Nuclear winter is a severe and prolonged global climatic cooling effect that is hypothesized[1][2] to occur after widespread firestorms following a large-scale nuclear war.[3] 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.[4][5] 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,[6] alongside modern observations of natural, large-area wildfire-firestorms.[3][7][8]
^Toon et al. 2007. "the injection height of the smoke is controlled by the energy release from the burning fuel not from the nuclear explosion"., "...smoke plumes deep within the stratosphere over Florida that had originated a few days earlier in Canadian fires, implying that the smoke particles had not been significantly depleted during injection into the stratosphere (or subsequent transport over thousands of kilometers in the stratosphere)."