Environmentalists denounced the new Canadian proposal as too vague to slow mounting signs of climate change. The WWF group said 2005 was set to be the warmest year on record, marked by hurricanes and a shrinking of Arctic ice to a record summer low.

Under Canada's proposal, the UN meeting of almost 10,000 delegates should agree "to engage in discussions to explore and analyse long-term cooperative action to address climate change."

The proposed discussions, lasting until December 2007, would involve all 189 nations in the UN's 1992 climate convention, including the United States and big developing nations such as China and India, it said.

The United States, a source of a quarter of all greenhouse gases, has repeatedly said it is not interested in UN-led talks on the long-term, seeing them as a prelude to caps on emissions like under the UN's Kyoto Protocol. Washington opposes Kyoto.

Most scientists say that a build-up of heat-trapping gases from fossil fuels burnt in power plants, factories and cars is already warming the planet and could herald catastrophic changes such as a rise in sea levels spurred by melting icecaps.

FLOOD OF SCIENCE

Bill Hare, climate director of environmental group Greenpeace said the Canadian proposal was "anodyne, almost meaningless" and accused Ottawa of lowering ambitions too far in a vain drive to enlist Washington.

"The scientific community is flooding us with results showing global changes," he said. "The scientific urgency is not being matched by these talks." Ministers from more than 90 nations will join the Montreal meeting from Wednesday.

And insurer Munich Re said that 2005 would be the costliest on record in terms of weather-related disasters such as Hurricane Katrina. Economic losses will be over $200 billion and insured losses would exceed $70 billion, it said.

Environmentalists urged about 40 industrial nations who are part of the Kyoto Protocol, binding them to cut greenhouse gas emissions by 5.2 percent below 1990 levels by 2008-12, to forget Washington and instead focus on plans for new cuts beyond 2012.

President George W. Bush pulled out of Kyoto in 2001, saying it would cost jobs and wrongly excluded developing nations from the first set of targets. Washington is not a party to discussions on Kyoto's future in Montreal.

Some US senators and mayors predicted that Washington would eventually sign up for curbs on emissions.

"It is inevitable that after the cities and states show it is safe, the politicians in Washington D.C. will join and again the United States will take its moral responsibility," said Seattle Mayor Greg Nickels, who favors emissions cuts.

The Canadian proposal for discussions would seek to promote development for the poorest nations, help countries adapt to climate change, foster new technologies such as wind or solar power and help realise "the full potential of markets."

And Arctic indigenous peoples, saying an accelerating thaw could spell disaster for their hunts of animals like seals or whales, urged the conference to help protect them from warming.