BEIJING — The head of the U.N.'s climate change body said today that he hopes the United States will take a more active role in fighting global warming once Barack Obama becomes president.

"With President-elect Obama, my hope is that the U.S. can take on a leadership role and help to move the negotiations forward," said Yvo de Boer, executive director of the United Nations Framework Convention on Climate Change.

DeBoer spoke in a news conference at a U.N.-sponsored climate change conference in China's capital. The two-day meeting will discuss technology transfers between nations and comes before a U.N. conference set for early December in Poland, where countries will begin negotiations for a climate change accord to succeed the 1997 Kyoto Protocol, which expires in 2012.

The United States rejected the Kyoto accord, arguing it would harm American business and made no comparable demands on emerging economies. China, India and other large developing countries signed the accord but refused to accept a binding agreement that they said would limit their development and their ability to ease poverty at home.

Obama has said he wants to make the U.S. a leader on climate change and re-engage with the U.N. Framework Convention on Climate Change, the parent treaty of the Kyoto accord. He said he plans to introduce emissions caps to the U.S., and reduce greenhouse gas emissions by 80 percent by 2050.

But even under an Obama administration, the U.S. is not likely to join the Kyoto Protocol, said de Boer. Emissions of greenhouse gases in the U.S. have risen about 14 percent since 1990 levels, he said, whereas they would have had to decline by 6 percent if the nation was part of Kyoto.

De Boer said he hopes practical proposals will emerge from the Beijing conference on how to develop resources for development and transfer of technology to developing countries, including setting up public private partnerships for high-level technology that companies wouldn't invest in alone.

"If international technology transfers happens, the developing countries like China will be able to take action that is not affordable to them at the moment," de Boer said.

In a speech to open the conference, Chinese Premier Wen Jiabao repeated China's long-standing belief that rich countries should take the lead in addressing climate change.

"It took developed countries several decades to solve the problems of saving energy and cutting emissions, while China has to solve the same problem in a relatively much shorter period. So the difficulty is unprecedented," Wen said.

According to some experts, China has surpassed the United States to become the world's biggest emitter of carbon dioxide, a greenhouse gas whose emissions contribute to global warming. Most of China's greenhouse gases come from coal combustion, but the country is reluctant to commit to a cut in emissions because its booming economy is dependent on coal for its energy needs.