Twenty-five years ago international teams of scientists showed that a nuclear war between the U.S. and the Soviet Union could produce a “nuclear winter.” The smoke from vast fires started by bombs dropped on cit¬ies and industrial areas would envelop the planet and absorb so much sunlight that the earth’s sur¬face would get cold, dark and dry, killing plants worldwide and eliminating our food supply. Sur¬face temperatures would reach winter values in the summer. International discussion about this prediction, fueled largely by astronomer Carl Sa¬gan, forced the leaders of the two superpowers to confront the possibility that their arms race endangered not just themselves but the entire hu¬man race. Countries large and small demanded disarmament.
Nuclear winter became an important factor in ending the nuclear arms race. Looking back later, in 2000, former Soviet Union leader Mikhail S. Gorbachev observed, “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 mo¬rality, to act.”
Why discuss this topic now that the cold war has ended? Because as other nations continue to acquire nuclear weapons, smaller, regional nu¬clear wars could create a similar global catastro¬phe. New analyses reveal that a conflict be¬tween India and Pakistan, for example, in which 100 nuclear bombs were dropped on cities and industrial areas—only 0.4 percent of the world’s more than 25,000 warheads—would produce enough smoke to cripple global agriculture. A regional war could cause widespread loss of life even in countries far away from the conflict.
Nuclear bombs dropped on cities and industrial areas in a fight between India and Pakistan would start firestorms that would put massive amounts of smoke into the upper atmosphere. The particles would remain there for years, blocking the sun, making the earth’s surface cold, dark and dry. Agricultural collapse and mass starvation could fol¬low. Hence, global cooling could result from a regional war, not just a conflict be¬tween the U.S. and Russia. Cooling scenarios are based on computer models. But observations of volca¬nic eruptions, forest fire smoke and other phenome¬na provide confidence that the models are correct.
Source of Information : Scientific American January 2010