WASHINGTON (AFP) – The US pointman on climate change voiced optimism Monday at reaching a new global treaty this year, saying that top polluters China and the United States were both serious about taking action.

The top developed and developing economies discussed global warming among a host of issues as they held top-level talks in Washington.

The talks come as the clock ticks to a December conference in Copenhagen, which is meant to seal a new international accord on fighting climate change after the Kyoto Protocol's requirements expire in 2012.

"I'm not going to kid anybody -- I don't think it's easy -- but I think that we will get there," Todd Stern, the US special envoy on climate change, told reporters on a conference call after the first of two days of talks here.

"I think there's a lot of interest on the Chinese side fundamentally to arrive at a constructive and successful outcome in Copenhagen," Stern said.

Stern said that President Barack Obama's administration has made it clear to China that global warming was a top priority, with Secretary of State Hillary Clinton and other officials raising the issue at all opportunities.

China sees global warming as important "as a substantive matter, but also of real importance in the US-China bilateral relationship and increasingly something that's going to be important on its own for the way they are perceived by the rest of the world," Stern said.

But Stern acknowledged that China, India and other developing nations still had different views than rich countries on climate change.

Developing nations have resisted pressure to commit to binding targets on cutting carbon emissions blamed for global warming, saying that rich nations bear historic responsibility.

The US House of Representatives, led by Obama's Democratic Party, last month narrowly approved a plan to restrict emissions. It marked a sharp turn from the era of Obama's predecessor George W. Bush, a sharp critic of international action on climate change.

Obama, inaugurating the talks with China, said that the two nations can "chart a low carbon recovery" from the global financial crisis.

"Let's be frank: neither of us profits from a growing dependence on foreign oil, nor can we spare our people from the ravages of climate change unless we cooperate," Obama told the opening session.

"Common sense calls upon us to act," he said.