The United States and China should hold a summit featuring an agreement on climate change, helping to create international support for a new global pact by the end of 2009, a former White House adviser said on Thursday.

China and the United States have often been icy rivals over trade and security, and they are also the world's top two emitters of the greenhouse gases from burning fossil fuels that are stoking global warming.

Kenneth Lieberthal, a former National Security Council officer on Asia in the Clinton administration and now at the Brookings Institution in Washington, D.C., said the two powers should make fighting global warming a centerpiece under President Barack Obama.

A summit between Obama and Chinese President Hu Jintao featuring clean energy and curtailing greenhouse gases as one of the major issues would help surmount domestic misgivings in each country and lift hopes for agreeing a successor to the current Kyoto Protocol by the end of 2009, Lieberthal said in Beijing.

Kyoto is the United Nations' main weapon to fight climate change.

We should use Sino-U.S. cooperation in order to create momentum for other countries' efforts, which will in turn increase the chances for success at the global climate negotiations, he said.

He was speaking at the release of a study by him and another former Clinton official, David Sandalow, advocating China-U.S. cooperation on climate change. The study is available on the Brookings website (www.brookings.edu).

Lieberthal's call came a week after Secretary of State Hillary Clinton's visit to Beijing, when she pushed the issue.

GULF

He said he did not know whether his call for a summit would be adopted. But he was encouraged by the actions of the Obama administration and saw some chance of the two leaders meeting in a summit later in the year before global climate change negotiations culminate in Copenhagen.

I do believe that both leaderships see a very significant value in meeting together personally, said Lieberthal.

But despite the upbeat talk, a gulf still divides Washington and Beijing on many practical issues.

Chinese officials have said their country is now probably the world's biggest emitter of carbon dioxide, the main greenhouse gas from vehicles, factories, farms and land clearance. Most experts say it has clearly passed the United States, long the top emitter.

But Beijing has refused to consider caps on its greenhouse gas output, noting that the nation's average per-capita emissions are much lower than the West's.

China also points out that, historically, much of the carbon pollution in the atmosphere is from rich industrialized nations.

The Bush administration cited China's refusal to accept emissions caps as one reason for its refusal to ratify the Kyoto Protocol, whose current phase expires at the end of 2012.

Lieberthal said a bilateral agreement and then clearer emissions undertakings from China would help overcome any opposition in Congress to the United States joining a successor to Kyoto.

Chinese leaders have to understand that they effect President Obama's ability to get climate change legislation completed, he said.

(Reporting by Chris Buckley; Editing by David Fogarty)