Nuclear Winter

Linus Pauling speaking at a Greenpeace press conference commemorating the twentieth anniversary of the Limited Test Ban Treaty. June 10, 1983.

[Ed Note: This post was researched and written as a result of a request from one of our readers.  If there are specific aspects of Pauling’s life and work that you are interested in learning more about, please do not hesitate to let us know in Comments.]

In a nuclear exchange, which we must try to avoid or to deter, the Russian deaths would probably not exceed ten million. Tragic as such a figure is, the Russian nation would survive. If they succeed in eliminating the United States they can commandeer food, machinery and manpower from the rest of the world. They could recover rapidly. They would have attained their goal: world domination.

– Edward Teller, Foreword to Nuclear War Survival Skills, 1979.

In 1982 executives from several foundations met to discuss what was, at the time, a perceived gap in research and peer-reviewed scholarship on nuclear weapons and their use. While a few studies had addressed the biological impacts of nuclear war, primarily focusing on fallout and radiation, significant research concerning global environmental impact was glaringly absent from relevant discussions. To help fill this void, a group of scientists, including popular astronomer Carl Sagan, began investigating the atmospheric and climatic effects of a full-scale nuclear war.

The paper that resulted from their collaboration, later referred to as the TTAPS study, set in motion an evolution in the scientific perspective on nuclear warfare. In the wake of the TTAPS report, scientists from various backgrounds were brought together to begin advanced study of the issue, beginning with widespread peer review of the TTAPS conclusions, and leading to the organization of several international conferences at which many diverse aspects of this emerging multi-disciplinary topic were discussed.

Out of all this arose a more comprehensive theory of nuclear warfare, which attempted to shift perceptions from genocidal mechanisms to omnicidal ones.  Specifically, supporters of this new paradigm proposed that a world wide nuclear war could destroy nearly all of the life-sustaining biological systems on earth, not just the basic elements required for human civilization.  The ramifications of this frightening notion led to the coining of a new phrase: nuclear winter.

The primary suggestion of nuclear winter theory is that an aggressive international atomic conflict would likely alter the climatic systems of the earth, particularly in the northern hemisphere. Because cities and forests would be ignited by widespread nuclear explosions, the theory asserts that unprecedented amounts of smoke, soot and dust would be propelled high into the atmosphere. This layer of dust and soot would absorb most of the incoming solar radiation at high levels of the atmosphere, thus lowering the temperature of the Earth’s surface and hindering or completely halting photosynthetic processes on a global scale.

Using the dust storms and atmospheric activity on Mars as a reference, Sagan and his associates developed a model of the effect that such a condition could have on the Earth. Their initial estimate suggested that most land temperatures, aside from strips of coastline, could expect to drop to minus-13 degrees Fahrenheit and would stay at that temperature for several months, even during a summer war.

The lack of sunlight and heat on the surface of the planet would have obvious major impacts on agriculture and the ability of the Earth’s biological systems to recover and support human life. Employing a mix of psychiatry, history, religion and biology, proponents of the theory therein encouraged their audiences to question what they viewed to be an overly aggressive strategic nuclear policy being advanced by the world’s political leaders.

The concept of nuclear winter was not without its criticisms, one of the most direct coming in a book by Cresson Kearny titled Nuclear War Survival Skills. With a foreword by Edward Tellerthe “father” of the hydrogen bomb – the book was written to serve as a civil defense manual, providing advice for logical courses of action in the event of a nuclear catastrophe. Most of the information in the book was developed at the Oak Ridge National Laboratory during the Cold War, but Kearny’s critical views on nuclear winter were based primarily on conclusions drawn from another paper, “Nuclear Winter Reappraised.”

While the authors of  “Nuclear Winter Reappraised,” S. L. Thompson and S. H. Schneider, acknowledged the general climatic effects hypothesized by the nuclear winter theory, they also suggested that the overall impact would be much less severe than Sagan and others had predicted. Among other critical observations, Thompson and Schneider emphasized the assertion that a “‘threshold’ existed above which the climatic affects of a nuclear attack would become catastrophic,” in the process strongly suggesting that limited nuclear warfare should still be considered as a viable military tactic. Coining the term “nuclear autumn,” the paper provided skeptics and others with an avenue to reject the nuclear winter theory’s basic and largely undisputed principles.


Linus Pauling, an ardent activist against nuclear testing for more than four decades, chose to remain relatively discrete in his outright use of the term “nuclear winter.” He engaged in sporadic communication with Carl Sagan during the theory’s mainstream exposure, but the topic of nuclear winter was not covered in their correspondence. Pauling likewise owned a copy of the essay collection The Long Darkness: Psychological and Moral Perspectives on Nuclear Winter, in his personal library, but the book does not appear to have been heavily used.

While related sources might be sparse because of his slow retreat from activism in later years, Pauling did demonstrate agreement with the theory’s central tenants during several speeches that he gave throughout the mid-1980s.

In an oft-delivered and highly acclaimed talk titled “The Path to World Peace,” Pauling discussed the effects of world wide atomic war in terms that closely match those used by proponents of the nuclear winter theory. In early versions of the speech, notes can be found on drafts which implicitly relate to the effects of nuclear winter, but do not show up in finished versions of the speech.

By 1983 however, Pauling had revised portions of the speech to include content which directly conforms to the theory’s central tenets. After discussing potential damage to the ozone layer at a conference in British Columbia, Pauling described the effects that fires, ignited by atomic blasts from a nuclear conflict, would have around the Earth:

Almost all forests, houses, and other combustible materials would burn. The amount of smoke and dust thrown up from ground bursts might be enough to prevent sunlight from getting to the surface of the earth for months. We know that species of animals and plants die out under this condition.

Immediately following this point, Pauling shared a theory about the extinction of dinosaurs. Referring to the fossil record, Pauling outlined the hypothesis that a large asteroid collided with Earth during prehistoric times, incinerating tons of rock that were then forced into the atmosphere in the form of dust. This dust cloud, according to the theory, then absorbed the sun’s radiation for a substantial amount of time. Pauling described how the lack of sunlight would have prevented photosynthesis in plants, causing mass extinctions as the effects worked their way up the food chain.

Though similar references are difficult to find in Pauling’s papers, a letter from a student, whose class was visited by Pauling in 1984, demonstrates that Pauling’s reference to the nuclear winter theory was not a one time affair.  In it, the student writes

Your talk at Corte Madera effectively changed my view of nuclear war. Not that I didn’t realize that nuclear war would virtually destroy the world population, but I scoffed at the Nuclear Winter Theory. Your comparison between the meteorite causing the extinction of the dinosaurs and nuclear blasts around the world convinced me that a nuclear winter would occur in the event of a clash between the superpowers involving nuclear weapons.

While it is not clear how much time Pauling spent discussing or thinking about the theory of nuclear winter, his familiarity with and acceptance of its concepts seems evident, and it is clear that he found them important enough to share with both large audiences and classrooms of young people. Though the theory was not the recipient of much public backing from Pauling, and was subject to calculated criticism by others, it has maintained consistent support and recognition well into the current decade.

One Response

  1. Thank you for this interesting follow-up, it is much appreciated.

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