort
owners in "good weather," felt that
their interest was outweighed by the
interest of the community in ending
a drought. The Texas case, on the
other hand, held that the complaining
ranch owners had a "natural right to
such precipitation (from clouds over
their land) as nature chooses to bestow." Carried to its logical conclusion this decision would make possible
the barring of any weather modification activities except over one's own
land. It should be emphasized that the
relief sought in these cases was injunctive, and that conceivably one or
both cases might have come out differently if, instead, damages had been
sought. That courts would be naturally reluctant to enjoin a municipality's efforts to end a drought because
a resort owner's good weather was
threatened does not mean that in an
appropriate case they would not require the community to recompense
the resort owner.* The "natural rights"
theory of the Texas decision, while a
sufficient basis for enjoying any interference, does not offer much hope for
an award of damages in the light of
nature's well-known unreliability. If,
on the other hand, one measures the
Texas decision by the New York test
of balancing the interests of the parties concerned, it may represent a not
so unreasonable vote for the status
quo as between the competing claims
of ranchers and farmers.
Interesting as these isolated decis-
* In the actual case, the court found that
the experiments by the city would not interfere with the resort owners' business to
an appreciable extent.
104
ions may be, one cannot begin to discuss rights in weather meaningfully
until the capability for control becomes clearer. If weather modifications of significance become scientifically feasible, the implications to
society and law will be such as to
require a rethinking of many legal
concepts. Legislation far broader than
that suggested below will be needed
to order relationships between the
various interests, private and governmental, in the light of the new capability. In short, it is premature to make
recommendations about the rules of
law governing "property rights in
weather" or the liabilities of weather
modifiers for damages found to have
been legally caused by their activities.
It is not, however, premature to
make recommendations about one aspect of tort liability. This is with
respect to indemnification of persons
engaged in weather modification research activities on behalf of the gov ernmen t.* A strong argument can be
made that persons who carry on government-sponsored research activities
should be protected against liability
claims; and that members of the
public who are injured as a result of
such activities should receive adequate compensation. In most respects
the problem is not materially different
from the case of other hazardous government activities. The nature of that
problem and the possible solutions
have been much discussed in recent
years and will be touched on only
briefly.
The most recent study of indemnification was conducted by the Legislative Drafting Fund of Columbia
University for the National Security
Industrial Association, under the direction of Professor Albert J. Rosenthal of the Columbia University
School of Law. In the report, Catastrophic Accidents in Government
Programs, the authors, although primarily concerned with Defense Department and NASA activities, pay at
least passing attention to weather
modification programs. The recommendations of the report can be taken
as the starting point for consideration
of the problem.
Traditionally, the problem has been
* The problem of tort liability of private
operators may be important insofar as they
are concerned and, indeed, may be important to members of the public to the extent
that there is uncompensated damage for
particular activities. At the moment, however, there does not seem to be any justification for a government program to handle
liability on account of private operations.
105
viewed as one of indemnifying government contractors against liability
for damage caused the public, a!
though of late it is being seen increasingly as one of protecting the public.
However viewed, it is widely agreed
that the problem requires legislative
solution. Specific legislation has been
enacted empowering a number of government agencies to indemnify contractors against liability. Except for
the Price-Anderson Amendment to the
Atomic Energy Act, no satisfactory
legislation to deal with potentially
castastrophic liability has been enacted.
Quite apart from the question of
protection of the public and fairness
to the contractor is the question of
government self-interest in having research performed. In this respect there
are already some intimations that the
problem of liability may have an inhibiting effect on researc h.*
Unless frustrated in administration,
an indemnification statute could provide a satisfactory answer to the problems of contractors.** From the point
of view of the public the protection
afforded is indirect. While government
indemnity ensures payment of a judgment once secured, up to the limit
of any ceiling on liability which may
be imposed, it does not affect the right
of a member of the public to a judgment in the first instance.
Whether the government should go
beyond mere indemnification and
more directly ensure public protection, for example, by enacting a law of
strict liability for contractual activities, is a subject now being debated
in the Defense Department and NASA.
In extending the Atomic Energy Indemnification legislation the Joint
Committee on Atomic Energy specifically called attention to the need for
inquiry into that problem. Not much
point is seen in adding to that discussion. As a general rule a member of
the public injured as a result of government-supported weather modification research should be treated the
same as one injured by DOD or NASA
activities. It is to be hoped that indemnification legislation covering those
agencies and others will soon be en-
* "Introduction to Weather Modification:
Law, Controls, Operations," H. J. Taubenfeld, et al, to be published by the National
Science Foundation in January 1966. See the
Appendix.
** We have discussed the problem in
terms of contractors. It is conceivable that
similar problems would be met in the case
of grantees, and there is no theoretical reason
why they too should not be covered where
appropriate.
106
acted. Weather modification activities
should be covered. It is more important that some protection be afforded
than that equality of treatment be preserved. If no general legislation is enacted, special indemnification legislation for weather modification should
be. Needless to say, this recommendation should not be construed as implying that any causal connection between
particular weather modification activities and injuries to property has been
established. As noted above, legal
cause may be found whatever the
opinions of scientists, and it is the
risk of liability rather than the scientific reality which is important here.
The second area of involvement of
weather modification with the law is
that of regulation. Considering the
small amount of activity in the field,
the amount of State legislation is
rather staggering. Twenty-two States
now have statutes dealing with at
least some aspects of weather modification and others have legislation
under consideration. Most of the
statutes date from the period of the
early and middle 1950's, but a few
have been enacted in the last five
years.
In general, State statutes can be divided into two broad classes: 1) those
the primary aim of which would seem
to be active control of weather modification activities with the collection
and evaluation of scientific information as an important adjunct of control; and 2) those which aim primarily
at the collection and evaluation of
information. In the first and larger
group restrictive laws necessitate a
license or registration for operation.
Where a license is required, it usually
can be obtained only after a statement is filed showing the qualifications of the operator, his financial
responsibility, the nature of the proposed work and the payment of a fee.
Only two of the States list specific
criteria of competence. In one case
the operator must be a professional
engineer. In the other the operator
must be a member of, or qualified for
membership in, the American Meteorological Society. The methods of assuring financial responsibility differ
widely as well. Public notice is often
required before activities can be undertaken. As a general rule qualifications, financial responsibility, etc. are
evaluated by boards and commissions.
At least eight States have special
weather control boards, presumably
with special expertise in the field.
Most States require reports after the
107
conduct of the weather modification
activity.
Several States assert sovereign
rights to the moisture in the clouds or
atmosphere above their land mass.
New Mexico, Louisiana and Colorado
limit weather activities which may
affect other States, although in the
case of the latter two, only on a reciprocal basis. One State, Maryland,
has now barred all weather modification activities for a two-year period.
The Pennsylvania legislature recently
adopted a bill to prohibit all weather
modification activities except research
by universities and the State and Federal governments. The bill was vetoed
by the Governor.
To gauge the operation and administration of these statutes, the Commission sent questionnaires to all States
and all known commercial operators
and researchers active in the field. The
answers to those questionnaires,
which are analyzed and summarized
in the report referred to above entitled
"Weather Modification: Law, Controls, Operations," would indicate that
the effect of regulatory legislation on
weather modification has been slight.
To be sure, there were instances of
dissatisfaction, but little evidence that
existing laws have caused any substantial dislocation to operators. It is
interesting to note that, nevertheless,
there was a widespread agreement
that Federal legislation would be welcome.
For present purposes, the significance of State regulatory legislation
is not so much its past effect but its
potential impact on programs which
may be desirable. Obviously, any legislation which prohibits weather modification activities—if construed to
apply to research as well as commercial activities—could have a serious
effect on desirable programs. State
licensing requirements in some circumstances could place a serious burden
on any experiment crossing State lines,
and most experiments of any size
would be likely to do so. The nature
of the subject, including the likelihood
that the effects of activities will not
be restricted to a single State make it
seem probable that Federal regulatory
legislation will ultimately be needed.
The question of immediate interests is
whether anything needs to be done
now.
At the present time, the only Federal
"regulation" of weather modification
activities is the report form required
to be filed annually by all operators
of whose activities the National Sci108
ence Foundation has become aware.
The report is required pursuant to
the authority of the Foundation under
PL 85-510, "to obtain by regulation,
subpoena, or otherwise, such information . . . as may be deemed necessary
or appropriate . . . to carry out
the program of study, research and
evaluation in the field of weather
modification." This after the fact system of information collection has recently been changed. Effective January
1, 1966, the Foundation adopted a new
regulation requiring that all weather
modifiers keep certain records, and,
in addition, give the Foundation thirty
days' advance notice of any proposed
activity. The purpose of the recordkeeping requirements is, in the words
of the Regulation, "to develop information for use in carrying out the
responsibility of the National Science
Foundation to support a program of
study, research, and evaluation in the
field of weather modification . .
It is too early to tell how the new
regulation will work, and whether its
objective will be accomplished. While
it is conceivable that no additional
action will be necessary, it seems
likely that even for the immediate
future further steps will be necessary.
Fulfillment of the objectives of the
program recommended in this report
requires that research have a very
high priority. This means that State
and local legal rules cannot be permitted to interfere with research objectives. Interference can be of two
kinds. First, the local rules may impose liability for injuries caused by
research projects; the threat of liability may act as a deterrent to researchers. For the reasons set forth above,
it is not believed that the time is ripe
for postulating new rules of liability.
Consequently, the best way of dealing
with the possibility of this kind of
interference is by indemnity or other
protection against liability.
There remains, however, the possibility of direct interference by injunction, either pursuant to a statute or
ordinance forbidding or restricting
weather modification activities, or as
in the Texas case under the courts'
general power to prevent interferences with property rights. It is worth
noting that where timing is important,
even a temporary injunction can have
disastrous effects on a research project. So long as the work is carried on
directly by the Federal government it
would seem to be immune to injunction. If it were carried on by a government contractor, whether a private
109
company or an institution, the immunity would be much less clear. And,
where research is carried on pursuant
to grant, there would appear to be no
governmental immunity whatsoever.
Provision should be made to ensure
that all properly conducted experiments including those conducted by
contract or grant should be immune
to local interference.
A somewhat different problem is
posed by the possibility that some
weather modification activities may
physically interfere with government
activities. As pointed out elsewhere
in the report, the nature of cloudseeding experiments is such that there
is a real possibility of contamination
by other seeding operations in the
same general location. Such contamination can be expensive and scientifically catastrophic in view of the
limited opportunities available for
some kinds of research. A part of the
problem can probably be taken care of
by the proposed Foundation regulations requiring advance notice of all
operations. But advance notice may
not be enough; in some cases it may
be desirable to stop the interfering
weather modification activity. If those
activities are carried on by other researchers, whether or not Federally
supported, persuasion will probably
be sufficient. Where commercial operators are involved persuasion may be
less effective. In either event, power
to halt interference should be available where necessary to protect the
integrity of government operations.
The power does not exist today. The
power to halt interference and the immunity from state interference need
not be unlimited. Room can be left for
reasonable accommodation of the
needs of local governments. But, priority of the Federal program must be
established.
One other suggestion for regulation
—that private operators be required
to evaluate their operations—should
be discussed. Because of the nature
of research in weather modification,
and the nature of the problem of evaluating results, it would be particularly
desirable to use all experiences including those of private operators. If
full advantage is to be taken of their
experiences, they should be carried on
and evaluated in accordance with prescribed methods of project design,
analysis, etc. Where government contractors or grantees are involved this
should not pose any great difficulty.
The case is different with private
operators where, among other objec110
tions, the increased cost of operation
might be prohibitive. For the moment
it is felt that no such requirements
should be imposed on private operators, but the situation may change
rapidly. In the meantime, study should
be given to the legal obstacles, if any,
to such a requirement, and the desirability or necessity of government
financing of the evaluation.
Thus the Commission recommends
that the Federal Government by appropriate legislation be empowered to:
delay or halt all activities—public or private—in actual or potential
conflict with weather and climate
modification programs of the Federal
government, whether carried on by the
government itself or by its grantees
or contractors;
immunize Federal agents, grantees, and contractors engaged in
weather and climate modification activities from State and local government interference; and
provide to Federal grantees and
contractors indemnification or other
protection against liability to the public for damages caused by Federal
programs of weather and climate
modification.
In view of the state of the art, it
would seem appropriate to limit regulation to the least amount consistent
with achievement of the objectives of
the program. The Commission's recommendations are deliberately restricted
in scope. It would be well to note,
however, that as the art develops, and
as weather and climate modification
activities increase, comprehensive regulation seems inevitable. Such regulation will probably require the setting
of minimum standards of competence,
and perhaps financial responsibility,
for all operators and the establishing
of some authority for deciding between competing claims for priority.
What the proper amount of regulation
is will depend on how rapidly the field
expands. It may be that the findings
of the NAS Panel will stimulate very
rapid expansion of field programs. The
regulatory program may well have to
keep pace.
Whatever regulation is decided
upon must be national in scope. While
it may be that some activities will
have effects limited to the boundaries
of a particular State, it seems likely
that such cases will be exceptional.
Whether there will be any need for or
utility in simultaneous regulation by
the States will depend on the nature
111
of the Federal program and the devel- Domestic regulation, whether
opment of the technology. It may be wholly national or mixed national and
that regulation at the national level state, should not be regarded as all
will be sufficient, or indeed, that ex- that is necessary. Global phenomena
clusive Federal control is demanded. are involved in the weather and effecSuch questions can be left for the tive regulation must ultimately be
future. For now it would not appear global in character. It is to be hoped
necessary to intrude on state pro- that as the needs of an adequate regugrams, provided only that they do not latory system become defined, efforts
have the effect of impairing the Fed- will be made to establish the system
eral effort. on an international basis.
With respect to the weather modification prohibition bill recently vetoed by the Governor of Pennsylvania and referred to on page 108 this chapter,
subsequently on November 9, 1965 the Governor
signed into law Act No. 331 granting to each of
the counties the optional authority to prohibit any
weather modification activities deemed detrimental to a county's welfare.
112
WEATHER
MODIFICATION
AND
INTERNATIONAL
RELATIONS
The major impulse behind the development of a national program of
weather modification arises in association with problems encountered
within the United States. Efforts to
develop or apply weather modification
techniques on the part of governmental agencies, research institutions and
commercial enterprises have focused
mainly on domestic problems and
have been carried out primarily within
the borders of this country or over the
open seas. It might seem, therefore,
that weather modification had little to
do with international relations or considerations of foreign policy. This
would, however, be an erroneous view.
The active interest in the subject displayed in foreign countries and in international organizations, the international impact of projected research
and operational programs and the contribution which a weather modification
program could make to the foreign
policy objectives of the United States
are indicative of the international implications of this area of scientific
effort.
The evidence before us suggests
that attempts to augment rainfall over
areas of a few thousand square miles
may have effects that may extend
many miles downstream from the site
at which the seeding agent is introduced into the atmosphere—clearly
far enough in some instances to cross
national boundaries. The probability
of success in such activities is now
sufficiently high to warrant immediate
attention to their implications for international relations. The possibility
of downstream diminution of rainfall
—though small—cannot be completely
ignored, with even greater implications for international problems in
equitably sharing a natural resource.
If the political problems are sufficiently near at hand to suggest Federal, rather than State, regulation
domestically (see the chapter in this
report on Legal and Legislative Aspects), it is not too early to give some
attention to the international political
problems and opportunities.
Rudimentary attempts have already
As a basis for the preparation of this
chapter of the report, members of the Commission, in addition to reviewing the limited
literature bearing upon the subject, consulted with a number of government officials and persons in private life experienced
in international affairs and particularly international scientific programs. The Commission also obtained a report on international relations and weather modification
from Leonard E. Schwartz of Operations
and Policy Research, Inc. of Washington,
D. C. See the Appendix.
113
been made to influence the intensity of
hurricanes over international waters.
Although no success has been claimed,
the probability of success in future
attempts is somewhat greater than
zero. A similarly small probability of
success will be applicable to attempts
to influence the direction of movement of a hurricane when those attempts are made. Not much imagination is required to envision the kind
of international political problems that
might ensue should those small probabilities of success be realized.
Even graver problems, though much
more remote, arise in the matter of
possible modification of the climate
over areas of subcontinent size. The
fundamental unity of the global atmosphere and the close coupling and interaction that exist among the major
components of planetary wave are
well recognized characteristics of the
atmosphere. The situation in which a
drought of many months duration in
one section of the United States occurs
concomitantly with above normal rainfall in another section can be generalized. If one day it turns out to be
possible to exercise meaningful modification of the weather or climate over
one region of the earth's surface it is
quite possible that a compensating
alteration will take place in the atmosphere over some other region.
There is the very long-range matter
of influencing the world-wide climate
either by conscious intervention
through exploitation of triggering
effects or inadvertently as the multifarious activities of an expanding
population exert an ever more profound influence on man's natural environment. In the latter case, issues
arise that transcend national considerations and affect all mankind.
The salient points can be summarized:
For each identifiable class of
meaningful modification of weather
or climate (e.g., dissipation of supercooled fog, augmentation or redistribution of rainfall, suppression of hail,
altering the intensity or causes of hurricanes, large-scale modification of climate), there exists a probability of
success. The probabilities range from
very high for supercooled fog through
something greater than 50 percent for
rainfall, down to very low but greater
than zero for large-scale climate
effects.
The implications for international
relations of success in each class of
weather and climate modification depend on the particular class in ques114
tion. For example, the implications are
minor in the case of supercooled fog,
quite significant for rainfall, large for
hurricanes, and very large indeed for
world climate.
3. In contrast to the situation existing a decade or so ago, now at hand
are the scientific and technological
tools to explore the limitations and
practical applications of each class of
activity.
INTERNATIONAL PRODRAMS
RELATED TO WEATHER
MODIFICATION
International cooperation in the
study of the earth's atmosphere has
been carried on for many years
through both governmental and private agencies. Official international
activities in this field have been centered in the World Meteorological
Organization (WMO) established in
1947 primarily in connection with the
collection of weather data for forecasting purposes. In the non-governmental area, the International Council
of Scientific Unions (ICSU) and its
constitutent bodies have played a central role. Such large world-wide programs of scientific research as the
International Geophysical Year (ICY)
and the International Years of the
Quiet Sun (IQSY) have not only widened man's knowledge of the factors
bearing upon the atmosphere and consequently weather and climate, but
have also demonstrated new and
imaginative patterns of international
cooperation.
The United States Government has
for some years participated in bilateral
cooperation with other governments
in the field of meteorology with emphasis upon weather forecasting. The
agreement with the Soviet Union announced in October 1964 for the exchange of meteorological satellite data
between Moscow and Washington
over a special twenty-four hour communications link is one of the most
recent and interesting examples of this
bilateral cooperation. An example of
bilateral cooperation having worldwide ramifications is the TIROS
weather satellite program developed
by the U. S. Weather Bureau and the
National Aeronautics and Space Administration. Under this program the
United States is now making available
valuable meteorological data collected
by a TIROS satellite and immediately
115
transmitted to receiving stations in
foreign countries over a specially devised communications system.
Multilateral international activities
more directly related to the problems
of weather modification were stimulated by President Kennedy's speech
to the General Assembly of the United
Nations in September 1961, in which
he appealed for international cooperation in the peaceful uses of outer
space. The Assembly responded by
adopting Resolution 1721 (XVI) in
December of that year, Part C of which
contained recommendations for advancing the state of the atmospheric
sciences with a view to determining
the possibility of large-scale weather
modification and for developing an
improved system of weather forecasting. The principal responsibility for
carrying out the necessary studies and
planning with respect to weather forecasting was placed upon the WMO,
while ICSU was subsequently invited
to formulate additional suggestions
for advancing research in the atmospheric sciences. The development of
the improved world weather system
(subsequently named the World
Weather Watch) through the WMO
and of the basic research program
through the ICSU are closely related,
in that the projected system of data
collection and processing will serve
the purposes of both.
Weather modification is thus intimately related to the broader program
of international collaboration in the
atmospheric sciences which has
emerged during the last three or four
years and which consists of the following four main elements:
The program of atmospheric research now being planned in the World
Meteorological Organization and the
Inter-Union Committee on Atmospheric Sciences of ICSU;
The World Weather Watch being
developed through the World Meteorological Organization;
A climatological program aimed
at an improvement in the description
of world-wide climate with a view to
facilitating the better utilization of
land and water resources and ultimately contributing to the objective
of modifying climatic conditions.
Strengthened educational programs to provide the scientific and
technical manpower required for the
overall program.
The scientific community of the
United States has played a major role
116
in the formulation of this program and
is continuing to do so. Moreover, the
U. S. Weather Bureau has had a prominent part in the development of plans
for the World Weather Watch and the
program of atmospheric science research being developed by the WMO.
The interchange of ideas and the close
collaboration that has been effected
between scientists in the government
and in private institutions—and between those primarily engaged in research and those occupied in governmental weather services—have proved
important in reflecting the views of a
broad cross-section of the scientific
community and in assuring that the
requirements of both research and
operations receive proper and adequate attention. It is hoped this complementary relationship will continue
not only on a national but also on an
international level.
INTERNATIONAL REQUIREMENTS
OF RESEARCH
The broad program of research outlined in earlier chapters of the Commission's report demonstrates the need
for approaching problems of weather
and climate modification with a strong
emphasis upon international cooperation. To be sure, much of the research
to be undertaken will be carried out
within the borders of the United
States. Nevertheless, the extensive and
significant work that is being done in
other countries underscores the need
for promoting the international exchange of data and research findings
for the purpose of maximizing their
usefulness. The need for international
collaboration in the actual planning
and conduct of research activities may
be expected to increase as research
moves out of the laboratory and into
the realm of field experiments associated with the study of the dynamics
of climate, the establishment of a
global weather observation network
(which supports the numerical simulation program) and the investigation
of other aspects of the general atmospheric circulation. Proposals for research already advanced, such as those
involved in the World Weather Watch,
involve a reliance upon widespread
international collaboration in data collection. They require the selection of
areas of study far removed from the
United States, such as land and sea
areas in the southern hemisphere and
the polar regions. Both the basic
117
knowledge gained in such investigations, and its practical application to
weather forecasting and weather and
climatic modification, will be of great
interest to many countries. The technological and human resources required for the conduct of this type of
research are far beyond the capability
of most countries to provide individually. Increased international collaboration in such endeavors would seem,
therefore, to be inevitable.
Looking into the future to the time
when field experiments with weather
or climate modification are expanded
in scope and number and involve actual attempts to introduce changes in
the atmosphere, some form of international collaboration will be essential
in the planning and execution of projects that may have an impact not only
upon the immediate localities but on
areas in other countries and even upon
other continents distant from the scene
of work. It is possible situations of
this sort may arise in the near future
if an expanded program of field experiments in cloud seeding is undertaken in areas near the northern or
southern borders of the United States.
An expansion in experimentation with
tropical hurricanes may also present
international complications heretofore
avoided.
WEATHER MODIFICATION AND
WORLD POLITICS
In the present stage of world affairs
any scientific advance contributing
significantly to man's ability to affect
the natural environment has a bearing
upon the political relations among
states and the quest for peace and
security. The importance to military
operations of a capability for modifying local weather conditions is obvious.
Moreover, in view of its potentially
spectacular character and its important consequences for the welfare of
all nations, a capability for significant
weather modification would augment
the prestige and political influence of
the country which first achieved it.
Nor can it be overlooked that an
ability to control weather conditions
could have an effect upon international
conflicts apart from the range of
strictly military operations. The effective precipitation of water from moisture-laden clouds over the territory of
one State to the real or imagined detri118
ment of an adjoining State normally
dependent upon the same sources of
atmospheric moisture, could easily
serve to stir up international controversies and exacerbate existing tensions. Even the remote possibility that
a nation might develop a capability of
using weather modification measures
to damage the economy and civil
population of another country must
be recognized.
RELATION TO U.S. FOREION POLICY
It should be clear that a long-range
program of weather and climate modification can have a direct bearing upon
the main purposes of American foreign
policy. It can contribute to defending
the security of the United States and
other nations of the free world. It can
aid the economic and social advancement of the developing countries,
many of which face problems associated with adverse climatic conditions and serious imbalances in soil
and water resources. It can serve as
a new and widening area for the development of common interests with
both friends and present adversaries,
and thus stimulate new patterns of
international cooperation.
The challenge and the opportunity
presented to the world community by
the prospect of man's achieving the
ability to modify the atmospheric environment form one of the most exciting long-range aspects of the subject.
It involves the possible acquisition of
a new and enormous power to influence the conditions of human life. The
potentialities for beneficial application
are vast, as are also the potential dangers. It is in the long run essential to
develop political and social controls
over the use of this power which will
maximize the opportunities for its constructive, peaceful use and minimize
the factors which tend to involve it in
the tensions and conflicts inherent in
human society.
The very fact that the development
of a capability for influencing the atmospheric environment is still in its
infancy should widen the opportunity
presented by this scientific endeavor
to develop attitudes and patterns of
collaboration which can contribute
not only to the achievement of the
practical technological goals, but also
to the relaxation of international tensions. Vested national interests in
technological achievement in weather
modification are still limited. In contrast to the field of atomic energy and
119
developments in outer space, no nation
has yet forged a weapons system in
the field of weather or climate control
that can threaten the security of another country. Moreover, while political influences have by no means been
totally absent in even the restricted
international programs that have so
far been initiated in the atmospheric
sciences, no major political issues
have yet been raised on which rigid
and irreconcilable positions have been
taken. Small beginnings in collaboration on problems of weather and climate have already been made which
could prove useful in helping to build
the habit of cooperation and in stimulating a pragmatic recognition of the
material advantages to be derived from
that approach.
INTERNATIONAL IMPACT OF
U.S. PROORAM
The growing recognition of the efficacy of certain cloud-seeding practices,
coupled with an increased public demand for rain-making operations stimulated by a series of dry years in the
United States, will no doubt produce
a greatly enlarged interest and activity
in connection with weather modification. Field experiments conducted both
by governmental and private agencies
may be expected to expand. Commercial operations may well increase.
Larger public appropriations for
weather and climate modification purposes will be sought and probably
made. Legislation dealing with various
aspects of weather and climate modification will be considered and probably be enacted.
An expanded United States activity
in weather and climate modification
cannot fail to have its impact upon
governments and public opinion in
other countries. Questions will arise
as to the exact level of capability
achieved by the United States in affecting weather; the potential benefit or
danger which this power to influence
the atmosphere may imply for other
countries; and the policies and purposes that will guide the United States
in the development and exercise of
this new technology.
120
ORGANIZATION OF
INTERGOVERNMENTAL
COOPERATION
The responsibility for promoting
inter-governmental cooperation and
contacts on the scientific and technical level with respect to weather and
climate modification be recognized in
whatever administrative arrangements
are decided upon for the national program in this field. The close relationship of weather modification to other
programs and responsibilities of the
government would, of course, require
an adequate system of inter-agency
coordination in connection with
United States participation in international weather and climate modification activities.
The formal adoption of a policy of
international cooperation for the
peaceful development of weather and
climate modification would confirm
and support the limited but significant
cooperation now being extended by
governmental and private agencies of
the United States in this field. It should
provide an impetus for further activities of this sort by the various interested agencies and organizations
through both bilateral and multilateral
channels of contact with foreign countries. The policy decision should also
lay the basis for the planning of future
programs and the anticipation and
study of problems associated with the
international aspects of modification
activities.
The Commission endorses support
by the United States of the World
Weather Watch and the program of
research in atmospheric science being
planned by the WMO and ICSU. As
a further measure of international cooperation, the Commission urges that
if a national laboratory is established,
it be given a mandate to promote the
wide participation of foreign governmental and private institutions in the
development of research programs of
international interest. The successful
execution of this function by a United
States national institution might pave
the way for the future establishment
on a truly international basis of one
or more centers devoted to the cooperative study of the atmosphere and
its intervention in the interests of human welfare.
121
SCIENTIFIC AND TECHNICAL
EXCHANOE
In the basic field of international
exchange of information and technical
cooperation several problems present
themselves. A major limitation affecting both advanced and developing
countries is the shortage of trained
personnel in atmospheric sciences at
all levels. The growing discrepancy
between the advanced and developing
countries in this respect imposes a
further obstacle to genuine international cooperation. Attention should
be given to the question of how greater
emphasis can be given to atmospheric
sciences in existing bilateral and multilateral programs of education and
technical cooperation, and to what
additional measures may be needed
to fill any deficiency.
Encouragement should also be given
to the development of basic research
on the impact of weather modification
measures in foreign countries. Other
chapters of this report have indicated
the need for greater attention to the
biological and economic and social
aspects of weather modification in the
United States. A different set of problems may well be encountered in many
of the less developed countries where
the natural environment and patterns
of economic and social life present
contrasts to those prevailing in this
country. A greater understanding of
the significance of these differences
must precede any attempt to evaluate
the suitability of various weather
modification practices for specific foreign areas and to design appropriate
programs of cooperation. The opportunity for international cooperation in
such research programs is obvious.
INTERNATIONAL LEDAL PROBLEMS
Some form of international regulation of weather modification activities
will no doubt become essential in the
future as research and operational
activities increase in number and extent. One forum for the international
consideration of legal aspects of this
problem, insofar as they concern activities in outer space, already exists
in the legal subcommittee of the Committee on Peaceful Uses of Outer Space
of the United Nations General Assembly. Little attention has yet been given,
122
however, to such basic questions as
the proprietary rights of states to the
atmosphere passing over their territories; the liabilities of states for
damage inflicted upon the adjoining
states as a result of deliberate or inadvertent tampering with the atmosphere; or procedures for advance
notification or consultation regarding
projected weather modification measures capable of affecting other states;
etc. If international regulations are
formulated, the whole question of enforcement likewise comes to the fore.
QUESTIONS OF INTERNATIONAL
ORGANIZATION
Looking even farther ahead, thought
must be given to the types of international organization that will be needed,
and the functions they should perform, if and when operations in
weather and climate modification affecting large continental areas become
feasible. At present international organizations in the field of atmospheric
sciences are of the traditional, general
membership variety with limited functions of information exchange and
voluntary coordination of national
programs. Whether the assignment of
operational responsibility to an international agency should be considered
for the future deserves thought even
at this early date. What new concepts
of international organization suggest
themselves for that purpose and what
new problems of a technical or political nature would be precipitated by
such a plan? Considerable light may
be thrown on these questions by the
experience to be gained in the global
observation program now being
planned in connection with the World
Weather Watch.
Steps should be taken by the United
States, in concert with other nations,
to explore the international institutional mechanisms that may be appropriate to foster international cooperation and cope with the problems which
may be anticipated in the field of
weather and climate modification. The
United Nations and its specialized
agencies (e.g. the World Meteorological Organization) is suggested as a
possible governmental framework. The
International Council of Scientific
Unions and its associated unions (e.g.
the International Agencies of Geodesy
and Geophysics) could be a suitable
123
non-governmental framework for
these mechanisms.
Rarely has a more inviting opportunity been offered for advance thinking and planning regarding the impact
of a technological development upon
international relations. It is hoped that
government agencies, universities, research institutes, centers of international studies, societies of international
law, as well as individuals will take
advantage of this possibility of contributing to the maximum utilization
of the anticipated capability of affecting weather and climate in the interests of peaceful world development.
Progress in the diminution of international tensions and the achievement
of peace will come not so much from
the dramatic resolution of basic international controversies as from the far
less spectacular growth in ways of cooperation and from the widening of
areas of mutual interest among rival
nations.
RECOMMENDEO BASIC POLICY
STATEMENT
The Commission believes that it
would be highly desirable for the
Government of the United States, in
connection with the expansion of its
program of weather and climate modification, to issue a basic statement as
to how it views the relationship of this
new national effort to the interests,
hopes and possible apprehensions of
the rest of the world. The Commission
further believes that emphasis upon
international cooperation in the development of weather and climate modification programs will contribute substantially to scientific and technical
progress and will also serve the national purpose of seeking to build a
peaceful world order.
The Commission recommends the
early enunciation of a national policy
embodying two main points: 1) that it
is the purpose of the United States,
with normal and due regard to its own
basic interests, to pursue its efforts in
weather and climate modification for
peaceful ends and for the constructive
improvement of conditions of human
life throughout the world; and 2) that
the United States, recognizing the
interests and concerns of other countries, welcomes and solicits their
cooperation, directly and through
international arrangements, for the
achievement of that objective. This
124
cooperation should cover both research and operational programs of
interest to other countries. It should
be concerned not only with deliberate
but also inadvertent human interventions in the atmosphere that affect
weather and climate. Such a policy
declaration could be issued by the
President or incorporated in any basic
legislation on the subject of weather
and climate modification which the
Congress may enact.
125
FEDERAL FINANCIAL SUPPORT OF
WEATHER ANO CLIMATE
MODIFICATION
Present Support
The chart set forth below shows
that with the exception of FY 1962 the
total Federal government support of
agency research and development programs in weather and climate modification remained at about the same
level during the first 5 years after the
initial funding of the National Science
Foundation program in FY 1959 and
increased at the rate of 35-407o per
year in the last 3 fiscal years.
Federal Funding of Weather Modification Prrams FUNDINO AND Millions
of ADMINISTRA. Dollars
8
- * 1962 Peak due to l.ómillion increment by ARPA TION o Actual
REQUIREMENTS
2-
o
59 60 61 62 63 64 65 6
FISCAL YEAR
Source: National Science Foundation
126
The table below displays the last weather modification research estabfiscal year 1965 and the current fiscal lished by the Interdepartmental Cornyear 1966 budgets of each of the seven mittee for Atmospheric Sciences
agencies in terms of the six goals for I
(ICAS).
FEDERAL WEATHER MODIFICATION PROGRAM
(millions of dollars)
Fog & Light- Severe
Department Cloud Precip. Hail ning Storm
or Agency Diss. Modif. Supp. Modif. Modif. Other Total
FY 1965
Agriculture - - - 0.14 - - 0.14
NSF - 1.55 - 0.23 - 0.22 2.00
Commerce - - - - 0.10 0.02 0.12
Army 0.16 - - 0.09 - - 0.25
Navy 0.71 - - - 0.20 - 0.91
Air Force 0.25 - - - - - 0.25
Interior - 1.26 - - - - 1.26
TOTALS 1.12 2.81 - 0.46 0.30 0.24 4.93
FY 1966
NSF 0.03 1.22 0.35 0.10 0.10 0.20 2.00
Commerce - 0.035 0.035 0.13 0.32 0.13 0.65
Army 0.16 - - 0.09 - - 0.25
Navy 0.71 - - - 0.20 - 0.91
Air Force 0.26 - - - - - 0.26
Interior - 2.98 - - - - 2.98
Agriculture - - - 0.14 - - 0.14
TOTALS 1.16 4.235 0.385 0.46 0.62 0.33 7.19
127
These tables indicate that the seven
agencies reported to ICAS budget
totals of $4.93 million for FY 1965 and
$7.19 million for FY 1966 in direct support of weather modification.
For purposes of understanding the
relationship of the current support
for weather and climate modification
research to the support for the overall scientific research programs and
services of which it is a part, there
are set forth below tables displaying
the FY 1965 and 1966 total Federal
budget for atmospheric sciences and
meteorological services.
Federal Funds for Atmospheric
Sciences and Meteorological
Services
(millions of dollars)
FY 1965* FY 1966
Aeronomy 110.7 111.3
Meteorology 98.3 116.0
Total Atmospheric Sciences * 209.0 227.3
Total Meteorological Services** 261.2 273.3
Grand Total
Atmospheric
Sciences and
Meteorological
Services 470.2 500.6
* Source: Interdepartmental Committee for
Atmospheric Sciences
** Source: Office of the Federal Coordinator
for Meteorological Services and
Supporting Research
128
Need ior increased suppom
lot Research, Deveiovmeni,
and operanons
The Commission recommends that
the total current FY 1966 budget for
climate and weather modification research of approximately $7.2 million
be increased by 1970 to $20 to $30
million or approximately 5% of the
total current FY 1966 budget of $500.6
million for both atmospheric sciences
and meteorological services. Additional increases of the same order are
needed for basic research and for large
computing facilities, making for a total
increase of $40 to $50 million per year
by 1970.
At present weather and climate
modification research represents less
than 2% of the current budget for the
scientific research programs and services of which it is an integral part.
The foregoing recommendation would
mean that the total budget for weather
and climate modification research
would be maintained at the same rate
of increase of the last 3 fiscal years,
namely 35-40 percent per year, in
order to reach a support level of $20
to $30 million per year by FY 1970.'
Additional amounts will be needed for
underlying basic research activities
and the provision of large computing
facilities.
This recommendation is in recognition of the uncertainties in the state of
knowledge and potentialities in the
field of weather and climate modification and the diversity and magnitude
of effort required to exploit the possibilities which have been discussed
elsewhere in this report. Weather and
climate modification research should
now have a more important role in
research and development in the atmospheric sciences. Large, scientifically designed and controlled field
experiments are needed. Associated
biological and social science research
is desirable to measure the effects of
'These figures include applied research
and immediately supporting basic research
for increasing precipitation by seeding, suppression of lightning and hail, fog and cloud
dispersal and severe storm modification.
They do not include the longer range basic
research studies required for assessment of
advertent and inadvertent modification of
climate.
129
experiments on the ecological and
social systems. Required also are
costly logistics support, aircraft, instrumentation, larger computers, laboratory models of the atmosphere, and
perhaps synchronous satellites and
ecology laboratories.
The Commission recommends that
a new research and development capability be established—similar perhaps to a national laboratory—for the
purpose of providing the necessary
resources of scientific leadership and
logistic facilities necessary in the
mounting of an expanded interdisciplinary program of weather and climate modification.
A national laboratory type of capability is needed which could form the
organizational and scientific manpower nucleus for an expanded research and development program. The
costs of such a capability are not included in the foregoing estimates and
recommendations. The organizational
structure for this capability should
provide machinery for assuring an
interdisciplinary approach to weather
and climate modification—encompassing the physical, engineering, biological and social sciences.
One can not comment conclusively
on the required nature, organization
and financing of the new research and
development enterprise described
here. The need is clear; the question
is how. The President's Special Assistant for Science and Technology might
wish to initiate the appropriate feasibility studies as to the nature, precise
functions, and location of the new
enterprise.
ADMINISTRATION
Existing Statutory and
A11101HISIFaIlVe oirecoves
a. Coordination of Scientific Policy
Both the Federal Council on Science
and Technology and the National
Science Foundation have responsibilities with regard to scientific policy on
weather modification research and
operations. The Federal Council, under the Chairmanship of the Science
Advisor to the President, is given
general coordinating responsibility for
science policy within the executive
branch of the Government. This au130
thority is provided both by Reorganization Plan No. 2 of 1962 and Executive Order 10807 of March 13, 1959.
The Federal Council, under the provisions of Executive Order 10807, is
charged with the following responsibilities:
Sec. 2. Functions of Council (a) The
Council shall consider problems and
developments in the fields of science
and technology and related activities
affecting more than one Federal agency
or concerning the overall advancement
of the Nation's science and technology, and shall recommend policies and
other measures (1) to provide more
effective planning and administration
of Federal scientific and technological
programs, (2) to identify research
needs including areas of research requiring additional emphasis, (3) to
achieve more effective utilization of
the scientific and technological resources and facilities of Federal agencies, including the elimination of
unnecessary duplication, and (4) to
further international cooperation in
science and technology.
The Advisory Committee on
Weather Control recommended that
the National Science Foundation coordinate weather modification research.
Under the authority of PL 85-510 and
the legislative history thereof, the
Foundation was expected to take the
lead among the various Federal departments and agencies in the support
of weather modification research. The
Foundation complied by supporting
sponsored research which provided
the underpinnings for the more mission oriented programs of other agencies. The Foundation established and
has continued an annual Interagency
Conference on Weather Modification,
which has become a focus for government-wide program planning and coordination.
At about the same time that the
Federal Council for Science and Technology was established in 1958, the
National Science Foundation recognized the need for a formal interagency
coordinating mechanism in connection
with its newly assigned statutory responsibility in the field of weather
modification by establishing an Interdepartmental Committee on Weather
Modification. During the June 1959
meeting of the Federal Council there
was discussion concerning the establishment of a Committee to cover the
field of Atmospheric Sciences. The
President's Science Advisor and the
Director of the Science Foundation
agreed that the Foundation existing
131
Interdepartmental Committee on
Weather Modification could serve the
needs of both the Federal Council and
the Foundation. As a result, the Interdepartmental Committee on Weather
Modification was formally reconstituted as the Interdepartmental Committee for Atmospheric Sciences
(ICAS) and held its first meeting as
such on September 9, 1959.
Thus, general coordination on behalf of the President's Executive Office
with regard to research in this and
related fields is exercised by one of
the committees of the Federal Council
on Science and Technology—the Interdepartmental Committee for Atmospheric Sciences (ICAS). Within ICAS
is a panel on weather modification
research which is chaired by the Head
of the Section on Atmospheric Sciences of the Foundation.
b. Support of Research by Individual Agencies
Since 1940 the Federal Government
has assumed an increasingly important role in the financing and conduct
of scientific research and development
in this country. This has been especially true in the natural sciences and
engineering. In recent years, however,
the Foundation and other agencies
have become significant supporters of
research in the social, as well as the
natural sciences.
Research is supported not only to
accomplish agency missions—usually
as a forerunner to development—but
also to increase the broad body of
scientific and technical knowledge
which underlies the future advancement of the Nation's welfare, economic
growth, and security. This is particularly true of basic research conducted
primarily in academic institutions but
also in government, industrial, and
other laboratories focusing on fundamental problems in science.
The President's budget for FY 1966
contemplated an outlay of $14.5 billion for research and development of
which $4.9 billion was estimated for
research and of which $2 billion is for
basic research.
Executive Order 10521 issued in
March, 1954 and amended in March,
1959 provides that:
Sec. 4. As now or hereafter authorized or permitted by law, the Foundation shall be increasingly responsible
for providing support by the Federal
Government for general-purpose basic
research through contracts and grants.
The conduct and support by other
132
Federal agencies of basic research in
areas which are closely related to their
missions is recognized as important
and desirable, especially in response
to current national needs, and shall
continue.
In other words the Foundation is
charged with the support of basic research across the board and individual
agencies are authorized to conduct
and support such basic research as is
necessary to sustain their operational
missions.
tion Research Programs
Public Law 85-510 directs the Foun1.
c.
National Science Foundation
Conduct of Weather Modificadation "to initiate and support a program of study, research, and evaluation
in the field of weather modification,
giving particular attention to areas
that have experienced floods, drought,
hail, lightning, fog, tornadoes, hurricanes, or other weather phenomena,
and to report annually to the President
and the Congress thereon." The Foundation's responsibility is therefore not
only to support weather modification
research, but to present an overview
of the state of knowledge and effort
in weather modification. It also promotes the exchange of information
about the plans and programs of the
various Federal agencies and provides
for cooperation and coordination at
the working level through various
mechanisms, including the annual
Interagency Conference on Weather
Modification, where much of the current Federal interest in weather modification has been kindled.
Despite the broad statutory language cited above, the Foundation has
elected to confine its research activities to basic research, generally of
the type that the Foundation would or
could have supported anyway under
its general authority to support basic
research in the sciences. The Foundation selected as the first necessary task
the development of a sound scientific
basis for the art of weather modification. The stature of the Foundation
gave creditibility to a field which had
been plagued with a lack of technical
and scientific understanding. The
Foundation approached the leading
meteorologists and other scientists
with financial support to undertake
scientific investigations to open the
doors of knowledge.
The research-support program is
managed as an integral part of the
Foundation's over-all program of in133
vestigation in the atmospheric sciences. The dividing line between research in weather modification and
basic research in the atmospheric sciences is difficult to draw, especially
when so much more fundamental
knowledge is required to provide the
scientific basis for a successful national program for developing new
and improved weather modification
techniques.
Through grants with key university
groups and through the contract support of the National Center for Atmospheric Research (NCAR) the Foundation has given special emphasis to
studies on the development of models
to describe the natural processes
which produce the clouds, the weather,
and the general circulation of the atmosphere. Many problems confront
the designer of such a theoretical
model, among which are the inadequate observations of natural phenomena to establish the proper theoretical
approach. It is difficult to determine
how natural atmospheric phenomena
may be made accessible to human
intervention, and it is also difficult to
assess the results of such intervention.
The burden is therefore placed on the
theoretician to make sufficient progress in raising the level of physical
understanding to commit the proposed
model to theoretical analysis.
Foundation support for weather
modification research in 1965 totaled
$2.0 million for 28 projects. The Atmospheric Sciences Program of which
weather modification is a part has
grown from $2.9 million in FY 1959
to $23.2 million in FY 1965.
Under PL 85-510 research programs
conducted by the Foundation were
rather expected to include cooperative
programs with States. By implication
the Foundation was directed to engage in applied research and development as well as basic research with
regard to weather modification. Additionally, the Foundation was authorized to obtain by regulation or otherwise information it deems necessary
to its program of study, research and
evaluation in the field of weather
modification. The statute also directs
the Foundation to give particular attention to geographic areas which are
afflicted with recurring damage from
weather—flood, drought, hail, etc.
(2) Department of Commerce
The Weather Bureau, a part of the
Environmental Science Services Administration (ESSA), has initiated a
basic and applied research program in
134
the field of weather modification, holding that this type of activity is consistent with and necessary to the accomplishment of the basic mission of
the Weather Bureau—namely, the provision of increasingly accurate forecasts and warnings of weather and
flood conditions.
Experiments on tropical clouds and
hurricanes are conducted jointly with
the Navy under Project STORMFURY.
The clouds are studied in relation to
the hurricane system and as they operate during undisturbed weather conditions. The technique used to explore
the cloud mechanism has been silver
iodide seeding using pyrotechnic devices called Alectos; a broader experimental program is planned for the
future. The project is in the research
phase, and experimental operations
have been performed to probe the
mechanisms involved in convective
motions in cumulus clouds over the
ocean. Scientific experiments on the
large-scale atmosphere appear to be
necessary before the reduction of the
severe storm hazard by manmade control of convective phenomena can be
realized.
Development of theoretical models
is continuing which are capable of
reproducing and accounting for the
natural processes which produce the
weather and circulation of the atmosphere. Special attention is being given
to research dealing with the interactions at the ocean-atmosphere surface.
In a recent report to the President,
the Secretary of Commerce recommends an enlarged national program
of weather modification and states his
intention that the Environmental Science Services Administration (comprising the Weather Bureau, Coast and
Geodetic Survey and related agencies) take a leading role in such a
program.
(3) Department of Defense
The Department of Defense has consistently carried on an active program of weather modification research
as weather phenomena related to respective military missions of the three
services. These are described below.
(i) Air Force
The program of the Air Force in
cloud physics is centered around the
activities of the Air Force Cambridge
Research Laboratories at Hanscom
Field, and is directed towards a study
of the life cycle of clouds, utilizing
ground radar and highly instrumented,
135
cloud-physics aircraft. Observations
are made of the atmospheric electrical properties in the vicinity of the
cloud environment which are coupled
to the refractive index measurements
before, during, and after cloud penetration. The dynamics of clouds are
studied by both aircraft penetration
and by stereo ground-camera networks. This work is supplemented by
laboratory studies of the micro-physical properties of clouds. A cumulus
cloud observational program is carried
on in Florida during the summer
months to obtain information on cumulus growth and precipitation.
In an effort to establish a sound
scientific basis for the development of
fog forecasting and fog-modification
techniques, the Air Force has undertaken a comprehensive field research
program to characterize and understand the natural life cycle and variability of warm fog. The program has
been nicknamed Project CATFEET.
Cape Cod, Mass., was selected as the
site for this research, with Otis Air
Force Base being the main instrumented facility. The first data were
obtained at this site during July and
August of 1964. The formation, development, and dissipation of the fog
was documented by intensive measurements of the significant meteorological parameters utilizing a micrometeorological tower and a cloudphysics research facility on the base.
An 11-station mesometeorological network extending over the southwest or
upwind section of the Cape was also
placed in operation. A laser disdroineter, for measuring droplet size, is
among the new instruments which
were developed especially for this
program. More data from this program
was gathered during 1965 and are now
being reduced and analyzed.
(ii) Army
Research in weather modification
has been centered primarily around
the Army Electronics Research and
Development Laboratories in New
Jersey and their contractors. The objective of the Army research program
is to obtain a better understanding of
the physical concepts of rainmaking.
Activity has been centered in three
particular areas of effort; namely, the
basic studies of cloud physics mechanisms, the basic understanding of precipitation phenomena, and the basic
concepts of modification. On the
whole, work in cloud physics has been
concentrated upon convective cloud
136
systems. A program of thunderstorm
research was conducted during the
summer in the area of Flagstaff, Ariz.,
where basic cloud mechanisms were
studied which might provide possible
applications to the modification of
cumulus-cloud dynamics and nucleation. A small program has been carried out in the areas over the Great
Lakes, where a considerable amount
of snow is usually obtained. An effort
was made to learn more about the
temperature inside clouds by studying
the formation of ice crystals after
seeding with dry ice. Other studies
have included nuclei counts within
clouds, the collection of raindrop
spectra, comparison of raindrop size
at different wind speeds, and the coalescense of raindrops.
(iii) Navy
The efforts by the Navy in weather
modification are centered around two
phenomena: warm fog and trade winds
cumulus clouds. The principal laboratory and field work is carried out by
scientists attached to the Naval Research Laboratory. Work is in progress
along three general lines: (a) Development of aircraft instruments possessing fast response and accuracy to
measure the water content and clouddroplet size distribution in clouds.
Studies of the origin and nature of
cloud condensation nuclei and of the
role of nuclei in cloud and fog formation, stability, and precipitation, and
Exploration of the feasibility of
using tracer techniques to study cloud
motions and the interchange between
a cloud and its environment.
Work in weather modification being
performed at the Naval Ordnance Test
Station at China Lake during 1964 has
been in the field of development of
means for changing weather and cloud
conditions for tactical purposes. Responsibilities for planning and coordination of naval activities in the
environmental-control research area
has been assigned to the Navy Weather
Research Facility located at Norfolk,
Va. Included in the current program
already underway are the following:
(a) The use of the operations research approach to speed up the
eventual applications of environmental
control in naval operations. (b) Consideration of the applications of current and potential weather techniques
in the support of naval operations.
(c) Planning and coordination of the
Navy portion of the Project STORMFURY program.
137
(4) Department of Interior
Due to the interest by some members of Congress (principally from
western States) in an aggressive program of weather modification, the Bureau of Reclamation has been directed
through appropriation language to inaugurate a weather modification research program with emphasis on the
engineering aspects. The program was
started during FY 1962. It is directed
toward learning if it is possible to increase inflow into the Bureau's reservoir system.
The Department of the Interior's interest in weather modification is concerned with the atmospheric water
resources of the Nation and the possibility that weather modification will
supply additional precipitation and
runoff to the river basins which feed
the Bureau of Reclamation reservoirs.
Planning within the Bureau of Reclamation points to a possible 25-year
program. The Bureau program is
founded in part on the continuation
of a number of programs initially developed under Foundation sponsorship which have now matured to the
point where engineering research can
be established. Examples include continuation by the University of Nevada
of the artificial seeding of clouds by
the Humboldt River Basin and an increased effort at South Dakota School
of Mines and Technology.
To manage and coordinate the program an Office of Atmospheric Water
Resources was established in Denver,
Colorado. A small group of engineers,
meteorologists, and administrative
personnel have been assigned to staff
this new office. The program will be
conducted largely as a contract activity of the Bureau of Reclamation.
(5) Department of Agriculture
The continuation of Project SKYFIRE represents the primary effort of
the Forest Service in the area of
weather modification during FY 1964.
Project SKYFIRE is a research study
on the electrical nature of thunderstorms and the relationships of forest
fires resulting from cloud-to-ground
lightning charges. Attempts are being
made to modify thunderstorms in
ways that will decrease the number
and intensity of cloud-to-ground lightning. The project has two long-range
objectives: (a) To obtain a better understanding of the occurrence and
characteristics of lightning storms and
lightning fires in the northern Rocky
138
Mountain region; and (b) to investigate the possibility of preventing or
reducing the number of lightning fires
by applying techniques of weather
modification.
The Department plans to continue
the study of the relationship between
lightning discharge and forest-fire ignition. Points to be considered are the
characteristics of the lightning stroke
which produces ignition. In some
cases, lightning strokes may be prolonged by the bridging of several
thunderstorm cells which produces
more effective ignition than a shorterduration stroke of much higher peak
intensity. Investigation is also continuing on the effects of seeding upon
the electrification mechanism, and the
Department hopes that some information will be derived as to the mechanism whereby cloud seeding will affect the buildup of charge in the
thunderstorm.
Problems
a. Disparity Between Congressional Interest in Weather Modification and National Science Foundation
Policy
The legislative intent of PL 85-510
regarding the Foundation is fairly
clear; the Congress desired an aggressive research program covering both
research and development. The Foundation has felt until the last year or
two that the state of the art dictated
a more conservative approach. The resuit has been that the Foundation's
efforts have largely been in the award
of grants for research in atmospheric
sciences of a type that could have
been made under the basic authority
of the Foundation in the absence of
the Weather Modification Act (PL
85-510). It was also the hope of Congressional sponsors of PL 85-510 that
the Foundation would continually appraise and evaluate the research under
way in the U. S. and other countries
and would provide the Congress with
"readings" on the prospects of weather
modification. The Foundation has
largely refrained from this type of activity on the ground that research results have not been of a sufficiently
extensive nature that would sustain or
justify evaluative judgments.
b. Duplication in Research Activities and Coordinative Responsibilities
The intention of PL 85-510 was that
the Foundation would carry primary
responsibility within the Executive
139
Branch for weather modification research and would assume leadership
of the research activities of the other
Federal agencies in this field. For the
first few years, the Foundation assumed and held the initiative, with
respect to coordination as well as research. It was through the early leadership of the Foundation that a continuing and orderly interchange of
research plans, proposals and findings
among the interested Federal agencies
was provided. In subsequent years,
as a result of the creation of the Federal Council on Science and Technology with its coordinative responsibility for science policy across-the-board
and as a consequence of the Foundation policy decision to generally confine its activities to the support of
basic research on weather processes,
the coordinative role initially asserted
by the Foundation passed to the Executive Office of the President. Within
the past three years the situation regarding research activity has also
changed. Two other prominent civilian
agencies now "operate" in the weather
research field—the Weather Bureau
and the Bureau of Reclamation.
So long as weather modification activities are largely confined to the
basic research phase, this duplication
does not constitute a significant problem. Indeed, it is probably well that
there be mild competition among
agencies. In a field of science that is
both new and critical a diversity of
approach is much to be preferred to
a centering of responsibility, funds
and research direction in a single spot.
Certain aspects of weather modification activities have now reached the
applied research and operations phase,
with regulatory activity not far away.
An expanded fundamental research
program is now desirable and feasible,
some of which involves significant
logistics aspects.
some FaCIOPS AffeCling
ASSIgnment ot flesponsihility
Following are some of the considerations which need to be taken into
account by the National Science Foundation, other Federal agencies, the
President, and the Congress in fixing
responsibility for weather and climate
modification activities.
(1) There is need to bridge the
organizational gap between labora140
tory research and large scale field experiments; this gap can exist even in
the basic research aspects.
There is need for organizational arrangements for enough applied research to develop the field,
while preserving scientific objectivity
in the basic research effort. The economic, political and dramatic aspects
of weather and climate modification
operations must not be permitted to
crowd out the basic research.
There is need for biological
and social science research to go hand
in hand with the physical science and
engineering research in support of the
missions of all agencies, contractors
or grantees concerned with weather
modification.
There is need to preserve
diversity in the research effort, but
there is the need also to establish a
Federal organizational mechanism for
accomplishing what can not be done
through diverse research activities.
Responsibility should be
clearly assigned for the formulation of
arrangements for appropriate scientific cooperation with the governments
of other nations.
Adequate enforcement
power needs to be provided an administering agency so as to insure the
filing of information relative to all
weather modification field experiments and all commercial operations.
In the absence of compelling reasons otherwise, the agency assigned regulatory functions should
have a regional or field office establishment.
The conduct of research
and development in this field should
be kept insulated from activities involving the regulation of weather
modification operations, but at the
same time the two types of activity
should be sufficiently proximate organizationally to assure immediate access to data derived from the operations being regulated.
Loog-Range AlleroaNves
a. Continuation of the Status Quo
The case for this alternative is that
in a field as complex and uncertain as
weather and climate modification, the
best efforts of the four principal agencies now engaged in weather research
are needed—Defense Department,
ESSA—Weather Bureau, National Sci141
ence Foundation, and the Department
of the Interior. None of the existing
programs are in competition and all
of them are necessary at the present
stage of research and development.
There is an ultimate need for a
more specific assignment of responsibility for weather and climate modification activities in the Government.
Until the nature of the scientific feasibilities are further identified, however, the direction which such an assignment should take is not clear. For
example, if in the further developmental phases, activity by a very
large number of aircraft, over an indefinite period is required, this logistics essential might weigh heavily in
favor of assigning the operational mission to the Air Force. If, on the other
hand, for example, it becomes necessary to bring together large numbers
of university groups and commercial
operators into a combined research
and operational effort, the ESSAWeather Bureau or the Department of
Interior with their field establishments
might draw this assignment.
b. Assignment of Responsibility
for Weather and Climate Modification
to the Department of Commerce
The following factors tend to favor
such an assignment:
A close and inextricable
connection exists among weather prediction, weather research, weather
modification and operation. Intensified
data collection, dissemination, evaluation, storage and modeling activities
recommended as a key part of the
weather and climate research activity
are closely related to the weather prediction activities of the Weather Bureau. Understanding more about
weather and climate processes is indispensable both to modification and
to prediction activities.
The Weather Bureau has
the logistical capability for mounting
weather modification operations, including large scale field experiments.
The Weather Bureau is a
logical agency to represent the U. S.
Government in the intergovernmental
aspects of weather modification. The
Bureau has always served as the official United States link with the World
Meteorological Organization.
142
c. Assignment of Responsibility
for Weather and Climate Modification
to the Department of the interior
The following factors tend to favor
such an assignment:
The phase of weather modification now most nearly ready for
aggressive applied research, development, and actual operational activity
—the augmentation of precipitation;
—is vitally linked to the water management program of the Bureau of
Reclamation.
Weather modification activities including basic and applied research relate closely to those economic and political interests that are
concerned with the overall mission
and programs of the Interior Department. This would go far to assure
priority attention and adequate funding of the weather and climate modification program.
Weather modification activities are highly compatible with the
basic long range mission of the Interior Department—the conservation,
development and use of scarce natural resources.
The Department of Interior
has field offices throughout the nation.
d. Assignment of Responsibility
for Weather and Climate Modification
to the National Science Foundation
The following factors tend to favor
such an assignment:
Only in the Foundation
would the basic research aspects of
weather and climate modification be
reasonably secure from "crowding
out" by operational activities. Even if
the Foundation should also carry on
the essential developmental and operational activities, the agency's habits
and the dedication of its staff to the
promotion of basic research would
assure adequate support of the basic
scientific phases.
The Foundation already has
the unique capability for providing an
interdisciplinary approach to both the
research and developmental aspects
of the function, making sure that the
physical, biological, social science and
engineering facets are not neglected.
This capability exists through the
Foundation's authority to support
basic and applied research in the
fields related to weather modification.
The Foundation has had
seven and a half years of experience
in research leadership with regard to
weather modification. Other agencies
143
have become accustomed to looking
to the Foundation for initiative and
support for weather modification research.
e. Other Considerations
The assignment of responsibility
within the Federal Government for
weather modification would be little
more than a routine matter of internal
government coordination were it not
for the fact that the entire approach
to the scientific and practical problems of weather modification has
recently undergone a subtle yet profound change. Five years ago attention was rather vaguely focused on
the physics of clouds and the possible
consequences of cloud seeding. The
development of techniques for meteorological modeling, the feasibility
of computers 100 to 1,000 times faster
than those now available, and the
rapidly expanding capabilities for
global observations have escalated
the problem of weather and climate
modification into new dimensions of
scientific and technological opportunity.
The mode of research management
under which a national program has
been conducted in the past (with its
advantages and its shortcomings) may
be completely inadequate for the
character and the scale of the work
that will be required in the future.
In the event of dramatic scientific
progress, weather modification and
climate control could very well develop into a major priority program.
In this event, the program would need
a new governing statute and an upgrading in terms of organizational status, with the possible creation of a
new independent agency for the purpose.
The major alternatives in assigning
organizational responsibility for
weather and climate modification activities have been described. Before
considering possible changes in or
combinations of these possibilities it
would be well to enumerate some of
the factors tending to militate against
assignment to the agencies discussed,
and to consider the general problem
of coordination.
f. Disadvantages of Particular
Agencies
(1) The Reclamation Bureau is
limited in geographic jurisdiction to
the Western States. Significant amendment to its statutory authority would
have to be made were it to undertake
responsibility for weather and climate
144
modification. Also, only one aspect of
weather modification —precipitation
augmentation—is related to the overall mission of the Bureau. These limitations do not extend to the other
water, land, recreation, wildlife and
mineral functions of the parent Department—the Department of Interior.
The National Science Foundation lacks the logistical capabilities
for developmental and operational activities in the field, although these
could be acquired.
The Weather Bureau lacks
broad authority and experience in the
conduct and support through grant
and contract of basic scientific research, although its in-house capability in this regard has been improving
and extra-mural capability could be
acquired.
g. Coordination
Under no conceivable set of conditions could all concern with research
relating to weather and climate be
confined to a single agency. This leads
to obvious problems of coordination
and related problems of allocation of
resources of funds and manpower,
sharing and channeling of information, and scientific emphasis and direction.
The very close interrelationships
among basic research, applied research, development, operations, regulation, weather prediction, and the
missions of the various interested and
concerned agencies add to the difficulties. The coordination problem, of
course, tends to be roughly commensurate with the degree to which responsibility is centralized or dispersed
among the agencies.
Cooclusloos and
flecommeooatioos
The Commission has considered
carefully the problems attendant upon
the assignment of responsibility for
weather and climate modification activities within the Exeuctive Branch
of the Federal Government.
There are no easy solutions to these
questions. The Commission believes
the adoption of the following recommendations would significantly improve the effectiveness of the Nation's
efforts in this field, and would facilitate the achievement of the scientific
and other objecives specified elsewhere in this report.
145
a. Responsibility for Research,
Development, and Operations
The Commission recommends: (1)
the assignment of the mission of developing and testing techniques for
modifying weather and climate to a
single agency in the Executive Branch
of the Government—for example to
the Environmental Science Services
Administration of the Department of
Commerce or to a completely new
agency organized for the purpose; (2)
the continuance and expansion of research in the atmospheric sciences by
the National Science Foundation, including its program directed at providing a satisfactory scientific basis
for weather and climate modification
and the maintenance of the National
Center for Atmospheric Research as a
basic research facility for this purpose; and (3) the conduct or support,
pursuant to Executive Order 10521, of
such basic and applied research by
other Federal agencies as is required
for their varied missions as well as
the conduct of operational activities
necessary for the accomplishment of
such missions (e.g., precipitation augmentation for the reservoir system of
the Bureau of Reclamation; lightning
suppression by the U. S. Forest Service; military applications by the Department of Defense; etc.).
The degree of the Foundation's special attention to this field, including
the support of related research in
other affected disciplines, should be
reviewed from time to time in the light
of the progress of the overall national
program. The Foundation needs to
continue the vigorous support of basic
research in the atmospheric sciences
because fundamental knowledge so
derived is a necessary underpinning to
technological progress in weather and
climate modification.
The agency assigned the mission of
developing and testing techniques for
modifying weather and climate, as a
part of its overall mission, should
have major but not exclusive responsibility in collaboration with the State
Department for formulating and
implementing weather and climate
modification programs involving international collaboration with the governments of other nations. The government's activities in international
cooperation can be substantially assisted by the participation of the National Academy of Sciences.
146
b. Regulation
The Commission recommends that
responsibility for appropriate Federal
regulation of weather and climate
modification activities to aid the Federal Government's program of research
and development and to protect the
general public be kept separated from
research and development activities
while assuring prompt and full availability to such activities of data derived from the regulation of commercial and other operational activities.
Such a combination might be
achieved, for example, by assigning
the regulatory function to some part
of the Department of Commerce not
concerned with weather and climate
research and development.
Earlier in this report there has been
discussed the nature of minimum regulatory action which may be required
on the part of the national Government to assure the integrity of experiments conducted by Federal agencies or their grantees and contractors.
It should be pointed out in this connection that Federal agencies and
their contractors and grantees themselves will necessarily be subject to
some of the same types of regulation
that apply to commercial operations.
A Federal agency field experiment involving large-scale cloud seeding for
example, can cause the same interference with other scheduled experiments as can cloud seeding conducted
by a commercial operator.
Consequently, Federal agencies will
need to be subject to many of the
rules and regulations issued by the
type of regulatory unit recommended
above. Insofar as the regulation involves requirements of notice of experiments, licensing of activities and
the like, there would seem to be reason why all Federal agencies should
be subject thereto. The regulating
agency should also have the power to
resolve minor conflicts between agencies, such as the precise timing of
particular experiments. Any major
disagreements would involve policy
and administrative coordination as
discussed below.
c. Inter-Agency Coordination of
Policies and Program Activities
The Commission recommends that
there be established within the Office
of Science and Technology (OST) a
special mechanism for the coordination of weather and climate modifica147
tion programs and for recommending
such steps as may be appropriate for
effecting a unity of governmental policy in this field.
If the general mission of developing
the technology for climate modification is assigned to a single agency,
present overlap and lack of concerted
effort among the various agencies will
be remedied to a considerable extent.
Due to the great importance of the
field, however, and because of the
necessity of maintaining an interdisciplinary and international approach
to weather activities, it is believed
that continuing attention must be
forthcoming from the Executive Office
of the President. Consequently, some
mechanism concerned solely with
weather and climate modification,
with emphasis on the development
and operational side, needs to be established within the OST. The OST's
concern should embrace funding, basic
research, applied research, development, testing and evaluation. Such a
mechanism could take over from ICAS
the weather and climate modification
components. ICAS could continue to
be concerned with atmospheric research.
d. An Advisory Committee
The Commission also recommends
the utilization of the National Academy of Science and the National
Academy of Engineering for continuing review and advice regarding the
national program of weather and climate modification.
Both the President's Science Advisory Committee and the Congress
need to be able to obtain scientific and
public policy advice from a group of
knowledgeable people from outside
the Government. This need could perhaps be met by the appointment of a
standing committee in the National
Academy of Sciences in cooperation
with the National Academy of Engineering. Such a committee includes
persons with experience in the physical sciences, engineering, the biological sciences and the social sciences.
148
APPENDIX
Bibliography of reports remaining to
be published of research and studies
performed under National Science
Foundation grants and contracts in
support of the work of the Special
Commission on Weather Modification.
Biological Aspects of Weather
Modification, Ad Hoc Weather Working Group, to be published in the
March, 1966 issue of the Bulletin of
the Ecological Society of America.
Human Dimensions of Weather
Modification, W. R. Derrick Sewell
(Editor), to be published in the University of Chicago Department of
Geography Research Papers in February, 1966.
Weather Modification: Law, Controls, Operations, H. J. Taubenfeld,
et al, to be published by the National
Science Foundation in January, 1966
(NSF-66-7).
International Relations and
Weather Modification, Leonard E.
Schwartz, to be published by author.
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