President-elect Barack Obama has named his top science advisors, and they are leading experts on global warming.

In his weekly radio address Obama named Harvard physicist John Holdren as Director of the White House Office of Science and Technology Policy.

He also tapped marine biologist Jane Lubchenco to lead the National Oceanic and Atmospheric Administration.

The selections signal a change from bush administration policies on global warming that were criticized for putting politics over science.

Obama says it is time to restore America's place as the world leader in science and technology.