"I think there will be expectations from countries to hear a new voice from the United States," said Jennifer Morgan, director of the climate and energy program at the World Resources Institute in Washington.
The climate officials and environment ministers meeting in the Qatari capital of Doha will not come up with an answer to the global temperature rise that is already melting Arctic sea ice and permafrost, raising and acidifying the seas, and shifting rainfall patterns with impacts on floods and droughts.
They will focus on side issues, like extending the Kyoto protocol — an expiring emissions pact with a dwindling number of members — and ramping up climate financing for poor nations.
They will also try to structure the talks for a new global climate deal that is supposed to be adopted in 2015, a process in which American leadership is considered crucial.
Many were disappointed that Obama didn’t put more emphasis on climate change during his first term. He took some steps to rein in emissions of heat-trapping gases, such as sharply increasing fuel efficiency standards for cars and trucks. But a climate bill that would have capped U.S. emissions stalled in the Senate.
"We need the U.S. to engage even more," European Union Climate Commissioner Connie Hedegaard told The Associated Press. "Because that can change the dynamic of the talks."
The world tried to move forward without the U.S. after the Bush Administration abandoned the Kyoto Protocol, a 1997 pact limiting greenhouse emissions from industrialized nations. As that agreement expires this year, the climate curves are still pointing in the wrong direction.
The concentration of heat-trapping gases like carbon dioxide has jumped 20 percent since 2000, primarily from the burning of fossil fuels like coal and oil, according to a U.N. report released this week. And each year, the gap between what researchers say must be done to reverse this trend, and what’s actually being done, gets wider.