Global temperature changes after nuclear winter

Diagram obtained by the CIA from the international seminar on nuclear war in Italy 1984. It depicts the findings of Soviet 3-D computer model research on nuclear winter from 1983, and although containing similar errors as earlier Western models, it was the first 3-D model of nuclear winter. The diagram shows the models predictions of global temperature changes after a global nuclear exchange. Top shows effects after 40 days, bottom after 243 days. The co-author of which was nuclear winter pioneer Vladimir Alexandrov.

Nuclear winter (also known as atomic winter) is a hypothetical climatic effect, most often considered a potential threat following a countervalue, or city-targeted, nuclear war. Climate models suggest that the ignition of a hundred or more firestorms that are comparable in intensity to that observed in Hiroshima in 1945 would produce a small nuclear winter. The burning of these firestorms would result in the injection of soot into the Earth's stratosphere, producing an anti-greenhouse effect. The models conclude that the magnitude of this effect from the cumulative products of 100 firestorms would reach sufficient extent to unmistakably alter the global climate, resulting in agricultural losses from the colder weather, and lasting for a period of years.

On the fundamental level, it is known that firestorms can inject sooty smoke into the stratosphere, as each natural occurrence of a wildfire firestorm has been found to "surprisingly frequently" generate minor "nuclear winter" effects. This is somewhat analogous to the frequent volcanic eruptions that inject sulfates into the stratosphere and thereby produce minor volcanic winter effects.

A suite of satellite- and aircraft-based firestorm-soot-monitoring instruments are at the forefront of attempts to accurately determine the lifespan, quantity, injection height, and optical properties of this smoke. Information regarding all of these properties is necessary to ascertain both the length and depth of the cooling effect of firestorms.

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