NSF 66-3

WEATHER AN MODIFICATION Repori 01 ine SPECIAL COMMISSION ON MOIJIFICATION

NATIONAL SCIENCE FOUNDATION

WEAMER AND CLIMATE MODIFICATION Repori 01 me SPECIAL COMMISSION ON WEATHER MODIRCATION

NATIONAL SCIENCE FOUNDATION

LETTER OF The Honorable Leland J. Haworth Much of the background work for the Director treatment of the other aspects of the National Science Foundation problem was carried out under RANSMITTAL Washington, D. C. National Science Foundation grants or contracts, reports of which research Dear Dr. Haworth: and study are to be published as It is an honor to transmit herewith stated in the Appendix. to the National Science Foundation The Commission held eleven the report of the Special Commission meetings supplemented by many days on , authorized of study, research, writing and by the National Science Board at its conferences. The Commission report meeting on October 17-18, 1963, in has been prepared by and its content accordance with Sections 3(a)(7) and is concurred in by all the members 9 of the National Science Foundation of the Commission. Act of 1950, as amended, and The Commission was assisted appointed by you on June 16, 1964. throughout its deliberations by an The Commission was requested to Executive Secretary. Dr. Edward P. examine the physical, biological, legal, Todd served in this capacity during social, and political aspects of the field the early months. Mr. Jack C. and make recommendations concern­ Oppenheimer succeeded Dr. Todd ing future policies and programs. and has done an outstanding job of The physical science aspects have assisting the Commission. been studied primarily through Respectfully submitted, cooperative liaison with the National A. R. Chamberlain, Chairman Academy of Sciences' Panel on Vice President Weather and Climate Modification. State University

December 20, 1965

I" The Commission was established SPECIAL pursuant to Section 3(a)(7) and 9 of Department of Economics the National Science Foundation Act University of Minnesota of 1950, as amended. Thomas F. Malone, COMMISSION The names and affiliations of the Second Vice President Research Department Commission members are: Travelers Insurance Company ON A. R. Chamberlain, Chairman Arthur W. Murphy Vice President, Colorado State University Columbia University School of Law WEATHER Sumner T. Pike John Bardeen, Vice Chairman Lubec, Maine Departments of Physics and Electrical MODIFICATION Engineering William S. von Arx University of Illinois Massachusetts Institute of Technology and Woods Hole Oceanographic William C. Colman, Institution Executive Director Gilbert F. White Advisory Commission on Department of Geography Intergovernmental Relations University of Chicago John C. Dreier Karl M. Wilbur School of Advanced International Studies Department of Zoology The Johns Hopkins University Duke University

iv LETTER OF TRANSMITTAL ...... �iii SPECIAL COMMISSION ON WEATHER MODIFICATION�iv HISTORICAL BACKGROUND ...... 1 SUMMARY...... 7 Introduction�...... 7 ONTENT$ 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 -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 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 WEATHER MODIFICATION AND INTERNATIONAL RELA- TIONS...... 113 International Programs Related to Weather Modifica- 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 Twenty years ago not new to our era or to our country. HISTORICAL Company scientists Many traditional societies, including and modified the American Indians, have practiced by "seeding" them with dry pel­ some type of religious or ritualistic BACKOHOUND lets. Not long afterward Bernard Von­ . The ceremonials and rit­ negut, a co-worker, demonstrated that uals have varied from dousing holy a smoke of iodide crystals men with water to burying children would accomplish the same result. up to their necks in the ground in the This was the beginning of the modern hope that the gods would be sympa­ American history of weather and cli­ thetic and drop tears from the heav ­ mate modification through ens. These ceremonies are not only to seeding. induce some form of desirable weather These American scientists on No­ but also to reinforce the tribal reli­ vember 13, 1946, had verified experi­ gious beliefs and opinions which mentally the theory advanced in 1933 maintain social unity. by the Swedish meteorologist, Tor Through ancient and modern times Bergeron, and the German physicist, many methods have been proposed Walter Findeisen, that clouds would and attempted to induce or to aid precipitate if they contained the right rainfall. Two U. S. Government pat­ mixture of ice crystals and super­ ents on methods of rainmaking were cooled water drops. The Bergeron- issued before the turn of the 20th Findeisen theory was antedated by century based, respectively, upon the the work of the Dutch scientist, Au­ production of by ex­ gust Veraart. The enthusiastic reports pending "liquified carbonic acid gas" by Veraart of his 1930 experiments and upon concussion by the detona­ with and supercooled water-ice tion of explosives. Interestingly in Holland were not well received by enough the long since expired patent, the Dutch scientific community, and based on the production of carbon thus were given no serious considera­ dioxide in the form of dry ice, antici­ tion elsewhere. pated the cloud seeders of today. The Weather and climate modification, pioneering field and laboratory work or "rainmaking" (the more popular of meteorologists in the War and Navy and also more restricted concept), is Departments on the popular notion

1 that rainfall could be caused by the Whether or not the multi-million detonation of explosives was sup­ dollar commercial rainmaking activi­ ported by Federal Government funds. ties of the late 1940's and early 1950's Even social, political and legal con­ grew out of the obvious interest of the flicts over weather and climate modi­ Federal Government in weather and fication are not new. In 1916 San climate modification research or the Diego's employment of a rainmaker, coincidental severe conditions resulting in claims of loss of life and in some parts of the nation, relatively property damage of a million dollars, vast operations became a fact of life. anticipated by half a century the liti­ It was disclosed between 1951 and gation and State and local legislative 1953 in the Congressional Hearings action of today. leading up to the establishment of the The 1946 demonstration that clouds Advisory Committee on Weather Con­ might be modified and produced trol that during the height of cloud by scientific methods arose out of the seeding activities $3 to $5 million a World War II investigations of year was being spent by water users, particles by Langmuir and Schaefer. particularly in the West, for commer­ The military possibilities of this dis­ cial , and that about covery led the armed services to sup­ 10% of the land area of the United port a broad theoretical, laboratory States had become the target of cloud and field program in cloud modifica­ seeding attempts. tion from 1947 to 1952, known as The weather modification events of Project Cirrus. Civilian and military the late 40's and early 50's in the implications were investigated by the encouraged cloud seed­ Project of the U. S. ing programs in , France and Weather Bureau, Air Force and Na­ South Africa to increase precipitation tional Advisory Committee for Aero­ and renewed the scientific interest in nautics from 1948 to 1951. The mili­ suppression that had been prac­ tary services followed the termination ticed in Alpine Europe since the mid of Project Cirrus in 1952 with a De­ 30's. The dozen nations experimenting partment of Defense 5 year Artificial with cloud seeding during the late Cloud Nucleation Project. 1940's more than doubled by 1951 to

2 about 30 countries representing every The development of weather continent. modification must rest on a foun­ Meanwhile, the drought that held dation of fundamental knowledge sway in many parts of the country, that can be obtained only through the claims of some of the rainmakers scientific research into all the phys­ and the criticism from portions of the ical and chemical processes in the scientific community led the Congress . The Committee recom­ to create an Advisory Committee on mends the following: Weather Control to study and evalu­ That encouragement be ate public and private experiments in given for the widest possible weather modification. In its final re­ competent research in meteorol ­ port in 1957 the Advisory Committee ogy and related fields. Such re­ on Weather Control found, among search should be undertaken by other things, on the basis of statistical Government agencies, universi ­ evaluations, that cloud seeding in the ties, industries, and other organi­ mountainous areas of western United zations. States of occurring during the That the Government spon­ cooler and moist and months produced an average increase sor meteorological research more vigorously than at present. Ade­ in precipitation of 10 to 15 percent from seeded storms with a satisfac­ quate support is particularly tory degree of probability that the in­ needed to maintain continuity crease was not the result of natural and reasonable stability for long- variations in the amount of precipita­ term projects. tion. On the basis of its physical eval­ That the administration of uations, the Committee found, among Government-sponsored research other things, that seeding from the provide freedom and latitude for ground with generators choosing methods and goals. Em­ is a valid technique for seeding clouds. phasis should be put on sponsor­ As a consequence of these findings ing talented men as well as their and their related scientific and tech­ specific projects. nical studies the Advisory Committee That an agency be desig­ on Weather Control recommended: nated to promote and support re-

3 search in the needed fields, and On July 11, 1958, the President ap­ to coordinate research projects. proved PL 85-510 which, in pertinent It should also constitute a cen­ part, authorized and directed the Na­ tral point for the assembly, eval ­ tional Science Foundation to: uation, and dissemination of in­ • . . initiate and support a pro formation. This agency should be gram of study, research, and evalu­ the National Science Foundation. ation in the field of weather modi­ (5) That whenever a research fication, giving particular attention project has the endorsement of to areas that have experienced the National Science Foundation floods, drought, hail, , fog, and requires facilities to achieve tornadoes, hurricanes, or other its purpose, the agency having weather phenomena, and to report jurisdiction over such facilities annually to the President and the should provide them. Congress thereon. The above recommendations of the consult with meteorologists Advisory Committee on Weather Con­ and scientists in private life and with trol together with the 1957 report of agencies of Government interested the American Meteorological Society in, or affected by experimental re­ and the 1958 third report of the Com­ search in the field of weather con­ mittee on of the National trol. Academy of Sciences emphasized the • . . carry out the purposes . need for: fundamental knowledge; whether conducted by the Founda­ research; experimentation; education tion or by other Government agen­ and training in meteorology and re­ cies or departments, . . . through lated fields; promotion, support, co­ contracts with, or grants to, private ordination, evaluation and informa­ or public institutions or agencies, tion assembly and dissemination by including but not limited to coop­ the National Science Foundation; and erative programs with any State increased Federal support to universi­ through such instrumentalities as ties for basic research in the atmos­ may be designated by the governor pheric sciences. of such State.

4 Thus, for the last 7'/2 years the programs of weather modification re­ Foundation has been providing major search and development is about 7.2 support for the Federal Government's million dollars. During the year end­ weather modification program and ing June 30, 1965, there were 59 cloud also has been a focus for Govern- seeding projects by 15 commercial ment-wide program planning and operators concerning operations in 26 coordination through various mecha­ different states. At present there are nisms, including its annual Interagency research activities reported from 15 Conference on Weather Modification. foreign nations. During this same period, the Depart­ In November 1963, in response to ments of Agriculture, Commerce, increased concern over the potentiali­ Defense, and Interior have either ini­ ties for man-made changes of weather tiated or continued mission-oriented and climate and the interest in under­ programs of research and develop­ taking large scale weather modifica­ ment in weather and climate modifi­ tion activities, the Committee on At­ cation. These programs have been de­ mospheric Sciences of the National voted to such matters as research on Academy of Sciences (NAS) appointed the suppression of lightning-induced a Panel on Weather and Climate Mod­ forest fires by the U. S. Forest service; ification "to undertake a deliberate observation, analysis and experimen­ and thoughtful review of the present tal seeding of severe storms and hur­ status and activities in this field, and ricanes by the U. S. Weather Bureau; of its potential and limitations for the cloud physics research, experimental future." On June 16, 1964, the Direc­ seeding of clouds and dispersal of tor of the National Science Founda­ clouds and fog by the military depart­ tion announced the appointment of ments; and research on reduction of the Special Commission on Weather water evaporation through use of Modification, as previously authorized chemical films and increase of water by the National Science Board at its supplies through research and experi­ 89th Meeting on October 17-18, 1963. mental seeding by the U. S. Depart­ The Commission was assigned to: (1) ment of the Interior. fulfill the need of the National Science The FY 1966 total annual spending Foundation for a review of the state for all the various Federal agency of knowledge on weather and climate

5 modification, make recommendations sion. The physical, biological, statisti­ concerning future policies and pro­ cal, social, international, legal and grams and examine the adequacy of legislative, and administration and the Foundation's program; and (2) funding aspects have been studied by respond to the request of the Inter­ these sub-groups. The physical sci­ departmental Committee for Atmos­ ence aspects have been studied pri­ pheric Sciences of the Federal Coun­ marily through cooperative and con­ cil for Science and Technology of tinuing consultation and liaison with August 19, 1963 to prepare an analy­ the National Academy of Sciences' sis of the modification and control of Panel on Weather and Climate Modi­ the weather for useful purposes other fication. Much of the background than military. The Commission's as­ work for the treatment of the various signment included consideration of aspects of the problem was carried not only the scientific aspects but also out under National Science Founda­ the legal, social and political prob­ tion grants or contracts. Reports of lems in the field. these research and study activities In view of the broad categories of are to be published as stated in the questions directed to the Commission Appendix. The National Academy of by the National Science Foundation, Sciences has just completed its final the Commission activated seven sub­ report, entitled Weather and Climate groups, each of which was headed by Modification—Problems and Pros­ one or more members of the Commis- pects, Vols. I and II.

6 awareness of the changes that are occurring in his environment and also SUMMARY INTRODUCTION hopefully some means for deliberate Man is becoming so numerous and modification of these trends. An ap­ his influences on his environment so praisal of the prospects for deliberate profound that he cannot consider him­ weather and climate modification' can self free to heedlessly or improvi­ be directed toward the ultimate goal dently exploit the air, water, land, and of bringing use of the environment growing things of this earth. He no into closer harmony with its capaci­ longer lives under the constant threat ties and with the purposes of man- of a wilderness but, instead, is chang­ whether this be for food production, ing his environment and, therefore, relief from floods, assuring the con­ must plan for its conservation and tinuance of biologic species, stopping development. pollution, or for purely aesthetic rea­ With advances in his civilization sons. man has learned how to increase the The National Science Foundation fruit of the to in­ Special Commission on Weather Modi­ sure a livelihood. The main problems fication was asked to consider one which now threaten his future are: aspect of the problem of environ­ large-scale, catastrophic war­ mental conservation and utilization. fare; With the physical possibility of modi­ providing sustenance for a rap­ fying the weather and climate already idly increasing population; partly demonstrated, it is important to inquire: How by artificially inducing waste disposal and environ­ deliberate changes in the environment mental change accompanying may man act to control or develop the discharge of matter into the atmosphere, open waters, and 'Throughout this report the term "weather subterranean spaces. and climate modification" is taken to mean artificially produced changes in the compo­ Recognizing these circumstances of sition, motion, or dynamics of the atmos­ human activity, it is fortunate that phere, whether or not such changes may be predictable, their production deliberate or growing knowledge of the natural in advertent, or their duration transient or world has given him an increasing permanent.

7 changes in the atmosphere considered not only artificially influencing the to be desirable by society? With this atmosphere but by controlling inad­ question in mind, the Commission has vertent changes. For example, smog concerned itself with the physical, bio­ is the result of deliberate pollution logical, social, engineering and legal which causes inadvertent modification aspects of weather and climate modi­ of urban weather and climate. A num­ fication. ber of questions are involved: Weather and climate modification If deliberate modification of the is becoming a reality. The daily activi­ atmospheric environment is already ties of man influence the atmosphere a growing physical possibility, what in a number of ways and his ability are the scientific prospects for the to induce deliberate changes in meas­ future? urable magnitude by artificial means What may be the biological con­ is progressing. The scale of known sequences of weather and climate operational ability for deliberate rou­ modification activities? tine weather modification is presently What might be the social, human the dissipation of supercooled fog and and economic benefits to man? stratus over an area approximately the size of an airport, for a short period Are there legal, political and of time. On a larger scale, the inad­ legislative issues to be resolved? vertent modification of the weather How should the plans of the and climate by such influences as the United States in weather and climate products of urban development, sur­ modification be communicated to and face modification for agriculture and coordinated with other nations? silviculture, compositional changes What are the organizational and through the combustion of fossil fuels funding needs for a national program and other exhausts are becoming of in weather and climate modification? sufficient consequence to affect the These questions are explored in weather and of large areas some detail in the body of the report. and ultimately the entire planet. Summarized here are some of the Com­ Deliberate modification of weather mission's findings and conclusions and climate may be accomplished by relevant to these questions.

8 experimentation but the results, so far, Scieniffic Prospects are inconclusive. Changing the course or intensity Several cubic miles of super­ of extratropical and altering cooled cloud droplets can be trans­ climate over large areas remain as formed into ice crystals by seeding problems for the future. No serious with dry ice or silver iodide. Super­ attempt has yet been made to control cooled fog on the ground can be dissi­ tornadoes. pated. No practical approach to the Inadvertent changes in climate as dissipation of warm fog is at hand. a consequence of human activity (e.g., While the evidence is still some­ urbanization, , increase of what ambiguous, there is support for atmospheric carbon dioxide by burn­ the view that precipitation from some ing fossil fuels) are amenable to analy­ types of clouds can be increased by sis and deserve early attention. the order of ten percent by seeding. If the results are confirmed by further With respect to the scientific pros­ studies they would have great signifi­ pects for the future, the Commission cance. The question of corresponding finds that attractive opportunities exist. decreases of precipitation outside the Advanced experimental techniques target area is unresolved. and application of sophisticated con­ cepts in statistical design promise to Results from attempts to sup­ reduce the present uncertainty in the press hail in the United States are as interpretation of field experiments. yet inconclusive but more promising The scientific exploration of weather results in other countries are leading and climate modification is passing to the establishment in this country from the speculative phase to the of a program that should provide a rational phase. Within reach are more definitive answer. mathematical and laboratory modeling Experiments in lightning sup­ techniques that permit the simulation pression are beginning to show some of atmospheric processes. By these promise. means it should become possible to Modification of hurricanes has assess in advance the probable con­ reached the stage of preliminary field sequences of deliberate intervention.

9 An expanded program of basic and desirable, unanticipated and irrevers­ applied research is needed to take ible ecological changes. advantage of these scientific oppor­ tunities. special impucanons

Biological Consequences Weather and climate are among the major determinants of economic and Great uncertainty has been encoun­ social activity. Any change in pre­ tered regarding the biological conse­ cipitation, , and wind- quences of weather and climate modi­ whether deliberate or inadvertent—is fication. Augmentation of rainfall over likely to have a significant effect upon cultivated areas could partially allevi­ society. Although a number of tech­ ate the increasing problem of food niques are available for the study of production. However, there is an ac­ the economic and social impact of companying possibility that instabili­ weather modification, relatively little ties might result in the balances of has been done. Much remains to be biological communities. Such imbal­ learned of the manner in which man ances can be expected in the diseases responds to the normal variability in and pests of man's domesticated plants weather conditions. Relatively little is and animals. In small areas of natural known of the processes of decision- communities it is possible that some making in human activities in relation wild species may be severely stressed. to present day weather prediction. The timing of the atmospheric inter­ Economic and social analysis of these vention relative to the reproductive relationships is urgently required as cycle of the various species in the an aid in developing and applying community may be of more impor­ techniques of weather and climate tance than the magnitude of the inter­ modificiation. If the developing tech­ vention. Both field and simulation niques of weather and climate modi­ studies of these biological relation­ fication are to be used intelligently, ships are needed before, during and the human consequences of deliberate after sustained operational programs. or inadvertent intervention need to be These studies should help avoid un- anticipated before they are upon us.

10 Mal ASPeCtS Oruaouzation aM filMs Weather and climate modification The national program should involve poses legal questions as to the exist­ basic research, technology, operations ence of "property" interests in weather and regulation. There needs to be and the responsibilities of weather assigned to a single existing govern­ modifiers for damage to others, as well ment agency, or to a completely new as problems of regulation. It is too agency, the responsibility for develop­ early to make specific suggestions as ing the technology of weather and to the law which should govern "prop­ climate modification. The National erty" in weather, or the liabilities of Science Foundation should continue weather modifiers. However, recom­ and expand its support of research mendations are made as to needed in the atmospheric sciences, including regulation and indemnification of those its program directed at providing a working on government supported satisfactory scientific basis for weather programs. and climate modification. Other gov­ ernmental agencies should undertake such research and operational activi­ InIernallonal Reiallons ties in weather and climate modifica­ tion as their missions may require. The Commission finds far-ranging Federal financial support for re­ international implications in weather search and development activity in and climate modification. By its very weather and climate modification nature weather transcends national should be increased several fold over boundaries. An attractive opportunity present levels. exists to anticipate the effect of tech­ nological development in weather and climate modification upon interna­ SCIENTIRC POSSIBILITIES tional relations. Specific steps are recommended to foster international In pursuing means to modify weather cooperation in research and in the and climate man assumes the charac­ peaceful use of any physical capability ter of a force of nature. That state is that may evolve. not at all novel in that man by mad-

11 vertent acts has already modified some on a suitably broad foundation of in­ aspects of weather and climate through formed scientific, economic, legal and urban development, surface changes other opinion, with a clear appraisal for agriculture, forest culture and especially of the biological and eco­ flood control, and altered the compo­ logical risks involved. sition and thus the radiation balance There are four needs to be met in of the atmosphere through the com­ weather and climate modification: bustion of fossil fuels. Deliberate To assess and understand natural alteration of the atmospheric regimen is, however, a new concept. Thus far climatic change. the brightest hope for deliberate inter­ To assess and understand the vention lies in the possibility of alter­ inadvertent changes in weather and ing precipitation rates and dissipating climate that the technological evolu­ supercooled fog by silver iodide or dry tion of man has produced; ice seeding. This has caused the pros­ To improve man's ability to pre­ pect of weather and climate modifica­ dict the behavior of the atmosphere tion to be viewed mainly in the light so that he may arrange his affairs with of these techniques and their attend­ a minimum of danger or surprise; and ant geographic scales. To devise a variety of techniques If it is granted that the possibility for deliberate intervention in the of successful use of seeding procedures course of atmospheric (or other) proc­ is a real one, it must also be recog­ esses which will alter weather and nized that it is in the character of climate in the interest of mankind. modern man that he will press on to Why attention to the field is timely develop larger scale measures; some is well explained in the Introduction of which are already in the conceptual to Vol. I of the Report of the Panel on stages of . For this reason, Weather and Climate Modification of planning for research in weather and the National Academy of Sciences.' climate modification must be broad enough at its very outset to accommo­ 1 Weather and Climate Modification- date future progress toward large scale Problems and Prospects, Vols. I and II, Na­ tional Academy of Sciences-National Re­ or manifold activities. Moreover, judg­ search Council, 1966 (NAS-NRC 1350). Vol­ ment of sound action must be based ume II contains an extensive bibliography.

12 One might ask why so detailed a unproductive because of the sheer survey of the status and outlook of mathematical complexity of the sys­ atmospheric modification as we have tems of equations constituting the made should be undertaken at this models. The advent of high-speed time. During approximately the past automatic computers has, within the decade, subtle but significant shifts past decade or so, radically altered have occurred in long-term prospects this picture. Computing speeds and for weather and climate modification; storage capacity have risen by many in many fundamental respects, an orders of magnitude, and a growing earlier era of speculation had grad­ body of investigators in the atmos­ ually been superseded by the present pheric sciences has seized this power­ period in which rational and syste­ ful new tool to use it in analyzing matic exploration of modification po­ critical aspects of the physics of our tentialities has become possible. Sev­ atmosphere. The important practical eral changes stand out as factors goal of improved numerical weather causing this shift: prediction became a stimulus that has Formulation of increasingly com­ recently led many workers to con­ plete and elaborate theories of atmos­ duct increasingly elaborate computer pheric processes has advanced to a studies in the broad area of numerical state in which moderately realistic experimentation. Today, numerical mathematical models can be con­ simulation, albeit impressively com­ structed for a variety of atmospheric plex and varied in scope, is almost systems ranging in scale from micro- certainly only a primitive first step meteorological to global. Admittedly toward future levels of understanding crude and rudimentary in many in­ of the subtle and highly interdepend­ stances, such models constitute a ent workings of our atmosphere; but necessary first step in reducing the it is a beginning with foreseeably pro­ degree of empiricism that has charac­ found implications for weather modi­ terized most past speculations con­ fication. This development alone is cerning atmospheric modification. significant enough to justify a new and Prior to about 1950, such mathe­ deeper examination of modification matical models were for the most part prospects.

13 (3) Man's ability to measure and to Much of the present effort in weather observe the atmosphere with its myriad modification stems from the sugges­ parameters has been growing steadily. tion in 1946 of Langmuir and Schaefer Two decades of improvement in use that precipitation could be enhanced of aircraft as measurement platforms, by introduction of ice, or ice-like two decades of elaboration of radar- nuclei, into clouds. The basis for the of meteorological techniques, and soon suggestion is that condensation a full decade of experience with the water droplets into particles large enough to fall may occur by growth incomparable synoptic observing capa­ of ice crystals in supercooled parts of bilities of the meteorological satellite, the cloud. Water droplets may be combine with many other advances supercooled well below the in instrumentation and observation point unless freezing nuclei are pres­ systems to permit almost entirely new ent. If clouds lack a sufficient number dimensions in man's ability to keep of natural nuclei, precipitation could, track of the rapid changes that are so according to the theory, be enhanced characteristic of weather. Clearly, still by introduction of artificial nuclei into further improvements may be expected the appropriate parts of the cloud. In in the future, but one senses that subsequent years the many experi­ already we have available the meas­ ments done in this country and abroad urement skills requisite to monitoring to test the theory have led to inclusive adequately many of these atmospheric and controversial results. It has only systems we seek to modify. been during the past year, largely as a result of a thorough analysis of The three considerations discussed available data by the NAS Panel on above are of sufficient basic impor­ Weather and Climate Modification, tance to prospects for present and that statistical evidence, although still future weather modification that, even somewhat ambiguous, appears to show without the particular stimulus of cur­ that precipitation can be modestly rent advances in cloud modification enhanced locally by seeding. per Se, it would be most timely to Most of the experiments on which undertake a survey of the field of this conclusion is based are of an atmospheric modification. empirical nature. Typically nuclei are

14 introduced by ground-based silver undertaken which provide continuity iodide generators. Rainfall is meas­ over a period of 5 to 10 years on a ured in a target area extending per­ sufficient scale to permit geographic haps 30 to 50 miles downwind and comparisons and differentiation, as also in a control area upwind from well as stratification according to the the generators. By comparing the ob­ type of seeding agent, mode of injec­ served rainfall during the seeding tion, cloud type, etc. Provision should operations in the two areas with aver­ be made for the inclusion of relevant ages over past years, one can estimate precipitation data in addition to other the increase, if any, caused by seeding. relevant physical variables. This pro­ In some cases the seeding is done on gram should be designed and evalu­ a randomized basis and a comparison ated in close association with statis­ is made between seeded and unseeded ticians with extensive experience in days and areas. Because of the wide experimental design. variability of cloud systems, a great Another approach is through basic deal of data is required to obtain sta­ research on cloud physics. These tistically significant results and also to studies have shown that cloud sys­ ascertain under what conditions and tems are extremely complex and that what geographical locations seeding precipitation can probably occur in a may be effective. The possibility of number of ways. There is only a rudi­ some sort of systematic error or bias mentary knowledge of how the arti­ must be eliminated by statistical ficially induced nuclei enter the clouds design. and how precipitation is actually There is need for more empirical affected. Thus, there is a wide gap studies carefully designed to deter­ between the basic research studies mine how effective seeding is in in­ and cloud physics and an understand­ creasing rainfall or in suppressing hail ing of the empirical results of seeding. and lightning in various situations. In order to optimize seeding proce­ These experiments should be designed dures and to better assess their inher­ to give reliable and statistically sig­ ent limitations, much more must be nificant data. learned about the actual physical Toward this end a program of mechanisms involved. This requires planned field experiments should be more elaborate and expensive field

15 experiments in which a number of global scale for general circulation and variables are measured in addition to on a limited scale for local storms. over-all precipitation, or, in the case A broad research program of this sort of hail studies, the amount and nature is required and can be justified for aid of the hail. in long-range forecasting. Its impor­ A number of suggestions have been tance for making possible predictions made of possible methods to produce of consequences of deliberate and changes in the climate extending over inadvertent modifications of climate large areas. It is known that rather gives it added justification. abrupt changes in climate have oc­ Computer simulation and other curred in the historical past, but there studies should include a search for is as yet little understanding of the triggering mechanisms and means for factors which brought them about. It suppressing violent but marginally sus­ is possible that changes in climate tained extremes in weather. Further may also be produced inadvertently development of laboratory and com­ by activities of man. To assess the puter simulation should also yield probable consequences of both delib­ insights crucial to the design of field erate and inadvertent changes requires experiments, to systematic efforts to much better knowledge than is now modify weather and to long-range available of the general circulation of international planning of non-atmos­ the atmosphere and oceans, sources pheric methods of weather and cli­ and sinks of heat, and energy inter­ mate modification. changes at the surface of the earth. It is assumed that the mission-ori­ To acquire such knowledge will re­ ented programs already underway, quire many years of basic research. such as that of the Department of Man is now learning how to simulate Interior to attempt to increase precipi­ the atmosphere numerically with use tation over its Reclamation project of large digital computers and by use watershed areas and those of the De­ of laboratory models. It has been esti­ partments of Agriculture, Commerce mated that computers two orders of and Defense will be continued in both magnitude faster than those now in their scientific engineering and opera­ use will be required for adequate tional phases. These present experi­ simulation of the atmosphere on a ments should be continued. But, it is

16 essential that there be an increase of ternational study of all consequences. effort, either by agencies of govern­ But, the increasing levels of energy ment or by academic and other groups available to man are even now so to insure that the biological, legal, great that such proposals may be social and statistical aspects of the entertained. experiments are given sufficient atten­ To carry out the necessary labora­ ti on. Present mission-oriented field tory, field and theoretical research for experiments are examples of work a full understanding of atmospheric undertaken despite the fact that there and non-atmospheric weather and cli­ has been insufficient fundamental re­ mate modification and inadvertent search. If large-scale field seeding changes in weather, will require the activities are properly designed and efforts of people well qualified in dis­ controlled and can be supported by ciplines such as applied physics, engi­ adequate ecological investigations, neering, chemistry, statistics and mete­ with monitoring and associated funda­ orology, as well as biology, geology, mental research, there is no question oceanography, mathematics and hy­ that such experiments will yield knowl­ drology. edge benefiting weather modification In the view of the Commission, research while the public policy objec­ some of the greatest future needs of tive of attempting to increase precipi­ the physical sciences and engineering tation over the watersheds is being in weather and climate modification pursued. research and development are: en­ One can conceive of non-atmos­ hancement of the support of funda­ pheric possibilities for deliberate mental research looking to creative ideas; much greater logistics capability weather and climate modification for supporting large-scale experiments which could lead to major changes in whether over sea or land; careful atten­ climate. An example is possible altera­ tion to the statistical design of experi­ tion of the oceanic heat balance by ments; a larger program in computer lifting cold water to the surface in simulation and laboratory geophysical major currents such as the Gulf Stream modeling; and consideration of syn­ or Kuroshio (Japan) Current. Such ex­ chronous satellites for observing the periments should obviously not be life history of storms such as hurri­ undertaken without many years of in- canes.

17 have insured more adequate biological RIOLOOIUL IMPLICHIONS information concerning artificial sys­ tems, and because these systems are Man is an organism directly de­ not so complex biologically. It is es­ pendent on other organisms for many sential that this present primitiveness of his materials. He also struggles in our biological forecasting capability with other organisms, most of them not be used as an argument for omit­ quite small, that prey upon him, eat ting it from weather modification pro­ his food, or otherwise challenge his grams. existence. Anything that has a general Prediction of the types and degrees and significant effect upon plants and of change in crop and livestock yield animals, making some more abundant, and quality to be expected from spe­ others less so, is of primary concern cific changes in weather sequences to mankind, for it strikes at the very can be markedly improved with meth­ basis of human existence. Changes in ods and analyses already at hand. weather and climate may be expected Prediction of the direct effects of to have such effects. It follows that weather changes on the domesticated any program of weather and climate organism can be attained more modification must give serious atten­ quickly than prediction of the indirect tion to adverse as well as beneficial effects resulting from weather-in­ biological aspects. duced changes to the domesticants' It must be recognized that the pres­ parasites, diseases, pests and symbi­ ent state of knowledge places uncom­ ants. The published literature contains fortable demands on the prediction of many references to studies implicat­ the biological consequences of modi­ ing unusual weather sequences for fying the weather. Prediction of the disease and insect and weed out­ impact of weather modification on the breaks. Vector-born diseases of plants biological components in man's arti­ and animals, humidity-responsive bac­ ficial ecological systems such as his terial and fungal diseases of crops and cities and his farms will probably be many insect outbreaks can be cited as easier to attain than such prediction examples. A fuller knowledge of these for the more nearly wild areas. This inter-relations coupled with a capabil­ is so, because economic objectives ity of highly accurate control over the

18 weather could have favorable eco­ during instability, the net economic nomic results. Ignorance concerning effect is difficult to predict. the biological consequences to be ex­ In vast reaches where the biological pected from significant changes in the communities extend beyond the areas weather could be locally detrimental. of weather modification it can be ex­ In wild lands the complex natural pected that natural migrations of arrays of organisms are in delicate species from areas adjacent to the adjustment not only with the normal changed condition will tend ulti­ climate but also with the pattern of mately to restore stability. However, fluctuations. On the basis of the few in the small islands of natural bio­ published long-term studies in which logical communities such as parks and biological composition has been fol­ preserves the effects will be less apt lowed during major weather fluctua­ to set themselves right. The wide tions, it seems a reasonable prediction stretches of man's artificial biological that alterations in weather patterns make-up and disturbance between are likely to constitute at least a tem­ such islands provides an effective bar­ porary unstabilizing influence in most rier to migrations. Extinction, at least natural biological communities. It is locally, could result for some species. important to note that weather and Thus, from the present crude state climate fluctuations have been a mold­ of the field, one can roughly predict ing influence on natural populations that the biological outcomes of and most species have adaptations re­ weather modification are apt to be a lating to it. Thus, weather and climate mixed bag of economically good and modifications need not constitute bad effects in man's artificial ecosys­ changes exceeding the recorded ex­ tems. It is difficult to visualize any tremes in order to cause significant desirable effect on the small preserves biological consequences. Some of the of natural communities. In order to successional species that tend to in­ improve biological forecasting several crease during instability may be eco­ avenues are open: nomically important species such as 1. Growth chamber simulation of the succession of many forest species. such changes on as large a fragment Since many pests are also favored of the biological type as possible.

19 Examination of areas biologically the natural ones from which he de­ and climatically analogous to the rives an essential part of his inspira­ changed and unchanged situations. tion and contentment. Study of the fine structure in the All five of the above approaches fossil record of the recent past. need to be brought to bear on the Computer simulation of changes problem. Any group involved with using the best available data. large-scale experimentation with Monitoring of sample areas weather modification should be ex­ within and outside of regions sub­ pected to provide for adequate bio­ jected to weather modification. The logical monitoring. The team effort monitoring should begin before that would result from this kind of weather modification activities and interaction of meteorologists, hydrolo­ extend beyond their cessation. gists, engineers, ecologists, agrono­ mists, foresters, entomologists, etc. is It is the position of the Commission long overdue. that there should be a strong effort to bring the field of biological fore­ casting up to a higher level of useful­ THE SOCIAL EFFECTS ness. This is mandatory in planning weather and climate modification over Weather and climate conditions are areas involving more than a few hun­ among the major determinants of eco­ dred square miles. nomic activities and social structure. A by-product of such expanded re­ No other aspect of the environment search and development will have has as many pervasive relations to wide utility in agriculture, forestry the pattern of human activity on the and park and general resource man­ globe. Any substantial change in pre­ agement and other fields. Beyond this, cipitation, temperature, or wind, as an area of fundamental science, whether deliberate or inadvertent, is forecasting of the behavior of eco­ likely to have a significant effect upon logical systems needs to be augmented society, as the public and private ex­ since man knows so very little about penditures for hurricane, drought, and how such systems operate, either the flood disasters dramatically illustrate. man-made ones that sustain him or The immense varieties of housing and

20 of farm cropping practices illustrate and the apparent immediate value of less obvious but fundamental adjust­ the products for the market are so ments to weather and climate. In some divergent. cases the influence of weather and A number of techniques are avail­ climate modification on human activ­ able for study of the economic and ities may result in shifts of the social social impacts of weather modifica­ institutions that are too subtle to be tion. These include benefit-cost analy­ recognized by many of those involved. sis, activity analysis, input-output If scientific research in changing analysis, and analysis of decision weather and climate is regarded as making, as well as numerical simula­ an investment decision, society should tion studies. Despite differences of seek answers to several questions as opinion as to research , the it decides how much to spend for various techniques tend to be comple­ what kinds of research. Who benefits mentary. Much has been learned about from the investment if made? If both methods from the social appraisal of benefits and losses occur, how are engineering projects to modify the they distributed? Will the normal water cycle in river channels. market forces provide enough incen­ One general approach is to define tive to achieve the socially optimum an actual or assumed modification of results to mankind? the weather and then attempt to an­ It does not seem plausible that pri­ alyze the full consequences of this to vate enterprise will finance research society. It is practical, for example, to at a level adequate to achieve the estimate an increase in precipitation optimum social objective. Further, over a drainage area serving a hydro­ because the benefits or losses do not electric plant and then follow the pos­ necessarily accrue to people in the sible impacts through the operation of same geographic area or in the same the plant, the operation of downstream businesses, weather and climate modi­ water projects, the production of fication research needs to be sup­ other plants connected in the same ported primarily from federal sources system, and the productivity of the for the foreseeable future. This posi­ entire network. Along with the cost tion is to be expected when the esti­ of cloud seeding, an attempt can be mate of the long-range social effects made to measure the full social bene-

21 fits and costs from the increased rain­ how they will react if the atmosphere fall, but these are hard to identify. is modified. Another approach is to analyze a Any adequate evaluation of social sector of society so as to determine effects examines and compares the the particular points in the life of whole range of alternatives to weather man where he is sensitive to changes and climate modification. An accurate in weather, and the degree to which weather forecast, for example, may a modification might lead to readjust­ be more valuable than an increase in ment in amount or location of his rainfall, in some situations. If long- activity. For example, it is obvious range forecasts were made reliable a that the whole pattern of recreation farmer could change his cropping pat­ in an area can shift very quickly tern for that year rather than support because it happens to rain or at weather modification. As a further il­ a given time and place, and that if lustration, unless practical triggering the probability of precipitation were mechanisms can be found, increasing to be changed, the character of the the ability to forecast tornadoes and regional recreation industry would hurricanes is more rewarding than at­ alter. tempting to modify them. Adequate A basic difficulty in social research warning in many cases can allow man associated with weather modification to adapt his activities at lower cost. is the difficulty of assessing the way There are other alternatives in ad­ in which man responds to a known dition to forecasting: agronomic and weather circumstance. Just because genetic research can render farming there is a drought it does not auto­ less susceptible to the vagaries of matically follow that a farmer in that weather. Engineering can protect area will move to another locality or transport from weather interruptions. adopt a different cropping schedule, A change in farm or industrial organi­ even though analysis indicates it zation can reduce its vulnerability to would be most profitable to do so. He weather extremes. may decide to stay, or to hold to his The need is great to assess more old farming methods. Understanding fully the social implications of weather how people manage natural resources and climate modification resulting is essential to sound prediction of from man's discharging material into

22 the atmosphere. As more is known remain unexplored until a major prob­ about the weather man could decide lem erupts. The Commission feels to build cities on spoil areas rather strongly this should not be the course than on good farm land and in topo­ of events in the future. All agencies graphic areas which help avoid pollu­ engaged in weather modification at­ tion of the environment. One alterna­ tempts should give systematic atten­ tive here, of course, is to modify the tion to the social implications. It is weather over urban areas deliberately essential that funds be allocated for to offset the results of man's inad­ corollary research in the social sci­ vertent weather changes. ences as related to weather and cli­ To the uncertainty as to what mate modification, both deliberate and weather and climate modification man inadvertent. This research should em­ can accomplish must be added his brace the measurement of impacts, lack of knowledge of the full conse­ the identification of basic geographic quences. New research programs relationships between human activity should be based on the recognition and weather and climate, and the con­ that expanding the scientific knowl­ ditions under which decisions about edge of these consequences would be weather are made. important to man even if no further gains were to be made in the technol­ ogy of weather modification. The same THE UW understanding which would permit as­ sessing the effects of weather and The ramifications to society—and climate alteration would assist in hence to our legal system—of the working out other kinds of adjust­ technological capability to order ments to weather phenomena. weather would be enormous. Even a As indicated by the lack of social limited capacity to modify weather research about weather modification poses legal problems of great com­ since the 1957 report of the Advisory plexity. Urgent as these problems may Committee on Weather Control, when soon become, uncertainty as to the uncertainty concerning the feasibility scientific capability makes the recom­ of extensive weather modification is mendation of long-range legal solu­ large the social implications tend to tions impossible at the present time.

23 Nevertheless, the law is already in­ on participation in government pro­ volved with weather modification and grams. it is necessary to come to grips now As to regulation, some twenty-two with some aspects of the problems. states have enacted laws regulating The involvement of the law with weather modification. Most of these weather modification is of two kinds: statutes require licenses. One state the rules governing the responsi­ prohibits weather modification activ ­ bilities and liabilities of weather mod­ ities entirely. While these statutes ifiers to other members of the public; have had little effect on weather mod­ regulation by government. As to ification activities, there is a distinct the former, it is premature to make possibility that they may interfere any recommendations concerning the with desirable Federal programs in rules of law which should be adopted the future. to govern "property rights in weather," Until recently the only Federal or the liabilities of weather modifiers "regulation" was the requirement by with respect to those claiming injury the National Science Foundation for to their persons or property. It is to reports on activities already under­ be hoped that problems of weather taken by operators of whose activities modification will be decided on their the Foundation was aware. Effective own merits rather than on the basis January 1, 1966, the Foundation sub­ of too facile analogies to the law re­ stantially increased its record-keeping specting land, water, wild animals, requirements and imposed on all op­ airspace, and the like. The few court erators a requirement of advance no­ decisions to date, while useful in il­ tice to it of any activity. lustrating the kinds of conflicts which The present authority of the Foun­ can be expected to arise, do not give dation under Public Law 85-510 pro­ much basis for predicting how the vides for obtaining—by regulation or law will develop. As the law stands, otherwise—information, including ad­ however, government contractors and vance notice of any proposed weather grantees are subject to a risk that modification activities, deemed neces­ liability will be imposed on them for sary to its program of study, research, damage caused by their activities and and evaluation. This information is an that risk may have an inhibiting effect aid to the Federal research and devel-

24 opment effort and to the protection of protection against liability to the pub­ its integrity. But, the lack of Federal lic for damages caused by Federal pro­ authority to stop activities which may grams of weather and climate modifi­ interfere with or contaminate Fed- cation. erally-supported programs renders the These recommendations are delib­ Federal government powerless to pro­ erately restricted in scope, in the be­ tect its programs from the actions of lief that in the developmental stage of privately supported parties or state weather and climate modification the and local instrumentalities except by minimum regulation consistent with voluntary arrangements. immediate goals is desirable. How­ Thus, the Commission recommends ever, it should be recognized that as that the Federal government, by ap­ knowledge develops and as weather propriate legislation, be empowered and climate modification activities in­ to: crease, more comprehensive regula­ tion in the public interest may be delay or halt all activities—pub­ required. Such regulation might in­ lic or private—in actual or potential clude setting standards of profes­ conflict with weather and climate sional qualifications and financial modification programs of the Federal responsibility for operators, establish­ Government, whether these programs ment of appropriate authority for de­ are conducted for the Federal govern­ termining which experiments or oper­ ment, by its own agencies or by its ations may be undertaken in the public grantees or contractors; interest, and a requirement of evalua­ immunize Federal agents, gran­ tion of activities by the operator. tees, and contractors engaged in Finally, since weather no more re­ weather and climate modification ac­ spects national boundaries than it does tivities from state and local govern­ State lines, it is hoped that early ef­ ment interference; and forts will be made to delineate and provide to Federal grantees and study the international legal problems contractors indemnification or other of weather and climate modification.

25 or climate modification are expanded NEEDS AND OPPORTUNITIES in scope and number and involve ac­ tual attempts to introduce changes in FOR INTERNATIONAL COOPERATION the atmosphere, some form of interna­ tional collaboration will be essential The program of research required in the planning and execution of proj­ to develop the capability to modify ects that may have an effect not only weather and climate suggest a strong upon the immediate localities but on emphasis upon international coopera­ areas in other countries and even tion. The extensive and significant upon other continents distant from work that is being done in other coun­ the scene of work. It is possible that tries underscores the need for pro­ situations of this sort may arise in moting the international exchange of the near future if an expanded pro­ data and research findings for the pur­ gram of field experiments in cloud pose of maximizing their usefulness. seeding is undertaken in areas near The need for international collabora­ the northern or southern borders of tion in the actual planning and con­ the United States. An expansion in ex­ duct of research activities may be perimentation with tropical hurri­ expected to increase as research moves canes may also present international out of the laboratory and into the complications. realm of field experiments associated In the present stage of world affairs with the study of the dynamics of any scientific advance contributing climate, the establishment of a global significantly to man's ability to affect weather observation network and the the natural environment inevitably investigation of other aspects of the has a bearing upon the political rela­ general atmospheric circulation. The tions among nations and the quest for technological and human resources re­ peace and security. The importance to quired for the conduct of this type military operations of a capability for of research are far beyond the capabil­ modifying weather conditions is obvi­ ity of most countries to provide indi­ ous. It must be recognized that there vidually. is a remote possibility that sometime Looking into the future to the time in the future a nation might develop when field experiments with weather the capability to use weather modifi-

26 cation to inflict damage on the econ­ The very fact that the development omy and civil population of another of a capability for influencing the at­ country. mospheric environment is still in its It is essential to develop the politi­ infancy should widen the opportunity cal and social controls over the use presented by this scientific endeavor of this power which will maximize the to develop attitudes and patterns of opportunities for its constructive and collaboration which can contribute peaceful use and minimize the factors not only to the achievement of the which tend to involve it in the ten­ practical, technological goals, but also sions and conflicts inherent in human to the relaxation of international ten­ society. The challenge and the oppor­ sions. tunity which are presented to the Rarely has a more ample and in­ world community by the prospect of viting opportunity been offered for man's achieving a power to modify advance thinking and planning re­ his atmospheric environment is one of garding the impact of a technological the most exciting long-range aspects development upon international rela­ of the subject. tions. Progress in the diminution of Thought must be given to the types international tensions and the achieve­ of international organizations that will ment of peace will come not so much be needed, and the functions they from the dramatic resolution of basic should perform, if and when major international controversies as from operations in weather and climate the far less spectacular widening of modification affecting large continen­ areas of mutual interest among rival tal areas become feasible. Whether nations and from the growth in ways the assignment of operational respon­ of cooperation. The field of weather sibility to an international agency and climate modification can serve should be considered for the future well in this regard, in addition to deserves thought even at this early realizing benefits of a more limited date. Consideration might be given to practical nature. new concepts of international organi­ zation and to the new problems of a The Commission believes that: technical or political nature that 1. It would be highly desirable for might be precipitated. the Government of the United States,

27 in connection with the expansion of ately incorporated in any basic legis- its program of weather and climate lation on the subject of weather modi- modification, to issue a basic state­ fication which the Congress may enact. ment of its views on the relationship Steps should be taken by the of this national effort to the interests, United States, in concert with other hopes, and possible apprehensions of nations, to explore the international the rest of the world. Early enuncia­ institutional mechanisms that may be tion of national policy embodying two appropriate to foster international co­ main points are recommended: operation and cope with the problems that it is the purpose of the which may be anticipated in the field United States, with normal and due of weather and climate modification. regard to its own basic interests, to The and its special­ pursue its efforts in weather and cli­ ized agencies (e.g., the World Meteor­ mate modification for peaceful ends ological Organization) is suggested as and for the constructive improvement a possible intergovernmental frame­ of conditions of human life through­ work. The International Council of out the world; and Scientific Unions and its associated that the United States, recog­ unions (e.g., the International Union nizing the interests and concerns of of Geodesy and Geophysics) could be other countries, welcomes and solicits a suitable non-governmental frame­ their cooperation, directly and through work for these mechanisms. international arrangements, for the A major limitation affecting both mutual achievement of human well­ advanced and developing countries is being. the shortage of trained personnel in This cooperation should cover both atmospheric sciences at all levels. At­ research and, ultimately, operational tention should be given to the ques­ programs of interest to other coun­ tion of how greater emphasis can be tries. It should be concerned not only given to atmospheric sciences in ex­ with deliberate, but also inadvertent isting bilateral and multilateral pro­ human interventions in the atmos­ grams of education and technical phere that affect weather and climate. cooperation; and to what additional Such a policy declaration could be measures may be needed to fill this issued by the President or appropri- deficiency.

28 4. Encouragement should be given warranted by the evidence presently to research on the impact of weather at hand are as follows: modification measures in foreign There should be a strengthened countries. The need has been previ­ program of fundamental research in ously discussed for greater attention the atmospheric sciences and the ini­ to the biological, economic and social tiation of complementary research in aspects of weather modification in the the biological and social sciences. Re­ United States. A different set of prob­ search in the atmospheric and the lems may well be encountered in many biological sciences should range from of the developing countries where the studies of a large and extensive nature natural environment and patterns of involving many individuals and sub­ economic and social life present con­ stantial logistical support to the work trasts to those prevailing in this coun­ of individual investigators. Desirable try. A greater understanding of the research on socio-economic aspects significance of these differences must and the legal and international impli­ precede any attempt to evaluate the cations will generally consist of stud­ suitability of various weather and cli­ ies of relatively modest cost. mate modification practices for spe­ There should be a concerted ef­ cific foreign areas and to design ap­ fort directed specifically at the devel­ propriate programs of cooperation. opment of what may be called the technology of weather and climate FISCAL AND OROANIZATIONAL modification. This is a sector in which a conspicuous gap is becoming evi­ CONSIDERATIONS dent. The objectives should be early development and testing of techniques by which deliberate intervention in Scope ano Nature 01 the atmospheric processes can be accom­ plished and consideration of the National Program likely consequences of human activity in inadvertent intervention. Large- The four principal elements of a scale undertakings with substantial national program for weather and cli­ logistical support will be required and mate modification that appear to be close liaison will be desirable with

29 the social, biological and other related They will require logistical support of studies. substantial proportions in the form, There should be provision for for example, of suitable instrumenta­ operational application by both the tion, aircraft, synchronous satellites public and the private sectors as the and ecological laboratories. Some idea feasibility and efficacy of modifica­ of the costs for which provision tion techniques are validated. should be made is given by the esti­ There should be such regulation mate that a field experiment on hail as may be required to protect the by use of doppler radar and aircraft public interest and advance the state would cost at least $2 million a year. of the art. Admittedly, it is difficult to The weather and climate modifi­ arrive at a judgment on such matters cation program needs a strong cen­ as the timing and necessary scope of tralized group as could be provided by regulation and the form of administra­ a national laboratory. Such a group tion. In the opinion of the Commis­ or center could serve as a focal point sion, however, it is not too soon to for research and development to con­ deal with this matter providing flexi­ duct and assist in large scale experi­ bility for adaptation to changing needs. ments and to provide logistic capabil­ ities. The availability of a center with its facilities would serve as a nucleus funding for program planning and interchange of scientists on an international basis. In the light of the above program, It should be interdisciplinary in char­ the following considerations with re­ acter and provide for the conduct and spect to funding appear to be revelant. support of research in those physical, Federal financial support for re­ biological and social sciences which search and development activities in are involved in weather and climate weather and climate modification modification. needs to be increased substantially Federal outlays for weather and above present levels. climate modification research and de­ Large field observational pro­ velopment in 1966 ap­ grams and experiments of both a basic proximate $7.2 million, exclusive of and an applied nature will be costly. logistical support provided by the

30 Department of Defense. This sum con­ tivity; it is natural that several Federal stitutes about two percent of the ex­ agencies have been involved as they penditures of all Federal agencies for fulfill agency missions. In the last full the atmospheric sciences and meteor­ fiscal year, 1965, the Departments of ological services. The potential im­ Agriculture, Commerce, Defense and portance of weather and climate Interior and the National Science modification, its propects for the Foundation all expended funds for future even in the face of remaining weather modification. No single uncertainties in the present state of agency in the Federal government now the art, and the magnitude of the ef­ has responsibility for developing the fort that may be required to resolve technology of weather and climate these uncertainties, require substan­ modification. The need for such desig­ tial funding. The Commission believes nation is now, however, becoming that by 1970 annual funding should be evident. increased to the neighborhood of $20 The future requirements of the to $30 million, including logistics sup­ agencies, and the needs of the weather port, or about five percent of the total and climate modification field, suggest for atmospheric sciences and meteor­ that the organization of a national ological services. In addition, increases program should be unified around one of the same order will be needed for agency, yet open for the participation underlying basic research, including of those agencies whose missions re­ funds for items such as large com­ quire the conduct or support of puting facilities. Thus a total increase weather and climate modification ac­ of $40 to $50 million per year may tivities. The national program needs be envisaged by 1970. The level of to provide for agencies such as the funding must, of course, be constantly Federal Aviation Agency, which might reviewed as progress is made. operate over an area as small as an airport, to the State Department with its concern over the relationship of Organizalional ROSOORM1111183 weather and climate modification to foreign policy. Thus, a national pro­ Weather and climate modification gram should provide for the diversity pervades many facets of human ac- of intellectual interests associated

31 with the subject, field and laboratory rected at providing a satisfactory sci­ projects both large and small, and a entific basis for weather and climate growth in financial support consistent modification. This should be carried with prospective results. on primarily at universities and col­ leges and should include maintenance The Commission takes the of the National Center for Atmos­ position that: pheric Research as a facility for the conduct of basic research on a scale The mission of developing and beyond that feasible for individual testing techniques for modifying university investigators. The degree weather and climate should be as­ of continuing and special attention signed to an agency in the Executive given by the Foundation to the sup­ Branch of the Federal Government- port of the physical sciences, engi­ for example, to the Environmental neering, the biological sciences and Science Services Administration of the social sciences aspects of weather the Department of Commerce or to a and climate modification should be completely new agency organized for reviewed from time to time in the the purpose. The mission should in­ light of the progress of the over-all clude support and conduct of research national program. and development and such operational Federal agencies should under­ activities as are needed for the fur­ take such operational activities as therance of the technology of weather may be required for the effective dis­ and climate modification. This agency charge of their missions (e.g., sup­ should have major but not exclusive pression of lightning by the Forest responsibility, in collaboration with Service, fog dispersion by the Federal the State Department, for formulat­ Aviation Agency and rainfall augmen­ ing and implementing programs of tation for the reservoir system of the weather and climate modification in­ Department of the Interior). Also, volving international cooperation. pursuant to Executive Order 10521, The National Science Foundation Federal agencies should be free to should continue and expand its sup­ conduct and support such research port of research in the atmospheric and development as may be required sciences, including its program di- in the discharge of their missions.

32 (4) Insofar as the nature of a regu­ It must be recognized that because latory agency is concerned, care must the social effects will be complex and be taken to ensure access of all agen­ because Federal agencies are associ­ cies to the information generated, ated with diverse interest groups there while at the same time keeping regu­ are likely to be major conflicts in pro­ lation organizationally separated from grams. Such conflicts go beyond the research and development. For ex­ scope of regulation and involve admin­ ample, were the assignment of regula­ istrative coordination at the highest tory responsibility to be made to the level. Their resolution should not be Secretary of Commerce, provision left to a regulatory agency. The Com­ should be made that it be exercised mission recommends that the Office outside those parts of the Department of Science and Technology should engaged in the conduct of research and consider establishment of a special development relating to weather and mechanism for the coordination of climate modification. Whether the reg ­ weather modification policies and pro­ ulatory function needs to be divorced grams. Such an entity could not only completely from the operating agen­ serve to resolve conflicts but could cies, or can be assigned to a separate serve to promote unity in policy and branch of such an agency, will depend deployment of funds and manpower with optimum effectiveness. largely on the extent of activity and 5. Both the Executive Branch and the degree of regulation required. the Congress may wish to have avail­ As to the jurisdiction of a regula­ able scientific and public policy advice tory agency over other Federal agen­ from a group of knowledgeable people cies, insofar as regulation involves from outside the Government. This requirements of notice, reports, licens­ need might well be met by the appoint­ ing of activities, etc., there seem to be ment of a standing committee in the good reasons why all agencies should National Academy of Sciences in co­ be subject thereto. In addition, the operation with the National Academy regulatory agency should be given of Engineering. The group should in­ power to resolve minor conflicts be­ clude persons with experience in the tween agencies, such as the timing of physical, biological and social sciences particular experiments. and engineering.

33 chapter. A brief summary of some of INTRODUCTION the most important conclusions of the PROORESS NAS Panel is included in Section III. For a review of the present status Also ircluded in this chapter are brief and potential of weather and climate discussions in Section IV of some of AND modification, the Commission has de­ the projects on weather modification pended mainly on the report of the research carried out under the Na­ Panel on Weather and Climate Modi­ tional Science Foundation program. PROSPECTS fication of the National Academy of In Section V there is a review of Sciences *, the annual reports of the activities in foreign countries. Finally IN WEATHER National Science Foundation, and the in Section VI a discussion is given in report of Gilman, et al.** Since the broad terms of prospects for future scientific basis has been discussed research. AND CLIMATE thoroughly in these reports, there is no need to repeat it here. Instead of a detailed discussion, an attempt is made THE NATURE OF THE MOFICATION here to delineate the problem in its broadest conceptual framework in SCIENTIFIC PROBLEM order to describe the probable charac­ ter of a well balanced plan for future The atmospheric envelope rotates action. with the earth, but does not rest Consideration of the physical prob­ quietly upon it. Air motion relative to lems involved properly begins with a the earth is induced by a non-uniform brief review of the atmosphere as a distribution of energy sources and physical system, the dimensions of the sinks which are strongly influenced by quantities of energy that would be those motions which they produce. required to alter atmospheric processes by the exercise of brute force, and the * Weather and Climate Modification- Problems and Prospects, Vols. I and II, Na­ nature of the instabilities that might tional Academy of Sciences-National Re­ be exploited to exert meaningful influ­ search Council, 1966 (NAS-NRC 1350). ence within the limits of our ability ** Weather and Climate Modification, A Report to the Chief, United States Weather to manipulate energy. These problems Bureau, July, 1965. (Both these reports in­ are discussed in Section II of this clude extensive bibliographies.)

34 The motions themselves range in size able consequences. To be intellectu­ over a spectrum that extends from the ally satisfying, the cause and effect scale of planetary wave systems down relationship would have to be under­ to molecular movement. The sources stood in precise and exact detail. To and sinks of energy are variable in be meaningful in a practical sense, it is number and strength and exist mainly only necessary to establish beyond a in response to the disposition of short­ reasonable doubt that the cause and wave solar radiation, the flux of out­ effect are related. going long-wave radiation, the latent It is useful to consider the order heat involved in the phase change of of magnitude of the kinetic energy water and on the flow of sensible heat involved in several scales of atmos­ between the lower atmosphere and the pheric subsystems. Some idea may be underlying ocean or land. The kinetic obtained from the following table: energy of air motion is continuously Atmospheric � Approximate* exchanged with other forms of energy Subsystems� Energy in ergs in the atmosphere and the kinetic funnel�1021 energy of the several scales of atmos­ Small �1022 pheric is continuously being trans­ Large thunderstorm �1028 ferred from one scale to another. Hurricane� 1025 For the purpose at hand, the atmos­ Extratropical �1026 phere may be viewed as a complex General Circulation in the physical system in which ascertain­ Northern Hemisphere 5x10 27 able changes in air motion take place * Data for the tornado funnel and thunder­ in response to identifiable forces. In storms refer to a total lifetime of kinetic energy. Data for the other phenomena refer principle, by altering these forces, con­ to kinetic energy at any given moment during sequent changes in the air motion can maturity—which may be considerably less be influenced. Thus, in principle, con­ than the lifetime expenditure. trolling the weather or modifying An appreciation of the energy require­ the climate is scientifically possible. ments necessary were the kinetic Whether or not it is practically realiz­ energy of these atmospheric subsys­ able depends on a demonstration of tems to be changed by 10 percent can the capability to alter these forces in be obtained from the next table. The a manner which will produce predict- column on the right lists the time

35 demand on the total electrical energy will be seen presently, there exists generating system of the United States some evidence that increases in rain­ if that source were to be drawn upon fall of this order may be obtained by to change the kinetic energy of the seeding. A triggering mechanism based atmospheric subsystem by ten percent. on an atmospheric instability is in­ Atmospheric � Approx ima te * volved. It is appropriate, then, to con­ Subsystem� Time sider the question of possible insta­ Tornado� 30 seconds bilities in the atmosphere. Small thunderstorm�5 minutes From simple observations of the life Large thunderstorm several hours cycle of cumulus clouds, thunder­ Hurricane� several days storms, tornadoes, hurricanes, and �5-6 weeks extratropical cyclones, it is evident General circulation in the that—within certain limits—the atmos­ Northern Hemisphere �6 years phere is unstable, that is, the ampli­ * Data for the tornado funnel and thunder­ tude of disturbance increases with storms refer to a total lifetime of kinetic time over a period of time which energy. Data for the other phenomena refer to kinetic energy at any given moment during varies with the size of the disturbance. maturity—which may be considerably less Moreover, significant energy transfor­ than the lifetime expenditure. mations are involved in the amplitude One concludes that it is not immedi­ growth associated with these releases ately practicable to think of altering of energy initially in unstable form. these atmospheric subsystems to this At least four kinds of instability have extent by a direct application of been identified as potentially suscepti­ energy. Nor is it reasonable to think ble to man's efforts to trigger natural of using energy directly to alter rain­ reactions. They are: fall. For example, the additional latent heat released by an increase of 10 per­ 1. The phase instability of water cent in a rainfall totaling one inch in the vapor phase in a condi­ over an area one hundred miles on a tion of supersaturation and in side would be the equivalent of about the liquid phase in the condi­ six days of the daily output of the tion of supercooling which, electrical generating capacity of the when released, provides a local United States. On the other hand, as source of sensible heat.

36 The colloidal instability of is provided, however, by the indica­ cloud particles which when tions that energy can progress upward released by precipitation, com­ through the several scales of exchange. pletes the cycle by which latent It is pointed out in Volume II of the heat is exchanged between the NAS Panel report that: underlying surface and the atmosphere. The release of phase insta­ The convective instability of bility in an aggregation of super­ the atmosphere which, when cooled cloud drops can simul­ released, redistributes sensible taneously colloidally destabilize energy in the vertical and often the cloud into precipitation produces high local concentra­ (through the Bergeron-Findei­ tions of kinetic and electrical sen mechanism) and, through energy. the introduction of latent heat of fusion, convectively desta­ The baroclinic instability of bilize the volume of air within the large scale circulation which the phase change is oc­ which, when released, redis­ curring. All of this has been tribute sensible and kinetic energy in the horizontal plane, observed, on a very small scale, i.e., from pole to equator. in the seeding of stratocumulus clouds. It is not hard to imagine The results of preliminary experi­ that induced or mentation with the first three instabili­ induced snowfall on a much ties identified above lend support to larger scale could sufficiently the point of view that they may be the alter the horizontal temperature "Achilles' Heel" in the atmospheric distribution to trigger or subdue system by which large effects might be baroclinic instability, changing produced by relatively modest, but the natural development of highly selective, interventions. The large cyclonic storms. This, in difficulties of treating quantitatively turn, might alter the global radi­ the non-linear processes inherent in ation balance and thus influ­ instabilities are sobering. Some offset ence a fifth scale of instability

37 about which we can only con­ jecture: the possible instability PRESENT STATUS OF of global climate. WEATHER MODIFICATION The great variability of an­ The reports cited in the Introduction cient climates is accepted as to this chapter give excellent discus­ fact, yet the cause of climatic sions of the present status and prom­ change is far from being a set­ ise of weather and climate modifica­ tled issue. It is obvious that the tion. earth-atmosphere system can A brief summary of some of the support radically different cli­ more important findings is given here. matic regimes, some of which Some aspects of weather and climate could be disastrous to civiliza­ modification are ready for practical tion. We do not yet know what applications, others are sufficiently can cause a shift from one promising to warrant programs of climatic regime to another, mission-oriented or applied research, whether change can occur in an still others are more remote possibili­ "instant" of geologic time or ties for which no more than basic re­ only as a secular, cyclic proc­ search can be justified at the present time. Furthest advanced is the prob­ ess; our few theories still hang lem of dissipation of supercooled fog on the most tenuous of evi­ and stratus clouds by seeding, which dence. has reached the stage of engineering applications for clearing of fog at air­ This, in barest outline, is the nature ports. Experiments done here and of the problem and some of its impli­ abroad on cloud seeding for local in­ cations. It is appropriate now to turn crease of precipitation and for sup­ to some advances in recent years that pression of hail and of lightning, while suggest the present moment to be a far from conclusive, have shown some propitious one to accelerate and promise of success. Vigorous pro­ strengthen the systematic exploration grams of applied research should be of the question. pursued in these areas to delineate the

38 potential and to optimize the proce­ dures used. clearing of Supercooled Without many more years of basic SIMUS and Fog research on large-scale circulations of Effects of seeding by dry ice and by the atmosphere and the causes of cli­ silver iodide were first demonstrated matic change, no program of modifica­ upon supercooled stratiform clouds. tion of climate extending over large Recently attempts have been made to areas of the earth's surface could or develop operational methods for clear­ should be undertaken. Such a research ing of supercooled fog at airports. program, although difficult and expen­ Such methods have been used here sive, can be justified for aid in long- and abroad for the past several years, range forecasting and for making pos­ particularly in the USSR, where the sible predictions of consequences of problem is more severe. Clearing of inadvertent changes in the atmos­ warm fog is much more difficult and phere caused by activities of man. The no really satisfactory methods have been proposed. possibility that such a program will in the future suggest methods for bene­ ficial modification of climate is added of tocai Precipitation incentive for undertaking it. Increase Given below is a brief summary of uY seeding some of the main conclusions of the reports on the present status of It has long been controversial as to whether local precipitation can be weather modification. A review is then enhanced by seeding. The NAS Panel given of some of the research pro­ has made a statistical study of com­ grams on weather modification under­ mercial seeding operations mostly taken during the past few years both using ground-based silver iodide gen­ here and abroad. The summary is nec­ erators. Included were operations in essarily quite brief; the reader is re­ the Eastern U.S. and in orographic ferred to the reports cited for detailed situations in the Western U.S. In addi­ information and background. tion, preliminary results of several

39 randomized experiments on seeding order of io% by seeding. These posi­ both in this country and abroad have tive results are obtained in cases become available during the past year where rain would have fallen anyway and are included in the study. In Vol­ without seeding; there is no evidence ume I of the NAS Panel report it is that seeding can induce rain to fall stated: "There is increasing but still when normally there would be none. somewhat ambiguous statistical evi­ Thus, seeding is of limited value in dence that precipitation from some relieving drought situations. types of cloud and systems can There is very tenuous evidence that be modestly increased or redistrib­ there may be under certain circum­ uted by seeding techniques. The im­ stances a "rain shadow" effect, an plications are manifold and of imme­ area of decreased precipitation down­ diate national concern." The statement wind from the area of enhancement. cannot be made more conclusive be­ There is no reason to suspect that this cause of the possibility of some un­ might be caused by "rain out" of avail­ known source of bias or systematic able moisture, since normally only a error in the commercial seeding oper­ fraction is released as rain in any case. ations and because chance fluctuations Theoretically, one could have consid­ cannot be completely ruled out as an erable enhancement of local rainfall explanation of the more limited ran­ without appreciable influence on pre­ domized tests. It should be empha­ cipitation further downwind. sized that the problem is an extremely complex one; there is great variability in cloud types and in ways in which rncrease ol rreciniiahoo precipitation can occur. The theoreti­ cal knowledge of how seeding nuclei by FORM COUVOCHOR are introduced into clouds from ground-based generators and how pre­ Suggestions have been made that pre­ cipitation may be affected thereby is cipitation in some local areas could still quite rudimentary. be increased by changes in the earth's Present indications, if taken at face surface to promote great absorption value, are that local precipitation can of heat and also greater transfer of be increased in many situations in the heat and to the atmos-

40 phere. This would stimulate convec­ strips) into clouds to decrease electric tion; hopefully in sufficient amount to field gradients. increase cloudiness and precipitation downwind. While some plans have been formulated, no field tests have Hall Suppression been made to test this proposal. An­ other method, which has given some Studies of suppression of hail by seed­ indications of success in limited trials, ing or other techniques have mostly makes use of seeding. It has been sug ­ been carried out abroad and with in­ gested that latent heat released by in­ conclusive results. There are reports creased condensation of moisture into that Soviet scientists by introducing water droplets causes uplift and cloud seeding nuclei at the optimum posi­ formation. It may be that some of the tion and time by use of antiaircraft observed increases in precipitation by shells have had success, but this work cloud seeding result from enhanced has not been duplicated in this coun­ convection rather than directly by try. Volume I of the NAS Panel report nucleation of droplets. states that "the U. S. hail research program is piecemeal and clearly of sub-critical size." Plans are underway LWIIIAIDO suppression by the National Science Foundation to initiate a program in this area. Studies carried out under Project Sky- fire of the U. S. Forest Service for the past several years have given indica­ Mofleratiog severe siorms, tions that seeding can alter cloud to IND ground lightning from thunderclouds. TornaOoes, and Hurricanes Background has been developed for a more thorough statistical study to see Under , several at­ under what conditions seeding may tempts have been made to modify be effective in reducing lightning and hurricanes by seeding. The intent is lightning-caused forest fires. Another to produce warming in the outer zone suggestion, not yet tested on a large of the wall by releasing latent scale, is to introduce chaff (metallized heat of fusion and so alter the pres-

41 sure and wind distributions. Results earth's surface will be discussed in are so far inconclusive. Progress in more detail later in this chapter. these areas, where tremendous ener­ gies are involved, will require much further basic research involving ex­ Nimmons 01 comaie tensive field investigations and devel­ opment of theoretical models. For the future welfare of mankind it is important to be able to understand the factors involved in climatic change mominu me microcumaie and thus to be able to predict inad­ vertent changes in weather and cli­ 01 flauls mate produced by present and future activities of man. Some beginnings in The problems are largely concerned this direction are included in the NAS with means for preventing frost, for Panel report. One is an attempt to suppressing evaporation and for re­ assess consequences of the increasing ducing effects of wind. Practical meth­ carbon dioxide content of the atmos­ ods have been in use for long periods phere caused by the burning of fossil of time; there has been limited appli­ fuels. It is estimated that the CO2 con­ cation of modern knowledge of micro- centration in the atmosphere has in­ meteorology to optimize procedures. creased 10 to 15% in this century, Further research on boundary-layer making significant changes in the heat energy and moisture exchange is highly balance. The report states that "the desirable. implications of this upon tropospheric stability cannot be ignored" and that there is need for continuous monitor­ Laroe-scaie MoOiticallon ing of CO2 content and of simulation of CO2 effects "using the most sophis­ 01 cumaie ticated atmospheric models and nu­ merical computers available" to assess The possibilities of making use of in­ the consequences. Another important stabilities in the atmosphere to alter problem is to determine effects of the climate of large regions of the urbanization both on local climate and possible indirect effects which may Control. It should be recognized, how ­ extend over much larger areas. Thus ever, that the 1957 report is concerned far there has been but little research primarily with effects of cloud seed­ on this problem. Effects produced by ing while we are now considering altering the rural landscape (agricul­ weather and climate modification from ture, deforestation, etc.) appear to be a much broader point of view, includ­ less serious. Other problems consid­ ing inadvertent effects of man-made ered in the NAS Panel report are pos­ activities as well as deliberate at­ sible effects of increase in water vapor tempts to modify the weather. content of the stratosphere by super­ Relying mainly on analysis of re­ sonic transport aircraft and of con­ sults of commercial seeding opera­ tamination of the higher atmosphere tions, the Advisory Committee on by exhaust. The report con­ Weather Control reached the follow­ cludes that at present these are not ing conclusions: serious problems. With increasing The statistical procedures em­ technology and population growth, ployed indicated that the seeding of problems associated with inadvertent winter-type storm clouds in moun­ changes in environment will become tainous areas in western United even more important in the future. States produced an average increase in precipitation of 10 to 15 per cent ACCOMPLISHMENTS OF THE from seeded storms with heavy odds that this increase was not the NATIONAL SCIENCE FOUNOATION result of natural variations in the amount of rainfall. PROGRAM In nonmountainous areas, the In order to put the problems of same statistical procedures did not weather modification in perspective detect any increase in precipitation and to see what has been accom­ that could be attributed to cloud plished in the intervening years, it is seeding. This does not mean that of interest to compare our present effects may not have been produced. knowledge with that which existed in The greater variability of rainfall 1957 at the time of the final report of patterns in nonmountainous areas the Advisory Committee on Weather made the techniques less sensitive

43 for picking up small changes which could not be made much more definite might have occurred there than then conclusion (4). when applied to the mountainous The Advisory Committee on regions. Weather Control report recommended No evidence was found in the an increase in research in meteorology evaluation of any project which was and related fields; that the National intended to increase precipitation Science Foundation be the agency that cloud seeding had produced a designated to promote and support detectable negative effect on pre­ such research and to be "a central cipitation. point for the assembly, evaluation, and Available hail frequency data dissemination of information and that were completely inadequate for the development in large numbers of evaluation purposes and no conclu­ highly qualified research scientists in the field is essential. The report also sions as to the effectiveness of hail suppression projects could be emphasized basic research leading to a scientific understanding of weather, reached. with the aim in part of putting cloud Conclusion (1) was later severely seeding on a firmer scientific basis. In criticized as being based on inade­ 1957 there were few professional peo­ quate statistical evidence and lack of pie working on scientific aspects of adequate controls, but present indica­ weather modification. As a result of tions are that it is probably correct. subsequent activities and support of Evidence presented in the NAS Panel the Foundation and other agencies, report suggests that seeding in some there are now involved a number of cases may enhance local precipitation outstanding groups in universities, even in nonmountainous areas by government, and industry. Among the similar amounts. There is some rather universities that have groups engaged tenuous evidence of a shadow zone of in research related to cloud physics decreased precipitation beyond the and weather modification are Arizona, area of local enhancement. Thus con­ Chicago, Colorado State, New Mexico clusions (2) and (3) no longer appear Institute of Mining, Nevada, New to be valid. A current statement con­ York University, Pennsylvania State, cerning the status of hail suppression State University of , and the

44 University of Washington. The Pro­ tending over a five year period at gram of the Illinois State Water Sur­ West Plains, Missouri, indicates a re­ vey is partially supported by the gion of increased radar precipitation State. An outline of the programs of echo extending 30-50 miles downwind various government agencies is given of the seeding line followed by a in this report in the chapter on Fund­ broad region further downwind with ing and Administration Requirements. decreased precipitation. This precipi­ Several industrial organizations such tation pattern was detected by radar as A. D. Little, Inc. have research pro­ echoes and supported in part by rain grams on various aspects of weather gauge data. These data suggest that modification. There are of the order of seeding may produce a growth of 40 to 50 concerns engaged in com­ clouds along the seeding line which mercial seeding operations. sets up a stationary wave-like pertur­ While a great deal has been learned bation extending downstream. In the about the physics of clouds and the region 40-80 miles downstream the precipitation process, because of the air is sinking rather than rising and so extreme complexity of the problem is unfavorable for cloud growth. Thus, there is still far from a scientific un­ the shadow zone of decreased precipi­ derstanding of effects of cloud seed­ tation may result indirectly from a ing and the dynamics of clouds. A dynamical effect rather than from brief review of a few of the major prior rainout of available moisture. projects sponsored in whole or in part (2) For the past ten years, the Kings by the Foundation may be in order: River Conservation District has sup­ (1) One of the most important is ported a cloud seeding program by the University of Chicago "Project Atmospherics, Inc. in the Kings River Whitetop" which has demonstrated Drainage area on the Western slopes the importance of the warm rain of the Sierra Nevada Range in Cali­ coalescence process in many super­ fornia. A grant from the Foundation cooled convective cloud systems provided for additional measurements which formerly were thought to de­ for study of cloud physics and precip­ pend entirely on the Bergeron-Fin­ itation. Recent analysis of the data deisen ice process. A preliminary anal­ indicates an average 6.1 % increase in ysis of a cloud seeding program ex- runoff in the drainage area due to

45 seeding for the period. This supports A great deal has been learned preliminary results of a research from laboratory studies about the nu­ study by Colorado State University in cleation process with AgI as well as the area of Climax, Colorado, and of with other materials; however, much other commercial seeding operations, remains to be done in correlating extending over shorter periods of such laboratory work with effects time, that seeding can give a moderate produced by various practical seeding increase in precipitation in orographic methods. situations. An analysis of these and Considerable progress has been other seeding experiments is included made in studies of clearing of super­ in the NAS Panel report. cooled stratus and fog by seeding. The (3) Project Stormfury, a joint problem of dissipation of supercooled Weather Bureau-Navy project, with fog over airports is now largely one of support from the Foundation, is an design of suitable seeding devices. It attempt to modify tropical clouds and has been suggested that because of perhaps hurricanes by massive seed­ their stability and consequent repro­ ing. The idea here is to enhance cloud ducibility of results, supercooled stra­ buoyancy and thus later cloud dynam­ tus clouds could be used for testing of ics by release of latent heat of fusion. seeding agents. Conclusive results have not yet been Studies are being made of elec­ obtained, although there is consider­ tric fields in clouds, their possible in­ able evidence that clouds can be mod­ fluence on the precipitation mechan­ ified in this way. Howell, in 1960, pre­ ism and of methods for changing the sented data on effects of seeding of electric field patterns as a possible tropical cumuli which indicated en­ technique for modification of clouds. hanced buoyancy and a consequent Much of the activity since 1957, and increase of precipitation. A group at particularly that under Foundation Pennsylvania State University has sponsorship has been aimed at basic been investigating the possibility of scientific understanding. In complex providing positive buoyancy to clouds problems this is a sound if often slow, in the lee wave of mountain systems way of arriving at practical goals. by seeding. With a sufficiently thorough under-

46 standing one should be able to esti­ negut in 1946-47 had repercussions mate both the possibilities and limita­ throughout the world. Within a few tions of various techniques. At the years weather modification activities other extreme are the purely empirical had been initiated in a number of methods of trying various procedures countries. In its Third Annual Report and observing the overall results with­ on Weather Modification for FY 1961 out worrying too much about the de­ the National Science Foundation gave tailed mechanisms of how and why data on work underway in sixteen they occur. In cases where there is a countries.' More than 100 research great deal of natural variability, one stations outside of the United States must rely on sound statistical meth­ were reported as being engaged in ods with adequate controls. Unfortu­ weather modification work. As in the nately many of the empirical studies United States, a major emphasis in of the past for one reason or another most foreign countries has been placed did not yield conclusive results. The upon cloud seeding or other efforts at empirical and basic approaches are rainmaking. Considerable attention in both valuable and complement one some countries has been given to fog another. Empirical discoveries may dissipation and hail suppression, stimulate basic research and lead to while significant basic scientific re­ new understanding. Scientific under­ search programs have been undertaken standing, even though far from com­ in several lands. plete, may suggest new or modified Australia, faced with growing de­ empirical approaches. mands for water, both for agriculture The problems involved in statistical and hydroelectric power, has under­ design of experiments are discussed taken significant programs of basic re­ in this report in the chapter on Sta­ search in cloud physics as well as tistical Aspects of Weather Modifica­ large scale field experiments in cloud tion. seeding. A variety of cloud-seeding experiments has been carried out in ACTIVITIES IN FOREIIIN COUNTRIES Canada by both government and pri­ vate agencies since 1948. France has The achievement in artificial nucle­ established a broad program of scien­ ation by Schaefer, Langmuir and Von- tific research coupled with practical

47 experiments. Ten different organiza­ ural processes of rain formation and tions are engaged in French weather their possible manipulation by artifi­ modification programs; in addition to cial means. An active program of both fundamental research, special interest basic research and empirical studies has been displayed in hail prevention of cloud seeding has been pursued in and fog dispersal. Laboratory research Japan. Some success has been re­ has been featured in , where ported in seeding programs. In 1964 weather modification activities were an International Conference on Cloud late in getting underway. Interest in Physics was held in Japan. Great Britain has also been directed Of particular importance in the almost exclusively at basic research work going on in foreign countries is in cloud physics, cloud dynamics and that being carried forward in the So­ atmospheric electricity. viet Union. Faced with a number of A special concern with the practi­ serious problems created by a hostile cal problem of hail suppression has natural environment affecting the eco­ characterized the weather modifica­ nomic welfare of the country, the So­ tion work in Switzerland. The Federal viet Union has shown an active and Commission for Studying Hail Forma­ intensive interest in the subjects of tion and Hail Prevention, established weather and climate modification. The in 1950, operates three laboratories delegation of the U. S. Weather Bu­ which have contributed significant reau which visited the knowledge to the understanding of in May, 1964, returning a similar visit hail formation and have carried out a to the United States by Soviet scien­ variety of experiments in cloud seed­ tists earlier that year, was particularly ing as a means of prevention. Similar impressed by the broad scope of the concern with urgent national prob­ Soviet program and the large re­ lems has been noted in the develop­ sources of manpower and funds that ment of weather modification work in were being concentrated on weather Israel, where water supplies are of modification and related activities. Al­ paramount importance to the econ­ though actual work is undertaken in omy; a broad program of research and a number of institutes located in vari­ field experimentation has been di­ ous parts of the Soviet Union, and rected at the investigation of the nat- includes activities in both the Arctic

48 and Antarctic, the Soviet activities ap­ tists are convinced the empirical evi­ pear to be well integrated into a na­ dence is sufficient to support their tional program and guided towards the claims of success. Such claims include achievement of objectives directly re­ statements that the dissipation of su­ lated to the economic and social needs percooled fog and low stratus over of the country. airports has now become operational; Among the Soviet Union's theoreti­ that cloud seeding can increase pre­ cal studies, emphasis has been placed cipitation from frontal clouds by upon research in cloud physics at around ten per cent; and that the pos­ numerous centers, as well as upon sibility has been demonstrated of theoretical evaluations of the possi­ greatly decreasing the formation of bilities of climate modification. Indic­ large, damaging hail. Considerable ative of the broad dimensions and benefit has apparently been derived imaginative character of Soviet think­ by Soviet scientists from work done ing have been speculative suggestions in the United States and other coun­ of climate modification by erection of tries as a result of the thorough and major hydraulic structures which extensive program of review and would alter ocean currents, artificially translation of scientific literature—an inducing changes in snow cover, pro­ aspect of research some American sci­ ducing changes in by entists believe could well be expanded seeding, and altering the surface to in this country. induce lifting or subsidence of air. The resume given above of some of One of the most spectacular is the the major weather modification activ­ suggestion of damming the Bearing ities in foreign countries is by no Straits. means a complete inventory. Other Field experiments have concen­ work is being initiated and carried trated upon three areas of common forward in several other countries. concern to many other countries: dis­ The wide distribution of activity in sipation of fog and low stratus clouds, this field throughout the world is in particularly over airports; suppres­ one sense a reflection of the essen­ sion of hail; and rainmaking. While tially international character of sci­ statistical tests have generally not ence. It is also an indication of the been undertaken, many Soviet scien- growing realization by scientists, and

49 by governments, that the possibility of weather and climate modification Hydrologic Cycle may have profound repercussions upon the future economic and social The words Weather Modification have come, through usage, to mean welfare of their countries. the conscious intervention by man in the precipitation process; either its augmentation or reduction and ulti­ PERSPECTIVES FOR RESEARCH mately its control. In this view atten­ tion is centered on the atmosphere. It is recognized that several inter­ But weather is only a link in the related branches of earth science must hydrologic cycle in which water, be developed as a foundation for the through various energy exchanges, is technology of environmental control. distilled from the oceans or transpired from the ground water table into the These include study of the mechan­ atmosphere, is stored in the atmos­ isms and energy balances involved in phere for a time, and eventually re­ the hydrologic cycle, development of turned to earth in another place. further understanding of the dynamics In principle, effective practice of of climate through atmospheric mod­ weather and climate modification may eling and computational experiments consist of activities which produce alterations at any point in the hydro­ including weather prediction, broad­ logic cycle that could conceivably lead ening both field and laboratory re­ to control of persistent or momentary search in cloud physics and dynamics, extremes. Since the global water cycle and a thorough examination of the is a closed but multiply-connected non-atmospheric mechanisms, such as loop (much like the cardiovascular modification of the surface character­ system) the consequences or effective­ ness of intervention may either be istics of the land and sea, which might "healed" by self-regulatory processes conceivably alter weather or climate. which give the hydrological system Each of these will be discussed in its stability, or lead to systematic turn. change.

50 The problem of weather and climate modification, then, requires sufficiently Dynamics 01 Climale detailed understanding of the energy transformations of the hydrologic In the various aspects of the weather modification problem thought has been cycle to know where, how, when, and centered around the issues of water with what intensity man's interven­ resources particularly in those areas tion in the natural system may pro­ where there is a shortage of supply. duce significant alterations. Effective This is a natural concern because it pursuit of this understanding will re­ is one ultimate goal of the weather quire the concerted knowledge and and climate modification concept to skills of geologists, hydrologists, regulate, if not increase, the availabil­ ity of potable water for the uses of oceanographers, meteorologists, engi­ mankind. In consideration of this goal, neers, and the close support of those it is necessary to think not of times versed in applied physics, mathe­ and localities where the need for matics, ecology, and chemistry. As water is most sorely felt, but of the yet this breadth of enterprise has dynamics of climate over the whole neither been reached nor contem­ earth in which the dry areas have plated. context. Since precipitation in the free air is In the present state of knowledge associated with the rise and adiabatic atmospheric intervention seems to cooling of moist air, the processes to offer a promising point at which to be encouraged must be those which exert an influence upon the hydro­ will induce rising motion, especially logic cycle in the interests of man­ of maritime air over regions presently kind. However, as knowledge is ad­ deficient in rainfall. Rising air occurs in three principal situations: in cumu­ vanced in other areas of the earth lus convection (micro to macro scale), sciences, particularly in oceanogra­ in orographic lifting (meso to macro phy, it is possible that other and per­ scale) and in frontal lifting (macro haps even more promising alternatives scale). Once initiated, lifting may be may come to light. encouraged by energy releases asso-

51 ciated with phase changes in the water the belt in each hemisphere, burden of the atmosphere. Lifting may sinking predominates and there is a also be encouraged by physical or consequent excess of evaporation over thermal topographic influences on the precipitation owing to the adiabatic earth's surface. heating of the descending air. In high In regions where an excess of pre­ middle latitudes frontal lifting is the cipitation exists it might also be de­ predominant mechanism promoting sirable to suppress rising motions of the development of stratiform clouds air. The mechanisms governing sink­ from which precipitation may occur. ing motions are not yet clear and must Local anomalies in this general pat­ be understood before regional weather tern are developed by orographic in­ modification can be contemplated. fluences and surface effects. Effective Rising and sinking motions in the weather regulation would rearrange general circulation of the atmosphere the geographic limits within which tend to be arranged in zonal patterns, these statistically predominant zonal hence climates of the earth also tend configurations of rainfall and evapora­ to be developed in zones. The non- tion now occur. zonal irregularities in the arrangement A problem of this magnitude re­ of climatic belts on the earth are found quires study of the susceptibility of in the transition regions between land the atmosphere to change by system­ and sea, because heating air flow is atic influences. It is already well known predominantly zonal while the distri­ that the atmosphere responds as a bution of land is more nearly merid­ whole to disturbances within any part ional. of it. It is also known that the atmos­ In the atmosphere, as it is now con­ phere exhibits a kind of statistical stituted, there are belts of rising and stability. If it did not, the subject of sinking air the emerge with statistical climatology could not be pursued. One significance. In the intertropical con­ has, therefore, to learn through an in­ vergence near the geographic equator tensive series of computer simulation rising motions occur and cumulus con­ experiments and quantitative labora­ vection is the principal mechanism tory investigations with rotating mod­ for the release of precipitation. In the els where, how forcefully and how subtropical zones near 300 latitude, often the atmosphere must be dis-

52 turbed to change the statistics of cli­ quence of weak but systematic matology. The question at this point interactions which may easily be should be addressed to a study of disrupted once we learn what the changes of all kinds. Once the effects critically participating processes and energy requirements for interven­ are?* tion are known from laboratory and A program of this kind is bound to numerical studies, it would then be involve a considerable expansion of possible to select certain changes as effort and facilities. For example, the a basis for field experimentation. It computational effort required is would also be known how massive roughly two orders of magnitude such undertakings in the field might greater than that possible with the have to be to produce effects that largest machine now in existence. The emerge clearly above the normal levels suitable equipment for laboratory re­ of atmospheric variability. search in rotating models might also One would hope that model ex­ cause an expansion of effort by a fac­ periments will divulge the type of tor of two or three over the present instabilities that can be seized upon level. Still, the hope would be that to swing a climate regime in a this kind of undertaking could be particular direction. If it becomes accomplished with only moderately evident that the atmosphere only marginally sustains a particular phe­ increased resources of manpower, nomenon; for example, if it appears through student training and the at­ that hurricanes are not an essential traction of foreign scientists into this element of the general circulation, sphere of activity. Since the atmos­ then perhaps one can accomplish pheric, oceanographic and geologic the corresponding heat flux entirely properties of the whole earth are to by a related phenomenon which is be considered, there would be a nat­ more prevalent, i.e. weakly organ­ ural basis for international coopera­ ized convection. Speculating on a tion. much larger time scale: is the oc­ currence of an ice age or the forma­ * Smagorinsky, J. 1964 statement at the National Science Foundation Interagency tion of a large desert an inexorable Conference on Weather Modification, Wash­ necessity or are they the conse- ington, D. C., 5-6 November 1965.

53 becoming well established. And with Prediction their continued development, comput­ ers may be expected to have reached Useful as control might be in the necessary levels of storage capac­ weather management, prediction can ity and speed within a decade. Having serve an almost equally valuable social this much so close at hand it would and economic function. Accurate pre­ seem appropriate that the scientific diction is possible only when there is and engineering aspects of a global ob­ virtually complete physical under­ servation network be given immediate standing of the processes interacting attention. to produce change. Prediction also requires a very complete description of initial conditions; which is to say cloud Physics and Dynamics it will soon be necessary to establish a global network of observatories The problem of weather and climate across the land and sea areas of the modification is basically centered on whole earth to fill out the significance finding procedures by which man may of satellite reports. Steps toward this intervene with relatively low expendi­ end are already being taken in con­ tures of power to achieve detectable nection with the World Weather alterations of the atmospheric regi­ Watch, but consideration of the cor­ men, and of coupling that power to responding networks needed to deter­ the atmosphere in efficient ways. In mine the fluxes of heat, mass and present cloud seeding practices a point momentum within the oceans and be­ or line source of material is diffused tween the oceans and atmosphere is into a significantly large volume of air not yet so far advanced. The related by atmospheric turbulence. The dis­ technological problems of sensing, turbance produced in the air feeds on telemetry and maintenance of field the energy of phase changes in the equipment in a global network have water substance in the atmosphere, not even been defined. However, were and with consequent conversions of surface and upper air observations to latent to sensible heat, presumably be available on a global basis the alters the buoyancy of air parcels to means for their analysis are even now excite or amplify vertical motion and

54 the further exchange of sensible and effects of intervention might be ampli­ latent heat until the point of detect­ fied enough to be detectable beyond able returns has been passed. the present screen of statistics, and at Some recent experiments suggest the same time, means developed to that beyond the site where precipita­ control the area of influence. tion is excited by silver iodide nuclea­ In parallel with this thought, there tion there is a "rain shadow" which is, as yet, very little understanding of in itself suggests that wave-like effects the natural processes by which water are involved. This finding may have vapor condenses to form cloud drop­ revealed a useful principle. lets, of how such droplets coalesce to It is a relatively common observa­ form precipitable entities, or how the tion that there are many kinds of quasi- additions of seeding nuclei alter the periodic wave motions in the atmos­ natural process. We suggest that along phere. Cloud streets are often seen, with that necessary study it may be lenticular clouds stand in trains in the well to acknowledge that the earth lee of mountains, long cumulus trains supports a pronounced electric poten­ develop downwind of ocean islands, tial gradient which is changed in cer­ cyclonic storms develop in families tain storm conditions. Since it is well along fronts, and fronts themselves known that the coalescence of spray­ have conspicuously wave-like charac­ ing jets is markedly influenced by the teristics. presence of an electric field far weaker As a beginning it would seem de­ than many of these, it seems only rea­ sirable that cloud seeding experiments sonable to encourage deeper study of be extended to include study of the plume of dynamical consequences electrical relationships in the atmos­ downwind, with an eye to the possi­ phere. Causality is not the question, bility that resonances might be ex­ but rather the interdependence or co­ cited if the phase of successive inter­ existence of electric fields and coales­ ventions were correctly placed in cence phenomena that needs exami­ space and time, and conversely that nation, with the prospect that through damping could be managed if the deliberate atmospheric electrification points of excitation were deliberately some control of the coalescence proc­ placed out of phase. In this way the ess may be exercised.

55 The field of cloud physics and dy­ monsoonal winds and on all sub­ namics must be developed far beyond tropical continents, govern the curva­ its present state if weather and climate tures of the polar fronts and the modification is to become a matter of courses of both tropical and extra- practical concern. The questions of tropical cyclones. The oceans provide droplet formation and growth of pre­ the atmosphere with most of its mois­ cipitable elements in the dynamics of ture, and because of their large thermal clouds need examination on a broader inertia tend to hold fast the maritime base than the present level of effort centers of high and low surface pres­ or varieties of research can supply. sure, and thus fix the patterns of Achievement of this state of under­ world climate. standing will require the best efforts The natural scale of oceanic fea­ of those versed in surface physics and tures is large indeed, but through chemistry in addition to physical and liquid-filled rotating models many of dynamical meterology and possibly their physical aspects can be studied also in acoustics, electrostatics and in the laboratory and the effects of dynamics, and high energy optics. As deliberate modifications assessed. For funding is increased for weather and example, the consequences to the climate modification early priorities of ocean circulation to be expected if the expenditure should be accorded the planetary wind field were to be al­ development of cloud physics and tered or the effects of barriers placed dynamics as a necessary basis for across narrow gaps (such as the Ber­ sound technology. ing, Florida, or Gibraltar Straits) can be examined in rotating models. Simi­ lar studies can be made for the land, Non-Almospheric Inlervenflon such as the utter removal of all moun­ tains from the earth or adding the The atmosphere is underlain by solid topography of past continental gla­ earth and broad expanses of sea water ciers, but perhaps better in these cases and responds to their influences. The with numerical models. Both of these effects on the atmosphere of ­ investigative techniques have been ally differential heating and cooling brought to useful levels of refinement of the solid earth and oceans produce in the past two decades.

56 Granting a present capability to with a curtain of small bubbles. If the make reasonable estimates of the entrained water is lifted isothermally physical consequences of large scale it will tend to sink again; but if the alterations of the land and sea, the process is quasi-diabatic a mixture of difficult part of the question of non- cool, somewhat fresher water can be atmospheric intervention in climate made to remain on the surface and and weather is shifted to that of field to move off with the surface current. methods, power requirements and con­ The effect on the atmosphere of trols; and of the sites for possibly de­ such alterations of the surface tem­ sirable surface alterations. In this perature of even great torrents like connection the ocean offers some the Gulf Stream or Kuroshio might be especially interesting possibilities. small at first because, though swift, It is now well established that the these currents are very narrow. Still, ocean is characteristically in a state in time, the wind-driven Ekman trans­ of stable density stratification. While port would carry the modified surface density increases with depth; in the layer seaward and generalize the in­ and subtropics the surface fluence of surface cooling. water tends to be warm and while In Arctic waters bubble sheets have the subsurface layers grow colder and been proposed to keep navigable wa­ somewhat fresher with depth. The ters clear of ice. But in low and mid­ transition zone between these two dle latitudes surface warming is more principal water types is the main difficult to contrive. For the North thermocline which is found at a depth Atlantic there is a possible procedure of about one-hundred meters in the in the fenestration of the Panamanian tropics and some several hundred Isthmus. meters in middle latitudes. Thus to These influences depend on the cool the surface of the ocean it is thermal stability of the oceans. But the necessary only to bring the cold water salt burden of the ocean is unstably below the main thermocline upward stratified. The warmth of the surface through the relatively short distance water permits the uppermost layers to the surface. to be saltier than those at depth. In This might be done with some effi­ consequence a parcel of warm, salt ciency by infusing the cold layers surface water carried downward and

57 allowed to lose heat to its surround­ of weather and climate modification ings, will continue to lose buoyancy must be based on four fundamental and sink. Conversely, a parcel of cold, pursuits: relatively fresh deep water once assessment and development started upward, will continue to gain of an understanding of buoyancy and rise. Such parcels can­ natural climatic change. not be large, because of the heat assesment of the extent and transfer requirements, but there is development of the under­ nothing, in theory, to prevent them standing of inadvertent modi­ from being so numerous that their fications of weather and cli­ net affect on vertical mixing might be mate. of geophysical significance. improvement of the process Finally it may be worth recalling of weather prediction as a that the surface of the ocean receives social benefit and as proof of more than two-thirds of the world's scientific understanding of at­ supply of precipitation and dew, and mospheric behavior, and is the ultimate reservoir of not only development of means for river discharges but glacial melt water. deliberate intervention in at­ All of this water is fresh but presently mospheric processes for irrecoverable. Still more fresh water weather and climate control substance lies bound as ice. Ice is re­ and evaluation of their con­ coverable. Should the need grow so sequences. desperate or economical means of transportation be devised, ice and its As steps toward these attainments the melt water provide an as yet unex­ Commission recommends that the fol­ ploited resource. lowing enterprises be fostered: Examination of the routes, rates and reservoirs of water sub­ CONCLUSIONS ANO stance and energy exchanges in RECOMMENOATIONS all aspects of the hydrologic cycle. The Commission concludes that Investigation by numerical lab­ sound progress toward the technology oratory and field experiments of

58 the dynamics of climate as a Study of the effects of large basic study for weather modifi­ scale surface modification by cation technology. numerical and laboratory models Advancement of weather pre­ of the oceanic and atmospheric diction as a proof of under­ general circulation, and of prac­ standing, including support of tical means for surface modifica­ this effort by the establishment tion of the land and sea. of a global weather observation network. Study of the radiative effects of Broadening of of changes in the atmospheric com­ cloud physics and dynamics in position and alteration of its the laboratory and field, with at­ transparency that urban growth tention to wave phenomena and and new forms of industry, an evaluation of electrical influ­ transportation or land use may ences. evoke.

59 extinction a natural species popula­ INTRODUCTION tion. Contrary to J. P. Miller's whim­ RIOLOOICAL sey biologists cannot limit themselves Man is an organism directly de­ to "proving that what must be done pendent on other organisms for many for political reasons is biologically ASPECIS OF of his materials. He also struggles safe for the human race." with other organisms, most of them quite small, that prey upon him, eat WEAVER his food, or otherwise challenge his MEANS Of PREOICTINO existence. Anything that has a gen­ CONSEQUENCES Of MODIRCATION eral and significant effect upon plants and animals, making some more abun­ WEATHER MODIFICATION dant, others less so, is of primary con­ cern to mankind, for it strikes at the It must be recognized that the pres­ very basis of human existence. ent state of knowledge places uncom­ Changes in weathr and climate may fortable limits on the prediction of the be expected to have such effects. It biological consequences of modifying follows that any program of weather the weather. Several lines of investi­ modification must give serious atten­ gation can be used, however, to pro­ tion to adverse as well as beneficial vide information. biological aspects. As Lynton CaldweIl observed in the The Study Committee of the Ecological Society of America was asked by the Na­ Yale Review, "Biopolitics: Science, tional Science Foundation to undertake a Ethics and Public Policy," Vol. LIV: study of the present status of knowledge of 1-16, 1964, biologists are with increas­ effects of weather and climate on plants and animals and to recommend the type of bio­ ing frequency finding themselves at logical program that should be associated variance with other segments of so­ with research in weather modification. The ciety on matters of public policy. Ex­ study was made by an Ad Hoc Weather Working Group, chaired by Daniel A. Liv­ amples range from questions concern­ ingstone, Duke University, and is reported ing how much radioactive or pesti­ in a paper entitled "Biological Aspects of cidal materials should be permitted Weather Modification," to be published in loose in the environment to the rela­ the March, 1966 issue of the Bulletin of the Ecological Society of America. See the Ap­ tive merits of trying to preserve from pendix.

60 These will be discussed, indicating speckled trout, the loblolly pine, and the special advantages and deficien­ a number of crop plants, that have cies of each avenue of study. been investigated at all exhaustively. This laboratory approach has sev- Lalioralory SIUMOS eral deficiencies as a means for pre- dicting the field results of weather A single organism or a small number modification. The response to weather of the same species can be subjected may be very different for organisms of to controlled experimental conditions the same species collected in different in the laboratory, and the response parts of its range. Because of genetic to various elements of climate, such changes, an organism taken directly as temperature, moisture and light, systematically investigated. This from the field and grown under con­ basically straightforward approach is trolled environmental conditions in not without complications. If, for ex­ the laboratory may react differently ample, one seeks to investigate the from one which is the result of sev ­ effect of temperature upon the growth eral generations of genetic selection of a plant species, it is not sufficient pressure in a large population growing to measure the plant's growth at a under similar conditions. The most variety of constant . serious deficiency of this approach is Some plants are more influenced by that it treats species in isolation. In the daytime temperature, some by the nature, very few organisms are lim­ night temperature, while others thrive ited in range by direct climatic condi­ best under conditions that are speci­ tions that exceed their physiological fied by the difference between day and night temperature. The responses limits, but rather by competition with to light are similarly complicated. For other species that are better able to reasons such as these, the experimen­ cope with the prevailing conditions. tal approach has been applied to a Such considerations limit the applic­ very small fraction of the known spe­ ability of results obtained in the lab­ cies of plants and animals, and there oratory for predicting results of are only a handful, such as man, the weather modification in the field.

61 are safest when they are most general. ROCOP93 Of AnnUal Variation A change from grassland to savanna under increased rainfall can be pre­ The results of year-to-year varia­ dicted much more securely than the tions in the natural weather on biolog­ species composition of the savanna or ical phenomena can be used as a the exact amount of rainfall increase basis for predicting the results of sim­ that would be required to effect the ilar perturbations produced by man. change. This method is suitable for predicting the effects of short-term weather mod­ Study of the fossil record has also ifications that are similar in nature provided a wealth of information and extend to natural climatic fluctu­ about the biological effects of a par­ ations. With these limitations, it can ticular set of climatic changes, those be used to predict the offsets of ticular set of climatic changes, those weather modification upon a few associated with glacial and intergla­ well-studied crop plants of great eco­ cial conditions, and a substantial body nomic importance, and a few well- changes in the more remote proglacial studied insect or microscopic pests. periods. Use of these data is hampered by lack of independent information about the actual physical changes in DloeograpklcaI and climate that were involved, so that much investigation of these changes Fainecapical ROCONS consists of an attempt to infer cli­ matic changes from the biological evi­ furnishes another use­ dence, rather than determining the ful source of information about the way in which organisms have been in­ relation of organisms to climatic fac­ tors. Correlations between the distri­ fluenced by climate. Nevertheless, the bution of organisms and climatic fossil record gives the only available conditions suggest that climate has a information about the biological re- primary role in determining these dis­ suits of a major climatic change on a tributions. The predictions that can global scale, and for this reason it is be made from biogeographical data particularly valuable.

62 any statements concerning effects, the monnorine 01 Selectefi sample areas must be well replicated. Communities Monitoring experiments will be diffi­ cult to set up. It is patently impossible Experimental plans for weather to study every species in a rigorous modification should insure a maxi­ way, and it is quite possible that ran­ mum yield of biological data on the domly selected species will turn out nature of effects. This requires both not to be those most useful for the the establishment of comparable con­ study. Some guiding principles might trol areas outside the areas of modifi­ include a mixture of the following cation and pre-modification monitor­ attacks: 1. A well-replicated series of ing of sample areas in both the reasonably detailed examinations of control and modified areas. Natural communities would be selected for selected natural biological arrays at study in an area in which weather is transition areas joining biological to be modified and permanent experi­ communities which are apt to show mental plots established in them. Well changes with the predicted shifts. 2. before weather modification, the biota Examination of a range of agricultural on these plots should be inventoried and other artificial ecosystems for in detail and mapped or photographed. changes in disease, pests, yields, har­ Such studies should precede modifica­ tion by a long enough period to col­ vest dates, etc. 3. Studies of relative lect data on the normal fluctuations of changes in population sizes, reproduc­ the communities and populations. The tive success, etc., of a selection of plots would be re-studied during and more easily studied organisms within after periods of weather modification blocks of homogeneous natural com­ to determine what species expanded munities away from transition areas. their populations and what species Reasonable controls are essential; lost ground; what species disappeared from the community and what new hence, in order to be effective, moni­ species entered. Since proper evalua­ toring must be done outside these tions will require confidence limits for areas in comparable sites.

63 tively invariant even when indepen­ COMPHIP SIMU18900 SIUMBS dent variables are run through a wide range of values on the computer. Also, Computer simulation studies pro­ it is desirable to see if certain strate­ vide a method for predicting biolog­ gies are grossly uneconomical if ap­ ical effects of weather modification. plied under certain circumstances. Two quite different approaches to The logic of the simulation ap­ computer studies are available. A proach is bolstered by studies on such model that approximates reality very insect pests as the spruce bud worm. closely cannot be made at present for Through the longterm concerted ef­ any given area because of the lack of fort of large teams of investigators, it data. Hence, computer experimenta­ has been possible to construct models tion may need to be postponed for 5 sufficiently close to reality to have to 10 years until the requisite data on practical use in predicting outbreaks the location in question are available. and in choosing control strategies. An alternative is to proceed immedi­ Outbreaks of plant diseases are prob­ ately to construction of a simulation ably also capable of being studied model, using data on the same, or re­ with the same methods. lated organisms from places other The principal motivation for com­ than the proposed site for the weather puter simulation is cost. It is enor­ modification experiment. In so doing mously cheaper to run experiments the following question must be asked: on the computer than to try out a "How would an ecosystem similar to great variety of weather modification that which presently exists at the site experiments in nature and observe the for the weather modification experi­ results. Both the cost of the experi­ ment be altered if one modified typ­ ment and the losses due to the experi­ ical sequences of weather data within ment by using simulation as a supple­ ranges of values known to be realis­ ment to an actual experimental pro­ tic?" In general, the type of thing to gram are saved. The basic structure of determine with simulation studies is the computer simulation program will whether certain combinations of strat­ be a set of functional relationships egies or strategies used singly, show which mimic the dynamic properties certain broad features that are rela- of all relationships between and within

[] soils, plants, animals, site factors and weather, with respect to changes both eenemi Enecis in variables through time and in dis­ Paleoecological studies in many of persal of entities through space with the climatic regions of the earth indi­ the of time. cate that temperature modification corresponding to an annual average difference of 3 ° to 4°F. brings notice­ PREDICTED BIOLOGICAL RESPONSES able alterations in population levels of many resident plants and animals and OF WEATHER MODIFICATION the appearance and disappearance of some other species. In many cases, An ecological system consisting of however, the broad kind of vegeta­ agricultural fields is well enough un­ tion, such as hardwood forest or grassland, still remains. A change in derstood that effects of specified temperature of twice this magnitude weather and climate modifications brings replacement of many species can be predicted with some assurance. by others, wide changes in population In a more complex system consisting levels of species present at both ex­ of many more species of interacting tremes, and in many cases replace­ plants and animals, the complexity is ment of one major kind of community by another. so great that it is not possible to make From long-term studies of the detailed quantitative predictions. American prairie, it may be predicted However, certain general effects can that the direct effect of moderate be outlined. In illustrating this, con­ changes in rainfall on the biological sider temperature changes up to sev­ communities as a whole may be ex­ eral degrees Fahrenheit and rainfall pected to be relatively slight, mostly involving shifts in sites occupied by changes, principally increases, of species. The changes will probably be some tens of percent of the present slow unless large areas become defoli­ annual average on reasonably well- ated or killed through the anticipated watered lands. increase in certain pests or the corn-

65 munity is otherwise seriously dis­ productivity if all other conditions turbed. However, changes in rainfall remained the same, because the in­ or temperature which are of sufficient creased reliability of the return would magnitude to have general usefulness permit more efficient farming opera­ seem likely to be of sufficent magni­ tions. tude to produce substantial disturb­ ances in natural communities. Most studies showing correlations species Extinction and Disruption between weather conditions and changes in the abundance of one or 01 Nampai communines more species of organisms have also brought out the fact that it is the With the growth of human popula­ weather during a few critical months tion and its spread over the land in that is important, rather than the aver­ the United States, native species are age conditions over the years. Thus, increasingly confined to small sanctu­ for many species, a minor increase in aries—parks, wildlife refuges, and the average annual precipitation could mountain ranges. These are islands mean either enormous increases or surrounded by oceans of land inten­ great mortality, provided that the sively occupied by man, and it is not extra rain fell during a period that was generally possible for wild species to critical for survival or reproductive migrate across the rural and suburban success. oceans from one island to another, to survive climatic change. If climate is so changed that a species is no longer increase in CPOP PrOdUCHYR able to survive in a given natural area, that species cannot migrate but must It seems quite clear that an increase become extinct there. Extinction of in rainfall would result in an increase species implies reduction in species- in production of cultivated crops over diversity, the richness of natural com­ a large part of the earth. Even a reduc­ munities in numbers of species. Re­ tion in variance in rainfall, or the duced species-diversity and shifts in ability to control its seasonal distri­ population distributions resulting bution, would lead to an increase in from weather and climate modifica-

66 tion would combine to reduce the sta­ between abundance and weather con- bility of natural communities. ditions. The number of cases is suffi- There are differences of opinion ciently impressive to permit the con- among biologists about the extent to clusion that changes in weather from which a particular modification would year to year do lead to changes in the affect the stability of natural commu­ abundance of certain species, and in nities. Most would expect an appre­ some instances lead to changes in ciable disturbance to result from a their distributions. It seems probable modification great enough to be useful that many, if not all, of these species economically. Some species would be­ will be highly destructive to agricul­ come more vulnerable to outbreaks tural enterprises or to the natural of pests and some natural preserves vegetation, or to both. Unfortunately, would become less aesthetically at­ too little is known of the mechanisms tractive and less valuable for research of population control of most species purposes. The economic consequences for us to be able to predict which would be felt in communities that are species will become serious pests used for grazing or lumbering. under altered weather conditions. It is It is likely that the changes pro­ also true that some likely changes in duced by weather and climate modi­ weather would result in abnormally fication in insular remnants of natural low populations of other species. Well communities will be consistently un­ known examples of species for which favorable ones. Immigration of the high rainfall is deleterious are the normal respondent species is subject chinch bug, Blissus leucoptorus, and to interference. In more continuous the pale western cutworm, Porosogro­ areas the shifts would result in more tis orthogonia. It is likely, however, temporary but not necessarily incon­ that weather modification will lead to sequential instability. large agricultural losses due to the increases induced in populations of some terrestrial pest species, and that ProaHIe Increase In crop Pests these losses will not be compensated by perhaps equally frequent reduc­ For insect pests, there exist numer­ tions in the populations of other ous studies indicating relationships species.

67 eases, some of them carried by arthro­ Pmhahie increase pod vectors, such as bubonic plague. in Disease VOCIOPS It is not believed that an epidemic of plague would necessarily result from One class of organisms, the ones weather modifications, but the possi­ that are borne by arthropod vectors bility exists that there might be some and cause serious diseases in man and sort of weather modification which his domestic animals, are deserving of would cause it to occur. There is a special attention. Although there is substantial reservoir of sylvatic plague some reason to believe that other dis­ in the United States. eases may be influenced by weather Many bacterial and fungal diseases conditions as well, it is clearly estab­ of crops are also known to be highly lished that many of those with arthro­ responsive to weather. Increased rain­ pod intermediate hosts are dependent upon weather conditions. One can pre­ fall, more humidity, warmer dict that weather modification would or cooler temperatures would all have produce a shift in the pattern of vec­ effects on plant pathogens. Not enough tor-borne diseases. In any plan to is known to predict the significance modify the weather, disease must be of the almost certain changes. given very serious consideration, for it may be of greater economic impor­ tance than the circumstances which Effect 01 Possible Rain-Sbagows stimulated interest in weather modi­ fication. While an increase in precipitation The outbreak of many insect pests has predictable results among which seems to be triggered by a rather un­ both favorable and unfavorable effects usual meteorological situation in one can be expected, and which might off ­ restricted part of the range. The popu­ lation builds up first in that local cen­ set each other to some extent, a con­ ter and spreads out in all directions in comitant decrease in precipitation in the form of a wave. This pattern is another area has no beneficial effects similar to that of many human dis- to offset the obvious damage.

68 in these disruptions cannot be pre­ CONCLUSIONS AND dicted, nor can their cost. For the present, weather and RECOMMENDATIONS OF THE climate modification should be re­ ECOLOOICAL SOCIETY stricted to local small-scale operations. Larger scale operations, such as WORKING 6ROUP an attempt to increase the rainfall of any substantial part of this country, Living things are adapted to the should not be undertaken, from a bio­ weather that actually prevails, and logical point of view, in the present any change in that weather will be state of knowledge. generally deleterious to them. All weather modification experi­ The largest credit item for ments of a scale large enough to have weather modification is likely to be an important biological consequences, increase in primary production of the such as those currently envisioned for drier parts of the land surface through the Upper Colorado Basin, should be improvements in rainfall. Even the preceded and accompanied by careful ability to control seasonal distribution ecological monitoring and computer of rainfall would lead to more efficient simulation studies. Manipulating the farming operations. Realization of the weather to obtain a net benefit will potential increase in production would demand much better understanding of depend upon being able to modify the the interactions of weather, climate rainfall without major pest outbreaks and organisms than now available. and extinction and disruption of nat­ Adequate understanding of the ural communities. It is not certain that interrelationship of weather, climate this would be possible. and ecology will demand a very ex­ The largest weather modification pensive long-term research program. debit item is likely to spring from the Present resources of ecologically ­ decreased stability of communities, trained investigators are inadequate which would manifest itself in an in­ to cope with these problems. crease in pests, weeds, and pathogens. The Working Group of the Ecologi- The identity of the species involved cal Society of America, which pro-

69 vided background material for the operations on the scale mentioned are Commission, was concerned primarily likely, however, to have far reaching with modifications of weather sys­ biological consequences as pointed tems ranging from a single cloud to out in the previous sections, and some an extratropical cyclonic storm. The of the biological changes would not Working Group stated that short-term be reversible. This advisory group recommended that repeated and long modifications of weather of a magni­ term modifications of weather not be tude similar to the fluctuations in attempted without prior careful and nature are least likely to have danger­ well planned monitoring or computer ous unforeseen consequences. If un­ simulation studies of the biological desirable results appear, the modifica­ consequences of particular kinds of tions can be discontinued. Repeated weather modification.

70 This analysis, however, has not com­ STATISTICAL THE PRESENT SITUTION pletely dispelled the skepticism con­ cerning evidence obtained as a by- Problems of statistical methodology product of operational activities. The ASPECTS arise when there is a controversy as question is not whether to use statis­ to interpretation of data already ac­ tical but how to use it in the early cumulated or as to ways of going design and subsequent analysis of OF about acquiring additional informa­ experiments. tion. That such controversy should WEATHER arise in connection with weather modification experiments is hardly THE CONFERENCES ON surprising. MODIFICATION Almost twenty years after the orig­ STATISTICAL METHOOOLOBY inal experiments in cloud seeding, conclusive evidence acceptable to the The National Science Foundation scientific community as to ground sponsored three conferences for the precipitation effects of cloud seeding This chapter draws upon materials as­ is still lacking. The basic issue of the sembled by Prof. Byron W. Brown, Jr. of effectiveness of seeding non-oro­ the University of Minnesota as a result of three conferences held under the auspices graphic cumulus clouds has been sub­ of a National Science Foundation grant. ject to sharp changes of opinion and These conferences brought together scien­ to conflicting evaluation in recent tists actively engaged in weather modifica­ tion research and statisticians experienced months. In the absence of conclusive in the planning of scientific experiments. guidance from scientific experimental Also, acknowledgement is made to unpub­ data, the National Academy of Sci­ lished memoranda and letters by Dr. Julien Bigelow (Institute for Advanced Study), Pro­ ences Panel on Weather and Climate fessor William Kruskal (The University of Modification embarked on an inten­ Chicago), Dr. Theodore Harris (Rand Corpo­ sive statistical study of data from ration), Professor Jerzy Neyman and Dr. Elizabeth Scott (University of , commercial projects. This analysis Berkeley), Mr. Glenn Brier and Dr. Joanne concluded with the impressively posi­ Simpson (USWB) and many other statisti­ tive findings on the efficacy of cloud cians and scientists who participated in these conferences. The list of participants in seeding—a position supported in gen­ these conferences appears as Footnote 1 to eral by the available scientific data. this chapter.

71 purpose of bringing together statisti­ tending the meeting to ask questions, cians and scientists interested in the comment on the presentations, and be statistical aspects of weather modi­ questioned in turn. fication experiments. The first confer­ ence, in January, 1965, brought to­ gether scientists participating in many CONFERENCE FINOINOS field experiments throughout the country. These scientists briefly re­ A number of results have come viewed these programs and plans, from these conferences. with special reference to the statisti­ Field experiments are a neces­ cal problems that have been encoun­ sary part of a research program on tered. The statisticians present had an weather modification by cloud seed­ opportunity to comment on these brief ing. Laboratory experiments of the reviews and on their own experiences scope and refinement necessary to in this area. predict field results are not economi­ The second conference, in April, cally feasible and, further, the theory 1965, focused on Project Stormfury. necessary for laboratory simulation of The project director and the statistical the mechanisms of free air precipita­ consultants for this project presented tion has not been developed. Practical the results of past work, the criticism effects must be estimated in the field. of this work, and the plans for the The number of variables in­ summer of 1965. The statisticians and volved and the lack of knowledge weather modification scientists used about the details of atmospheric pro­ this project as the point of departure cesses make weather modification for discussion of general questions of field experiments difficult to plan and design and evaluation of experiments. evaluate. Careful use of the best tech­ At the third conference, in June, niques in scientific methodology is re­ 1965, scientists in the Bureau of Rec­ quired. This entails the cooperation of lamation, and in projects sponsored scientists who can frame the hypoth­ by the Bureau, reported on a number eses and specify some of the impor­ of Bureau projects and related work. tant variables, statisticians who can Again there was an opportunity for suggest ways of using this information other scientists and statisticians at- to gain precision, mathematicians, in-

72 strumentation specialists, engineers, neers interested in the atmospheric hydrologists and others. sciences. This statistical training Many of the investigators in this should include the principles of field field do not have formal training in experimentation—nature of statistical statistical methodology. A few do not models, random allocation of treat­ realize this methodology is essential ments, local control, replication and to their work. Others realize the use­ blind evaluation—as well as the clas­ fulness of statistical methodology for sical techniques of design and data planning and evaluation, but do not analysis. have adequate statistical support for Steps should be taken to assure their programs. that government-supported research Planing and evaluation of weath­ utilizes statistical principles in plan­ er modification experiments present ning and analysis. It is desirable that some special problems in statistical statisticians participate with meteor­ methodology. These problems must ologists, and other scientists, in the be resolved or circumvented if re­ evaluation of proposals for govern­ search in weather modification is to ment-supported research. benefit from the use of statistical Statistical advice for scientists principles. Statistical research is in this field should be made available needed in questions such as the fol­ through (i) sponsorship of conferences lowing: optimal spacing of rain gages, (e.g., the Foundation series) where optimal use of rain gage data, effects plans for new projects can be pre­ of crystals contaminating unseeded sented for criticism; (ii) use of statis­ areas, best ways of taking advantage ticians as members of the committees of auto-correlations and cross-corre­ evaluating government-sponsored re­ lations in rain gage data. search; (iii) establishment of task forces and advisory panels for large projects; and (iv) inclusion of one or CONFERENCE RECOMMENDATIONS more statisticians in each field experi­ ment team. 1. Statistical training should be Research in statistical method­ given greater emphasis in the aca­ ology applicable to weather modifi­ demic program of scientists and engi- cation programs should be promoted

73 and supported. Such research should modification by cloud seeding has include: the development and valida­ been the relative scarcity of "precipi­ tion of statistical models; devel­ tation-oriented" experiments. An ex­ opment of useful formulations of periment is "precipitation-oriented" meteorological hypotheses; and inves­ if it provides adequate information tigations of the statistical characteris­ about ground precipitation in the area tics of the measuring instruments used presumably affected by cloud seeding in this field. as well as in control areas. The doubts It is strongly recommended that concerning conclusions from commer­ any regulatory agency include as one cial cloud seeding operations were of its technical members or advisors a expressed forcefully after the publi­ person knowledgeable in statistical cation of the report of the Advisory principles and techniques. Committee on Weather Control. These Steps should be taken to work doubts arise from the possibility that out a voluntary system that assures various forms of selection bias exist, that commercial seeding operations as well as biases due to non-linear do not contaminate or vitiate scien­ transformations performed on the pre­ tific field work carried on in specified cipitation data. Still, no specific source areas of the country. Furthermore, of bias has been discovered that efforts of commercial seeders to would account for all of the positive gather valid evidence on the magni­ findings contained in the recent NAS tude of seeding effects should be en­ Panel analyses. couraged but should not be required In a field such as weather and cli­ of commercial cloud seeding opera­ mate modification, the statistical tions. methodology of bias elimination be­ comes particularly prominent. Ran­ domization is then naturally in the PRECIPITATION-ORIENTED foreground. Modern statistical design and eval­ EXPERIMENTS uation are based on a probabilistic model intended to present the impor­ A basic source of controversy and tant aspects of the phenomenon being uncertainty in the field of weather studied. The tools of modern proba-

74 bility theory are extremely flexible so that the underlying probabilistic THE EMPIRICAL APPROACH model may be far removed from the oversimplified concepts of "random­ It has been claimed that answers to ness" in the sense of serial independ­ the weather modification problem can only come from basic research. This ence, constancy of probability distri­ argument suffers from two defects: bution over time, or rectangularity of the probability density function. There are numerous precedents where the effectiveness of human But since experimental resources action has been empirically estab­ typically limit the obtainable sample lished beyond reasonable doubt many size or the period of observation, it years before any degree of under­ is important not to neglect the power standing of the underlying mechanism of test procedures and other dimen­ was attained. Thus, there is no basis sions of statistical efficiency. A multi­ for claiming that the understanding of dimensional or profile approach, the underlying atmospheric mecha­ based at least in part on the physical nisms is a necessary condition for a theory of the observed phenomena, determination of effectiveness of will be particularly effective. cloud seeding in generating ground precipitation. Among the ultimate aims of a planned "precipitation-oriented" ex­ Even a complete understanding periment must be a contribution to of the causal relations in cloud seed­ ing might fail to answer the question the understanding of the mechanism of the effectiveness of cloud seeding. by which cloud seeding succeeds or To answer the latter question on the fails in influencing ground precipita­ basis of the theory of the underlying tion. Therefore, the fact that precipi­ mechanism, one would still need com­ tation on the ground is to be carefully prehensive information concerning measured does not exclude the collec­ the distribution of the initial values tion of observations of other physical of the various atmospheric parameters. variables. This information is not at present

75 available and might be extremely duff i- the social psychologists will provide cult to come by. for observations on human perception The basic recommendation is that of weather modification activities, and a program of planned field experi­ the economist will concern himself ments be undertaken, possessing con­ with productivity effects, etc. The tinuity over a period of 5 to 10 years details of this aspect of experimenta­ and on a scale sufficient to permit tion must be worked out by experts geographic comparisons and differen­ in the respective substantive fields, tiation, as well as stratification ac­ but their conclusions will have to be cording to the type of seeding agent, carefully considered by the statisti­ mode of injection, cloud type, etc. cians in guiding the experimental de­ Provision should be made for the in­ sign. clusion of relevant precipitation data, in addition to other relevant physical variables. This program should be NUMERICAL MODELINO undertaken, designed, and evaluated in close association with statisticians AND SIMULATION with extensive experience in experi­ mental design. The techniques of numerical mod­ In view of the emphasis on the eling and simulation complement and physical aspects of weather modifica­ expand the potential of statistical tion experiments, it is important to analysis. In fact, they are high-pow­ remember that such experiments pro­ ered substitutes for paper and pencil vide a unique opportunity for moni­ calculation of the behavior of complex toring variables in the realm of systems under assumed conditions, biology, ecology, and social phenom­ parameter values, etc. Plausible values ena related to weather modification. to be assumed must still be generated Indeed, the design of weather and cli­ by empirical research in which statis­ mate modification experiments should tics is likely to play an important role. incorporate the needs of these fields. Modeling and simulation require the Ecologists will provide suggestions as existence of a mathematical theory of to design, making it possible to ob­ the phenomenon, making it possible serve the effects on various species; to establish a link between such van-

76 ables as cloud seeding and precipita­ tion. COMMISSION RECOMMENDATIONS When the mathematical model has not yet been developed or when The Commission recommends: realistic information on the relevant Statistical training for meteorol­ parameter values is not available, ogists should be promoted in academic numerical modeling may not be feas­ programs. Intellectual interchange be­ ible or fruitful. In such circumstances tween scientists and statisticians it may still be possible to arrive at the should be continued through periodic empirical relationship between seed­ seminars. ing and precipitation by intensive Statistical consultants should be systematic randomized and stratified made available to scientists in this field experimentation or by non- field through the support of confer­ experimental statistical analysis. ences where new projects can be pre­ sented, through use of statisticians as On the other hand there are situa­ evaluators of proposed work, and tions, as with large scale circulation through the support of task forces and problems, where field experiments are advisory panels, with statistician impossible, while a mathematical members, for large projects. Statisti­ model is available from dynamic cians should aid in the evaluation of meteorology and there is information proposals for government-supported on parameter values. Here numerical research. modeling can and should be used. Steps should be taken to assure In some cases mathematical model that plans for government-supported and parameter information exist, but research utilize statistical principles in an incomplete form, while field ex­ in determination of design and size. periments are possible though diffi­ Research in methodology should cult. Here a combination of direct be promoted. This includes the de­ statistical analysis together with nu­ velopment and validation of statisti­ merical modeling and simulation may cal models, uniformity trials and other be employed to advantage. investigations of the statistical char-

77 acteristics of the instrumentation in ments should be carried out under this work. complete control of the scientists, It is urged that any regulatory embodying the required technical agency that might come into being knowledge, possessing continuity over should have a staff statistician to a period needed for conclusiveness, guide efforts to gather valid evidence and on sufficient scale to permit geo­ on the magnitude and effects of cloud graphic conclusions, as well as statis­ seeding. tical stratification according to the A program of carefully planned type of seeding agent, mode of injec­ precipitation-oriented field experi- tion, cloud type, etc.

78 Water Resources, Office of Chief Engi- NOTNOTE neer, Bureau of Reclamation, Denver Fed- eral Center, Building 53, Denver, Colorado 1 List of Participants in Conferences Kruskal, William, Department of Statistics, Baughman, Robert C., Forest Fire Labora­ University of Chicago tory, U. S. Forest Service, Missoula, Mon­ Malone, Thomas F., Research Department, tana The Travelers Insurance Company, 1 Bearman, Jacob E., School of Public Health, Tower Square, Hartford, Connecticut Biostatistics Division, University of Min­ Markovic, Kadmilo D., Civil Engineering nesota, Minneapolis Department, Colorado State University, Bigelow, Julien, Institute for Advanced Fort Collins, Colorado Study, Princeton Mielke, Paul, Mathematics and Statistics De­ Bollay, Eugene, P. 0. Box 1022, Boulder, partment, Colorado State University, Fort Colorado Collins, Colorado Braham, Roscoe, Department of Geophysi- Peahl, Laurence E., Department of Mathema- cal Sciences, University of Chicago tics, Taft Junior College, Taft, California Brier, Glenn W., U. S. Weather Bureau, Reinhardt, Howard, Montana State Univer- Washington, D. C. sity, Missoula, Montana Brown, Jr., Byron Wm., School of Public Schleusener, Richard A., Institute of Atmos­ Health, Biostatistics Division, University pheric Sciences, South Dakota School of of Minnesota, Minneapolis Mines and Technology, Rapid City, South Court, Arnold, Department of Geography, Dakota San Fernando Valley State College, North- Simpson, J. M., U. S. Weather Bureau, Wash­ ridge, California ington, D. C. Dennis, Arnett, Institute of Atmospheric Snyder, Marshall, Department of Statistics, Sciences, South Dakota School of Mines University of Chicago and Technology, Rapid City, South Da­ Tick, Leo J., Data Processing and Computing kota Laboratory, Research Division School of Grant, Lewis 0., De­ Engineering, New York University, Uni­ partment, Colorado State University, Fort versity Heights, New York, New York Collins, Colorado Van Ness, John, Department of Statistics, Hindman, Ed, Department of Atmospheric Stanford University, Palo Alto, California Science, Colorado State University, Fort Willis, Paul, E. Bollay Associates, P. 0. Box Collins, Colorado N, Steamboat Springs, Colorado Hosler, C. L., Department of Meteorology, Wyckoff, P. H., Atmospheric Sciences Sec­ Pennsylvania State University, University tion, National Science Foundation, Wash­ Park, Pennsylvania ington, D. C. Hoyle, Michael, Cloud Physics Laboratory, Yevdjevich, Vunica M., Foothills Research University of Chicago, Chicago, Illinois Campus, Colorado State University, Fort Hurwicz, Leonid, Department of Economics, Collins, Colorado University of Minnesota, Minneapolis Youden, W. J., Applied Math Division, Na­ James, R. C., Bureau of Reclamation, Denver tional Bureau of Standards, Washington, Federal Center, Building 53, Denver, Colo­ D. C. rado Zopf, D., Eugene Bollay Associates, P. 0. Kahan, Archie M., Office of Atmospheric Box N, Steamboat Springs, Colorado

79 Like other recent technological ad­ The effects of the modification on vances, weather and climate modifi­ man's activities sometimes are direct, cation techniques, if fully effective, as in the case of fog dissipation, but THE HUMAN present humanity with unprecedented more often they operate indirectly opportunities and grave dangers. So through alterations in the hydrologic EFFECTS OF pervasive are the elements of weather system or in biological ecosystems. in the mind and works of man that an Their extent is especially troublesome alteration in one of them, even over to discover because a sustained pro­ WEATHER a small area, may provoke intricate gram of modification would change social changes. Some of these changes the climatic characteristics, and the AND CLIMATE are obvious but many are difficult to whole fabric of society, being subtly trace and puzzling to measure. adjusted to climatic means and ex­ A modification in a small area of tremes, is likely to change with them. MODIFICATION atmospheric circulation may cause The gains and losses that follow in shifts in the system of human produc­ the train of atmospheric alterations tion and communication, as when fog accrue to other processes of society dispersal makes possible an airplane as well as to economic production and flight that otherwise would be consumption. The organization of grounded. It also may lead to un­ livelihood may be affected, and the wanted conditions; thus, the measures to dissipate fog may increase the icing * The Commission had the benefit of of highways in the immediate airport thinking contributed by participants in a Symposium on Economic and Social As­ area. Modification at one place may pects of Weather Modification held at provoke changes in the atmospheric Boulder, Colorado on July 1-3, 1965 by the circulation elsewhere, as when there Department of Geography of the University of Chicago in collaboration with the Na­ possibly forms a "rain shadow" of tional Center for Atmospheric Research decreased rainfall to the detriment of under a grant from the National Science Foundation. Papers from that symposium a wheat farmer in the lee of an in­ shortly will be published in the University dUced increase which brings profit to of Chicago Geography Research Papers another farmer, or when the weather under the title of Human Dimensions of Weather Modification, edited by W. R. Der­ that pleases the wheat rancher causes rick Sewell. The list of participants in the distress to the nearby cherry orchard­ Symposium appears under Footnote I to ist. this chapter. Also see the Appendix. so quality and enjoyment of life may be fication, there are recommended meas­ enhanced or degraded. ures which should be taken by the Just how significant these chains of Federal Government to deal with im­ events may be on human activity still mediate questions of research and is largely conjectural. A few, such as field operations and to improve the the increase of hydroelectric genera­ nation's capacity to deal with larger tion from induced precipitation in the questions that loom in the future. drainage above a power plant may be In canvassing these issues the Com­ gauged with some confidence. Ac­ mission has drawn on the experience cording to some estimates, even highly and outlook of scientists who have modest precipitation increases at the worked with modification of other right times in cultivated areas are aspects of natural resources. There likely to be of major value. The direct has been only a little study of weather benefits to agriculture and forestry and climate impacts alone, but the ef­ from hail prevention and lightning fects of managing water and land suppression are likely to be significant yield many relevant lessons. and not too difficult to estimate. Many The final report of the Advisory effects cannot be measured readily. To Committee on Weather Control con­ the uncertainty of what modification tained an appendix relating to econ­ is within man's grasp therefore must omic evaluation. However, it did not be added his ignorance of the full instigate any concerted effort to im­ consequences of whatever modifica­ prove capacity to measure the human tion he may achieve. In the face of effects of weather and climate modifi­ uncertainty as to modification tech­ niques and of doubt as to their social cation. A few thoughtful studies were effect, a sound public policy encour­ made but the problem was neglected ages research on both techniques and for the most part. In making it possi­ effects so as to fully exploit what may ble for workers from anthropology, be an historic opportunity while economics, geography, meteorology, guarding against heavy or irreversible political science and related fields to damages to society. assess the current state of their After outlining several basic social knowledge, the Commission sought to problems attaching to weather modi- identify points where predictions now

81 are practicable and questions deserv ­ fore would be altered in some degree, ing more intensive study.' however slight. Enlarged wheat har­ vest would be the major outcome but by no means the only one. FOUR INTERLOCKING SYSTEMS As has been shown in the preceding chapter, the resulting shifts in eco­ It is important to recognize that al­ systems of plants, animals, soil, and though man may seek to modify microclimate are exceedingly difficult weather in order to benefit the quality to assess. If they cannot be identified of his life the result is rarely a simple fully their long-term significance for relation between an atmospheric con­ human activity cannot be gauged. dition and human activity in that Much the same problem is associa­ place. Atmospheric circulation, the ted with sectors of the hydrologic hydrologic cycle, biological ecosys­ cycle. Certain changes in stream flow tems, and human production are inter­ which would result from increasing locked. There may be a direct and precipitation or from decreasing evap­ largely limited connection between at­ otranspiration may be estimated. It mosphere and economic production, increasingly is possible to predict the as with fog dissipation or lightning modification in stream flow resulting suppression. More often, the benefits from changes in precipitation and tem­ and costs to the system of production perature. After a soil is saturated a and communication are felt indirectly small increase in rainfall may cause through changes in the hydrologic cy ­ a proportionately larger increase in cle and in biological ecosystems: a runoff. There is less knowledge about shift in the atmosphere changes one the likely effects of such changes on or more of the other three. Thus, an the movement of silt downstream, or increased amount of June rainfall in about the relation of rainfall intensity the High Plains of Colorado would to rates of gully cutting in and regions affect the production of wheat by add­ such as the Upper Rio Grande basin. ing to soil moisture and the capacity Lack of full understanding of the of plants for transpiration and of soils consequences has never been a reason for evaporation. Stream flow and for man to forbear modifying a part ground water supply in the area there- of his environment. He does not re-

82 frain from ploughing a Carolina field those measures which might bring because he is ignorant of the full ef­ serious or irreversible damages to the fects upon soil biota or upon runoff. environment. Arriving at such judg­ He has not held up the construction ments requires not only recognition of of storage dams in Kansas because of what is known and not known about doubt as to the readjustments in chan­ the atmospheric, hydrologic, and bio­ nel cross section and gradient which logical systems affected, but assess­ will take place downstream when the ment of how a change in one or all of flow is regularized. Moreover, in seek­ them will affect human life and of ing to alter the landscape in one way how one kind of change compares he may unwittingly cause damages to with another. others. There never is a time in the Weather and climate modification is present state of scientific knowledge distinct from the more conventional about air, soil, water, plants, and ani­ tools of environmental change in sev­ mals when these changes can be rec­ eral respects. It promises to ordinarily ognized in all their complexity. To affect areas distant from those where defer action until all the consequences modification is tried: more than any are tallied up would be to halt all new other readily available tool it may ex­ resource management. Yet, there have tend its effects across the frontiers of been times when the public decision countries, states, and nations. Its po­ to go ahead in ignorance has led to tentials for provoking local and inter­ bitter regrets, as when highly erosive national conflict therefore are great. soils have been ploughed and new cy ­ It usually has consequences for both cles of gully cutting have been trig­ hydrologic and biological systems. It gered; or as when channel works have is new. For these reasons there is caused heavy silting and dislocation greater likelihood that man at the out­ of downstream drainage systems. set will see the gravity as well as the In considering the possibility of a exciting opportunity of modification new tool of environmental modifica­ measures and that conscious attempts tion which may be coming into man's will be made to weigh their future hands, the challenge is to find a course consequences for society at the local, of action which without inhibiting national, and international levels. largely beneficial results will curb However, the techniques so far devel-

83 oped are cheap, readily moved from thereafter. Doubt as to the possibility place to place, low in capital invest­ of changing the weather led scientists ment, and often free from the hazard to ignore the challenge, and they were of irreversible shifts in the atmos­ supported in this by the silence of phere. These reasons tend to stimulate the Advisory Committee on Weather small-size operations widely dispersed Control as to the need, by the scepti­ in time and place, and to offset the cism of many atmospheric scientists, caution that otherwise might apply. by the debate in the academic com­ munity over the statistical methods used in judging cloud-seeding experi­ UNCERTAINTY ments, and by the caution of Federal agencies in encouraging new research. Uncertainty characterizes most There was no agency specifically thinking about the changes in natural charged to look into the human ef ­ systems that are subject to modifica­ fects, and within the National Science tion. Not only is there uncertainty Foundation the responsibility for about how much the atmospheric cir­ weather modification research was culation can be altered and what this lodged in the Section on Atmospheric would mean for the movement and Sciences. quality of water, plants, and animals, The principal lesson to be drawn but the consquences for human pro­ from this experience is that where un­ duction and communication are sub­ certainty is large, as it continues to be ject to similar doubt. with weather and climate modifica­ This is one of the factors account­ tion, the basic social implications will ing for the casual attention which has tend to remain unexplored unless ex­ been given to the social consequences plicit and sustained effort is made to of weather and climate modification stir up and support the essential re­ since publication of the report of the search. Otherwise, the human prob­ Advisory Committee on Weather Con­ lems are ignored until they burst into trol in 1957. An appended paper prominence on the heels of an im­ pointed out the need for more syste­ provement in technique. matic examination of the human ef ­ Where uncertainty is high there is fects of modification. Little was done much in favor of a public strategy which promotes diversification of ef­ seeding above a hydroelectric plant, forts rather than dependence upon the effects upon power production one line of action or research. Not downstream and in the generating only would this call for pursuit of network may be traced. A variant is studies on a variety of physical pro­ to assess the effect of rare meteorolo­ cesses, but it would suggest that the gical events. A second approach is to needs for and damages from theoreti­ ask at what points the social system cally possible modification would be would be sensitive to a change in examined in advance of perfection of weather conditions, and from this to techniques. In promoting a strategy estimate what would be the more de­ of diversification it is important, how­ sirable and undesirable changes which ever, to avoid spreading the research might be foreseen without regard to so thinly that no one project is re­ whether or not they currently are warding. Allocation of funds among practicable. different aspects of modification pre­ Under the first approach, the atten­ sumes a rough judgment of what kinds tion is directed toward discerning the of changes would be desirable in im­ likely impacts of modification which proving the quality of human life. promise early achievement. Under the second, the emphasis is on types of modification which should be sought TWO APPROACHES TO THE or avoided. The two approaches are not mutually exclusive, and they can HUMAN DIMENSIONS helpfully supplement each other. Both are recommended for early action. Investigation of the human dimen­ sions of weather modification can move along either one of two lines. BROADER CONSIDERATIONS A possible modification, such as pre­ cipitation induction or lightning sup­ Whether emphasis is upon fore­ pression, can be assumed and then an casting effects of practicable modifi­ effort made to estimate what the con­ cation measures or upon points in so­ sequences would be in the society. ciety which would be more sensitive Where a modification is tried, as in to weather changes, there is doubt

85 as to how far man properly should go fication could eliminate these ex­ in tampering with atmospheric sys­ tremes. A beginning at changing storm tems unless he is relatively clear as to or lightning nevertheless raises the the major consequences. Concern question of how far the human spirit with growing world population needs is enriched by the uncertainty and heightens the interest in gains from wonder and exhilaration that come the weather. Doubt as to human im­ with the restless, violent movements plications as illustrated by the diffi­ of the atmosphere. Any effort to as­ culty of assessing results of nuclear sess the social consequences of experiments, has raised new cautions weather and climate modification must concerning any novel or large-scale give weight to the esthetic and spirit­ interference with our environment. ual as well as purely material rewards. Great prudence is therefore warranted in practicing weather modification, and increased support is desirable to EVALUATINO SOCIAL EFFECTS explore its side effects, as well as its ability to achieve the desired results. The keen interest in precipitation Deep in human experience is a sense induction and fog dispersal shows of excitement and beauty in coping that their direct results are believed with the extremes of wind and rain to be highly beneficial. Certain elec­ and heat. To be sure, their enjoyment tric power utilities, airlines, and fruit does not always offset the discomfort growers have invested funds in re­ and suffering that lead men to com­ search and operations directed at monly adjust their clothing, dwellings, practical modifications. A public util­ transport and other practices to curb ity on the Pacific Coast concluded that the effects of weather. Yet in the driv­ in the drainage area of one of its res­ ing power of a winter or the ervoirs an increase of less than two sudden flash of summer lightning percent in annual precipitation would there are dramatic reminders of the clearly justify cloud seeding and that elemental forces with which the hu­ an increase of ten percent for a large man race constantly is striving to find watershed might be worth $200,000. its place. No presently conceivable An airline has estimated that the im­ program of weather or climate modi- mediate benefits in reduction of oper-

86 ating expenses from fog dispersal in relation to the impact on social organ­ an intermountain area were at least ization and process must also be iden­ five times the seeding costs. Ob­ tified. Because weather modification viously, if a farmer thinks he may in­ involves costs and may preclude al­ crease his per acre wheat yield from ternatives, its possible results must seven to eight bushels by rainfall in­ be compared with achievements ob­ duction or hail suppression at a cost tainable through alternative ways of of a few cents an acre he will be dealing with the vagaries and averages strongly inclined to take the risk of of weather phenomena. Man adjusts the expenditure even though the re- his activities to weather in countless suits are in doubt. It has been calcu­ ways and constantly is devising new lated that the estimated mean annual ones. The evaluation of fog dissipa­ losses of $250,000,000 from hurricanes tion requires not only the measure­ might be reduced by as much as one ment of benefits and costs at the air­ third if only modest reductions in port and in airline operations, but the storm intensity or slight changes in assessment of the benefits and costs storm paths could be achieved. Op ­ from installing equipment which could portunities for direct, beneficial ef­ land aircraft notwithstanding fog or fects in the economy are immense in­ from re-routing traffic on the ground sofar as genuine modification can be and in the air. managed with confidence. The meth­ Improved weather forecasts are one ods for computing such direct benefits major alternative to weather modifi­ are relatively well developed. cation. Sometimes they may comple­ In the sphere of human activities, ment each other, but in many instances the potential effects of modification an accurate forecast with sufficient on the quantity, timing, and geo­ advance warning, if accompanied graphic distribution of production and by other measures, would reduce or transportation are particularly strik­ even eliminate the gains from altering ing. But in evaluating the social effects a weather extreme. Thus, as much as of weather modification it is not 15-20 percent of flood losses may be enough to trace them through the tech­ eliminated in certain areas, if there is nological aspects of production activi­ sufficient notice, without changing the ties. Behavorial responses and their character of the flood or of the pre-

87 cipitation producing it. Severe crop casting, or any of the other alternatives losses from drought may be reduced must take into account the likelihood by alternate cropping if the drought that if certain of them are pursued can be predicted sufficiently far in consistently, the structure of the econ­ advance. Traffic can be re-routed omy will change so that it becomes around airports which will be closed less vulnerable to dislocation by by fog. Perhaps no industry is more weather. In drought areas a reor­ carefully prepared to take advantage ganization of farming practices might of a forecast of icy or freezing weather lead to agriculture which would be than is the public utility industry less vulnerable to the recurring dry which can move promptly to cope periods. Or, a continuing program of with weather emergencies. Inaccurate cloud seeding, if practicable, might forecasts also may cost heavily in raise the mean rainfall sufficiently to damages. encourage a major revision in type of Even in the absence of significant farming. This, in turn, could shift the forecasting improvements, there are service functions of nearby urban cen­ many other means of cutting down ters. dislocations caused by weather. In Without any conscious modification areas where drought occasionally of weather, the sensitivity of human brings acute crop losses, the social activity to weather may be reduced, impacts may be curbed by readjust­ as when air conditioning or insulation ment in cropping patterns, by breed­ of utility lines renders an area less ing or selecting drought resistant vari­ susceptible to extremes of tempera­ eties of plants, by supplementing the ture. During 1929-1962, the yield of water supply, by insurance schemes, corn in the Corn Belt increased in sev­ and by a variety of other actions, some eral steps related to the technology of which depend upon further scien­ of seed, cultivation, and fertilization, tific research for their perfection. A but during the same period the vari­ similar range of solutions applies to ation in yields due to weather ap­ dislocations caused by hail, excessive peared to decrease. 2 That is, the crop rain, fog, and lightning. production became less susceptible to To be realistic, measurement of the weather dislocations. In these and benefits and cost of modification, fore- other ways estimates of direct im-

88 pacts of weather modification must be tivity may be expected to reflect some corrected for longer-term structural readjustments that now are taken for adjustments. granted. Urban climates have under­ Research relating to the social im­ gone measureable change in tempera­ pact of weather on human affairs ture and air quality. The precise would prove fruitful even if no form amount still is in doubt. While few of weather or climate modification modern societies are so delicately ad­ were ever to be achieved. Deepened justed to rain or its invocation as are understanding of geographic relation­ certain of the organizations and social ships among weather characteristics controls of Pueblo culture in the and the economic system would be Southwestern United States, all of bound to aid in intelligent decisions them involve many adaptations. by both resource users and public Whether the relations of weather agencies in agriculture, transport, to human activity are isolated over a manufacturing, and other sectors of few days or many years, they ob­ the economy. The kind of refined viously are different from one sector knowledge about crops and rainfall, of society to another. The downpour or air transport and fog, or forest which fills a New York city reservoir growth and lightning which would be washes gullies in a farmer's field; the essential to careful estimates of social hurricane which disrupts a Florida impacts of weather modification would shopping center carries water to a be required for estimates of the sen­ nearby Everglades wildlife refuge. If sitivity of the economy to weather, it is assumed that there is any effect or for improvement in efficiency of upon processes elsewhere, the differ­ those activities by other means. ential results become even more One fundamental question deserv ­ marked. Were cloud seeding to have a ing scientific attention is the degree "rain shadow" of lowered precipita­ to which climate already has been tion or were hail suppression to re­ altered or may be altered in the future duce rainfall to the leeward, the com­ inadvertently by the hand of man. To plications would multiply. If it were the extent that either rural or urban to be shown that cirrus cloud forma­ climates have been so modified, the tion encourages smog conditions, then type and distribution of human ac- the health and heat budget of a metro-

89 politan area might be affected by air­ Judgment as to adoption of econom­ line operations upwind. A map show­ ically optimum solutions inevitably ing the area where weather elements is tempered by appraisal of what is are altered presents only a part of the likely to unfold in daily activities picture; it must delimit the extent of once the alteration is under way. It effects felt in nearby towns or in dis­ may well be that individuals will be tant markets. unable to take advantage of the poten­ These impacts are made especially tial benefits of weather and climate difficult to measure because people modification unless legal and institu­ may differ in their perception of tional changes are put into effect. weather conditions and of man's ef ­ fect upon weather. Just as many city dwellers in the path of a hurricane CONFLICTS OF INTEREST are unable to act rationally on the warning of high winds, so people in Even though there is no confident an area of weather modification may prediction of the extent to which for a variety of reasons fail to take weather and climate may be modified advantage of a changed condition. On in the future or of the full chain of the other hand, a farmer may act as impacts from such modification, it al­ though the weather is being modified ready is evident that at least four even when scientific verification is types of conflicts may be expected to lacking. In either case, the estimate arise as soon as a modification tech­ of the individually and socially ra­ nique is shown to be practicable. In­ tional solution does not turn out to deed, they will arise whenever there describe what people in fact do. A is any slight ground to think it may be workable public policy is based on practicable. Substantial groups in the prediction of what they will decide in nation already believe cloud seeding practical situations. The uneasy sus­ produces rain and perhaps even rain- picion of a nation that it is suffering shadow; their responses to private from cloud seeding to the windward seeding operations or government re­ is a political reality that must be faced search programs are based on these seriously, whether or not harmful ef ­ beliefs and range from enthusiasm to fects are known to occur. hostility.

90 These perceived conflicts are real in fication and another to lose. As al­ the minds of the people involved, and ready noted, this may apply both they cannot be ignored because they within a single area and between two lack scientific validation. This is par­ areas. ticularly true of the conflicts believed There is the possibility of con­ to extend across political boundaries. flicts between groups seeking to mod­ Below are examples of possible areas ify weather for different purposes or of conflict. for the benefit of different areas. Research on the techniques of Rather than there being unintended weather modification is likely to en­ effects upon other groups from one counter conflict with other research seeding operation, there can be direct programs unless there is clear agree­ ment as to the time and place of each conflict over the use of a site or field experiment. Otherwise, opera­ atmospheric condition. tions in the area may cause contam­ Public policy should recognize the ination and thus run the risk of in­ probability that all four types of con­ validating the observations elsewhere. flict may arise, and should seek to A proliferation of weather modi­ reconcile each of them equitably. In fication operations could make it im­ that effort its responsibility goes far possible to carry out carefully con­ beyond arbitrating conflict. It should trolled experiments. Were farmers in seek to prevent victimization, either the Great Plains to become generally of people who mistakenly think they convinced that cloud seeding could are gaining benefits that do not exist increase rainfall at critical periods or or of people who are unaware of dam­ could suppress hail, their activities ages being inflicted upon them by soon would cover the area so others. Without public intervention to thoroughly that without regulation it assure that proper records are kept would be difficult to run experiments and the findings are available to the to find out whether or not the opera­ interested parties, it will be impossible tions were in fact effective. to determine the true gains and losses. A conflict arises where one group It may be necessary that the govern­ stands to benefit from weather modi- ment judge the consequences, pro-

91 vided it is certain that suitable Insofar as practical modifications information is collected. are carried out they are likely to result In a situation where so much of the not only in specific gains and losses, knowledge is speculative, it is im­ but in widespread institutional changes portant that channels be kept open for in society. Thus far, the conflicts have research and for the sharing of re­ applied to small areas but in the future search findings. This is especially im­ they may extend over large areas. The portant where the social effects may readj ustments which result therefrom possibly reach across county, State, or will call for major changes in policy international borders. A policy of pas­ and organization as well as for arbi­ sively waiting for the conflicts to arise tration of competing claims and dam­ will in the long run exacerbate them ages. by permitting research to be impeded and by allowing the alledged injuries to show in tedious inconclusive judi­ DESIRABLE COURSES Of ACTION cial action or in peremptory legisla­ tive fiat. The time to guard against groundless contention is before it AnalYSIS Of SOMI Impacts arises. Because of the need for determin­ A university scientist who is anx­ ing more precisely the character of ious to experiment with cloud seeding social consequences of weather mod­ now feels more cautious than might ification, it is important that any be socially or scientifically desirable further government operations and about launching field work. If he government supported research deal­ shows positive effects he or his insti­ ing with modification be accompanied tution may be subject to damage suits by analysis of those consequences. If from those who think they have been the operations are entirely private, it injured by too much rainfall or by too would be desirable for the public to little or by rainfall at the wrong time. underwrite such analysis so that the Even if his results are negative or in­ social results could be recognized. conclusive, he still may be open to In cases where the operations are legal attack by those who genuinely in relatively small areas and do not feel themselves disadvantaged. induce structural changes in the econ-

92 omy, the methods of measuring im­ pacts may be adapted, with suitable ROV18W of MCI SIUMOS changes, from Federal experience with evaluating water development proj­ There should be critical review of ects. Much useful work has been done the methods followed and of the find­ on gauging benefits and costs from a ings so that the methods might be change in water occurrence. These improved and in time made uniform. methods will not be readily applicable It would be a mistake at this stage to to such special questions as the as­ attempt to set standards for social sessment of recreation benefits and evaluation of weather modification. At present there is no guarantee that the distribution of benefits and costs the analyses of different aspects outside the target area. Nor will they could be compared with one another. be particularly helpful in recognizing Working from the experience with institutional adjustments that would interagency cooperation in water re­ be prominently involved in sustained source studies, the Foundation should modification operations. The findings convene a panel of representatives would be rough, but they would give from interested public agencies and an idea of the order of magnitude of from research institutions to examine results and would suggest problems of analytical methods and to suggest evaluation deserving early attention. ways of refining them. The panel Much can be learned promptly from would be expected to appraise meth­ studying the economic aspects of legal ods used for the indentification and conflicts which already have arisen. measurement of impacts and the use If Federal and private agencies are of such evidence in evaluating weather modification and alternative measures. not ready to undertake this type of It could draw heavily from experience analysis, the National Science Foun­ over the past two decades in attempt­ dation should be prepared to support ing to gauge the effects of water proj­ it. After a few years, the analysis ects on farming, nearby towns, and might be attempted more selectively. on more distant areas. It would report At present, it should be tried wher­ its findings to the Foundation and the ever practicable. interested agencies, then making pub-

93 lic its evaluations. At an early time, it these and related problems would be might well use the data from one of to enable a scholar broadly acquainted the comprehensive river basin studies, with the social sciences to spend a such as the Delaware Basin study, to year examining the field of weather test the suitability of the methods in modification with a view to suggesting common use. especially difficult or promising lines of investigation. So little systematic work has been done to date, beyond Re"Gearch on sociai Enects the interdisciplinary exchanges al­ ready instigated by this Commission, The support and encouragement that it would be helpful to have a which the National Science Founda­ more thorough appraisal of oppor­ tion has given to research on physical tunities. The exploratory studies of processes of the atmosphere should be weather information and prediction extended to research on those rela­ by the U. S. Weather Bureau and the tions between weather and human ac­ Rand Corporation, and the scattered tivity which possibly would be economic and geographic investiga­ affected by weather modification. This tions of the relation of climate to should include the nature of external farming, commerce, and transporta­

economies and diseconomies from tion need to be extended widely. 3 modification operations, the conse­ It should be emphasized that virtu­ quences of shifts in ecosystems, and ally all of the research which would the institutional changes that may re­ be initiated would, if sound, yield sult. Methods for measuring changes findings that would be useful in mak­ in crop production and the losses ing more efficient adjustments to from fires are well developed, but im­ weather conditions even if no modifi­ pacts on recreation and on biological cation were ever to be practiced. The communities are rough at best. Many same method for estimating the bene­ of the impacts will show in revision fits to a manufacturer from a change of organization of individual and com­ in occurrence of rainfall would be munity enterprises. helpful in calculating the gains from One means of stimulating further an improved rainfall forecast or from thinking about fruitful approaches to a technical innovation that would

94 render him less vulnerable to damages than precipitation and incoming radia­ from intense rainfall. tion is difficult in any event. The analysis must be developed in prob­ abilistic terms, and the present rela­ Freedom for EXPOrimenwon tionship to human activity must be investigated with sufficient precision In order to permit field experiments to permit judgment as to the degree with methods that do not threaten to which prevailing geographic pat­ seriously deleterious results, it is es­ terns of farming, transportation, in­ sential to provide for indemnification dustry, and recreation would be of investigators supported by Federal altered in response to a change in funds against damage suits. weather characteristics. In the near future, it would be de­ sirable to explore types of models ResearcH ON BUIC ReiallORSDIP3 which might be used and the data understanding which they would re­ If there were relatively full under­ quire. An activity analysis type of standing of the complex relationships model might well provide a flexible among weather characteristics and framework without pre-judging the human activity, the task of estimating nature of relationships to be investi­ impacts of weather modification would be more nearly straightfor­ gated. An input-output model would ward. Lacking such understanding in merit investigation but would offer all sectors of society, efforts should complications. Whatever the form of be encouraged to discover them. In model selected, considerable empiri­ the long run, it might be practicable cal study would be required in narrow to develop a model of the national sectors before its application to larger economy which would be sufficiently parts of the economy would be war­ detailed and sensitive to predict the ranted. Thus, the possible shifts in effects of varying one or more of the cropping and manufacturing locations daily weather inputs. The methodo­ would need to be specified for differ­ logical problems are enormous. Meas­ ent magnitudes of change in each urement of weather conditions other weather element. Cautious but vigor-

95 ous steps should be taken in this di­ deavor, there is likely to be a lag rection. between technical knowledge and its application. Differences according to culture groups may be expected. Re­ Research on oecision Processes search on the conditions of decision making in these circumstances would Both the nature of weather proc­ illuminate discussion of suitable pub­ esses and the current knowledge lic policy by showing the choices that about them require that most human are open to public agencies and by decisions as to weather modification increasing the ability to predict the must be made in the face of uncer­ ways in which weather users may re­ tainty. This imposes special restraints spond to the unfolding technology of on public agencies and it increases the weather modification. The National difficulty of predicting how individual Science Foundation should encourage farmers, manufacturers, and others such investigations. who are directly affected by weather would respond to changes in weather characteristics. There is little evidence Research on IoaOverteot as to how many people would take advantage of an alteration in weather Modificalons even if it could be assured, or that they would do so in an economically Although public interest tends to efficient manner. A flood-plain dweller concentrate on the possibility and may fail to heed an accurate flood effect of new techniques for conscious forecast because he does not under­ modification of weather, it is desir­ stand what practical steps he could able to look into the degree to which take; a farmer may not take advantage past and present human activities of increased rainfall because condi­ cause inadvertent changes in weather tions of credit or farm organization and climate. Investigations of those discourage him. It appears that people alterations require the collaboration vary from place to place in their belief of scientists working on atmospheric, in the effectiveness of weather modifi­ biological, hydrological, and social cation. As in all areas of human en- problems. Historical and archeological

96 evidence may need to be compared The method of assessing impacts with current geography and with me­ of weather modification should be the teorological data. The train of events subject of research looking to its re­ between human action and weather finement and extension. characteristics should be traced with Freedom of field experimentation attention not only to physical altera­ should be supported by providing in­ tions in climate, but to resulting modi­ demnification of Federally financed fication in the quality of human life. experimenters against damage claims. Research should be encouraged on the basic relationships between weather characteristics and human RECOMMENDATIONS activity. Decision making processes in the The Commission recommends: face of uncertainty as to weather Steps should be taken to assure modication and its effects should be that wherever field experimentation subjected to careful investigation as or commercial operations are under­ a means of increasing the govern­ taken in weather and climate modifi­ ment's ability to predict the results of cation arrangements be made to study alternative policies and methods for the social consequences. weather modification. A special panel should be estab­ Interdisciplinary study of modifi­ lished to exchange and give critical cations which man makes inadvert­ review to the results of such studies. ently should be encouraged.

97 Lester Goldner, Division of Air Pollution, FOOTNOTES U. S. Department of Health, Education and Welfare Ivars Gutmanis, Division of Air Pollution, 1 Symposium on the Economic and Social U. S. Department of Health, Education Aspects of Weather Modification, July 1-3, and Welfare 1965. List of participants: Robert L. Hendrick, Senior Research Scien­ tist, Travelers Research Center Edward A. Ackerman, Carnegie Institution James Hibbs, U. S. Weather Bureau, Depart­ of Washington ment of Commerce Jack Barrows, U. S. Forest Service, Depart­ Howard Hines, Director, Division of Social ment of Agriculture Sciences, National Science Foundation Marston Bates, Department of Zoology, Uni­ Leonid Hurwicz, Department of Economics, versity of Michigan University of Minnesota Boynton Beckwith, Assistant Director of Paul Julian, National Center for Atmos­ Meteorology, United Airlines pheric Research Sherman W. Betts, Interdepartmental Com­ Archie Kahan, Bureau of Reclamation, U. S. mittee for Atmospheric Sciences Department of Interior Carl von E. Bickert, Industrial Economics Robert W. Kates, Graduate School of Geog­ Division, Denver Research Institute raphy, Clark University Reid Bryson, Department of Meteorology, John W. Kirkbride, Statistical Reporting University of Wisconsin Service, U. S. Department of Agriculture Horace Byers, Department of Geophysics, R. Koopmans, Department of Economics, University of Chicago Yale University Emery N. Castle, Department of Agricultural Robert Lucas, Lake States Forest Expt. Sta­ Economics, Oregon State University tion, University of Minnesota A. R. Chamberlain, Vice President, Colorado Fremont J. Lyden, Department of Political State University Science, University of Washington Marion Clawson, Resources for the Future, Arthur Maass, Water Resources Center, Inc. Harvard University Norman Crawford, Department of Civil En­ Marion E. Marts, Vice Provost, University of gineering, Stanford University Washington James A. Crutchfield, Department of Eco­ Richard Meier, School of Natural Resources, nomics, University of Washington University of Michigan Leslie Curry, Department of Geography, Gilbert F. White, Department of Geography, University of Toronto University of Chicago Donald L. Eberly, Meteorologist, Pacific Gas Donald Michael, Institute for Policy Studies and Electric Co. Edward A. Morris, Bronson, Bronson & Robert D. Elliott, President, North American McKinnon Weather Consultants Jack C. Oppenheimer, Executive Secretary, William Garrison, Department of Geogra­ Special Commission on Weather Modifi­ phy, Northwestern University cation Donald L. Gilman, Extended Forecast Divi­ Allan Pred, Department of Geography, Uni­ sion, U. S. Weather Bureau versity of California

98 Reginald C. Price, Deputy Director, State of Lowell Ashby, Department of Commerce California, Department of Water Resources Jack Barrows, U. S. Forest Service Walter Orr Roberts, National Center for At- Robert Cain, National Science Foundation mospheric Research Emery N. Castle, Oregon State University Thomas Saarinen, Department of Geogra­ Frank Hersman, National Science Founda- phy, University of Chicago tion Richard Schleusener, Director, Institute of James Hibbs, U. S. Weather Bureau Atmospheric Sciences, South Dakota Howard Hines, National Science Foundation School of Mines and Technology H. R. Josephson, U. S. Forest Service Anthony Scott, Department of Economics, Allen Kneese, Resources for the Future University of Chicago Karl Lee, U. S. Bureau of Reclamation W. R. Derrick Sewell, Department of Geog­ Hoyt Lemons, Department of Defense raphy, University of Chicago Jack C. Oppenheimer, National Science Bernard Silverman, Meteorologist, U.S.A.F. Foundation Meteorological Lab. Truman Price, Department of the Interior Stephen C. Smith, Department of Agricul­ Louis Quam, Office of Naval Research tural Economics, Colorado State Univer­ Stephen C. Smith, Colorado State University sity Harry A. Steele, Department of Agriculture Evon Z. Vogt, Curator, Middle American Peter H. Wyckoff, National Science Founda­ Ethnology, Harvard University tion Andrew Wilson, Department of Geogra­ The question of how the basic relations phy, University of Arizona among weather and economic activity might Peter H. Wyckoff, Director, Weather Modi­ be investigated through a comprehensive fication Program, National Science Foun­ model was outlined by Edward A. Acker­ dation man of the Carnegie Institution of Washing­ The problems of measuring the impacts of ton and was the subject of a special review by John A. Edwards of Oregon State Uni­ weather modification were examined against versity. the background of experience with evalu­ ating water management projects with a 2 Lawrence H. Shaw and Donald D. Du­ group of consultants consisting of Emery rost, "The Effect of Water and Technology Castle of Oregon State University, Allen on Corn Yields in the Corn Belt, 1929-62," Kneese of Resources for the Future, W. R. Agricultural Economic Report, No. 80, Wash­ Derrick Sewell of the University of Chicago, ington: U. S. Department of Agriculture, and Stephen C. Smith of Colorado State 1965. University. Useful suggestions also came from a discussion of social evaluation of R. R. Rapp and R. E. Huscke, Weather weather modification experiments and op­ information: Its Uses, Actual and Potential, erations held in Washington, D. C. on Sep­ Santa Monica: Rand Corporation, 1964. tember 20, 1965. Those participating in this Memo RM-4083-USWB U. S. Weather Bu­ discussion were as follows: reau, The National Research Effort on im­ Gilbert F. White, University of Chicago, proved Weather Description and Prediction Chairman for Social and Economic Purposes, Wash­ Keith Arnold, U. S. Forest Service ington, 1964.

99 The drawing of conclusions as to Similarly difficult problems of choice the legal and legislative aspects of will be posed by even the limited LEOAL AND weather modification is hampered by capability of precipitation induction uncertainty as to the scientific capa­ now visualized. In a sense, ability to bilities in the field. If one possessed control the atmosphere may create LEOISLATIVE or seemed likely to possess in the near more problems than it solves. For na­ future the technological capability of tions as well as individuals the avail­ ordering weather, the ramifications to ability of alternatives may turn out ASPECTS our society and hence to our legal to be more disruptive than the hard­ system would be enormous. Even a ships of want. limited capacity to modify weather Given the present state of the art, would pose problems of great com­ extended speculation as to the neces­ plexity. The nature of these problems sary responses of the laws would seem is illustrated by what might result if unwarranted in a report of this kind. the present experiments in the "dis­ The temptation is strong to put aside arming" of hurricanes are successful. At first blush one would suppose that In considering this facet of the problem the Commission addressed questionnaires to no one could object to the dissipation the 50 state governments and to the 64 per- of destructive storms such as hurri­ Sons OF organizations (including 7 Federal agencies) who have been conducting weather canes. However, there seems to be at modification research activities or commer­ least some opinion that a substantial cial operations. The National Science Foun­ amount of the rainfall in the North­ dation contracted with the Southern Meth­ odist University School of Law to have Prof. east comes about as a result of hurri­ Howard J. Taubenfeld undertake in coopera­ cane activity. It might, then, turn out tion with the Commission's Executive Sec­ that hurricanes are a necessary part retary, Jack C. Oppenheimer, Esq., a survey, analysis and summary of the data contained of the distribution of rainfall in a sub­ in the responses. The result is the report to stantial section of the United States. be published by the NSF in January, 1966, Assuming both the power to dissipate entitled "Weather Modification: Law, Con­ trols, Operations" (see the Appendix). This hurricanes and the need for rainfall chapter is in large part based upon this in the Northeast, how is the decision study. Acknowledgment is also made to the between the risk of catastrophic helpful suggestions of NSF General Counsel William J. Hoff, Deputy General Counsel storms and the ending of the drought Charles B. Ruttenberg, and attorney Joseph to be made? R. Schurman.

100 the legal question until the science Weather modification activities can and technology have developed a little result in two more or less distinct more. On the other hand, with the kinds of injury to members of the apparent ability to modify weather public. The first kind is damage caused intentionally, albeit to a limited ex­ by destructive weather conditions tent, and since it is not certain that such as flood, hail, hurricanes and the efforts do not result in some unin­ like. Damages attributable to such tended modifications, one cannot conditions, assuming satisfaction of wholly dismiss the problems. More­ other prerequisites to recovery, would over, whatever the scientific truth may be compensable under traditional be, weather modification activities are standards. The second kind would being conducted and many people result from the change in climate of a believe those activities have effects particular locality, e.g., lowering or both beneficial and deleterious. In­ raising the level of rainfall in a local­ deed, some twenty-two states have ity below or above that which would already enacted legislation dealing have fallen but for the modification. with those activities. The result is Assuming that the level which would that the law is already involved with have fallen naturally could be estab­ weather modification in many ways, lished, damage could be of widely so that for better or worse considera­ diverse kinds; from the blighting of a tion must now be given to some of the resort owner's season to the ruining legal aspects of weather and climate of a particular crop.* modification. Although liability for weather modi­ The existing involvment of weather fication activities, and "property in­ modification with law is, broadly terests in weather," have been the speaking, of two kinds: (1) the body of subject of a good deal of speculation rules governing the responsibilities in the legal literature, there have been and liabilities of weather modifiers (or only six lawsuits in which the ques­ those who employ their services) to tions have been litigated. Of these, other members of the public; and (2) three were suits by nearby land- regulation by government (most often * The categories are not mutually exclu­ by the states) of weather modification sive. Drought, for example, might belong to activities. both.

101 owners seeking damages or injunctive the preview they afford to the kinds relief on account of floods allegedly of conflicts one can expect if large- caused by weather modification ac­ scale weather modification becomes a tivities. In two of the cases the trial reality: resort owners against city court denied relief on the ground that fathers; ranchers needing precipita­ no causal connection between the ac­ tion of any kind against farmers want­ tivities and the floods had been estab­ ing to suppress hail; public utilities lished. The third resulted in a jury fearing ioss of hydroelectric power verdict for the defendant weather against homeowners fearing disastrous modifier.* The other three suits floods because of the creation of de­ sought injunctive relief against inter­ structive weather conditions. ference by the weather modifier with The chief obstacle to recovery for the plaintiff's property rights in damage most likely will be the prob­ weather. In one, a suit by resort own­ lem of proving a causal connection ers against the City of New York, the between the activity and the damage. New York court held that the public It should be stressed that legal causal­ interest in ending a prevailing drought ity and scientific causality are two outweighed the resort owners' interest markedly different things. It is quite in good weather. In another, the only possible, as the decision under­ decision against the weather modifi­ scores, that liability could be imposed ers, a Texas court granted an injunc­ in circumstances which might not jus­ tion against hail suppression activities tify the scientist in finding that a carried on by farmers in favor of causal relationship existed. neighboring ranchers who wanted pre­ Assuming that the requisite causal cipitation in any form, including hail. connection can be established, the The last of the suits is still pending in Pennsylvania .** * The case was based on claimed negli­ gence and the jury verdict could mean This handful of cases does not, of either that no negligence was found or that course, provide a firm basis for pre­ no causal connection was found between dicting how the law will develop. The the acts complained of and the damage. ** In addition to these actions there is a cases do, however, provide food for pending criminal proceeding against weather thought about a number of aspects of modifiers for violation of a municipal ordi­ the problem, not the least of which is nance prohibiting such activities.

102 next question is whether the injury is to control airspace over one's land; legally compensable. This could de­ to the right to acquire wild animals by pend on the applicable rule of liabil­ reduction to possession; to rights in ity, i.e., whether the actor would be water courses, or percolating, or dif­ liable only in the case of fault, negli­ fused surface waters. The pertinence gence or some more reprehensible of some of these analogies is more ap­ conduct, or in the absence of fault parent than real. Rights to airspace, under a rule of strict or absolute lia­ to the extent they are recognized, are bility. The applicable rule might in justified as necessary to protect en­ turn depend on the nature of the ac­ joyment of the underlying land. The tor; whether he is a private operator, relationship between the underlying government contractor, or the govern­ land and particular clouds passing ment itself. There is not much point overhead, however desperate the need in speculating at this time as to the for water may be, is quite different. likelihood of a particular rule of lia­ The considerations bearing on the bility's being adopted. Suffice it to say award of control over clouds are not that if a causal connection could be all the same as those supporting the established, imposition of tort liability rule as to animals. A watercourse con­ on one theory or another would seem notes a stream flowing in a reasonably likely. definite channel with distinct parcels Where the injury claimed is the re­ of land bordering on the stream. In duction or raising of the precipitation the Eastern United States, to the ex­ level, a substantially different ques­ tent that property rights exist, they tion is involved. The answer will turn arise by virtue of the ownership of on whether or not a person is held to the bordering land, a circumstance not have a property interest in a particu­ present in the case of clouds. And the lar kind of weather. It is much too rule of most Western states giving early to tell how the law will answer rights to surface water to the first to the question of who owns the clouds. appropriate it could lead to if A number of possible theories have applied to water in the atmosphere. been advanced based on supposedly Problems of percolating waters, i.e., analogous situations. The right to all subsurface waters other than those clouds has been compared to the right in underground streams, are most

103 nearly analogous. But, here again sion this decision would make possible rights, to the extent they exist, are the barring of any weather modifica­ based on ownership of the surface tion activities except over one's own land. This does not mean that there land. It should be emphasized that the are not valuable lessons to be learned relief sought in these cases was in­ from the development of water law. junctive, and that conceivably one or The adjustment of competing inter­ both cases might have come out dif­ ests, and the handling—especially in ferently if, instead, damages had been the Western States—of the problem sought. That courts would be natur­ of scarcity of vital natural asset give ally reluctant to enjoin a municipal- valuable insights. When all is said and ity's efforts to end a drought because done, however, the problems of a resort owner's good weather was weather and climate modification are threatened does not mean that in an infinitely more pervasive and complex appropriate case they would not re­ than those of water and should be quire the community to recompense decided on their own merits rather the resort owner.* The "natural rights" than on the basis of wholly or partly theory of the Texas decision, while a inapt analogies. sufficient basis for enjoying any inter­ The two cases which have posed ference, does not offer much hope for the question of "property rights in an award of damages in the light of weather" have reached different re­ nature's well-known unreliability. If, sults, at least on the surface. In New on the other hand, one measures the York, the court, while impliedly con­ Texas decision by the New York test ceding some interest of the resort of balancing the interests of the par­ owners in "good weather," felt that ties concerned, it may represent a not their interest was outweighed by the so unreasonable vote for the status interest of the community in ending quo as between the competing claims a drought. The Texas case, on the of ranchers and farmers. other hand, held that the complaining Interesting as these isolated decis- ranch owners had a "natural right to * In the actual case, the court found that such precipitation (from clouds over the experiments by the city would not in­ their land) as nature chooses to be­ terfere with the resort owners' business to stow." Carried to its logical conclu- an appreciable extent.

104 ions may be, one cannot begin to dis­ the problem is not materially different cuss rights in weather meaningfully from the case of other hazardous gov­ until the capability for control be­ ernment activities. The nature of that comes clearer. If weather modifica­ problem and the possible solutions tions of significance become scientifi­ have been much discussed in recent cally feasible, the implications to years and will be touched on only society and law will be such as to briefly. require a rethinking of many legal The most recent study of indemnifi­ concepts. Legislation far broader than cation was conducted by the Legisla­ that suggested below will be needed tive Drafting Fund of Columbia to order relationships between the University for the National Security various interests, private and govern­ Industrial Association, under the di­ mental, in the light of the new capa­ rection of Professor Albert J. Rosen­ bility. In short, it is premature to make thal of the Columbia University recommendations about the rules of School of Law. In the report, Cata­ law governing "property rights in strophic Accidents in Government weather" or the liabilities of weather Programs, the authors, although pri­ modifiers for damages found to have marily concerned with Defense De­ been legally caused by their activities. partment and NASA activities, pay at It is not, however, premature to least passing attention to weather make recommendations about one as­ modification programs. The recom­ pect of tort liability. This is with mendations of the report can be taken respect to indemnification of persons as the starting point for consideration engaged in weather modification re­ of the problem. search activities on behalf of the gov ­ Traditionally, the problem has been ernmen t.* A strong argument can be made that persons who carry on gov­ * The problem of tort liability of private ernment-sponsored research activities operators may be important insofar as they are concerned and, indeed, may be impor­ should be protected against liability tant to members of the public to the extent claims; and that members of the that there is uncompensated damage for public who are injured as a result of particular activities. At the moment, how­ ever, there does not seem to be any justifi­ such activities should receive ade­ cation for a government program to handle quate compensation. In most respects liability on account of private operations.

105 viewed as one of indemnifying gov­ be imposed, it does not affect the right ernment contractors against liability of a member of the public to a judg­ for damage caused the public, a!­ ment in the first instance. though of late it is being seen increas­ Whether the government should go ingly as one of protecting the public. beyond mere indemnification and However viewed, it is widely agreed more directly ensure public protec­ that the problem requires legislative tion, for example, by enacting a law of solution. Specific legislation has been strict liability for contractual activ ­ enacted empowering a number of gov­ ities, is a subject now being debated ernment agencies to indemnify con­ in the Defense Department and NASA. tractors against liability. Except for In extending the Atomic Energy In­ the Price-Anderson Amendment to the demnification legislation the Joint Atomic Energy Act, no satisfactory Committee on Atomic Energy specifi­ legislation to deal with potentially cally called attention to the need for castastrophic liability has been en­ inquiry into that problem. Not much acted. point is seen in adding to that discus­ Quite apart from the question of sion. As a general rule a member of protection of the public and fairness the public injured as a result of gov­ to the contractor is the question of ernment-supported weather modifica­ government self-interest in having re­ tion research should be treated the search performed. In this respect there same as one injured by DOD or NASA are already some intimations that the activities. It is to be hoped that indem­ problem of liability may have an in­ nification legislation covering those hibiting effect on researc h.* agencies and others will soon be en-

Unless frustrated in administration, * "Introduction to Weather Modification: an indemnification statute could pro­ Law, Controls, Operations," H. J. Tauben­ vide a satisfactory answer to the prob­ feld, et al, to be published by the National lems of contractors.** From the point Science Foundation in January 1966. See the Appendix. of view of the public the protection ** We have discussed the problem in afforded is indirect. While government terms of contractors. It is conceivable that similar problems would be met in the case indemnity ensures payment of a judg­ of grantees, and there is no theoretical reason ment once secured, up to the limit why they too should not be covered where of any ceiling on liability which may appropriate.

106 acted. Weather modification activities the primary aim of which would seem should be covered. It is more impor­ to be active control of weather modifi­ tant that some protection be afforded cation activities with the collection than that equality of treatment be pre­ and evaluation of scientific informa­ served. If no general legislation is en­ tion as an important adjunct of con­ acted, special indemnification legisla­ trol; and 2) those which aim primarily tion for weather modification should at the collection and evaluation of be. Needless to say, this recommenda­ information. In the first and larger tion should not be construed as imply­ group restrictive laws necessitate a ing that any causal connection between license or registration for operation. particular weather modification activ­ Where a license is required, it usually ities and injuries to property has been can be obtained only after a state­ established. As noted above, legal ment is filed showing the qualifica­ cause may be found whatever the tions of the operator, his financial opinions of scientists, and it is the responsibility, the nature of the pro­ risk of liability rather than the scien­ posed work and the payment of a fee. tific reality which is important here. Only two of the States list specific The second area of involvement of criteria of competence. In one case weather modification with the law is the operator must be a professional that of regulation. Considering the engineer. In the other the operator small amount of activity in the field, must be a member of, or qualified for the amount of State legislation is membership in, the American Meteor­ rather staggering. Twenty-two States ological Society. The methods of as­ now have statutes dealing with at suring financial responsibility differ least some aspects of weather modi­ widely as well. Public notice is often fication and others have legislation required before activities can be un­ under consideration. Most of the dertaken. As a general rule qualifica­ statutes date from the period of the tions, financial responsibility, etc. are early and middle 1950's, but a few evaluated by boards and commissions. have been enacted in the last five At least eight States have special years. weather control boards, presumably In general, State statutes can be di­ with special expertise in the field. vided into two broad classes: 1) those Most States require reports after the

107 conduct of the weather modification stantial dislocation to operators. It is activity. interesting to note that, nevertheless, Several States assert sovereign there was a widespread agreement rights to the moisture in the clouds or that Federal legislation would be wel­ atmosphere above their land mass. come. New Mexico, Louisiana and Colorado For present purposes, the signifi­ limit weather activities which may cance of State regulatory legislation affect other States, although in the is not so much its past effect but its case of the latter two, only on a re­ potential impact on programs which ciprocal basis. One State, Maryland, may be desirable. Obviously, any leg­ has now barred all weather modifica­ islation which prohibits weather mod­ tion activities for a two-year period. ification activities—if construed to The Pennsylvania legislature recently apply to research as well as commer­ adopted a bill to prohibit all weather cial activities—could have a serious modification activities except research effect on desirable programs. State by universities and the State and Fed­ licensing requirements in some circum­ eral governments. The bill was vetoed stances could place a serious burden by the Governor. on any experiment crossing State lines, To gauge the operation and adminis­ and most experiments of any size tration of these statutes, the Commis­ would be likely to do so. The nature sion sent questionnaires to all States of the subject, including the likelihood and all known commercial operators that the effects of activities will not and researchers active in the field. The be restricted to a single State make it answers to those questionnaires, seem probable that Federal regulatory which are analyzed and summarized legislation will ultimately be needed. in the report referred to above entitled The question of immediate interests is "Weather Modification: Law, Con­ whether anything needs to be done trols, Operations," would indicate that now. the effect of regulatory legislation on At the present time, the only Federal weather modification has been slight. "regulation" of weather modification To be sure, there were instances of activities is the report form required dissatisfaction, but little evidence that to be filed annually by all operators existing laws have caused any sub- of whose activities the National Sci-

108 ence Foundation has become aware. program recommended in this report The report is required pursuant to requires that research have a very the authority of the Foundation under high priority. This means that State PL 85-510, "to obtain by regulation, and local legal rules cannot be per­ subpoena, or otherwise, such informa­ mitted to interfere with research ob­ tion . . . as may be deemed necessary jectives. Interference can be of two or appropriate . . . to carry out kinds. First, the local rules may im­ the program of study, research and pose liability for injuries caused by evaluation in the field of weather research projects; the threat of liabil­ modification." This after the fact sys­ ity may act as a deterrent to research­ tem of information collection has re­ ers. For the reasons set forth above, cently been changed. Effective January it is not believed that the time is ripe 1, 1966, the Foundation adopted a new for postulating new rules of liability. regulation requiring that all weather Consequently, the best way of dealing modifiers keep certain records, and, with the possibility of this kind of in addition, give the Foundation thirty interference is by indemnity or other days' advance notice of any proposed protection against liability. activity. The purpose of the record- There remains, however, the possi­ keeping requirements is, in the words bility of direct interference by injunc­ of the Regulation, "to develop infor­ tion, either pursuant to a statute or mation for use in carrying out the ordinance forbidding or restricting responsibility of the National Science weather modification activities, or as Foundation to support a program of in the Texas case under the courts' study, research, and evaluation in the general power to prevent interfer­ field of weather modification . . ences with property rights. It is worth It is too early to tell how the new noting that where timing is important, regulation will work, and whether its even a temporary injunction can have objective will be accomplished. While disastrous effects on a research proj­ it is conceivable that no additional ect. So long as the work is carried on action will be necessary, it seems directly by the Federal government it likely that even for the immediate would seem to be immune to injunc­ future further steps will be necessary. tion. If it were carried on by a govern­ Fulfillment of the objectives of the ment contractor, whether a private

109 company or an institution, the immun­ supported, persuasion will probably ity would be much less clear. And, be sufficient. Where commercial oper­ where research is carried on pursuant ators are involved persuasion may be to grant, there would appear to be no less effective. In either event, power governmental immunity whatsoever. to halt interference should be avail­ Provision should be made to ensure able where necessary to protect the that all properly conducted experi­ integrity of government operations. ments including those conducted by The power does not exist today. The contract or grant should be immune power to halt interference and the im­ to local interference. munity from state interference need A somewhat different problem is not be unlimited. Room can be left for posed by the possibility that some reasonable accommodation of the weather modification activities may needs of local governments. But, pri­ physically interfere with government ority of the Federal program must be activities. As pointed out elsewhere established. in the report, the nature of cloud- One other suggestion for regulation seeding experiments is such that there —that private operators be required is a real possibility of contamination to evaluate their operations—should by other seeding operations in the be discussed. Because of the nature same general location. Such contami­ of research in weather modification, nation can be expensive and scien­ and the nature of the problem of eval­ tifically catastrophic in view of the uating results, it would be particularly limited opportunities available for desirable to use all experiences in­ some kinds of research. A part of the cluding those of private operators. If problem can probably be taken care of full advantage is to be taken of their by the proposed Foundation regula­ experiences, they should be carried on tions requiring advance notice of all and evaluated in accordance with pre­ operations. But advance notice may scribed methods of project design, not be enough; in some cases it may analysis, etc. Where government con­ be desirable to stop the interfering tractors or grantees are involved this weather modification activity. If those should not pose any great difficulty. activities are carried on by other re­ The case is different with private searchers, whether or not Federally operators where, among other objec-

110 tions, the increased cost of operation In view of the state of the art, it might be prohibitive. For the moment would seem appropriate to limit regu­ it is felt that no such requirements lation to the least amount consistent should be imposed on private opera­ with achievement of the objectives of tors, but the situation may change the program. The Commission's recom­ rapidly. In the meantime, study should mendations are deliberately restricted be given to the legal obstacles, if any, in scope. It would be well to note, to such a requirement, and the desira­ however, that as the art develops, and bility or necessity of government as weather and climate modification financing of the evaluation. activities increase, comprehensive reg­ Thus the Commission recommends ulation seems inevitable. Such regula­ that the Federal Government by ap­ tion will probably require the setting propriate legislation be empowered to: of minimum standards of competence, and perhaps financial responsibility, delay or halt all activities—pub­ for all operators and the establishing lic or private—in actual or potential of some authority for deciding be­ conflict with weather and climate tween competing claims for priority. modification programs of the Federal What the proper amount of regulation government, whether carried on by the is will depend on how rapidly the field government itself or by its grantees expands. It may be that the findings or contractors; of the NAS Panel will stimulate very immunize Federal agents, gran­ rapid expansion of field programs. The tees, and contractors engaged in regulatory program may well have to weather and climate modification ac­ keep pace. tivities from State and local govern­ Whatever regulation is decided ment interference; and upon must be national in scope. While it may be that some activities will provide to Federal grantees and have effects limited to the boundaries contractors indemnification or other of a particular State, it seems likely protection against liability to the pub­ that such cases will be exceptional. lic for damages caused by Federal Whether there will be any need for or programs of weather and climate utility in simultaneous regulation by modification. 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 effec- Such 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 regu­ grams, 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 prohibi­ tion bill recently vetoed by the Governor of Penn­ sylvania 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 detrimen­ tal to a county's welfare.

112 The major impulse behind the de­ at which the seeding agent is intro­ WEATHER velopment of a national program of duced into the atmosphere—clearly weather modification arises in asso­ far enough in some instances to cross ciation with problems encountered national boundaries. The probability MODIFICATION within the United States. Efforts to of success in such activities is now develop or apply weather modification sufficiently high to warrant immediate AND techniques on the part of governmen­ attention to their implications for in­ tal agencies, research institutions and ternational relations. The possibility commercial enterprises have focused of downstream diminution of rainfall INTERNATIONAL mainly on domestic problems and —though small—cannot be completely have been carried out primarily within ignored, with even greater implica­ the borders of this country or over the tions for international problems in RELATIONS open seas. It might seem, therefore, equitably sharing a natural resource. that weather modification had little to If the political problems are suffi­ do with international relations or con­ ciently near at hand to suggest Fed­ siderations of foreign policy. This eral, rather than State, regulation would, however, be an erroneous view. domestically (see the chapter in this The active interest in the subject dis­ report on Legal and Legislative As­ played in foreign countries and in in­ pects), it is not too early to give some ternational organizations, the interna­ attention to the international political tional impact of projected research problems and opportunities. and operational programs and the con­ Rudimentary attempts have already tribution which a weather modification program could make to the foreign As a basis for the preparation of this policy objectives of the United States chapter of the report, members of the Com­ mission, in addition to reviewing the limited are indicative of the international im­ literature bearing upon the subject, con­ plications of this area of scientific sulted with a number of government offi­ effort. cials and persons in private life experienced in international affairs and particularly in­ The evidence before us suggests ternational scientific programs. The Com­ that attempts to augment rainfall over mission also obtained a report on interna­ areas of a few thousand square miles tional relations and weather modification from Leonard E. Schwartz of Operations may have effects that may extend and Policy Research, Inc. of Washington, many miles downstream from the site D. C. See the Appendix.

113 been made to influence the intensity of alteration will take place in the atmos­ hurricanes over international waters. phere over some other region. Although no success has been claimed, There is the very long-range matter the probability of success in future of influencing the world-wide climate attempts is somewhat greater than either by conscious intervention zero. A similarly small probability of through exploitation of triggering success will be applicable to attempts effects or inadvertently as the multi­ to influence the direction of move­ farious activities of an expanding ment of a hurricane when those at­ population exert an ever more pro­ tempts are made. Not much imagina­ found influence on man's natural en­ tion is required to envision the kind vironment. In the latter case, issues of international political problems that arise that transcend national consid­ might ensue should those small prob­ erations and affect all mankind. abilities of success be realized. Even graver problems, though much The salient points can be summarized: more remote, arise in the matter of For each identifiable class of possible modification of the climate meaningful modification of weather over areas of subcontinent size. The or climate (e.g., dissipation of super­ fundamental unity of the global atmos­ cooled fog, augmentation or redistri­ phere and the close coupling and in­ bution of rainfall, suppression of hail, teraction that exist among the major altering the intensity or causes of hur­ components of planetary wave are ricanes, large-scale modification of cli­ well recognized characteristics of the mate), there exists a probability of atmosphere. The situation in which a success. The probabilities range from drought of many months duration in very high for supercooled fog through one section of the United States occurs something greater than 50 percent for concomitantly with above normal rain­ rainfall, down to very low but greater fall in another section can be general­ than zero for large-scale climate ized. If one day it turns out to be effects. possible to exercise meaningful modi­ The implications for international fication of the weather or climate over relations of success in each class of one region of the earth's surface it is weather and climate modification de­ quite possible that a compensating pend on the particular class in ques-

114 tion. For example, the implications are tral role. Such large world-wide pro­ minor in the case of supercooled fog, grams of scientific research as the quite significant for rainfall, large for International Geophysical Year (ICY) hurricanes, and very large indeed for and the International Years of the world climate. Quiet Sun (IQSY) have not only wid­ 3. In contrast to the situation exist­ ened man's knowledge of the factors ing a decade or so ago, now at hand bearing upon the atmosphere and con­ are the scientific and technological sequently weather and climate, but tools to explore the limitations and have also demonstrated new and practical applications of each class of imaginative patterns of international activity. cooperation. The United States Government has for some years participated in bilateral INTERNATIONAL PRODRAMS cooperation with other governments in the field of meteorology with em­ RELATED TO WEATHER phasis upon . The agreement with the Soviet Union an­ MODIFICATION nounced in October 1964 for the ex­ change of meteorological satellite data International cooperation in the between Moscow and Washington study of the earth's atmosphere has over a special twenty-four hour com­ been carried on for many years munications link is one of the most through both governmental and pri­ recent and interesting examples of this vate agencies. Official international bilateral cooperation. An example of activities in this field have been cen­ bilateral cooperation having world­ tered in the World Meteorological wide ramifications is the TIROS Organization (WMO) established in weather satellite program developed 1947 primarily in connection with the by the U. S. Weather Bureau and the collection of weather data for fore­ National Aeronautics and Space Ad­ casting purposes. In the non-govern­ ministration. Under this program the mental area, the International Council United States is now making available of Scientific Unions (ICSU) and its valuable meteorological data collected constitutent bodies have played a cen- by a TIROS satellite and immediately

115 transmitted to receiving stations in through the ICSU are closely related, foreign countries over a specially de­ in that the projected system of data vised communications system. collection and processing will serve Multilateral international activities the purposes of both. more directly related to the problems Weather modification is thus inti­ of weather modification were stimu­ mately related to the broader program lated by President Kennedy's speech of international collaboration in the to the General Assembly of the United atmospheric sciences which has Nations in , in which emerged during the last three or four he appealed for international coopera­ years and which consists of the fol­ tion in the peaceful uses of outer lowing four main elements: space. The Assembly responded by The program of atmospheric re­ adopting Resolution 1721 (XVI) in search now being planned in the World December of that year, Part C of which Meteorological Organization and the contained recommendations for ad­ Inter-Union Committee on Atmos­ vancing the state of the atmospheric pheric Sciences of ICSU; sciences with a view to determining The World Weather Watch being the possibility of large-scale weather developed through the World Meteor­ modification and for developing an ological Organization; improved system of weather forecast­ A climatological program aimed ing. The principal responsibility for at an improvement in the description carrying out the necessary studies and of world-wide climate with a view to planning with respect to weather fore­ facilitating the better utilization of casting was placed upon the WMO, land and water resources and ulti­ while ICSU was subsequently invited mately contributing to the objective to formulate additional suggestions of modifying climatic conditions. for advancing research in the atmos­ Strengthened educational pro­ pheric sciences. The development of grams to provide the scientific and the improved world weather system technical manpower required for the (subsequently named the World overall program. Weather Watch) through the WMO The scientific community of the and of the basic research program United States has played a major role

116 in the formulation of this program and and climate modification with a strong is continuing to do so. Moreover, the emphasis upon international coopera­ U. S. Weather Bureau has had a prom­ tion. To be sure, much of the research inent part in the development of plans to be undertaken will be carried out for the World Weather Watch and the within the borders of the United program of atmospheric science re­ States. Nevertheless, the extensive and search being developed by the WMO. significant work that is being done in The interchange of ideas and the close other countries underscores the need collaboration that has been effected for promoting the international ex­ between scientists in the government change of data and research findings and in private institutions—and be­ for the purpose of maximizing their tween those primarily engaged in re­ usefulness. The need for international search and those occupied in govern­ collaboration in the actual planning mental weather services—have proved and conduct of research activities may important in reflecting the views of a be expected to increase as research broad cross-section of the scientific moves out of the laboratory and into community and in assuring that the the realm of field experiments asso­ requirements of both research and ciated with the study of the dynamics operations receive proper and ade­ of climate, the establishment of a quate attention. It is hoped this com­ global weather observation network plementary relationship will continue (which supports the numerical simu­ not only on a national but also on an lation program) and the investigation international level. of other aspects of the general atmos­ pheric circulation. Proposals for re­ search already advanced, such as those INTERNATIONAL REQUIREMENTS involved in the World Weather Watch, involve a reliance upon widespread OF RESEARCH international collaboration in data col­ lection. They require the selection of The broad program of research out­ areas of study far removed from the lined in earlier chapters of the Com­ United States, such as land and sea mission's report demonstrates the need areas in the southern hemisphere and for approaching problems of weather the polar regions. Both the basic

117 knowledge gained in such investiga­ international complications heretofore tions, and its practical application to avoided. weather forecasting and weather and climatic modification, will be of great interest to many countries. The tech­ WEATHER MODIFICATION AND nological and human resources re­ quired for the conduct of this type of WORLD POLITICS research are far beyond the capability of most countries to provide individ­ In the present stage of world affairs ually. Increased international collabo­ any scientific advance contributing ration in such endeavors would seem, significantly to man's ability to affect therefore, to be inevitable. the natural environment has a bearing Looking into the future to the time upon the political relations among when field experiments with weather states and the quest for peace and or climate modification are expanded security. The importance to military in scope and number and involve ac­ operations of a capability for modify­ tual attempts to introduce changes in ing local weather conditions is obvious. the atmosphere, some form of inter­ Moreover, in view of its potentially national collaboration will be essential spectacular character and its impor­ in the planning and execution of proj­ tant consequences for the welfare of ects that may have an impact not only all nations, a capability for significant upon the immediate localities but on weather modification would augment areas in other countries and even upon the prestige and political influence of other continents distant from the scene the country which first achieved it. of work. It is possible situations of Nor can it be overlooked that an this sort may arise in the near future ability to control weather conditions if an expanded program of field ex­ could have an effect upon international periments in cloud seeding is under­ conflicts apart from the range of taken in areas near the northern or strictly military operations. The effec­ southern borders of the United States. tive precipitation of water from mois­ An expansion in experimentation with ture-laden clouds over the territory of tropical hurricanes may also present one State to the real or imagined detri-

118 ment of an adjoining State normally The challenge and the opportunity dependent upon the same sources of presented to the world community by atmospheric moisture, could easily the prospect of man's achieving the serve to stir up international contro­ ability to modify the atmospheric en­ versies and exacerbate existing ten­ vironment form one of the most excit­ sions. Even the remote possibility that ing long-range aspects of the subject. a nation might develop a capability of It involves the possible acquisition of using weather modification measures a new and enormous power to influ­ to damage the economy and civil ence the conditions of human life. The population of another country must potentialities for beneficial application be recognized. are vast, as are also the potential dan­ gers. It is in the long run essential to develop political and social controls RELATION TO U.S. FOREION POLICY over the use of this power which will maximize the opportunities for its con­ It should be clear that a long-range structive, peaceful use and minimize program of weather and climate modi­ the factors which tend to involve it in fication can have a direct bearing upon the tensions and conflicts inherent in the main purposes of American foreign human society. policy. It can contribute to defending The very fact that the development the security of the United States and of a capability for influencing the at­ other nations of the free world. It can mospheric environment is still in its aid the economic and social advance­ infancy should widen the opportunity ment of the developing countries, presented by this scientific endeavor many of which face problems asso­ to develop attitudes and patterns of ciated with adverse climatic condi­ collaboration which can contribute tions and serious imbalances in soil not only to the achievement of the and water resources. It can serve as practical technological goals, but also a new and widening area for the de­ to the relaxation of international ten­ velopment of common interests with sions. Vested national interests in both friends and present adversaries, technological achievement in weather and thus stimulate new patterns of modification are still limited. In con­ international cooperation. trast to the field of atomic energy and

119 developments in outer space, no nation ulated by a series of dry years in the has yet forged a weapons system in United States, will no doubt produce the field of weather or climate control a greatly enlarged interest and activity that can threaten the security of an­ in connection with weather modifica­ other country. Moreover, while politi­ tion. Field experiments conducted both cal influences have by no means been by governmental and private agencies totally absent in even the restricted may be expected to expand. Commer­ international programs that have so cial operations may well increase. far been initiated in the atmospheric Larger public appropriations for sciences, no major political issues weather and climate modification pur­ have yet been raised on which rigid poses will be sought and probably and irreconcilable positions have been made. Legislation dealing with various taken. Small beginnings in collabora­ aspects of weather and climate modi­ tion on problems of weather and cli­ fication will be considered and prob­ mate have already been made which ably be enacted. could prove useful in helping to build An expanded United States activity the habit of cooperation and in stimu­ in weather and climate modification lating a pragmatic recognition of the cannot fail to have its impact upon material advantages to be derived from governments and public opinion in that approach. other countries. Questions will arise as to the exact level of capability achieved by the United States in affect­ INTERNATIONAL IMPACT OF ing weather; the potential benefit or U.S. PROORAM danger which this power to influence the atmosphere may imply for other The growing recognition of the effi­ countries; and the policies and pur­ cacy of certain cloud-seeding practices, poses that will guide the United States coupled with an increased public de­ in the development and exercise of mand for rain-making operations stim- this new technology.

120 ities of this sort by the various inter­ ORGANIZATION OF ested agencies and organizations INTERGOVERNMENTAL through both bilateral and multilateral channels of contact with foreign coun­ COOPERATION tries. The policy decision should also lay the basis for the planning of future programs and the anticipation and The responsibility for promoting inter-governmental cooperation and study of problems associated with the contacts on the scientific and techni­ international aspects of modification cal level with respect to weather and activities. climate modification be recognized in The Commission endorses support whatever administrative arrangements by the United States of the World are decided upon for the national pro­ Weather Watch and the program of gram in this field. The close relation­ research in atmospheric science being ship of weather modification to other planned by the WMO and ICSU. As programs and responsibilities of the a further measure of international co­ government would, of course, require operation, the Commission urges that an adequate system of inter-agency if a national laboratory is established, coordination in connection with it be given a mandate to promote the United States participation in interna­ wide participation of foreign govern­ tional weather and climate modifica­ mental and private institutions in the tion activities. development of research programs of The formal adoption of a policy of international interest. The successful international cooperation for the execution of this function by a United peaceful development of weather and States national institution might pave climate modification would confirm the way for the future establishment and support the limited but significant on a truly international basis of one cooperation now being extended by or more centers devoted to the co­ governmental and private agencies of operative study of the atmosphere and the United States in this field. It should its intervention in the interests of hu­ provide an impetus for further activ- man welfare.

121 lems may well be encountered in many SCIENTIFIC AND TECHNICAL of the less developed countries where EXCHANOE the natural environment and patterns of economic and social life present In the basic field of international contrasts to those prevailing in this exchange of information and technical country. A greater understanding of cooperation several problems present the significance of these differences themselves. A major limitation affect­ must precede any attempt to evaluate ing both advanced and developing the suitability of various weather countries is the shortage of trained modification practices for specific for­ personnel in atmospheric sciences at eign areas and to design appropriate all levels. The growing discrepancy programs of cooperation. The oppor­ between the advanced and developing tunity for international cooperation in countries in this respect imposes a such research programs is obvious. further obstacle to genuine interna­ tional cooperation. Attention should be given to the question of how greater emphasis can be given to atmospheric INTERNATIONAL LEDAL PROBLEMS sciences in existing bilateral and mul­ tilateral programs of education and Some form of international regula­ technical cooperation, and to what tion of weather modification activities additional measures may be needed will no doubt become essential in the to fill any deficiency. future as research and operational Encouragement should also be given activities increase in number and ex­ to the development of basic research tent. One forum for the international on the impact of weather modification consideration of legal aspects of this measures in foreign countries. Other problem, insofar as they concern ac­ chapters of this report have indicated tivities in outer space, already exists the need for greater attention to the in the legal subcommittee of the Com­ biological and economic and social mittee on Peaceful Uses of Outer Space aspects of weather modification in the of the United Nations General Assem­ United States. A different set of prob- bly. Little attention has yet been given,

122 however, to such basic questions as voluntary coordination of national the proprietary rights of states to the programs. Whether the assignment of atmosphere passing over their terri­ operational responsibility to an inter­ tories; the liabilities of states for national agency should be considered damage inflicted upon the adjoining for the future deserves thought even states as a result of deliberate or in­ at this early date. What new concepts advertent tampering with the atmos­ of international organization suggest phere; or procedures for advance themselves for that purpose and what notification or consultation regarding new problems of a technical or politi­ projected weather modification meas­ cal nature would be precipitated by ures capable of affecting other states; such a plan? Considerable light may etc. If international regulations are be thrown on these questions by the formulated, the whole question of en­ experience to be gained in the global forcement likewise comes to the fore. observation program now being planned in connection with the World Weather Watch. QUESTIONS OF INTERNATIONAL Steps should be taken by the United States, in concert with other nations, ORGANIZATION to explore the international institu­ tional mechanisms that may be appro­ Looking even farther ahead, thought priate to foster international coopera­ must be given to the types of interna­ tion and cope with the problems which tional organization that will be needed, may be anticipated in the field of and the functions they should per­ weather and climate modification. The form, if and when operations in United Nations and its specialized weather and climate modification af­ agencies (e.g. the World Meteorologi­ fecting large continental areas become cal Organization) is suggested as a feasible. At present international or­ possible governmental framework. The ganizations in the field of atmospheric International Council of Scientific sciences are of the traditional, general Unions and its associated unions (e.g. membership variety with limited func­ the International Agencies of Geodesy tions of information exchange and and Geophysics) could be a suitable

123 non-governmental framework for Government of the United States, in these mechanisms. connection with the expansion of its Rarely has a more inviting oppor­ program of weather and climate modi­ tunity been offered for advance think­ fication, to issue a basic statement as ing and planning regarding the impact to how it views the relationship of this of a technological development upon new national effort to the interests, international relations. It is hoped that hopes and possible apprehensions of government agencies, universities, re­ the rest of the world. The Commission search institutes, centers of interna­ further believes that emphasis upon tional studies, societies of international international cooperation in the devel­ law, as well as individuals will take opment of weather and climate modi­ advantage of this possibility of con­ fication programs will contribute sub­ tributing to the maximum utilization stantially to scientific and technical of the anticipated capability of affect­ progress and will also serve the na­ ing weather and climate in the inter­ tional purpose of seeking to build a ests of peaceful world development. peaceful world order. Progress in the diminution of inter­ The Commission recommends the national tensions and the achievement early enunciation of a national policy of peace will come not so much from embodying two main points: 1) that it the dramatic resolution of basic inter­ is the purpose of the United States, national controversies as from the far with normal and due regard to its own less spectacular growth in ways of co­ basic interests, to pursue its efforts in operation and from the widening of areas of mutual interest among rival weather and climate modification for nations. peaceful ends and for the constructive improvement of conditions of human life throughout the world; and 2) that RECOMMENDEO BASIC POLICY the United States, recognizing the interests and concerns of other coun­ STATEMENT tries, welcomes and solicits their cooperation, directly and through The Commission believes that it international arrangements, for the would be highly desirable for the achievement of that objective. This

124 cooperation should cover both re­ weather and climate. Such a policy search and operational programs of declaration could be issued by the interest to other countries. It should President or incorporated in any basic be concerned not only with deliberate legislation on the subject of weather but also inadvertent human interven­ and climate modification which the tions in the atmosphere that affect Congress may enact.

125 FEDERAL FINANCIAL SUPPORT OF Federal Funding of Weather Modification Prrams FUNDINO AND WEATHER ANO CLIMATE Millions of ADMINISTRA. MODIFICATION Dollars 8

- * 1962 Peak due to l.ómillion increment by ARPA TION Present Support o Actual The chart set forth below shows REQUIREMENTS that with the exception of FY 1962 the total Federal government support of agency research and development pro­ grams in weather and climate modi­ fication remained at about the same level during the first 5 years after the initial funding of the National Science 2- Foundation program in FY 1959 and increased at the rate of 35-407o per 3 fiscal years. o year in the last 59�60�61�62�63�64�65�6

FISCAL YEAR

Source: National Science Foundation

126 ���

The table below displays the last�weather modification research estab- fiscal year 1965 and the current fiscal�lished by the Interdepartmental Corn- year 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 Federal Funds for Atmospheric agencies reported to ICAS budget Sciences and Meteorological totals of $4.93 million for FY 1965 and Services $7.19 million for FY 1966 in direct sup­ (millions of dollars) port of weather modification. FY 1965* FY 1966 For purposes of understanding the Aeronomy�110.7�111.3 relationship of the current support Meteorology�98.3�116.0 for weather and climate modification Total Atmospheric Sciences *� research to the support for the over­ 209.0�227.3 all scientific research programs and Total Meteorological Services **�261.2�273.3 services of which it is a part, there Grand Total are set forth below tables displaying Atmospheric the FY 1965 and 1966 total Federal Sciences and budget for atmospheric sciences and Meteorological meteorological services. Services�470.2�500.6

* Source: Interdepartmental Committee for Atmospheric Sciences ** Source: Office of the Federal Coordinator for Meteorological Services and Supporting Research

128 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 Need ior increased suppom to $30 million per year by FY 1970.' Additional amounts will be needed for lot Research, Deveiovmeni, underlying basic research activities and the provision of large computing and operanons facilities. This recommendation is in recogni­ The Commission recommends that tion of the uncertainties in the state of the total current FY 1966 budget for knowledge and potentialities in the climate and weather modification re­ field of weather and climate modifica­ search of approximately $7.2 million tion and the diversity and magnitude be increased by 1970 to $20 to $30 of effort required to exploit the possi­ million or approximately 5% of the bilities which have been discussed total current FY 1966 budget of $500.6 elsewhere in this report. Weather and million for both atmospheric sciences climate modification research should and meteorological services. Addi­ now have a more important role in tional increases of the same order are research and development in the at­ needed for basic research and for large mospheric sciences. Large, scientifi­ computing facilities, making for a total cally designed and controlled field increase of $40 to $50 million per year experiments are needed. Associated by 1970. biological and social science research is desirable to measure the effects of At present weather and climate modification research represents less 'These figures include applied research than 2% of the current budget for the and immediately supporting basic research for increasing precipitation by seeding, sup­ scientific research programs and serv­ pression of lightning and hail, fog and cloud of which it is an integral part. dispersal and severe storm modification. The foregoing recommendation would They do not include the longer range basic research studies required for assessment of mean that the total budget for weather advertent and inadvertent modification of and climate modification research climate.

129 experiments on the ecological and One can not comment conclusively social systems. Required also are on the required nature, organization costly logistics support, aircraft, in­ and financing of the new research and strumentation, larger computers, lab­ development enterprise described oratory models of the atmosphere, and here. The need is clear; the question perhaps synchronous satellites and is how. The President's Special Assist­ ecology laboratories. ant for Science and Technology might wish to initiate the appropriate feasi­ The Commission recommends that bility studies as to the nature, precise a new research and development ca­ functions, and location of the new pability be established—similar per­ enterprise. haps to a national laboratory—for the purpose of providing the necessary resources of scientific leadership and ADMINISTRATION logistic facilities necessary in the mounting of an expanded interdisci­ plinary program of weather and cli­ Existing Statutory and mate modification. A11101HISIFaIlVe oirecoves A national laboratory type of capa­ bility is needed which could form the a. Coordination of Scientific Policy organizational and scientific man­ power nucleus for an expanded re­ Both the Federal Council on Science search and development program. The and Technology and the National costs of such a capability are not in­ Science Foundation have responsibili­ cluded in the foregoing estimates and ties with regard to scientific policy on recommendations. The organizational weather modification research and structure for this capability should operations. The Federal Council, un­ provide machinery for assuring an der the Chairmanship of the Science interdisciplinary approach to weather Advisor to the President, is given and climate modification—encompass­ general coordinating responsibility for ing the physical, engineering, biologi­ science policy within the executive cal and social sciences. branch of the Government. This au-

130 thority is provided both by Reorgani- the legislative history thereof, the zation Plan No. 2 of 1962 and Execu- Foundation was expected to take the tive Order 10807 of March 13, 1959. lead among the various Federal de­ The Federal Council, under the pro­ partments and agencies in the support visions of Executive Order 10807, is of weather modification research. The charged with the following responsi­ Foundation complied by supporting bilities: sponsored research which provided Sec. 2. Functions of Council (a) The the underpinnings for the more mis­ Council shall consider problems and sion oriented programs of other agen­ developments in the fields of science cies. The Foundation established and and technology and related activities has continued an annual Interagency affecting more than one Federal agency Conference on Weather Modification, or concerning the overall advancement which has become a focus for govern- of the Nation's science and technol­ ment-wide program planning and co­ ogy, and shall recommend policies and ordination. other measures (1) to provide more At about the same time that the effective planning and administration Federal Council for Science and Tech­ of Federal scientific and technological nology was established in 1958, the programs, (2) to identify research National Science Foundation recog­ needs including areas of research re­ nized the need for a formal interagency quiring additional emphasis, (3) to coordinating mechanism in connection achieve more effective utilization of with its newly assigned statutory re­ the scientific and technological re­ sponsibility in the field of weather sources and facilities of Federal agen­ modification by establishing an Inter­ cies, including the elimination of departmental Committee on Weather unnecessary duplication, and (4) to Modification. During the June 1959 further international cooperation in meeting of the Federal Council there science and technology. was discussion concerning the estab­ The Advisory Committee on lishment of a Committee to cover the Weather Control recommended that field of Atmospheric Sciences. The the National Science Foundation coor­ President's Science Advisor and the dinate weather modification research. Director of the Science Foundation Under the authority of PL 85-510 and agreed that the Foundation existing

131 Interdepartmental Committee on the Foundation and other agencies Weather Modification could serve the have become significant supporters of needs of both the Federal Council and research in the social, as well as the the Foundation. As a result, the Inter­ natural sciences. departmental Committee on Weather Research is supported not only to Modification was formally reconsti­ accomplish agency missions—usually tuted as the Interdepartmental Com­ as a forerunner to development—but mittee for Atmospheric Sciences also to increase the broad body of (ICAS) and held its first meeting as scientific and technical knowledge such on September 9, 1959. which underlies the future advance­ Thus, general coordination on be­ ment of the Nation's welfare, economic half of the President's Executive Office growth, and security. This is particu­ with regard to research in this and larly true of basic research conducted related fields is exercised by one of primarily in academic institutions but the committees of the Federal Council also in government, industrial, and on Science and Technology—the Inter­ other laboratories focusing on funda­ departmental Committee for Atmos­ mental problems in science. pheric Sciences (ICAS). Within ICAS The President's budget for FY 1966 is a panel on weather modification contemplated an outlay of $14.5 bil­ research which is chaired by the Head lion for research and development of of the Section on Atmospheric Sci­ which $4.9 billion was estimated for ences of the Foundation. research and of which $2 billion is for basic research. b. Support of Research by Indi­ Executive Order 10521 issued in vidual Agencies March, 1954 and amended in March, 1959 provides that: Since 1940 the Federal Government Sec. 4. As now or hereafter author­ has assumed an increasingly impor­ ized or permitted by law, the Founda­ tant role in the financing and conduct tion shall be increasingly responsible of scientific research and development for providing support by the Federal in this country. This has been espe­ Government for general-purpose basic cially true in the natural sciences and research through contracts and grants. engineering. In recent years, however, The conduct and support by other

132 Federal agencies of basic research in motes the exchange of information areas which are closely related to their about the plans and programs of the missions is recognized as important various Federal agencies and provides and desirable, especially in response for cooperation and coordination at to current national needs, and shall the working level through various continue. mechanisms, including the annual In other words the Foundation is Interagency Conference on Weather charged with the support of basic re­ Modification, where much of the cur­ search across the board and individual rent Federal interest in weather modi­ agencies are authorized to conduct fication has been kindled. and support such basic research as is Despite the broad statutory lan­ necessary to sustain their operational guage cited above, the Foundation has missions. elected to confine its research activ­ ities to basic research, generally of c. Conduct of Weather Modifica­the type that the Foundation would or tion Research Programs could have supported anyway under its general authority to support basic 1. National Science Foundation research in the sciences. The Founda­ Public Law 85-510 directs the Foun­ tion selected as the first necessary task dation "to initiate and support a pro­ the development of a sound scientific gram of study, research, and evaluation basis for the art of weather modifica­ in the field of weather modification, tion. The stature of the Foundation giving particular attention to areas gave creditibility to a field which had that have experienced floods, drought, been plagued with a lack of technical hail, lightning, fog, tornadoes, hurri­ and scientific understanding. The canes, or other weather phenomena, Foundation approached the leading and to report annually to the President meteorologists and other scientists and the Congress thereon." The Foun­ with financial support to undertake dation's responsibility is therefore not scientific investigations to open the only to support weather modification doors of knowledge. research, but to present an overview The research-support program is of the state of knowledge and effort managed as an integral part of the in weather modification. It also pro- Foundation's over-all program of in-

133 vestigation in the atmospheric sci­ understanding to commit the proposed ences. The dividing line between re­ model to theoretical analysis. search in weather modification and Foundation support for weather basic research in the atmospheric sci­ modification research in 1965 totaled ences is difficult to draw, especially $2.0 million for 28 projects. The At­ when so much more fundamental mospheric Sciences Program of which knowledge is required to provide the weather modification is a part has scientific basis for a successful na­ grown from $2.9 million in FY 1959 tional program for developing new to $23.2 million in FY 1965. and improved weather modification Under PL 85-510 research programs techniques. conducted by the Foundation were Through grants with key university rather expected to include cooperative groups and through the contract sup­ programs with States. By implication port of the National Center for Atmos­ the Foundation was directed to en­ pheric Research (NCAR) the Founda­ gage in applied research and develop­ tion has given special emphasis to ment as well as basic research with studies on the development of models regard to weather modification. Addi­ to describe the natural processes tionally, the Foundation was author­ which produce the clouds, the weather, ized to obtain by regulation or other­ and the general circulation of the at­ wise information it deems necessary mosphere. Many problems confront to its program of study, research and the designer of such a theoretical evaluation in the field of weather model, among which are the inade­ modification. The statute also directs quate observations of natural phenom­ the Foundation to give particular at­ ena to establish the proper theoretical tention to geographic areas which are approach. It is difficult to determine afflicted with recurring damage from how natural atmospheric phenomena weather—flood, drought, hail, etc. may be made accessible to human intervention, and it is also difficult to (2) Department of Commerce assess the results of such intervention. The Weather Bureau, a part of the The burden is therefore placed on the Environmental Science Services Ad­ theoretician to make sufficient prog­ ministration (ESSA), has initiated a ress in raising the level of physical basic and applied research program in

134 the field of weather modification, hold­ natural processes which produce the ing that this type of activity is con­ weather and circulation of the atmos­ sistent with and necessary to the ac­ phere. Special attention is being given complishment of the basic mission of to research dealing with the interac­ the Weather Bureau—namely, the pro­ tions at the ocean-atmosphere surface. vision of increasingly accurate fore­ In a recent report to the President, casts and warnings of weather and the Secretary of Commerce recom­ flood conditions. mends an enlarged national program Experiments on tropical clouds and of weather modification and states his hurricanes are conducted jointly with intention that the Environmental Sci­ the Navy under Project STORMFURY. ence Services Administration (com­ The clouds are studied in relation to prising the Weather Bureau, Coast and the hurricane system and as they op­ Geodetic Survey and related agen­ erate during undisturbed weather con­ cies) take a leading role in such a ditions. The technique used to explore program. the cloud mechanism has been silver iodide seeding using pyrotechnic de­ (3) Department of Defense vices called Alectos; a broader ex­ perimental program is planned for the The Department of Defense has con­ future. The project is in the research sistently carried on an active pro­ phase, and experimental operations gram of weather modification research have been performed to probe the as weather phenomena related to re­ mechanisms involved in convective spective military missions of the three motions in cumulus clouds over the services. These are described below. ocean. Scientific experiments on the large-scale atmosphere appear to be (i) Air Force necessary before the reduction of the The program of the Air Force in severe storm hazard by manmade con­ cloud physics is centered around the trol of convective phenomena can be activities of the Air Force Cambridge realized. Research Laboratories at Hanscom Development of theoretical models Field, and is directed towards a study is continuing which are capable of of the life cycle of clouds, utilizing reproducing and accounting for the ground radar and highly instrumented,

135 cloud-physics aircraft. Observations urements of the significant meteoro­ are made of the atmospheric electri­ logical parameters utilizing a micro- cal properties in the vicinity of the meteorological tower and a cloud- cloud environment which are coupled physics research facility on the base. to the refractive index measurements An 11-station mesometeorological net­ before, during, and after cloud pene­ work extending over the southwest or tration. The dynamics of clouds are upwind section of the Cape was also studied by both aircraft penetration placed in operation. A disdroin­ and by stereo ground-camera net­ eter, for measuring droplet size, is works. This work is supplemented by among the new instruments which laboratory studies of the micro-physi­ were developed especially for this cal properties of clouds. A cumulus program. More data from this program cloud observational program is carried was gathered during 1965 and are now on in Florida during the summer being reduced and analyzed. months to obtain information on cu­ mulus growth and precipitation. (ii) Army In an effort to establish a sound scientific basis for the development of Research in weather modification fog forecasting and fog-modification has been centered primarily around techniques, the Air Force has under­ the Army Electronics Research and taken a comprehensive field research Development Laboratories in New program to characterize and under­ Jersey and their contractors. The ob­ stand the natural life cycle and vari­ jective of the Army research program ability of warm fog. The program has is to obtain a better understanding of been nicknamed Project CATFEET. the physical concepts of rainmaking. Cape Cod, Mass., was selected as the Activity has been centered in three site for this research, with Otis Air particular areas of effort; namely, the Force Base being the main instru­ basic studies of cloud physics mecha­ mented facility. The first data were nisms, the basic understanding of pre­ obtained at this site during July and cipitation phenomena, and the basic August of 1964. The formation, de­ concepts of modification. On the velopment, and dissipation of the fog whole, work in cloud physics has been was documented by intensive meas- concentrated upon convective cloud

136 systems. A program of thunderstorm measure the water content and cloud- research was conducted during the droplet size distribution in clouds. summer in the area of Flagstaff, Ariz., Studies of the origin and nature of where basic cloud mechanisms were cloud condensation nuclei and of the studied which might provide possible role of nuclei in cloud and fog forma­ applications to the modification of tion, stability, and precipitation, and cumulus-cloud dynamics and nuclea­ Exploration of the feasibility of tion. A small program has been car­ using tracer techniques to study cloud ried out in the areas over the Great motions and the interchange between Lakes, where a considerable amount a cloud and its environment. of snow is usually obtained. An effort Work in weather modification being was made to learn more about the performed at the Naval Ordnance Test temperature inside clouds by studying Station at Lake during 1964 has the formation of ice crystals after been in the field of development of seeding with dry ice. Other studies means for changing weather and cloud have included nuclei counts within conditions for tactical purposes. Re­ clouds, the collection of raindrop sponsibilities for planning and co­ spectra, comparison of raindrop size ordination of naval activities in the at different wind speeds, and the co­ environmental-control research area alescense of raindrops. has been assigned to the Navy Weather Research Facility located at Norfolk, (iii) Navy Va. Included in the current program already underway are the following: The efforts by the Navy in weather (a) The use of the operations re­ modification are centered around two search approach to speed up the phenomena: warm fog and trade winds eventual applications of environmental cumulus clouds. The principal labora­ control in naval operations. (b) Con­ tory and field work is carried out by sideration of the applications of cur­ scientists attached to the Naval Re­ rent and potential weather techniques search Laboratory. Work is in progress in the support of naval operations. along three general lines: (a) Develop­ (c) Planning and coordination of the ment of aircraft instruments possess­ Navy portion of the Project STORM­ ing fast response and accuracy to FURY program.

137 (4) Department of Interior of the artificial seeding of clouds by Due to the interest by some mem­ the Humboldt River Basin and an in­ bers of Congress (principally from creased effort at South Dakota School western States) in an aggressive pro­ of Mines and Technology. gram of weather modification, the Bu­ To manage and coordinate the pro­ reau of Reclamation has been directed gram an Office of Atmospheric Water through appropriation language to in­ Resources was established in Denver, augurate a weather modification re­ Colorado. A small group of engineers, search program with emphasis on the meteorologists, and administrative engineering aspects. The program was personnel have been assigned to staff started during FY 1962. It is directed this new office. The program will be toward learning if it is possible to in­ conducted largely as a contract activ­ crease inflow into the Bureau's reser­ ity of the Bureau of Reclamation. voir system. The Department of the Interior's in­ (5) Department of Agriculture terest in weather modification is con­ The of Project SKY­ cerned with the atmospheric water FIRE represents the primary effort of resources of the Nation and the possi­ the Forest Service in the area of bility that weather modification will weather modification during FY 1964. supply additional precipitation and Project SKYFIRE is a research study runoff to the river basins which feed on the electrical nature of thunder­ the Bureau of Reclamation reservoirs. storms and the relationships of forest Planning within the Bureau of Rec­ fires resulting from cloud-to-ground lamation points to a possible 25-year lightning charges. Attempts are being program. The Bureau program is made to modify in founded in part on the continuation ways that will decrease the number of a number of programs initially de­ and intensity of cloud-to-ground light­ veloped under Foundation sponsor­ ning. The project has two long-range ship which have now matured to the objectives: (a) To obtain a better un­ point where engineering research can derstanding of the occurrence and be established. Examples include con­ characteristics of lightning storms and tinuation by the University of Nevada lightning fires in the northern Rocky

138 Mountain region; and (b) to investi­ sive research program covering both gate the possibility of preventing or research and development. The Foun­ reducing the number of lightning fires dation has felt until the last year or by applying techniques of weather two that the state of the art dictated modification. a more conservative approach. The re- The Department plans to continue suit has been that the Foundation's the study of the relationship between efforts have largely been in the award lightning discharge and forest-fire ig­ of grants for research in atmospheric nition. Points to be considered are the sciences of a type that could have characteristics of the lightning stroke been made under the basic authority which produces ignition. In some of the Foundation in the absence of cases, lightning strokes may be pro­ the Weather Modification Act (PL longed by the bridging of several 85-510). It was also the hope of Con­ thunderstorm cells which produces gressional sponsors of PL 85-510 that more effective ignition than a shorter- the Foundation would continually ap­ duration stroke of much higher peak praise and evaluate the research under intensity. Investigation is also contin­ way in the U. S. and other countries uing on the effects of seeding upon and would provide the Congress with the electrification mechanism, and the "readings" on the prospects of weather Department hopes that some informa­ modification. The Foundation has tion will be derived as to the mecha­ largely refrained from this type of ac­ nism whereby cloud seeding will af ­ tivity on the ground that research re­ fect the buildup of charge in the sults have not been of a sufficiently thunderstorm. extensive nature that would sustain or Problems justify evaluative judgments. a. Disparity Between Congres­ b. Duplication in Research Activ­ sional Interest in Weather Modifica­ ities and Coordinative Responsibili­ tion and National Science Foundation ties Policy The legislative intent of PL 85-510 The intention of PL 85-510 was that regarding the Foundation is fairly the Foundation would carry primary clear; the Congress desired an aggres- responsibility within the Executive

139 Branch for weather modification re­ does not constitute a significant prob­ search and would assume leadership lem. Indeed, it is probably well that of the research activities of the other there be mild competition among Federal agencies in this field. For the agencies. In a field of science that is first few years, the Foundation as­ both new and critical a diversity of sumed and held the initiative, with approach is much to be preferred to respect to coordination as well as re­ a centering of responsibility, funds search. It was through the early lead­ and research direction in a single spot. ership of the Foundation that a con­ Certain aspects of weather modifica­ tinuing and orderly interchange of tion activities have now reached the research plans, proposals and findings applied research and operations phase, among the interested Federal agencies with regulatory activity not far away. was provided. In subsequent years, An expanded fundamental research as a result of the creation of the Fed­ program is now desirable and feasible, eral Council on Science and Technol­ some of which involves significant ogy with its coordinative responsibil­ logistics aspects. ity for science policy across-the-board and as a consequence of the Founda­ tion policy decision to generally con­ fine its activities to the support of some FaCIOPS AffeCling basic research on weather processes, the coordinative role initially asserted ASSIgnment ot flesponsihility by the Foundation passed to the Exec­ utive Office of the President. Within the past three years the situation re­ Following are some of the consider­ garding research activity has also ations which need to be taken into changed. Two other prominent civilian account by the National Science Foun­ agencies now "operate" in the weather dation, other Federal agencies, the research field—the Weather Bureau President, and the Congress in fixing and the Bureau of Reclamation. responsibility for weather and climate So long as weather modification ac­ modification activities. tivities are largely confined to the (1) There is need to bridge the basic research phase, this duplication organizational gap between labora-

140 tory research and large scale field ex­ istering agency so as to insure the periments; this gap can exist even in filing of information relative to all the basic research aspects. weather modification field experi­ There is need for organiza­ ments and all commercial operations. tional arrangements for enough ap­ In the absence of compel­ plied research to develop the field, ling reasons otherwise, the agency as­ while preserving scientific objectivity signed regulatory functions should in the basic research effort. The eco­ have a regional or field office estab­ nomic, political and dramatic aspects lishment. of weather and climate modification The conduct of research operations must not be permitted to and development in this field should crowd out the basic research. be kept insulated from activities in­ There is need for biological volving the regulation of weather and social science research to go hand modification operations, but at the in hand with the physical science and same time the two types of activity engineering research in support of the missions of all agencies, contractors should be sufficiently proximate or­ or grantees concerned with weather ganizationally to assure immediate ac­ modification. cess to data derived from the opera­ tions being regulated. There is need to preserve diversity in the research effort, but there is the need also to establish a Loog-Range AlleroaNves Federal organizational mechanism for accomplishing what can not be done Continuation of the Status Quo through diverse research activities. a. Responsibility should be The case for this alternative is that clearly assigned for the formulation of in a field as complex and uncertain as arrangements for appropriate scienti­ weather and climate modification, the fic cooperation with the governments best efforts of the four principal agen­ of other nations. cies now engaged in weather research Adequate enforcement are needed—Defense Department, power needs to be provided an admin- ESSA—Weather Bureau, National Sci-

141 ence Foundation, and the Department b. Assignment of Responsibility of the Interior. None of the existing for Weather and Climate Modification programs are in competition and all to the Department of Commerce of them are necessary at the present The following factors tend to favor stage of research and development. such an assignment: There is an ultimate need for a A close and inextricable more specific assignment of responsi­ connection exists among weather pre­ bility for weather and climate modifi­ diction, weather research, weather cation activities in the Government. modification and operation. Intensified Until the nature of the scientific feasi­ data collection, dissemination, evalua­ bilities are further identified, how­ tion, storage and modeling activities recommended as a key part of the ever, the direction which such an as­ weather and climate research activity signment should take is not clear. For are closely related to the weather pre­ example, if in the further develop­ diction activities of the Weather Bu­ mental phases, activity by a very reau. Understanding more about large number of aircraft, over an in­ weather and climate processes is in­ definite period is required, this logis­ dispensable both to modification and tics essential might weigh heavily in to prediction activities. favor of assigning the operational mis­ The Weather Bureau has sion to the Air Force. If, on the other the logistical capability for mounting hand, for example, it becomes neces­ weather modification operations, in­ sary to bring together large numbers cluding large scale field experiments. of university groups and commercial The Weather Bureau is a operators into a combined research logical agency to represent the U. S. Government in the intergovernmental and operational effort, the ESSA- aspects of weather modification. The Weather Bureau or the Department of Bureau has always served as the offi­ Interior with their field establishments cial United States link with the World might draw this assignment. Meteorological Organization.

142 c. Assignment of Responsibility d. Assignment of Responsibility for Weather and Climate Modification for Weather and Climate Modification to the Department of the interior to the National Science Foundation The following factors tend to favor The following factors tend to favor such an assignment: such an assignment: The phase of weather mod­ Only in the Foundation ification now most nearly ready for would the basic research aspects of aggressive applied research, develop­ weather and climate modification be ment, and actual operational activity reasonably secure from "crowding —the augmentation of precipitation; out" by operational activities. Even if —is vitally linked to the water man­ the Foundation should also carry on agement program of the Bureau of the essential developmental and oper­ Reclamation. ational activities, the agency's habits and the dedication of its staff to the Weather modification ac­ promotion of basic research would tivities including basic and applied re­ assure adequate support of the basic search relate closely to those eco­ scientific phases. nomic and political interests that are concerned with the overall mission The Foundation already has and programs of the Interior Depart­ the unique capability for providing an ment. This would go far to assure interdisciplinary approach to both the priority attention and adequate fund­ research and developmental aspects ing of the weather and climate modi­ of the function, making sure that the fication program. physical, biological, social science and engineering facets are not neglected. Weather modification ac­ This capability exists through the tivities are highly compatible with the Foundation's authority to support basic long range mission of the In­ basic and applied research in the terior Department—the conservation, fields related to weather modification. development and use of scarce nat­ The Foundation has had ural resources. seven and a half years of experience The Department of Interior in research leadership with regard to has field offices throughout the nation. weather modification. Other agencies

143 have become accustomed to looking be completely inadequate for the to the Foundation for initiative and character and the scale of the work support for weather modification re­ that will be required in the future. search. In the event of dramatic scientific progress, weather modification and e. Other Considerations climate control could very well de­ The assignment of responsibility velop into a major priority program. within the Federal Government for In this event, the program would need weather modification would be little a new governing statute and an up­ more than a routine matter of internal grading in terms of organizational sta­ government coordination were it not tus, with the possible creation of a for the fact that the entire approach new independent agency for the pur­ to the scientific and practical prob­ pose. lems of weather modification has The major alternatives in assigning recently undergone a subtle yet pro­ organizational responsibility for found change. Five years ago atten­ weather and climate modification ac­ tion was rather vaguely focused on tivities have been described. Before the physics of clouds and the possible considering possible changes in or consequences of cloud seeding. The combinations of these possibilities it development of techniques for me­ would be well to enumerate some of teorological modeling, the feasibility the factors tending to militate against of computers 100 to 1,000 times faster assignment to the agencies discussed, than those now available, and the and to consider the general problem rapidly expanding capabilities for of coordination. global observations have escalated the problem of weather and climate f. Disadvantages of Particular modification into new dimensions of Agencies scientific and technological opportun­ (1) The Reclamation Bureau is ity. limited in geographic jurisdiction to The mode of research management the Western States. Significant amend­ under which a national program has ment to its statutory authority would been conducted in the past (with its have to be made were it to undertake advantages and its shortcomings) may responsibility for weather and climate

144 modification. Also, only one aspect of The very close interrelationships weather modification —precipitation among basic research, applied re­ augmentation—is related to the over­ search, development, operations, reg­ all mission of the Bureau. These lim­ ulation, weather prediction, and the itations do not extend to the other missions of the various interested and water, land, recreation, wildlife and concerned agencies add to the diffi­ mineral functions of the parent De­ culties. The coordination problem, of partment—the Department of Interior. course, tends to be roughly commen­ The National Science Foun­ surate with the degree to which re­ dation lacks the logistical capabilities sponsibility is centralized or dispersed for developmental and operational ac­ tivities in the field, although these among the agencies. could be acquired. The Weather Bureau lacks broad authority and experience in the Cooclusloos and conduct and support through grant and contract of basic scientific re­ flecommeooatioos search, although its in-house capabil­ The Commission has considered ity in this regard has been improving carefully the problems attendant upon and extra-mural capability could be the assignment of responsibility for acquired. weather and climate modification ac­ g. Coordination tivities within the Exeuctive Branch Under no conceivable set of condi­ of the Federal Government. tions could all concern with research There are no easy solutions to these relating to weather and climate be questions. The Commission believes confined to a single agency. This leads the adoption of the following recom­ to obvious problems of coordination mendations would significantly im­ and related problems of allocation of prove the effectiveness of the Nation's resources of funds and manpower, efforts in this field, and would facili­ sharing and channeling of informa­ tate the achievement of the scientific tion, and scientific emphasis and di­ and other objecives specified else­ rection. where in this report.

145 a. Responsibility for Research, suppression by the U. S. Forest Serv ­ Development, and Operations ice; military applications by the De­ The Commission recommends: (1) partment of Defense; etc.). the assignment of the mission of de­ The degree of the Foundation's spe­ veloping and testing techniques for cial attention to this field, including modifying weather and climate to a the support of related research in single agency in the Executive Branch other affected disciplines, should be of the Government—for example to reviewed from time to time in the light the Environmental Science Services of the progress of the overall national Administration of the Department of program. The Foundation needs to Commerce or to a completely new continue the vigorous support of basic agency organized for the purpose; (2) research in the atmospheric sciences the continuance and expansion of re­ because fundamental knowledge so search in the atmospheric sciences by derived is a necessary underpinning to the National Science Foundation, in­ technological progress in weather and cluding its program directed at pro­ climate modification. viding a satisfactory scientific basis The agency assigned the mission of for weather and climate modification developing and testing techniques for and the maintenance of the National modifying weather and climate, as a Center for Atmospheric Research as a part of its overall mission, should basic research facility for this pur­ have major but not exclusive respon­ pose; and (3) the conduct or support, sibility in collaboration with the State pursuant to Executive Order 10521, of Department for formulating and such basic and applied research by implementing weather and climate other Federal agencies as is required modification programs involving inter­ for their varied missions as well as national collaboration with the gov­ the conduct of operational activities ernments of other nations. The gov­ necessary for the accomplishment of ernment's activities in international such missions (e.g., precipitation aug­ cooperation can be substantially as­ mentation for the reservoir system of sisted by the participation of the Na­ the Bureau of Reclamation; lightning tional Academy of Sciences.

146 b. Regulation A Federal agency field experiment in­ volving large-scale cloud seeding for The Commission recommends that example, can cause the same inter­ responsibility for appropriate Federal ference with other scheduled experi­ regulation of weather and climate ments as can cloud seeding conducted modification activities to aid the Fed­ eral Government's program of research by a commercial operator. and development and to protect the Consequently, Federal agencies will general public be kept separated from need to be subject to many of the research and development activities rules and regulations issued by the while assuring prompt and full avail­ type of regulatory unit recommended ability to such activities of data de­ above. Insofar as the regulation in­ rived from the regulation of commer­ volves requirements of notice of ex­ cial and other operational activities. periments, licensing of activities and Such a combination might be the like, there would seem to be rea­ achieved, for example, by assigning son why all Federal agencies should the regulatory function to some part be subject thereto. The regulating of the Department of Commerce not agency should also have the power to concerned with weather and climate resolve minor conflicts between agen­ research and development. cies, such as the precise timing of Earlier in this report there has been particular experiments. Any major discussed the nature of minimum reg­ disagreements would involve policy ulatory action which may be required and administrative coordination as on the part of the national Govern­ discussed below. ment to assure the integrity of ex­ periments conducted by Federal agen­ c. Inter-Agency Coordination of cies or their grantees and contractors. Policies and Program Activities It should be pointed out in this con­ nection that Federal agencies and The Commission recommends that their contractors and grantees them­ there be established within the Office selves will necessarily be subject to of Science and Technology (OST) a some of the same types of regulation special mechanism for the coordina­ that apply to commercial operations. tion of weather and climate modifica-

147 tion programs and for recommending the weather and climate modification such steps as may be appropriate for components. ICAS could continue to effecting a unity of governmental pol­ be concerned with atmospheric re­ icy in this field. search. If the general mission of developing the technology for climate modifica­ d. An Advisory Committee tion is assigned to a single agency, present overlap and lack of concerted The Commission also recommends effort among the various agencies will the utilization of the National Acad­ be remedied to a considerable extent. emy of Science and the National Due to the great importance of the Academy of Engineering for continu­ ing review and advice regarding the field, however, and because of the national program of weather and cli­ necessity of maintaining an interdis­ mate modification. ciplinary and international approach Both the President's Science Ad­ to weather activities, it is believed visory Committee and the Congress that continuing attention must be need to be able to obtain scientific and forthcoming from the Executive Office public policy advice from a group of of the President. Consequently, some knowledgeable people from outside mechanism concerned solely with the Government. This need could per­ weather and climate modification, haps be met by the appointment of a with emphasis on the development standing committee in the National and operational side, needs to be es­ Academy of Sciences in cooperation tablished within the OST. The OST's with the National Academy of Engi­ concern should embrace funding, basic neering. Such a committee includes research, applied research, develop­ persons with experience in the physi­ ment, testing and evaluation. Such a cal sciences, engineering, the biologi­ mechanism could take over from ICAS cal sciences and the social sciences.

148 Bibliography of reports remaining to (Editor), to be published in the Uni­ APPENDIX be published of research and studies versity of Chicago Department of performed under National Science Geography Research Papers in Febru­ Foundation grants and contracts in ary, 1966. support of the work of the Special Weather Modification: Law, Con­ Commission on Weather Modification. trols, Operations, H. J. Taubenfeld, Biological Aspects of Weather et al, to be published by the National Modification, Ad Hoc Weather Work­ ing Group, to be published in the Science Foundation in January, 1966 March, 1966 issue of the Bulletin of (NSF-66-7). the Ecological Society of America. International Relations and Human Dimensions of Weather Weather Modification, Leonard E. Modification, W. R. Derrick Sewell Schwartz, to be published by author.

149