People have several incorrect impressions about nuclear winter. One is that the climatic effects were disproved; this is just not true [see sidebar on page 78]. Another is that the world would experience “nuclear autumn” instead of winter. But our new calculations show that the climate effects even of a regional conflict would be wide¬spread and severe. The models and computers used in the 1980s were not able to simulate the lofting and persistence of the smoke or the long time it would take oceans to warm back up as the smoke eventually dissipated; current models of a full-scale nuclear exchange predict a nucle¬ar winter, not a nuclear fall.
Another misimpression is that the problem, even if it existed, has been solved by the end of the nuclear arms race. In fact, a nuclear winter could readily be produced by the American and Russian nuclear arsenals that are slated to re¬main in 2012. Furthermore, the increasing num¬ber of nuclear states raises the chances of a war starting deliberately or by accident. For example, North Korea has threatened war should the world stop its ships and inspect them for trans¬porting nuclear materials. Fortunately, North Korea does not now have a usable nuclear arse¬nal, but it may have one capable of global reach in the near future. Some extremist leaders in In¬dia advocated attacking Pakistan with nuclear weapons following recent terrorist attacks on In¬dia. Because India could rapidly overrun Paki¬stan with conventional forces, it would be con¬ceivable for Pakistan to attack India with nuclear weapons if it thought that India was about to go on the offensive. Iran has threatened to destroy Israel, already a nuclear power, which in turn has vowed never to allow Iran to become a nuclear state. Each of these examples represent countries that imagine their existence to be threatened completely and with little warning. These points of conflict have the potential to erupt suddenly.
The first nuclear war so shocked the world that in spite of the massive buildup of these weapons since then, they have never been used again. But the only way to eliminate the possibil¬ity of climatic catastrophe is to eliminate the weapons. Rapid reduction of the American and Russian arsenals would set an example for the rest of the world that nuclear weapons cannot be used and are not needed.
Under the Strategic Offensive Reductions Treaty, the U.S. and Russia both committed to reduce deployed strategic nuclear warheads down to between 1,700 to 2,200 apiece by the end of 2012. In July 2009 President Barack Obama and Russian president Dmitry Medvedev agreed to drop that range further, to 1,500 to 1,675 by 2016. Although smaller strategic arse¬nals are to be commended, our new results show that even the lower counts are far more than enough to destroy agriculture worldwide, as is a regional nuclear war. If this mother lode of weap¬ons were used against urban targets, hundreds of millions of people would be killed and a whop¬ ping 180 Tg of smoke would be sent into the glob¬al stratosphere. Average temperatures would re¬main below freezing even in the summer for sev¬eral years in major agricultural regions. Even the warheads on one missile-carrying submarine could produce enough smoke to create a global environmental disaster.
The combination of nuclear proliferation, po¬litical instability and urban demographics may constitute one of the greatest dangers to the sta¬bility of society since the dawn of humans. Only abolition of nuclear weapons will prevent a po¬tential nightmare. Immediate reduction of U.S. and Russian arsenals to the same levels as other nuclear powers (a few hundred) would maintain their deterrence, reduce the possibility of nuclear winter and encourage the rest of the world to con¬tinue to work toward the goal of elimination.
President Obama understands this logic. In his first press conference as president, on Febru¬ary 9, 2009, he said, “It is important for the United States, in concert with Russia ... to re¬start the conversations about how we can start reducing our nuclear arsenals in an effective way so that we then have the standing to go to other countries and start stitching back togeth¬er the nonproliferation treaties.” Then, on Sep¬tember 24, the president led the United Nations Security Council to approve a draft resolution that would step up efforts to rid the world of nu¬clear weapons. Our modeling results only strengthen the reasons to support further prog¬ress on such policy.
Source of Information : Scientific American January 2010
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