President-elect Barack Obama's nominee for energy secretary, Nobel Prize-winning physicist Steven Chu, said if confirmed he will pursue policies to address climate change and reduce U.S. dependence on foreign oil.  

At a hearing before the Senate Energy and Natural Resources Committee, Steven Chu said two key challenges facing the United States are climate change and making the nation more energy independent.

"Climate change is a growing and pressing problem.  It is now clear that if we continue on our current path, we run the risk of dramatic disruptive changes to our climate in the lifetimes of our children and our grandchildren.  At the same time, we face immediate threats to our economy, our national security that stem from our dependence on oil," he said.

Chu said the Obama administration would work to reduce greenhouse gas emissions that contribute to global warming through a cap-and-trade system.  As part of such a system power plants, oil refineries and industrial facilities that have high emissions would pay more than those that invest in technologies that curb emissions.

Chu, who currently serves as director of the Lawrence Berkeley National Laboratory in California, also underscored the importance of energy efficient technologies, biofuels and solar energy in reducing the U.S. dependence on foreign oil.

Some senators from states with oil and gas reserves urged Chu and the incoming Obama administration to encourage greater production of domestic resources.

Senator Lisa Murkowski is a Republican from Alaska.

"I feel very strongly that we have to enhance our domestic oil and gas production," she said.

Chu said domestic oil and gas production would be part of a comprehensive energy policy under the new administration.  But he said the United States has about four or five percent of the world's oil reserves, and that a more efficient use of energy would be a bigger factor in helping the nation decrease its dependency on foreign oil.

That brought a terse response from Senator Mary Landrieu, a Democrat from Louisiana, a state with offshore oil and gas reserves.

"I would urge you to be careful about the comment about four percent.  It is true we have four percent of the known reserves, but there is great evidence to suggest that there are a lot of reserves that are unknown," said Landrieu.

Despite the occasional pointed questioning, Chu is expected to be confirmed by the Senate as early as next week.

Chu, a former chairman of the physics department at Stanford University, shared the Nobel Prize for physics in 1997 for discovering a way to cool and trap atoms by using laser light.