“[Here we are on] the Halloween preceding 1984,” Carl Sagan solemnly told a gathering of scientists and reporters in Washington, D.C., “and I deeply wish that what I am about to tell you were only a ghost story, something invented to frighten children for a day. But unfortunately, it is not just a story.”
Thus began a spellbinding tale of doom, delivered in inimitable Sagan fashion. Should nuclear war erupt between the world’s two superpow ers, warned the Cornell University astronomer and popularizer of science, black smoke from cities set ablaze would blot out the sun and cause a long-term cataclysmic drop in the Earth’s temperature.
The scenario was quickly dubbed “nuclear winter,” and for a time it grabbed front-page head lines around the world before eventually fading from public view.
Now the theory is making a comeback. But the latest version is far from being a Halloween horror story....