" In 2008, some of the scientists who modeled the original 1983 nuclear winter scenario investigated the likely result of a theoretical regional nuclear war between India and Pakistan, a war they postulated to involve only 100 Hiroshima-scale nuclear weapons, yielding a total of only 1.5 megatons—no more than the yield of some single warheads in the U.S. and Russian arsenals. They were shocked to discover that because such an exchange would inevitably be targeted on cities filled with combustible materials, the resulting firestorms would inject massive volumes of black smoke into the upper atmosphere which would spread around the world, cooling the earth long enough and sufficiently to produce worldwide agricultural collapse. Twenty million prompt deaths from blast, fire, and radiation, Alan Robock and Owen Brian Toon projected, and another billion deaths in the months that followed from mass starvation—from a mere 1.5-megaton regional nuclear war. "

― Richard Rhodes , The Making of the Atomic Bomb