Enlarge imageBy Alister Doyle, Environment Correspondent
PARIS (Reuters) - The U.N. climate panel agreed its strongest warning yet on Thursday that human activities are causing global warming that may bring more droughts, heatwaves and rising seas, delegates said.
The report, due for formal release on Friday and bolstering conclusions from a 2001 study, may put pressure on governments and companies to do more to curb greenhouse gases mainly from burning fossil fuels in power plants, factories and cars.
Scientists and government officials in the Intergovernmental Panel on Climate Change (IPCC), the most authoritative group on global warming, agreed it was "very likely" that human activities were the main cause of warming in the past 50 years, delegates said.
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In IPCC language, "very likely" means at least 90 percent probability and is the strongest link to human activities since the IPCC was set up in 1988. The previous study in 2001 said a link was "likely", or 66 percent probable.
"The phrase ’very likely’ was approved," said one delegate at the talks, who like others asked not to be named. IPCC officials declined comment, saying that the report would be released on Friday at 0830 GMT.
The IPCC, grouping 2,500 scientists from 130 countries, is also set to say that oceans will keep rising for more than 1,000 years even if governments stabilise greenhouse gas emissions.
The report is the first of four this year by the panel that will outline threats of warming.
The Paris study, looking at the science of global warming, will also project a "best estimate" that temperatures will rise by 3 Celsius (5.4 Fahrenheit) by 2100 over pre-industrial levels, the biggest change in a century for thousands of years.
MORE RAIN, LESS ICE
It says bigger gains, of up to 6.3C in one model, cannot be ruled out but do not fit well with other data. The world is now about 5C warmer than during the last Ice Age.
The draft projects that Arctic ice will shrink, and perhaps disappear in summers by 2100, while heatwaves 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 (11-17 inches) 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.
Rahmstorf wrote a report last year saying that observations of past changes indicated a bigger rise by 2100, of 50-140 cm.
The Eiffel Tower in Paris, near where the IPCC experts were meeting, was to shut off its famous night-time illuminations for five minutes on Thursday night to draw attention to energy use.
U.N. 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 U.N.’s Kyoto Protocol and want outsiders such as the United States, China and India to do more.
Last week 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.
