Nuclear winter is a theory estimating the global climatic consequences of a nuclear war: prolonged and worldwide cooling and darkening caused by sunlight-blocking smoke and soot entering the atmosphere. During the Cold War after World War II, the concern about nuclear weapons was increasing all over the world. Initially, only the danger of radioactive fallout was recognized, but later also the possible environmental effects of a nuclear war became the subject of several studies. The term nuclear winter was first defined and used by American astronomer Carl Sagan (1934–1996) and his group of colleagues in their 1983 article (later referred to as the TTAPS-article, from the initials of the authors' family names). This article was the first one to take into consideration not only the direct damage, but also the indirect effects of a nuclear war.

The basic assumption during a nuclear war is that the exploding nuclear...