In English

The atomic origins of climate science

 JILL LEPORREThe Autumn of the Atom: How arguments about nuclear weapons shaped the climate-change debate 
Bipartisan agreement about the future of the planet falls apart not over the bomb but over the climate. Historically, though, they’re inseparable: the weapons and the weather are twisted together, a wire across time, the long fuse to an ongoing debate about the credibility of science, the fate of the Earth, and the nature of uncertainty.

In 1981, when Jimmy Carter delivered his farewell address, part of it was written by Carl Sagan

The Senate had proved unwilling to ratify a treaty that had come out of a second round of Strategic Arms Limitation Talks; Carter wanted to take a moment to reckon with that loss, for the sake of the planet. He turned to Sagan, whose thirteen-part documentary, “Cosmos,” first broadcast in 1980, was the most-watched PBS series ever. “Nuclear weapons are an expression of one side of our human character,” Carter said, in words written by Sagan. “But there’s another side. The same rocket technology that delivers nuclear warheads has also taken us peacefully into space. From that perspective, we see our Earth as it really is—a small and fragile and beautiful blue globe, the only home we have.”

In the 50’s, nuclear weapons shaped environmental science.

Sagan was an astronomer, but early in his career he’d worked on a classified nuclear-weapons project. This was not unusual. Since the Second World War, the military has funded the preponderance of research in the field of physics, and, as historians have now established, a close second was its funding of the earth sciences. Although the environmental movement may not have started until the nineteen-sixties, the research that lies behind it began in the fifties, in the U.S. military. Indeed, the very term “environmental science” was coined in the fifties by military scientists. it was another decade before civilian scientists used the term.
Beginning on the day black rain fell on Hiroshima, nuclear weapons shaped environmental science. In 1949, the U.S. Weather Bureau launched Project Gabriel, a classified meteorological study of weapons and weather. The next year, the Department of Defense, in a study titled “The Effects of Atomic Weapons,” coined the word “fallout.” Researchers considered making the quantity, spread, and duration of fallout the standard measure of the force of a nuclear explosion, but found that approach to be too dependent on the weather. (Instead, they chose blast radius.) They measured and modelled the best weather conditions for explosions and the effects of those explosions on the natural world; they invented and refined tools to detect atmospheric weapons tests conducted by the Soviets; and they investigated the possibility of using nuclear weapons to alter the weather and even the climate of adversaries. Sagan, after finishing his Ph.D. at the University of Chicago, in 1960, worked on a secret military project code-named A119 which had begun in 1958, a year after Sputnik. Sagan was charged with calculating “the expansion of an exploding gas/dust cloud rarifying into the space around the Moon.” The idea was to assess whether a mushroom cloud would be visible from Earth, and therefore able to serve as an illustration of the United States’ military might
Government-funded environmental scientists began noticing something curious: nuclear explosions deplete the ozone layer, which protects the Earth’s atmosphere. This finding related to observations made by scientists who were not working for the military. In the wake of Rachel Carson’s “Silent Spring" published in 1962, the U.S. government formed a number of advisory and oversight organizations, including the Environmental Pollution Panel of the President’s Science Advisory Committee. The panel’s 1965 report, “Restoring the Quality of Our Environment,” included an appendix on “Atmospheric Carbon Dioxide,” laying out, with much alarm, the consequences of “the invisible pollutant” for the planet as a whole. In 1968, S. Fred Singer, an atmospheric physicist who had worked on satellites and was now a Deputy Assistant Secretary of the Interior, organized a symposium on “Global Effects of Environmental Pollution.”

New avenues of research

Changing weapons policy opened new avenues of research. In 1963, the U.S. and the U.S.S.R. signed the Limited Test Ban Treaty, (PTBT), an agreement to stop testing nuclear weapons in the atmosphere. Using longitudinal data to study the ozone, both before and after the test ban, the Berkeley chemist Harold Johnston found that stopping the testing had slowed the depletion. Research into the environmental consequences of nuclear explosions and of other kinds of pollution shared a planetary perspective, a vantage greatly enhanced by the space program; gradually, the meaning of the word “environment” changed from “habitat” to “planet.” The first photograph of the whole Earth was taken in 1972, by the crew of Apollo 17, It became an icon of the environmental movement. It also shaped arguments about arms control.
Nuclear-weapons research was usually classified; other environmental research was not. During the nineteen-seventies, military-funded environmental scientists continued their top-secret research into the environmental effects of nuclear weapons. Given the test ban, these studies relied less on experiments on Earth than on computer models and on empirical findings involving dust on other planets, most notably Mars. (…) In 1974, the director of the U.S. Arms Control and Disarmament Agency (ACDA) asked the National Academy of Sciences to prepare a report on the effects of nuclear explosions on the ozone. That report, “Long-Term Worldwide Effects of Multiple Nuclear Weapons Detonations,” married the logic of nuclear deterrence to the logic of environmental protection, or what might have been called pollution deterrence. Stephen Schneider, a climatologist at the National Center for Atmospheric Research, speculated that the fallout from a nuclear war might make the world colder by blocking sunlight, and that the diminished industrial production in a postwar world could change the climate, too.

Jonathan Schell and SDI

Sagan had by this time become an advocate of nuclear disarmament, a cause that gained a great deal of momentum early in 1982, when The New Yorker published a four-part series by Jonathan Schell called “The Fate of the Earth,” which did for nuclear weapons what Carson had done for chemical pollution: freaked everyone out. That fall, Representative Al Gore, the chair of the Subcommittee on Investigations and Oversight of the House Committee on Science and Technology, convened hearings into “The Consequences of Nuclear War on the Global Environment.” The consequences of nuclear war on the environment, like its consequences on the balance of power, were difficult to prove; most data came from computer models, and from research on other planets. A battle began between those who were willing to place their faith in the speculations of military strategists and those who were willing to place their faith in the speculations of environmental scientists.

Nuclear winter bringing together weapons and the weather
carl sagan finger puppet

What Sagan did next is recounted in a new book by Paul Rubinson, “Redefining Science,” a history of science in a national-security state. The story of Sagan’s campaign against S.D.I., though little remembered, has been told before, in Lawrence Badash’s 2009 book, “A Nuclear Winter’s Tale”; in “Merchants of Doubt,” by Naomi Oreskes and Erik M. Conway, in 2009; and, most richly, in a terrific 2011 journal article by Matthias Dorries. Sagan launched a campaign to warn the world about “nuclear winter”; the very term, as Dorries points out, brought together the weapons and the weather.
Sagan collaborated with four scientists. James Pollack, his first graduate student, had written a dissertation, in 1965, on the greenhouse effect on Venus. Thomas Ackerman had attended Calvin College, a Christian school, as an undergraduate, earned a Ph.D. at the University of Washington, and then worked with Pollack at NASA. (Later, he declined an invitation to work on S.D.I., citing his moral objections as a Christian.) Richard Turco, an atmospheric scientist, was the co-author of a study called “Possible Ozone Depletions Following Nuclear Explosions,” which was published in Nature in 1975, the year that Owen Brian Toon, a graduate student at Cornell, submitted to Sagan a dissertation called “Climatic Change on Mars and Earth.” Sagan decided to use his celebrity to bring the research of these scientists to the broadest possible public audience, as fast as the scientific method allowed—or maybe faster.
Sagan received his training in that world. But that world did not survive Vietnam, or the Love Canal disaster. This much Sagan understood. But what he could not have fully understood were two forces that had gained strength in the nineteen-seventies, both of which were at odds with his neo-Deweyism: a postmodern critique of objectivity, fashionable among intellectuals, artists, and writers; and a conservative movement determined to expose the liberal bent of the academy and of the press. Sagan waded into these waters early in 1983, with a paper he prepared with Turco, Toon, Ackerman, and Pollack. The paper, known by its authorial acronym, TTAPS, used meteorological models derived from the study of volcanoes to calculate the effects on light and temperature of different kinds and numbers of nuclear explosions, factoring in the dust, smoke, and soot produced by the burning of cities; some of the data came from Mars. Moving beyond Jonathan Schell, whose essays had predicted the end of humanity, TTAPS forecast a nuclear winter that might result in the end of all life on the planet.
Sagan was widely resented, and he made some poor decisions, but he was a serious scientist. Despite a number of adjustments, the theory gained widespread scientific acceptance. Declassified documents demonstrate that Navy scientists, for instance, were persuaded by TTAPS. In May, 1984, William Cohen, a Republican senator from Maine, wrote to Reagan about the paper and suggested that the Administration conduct a study. The House Republicans Jim Leach and Newt Gingrich joined their Democratic colleagues Tim Wirth, Buddy Roemer, and Al Gore in proposing a budget amendment mandating a “comprehensive study of the atmospheric, climatic, environmental, and biological consequences of nuclear war and the implications that such consequences have for the nuclear weapons strategy and policy, the arms control policy, and the civil defense policy of the United States.”
Hearings on nuclear winter were held that summer, before a House subcommittee that, Paul Rubinson says, “essentially put deterrence on trial.” If a misfire or an accident would mean the end of all life on the planet, could there really be any strategic argument in favor of a nuclear stockpile? During another round of congressional hearings, Sagan said that he’d give a recent and inconclusive Department of Defense report on nuclear winter a D or “maybe a C-minus if I was in a friendly mood.”
In December, 1984, Reagan’s National Security Council presented the President with a summary of a report on nuclear winter prepared by the National Academy of Sciences. While allowing that the model’s quantitative risk assessment involved uncertainties, the report argued that the model’s calculations suggested “temperature changes of a size that could have devastating consequences” and, with urgency, called on all available agencies and scientists to conduct investigations to narrow the range of uncertainty. Nuclear winter could be debated, but it couldn’t be dismissed.
Nuclear winter did not end the Cold War, but it did weaken the logic of deterrence, and not merely by undermining the idea of a winnable nuclear war. Nuclear winter relied on computer models and projections; its predictions were uncertain. At one point, Richard Perle said that he wished Sagan would go back to his laboratory and stop “playing political scientist.” And that, inadvertently, got to the heart of the matter. However much Sagan might have overreached, his intellectual extravagance was nothing compared with the entirely hypothetical musings and game-theory models of the political scientists and strategists on the basis of whose speculations the United States government spent more than five trillion dollars between 1940 and 1996.
Reagan was himself persuaded by nuclear winter; a nuclear war, he said, “could just end up in no victory for anyone because we would wipe out the earth as we know it.” In the U.S.S.R., nuclear winter energized dissidents. In 1985, when the Soviet physician Vladimir Brodsky was arrested, one of the charges was “transmitting a letter to the Soviet Academy of Sciences requesting greater publicity about the nuclear winter.” Protesters in Moscow’s Gagarin Square chanted, “Tell the truth about the nuclear-winter phenomenon to our people.” Eduard Shevardnadze, the Soviet foreign minister, talked about nuclear winter in a speech at the U.N., and Mikhail Gorbachev alluded to it on another occasion. In 1985, the Federation of American Scientists presented Sagan with an award honoring him as the “Most Visible Member of the Scientific Community on the Planet Earth.” (…). After that year, the number of nuclear weapons in the world began to decline
The biggest consequence of the nuclear-winter debate, though, has had to do not with nuclear-weapons policy but with the environmental movement. In the short term, the idea of a nuclear winter defeated the idea of deterrence.
Critics of climate-change science who ground their argument on uncertainty have either got to apply that same standard of evidence to nuclear-weapons strategy or else find a better argument. Because, as Sagan once put it, theories that involve the end of the world are not amenable to experimental verification—at least, not more than once.

Jill Lepore
Published in the print edition of January 30, 2017, issue, with the headline “Autumn of the Atom.”