WASHINGTON - President-elect Barack Obama yesterday named a Harvard physicist and a marine biologist to science posts, signaling a change from Bush administration policies on global warming that were criticized for putting politics over science.

Both John Holdren and Jane Lubchenco are leading experts on climate change who have advocated forceful government response. Holdren will become Obama's science adviser as director of the White House Office of Science and Technology Policy; Lubchenco will lead the National Oceanic and Atmospheric Administration, which oversees ocean and atmospheric studies and does much of the government's research on global warming.

Holdren also will direct the president's Council of Advisers on Science and Technology. Joining him as cochairs will be Nobel Prize-winning scientist Harold Varmus, a former director of the National Institutes of Health, and Massachusetts Institute of Technology professor Eric Lander, a specialist in human genome research.

"From landing on the moon to sequencing the human genome to inventing the Internet, America has been the first to cross that new frontier because we had leaders who paved the way," Obama said in announcing his selections in his weekly radio address. "Leaders who not only invested in our scientists, but who respected the integrity of the scientific process."

"Because the truth is that promoting science isn't just about providing resources - it's about protecting free and open inquiry. It's about ensuring that facts and evidence are never twisted or obscured by politics or ideology," he said. "I could not have a better team to guide me in this work."

In their posts, the four scientists will confront challenges in global warming after years of inaction by the Bush administration, which opposed mandatory cuts of greenhouse-gas pollution. Last year, former Surgeon General Richard Carmona testified to Congress that top Bush administration officials often dismissed global warming as a "liberal cause" and sought to play down health reports out of political considerations.

Since 1993, summer Arctic sea ice has lost the equivalent of Alaska, California and Texas, and global warming is accelerating. The amount of carbon dioxide in Earth's atmosphere has already pushed past the level some scientists say is safe.

Holdren is a former president of the American Association for the Advancement of Science in Washington who has pushed for more urgent action on global warming. As Obama's top science adviser, he would manage about 40 Ph.D-level experts who help shape and communicate science and technology policy.

Lubchenco, an Oregon State University professor specializing in overfishing and climate change, will be the first woman to head NOAA. A member of the Pew Oceans Commission, Lubchenco has recommended steps to overcome crippling damage to oceans from overfishing and pollution.

Varmus, who was a co-recipient of the Nobel Prize for his research on the causes of cancer, served as National Institutes of Health director during the Clinton administration.

Lander, who teaches at MIT and Harvard, founded the Whitehead Institute-MIT Center for Genome Research in 1990, which became part of the Broad Institute in 2003.