NUCLEAR WINTER

noun (Environment) (War and Weaponry) A prolonged period of extreme cold and darkness which, according to some scientists, would be a global consequence of a nuclear war because a thick layer of smoke and dust particles in the atmosphere would shut out the sun's rays. Etymology: Formed by compounding: an artificial winter caused by a nuclear conflict. History and Usage: The theory of the nuclear winter was formulated by five American scientists, originally for a conference in Washington DC in October-December 1983, and popularized particularly by one of them, Carl Sagan, who attributes the coinage to another, Richard Turco. Writing in the Washington Post's Parade magazine at the time of the Conference, Sagan describes their research as follows: We considered a war in which a mere 100 megatons were exploded, less than one per-cent of the world arsenals, and only in low-yield airbursts over cities. This scenario, we found, would ignite thousands of fires, and the smoke from these fires alone would be enough to generate an epoch of cold and dark almost as severe as in the 5000-megaton case. The threshold for what Richard Turco has called The Nuclear Winter is very low. The lowering of temperatures and lack of light caused by radioactive debris in the atmosphere would, according to this theory, destroy the cycles of nature and ruin crop growth, so that any human survivors of a nuclear exchange would soon run out of food. The theory of the nuclear winter, which was widely discussed in the mid eighties, had an important influence on the military strategy of the superpowers in the second half of the decade. It possibly contributed to the spirit of disarmament which marked the late eighties and early nineties, since it showed a nuclear first strike to be a potentially suicidal act on the part of any country using it, whether or not it led to a nuclear exchange. As the theory was refined it became clear that the global winter scenario was perhaps an exaggeration, and it was supplemented by the idea of a nuclear autumn, in which temperatures would drop significantly, altering the climate with agricultural consequences, but not causing global famine. The underlying principle was raised again in a non-nuclear setting in 1991, when Iraqi troops set light to hundreds of oil wells in Kuwait before leaving at the end of their occupation of the country, and smoke from these oil fires, blocking the sun's rays, had a similar effect on local temperatures and light levels. Downwind from Chernobyl, the first faint chill of a nuclear winter has caused...shivers of anxiety. The Times 20 May 1986, p. 14 Calculations that the aftermath of a nuclear war might resemble 'nuclear autumn' rather than 'nuclear winter' are probably wrong. New Scientist 1 July 1989, p. 43