Nuclear Winter and the End of the Arms Race: Carl Sagan Interview (1991)

Nuclear winter (also known as atomic winter) is a hypothetical climatic effect of countervalue nuclear war. Models suggest that detonating dozens or more nuclear weapons on cities prone to firestorm, comparable to the Hiroshima of 1945, could have a profound and severe effect on the climate causing cold weather and reduced sunlight for a period of months or even years by the emission of large amounts of the firestorms smoke and soot into the Earth's stratosphere. Similar climatic effects can be caused by comets or an asteroid impact, also sometimes termed an impact winter, or by a supervolcano eruption, known as a volcanic winter. During the early 1980s, Fidel Castro recommended to the Kremlin a harder line against Washington, even suggesting the possibility of nuclear strikes. The pressure stopped after Soviet officials gave Castro a briefing on the ecological impact on Cuba of nuclear strikes on the United States.[60] In an interview in 2000, Mikhail Gorbachev, in response to the comment "In the 1980s, you warned about the unprecedented dangers of nuclear weapons and took very daring steps to reverse the arms race," said "Models made by Russian and American scientists showed that a nuclear war would result in a nuclear winter that would be extremely destructive to all life on Earth; the knowledge of that was a great stimulus to us, to people of honor and morality, to act in that situation."[61] As the implications of nuclear winter began to be taken seriously in the late 1980s, military analysts turned their attention to the development of nuclear warheads that would explode at low altitudes and cause less thermal radiation ignited fires, thus reducing the likelihood of a nuclear winter. The TTAPS paper had described a 3000 MT counterforce attack on ICBM sites; Michael Altfeld of Michigan State University and political scientist Stephen Cimbala of Pennsylvania State University argued that smaller, more accurate warheads and lower detonation heights could produce the same counterforce strike with only 3 MT and produce less climatic effects, even if cities were targeted, as lower fuzing heights, such as surface bursts, would limit the range of the burning thermal rays due to terrain masking and shadowing, while also temporarily lofting far more radioactive soil into the atmosphere. Therefore as a consequence of attempting to limit the target fire hazard by reducing the range of thermal radiation with fuzing for surface bursts, this will result in a scenario were the far more concentrated, and therefore deadlier, local fallout that is generated following a surface burst forms, as opposed to the comparatively dilute global fallout created when nuclear weapons are fuzed in air burst mode.[62][63] Altfeld and Cimbala also suggested that belief in the possibility of nuclear winter has actually made nuclear war more likely, contrary to the views of Sagan and others, because it has inspired the development of more accurate, and lower explosive yield, nuclear weapons. http://en.wikipedia.org/wiki/Nuclear_winter