Nuclear winter is a severe and prolonged global climatic cooling effect hypothesized to occur after widespread firestorms following a nuclear war. The hypothesis is based on the fact that such fires can inject soot into the stratosphere, where it can block some direct sunlight from reaching the surface of the Earth. It is speculated that the resulting cooling would lead to widespread crop failure and famine. When developing computer models of nuclear-winter scenarios, researchers use the conventional bombing of Hamburg, and the Hiroshima firestorm in World War II as example cases where soot might have been injected into the stratosphere, alongside modern observations of natural, large-area wildfire-firestorms.
In an interview in 2000 with Mikhail Gorbachev (the leader of the Soviet Union from 1985–91), the following statement was posed to him: "In the 1980s, you warned about the unprecedented dangers of nuclear weapons and took very daring steps to reverse the arms race", with Gorbachev replying "Models made by Russian and American scientists showed that a nuclear war would result in a nuclear winte
Altfeld and Cimbala also argued that belief in the possibility of nuclear winter would actually make nuclear war more likely, contrary to the views of Sagan and others, because it would serve yet further motivation to follow the existing trends, towards the development of more accurate, and even lower explosive yield, nuclear weapons. As the winter hypothesis suggests that the replacement of the then Cold War viewed strategic nuclear weapons in the multi-megaton yield range, with weapons of explosive yields closer to tactical nuclear weapons, such as the Robust Nuclear Earth Penetrator (RNEP), would safeguard against the nuclear winter potential. With the latter capabilities of the then, largely still conceptual RNEP, specifically cited by the influential nuclear warfare analyst Albert Wohlstetter. Tactical nuclear weapons, on the low end of the scale have yields that overlap with large conventional weapons, and are therefore often viewed "as blurring the distinction between conventional and nuclear weapons", making the prospect of using them "easier" in a conflict.
In an interview in 2000 with Mikhail Gorbachev (the leader of the Soviet Union from 1985–91), the following statement was posed to him: "In the 1980s, you warned about the unprecedented dangers of nuclear weapons and took very daring steps to reverse the arms race", with Gorbachev replying "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."
However, a 1984 US Interagency Intelligence Assessment expresses a far more skeptical and cautious approach, stating that the hypothesis is not scientifically convincing. The report predicted that Soviet nuclear policy would be to maintain their strategic nuclear posture, such as their fielding of the high throw-weight SS-18 missile and they would merely attempt to exploit the hypothesis for propaganda purposes, such as directing scrutiny