nuclear winter

nuclear winter, theory holding that the smoke and dust produced by a large nuclear war would result in a prolonged period of cold on the earth. The earliest version of the theory, which was put forward in the early 1980s in the so-called TTAPS report (named for last initials of its authors, Richard P. Turco, Owen B. Toon, Thomas P. Ackerman, James B. Pollack, and Carl Sagan), held that the ensuing low temperatures and prolonged periods of darkness would obliterate plant life and seriously threaten the existence of the human species. Later models, which took into account additional variables, confirmed the basic conclusions of the TTAPS report and suggested that the detonation of 100 megatons (the explosive power of 100 million tons of TNT) over 100 cities could produce temperature drops ranging from 5 to 15 degrees.

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nuclear winter

Environmental devastation that some scientists contend would result from a nuclear war. The basic cause, as hypothesized, would be huge fireballs created by exploding nuclear warheads, which would ignite great fires (firestorms). Smoke, soot, and dust would be lifted to high altitudes and driven by winds to form a uniform belt encircling the Northern Hemisphere. The clouds could block out all but a fraction of the Sun's light, and surface temperatures would plunge for as much as several weeks. The semidarkness, killing frosts, and subfreezing temperatures, combined with high doses of radiation, would interrupt plant photosynthesis and could thus destroy much of the Earth's vegetation and animal life. Other scientists dispute the results of the original calculations, and, though such a nuclear war would undoubtedly be devastating, the degree of damage to life on the Earth remains controversial.