Investigating The Climate Impacts Of Nuclear War

Investigating the Climate Impacts of Nuclear War Illustration from a 1985 report by Lawrence Livermore National Laboratory scientist Michael MacCracken, showing smoke and soot lofted from nuclear detonations on day 1 and the passage of the smoke 5, 10, and 20 days later (See Document 13, “Global Atmospheric Effects of Nuclear War”) Illustration from a 1985 report by Lawrence Livermore National Laboratory scientist Michael MacCracken, showing smoke and soot lofted from nuclear detonations on day 1 and the passage of the smoke 5, 10, and 20 days later (See Document 13, “Global Atmospheric Effects of Nuclear War”) 1983 Lawrence Livermore Study Said Nuclear Exchange Could “Dramatically Affect the Atmosphere’s Temperature” Defense Nuclear Agency Saw Nuclear War Producing “Atmospheric Trauma” 1988 Interagency Study Projected “Severe Disruption of [Food] Production, Processing, and Distribution” President Reagan Stated That Nuclear Winter Was “Theoretically Possible” Published: Oct 30, 2024 Briefing Book # 872 Edited by William Burr For more information, contact: 202-994-7000 or nsarchiv@gwu.edu Subjects Energy and the Environment Nuclear Strategy and Weapons Science and Technology Project Climate Change Transparency Project Nuclear Vault Potential Global Effects "Potential Global Effects". Chart from Defense Nuclear Agency February 1984 briefing on “Global Effects of Nuclear War,” indicating “atmospheric trauma” caused by cooling from fires and smoke in the troposphere (See document 4) Richard Turco, Brian Toon, and Thomas Ackerman Richard Turco, Brian Toon, and Thomas Ackerman, three of the authors of the December 1983 article in Science, “Nuclear Winter: Global Consequences of Multiple Nuclear Explosions,” which had a critical impact on U.S. government investigations of the possible climactic impact of nuclear war. Turco, Toon, and Ackerman are shown in December 2019 with later collaborators Alan Robock and Gera Stenchikov, at a meeting of the American Geophysical Union. (Photo courtesy of Alan Robock) Carl Sagan Carl Sagan (1934-1996), the most famous of the group of scientists who co-wrote the 1983 article in Science, was a planetary scientist at Cornell University. He narrated and co-wrote the hugely popular, award-wining PBS television series Cosmos: A Personal Voyage (1980). James Pollack James B. Pollack (1938-1994), an astrophysicist at NASA’s Ames Research Center, was co-author of the TTAPS (Turco-Toon-Ackerman-Pollack-Sagan) 1983 Science article on nuclear winter. Michael MacCracken Michael MacCracken, a scientist at the Department of Energy’s Lawrence Livermore Laboratory, did pioneering work on the possible impact of nuclear warfare on the climate. (Photo from the Climate Institute’s Web site) UPDATE See the original June 2, 2022, posting below this update Washington, D.C., October 30, 2024 - A 1983 study from scientists at the Department of Energy’s Lawrence Livermore Laboratory said that a full-scale nuclear war between the superpowers would “dramatically affect the atmosphere’s temperature, dynamic, precipitation, and chemistry,” reduce “the light reaching the surface in the Northern Hemisphere by 90% or more,” and could cause “a cooling of continental land areas by up to 30°C.” The recently released internal study of the “Global-Scale Physical Effects of a Nuclear Exchange” is featured in an update to the National Security Archive’s 2022 Electronic Briefing Book on U.S. government thinking about the possibility of a “nuclear winter,” in which the fire effects of multiple nuclear detonations would produce enough smoke and soot to block sunlight and dramatically lower the Earth’s temperature. * * * * * 1983 was a year of increasing tensions between the Cold War superpowers, highlighted by the Soviet shootdown of a South Korean airliner (KAL 007) in September, a Soviet false alarm, and war scares on the Soviet side. It also saw massive protests against NATO missile deployments, and the nuclear freeze movement continued to gain momentum in the United States. At the same time, the scientific community was beginning to focus more intently on the risks of nuclear war. At the close of 1983, a group of scientists published a ground-breaking article in Science magazine asserting that the mass fires caused by nuclear war could inject enough smoke and soot into the atmosphere to obstruct sunlight and dramatically lower temperatures to freezing levels—nuclear winter. A longer version of the report published in Science had been circulating privately for some months when scientists at Lawrence Livermore National Laboratory (LLNL), one of the two Department of Energy nuclear weapons labs, did its own internal study of the impact of nuclear war on the global climate. LLNL’s August 1983 report focused on the potential cooling effects of a nuclear war, finding that a superpower conflict involving the detonation of more than 6000 nuclear weapons could produce mass fires, both in urban areas and in forests. The fires would introduce a large amount of smoke and soot into the atmosphere, a phenomenon that could “reduce the light reaching the surface in the Northern Hemisphere by 90% or more” and that could “lead to a cooling of continental land areas by up to 30°C.” The “reference scenario” used for the study posited a war where the total explosive yield of 5300 megatons was spread by some 6300 nuclear warheads. One third of the megatonnage was caused by U.S. warheads and two thirds by Soviet. About 2500 of the megatons were surface bursts with 85 percent of them from Soviet weapons. The authors did not explain why they assumed that the Soviets would detonate most of the surface bursts; it may have been an arbitrary assumption. Another scenario that was considered involved a “significant European theater component” with a total yield of 6500 megatons spread by 10,000 warheads, many of which were “tactical air burst[s].” The European scenario was not discussed further. To analyze the climate impact of the reference scenario, the authors produced a complex and demanding report covering a wide variety of issues relating to the impact of thousands of nuclear detonations. They included the spread of radioactive debris (fission products), the impact of ultraviolet radiation on the ozone layers, the radiative effects of dust and nitrogen oxides, the fire effects of the nuclear detonations, and the effects of soot emissions on the troposphere. At the heart of the presentation is a section on “Global Climate,” where the authors suggested that the “burning of 13000 Tg [teragrams] of fuel in cities, urban areas, and forests” in the mass fires caused by thousands of nuclear detonations “can dramatically affect the atmosphere’s temperature, dynamic, precipitation, and chemistry.” (A teragram is a unit of mass in the metric system. 13000 teragrams is the equivalent of 13,000,000,000,000,000 grams or over 28 trillion pounds.) According to the authors, the perturbations caused by the injection of so much soot and smoke into the atmosphere could “lead to modifications of the weather and climate” that could produce “reductions in average Northern Hemisphere land temperatures of 5-10° centigrade and perhaps several times more over mid-continental regions.” The cooling effects could take place within five to 10 days, and the “cooling of mid-continental regions could be substantially larger.” They also projected a decrease in the “precipitation rate of 20-30% over the cooled land region and by 5-10% over ocean region, where atmospheric warming has stabilized the upper troposphere.” The authors believed that their line of approach involved many uncertainties and unverified assumptions and they pointed them out. For example, the degree of cooling would depend on the elevation of the smoke and the “effect of cloud cover changes.” Moreover, “unknown parameters” included the scale of the “mass loading [of soot and smoke] from fires” and how long particulates would reside in the atmosphere. In addition, the process that filters soot, smoke, and dust from the atmosphere and the mechanisms that transport them “are assumed to be those of an unperturbed atmosphere.” That assumption “was clearly not valid,” according to the study, but there were no “computational tools” at hand to overcome that problem. In addition, the “coupling” of the various climate effects of nuclear war or their “synergistic interactions” required serious analysis. The authors noted that what stimulated their study and several related ones was a 1982 article by Paul J. Crutzen and John W. Birks titled, “The Atmosphere after a Nuclear War: Twilight at Noon,” that analyzed the impact of the soot produced by nuclear fire effects. The Crutzen-Birks article also inspired a report prepared by Richard P. Turco, Owen Brian Toon, Thomas P. Ackerman, the late James B. Pollack, and the late Carl Sagan (collectively known as TTAPS), who were circulating their March 1983 report, the main findings of which were published later in the year in Science. The National Academy of Sciences also had a study in the works. Although the Livermore report discussed “cooling” rather than freezing or subfreezing and emphasized the uncertainties, its authors found that their research results were in “qualitative accord” with the findings of TTAPS and the ongoing National Academy investigations.[A] Edward Teller, the founder of LLNL and then its director emeritus, was a major influence in the nuclear weapons field and in the early 1980s was focused on the promotion of the Strategic Defense Initiative. The possibility that nuclear war could have a significant climate impact had never occurred to Teller, who was surprised by the TTAPS findings and wanted to find ways to refute or weaken them. Teller would criticize the nuclear winter concept in an article published in the journal Nature for which he received assistance from LLNL staffers.[B] Yet, Teller, like the LLNL staffers could “not simply discard [the] theory.” As he wrote, the “possibility of nuclear winter has not been excluded.”[C] Michael MacCracken, one of the authors of the 1983 LLNL study and a Teller Ph. D student, would move forward with studies of the cooling impact of nuclear war and the uncertainties of the nuclear winter thesis, although the latter remains highly influential. In the original release, citing privacy grounds, the Department of Energy withheld the names of the project leaders and participants in this report. The National Security Archive challenged the excisions because so much time had passed since the publication of this report, and DOE duly released the names. The project team leader included MacCracken along with Joyce Penner, Robert Perrett, Bruce Tarter, Frederick Luther, and Joseph Knox. The Document New document Lawrence Livermore Laboratory, “LLN Study of the Global-Scale Physical Effects of a Nuclear Exchange: Preliminary Findings,” 15 August 1983, unclassified Aug 15, 1983 Source: FOIA release by Department of Energy ** Original “Nuclear Winter” Posting ** Nuclear Winter: U.S. Government Thinking During the 1980s Washington, D.C., June 2, 2022 – The apocalyptic threats emanating from Moscow over the Ukraine war raise the terrible prospect of nuclear weapons use. The probabilities may be low, but if a major nuclear war occurred, the catastrophic impact of a so-called nuclear winter could be felt on a global scale. Today the nongovernmental National Security Archive presents an assortment of government and contractor reports from the 1980s, when scientists first surfaced the nuclear winter theory. These records describe preliminary efforts to explore the thesis along with related issues. Although the topic quickly became politically charged, some high-level officials including President Ronald Reagan indicated that they accepted the concept was theoretically possible. Among the primary documents posted today are an early overview of the Defense Nuclear Agency’s research program, published for the first time, concluding that a large-scale nuclear exchange could cause “atmospheric trauma” with “serious potential for severe consequences” for the weather and climate. Also in the compilation are progress reports on the Lawrence Livermore National Lab’s research agenda, and a CIA report from late 1984 on nuclear winter research in the former Soviet Union. Nuclear Winter: U.S. Government Thinking During the 1980s By William Burr The apocalyptic threats emanating from Moscow over the Ukraine war raise the terrible prospect of nuclear weapons use. The probabilities may be low, but if a major nuclear war occurred, the catastrophic impact would be felt on a global scale. For example, climate experts have raised the dire possibility that a nuclear war, whether centered in Europe or between Russia and the United States, could produce a “nuclear winter” across the planet with soot from burning cities lofted into the stratosphere blocking sunlight and severely lowering temperatures.[1] The theory of nuclear winter (NW) emerged in the early 1980s during a period of renewed Cold War tensions. An article published in a December1983 Science magazine article that made an original argument about the possibility of “nuclear winter” produced great controversy and became the subject of scrutiny by scientists and U.S. government agencies. Among others, the Defense Nuclear Agency (DNA) began sponsoring studies and an internal DNA briefing raised the possibility that a large-scale nuclear exchange could cause “atmospheric trauma” with “serious potential for severe consequences” for the weather and climate. The writers of the article in Science were scientists Richard P. Turco, Owen Brian Toon, Thomas P. Ackerman, the late James B. Pollack, and the late Carl Sagan, collectively known as TTAPS.[2] Sagan, then with Cornell University, was the best known of a group that had concentrated years of work in physics, chemistry, astrophysics, and meteorology into their article. Turco was the only one who had done some work on nuclear weapons effects, but studies by the others of Martian dust and the impact of asteroids and volcanic eruptions contributed to the theory. Sagan’s talents as a science popularizer, demonstrated by the highly popular PBS show Cosmos, were important and gave allure to the serious arguments made by the TTAPS group. Influencing the work was another collaboration: an article, published in the June 1982 issue of Ambio by Paul J. Crutzen and John W. Birks, called “The Atmosphere after a Nuclear War: Twilight at Noon,” which focused on the soot produced by nuclear fire effects. [3] The topic of nuclear winter immediately became politically charged, especially in light of Cold War tensions and ongoing calls for a “nuclear freeze.” Two of the TTAPS authors, Pollack and Toon, worked for NASA and faced some institutional pressures not to present.[4] Nevertheless, they found fora where they could introduce their theory of the climatic impact of nuclear war. Realizing that nuclear explosions were not just about blast or radiation effects but also fire, TTAPS argued that the smoky soot generated by nuclear attacks on urban centers could have a “major impact on climate manifested by significant surface darkening over many weeks, subfreezing land temperatures persisting for up to several months, large perturbations in global circulation patterns, and dramatic changes in local weather and precipitation rates.” The impact on agriculture and food supplies could be drastic. It was Richard Turco who coined the phrase “nuclear winter” to characterize the phenomenon. That a group of outside experts had developed an original theory about the connection between firestorms and smoke and the climate surprised Pentagon nuclear experts who had never considered the possibility. As Defense Secretary Caspar Weinberger’s adviser on nuclear weapons put it, “not only the Department of Defense but … the scientific community in general ought to be a bit chagrined at not realizing that smoke could produce those effects as long as they do, not question about it.”[5] Acknowledging uncertainties about their findings, the TTAPS authors declared that the “magnitude of the first-order effects are so large, and the implications [are] so serious,” that further scientific research was essential. There were important issues to investigate, such as: how much smoke would a nuclear conflict produce, how high would it loft, how long would it remain, and how long would any climate effects persist? [6] Scientist at universities, think-tanks, and government agencies began to scrutinize the theory closely and initiated research programs to evaluate the possibility of a nuclear winter. With Pentagon support, the National Academy of Sciences’ National Research Council produced one of the major early reports while the Scientific Committee on Problems of the Environment (SCOPE) published a huge study on the environmental impact of nuclear war. Also investigating nuclear winter were the Defense Nuclear Agency (now Defense Threat Reduction Agency) and DOE’s Lawrence Livermore National Laboratory (LLNL). Some in the Reagan administration saw NW theory as a political attempt to press an arms control agenda. Although Pentagon nuclear experts expressed consternation that they had never considered the connection between firestorms and smoke and the climate, the Defense Department’s official statement stressed the technical uncertainties and the validity of current nuclear policy [see Document 12]. Some arms controllers also emphasized the uncertainties; MIT’s George Rathjens was deeply critical of TTAPS’s methodology and conclusions, arguing that the authors had published prematurely.[7] Interestingly, President Reagan saw something in the theory. During a February 1985 press conference he made a statement suggesting acceptance: Mentioning the 1816 Tambora volcanic eruption which cooled the earth and produced famines, Reagan asked “if one volcano can do that, what are we talking about with the whole nuclear exchange, the nuclear winter that scientists have been talking about?”[8] Today’s posting presents a group of government and contractor reports from the 1980s that describe the ongoing efforts to explore the nuclear winter thesis and related issues. The point of this posting is not to settle the validity of the theory, whose only true laboratory test—the measurement of a full-blown nuclear war—is unthinkable. Nevertheless, the early U.S. government efforts to explore the theory and its implications are worth noting, in part for the light they shed on nuclear winter theory, although some of them were written more for political effect than to raise serious questions about the science. Some of the reports are quite demanding and will be of particular interest to readers with background in the sciences. While important scientific work on nuclear winter theory has been published over the years in academic publications, it cannot be included here because of copyright issues and sheer quantity. Among the primary documents, an early overview of DNA’s research program is published for the first time. So are progress reports on LLNL’s research agenda. The studies that eventuated from the DNA and LLNL research are not yet available, but a sense of the ongoing work at Livermore emerges in a study by Michael MacCracken who estimated that nuclear soot lofting to the troposphere could cause “relatively large decreases in temperature” if not a “deep freeze.” Also included are reports from the RAND Corporation and the Defense Department about the implications of nuclear winter for military policy. Also included is a CIA report from late 1984 on nuclear winter research in the former Soviet Union. Soviet findings on the topic paralleled the results of the TTAPS authors, but the CIA assessed the research done in the Soviet Union as derivative and unlikely to have an impact on high-level policy, although it did have an impact on propaganda efforts. In 1986, the General Accounting Office (GAO) published a report on nuclear winter that received little notice at the time but deserves to be remembered. That the GAO was even-handed in its assessment of nuclear winter – as a “plausible” theory – irritated the White House Office of Science and Technology which also disliked the GAO’s candid discussion of the vicissitudes of federal funding for research. While an interagency committee had considered $50 million in spending on NW research for five years, the agencies whittled it down to a few million in new spending with no future commitments. Thus, limited federal funding constrained research on nuclear winter. Finally, today’s posting includes another little-noticed report; a 1988 study published by the Committee on Interagency Radiation Research and Policy. This U.S. government committee sponsored a review of volume 2 of The Environmental Consequences of Nuclear War, published in late 1985 by the Scientific Committee for Problems of the Environment (SCOPE), which addressed the ruinous impact of nuclear war on agriculture and the ecology. The report by the interagency committee found that, if anything, the SCOPE report understated the devastation to agriculture and food supplies that would be caused by the atmospheric effects of a nuclear war. The winding down of the Cold War in the late 1980s and early 1990s reduced the urgency behind research on nuclear winter, but did not end it. The TTAPS authors produced an update in 1990, also published in Science, which found that the “basic physics of nuclear winter” had been affirmed, while noting various remaining uncertainties, such as over fire-ignition and the generation of smoke. They also observed that the latest research had strengthened their findings. Other scientists, for example, Livermore’s Steven J. Ghan, produced a 1989 report on “Chronic Climatic Effects of Nuclear War,” published in a 1991 issue of Atmospheric Environment, which found potential for “grave climatic consequences.” Some of researchers worked closely with members of the TTAPS group, such as Rutgers University meteorologist Alan Robock; they persisted in the work on nuclear winter but also became closely involved in research on climate change. Robock would work with Toon, Turco, and others in producing studies elucidating the theory and the possibility that regional nuclear conflicts could have severe environmental effects.[9] Ongoing requesting by the National Security Archive for classified and unclassified U.S. government reports, such as documents emanating from LLNL’s research efforts, may elucidate the U.S. government’s internal review of nuclear winter theory. Whether any U.S. government agencies have studied the climatic risks of nuclear war since the 1990s remains to be learned, but in the FY 2021 defense bill Congress included a requirement for the National Nuclear Security Administrator, in consultation with the Secretary of Defense and the Director of National Intelligence, to request a study by the National Academy of Sciences of the atmospheric effects of nuclear explosions, including the impact of soot and other debris from fires. Although the NNSA has yet to issue a contract to the NAS for the study, the possibility of nuclear winter is back on the U.S. government’s research agenda. Note: Thanks to Frank von Hippell, Princeton University Program on Science and Global Security, for helpful comments on this posting. The Documents Doc-1 Document 1 Harold Brode et al., Fire, Airblast, and Underground Effects from Nuclear Explosions - Some Current Progress, 1 January 1981, Pacific-Sierra Research Corporation, Classification Level Unknown Jan 1, 1981 Source FOIA release The work of physicist Harold Brode at the Pacific Sierra Corporation influenced nuclear winter research, Members of the TTAPS group had worked with Brode and the group cited his work in the original December 1983 Science article hypothesizing about the phenomenon. Brode was less interested in the global impact of fire effects than in the problem of developing predictive models that could fully account for the local impact of nuclear weapons effects. He and others at PSC saw such techniques as essential because of “the enormous carnage and confusion accompanying a nuclear attack, and the unprecedented potential for casualties and damage from the subsequent fires.” Looking back at the destruction of Hiroshima and Nagasaki would support that perspective, he argued, because “the damage due to fire was much greater and more complete than that due to blast from the nuclear bombs or from equal tonnages of high-explosive bombs.” Brode and his colleagues further explained that the “vast amounts of gas, smoke, hot air, and ashes generated by the fire may cause high casualties” and “the very size of the burning region precludes escape for most of those caught within the area.” The existence of high yield thermonuclear weapons made predictive techniques all the more important since the point was “not only that much damage is not counted, but also that much larger attacks than necessary may be planned.” This study is difficult for the mathematically-challenged (such as the present writer), but the text clearly conveys the importance of Brode’s effort. In this study Brode and his colleagues sought to “delineate the damage expected from a superfire, and … [to] aid both those planning or assessing nuclear weapon attacks and those planning defense against such attacks.” They supported the development of computer programs that could make it possible to make “general predictions of the extent of fires in unspecified urban areas,” predictions that would be “as reliable as those for blast damage.” By the late 1980s Brode had developed predictive models for nuclear fire-storms that could be incorporated into target planning and provide for more reliable understanding of the destructiveness of nuclear weapons. While discussion with officials at the Pentagon and Omaha would go far, in the end military officials chose not to adopt Brode’s models, partly for budgetary reasons, but mainly because they were not necessary to achieve the requisite levels of damage – which was after all their assigned objective– without considering fire effects or having to think deeply about how much devastation the weapons could actually cause.[10] Doc-2 Document 2 Michael MacCracken, [Deputy Division Leader] Atmospheric and Geophysical Sciences Division, Lawrence Livermore National, “Nuclear War: Preliminary Estimate of the Climactic Effects of a Nuclear Exchange,” Paper presented at the Third International Conference on Nuclear War, Erice, Sicily, August 19-23, 1983, UCRL- 89770, October 1983 Oct 1, 1983 Source OSTI Web site Michael MacCracken, a physicist and climate expert at Lawrence Livermore Laboratory, played a central role in the lab’s research on nuclear winter. In this conference paper, representing his initial take on the recent research by TTAPS and other analysts, MacCracken wrote that the climatic effect of nuclear war that was of “most concern … is the very large, nearly instantaneous injection of soot … which is a strong absorber of solar radiation.” The resulting “hundred to thousand fold increase in atmospheric soot concentration would prevent sunlight from reaching the surface over those latitudes wherever substantial amounts of the smoke spread.” While the scenarios that could produce soot concentrations were uncertain, they indicated the “potential for substantial impacts on the hemispheric, and perhaps global, radiation balance and climate.” Thus, McCracken estimated that nuclear war could produce “substantial cooling … that would last weeks to months over most continental regions of the Northern Hemisphere.” This finding, significant cooling if not necessarily a deep freeze, would inform his later work on the subject. Doc-3 Document 3 Letter from Michael McCracken to Herbert Friedman, Commission on Physical Sciences, Mathematics, and Resources, National Research Council, 21 December 1983 Dec 21, 1983 Source Department of Energy FOIA Release In early 1983, while the TTAPS authors was preparing their Science article and presenting their findings, the Department of Defense tasked the National Research Council (the operating arm of the National Academy of the Sciences) to study the “possible atmospheric effects of nuclear war." The Council tasked two committees, a Committee on the Atmospheric Effects of Nuclear Explosions and a Commission on Physical Sciences, Mathematics, and Resources, to prepare a report. By late 1983, they had prepared a draft that they shared with external reviewers for feedback. Comments by Livermore’s Michael MacCracken have been released and illustrate an aspect of the peer-review process involved in the production of such studies. The text that MacCracken was commenting on is unavailable, but his serious and encouraging observations showed a collegial approach. Having no doubt that a major nuclear war could have “potentially very severe derivative consequences,” McCracken nevertheless found that the report did not “describe consistently the uncertainties and underlying assumptions regarding our present knowledge” of those effects. He was especially concerned about emissions from fires, optical properties of smoke, and climatic effects. For example, with respect to the latter, he argued that “we have so far only the very crudest indications of what will occur.” Doc-4 Document 4 Defense Nuclear Agency, Atmospheric Effects Division, “Global Effects of Nuclear War,” Briefing, February 1984, unclassified, Jan 31, 1984 Source FOIA Release by Defense Threat Reduction Agency (DTRA) The Defense Nuclear Agency, which was responsible for surveying weapons effects, was initially reluctant to support a comprehensive research effort.[11] But seeing “serious potential for severe consequences” from a large-scale nuclear exchange, and also “very large uncertainties” about the impact, DNA initiated a study to establish more certain knowledge. Besides seeking to develop a “reasonable predictive capability” to determine the effects, DNA also wanted to establish a “scientific basis” for gauging the impact on the climate and the environment. Interestingly, one of the charts [PDF p. 15] includes the phrase “atmospheric trauma” to characterize the cooling impact of the smoke produced by nuclear explosions. Doc-5 Document 5 Memorandum of Conversation, “Summary of President’s Meeting with British Opposition Neil Kinnock,” 14 February 1984, Secret Feb 14, 1984 Source Declassified Documents Reference Service The problem of nuclear winter briefly emerged in a talk between Reagan and British Labor Party leader and nuclear critic Neil Kinnock. The two had a friendly discussion, with each arguing for their positions, although Kinnock credited the recent U.S “build-down” position and both agreed on the need to prevent further nuclear proliferation. Kinnock mentioned the “widely discussed” idea of nuclear winter in his comments on the danger of nuclear proliferation, and Reagan later acknowledged that a “‘nuclear winter’ was theoretically possible.” Doc-6 Document 6 Lawrence Livermore Laboratory, “Global Effects of Nuclear War Study Project – First Quarterly Report January-March 1984,” Prepared by George F. Bing, 18 May 1984, unclassified May 18, 1984 Source FOIA Release by DTRA Elements of the Department of Energy such as Lawrence Livermore Laboratory were investigating “nuclear winter” before it became a public issue. Stimulated by recent research on the possible environmental impact of nuclear war, especially by the TTAPS group and a 1982 article by Paul Crutzen and John Birks, scientists at Livermore, including Michael McCracken, had begun a full research program by late 1983. This report provides useful background on previous investigations starting with a 1945 study on the “Ignition of the Atmosphere with Nuclear Bombs," the atmospheric fallout research of the 1950s, and a 1975 National Academy of Sciences study on the global effects of nuclear war. With the problem of soot and smoke already highlighted by recent publications, Livermore initiated a major research program directed by Michael May involving six tasks, including nuclear war scenarios, fire ignition, “microphysics and chemistry” of material injected into the atmosphere, and atmospheric modeling. For example, with respect to war scenarios, LLNL would investigate the “fuel loading and fire potential of typical targets,” especially cities. This report provides details of the ongoing work on the six tasks. Doc-7 Document 7 Letter from Michael McCracken to Herbert Friedman, Commission on Physical Sciences, Mathematics, and Resources, National Research Council, 5 September 1984, unclassified Sep 5, 1984 Source FOIA Release by DOE As the NAS prepared its report (see related item, Document 3), Michael MacCracken provided more detailed observations on the latest draft. His comments were again detailed and prefaced with congratulations: the draft is “greatly improved and should be issued.” But he expressed some criticism, for example, that the text had underplayed “the potential interactions between the various individual influences (smoke, dust, and chemistry).” Doc-8 Document 8 Lawrence Livermore Laboratory, “Global Effects of Nuclear War Study Project – Second Quarterly Report April-June 1984,” Prepared by George F. Bing, 28 September 1984, unclassified Sep 28, 1984 Source FOIA Release by DTRA This report provides a detailed account of the follow-up of the Livermore task groups studying aspects of the nuclear winter problem. For its work, the atmospheric modeling group was using Oregon State University’s Global Circulation Model (GCM) (which would soon be used to track climate change). In addition to the work that Livermore was conducting, the White House science adviser had asked the National Oceanic and Atmospheric Administration (NOAA) to develop a national plan, to be completed in September, for five years of research. Moreover, the Defense Science Board had established a small task force to study “Atmospheric Obscuration.” Michael May and others with the lab had also attended conferences and gave presentations in London and the Soviet Union. Doc-9 Document 9 Director of Central Intelligence, Interagency Intelligence Assessment, “The Soviet Approach to Nuclear Winter,” NI IIA 84-10006, December 1984, Secret, Excised copy Dec 1, 1984 Source CIA FOIA Website While U.S. and other scientists were advancing their initial findings about nuclear winter, Soviet officials and researchers began making similar claims.[12] U.S. intelligence community analysts were not sure how seriously the Soviet leadership was taking the subject but believed that it “will remain interested” because of its “profound implications” for their strategic position. According to the analysts, Soviet nuclear winter research was derivative and used by political leaders to justify their positions on nuclear weapons. So far, Soviet science had not made important advances in nuclear winter research or even developed “realistic Nuclear Winter climate modeling,” in part because of “limited computer capabilities.” “Even the fastest Soviet scientific computer, the El’brus-1, is still less than one-tenth the effective speed of a Cray.” Crays were then the world’s fastest computers. The report was scornful of Soviet research as “fall[ing] far short of normal scientific standards” and amounted to “more replication than verification” of research findings elsewhere “because it lacks original Soviet data or models.” So far, U.S. intelligence had not gleaned any information on secret Soviet research on nuclear winter. The U.S. had new intelligence from a recent defector, but information on the “Soviet Nuclear Winter Network” in this report has been withheld in its entirety. The analysts suspected that “officials in the weapons development structure” were following the work being done at the Soviet Academy of Sciences. Soviet nuclear planners would want to “know to what extent their strike plans and US retaliatory strikes would lead to adverse consequences in the USSR.” If the Soviets ever put any significant resources for research into the NW problem it has not been disclosed.[13] Whatever was going on behind the scenes, the analysts argued that the Soviets found it politically beneficial to trumpet concern about nuclear winter. However, nuclear winter played out politically and diplomatically, the analysts did not foresee that it would produce “any changes to Soviet nuclear weapons policies or programs” because the “scientific evidence is not yet convincing.” Yet, if Moscow came to “accept Nuclear Winter effects as both credible and profound, it could lead to serious contradictions between these new considerations, on the one hand, and Soviet doctrine and weapons employment policies on the other.” A puzzle in the story of Soviet nuclear winter research is the disappearance of physicist Vladimir Aleksandrov. In 1985, while in Madrid for an international conference, he vanished without a trace. The case was never solved.[14] Doc-10 Document 10 Memorandum from J. [Joseph] B. Knox, Director, Atmospheric and Geophysical Sciences Division, Lawrence Livermore Laboratory, to Nuclear Effects or Global Effects Distribution [List], “The Prepared Release Statement from the NAS Study -- “The Effects on the Atmosphere of a Major Nuclear Exchange,” 18 December 1984, unclassified, annotated copy Dec 18, 1984 Source DOE FOIA Release During a visit to Washington, Joseph Knox of LLNL had acquired a copy of the “prepared release,” the summary and conclusions, for the NRC/National Academy of Sciences study on nuclear winter. On the text, he made a number of marginal comments, which he acknowledged to the readers of his cover memo, might be read as conveying the “belief [that] the report could have been better.” But he was far more positive: “I am relieved that the NAS report is as good as it is.” He remained concerned that some of the uncertainties about smoke and soot emissions from fires “were deemphasized a bit.” The NRC report issued a few weeks later avoided definitive language or quantitative conclusions, but the committee found that a nuclear exchange involving 6500 megatons (half of the world’s stockpile) could have “long-term climatic effects with severe implications for the biosphere.” The nuclear exchange would “insert significant amounts of smoke, fine dust, and undesirable chemical species into the atmosphere,” and the “depositions could result in dramatic perturbations of the atmosphere lasting over a period of at least a few weeks.” There was a “clear possibility that great portions of the land areas of the northern temperate zone (and a larger segment of the planet) could be severely affected,” with possible effects including “major temperature reductions (particularly for an exchange that occurs in the summer) lasting for weeks, with subnormal temperatures persisting for months.” Uncertainties notwithstanding, the report thus suggested even greater danger from nuclear war. Doc-11 Document 11 J[eremiah] J. Gertler, “Some Policy Implications of Nuclear Winter,” RAND Corporation, January 1985 Jan 1, 1985 Source DTIC online collections Analysts at the RAND Corporation were among those in the defense establishment who looked at the nuclear winter problem. Jeremiah Gertler was disturbed that some commentators had concluded that nuclear winter had no immediate implications for policy because it was just another “horror” or as the “ultimate deterrent” it did not require compensatory action or was unproven and not worth considering. After reviewing the TTAPS analysis of nuclear winter, Gertler concluded that, even if the theory could not be proven, if it became “widely accepted” or remained “unproven,” it had policy implications that needed to be considered. Gertler’s paper focused on several problems. For example, nuclear winter posed serious challenges to the credibility of U.S. deterrence. Popular acceptance of the theory could give NATO allies “much greater reason to doubt our willingness to defend them with nuclear weapons.” That U.S. allies, the U.K. and France, had their own nuclear forces and the capacity to “initiate a nuclear winter” could also have a “detrimental impact on the future of the NATO alliance.” Gertler suggested fixes to U.S. strategic attack policy that could reduce nuclear winter effects, for example, by avoiding highly combustible cities, using lower-yield weapons, earth penetrators, and enhanced radiation weapons (“neutron bombs”), and by making high altitude detonations that would have an electro-magnetic pulse effect. Moreover, if policymakers assumed that nuclear winter was possible, in the event of a nuclear crisis National Command Authorities needed an estimate of the “boomerang effect of each use of nuclear weapons” and “the likely effects on the United States of every given detonation before they issue orders.” In terms of comparative conduct, if both Moscow and Washington believe that an unsurvivable nuclear winter could occur, “the constraints on both nations' behavior should be similar.” If one or the other government, however, did not take nuclear winter into account, it might be “less restrained in its nuclear-use policies than one that does, “as it might believe that a nuclear war could be fought and won.” Doc-12 Document 12 Secretary of Defense Caspar W. Weinberger, The Potential Effects of Nuclear War on the Global Climate, A Report to the U.S. Congress, March 1985 Mar 1, 1985 Source Nuclear Winter, Joint Hearing before the Committee on Science and Technology and the Committee on Interior and Insular Affairs, U.S. House of Representatives, March 14, 1985, (Washington, D.C: U.S. Government Printing Office 1985), 159-179 In contrast to Gertler’s report for RAND (Document 10), the Pentagon’s nuclear winter report sent to Congress over the signature of Defense Secretary Caspar Weinberger in March 1985, was, as Lawrence Badash put it, “cheeky” in arguing that, even if the nuclear winter thesis was correct, it required no change in U.S. nuclear policy. Acknowledging the possibility that nuclear war could induce climate change, the Weinberger report emphasized the uncertainties: “for any major nuclear war, some decrease in temperature may occur over at least the northern mid-latitudes. But what this change will be, how long it will last, what its spatial distribution will be, and, of much more importance, whether it will lead to effects of equal or more significance than the horrific destruction associated with the short-term effects of a nuclear war, and the other long-term effects such as radioactivity, currently is beyond our ability to predict, even in gross terms.”[15] Much of the report was descriptive of research programs under way and some of it was argumentative, with some criticism focused on the TTAPS paper and its one-dimensional model, even though subsequent research had gone beyond it. The Pentagon argued that the nuclear winter theory did not require any change in the U.S. nuclear posture: deterrence policy, including the Strategic Defense Initiative, were “fundamentally sound.” The report acknowledged that “reducing unwanted damage must be an important feature of our policy.” Thus, the U.S. had reduced the total number of its nuclear weapons, cut the total yield of the stockpile, and had been developing more accurate nuclear and non-nuclear systems. While reform of nuclear targeting procedure was underway at the Defense Department, it was actually not until the late1980s that a serious effort began to scale down the number of nuclear weapons in U.S. war plans and to reduce the level of destructiveness.[16] For its chief Senate sponsor, the Pentagon report was a letdown. Senator William Cohen (R-ME), who had requested a detailed and thorough evaluation of the nuclear winter problem, pronounced that “In view of what I asked for, it's unlikely that they could have made an evaluation in 17 pages.” It had not responded to the law, did not discuss the possible impact of nuclear winter on military operations, and evaded the required full discussion of biological or environmental effects. White House science adviser George Keyworth found the report to be “mostly mush.”[17] The Pentagon produced another report the following year, which key Senators also found wanting, but it is not publicly available. [18] Doc-13 Document 13 Michael MacCracken, “Global Atmospheric Effects of Nuclear War,” Lawrence Livermore Laboratory, Energy and Technology Review, May 1985 May 1, 1985 Source University of Kansas Libraries (interlibrary loan) The reports that the various task groups prepared at Livermore Laboratory (described in Documents 5 and 7) are unavailable, but in an LLNL publication Michael MacCracken wrote this review of the research on fire, smoke, and climate. An innovation he employed was the use of three-dimensional models “to address some of the shortcomings in the early climate calculations.” The models included the Oregon State University General Circulation Model (see Document 8) and a model developed by the Lab, GRANTOUR, which could calculate the movement of smoke particles and the processes that influenced their concentration and distribution. Both the GCM and GRANTOUR models could be “coupled in a fully interactive manner.” With the TTAPS study focusing on urban targets, Livermore was working with DNA to look at target scenarios in detail. Some targets, such as ICBM sites in prairies, would not generate much fire, while “the proximity of military targets to developed areas and forests would … alter the number and kinds of fires started.” With its modeling efforts, LLNL could forecast the distribution of smoke during the days and weeks following a nuclear war that injected 150 teragrams (150 million tons) of smoke into the troposphere. One conclusion was that “our interactive simulations predict relatively large decreases in surface temperatures for several geographical regions. Because these sharp temperature drops start from summer rather than global-average conditions, however, we do not find indications of the extended deep freeze predicted by TTAPS.” That finding was not meant to be predictive: the recent work was in the nature of “sensitivity studies of what processes are important in determining the potential climatic perturbation of large amounts of smoke in the atmosphere.” MacCracken concluded that much more effort was necessary to “understand whether substantial cooling is likely or is a remote possibility.” Doc-14 Document 14 U.S. General Accounting Office Report to Congress, Nuclear Winter: Uncertainties Surround the Long-Term Effects of Nuclear War, March 1986 Mar 1, 1986 Source GAO website Taking an even-handed approach to the nuclear winter problem, the GAO delivered a report to Congress that assessed it as a “plausible theory with numerous uncertainties in critical areas such as war scenarios, fire research, and climate modeling.” Exemplifying the impartial approach was the assessment of the original TTAPS paper: Noting that TTAPS had been subject to various criticisms (e.g., for using annually averaged temperatures and neglecting heat transfer from oceans to land) and the uncertainties about physical and chemical effects, GAO nevertheless found that the authors were “successful in focusing attention on a potentially important phenomenon and giving added support for studying the nuclear winter theory.” The GAO looked closely at the state of nuclear winter research and its prospects. As noted, it pointed to areas of uncertainty where further research was necessary, such as nuclear war scenarios, fire characteristics, smoke production and transport, effects from dust, toxic chemicals and gases, and the biological/agricultural effects. Improvements in computer modeling, which necessarily require high-speed machines, was an important research area but was limited by lack of data on smoke and fire. “Until scientists receive more accurate data to apply to their computer climate models and improve their software to simulate atmospheric responses more accurately, modeling results will only show a plausible range of nuclear winter effects under strictly prescribed conditions.” For example, more research was essential to “reliably model how long a smoke cloud would last if the particles were injected into the stratosphere where there is no moisture condensation to rapidly remove them.” To develop a plan for further research, the director of the National Climate Program Office of the National Oceanic and Atmospheric Administration (NOAA) chaired an Interagency Research Program (IRP), which identified priorities and recommended funding levels for the various agencies. According to the GAO, for fiscal year 1986 the IRP provided only $2 million in new funding beyond the $3.5 million that had had already been slated. Although the NOAA-chaired committee had discussed the possibility of a $50 million, 5-year program the final report included no proposals for future funding levels. The fairness of the GAO report drew the ire of the White House Office of Science and Technology Policy (OSTP). According to the GAO, “OSTP expressed the view that the report, in its discussion of policy issues, was giving more validity to the nuclear winter theory than was warranted and suggested the tenor of the report be changed.” The GAO retorted that “it does not agree.” OSTP also wanted GAO to delete the discussion of funding options, citing a “nondisclosure proviso,” but GAO refused, arguing that the information was widely known. Indeed, a 1985 article in Science had disclosed that $50 million had been under consideration .but that federal officials were reluctant to “extract the new funds from ongoing programs” and that George Keyworth, the White House science adviser was loath to “press the issue hard enough.”[19] Doc-15 Document 15 Committee on Interagency Radiation Research and Policy Coordination, Science Panel Report No. 5, Review of SCOPE 28 Report on Environmental Consequences of Nuclear War: Volume II: Ecological and Agricultural Effects, March 1988 (Washington, D.C.: Office of Science and Technology Policy) Mar 1, 1988 Source Department of Agriculture Library (Greenbelt, MD) At the request of the Department of Agriculture, a U.S. government interagency committee sponsored a review of some of the findings of a two-volume report, The Environmental Consequences of Nuclear War, published in 1985 by the Scientific Committee on Problems of the Environment (SCOPE) part of the International Council of Scientific Unions (ICSU) (now the International Council for Science).[20] Some of the TTAPS authors, such as Richard Turco, contributed to the SCOPE report as did Michael MacCracken and Paul J. Crutzen. The first volume had focused on the physical and atmospheric effects of nuclear war while volume two looked at the ecological and environmental impact. The SCOPE report did not use the term nuclear winter, but it nevertheless treated atmospheric perturbations caused by mass fires as integral to the terrible devastation along with the blast and radiation effects. Thus, the authors found that the smoke and soot produced by a major nuclear war could significantly reduce sunlight and produce major drops in temperature. According to Volume II of the SCOPE report, the effects of a nuclear war could disrupt agricultural production to the point where those who survived the “acute phase,” where smoke drastically reduced sunlight and temperature, would “starve during the chronic phase.” While the authors carefully qualified their conclusions, pointing to the limits of the models, they noted that even small changes in temperature could have a devastating impact on agriculture in the Northern Hemisphere. It was such findings that the Department of Agriculture wanted investigated. The Committee on Interagency Radiation Research and Policy, set up by the White House in 1984, established a special task group of agricultural and meteorological experts from universities and government to review the findings of Volume II. The project team did special simulation studies based on models of corn and soybean growth, which helped lead them to the conclusion that there “is a high chance of complete crop failure if temperatures drop by 15°C even for one month during a crop season, as far south as 36°N latitude.” The report agreed with the SCOPE finding that smaller changes in temperature could cause crop failure at higher latitudes. Further, they agreed that the SCOPE report on Volume II “does present a wide range of possible post-nuclear war catastrophes in our life support system” and “clearly establishes the probability of mass starvation for the surviving populations as a direct consequence of nuclear attack.” Yet, while finding that the SCOPE report’s methodology was “sound” the task group also concluded that it understated the effects of nuclear war on agriculture. Pointing to areas that should have received additional emphasis, they observed that the destruction of dams would cause “loss of large areas of irrigated agricultural land” while the destruction of the U.S. food and agriculture infrastructure would cause “severe disruption of production, processing, and distribution.” In their executive summary, the authors found that “the worst case scenario in Volume II may be a gross underestimation of the likely effects of a nuclear war on human populations.” That White House’s science advisers had authorized this review of the SCOPE report is interesting in itself, and that its findings supported nuclear winter theories was also important. Yet, for reasons unknown, this report received no notice at the time, with apparently no publicity from the White House, although it would be cited in studies by experts. Notes for Update [A] For the origins of the TTAPS study and a collective biography of the authors, see Matthias Dörries, “The Politics of Atmospheric Sciences: ‘Nuclear Winter’ and Global Climate Change,” Osiris 26 (2011): 208-219. [B] . Edward Teller, “Widespread After-Effects of Nuclear War,” Nature 310 (1984): 621-624. [C] . Dörries, “The Politics of Atmospheric Sciences,” 219-220. See also Andrew J. Ross, “An Icy Feud in Planetary Science: Carl Sagan, Edward Teller, and the Ideological Roots of the Nuclear Winter Debates, 1980-1984,” Historical Studies in the Natural Sciences (2022) 52 (2022): 190–222. Notes for Original Posting [1]. For a few recent examples, see Joshua Coupe et al., “Nuclear Niño Response Observed in Simulations of Nuclear War Scenarios,” Nature, 22 January 2021; “Smoke from Nuclear War would Devastate Ozone Layer, Alter Climate,” Science Daily, 13 October 2021; Robinson Meyer, “On Top of Everything Else, Nuclear War Would Be a Climate Problem,” The Atlantic, 9 March 2022; and Christopher Colletta, “Blundering into a Nuclear War in Ukraine: A Hypothetical Scenario,” 18 March 2022, NTI. [2]. R. P. Turco, O. B. Toon, T. P. Ackerman, J.B. Pollack, and C. Sagan, “Nuclear Winter: Global Consequences of Multiple Nuclear Explosions,” Science 222 (23 December 1983): 1283-1292. [3]. For an informative and systematic account of nuclear winter theory, its development, promulgation, and reception, see Lawrence Badash’s invaluable, A Nuclear Winter’s Tale: Science and Politics in the 1980s (Cambridge: MIT Press, 2009). [4]. Badash, A Nuclear Winter’s Tale, 58. [5]. Ibid, 125. [6]. Ibid, 204. [7]. Ibid, 148; George W. Rathjens and Ronal H. Siegel, “Nuclear Winter: Strategic Significance,” Issues in Science and Technology 1 (1995): 7-11. Commenting on Rathjens’ demand for a more precise study, Badash observed that “many scientists publish early data on a discovery, fully expecting that they will later be refined.” [8]. Badash, A Nuclear Winter’s Tale, 163. [9]. Turco et al, “Climate and Smoke: An Appraisal of Nuclear Winter,” Science 247 (January 12, 1990): 166-176; Stephen J. Ghan, “Chronic Climactic Effects of Nuclear War,” Atmospheric Environment 25A (1991): 2615-2625; Alan J. Robock, Luke Oman, and Georgiy L. Stenchikov, “Nuclear Winter Revisited with a Modern Climate Model and Current Nuclear Arsenals: Still Catastrophic Consequences,” Journal of Geophysical Research 111 (2007): 1-14; Tom Yutsman, “Nuclear Winter Researcher: Study of Wildfires Confirms Dire Climate Risk From Even a ‘Small’ Nuclear War,” Discover Magazine, 8 August 2019. This article included comments by Michael MacCracken who emphasized uncertainties but acknowledged the risks. [10]. For Brode, TTAPS, and the Pentagon's decision making on a computer program to estimate firestorms, see Lynn R. Eden, Whole World on Fire: Organizations, Knowledge, and Nuclear Weapons Devastation (Ithaca: Cornell University Press,2004) , 238-242, and 271-277. [11]. Badash, A Nuclear Winter’s: Tale, 139. [12]. Later, one Soviet scientist asserted that Soviet military experts had reached similar findings during the 1970s. See comments by Dr. Vitalii Nikolaevich Tsygichko, made during an interview with John Hines, later published in a BDM report on Soviet Intentions 1965-1985. [13]. In a Nuclear Winter’s Tale, at page 226, Badash characterized the Soviet effort as one of “limited capabilities, constrained efforts, and minimal results.” [14]. Ibid, 226-227. [15]. Ibid. 163. [16]. Lee Butler, Uncommon Cause: A Life at Odds with Convention, Volume II; The Transformative Years (Outskirts Press, 2016), 6-16. [17]. Wayne Biddle, “Pentagon Agrees Nuclear Warfare Could Block Sun, Freezing Earth,” The New York Times, 2 May 1985; Badash, A Nuclear Winter’s Tale, 165-167; Badash, A Nuclear Winter’s Tale, 163-165. [18]. Badash, A Nuclear Winter’s Tale, 288-289. [19]. R. Jeffrey Smith, “’Nuclear Winter’ Faces Budgetary Chill,” Science 227 (22 February 1985): 924-925. See also Badash, A Nuclear Winter’s Tale, 162. [20]. Mark A. Harwell and Thomas C. Hutchinson, et al., SCOPE 28 Environmental Consequences of Nuclear War, in two volumes (Chichester: John Wiley & Sons, 1985). Badash discussed the SCOPE study and the CIRRP review at pages 206-215 and 284-285 in A Nuclear Winter’s Tale.