Weather Modification and War

Science for the People is proud to republish this paper, originally presented by Science for the People member Peter Caplan at the Annual American Geophysical Union meeting in 1973, along with a new introduction from the author.

Weather Modification and War

By Peter Caplan

Peter Caplan is a retired research meteorologist specializing in cloud physics, and a member of the DC Metro Science for the People. 


I’m a retired meteorologist and longtime left and anti-war activist. My attempts to navigate the disconnect between a career that grew out of lifetime interest in things scientific on one hand—and growing political convictions on the other—entailed a struggle that’s familiar to many in SftP. This was especially so during the 1960s, with the Vietnam war and the cultural revolution heating up.

My research on the physics of clouds and precipitation led to an interest in weather modification as applied to the then ongoing attempts at taming hurricanes, suppressing hail, and increasing rainfall. It was easy to detect an odor of charlatanism and shoddy science surrounding these attempts, which were not proven statistically to be successful. Then when a violent or destructive weather event occasionally happened to follow a cloud seeding experiment, there were hasty attempts by scientists involved to walk back the inflated claims they had been making to justify their grants.

Professionally I taught on a college campus in upstate NY, then did research on numerical modeling with NOAA (my day jobs) while working politically, variously as a draft counselor, street theater organizer, agitator at AAAS annual meetings, and co-organizer of Science for the People groups in Syracuse, NY and later in Washington DC. I was an early subscriber to the SftP magazine, where I came across a 1972 piece written by the Chicago-based Science for Vietnam Collective about weather modification used over Indochina.

Here was the perfect opportunity to apply my training to some useful research. I presented this paper in 1973 at a joint meeting of the American Geophysical Union and the American Meteorological Society (hence the somewhat formal language)—and since it was unlikely to ever be published, I handed out mimeographed copies to all present, as well as to unsuspecting passersby in the hotel corridors. The paper emphasizes the cozy relationship between academia and the military and the application of technological solutions to social problems. Half a century ago there was already some concern in Congress and in the press about environmental side effects of geophysical warfare and both ambitious and alarming visions of extending its future use to geoengineering. So here we are, now with much more powerful scientific and technical capabilities—but in the hands of the very same forces.  We need science for the people—now more than ever!

Although the cost already borne by the people of Indochina in terms of human deaths and injuries is staggering, still more suffering awaits them as a consequence of the lingering effects of the new use of an old weapon — environmental warfare — on a scale never before seen. In a deliberate effort to control the insurgents by denying them the use of the countryside, the U.S. has system­atically attacked the ecosystem through intense application of herbicides, large-scale bulldozing, attempted creation of fire­storms, and the incredibly concentrated bombing (still going on in Cambodia), which has cratered vast areas and repeatedly damaged the dikes in North Vietnam. The effect in some areas has been termed “ecocide”, or irreversible damage to the environment.

In addition, the intentional generation of refugees by these methods has irreversibly altered the social structure, thus fitting the definition of environmental weapons given by Falk 1 as intended to “destroy the environment per se, or disrupt normal relationships between man and nature on a sustained basis.”

On a much grander scale, we have awaiting us a new class of environmental weapons having great power, but at the same time, sublety; these are to be the tools of what McDonald 2 refers to as “geophysical warfare”. These weapons, which include earthquakes, climate change, altered ocean currents, and tidal waves, can be triggered at a great distance from the victim and may be indistin­guishable from natural disasters. Although there is as yet no evi­dence that a capability to use these weapons exists now, one line of research that is being intensely pursued is climate modification. The most important work here is done under project “Nile Blue” (now called “Climate Dynamics” ) which, the Pentagon asserts is necessary because other major world powers have “the ability to create modification of climate that might be seriously detrimental to the security of this country” 3. Funding for computer time to run the necessary numerical simulations is over $3 million annually, and this year ILLIAC IV, the fastest machine available, will do the work.

A key precedent to the eventual use of geophysical warfare has already been established by the use, for the first time, of weather modification as a weapon of war. Having omitted the usual modifier “alleged” from the previous sentence, I will now review the evidence that this activity has actually occurred, then explore the attitudes and values, that have helped to bring it about.


The first disclosure of the hostile use of weather modifica­tion, in Jack Anderson’s syndicated column of March 16, 1971 4, stated that the Air Force had been stimulating rainfall over the Ho Chi Minh trail network since 1967. Shortly thereafter, Rep. Gilbert Gude and Sen. Alan Cranston began an unproductive 10-month correspondence on the subject with Administration officers 5. Senator Pell was less patient; when, after three months of government evasion, John Foster, director of defense research and engineering for the Pentagon finally informed him simply that the information he sought was classified, Pell published the whole correspondence 6. Two months later, Pell and 13 other senators submitted Senate Resolution 281, prohibiting both geophysical warfare and relevant research 7.

Finally, on April 18, 1972, Secretary of Defense Laird was questioned directly at Senate hearings 8 and replied “We have never engaged in that type of activity (weather control) over North Vietnam”. It wasn’t put to him at the time that it isn’t necessary to be “over” a country that small to have a significant impact on its rainfall.

At about the same time, an independent research group, Science for Vietnam, distributed a report 9 containing the first direct evidence on the subject—a reference in the Pentagon Papers to rainmaking over Laos in 1967. Deborah Shapley, in an extensively quoted article in Science 10 added another Pentagon Papers refer­ence and for the first time brought the facts before a large scien­tific audience.

At the Senate Foreign Relations Committee hearings 11 that preceded the U.N. Stockholm Conference on the Human Environment, it was made clear that key members of the U.S. delegation had not been adequately informed about S.R. 281. Russell Train, chairman of the delegation, had not received a copy and refused to express any opinion. As might have been expected the U.S. acted to dilute an already weak resolution requiring essentially that nations engaging in activities “in which there is an appreciable risk of effect on climate” should be open about these activities and consult with other nations. There was apparently some disagreement within the U.S. delegation, in the course of which it was revealed that it was the military that objected to the resolution 12.

Starting with the publication of an article by Bruce DeSilva, linking the summer 1971 flooding in North Vietnam to U.S. rain­making efforts, other accounts appeared in nationally-read news­papers 13. Seymour Hersh, on the basis of numerous interviews with high-ranking government officials and military sources, indi­cated that cloud seeding had been used as early as 1963, to control a Buddhist demonstration in Saigon, and later to increase the duration of the summer monsoon over North Vietnam, to hamper anti-­aircraft missiles, and to muddy infiltration routes. An official Pentagon spokesman responded to the articles only by insisting 14 that “we have not engaged in any (rainmaking) over North Vietnam”.

Hearings on Senate Resolution 281 took place on July 26 and 27 and, to a man, those in a position to have some knowledge about weather modification in Indochina refused to divulge it. These refusals imply not only that the press has been essentially correct, but that the program is of great significance. Another piece of evidence to support this view was commented on by Shapley 15: Weather modification was omitted from the final form of a.U.S.­-U.S.S.R. science and technology cooperative agreement after having been included in an earlier version.

In August, an excellent study by Gliedman 16 analyzed in painstaking detail the structure of dike systems of North Vietnam, explained how nearby bomb explosions can create invisible weaken­ing, and calculated possible rice crop losses from monsoon flood­ing. He estimated the relatively modest additional volume of water from rainfall at the end of the monsoon season (when waters are highest and soil saturated) that would be needed to cause flooding; then compared that to the volume claimed to be obtainable by the latest weather modification techniques. He concluded that existing techniques could have produced dangerous flooding. The most recent item in this collection dates back to last September 8 when a Canadian corporation sued the Pentagon to receive compensa­tion for alleged use of its cloud-seeding device over SE Asia 17. Congressional reaction to these disclosures has been mild, con­sisting only of a few pieces of legislation opposing environmental warfare.


The public reactions by meteorologists have ranged from shoulder-shrugging to anger, but none expressed much surprise; meteorology and the military have long been bedfellows. Their symbiotic relationship was recently celebrated by Best18, but it dates back at least to the initial establishment of a National Weather Service in 1870 under the Army Signal Corps. Now, one hundred years later, the combined DoD-NASA portion of Federal meteorological research expenditures exceeds 60%, and the military is still the leading employer of meteorologists.

Although civilian agents now conduct most of the weather modification research, its origins are military. The initial field experiments in cloud seeding, the laboratory experiments that preceded them, and the early years (1946-1950) of development were mostly financed by the military 19. Periodic reports by many government-appointed groups on the status of weather modification have exhibited a curious schizophrenia with respect to the military. They list all of the military research being conducted, dutifully express the need for international cooperation and peaceful uses of weather modification, yet fail to recognize how one can affect the other, or to acknowledge that the military research being de­scribed has very real offensive as well as defensive potential. The NSF Special Commission report of 1966 20, for example, innocently recognized a “remote possibility that sometime in the future a nation might develop the capability to use weather modification to inflict damage on the economy and civil population of another country”, while the NAS 1971 report 21 allowed that “military applications of weather modification are conceivable” (emphases added). St. Amand, back in 1966 22 was more forthright: “We regard the weather as a weapon. Anything one can use to get his way is a weapon and the weather is as good a one as any”. His reaction to the recent disclosures was 23 “I don’t think using weather to discourage people from moving is a bad thing to do”.

In the hearing on S.R. 281, when Senator Pell asked DoD spokes­man Benjamin Forman about military uses of weather modification, Forman mentions protection of “our personnel and resources against weather hazards”. When asked how rainmaking can do this, all he could come up with is that it might help relieve a drought at some overseas base! DoD later added that, among other non-offensive applications, it wished “to build a technology base for the capa­bility to verify the use of weather modification by an enemy” 24. Ferdinand de Percin of the Army Research Office writing in the Army R&D News Magazine 25 was only slightly more forthright; he mentions the use of warm fog dispersal techniques to deny natural concealment to the enemy. Obviously, the Pentagon is being discreet about its rainmaking plans.


Since a sizeable portion of militarily supported research is done by people outside the military, some of whom hold academic positions, it is enlightening to look at the Pentagon’s views of the benefits of collaboration between itself and the campus. William J. Price. executive director of the Air Force Office of Scientific Research pointed out 26 that “One of the strengths of the DoD-university relationship is that it is built upon mutual understanding and respect for their common interests”. Universities must function in such a way as to “assure the future of society” (U.S. society, presumably). Professors are depicted as desiring “especially to work on problems of national security… in their concern to assure the future of society” (surely not anything so prosaic as scrounging up research money from whatever source is available!). Price estimates that DoD in 1968 supported up to half of Federal research in math, physics, and engineering on campus.

Compliance with the Mansfield amendment to the 1970 Military procurement Authorization Act has caused some problems. It required, as originally worded, that DoD-sponsored research bear “a direct and apparent relationship to a specific military function or opera­tion”. According to Shapley’s account 27 of DoD research at Stanford, the Defense Documentation Center has for its records changed the titles and, in some cases, the descriptions of proposals approved by DoD to justify funding them.

Just what is required of the DoD-sponsored scientist was made clear by Paul Lukasik, director of their Advanced Research Projects Agency (ARPA): He must have a “degree of objectivity that enables him to separate his science from his advice. He can work in the area of quantum mechanics regardless of his position on ABM… or on (the) test ban treaty” 28. In other words, as long as he lets the DoD pick his mind, what his conscience says is irrelevant. Lukasik continues “…the universities… not only provide input to us, but they learn from us…”. Thus General Best is not the only one to talk about symbiosis.

This view of the university scientist as an objective intellect to be placed at the disposal of the government can equally well be applied to scientists outside the university. It is stated succin­ctly in Reed’s explanation 29 of the philosophy that went into the AMS statement on S.R. 281: Simply stated, it is the government (not, in this case, the AMS) that is to determine “the use to which meteorological knowledge and skill are ultimately put”. The message that AMS and DoD seem anxious to communicate is that scientists, when they act in this matter are being politically neutral. Far from it—just doing science is taking a stand. Scientists and their work are used—and mainly by the most powerful institutions in our society—the corporations and the military; these control the government, and the government controls the schools. The main concern of those in power is to maintain that position—at the expense, if necessary of a goodly part of the rest of humanity. Where the only scientific opinion heard by the public comes from scientists on the payrolls of the powerful, it is imper­ative that other voices be heard. Having the privilege of far more education than most of the public, the scientist has a unique responsibility to challenge and criticize; if he shirks it, his silence is interpreted not as neutrality, but as acquiescence.


So far I have sought to establish (a) that geophysical warfare is on the way; (b) that hostile weather modification is an important step in that direction; (c) that weather modification of this kind has actually occurred; (d) that those connected with this field have long suspected that this would occur; (e) that refusing to take responsibility for the uses to which research is put is not neu­trality, but support for the users. Now that weather modification has been turned to destructive ends and, since it is likely that certain elements will try to apply any future experimentation in this field to destructive ends, let me take this opportunity to raise the question “is it worth it?”

The history of weather modification has been marked by extra­vagant claims for its potential benefits. For instance, Langmuir in 1947 30, in describing his pioneering work, speculated that seeding could eliminate aircraft icing due to stratus, increase greatly orographic rainfall, weaken thunderstorms, and even decrease the winter cloudiness over the northern U.S. Commercial rainmaking activities prospered in the following years, reaching a peak in 1952 with about 300 million acres, or 10% of the entire country seeded 31. Seeding was also occurring in 30 nations abroad. After a period of retrenchment, there was steady growth in U.S. funding of weather modification, the total rising from $2.4 million in 1960, to $12.0 million in 1970, to $25.1 million in 1972 32. While fairly restrained statements were made during most of the 50’s, after Sputnik, there were dark hints about Russian progress, typified by Houghton’s statement 33 “I shudder to think of the consequences of a prior Russian discovery of a feasible method of weather control”, prompting a Russian writer to characterize him as having a twisted mind. Comments about Russian progress and its implications have tended to be less overt since then.

The 60’s saw a return to drum-beating on behalf of weather modification, with the AMS in 1962 34 holding out hope of “tre­mendous economic and humanitarian advantages” and, in 1967 35 “great benefit to mankind”. No less a personage than Lyndon Johnson proclaimed in 1963 36 that we will some day “eliminate droughts and floods, bring rain to the deserts, and control deluges of jungles”; and in 1967 37 Robert M. White held out hope of improv­ing “the well-being of people in ways and to a degree that are now inconceivable”.

Nearly all of the numerous summaries on weather modification produced in the past dozen years have, in addition to rosy pre­dictions and sober peace appeals, carefully enumerated unsolved problems of a political, social, legal, economic, and ecological nature, and gone on to request enormous increases in funding. The Newell report 38, for instance, recommended growth of from $10 million in 1967 to $90 million by 1970! There is little doubt that these years have brought a substantial improvement in our under­standing of nucleation and precipitation processes and in weather modification techniques; but little has been done about the problems that accompany weather modification. Take, for example, just one problem—the question of who is to benefit when choices must be made. To the extent that weather modification works, it is certain that competing demands for its application will render difficult any attempts to confine its use to small scale (in time and/or space). But, attempts at large-scale repeated modification would lead to changes in climate, which would alter the ecology, which in turn could cause dangerous increases in diseases and pests, such as those warned about in the NSF Commission report 39 and Commoner 40. Harmful accumulations of silver iodide, as mentioned in Cooper and Jolly 41 are another possibility. If modification were to be restricted to small-scale operations because of these side effects, then who would be chosen to benefit? If the history of cold fog modification is any indication, it will be the wealthy and influential whose interests will be served: Given an annual toll of 1000 traffic deaths and $400 million in damages due to fog 42, it is noteworthy that almost no attention has been paid to the application of fog clearance techniques to highways. Apparently, the lives of people who fly (such as the meteorologists, and the congressmen who dole out the appropriations) are worth more than the lives of those who drive.

In the case of droughts, for example, with only small-scale rainmaking allowed, it is therefore bound to be not the small farmer who benefits, but rather “agribusiness”. The former, in fact, could very well be left to suffer from downwind rainshadow effects. Similar distribution of efforts can be expected for hail suppression. Thus, it appears that, with a few exceptions, the only practical uses for weather modification are going to be military uses. (Possible exceptions could include a freak drought over a small island; a radiation fog on a busy highway; or, frequent destructive hailstorms over a small intensely farmed region (such as the Po valley43).


The practice of applying technological solutions to social problems has become a serious disease of Western society. By way of example: Drugs for unruly schoolchildren; electric shocks and lobotomies for uncooperative prisoners; birth control campaigns instead of more equitable distribution of resources in poor coun­tries; antipollution devices instead of free public transportation; heart transplants instead of adequate basic health care; methadone for heroin addicts; chemical fertilizers; poisonous pesticides; — in fact, the Indochina war itself, where, when political methods failed and ordinary violence failed, our resort was technology — infrared sensors, air-dropped antipersonnel weapons, the computerized electronic battlefield and, of course, weather modification.

In most cases, the technological solution is merely a short­-range palliative that, at best, puts off the day when the under­lying social problem will have to be dealt with and, at worst, exacerbates it. Where the social problem arises from lack of cooperation and organization, the technical solution only succeeds in increasing the isolation of people from one another and from nature, fostering a false sense of self-sufficiency and increasing destructive competition.

Weather modification, even in its relatively beneficial peace­time uses, suffers from many of the drawbacks inherent in techno­logical solutions. If we organize ourselves rationally, we needn’t always attack nature in order to survive comfortably. Protecting people against tornadoes and hurricanes, for instance, need not call for making war on the elements; rather it calls for setting up some kind of organization, using the tools we now have, to warn people in time, evacuate them, and provide full compensa­tion for property damage. Recent advances in weather modification techniques, have led to a sharp increase in funding. This may be the beginning of a stampede that will not in the long run benefit the people.

The considerations brought forth in this paper indicate that the wisest course of action at this time may be a moratorium on all forms of weather modification until such a time as the questions raised here are adequately dealt with.


  1. Falk “Prohibiting Military Weather Modification” (PMWM), hearings before Subcomm. on Oceans and International Environ­ment, Sen. Comm. on Foreign Relations, 1972, testimony of Richard A. Falk, p. 38.
  2. ibid., p. 124, from G. J. F. MacDonald, “How to Wreck the Environment” in Unless Peace Comes, Nigel Calder, ed., Viking, N.Y.C., 1968.
  3. DoD Appropriations for FY 1972. Hearing before Sen. Comm. on Approp., 1971, p. 739.
  4. Anderson, Jack, “U.S. Rainmakers proving success over Ho Chi Minh trails”, Bell-McClure Syndicate, March 16, 1971
  5. PMWM, pp. 103-108.
  6. Cong. Record, Jan. 26, 1971, S 508
  7. ibid., March 17, 1972
  8. Foreign Assistance Act, Hearings before Sen. Comm. on Foreign Relations, April 18, 1972, pp. 128, 159
  9. Science for Vietnam, Chicago Collective, “The big gun is the rain”, (Publ. at 1103 E 57 St., Chicago, 60637)
  10. Shapley, “Rainmaking: Rumored use over Laos alarms experts, scientists.” Science 176, pp. 1216-1220.
  11. “U.N. Conference on Human Environment: Preparations and prospects”, Hearings before Senate Comm. on Foreign Relations, May 3, 1972, p. 20.
  12. Shapley, D. , “Rainmaking: Stockholm Stand watered down for Military”. Science, 176, p. 1404.
  13. DeSilva, Providence (R.I.) Journal, June 20, 1971; Cohn, Victor Washington Post, July 2, 1972; Wilford, John N., N.Y. Times, July 3, 1972; Hersh, Seymour, N.Y. Times, July 3, 1972 and July 9, 1972 (all of these also in PMWM, pp. 5-17); in addi­tion: Cowen, Robert C., Christian Science Monitor, July 3, 1972.
  14. Hersh, Seymour, “ ‘67 order to end rainmaking reported”. N.Y. Times, July 4, 1972 (quote is from Jerry Friedheim)
  15. Shapley, D., “Science officials bow to military on weather modification”. Science, 174, p. 411, 1972.
  16. Gliedman, John, Terror from the Sky, Vietnam Resource Center, Cambridge, Mass., 02139, 1972.
  17. Shapley, D., “Weather Watch”. Science, 178, pp. 144-145, 1972
  18. Best, W.H., Bull. Amer. Meteor. Soc., 53, 5, 429-432, 1972
  19. Schaefer, V.J., ibid, 49, 4, 337-342, 1968
  20. “Weather and Climate Modification”, report of NSF Special Commission on Weather Modification. NSF 66-3, 1966, p. 119
  21. “The Atmospheric Sciences and Man’s Needs”, report of Comm. on Atmos. Sciences, National Res. Council, NAS, Washington, D.C., 1971, p. 56.
  22. “Weather Modification”, testimony of P. St. Amand before Senate Comm. on Commerce on S23 and S 2916, 1966.
  23. Shapley, D., see (10)
  24. PMWM, testimony of Benjamin Forman, p. 36
  25. dePercin, F.P., Army R & D News Mag., Sept. 1972, 24-27
  26. Price, W.J., A.F. Res. Rev., July-Aug. 1970, 6-9
  27. Shapley, D., “Defense Research: The names are changed to protect the innocent”. Science, 175, 84 1972, 866-868
  28. Dept. of Defense Appropriations for FY 1973, Hearings before Senate Comm. on Appropriations, testimony of P. Lukasik, March 14, 1972, p. 75.
  29. Reed, R., Bull. Amer. Meteor. Soc. 53, 12, 1185-1191, 1972
  30. Langmuir, I., in “Final Report, Project Cirrus”. G.E. Res. Lab., Schenectady,1948, p.18
  31. Huschke, R., Bull. Amer. Meteor. Soc. 44, 7, 1963, 425-429
  32. Droessler, E., ibid., 53., 4, 1972, 345-348
  33. Houghton, H., ibid., 38, 10, 1957, 567-570
  34. Amer. Meteor. Soc., ibid., 43, 8, 1962, 400-401
  35. Amer. Meteor. Soc., ibid., 49, 3, 1968, 272-273
  36. “Government Weather Programs”, House Report #177, 1965, p. 151 (Statement made May 2, 1963)
  37. White, Robert M., quoted in “Weather and the hand of man”, ESSA pamphlet, 1967, p. 2
  38. Newell, Homer, “Recommended national program in weather modification”, report to ICAS, 1966, p. VI-3
  39. “Weather and climate modification” — see ( 20), 68-69
  40. Commoner, Barry, The Closing Circle, Bantam, 1972, p. 245
  41. Cooper, C.F., and W.C. Jolly, Water Resources Res. 6, 1, 1970, 88-98
  42. “Study Finds division on proper method of driving in fog”, N.Y. Times March 10, 1973, p. 21
  43. Morgan, Griffith, J. Appl. Meteor., 12, 2, 1973, 338-353