Speaking at the start of a four-day scientific conference in Reykjavik, Corell said global warming was melting the Greenland ice sheet and Arctic glaciers from Alaska to Norway quicker than previously thought.

"Greenland will play a much bigger role in sea level rise than anticipated," said Corell, a scientist at the American Meteorological Society.

He said a 2001 U.N. report forecast world ocean levels would rise by 20-90 cms by 2100. He said some U.N. forecasts assumed melting Greenland ice would cause just 4 mm of the rise.

"We'll be at the top of the range, about a meter," he said. The ACIA report says that Greenland's melt alone could add 10 cms to global sea levels by 2100. Melting of other Arctic glaciers would also contribute.

About 17 million people in Bangladesh live less than one meter above sea level. Pacific islands like Tuvalu could be swamped and much of Florida south of Miami would be inundated by a one meter rise.

TWICE GLOBAL AVERAGE

Much of the rise projected by U.N. surveys in the years to 2100 is because water in the oceans expands as it warms, and so is not directly connected to melting ice.

At the other end of the globe from the Arctic, the thicker Antarctic ice is expected to stay more stable, like a deep freeze

The ACIA report was funded by Arctic nations the United States, Canada, Russia, Iceland, Norway, Sweden, Denmark and Finland and is the biggest survey to date of the Arctic climate, by 250 scientists.

It says Arctic temperatures are rising by twice the global average and are set to rise by a further 4-7 Celsius (7-13 Fahrenheit) by 2100.

The report says the melt will threaten the cultures of indigenous peoples and could drive species like polar bears toward extinction as sea ice recedes.

The Arctic heats more rapidly than the global average because dark water, earth and rock, once exposed, soak up more heat than reflective snow and ice.

The eight Arctic governments are due to meet in Iceland on Nov. 24 to decide what to do. Diplomats say they are deadlocked, with Washington the most strongly opposed to radical action.

"There are mixed signals in the United States," Corell said of Washington's attitude toward tackling global warming. But "I think that there is a shift going on."

He said that some Republican senators, for instance, had asked him for personal briefings about the climate report.

Senator John McCain, a Republican who has cooperated with Democrats on global warming, is optimistic about passing a bill in coming years to cap U.S. greenhouse gas emissions, he said.

President Bush pulled out in 2001 of the U.N.'s Kyoto protocol, a first step toward limiting emissions of gases like carbon dioxide from fossil fuels in cars, factories and power plants. Bush argues that Kyoto was too costly and wrongly excluded developing nations.