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Politics : PRESIDENT GEORGE W. BUSH -- Ignore unavailable to you. Want to Upgrade?

To: Thomas A Watson who wrote (162981)	7/20/2001 10:35:32 PM
From: puborectalis	Read Replies (3) \| Respond to of 769670

Scientists compute odds of warming By Seth Borenstein Knight Ridder Newspapers WASHINGTON — The odds are dead even that the world's average temperature will increase at least 5 degrees by the end of the century, enough to trigger flooding, famine and drought across much of the globe, according to a new study in today's edition of the journal Science. It's the first time scientists have computed the likelihood that Earth would get warmer by specific degrees. The study addresses a key criticism about the issue of global warming, that of scientific uncertainty, which the Bush administration has cited for its go-slow approach to the issue. The study was done by Tom Wigley, a senior scientist at the U.S. National Center for Atmospheric Research in Boulder, Colo., and Sarah Raper of the University of East Anglia in England. Their findings were published as world leaders meet in Germany to work on the controversial 1997 Kyoto treaty to fight global warming. Their study concluded that there is a 90 percent chance global warming will increase Earth's temperature from 3 to 9 degrees by 2100. Wigley and Raper consider a 5-degree increase most likely. There is a 50-50 chance that the world will get at least one degree warmer by 2030. Scientists are beginning to use these probability studies, which mathematically set the odds for an event, to try to understand what global warming might mean in the decades ahead. A probability study "gives you a better feel for how much you have to worry and how much risk there is in not doing anything," said Peter Stone, a climate scientist at the Massachusetts Institute of Technology, who this week released a similar probability study. When it comes to global warming, Stone said, "There is a substantial risk that there will be important big changes." The 5-degree increase by 2100 crosses a key threshold for climate scientists. That would make it hot enough to cause more tropical diseases, droughts, floods, heat waves, and severe weather in general — potentially killing or displacing hundreds of millions of people, according to a February report by a United Nations-sponsored committee of the Intergovernmental Panel on Climate Change. Effects for the United States would be milder than for countries that already have tropical or semi-tropical climates. A federal study last year found the United States could produce more food overall if temperatures were 5 degrees higher. But there would be more severe droughts and flooding, plus inundation of beaches, islands and marshes. The estimate of relatively fast-rising temperatures is within the range predicted by the U.N. panel. The U.N. panel of hundreds of international scientists concluded Earth's average temperature was likely to rise between 2.5 and 10.4 degrees Fahrenheit in the coming century, up significantly from the panel's 1995 estimate of 1.4 degrees. The U.N. panel did not put a probability on its numbers. The vast majority of climate scientists agree that world warming is spurred by carbon dioxide and other greenhouse gases from the burning of fossil fuels. The gases trap heat in the atmosphere. There are, however, detractors. The study by Wigley and Raper entailed more than 110,000 computations of five key variables. They were: how much carbon dioxide is emitted, how sensitive the climate is to carbon dioxide, how much heat the world's oceans can absorb, uncertainties in the way carbon dioxide builds up, and the cooling effects of other pollutants. The MIT climate scientists, using slightly different assumptions, came up with a 50-50 probability that the temperature will rise by at least 4 degrees, not 5. Another MIT climate scientist, Richard Lindzen, a critic of global warming science who did not participate the studies, said probability estimates are skewed by biases in what goes into the computer. Other critics argue that warming is a natural cycle and man-made causes play an insignificant role.