Study: Cuts in greenhouse gas could lessen warming

[April 15, 2009]  WASHINGTON (AP) -- A new scientific study finds that the absolute worst of global warming can still be avoided if the entire world cuts emission of greenhouse gases the way President Barack Obama and Europe want.

A computer simulation by the National Center for Atmospheric Research in Boulder, Colo., looked at what would happen by the end of the century if greenhouse gas levels were cut by 70 percent. The result: The world would still be a warmer world but by about 2 degrees instead of 4 degrees. Arctic sea ice would shrink but not disappear, and sea level would rise less.

About half the temperature increases and changes in droughts and floods can be avoided compared to a scenario without emission cuts, according to the study, which will be published next week in the journal Geophysical Research Letters. Future heat waves would be 55 percent less intense. Thawing of permafrost in the far north would also be reduced.

The study is one of the first to use computer models to quantify how much of the effects global warming can be avoided, compared to a world if nothing is done about the problem.

While the study looked at what would happen with dramatic cuts in future pollution, history has shown that reductions are much easier to talk about than to make. The controversial 1997 Kyoto Protocol called for industrialized countries to cut emissions but since then levels worldwide have gone up 25 percent. In the U.S., where emissions are up 6 percent in the last decade, Congress is fiercely arguing over a plan to reduce pollution.

"If we follow on the path that Obama has outlined of cutting emissions by 70 or 80 percent and the rest of the world does it, then we can make a big difference on the climate by the end of the century," climate scientist and study chief author Warren Washington told The Associated Press.

But if the United States and Europe cut back on carbon dioxide and China, India and other developing countries do not, then the world is heading toward a harsher hotter future, not the one the study shows, Washington said.

The study mapped areas that would benefit the most by emission cuts, comparing what would happen with less carbon dioxide pollution and what would happen if greenhouse gas continue to grow. The difference between the two scenarios is starkest for temperatures in Alaska and the mountain west, which would see temperatures rise a couple degrees less with emission cuts. Reduced carbon dioxide would also significantly lessen predicted future droughts on the Pacific coast and flooding in the Northeast.

Much of Europe, Russia, China and Australia would see the biggest temperature benefits from reductions in greenhouse gas pollution, while the Mediterranean, Caribbean and North Africa region would benefit the most in predicted changes in rainfall from less global warming.

If the world cuts back on fossil fuels, "it isn't going to be as bad," Washington said.

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On the Net:

The National Center for Atmospheric Research: http://www.ucar.edu/

[Associated Press; By SETH BORENSTEIN]

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