A Cold, Dark Apocalypse

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Two new portraits of doomsday add fuel to the arms debate

Nuclear-war scenarios have been so numerous, and portrayed so vividly in movies and on TV for so many years, that it might seem they had lost all power to shock. Not so, at least in the case of a new script formally presented last week at a scientific conference in Washington. To the applause of disarmament enthusiasts, who promptly predicted that many new adherents will now be won over to their cause, the blue-chip conference posited catastrophe for a reason few had imagined: a pitch-dark, bone-chilling "nuclear winter" brought on by the detonation of even less than half the megatonnage in U.S. and Soviet arsenals. The new study, says Randall Kehler, national coordinator of the Nuclear Weapons Freeze Campaign, "cannot be written off as the rhetoric of antinuke activists."

The study is actually two efforts, by cooperating groups of scientists, one headed by Cornell Astronomer and TV Personality Carl Sagan and the other by Stanford Biologist Paul Ehrlich. They presented their findings at the two-day Conference on the Longterm, Worldwide Biological Consequences of Nuclear War. It was attended by some 600 American and foreign scientists and environmentalists and addressed by satellite by four Soviet counterparts in Moscow. Among them: Evgeni Velikhov, vice president of the U.S.S.R. Academy of Sciences. The Soviets said they had independently come to roughly the same conclusions as the Sagan-Ehrlich teams.

Sagan and Ehrlich picked as their "baseline case" a 5,000 megaton war. (One megaton equals 1 million tons of TNT; the explosive power of all strategic nuclear warheads possessed by the U.S. and Soviet Union is thought to total 12,000 megatons.) The results of such a war: a cloud of dust and smoke weighing 1.2 billion tons rapidly envelops the Northern Hemisphere and swiftly swirls into the Southern Hemisphere as well, blocking out 90% or more of the sun's light. Surface temperatures plunge to an average of —13° F and remain below freezing for three months, even if the war is fought in the Northern Hemisphere summer. Nothing can grow; those humans who survive the blast and radiation of the explosions freeze or starve to death.

At best, Ehrlich figures, small bands of hunters and gatherers would be left in the Southern Hemisphere. And life would have difficulty renewing itself even after the dark and cold lifted, because most of the protective layer of ozone in the upper atmosphere would have been burned off. Killer ultraviolet radiation would stream in from the sun, paralyzing even phytoplankton, the one-celled ocean plants that form the base of the ocean's food chain. The effects would be less ghastly—but still catastrophic—if fewer megatons were exploded.