Residents of Earth receive a chilling early Christmas present on December 23, 1983, when a group of scientists including Carl Sagan releases a paper titled “Nuclear Winter: Global Consequences of Multiple Nuclear Explosions.” This publication introduces the concept of nuclear winter, a period of global cold and darkness that could result from a nuclear war.
The paper reported the results of modeling which showed that a war in which multiple nuclear weapons were deployed would have profound effects on the Earth’s atmosphere. The central claim was that nuclear explosions could create a cloud of dust, smoke, ash, and debris large enough to encircle the Earth and significantly lower global temperatures, spreading dangerous amounts of radiation. The authors argued that such an event would endanger all life on Earth, writing “when combined with the prompt destruction from nuclear blast, fires, and fallout and the later enhancement of solar ultraviolet radiation due to ozone depletion, long-term exposure to cold, dark, and radioactivity could pose a serious threat to human survivors and to other species.”
The hypothesis of nuclear winter captured imaginations around the world, and the bleak, cloudy, world it describes has since become a go-to setting for dystopian fiction. The paper arrived at a moment of heightened tensions between the United States and the Soviet Union—just a month before, Soviet diplomats had withdrawn from discussions of a potential arms-control treaty after the U.S. stationed nuclear missiles in West Germany—and presented a vivid depiction of the global calamity that these tensions could bring about.
In the years since its publication, however, other scientists have disputed the paper’s hypothesis, with some going as far as to accuse Sagan of anti-war “propaganda.” The exact number of nuclear explosions it would take to cause a nuclear winter, and the exact nature of the damage to the atmosphere and environment, remain topics of debate, but there is no question that any nuclear explosion, and certainly any nuclear war, would result in major damage to our planet and its inhabitants.