Nuclear Winter:

Uncertainties Surround the Long-Term Effects of Nuclear War

NSIAD-86-62: Published: Mar 27, 1986. Publicly Released: Mar 27, 1986.

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GAO reviewed the scientific and policy implications of nuclear winter, including relevant literature and discussions with scientists, researchers, and policy analysts to provide Congress with: (1) an overview of the science of nuclear winter; (2) pertinent information for considering policy implications; and (3) the status of U.S. research.

Nuclear winter is the term used to describe the potential long-term climatic and environmental effects of nuclear war caused by the injection of soot, smoke, and dust into the atmosphere and the associated dramatic reduction of surface temperatures. GAO noted that a 1984 Department of Defense study assessing the nuclear winter theory: (1) stressed the many uncertainties in the theory's assumptions; (2) found the theory plausible and recommended further research; (3) could not quantify the potential long-term consequences; and (4) asserted that nuclear war analyses should consider nuclear winter implications. Current research has identified nuclear winter as a plausible theory with numerous uncertainties in such critical areas as war scenarios, fire research, and climate modelling. GAO found that: (1) war scenarios will remain uncertain because of the uncertainty of such critical warfighting variables as targets, warheads, weapons, and weather conditions; (2) present research has produced little information on a nuclear war's fire and smoke effects on sunlight; and (3) computer models have limited accuracy in representing physical laws of nature and the atmospheric disturbances integral to war. The administration's new Interagency Research Program ties together ongoing efforts at various government laboratories; however, although future funding and research are contemplated, the formal plan does not contain the necessary interagency controls. Because of a lack of consensus regarding defense policy implications, further analysis in this area should be fostered.

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