Nuclear Winter from
Produced by Kit Roane Sarah Weiser

Released April 3, 2016
In 1983, scientists gave the world a new reason to fear nuclear war. It had long been assumed that the immediate, direct effects of a nuclear blast would cause a devastating loss of life, and that radioactive fallout would linger. But these scientists stressed that smoke from nuclear-ignited cities might affect something far more remote — the climate around the globe.

What they found was harrowing. Their models showed that smoke from burning cities and forests could loft high into the atmosphere, shrouding the world in a twilight at noon. Freezing temperatures would kill crops, causing mass starvation and social unrest, and possibly lead to the extinction of mankind.

Called Nuclear Winter, this theory became a heated scientific topic, a pawn in Cold War brinksmanship and a lesson in how scientific understanding changes over time. But decades after detente finally ended the Cold War, it is clear that Nuclear Winter continues to raise new questions — not only about the devastation that would follow nuclear war, but also more fundamental ones about man’s ability to alter the earth’s climate, for both good and ill.


Nuclear winter was and is debatable
Russell Seitz
Nature volume 475, page 37 (07 July 2011)

Alan Robock’s contention that there has been no real scientific debate about the ‘nuclear winter’ concept is itself debatable (Nature 473, 275–276; 2011).

This potential climate disaster, popularized in Science in 1983, rested on the output of a one-dimensional model that was later shown to overestimate the smoke a nuclear holocaust might engender. More refined estimates, combined with advanced three-dimensional models (see, have dramatically reduced the extent and severity of the projected cooling.

Despite this, Carl Sagan, who co-authored the 1983 Science paper, went so far as to posit “the extinction of Homo sapiens” (C. Sagan Foreign Affairs 63, 75–77; 1984). Some regarded this apocalyptic prediction as an exercise in mythology. George Rathjens of the Massachusetts Institute of Technology protested: “Nuclear winter is the worst example of the misrepresentation of science to the public in my memory,” (see and climatologist Kerry Emanuel observed that the subject had “become notorious for its lack of scientific integrity” (Nature 319, 259; 1986).

Robock’s single-digit fall in temperature is at odds with the subzero (about −25 °C) continental cooling originally projected for a wide spectrum of nuclear wars. Whereas Sagan predicted darkness at noon from a US–Soviet nuclear conflict, Robock projects global sunlight that is several orders of magnitude brighter for a Pakistan–India conflict — literally the difference between night and day. Since 1983, the projected worst-case cooling has fallen from a Siberian deep freeze spanning 11,000 degree-days Celsius (a measure of the severity of winters) to numbers so unseasonably small as to call the very term ‘nuclear winter’ into question.
“Nuclear winter was and is debatable” by Russell Seitz, July 2011

Additional Resources:

“Nuclear Winter: Global Consequences of Multiple Nuclear Explosions” by Carl Sagan, et al., 1983

“Long-term Biological Consequences of Nuclear War” by Paul R. Ehrlich, et al., 1983

“The Soviet Approach to Nuclear Winter” CIA Interagency Intelligence Assessment, 1984

“The Effects on the Atmosphere of a Major Nuclear Exchange” Committee on the Atmospheric Effects of Nuclear Explosions, National Research Council, 1985

“Global Atmospheric Effects of Nuclear War,”Energy and Technology Review, 1985

“Nuclear Winter Reappraised” by Starley L. Thompson and Stephen H. Schneider, 1986

“Atmospheric and Climatic Consequences of a Major Nuclear War: Results of Recent Research” by G. S. Golitsyn, and M. C. MacCracken, 1987

“Nuclear Winter: Science and Politics” by Brian Martin, 1988

“Nuclear Winter Theorists Pull Back” by Malcolm W. Browne, 1990

“Climate and Smoke: An Appraisal of Nuclear Winter” by Carl Sagan et al., 1990

“Nuclear Winter in the Post-Cold War Era” by Carl Sagan and Richard P. Turco, 1993

“Nuclear Winter Revisited with a Modern Climate Model and Current Nuclear Arsenals: Still Catastrophic Consequences” by Alan Robock, Luke Oman, and Georgiy L. Stenchikov, 2007

Interactive comment on “Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism” by O. B. Toon et al. By M. MacCracken, 2007

Interactive comment on “Climatic consequences of regional nuclear conflicts” by A. Robock et al. By M. MacCracken, 2007

“Environmental Consequences of Nuclear War” by Owen B. Toon, Alan Robock, and Richard P. Turco, 2008

“Nuclear winter was and is debatable” by Russell Seitz, July 2011