Forty leaders plan to attend climate talks: U.N.

The meeting exposed a deep rich-poor divide about sharing out the burden of curbs on greenhouse gas emissions meant as part of a worldwide assault to avert droughts, wildfires, extinctions and rising seas.

"Developed countries are acting as a brake toward any meaningful progress" said Lumumba Stanislaus Di-Aping of Sudan, chair of the Group of 77 and China, representing poor nations. African nations boycotted some talks Tuesday in protest.

"We do not have the option of delay," said Dessima Williams of Grenada, representing small island states which say they risk being swamped by rising sea levels. She said a Copenhagen deal had to be legally binding and rejected talk of a delay.

De Boer said Copenhagen "can and must be the turning point in the international fight against climate change" but said time was too short to seal a full legal treaty in 2009.

He said Copenhagen should at least set 2020 greenhouse gas emissions goals for all rich nations, agree actions by the poor to slow their rising emissions and agree ways to raise billions in funding and mechanisms to oversee funds.

"I believe that the U.S. can commit to a number in Copenhagen," de Boer said.

A U.S. climate change bill cleared its first hurdle in the U.S. Senate Thursday, but Democrats are likely to fall far short of their goal of passing legislation in the full Senate before Copenhagen.

That would make it difficult for the United States, the number two emitter after China, to offer an internationally binding emissions reduction target in Copenhagen. That in turn makes it hard for other nations to make commitments.

"That's a decision yet to be made," Jonathan Pershing, head of the U.S. delegation, said when asked if Obama would give a number before the Senate agreed legislation.