Global Warming Unstoppable, Report Says

That amount of sea rise would take centuries, said Andrew Weaver of the University of Victoria in Canada, but "if you're in Florida or Louisiana, or much of western Europe or southeast Asia or Bangladesh ... or Manhattan ... you don't want that," he said.

The report spurred bleak reactions from world leaders.

"We are on the historic threshold of the irreversible," warned French President Jacques Chirac, who called for an economic and political "revolution" to save the planet.

"While climate changes run like a rabbit, world politics move like a snail: Either we accelerate or we risk a disaster," said Italy's environment minister, Alfonso Pecoraro Scanio.

And South Africa's Environmental Affairs Minister Marthinus van Schalkwyk said failure to act would be "indefensible."

In Washington, Bush administration officials praised the report but said they still oppose mandatory cuts in greenhouse gas emissions. The problem can be addressed by better technology that will cut emissions, promote energy conservation, and hasten development of non-fossil fuels, said Energy Secretary Samuel Bodman.

About three-fourths of Americans say they expect global warming will get worse, according to a recent AP-AOL News poll. However, other recent polls have found they don't consider it a top priority for the U.S. government.

But doing nothing about global warming could mean up to a 10-degree Fahrenheit temperature rise by the end of the century in the United States, said report co-author Jonathan Overpeck at the University of Arizona.

Elsewhere, the projected effects of global warming would vary on different parts of the globe.

Temperatures would spike higher near the poles, according to the report. Within 22 years _ whether greenhouse gases are controlled or not _ most of the Northern Hemisphere will see more high temperature extremes, the report showed. Places like Northern Africa will get even less rainfall.

This climate change "is just not something you can stop," said Trenberth. "We're just going to have to live with it. If you were to come up back in 100 years time, we'll have a different climate."

People experience the harshest effects of global warming through extreme weather _ heat waves, droughts, floods, and hurricanes _ said study co-author Philip Jones of Britain's University of East Anglia. Those have increased significantly in the past decade and will get even worse in the future, he said.