U.S. Energy Secretary Steven Chu and Commerce Secretary Gary Locke visit their ancestral homeland this week to press China to join with the United States in stepped-up efforts to fight global warming.

The two Chinese-American cabinet officials arrive in Beijing on Tuesday to talk with senior Chinese leaders and highlight how working together to cut greenhouse gas emissions would benefit both countries and the entire planet.

The trip also sets the stage for a visit by President Barack Obama to China later this year that many environmental experts hope will focus on the need for joint U.S.-China action before a meeting in Copenhagen in December to try to forge a global deal on reducing the emissions.

They believe cooperation, perhaps even a bilateral deal, between the world's largest developed country and the world's largest developing country is vital if efforts to forge a new global climate treaty are to succeed.

The potential is very large and the need is very serious, said Kenneth Lieberthal, a visiting fellow at the Brookings Institute, a U.S. think tank. It's not one of those things where one side benefits and the other side pays.

In recent years, China has surpassed the United States to become the world's biggest emitter of carbon dioxide and other heat-trapping gases blamed for global warming, although its per capita emissions are still far lower.

Chu, a Nobel physicist who has devoted years to climate change issues, is expected to make the case for U.S. and Chinese action to rein in rising global temperatures in a speech on Wednesday at Tsinghua University in Beijing.

We face an unprecedented threat to our very way of life from climate change, Chu told U.S. senators last week, warning the world could experience a climatic shift as profound as the last Ice Age but in the opposite direction.

Locke, a former governor from the export-oriented state of Washington, is eager to showcase opportunities for China to reduce carbon dioxide emissions using U.S. solar, wind, water and other renewable technology.

There's a huge need in China which creates huge market opportunities for our companies. At the same time, there are big challenges, a Commerce Department official said.


China relies on coal, the most carbon-intensive fuel, for over two-thirds of its energy needs and that dependence is expected to continue for decades to come.

The United States has the world's largest coal reserves and relies on coal for about 22 percent of its energy needs, creating a big incentive for the two countries to collaborate on technologies to capture carbon dioxide emissions and inject them far underground instead of into the air.

That's at the top of the list, David Sandalow, assistant energy secretary for policy and international affairs, told Reuters in a pre-trip interview. We believe we can do more working together than separately.

China's drive to build new nuclear power plants also has caught the attention of U.S. companies.

As Obama pushes Congress to complete work on a bill to reduce U.S. greenhouse gas emissions, he is under tremendous pressure to get China to agree to a quantitative emissions cap at December's meeting in Copenhagen.

Without such a commitment, a new climate change treaty is unlikely to pass the U.S. Senate, said Stuart Eizenstat, who was lead U.S. negotiator for the December 1997 Kyoto climate treaty, which was never ratified by the United States.

Although Chu and Locke are not going to Beijing for talks on a bilateral climate deal, the United States hopes closer cooperation with China will contribute to a favorable outcome in Copenhagen, Sandalow said.

China joined with 16 other major world economies last week in setting a goal of holding the global temperature rise to no more than 2 degrees Celsius from pre-industrial levels. But it has refused to set a short-term target for cutting emissions.

Beijing argues it has been industrializing for only a short time and that strict caps now would hamper growth and urbanization efforts in a country where most people live in much poorer conditions than in the West.

Still, the country's latest five-year plan set a goal of reducing energy intensity by 20 percent by the end of 2010. China has also set a target of using renewable energy to meet 15 percent of total demand by 2020.

The Obama administration should push Beijing to translate such goals into binding international commitments as a first step, Eizenstat said.

Eventually, China will have to agree to emission caps but that is unlikely this December in Copenhagen, he said.

(Editing by John O'Callaghan)