OSLO The United States has a chance to regain lost leadership in fighting climate change under President-elect Barack Obama that would add pressure on countries such as China to do more, experts say.
Yet world economic gloom will make it hard to work out a new U.N. climate treaty by a planned deadline of the end of 2009, even with a more enthusiastic president than George W. Bush.
Many foreign experts hailed Obama's plan to cap greenhouse gas emissions as a welcome shift from Bush, who kept the United States isolated from 37 other industrial nations by rejecting the U.N.'s carbon-capping Kyoto Protocol.
"The world's leading economy...has moved from being a brake on progressive policy-making to potentially becoming a locomotive," said Achim Steiner, head of the U.N. Environment Program.
Steiner and other green experts welcomed Obama's victory speech that defined top challenges as "two wars, a planet in peril, the worst financial crisis in a century."
By contrast, Bush did not mention "climate change" in a farewell speech to the United Nations in September.
He views Kyoto as too costly and said it wrongly omitted goals for poor nations such as China and India. The United States effectively ditched Kyoto in 1997 when the Senate voted 95-0 against its key principles under President Bill Clinton.
Obama will quickly have to move beyond just words, but foreign experts said the change in rhetoric may help. Poor nations have taken a lack of strong climate action by the United States, the world's richest economy, as an excuse to wait.
"An Obama victory puts more pressure on China...because if the United States becomes more active, that will lift expectations on China as well," said Guan Qingyou, a climate policy researcher at Tsinghua University in Beijing.
China and the United States are the top emitters, but U.S. emissions per citizen are four times those of China.
Obama may not have time to work out details of U.S. climate policies before the end of 2009, when 190 nations plan to agree a new climate deal in Copenhagen. In the worst case, the talks could end in stalemate, or spill into 2010.
Obama "has a lot to do in a very short time," said Connie Hedegaard, Denmark's Climate Change Minister, who will host talks on the new climate treaty to succeed Kyoto. Rich nations are meant to set new greenhouse gas cuts, perhaps for 2020.
"I wish I knew the answer to that question," Yvo de Boer, head of the U.N. Climate Change Secretariat, said when asked if the United States would be ready to outline cuts in Copenhagen.
"The U.S. election outcome could provide new momentum to the climate negotiations. But we should remain realistic," South African Environment Minister Marthinus van Schalkwyk said. Obama's plans were "not as ambitious as we would like to see."
De Boer said he was "very encouraged" by Obama's stated policies and said he hoped the president-elect, or a top adviser, would visit the next round of U.N. climate negotiations in Poznan, Poland, on December 1-12.
He said he was less pessimistic than before that economic downturn would distract from fighting global warming. Big new investments to create "green jobs," for instance in renewable energies such as solar or wind power, could solve both.
"I originally had the fear that the financial crisis would be devastating to the negotiating process," he said.
ECONOMY, HEALTH, IRAQ
Opinion polls have shown Americans want Obama to focus on the economy, health care and the Iraq war. Energy, including renewables, comes far down the spending wish list.
The U.N. Climate Panel says it will cost up to 0.12 percent of global gross domestic product every year to 2050 to avert the worst of global warming, blamed mainly on burning fossil fuels. It predicts droughts, disease, heatwaves and rising seas.
Obama aims to cut U.S. emissions by 80 percent below 1990 levels by 2050, but Copenhagen is about shorter-term cuts. He plans investments in a clean energy economy of up to $150 billion over 10 years and foresees 5 million new green jobs.
A possible spanner for Copenhagen is that developed nations, including the United States, have promised "comparable" efforts.
The European Union plans cuts of 20 percent below 1990 levels by 2020. But U.S. emissions were 14 percent above 1990 levels in 2006 -- to match EU cuts, Obama would have to axe by an economy-throttling 30 percent by 2020 from 2006.
(With extra reporting by David Fogarty in Singapore, Karin Jensen in Copenhagen and Chris Buckley in Beijing)
(Editing by Philippa Fletcher)