Scientists from 30 nations as varied as Australia, India and Japan will meet in Exeter, England, from Feb. 1-3 to try to define what constitutes "dangerous" levels of warming. But they will not make any recommendations to policymakers.

"The purpose is to have a debate of the scientific facts. We will collect the best information we have to give to the politicians ... but don't expect to make any recommendations," conference chairman Dennis Tirpak said ahead of the meeting.

It is far short of the fanfare with which British Prime Minister Tony Blair announced the conference last September, promising an agenda-setting meeting for his presidency of the Group of Eight (G8) rich nations.

The Kyoto protocol, the UN plan for reining in emissions of greenhouse gases from cars, factories and power plants, will enter into force on Feb. 16 with backing from almost all rich nations except the United States.

President George W. Bush pulled out in 2001, arguing Kyoto was too costly and wrongly excluded poor nations.

Last week a panel of experts, the International Climate Change Taskforce, urged Washington to join other nations in a drive to avert the "ecological time bomb" of global warming.

On Sunday the WWF environmental group warned that catastrophic climate change could kick in within 20 years unless greenhouse gas emissions are cut sharply.

It said entire species such as polar bears could be pushed towards extinction this century as a result.

PURE SCIENCE

Blair's former environment minister Michael Meacher, a regular critic of the government on green issues, regretted the lack of recommendations.

"It is a bit of a weakness. They should draw it all together and present the politicians with best and worst case scenarios -- pointing out that even under the best case there are some pretty dire consequences. That leaves no wriggle room," he said.

Blair returned to the attack in a speech last week at the World Economic Forum in Switzerland.

"It may be true to say that the evidence is still disputed. It would be wrong to say that the evidence of danger is not clearly and persuasively advocated by a very large number of entirely independent and compelling voices," he said.

"We must send a clear message that ... we are united in moving in the direction of greenhouse gas reductions. This isn't an issue that is going away."

Washington has rejected caps on emissions set by Kyoto.

Some scientists have said two degrees centigrade of warming is already expected -- with a major contributor being human activities like burning fossil fuels to generate electricity which produces vast quantities of heat-trapping carbon dioxide.

They have also warned that above two degrees the warming might start pushing the planet into the unknown as ice caps melt, sea levels rise and weather patterns change at accelerating rates, putting millions of people at risk.