Negotiators at a U.N. climate conference in Spain further defined plans for reducing greenhouse emissions and continued work on a draft climate change treaty, with next month's deadline for a legal document increasingly in doubt.

Swedish Prime Minister Fredrik Reinfeldt, whose country holds the European Union presidency, said the holdup in the U.S. Senate of a climate bill made it impossible to meet a deadline next month for adopting a binding agreement regulating the world's emissions of gases that cause global warming.

A flurry of diplomatic activity reflected high tensions worldwide as two years of negotiations approach a climax at a major climate conference opening Dec. 7 in Copenhagen.

But expectations of a deal have been eroding for months as the ongoing negotiations have bogged down in the minutia of a vastly complex agreement that would alter economies around the globe.

Though a full treaty appeared out of reach, U.N. and European leaders have said it was critical to sign on to an agreement containing the essential elements, with the details to be filled in later. But Reinfeldt indicated even that might not be attainable.

"It is often like that within political leadership, one promises to do something that one still hasn't got into place and that one might not even always have the complete technology or knowledge to get into place," Reinfeldt said in Stockholm after returning with other EU leaders from a summit in Washington with President Barack Obama.

At the talks in Spain, industrial countries responded to demands by African nations to spell out how they intended to meet announced targets for reducing carbon emissions.

Retreating behind closed doors, Australia and several European countries gave details of how much pollution they intended to cut and how they would meet the remainder of their emission targets by buying credits on a carbon market or by helping poor countries, for example, to build clean energy or avoid deforestation.

A study published this week in Nature Geoscience magazine suggested deforestation is responsible for fewer carbon emissions than generally accepted. The paper said the destruction and degradation of the world's forests accounted for 12 percent of human-induced emissions. A 2007 report by a Nobel Prize winning panel of U.N scientists put the figure at 20 percent. Like the U.N. panel, the scientists said their figure did not account for fires and the drainage of peatlands, which store heavy concentrations of carbon when wet.

The head of the 135-nation bloc of developing countries said that while industrial countries were clarifying their pledges, they were not increasing them as the Africans are demanding.

"I haven't seen any real serious indication that they are upping their ambitions," said Lumumba Di-Aping, of Sudan. "We will wait to see what happens." Continued...