The Paris study, looking at the science of global warming, will also project a “best estimate” that temperatures will rise by 3 C by 2100 over pre-industrial levels, the biggest change in a century for thousands of years. It says bigger gains, of up to 6.3 C in one model, cannot be ruled out but do not fit well with other data. The world is now about 5 C warmer than during the last Ice Age.

The draft projects that Arctic ice will shrink, and perhaps disappear in summers by 2100, while heat waves and downpours would get more frequent. The numbers of tropical hurricanes and typhoons might decrease but the storms would become stronger. The Gulf Stream bringing warm waters to the North Atlantic could slow, although a shutdown is highly unlikely, it says.

And sea levels are likely to rise by between 28 and 43 cm this century, a lower range than forecast in 2001. Rising seas threaten low-lying Pacific islands and low-lying coastal nations from Bangladesh to the Netherlands. “Governments planning coastal defences have to live with large uncertainties for now, and quite some time in future,” said Stefan Rahmstorf of Germany’s Potsdam Institute for Climate Impact Research.

UN officials hope the IPCC report will spur stalled talks on expanding the fight against global warming. Thirty-five industrial nations aim to cut emissions of greenhouse gases to five percent below 1990 levels by 2008-12 under the UN’s Kyoto Protocol and want outsiders such as the United States, China and India to do more. Last week US President George W. Bush said climate change was a “serious challenge”. But he has stopped short of capping emissions despite pressure from Democrats who control both houses of Congress — arguing Kyoto would damage the economy.

... contd.