Report on Warming Offers New Details

Estimates Specify Effects on Different Regions of U.S.

Man-made climate change could bring parching droughts to the Southwest and pounding rainstorms to Washington, put Vermont maple sugar farms out of business and Key West underwater over the next century, according to a federal report released yesterday.

The report, a compilation of work by government scientific agencies, provided the most detailed picture yet of the United States in 2100 -- if nothing is done to cut greenhouse gas emissions.

It found that a warmer world, with average U.S. temperatures increasing four to 11 degrees, would significantly alter natural ecosystems and urban life. More than before, scientists broke down those effects to the regional level.

The timing of yesterday's report was also significant, with the House of Representatives considering a bill that would cap heat-trapping emissions.

"In our back yards, climate change is happening, and it's happening now," Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration, said at a news conference yesterday afternoon. She continued: "It's not too late to act. Decisions made now will determine whether we get big changes or small ones."

The report, available online at http://www.globalchange.gov, began by restating what other scientific panels have said: Warming of the climate is "unequivocal," and man-made greenhouse gases are primarily to blame.

Among the specific effects it found for the United States:

-- The heaviest rainstorms have already become 67 percent heavier since 1958 in the Northeast, as warmer weather evaporates more water vapor into the atmosphere to feed storm clouds. Around the Great Lakes, "lake effect" snowstorms could get heavier as ice recedes and exposes more open water.

-- The hottest days could get hotter across much of the country: Parts of the South that experience about 60 days a year with temperatures higher than 90 degrees could experience 150 such days by 2100. The same warming could make Washington's summers even more uncomfortable.

-- Higher temperatures could mean longer growing seasons for some farmers but might also bring more pests or change weather patterns that some crops depend on. Scientists said a warmer New England would be less hospitable to maple sugar farms, apple orchards and cranberry bogs.

-- Sea levels might rise three feet this century, which could flood a large section of South Florida.

That last prediction has brought worries even to a famously carefree place: Margaritaville, the restaurant-shop complex in Key West founded by singer Jimmy Buffett.

"It's going to affect us now, if the word gets out enough," said Martin Lehmann, working in the office there yesterday, thinking of employees who live on the low-lying island. "Our already declining house prices will go down even further."

But Paul Schlegel of the American Farm Bureau said news of the study had not changed his organization's unhappiness with the House bill. Schlegel said the effects of climate change are still just a forecast, while he believes it is a certainty that the bill would add crippling costs to farmers.