Barack Obama ushered in a revolution in America's response to global warming yesterday when he appointed one of the world's leading climate change experts as his administration's chief scientist.

The president-elect's decision to make Harvard physicist John Holdren director of the White House Office of Science and Technology Policy reveals a new determination to draw a line under eight years of US policy that have seen George Bush steadfastly reject overwhelming evidence of climate change.

News of the appointment was hailed by scientists around the world, including former UK chief government scientific adviser Sir David King. "This is a superb appointment," he told the Observer. "Holdren is a top-rate scientist and his position on climate change is as clear as you could get. This is a signal from Barack Obama that he means business when it comes to dealing with global warming."

Obama also used his weekend radio address to announce that respected climatologist Jane Lubchenco is to head the National Oceanic and Atmospheric Administration. The appointments follow Obama's selection of Steven Chu, a Nobel prizewinner, to the Department of Energy, where he has been directed to lead the development of alternative energy sources.

"Today, more than ever before, science holds the key to our survival as a planet and our security and prosperity as a nation," Obama announced. "It's time we once again put science at the top of our agenda and ... worked to restore America's place as the world leader in science and technology."

In one telling remark, he added that respect for the scientific process was not "just about providing investment and resources. It's about ensuring that facts and evidence are never twisted nor obscured by politics nor ideology."

Obama's appointments are outspoken proponents of the need for urgent action over climate change, and they come after eight years of inaction, during which the Bush administration resisted international emission-reduction accords and the introduction of US laws to protect threatened species.

Holdren, whose expertise runs from nuclear-weapons proliferation to global warming, recently warned in a speech at Harvard that he considered "global warming" to be a misnomer. "It implies something gradual, something uniform, something quite possibly benign, and what we're experiencing is none of those. There is already widespread harm ... occurring from climate change. This is not just a problem for our children and our grandchildren."

As he pointed out, new figures point to a rapid acceleration in the loss of Arctic sea ice, as well as dramatic acidification of the ocean.

With the international community looking to America for leadership, Obama has made it clear that, despite the global economic crisis, the success of his presidency will hinge on a revolution in America's use and production of carbon-based energy. The selection of marine expert Lubchenco underscores that. She has warned that even if the world abruptly shifts away from fossil fuels, the oceans will continue to soak up carbon dioxide and become more acidic. She recommends protecting marine life by reducing overfishing, cutting back on nutrient run-off and creating marine reserves to protect marine eco-systems.

"The Bush administration has not been respectful of the science," she said earlier this year. "I am very much looking forward to a new administration that does respect scientific information and considers it very seriously in making environmental policies."

In another signal of his determination to move on the environment, Obama appointed Carol M Browner as his climate tsar last week. She was quoted as saying: "Time and time again, when the nation has set a new environmental standard, the naysayers have warned it will cost too much. But, once we have set those standards, American ingenuity and innovation have found a solution at a far lower cost than predicted."

For Obama, the creation of this green team is part of a broader push toward economic and environmental self-enlightenment. He has expressed hope that engaging technology with environmental and energy policy will lead to significant job creation.