Barack Obama yesterday promised to end George Bush's "twisting" of science to suit "politics or ideology" in an extraordinarily outspoken address to the nation, and announced that he was putting top climate scientists in key positions in his administration.

The move, which signals perhaps his sharpest break with the outgoing administration, makes it clear that he was going to put climate change and the environment among the most urgent priorities of his presidency.

And as if to emphasise the difference, President Bush is using his last weeks of power to push through a record number of last-minute rule changes to increase mining and oil drilling on public lands, and even to allow people to carry concealed, loaded guns into national parks.

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During its years in office the Bush administration attempted to muzzle senior government scientists who disagreed with it, and even altered scientific reports – causing more than 60 top academics to sign a petition accusing the White House of manipulating findings for political reasons.

But in his weekly radio address, Mr Obama pointedly promised to end this. "Promoting science is about free and open inquiry," he said. "It's about ensuring that facts and evidence are never twisted or obscured by politics or ideology. It's about listening to what our scientists have to say, even when it's inconvenient – especially when it's inconvenient. That will be my goal as president of the United States."

The president-elect used the address to announce his top scientific appointments, which included two of the world's most respected climate scientists, John Holdren and Jane Lubchenco, in a move warmly welcomed even by the country's top Republican environmentalist. They will have enormous influence over his government's green policies.

The appointments follow the naming earlier this month of Steven Chu – a Nobel prize-winning physicist, and another prominent advocate of urgent measures to tackle climate change – to the key position of energy secretary, and a decision to create a special office on energy and climate within the White House headed by Carole Browner, Bill Clinton's former environment chief.

Both Professors Holdren and Lubchenco are past presidents of the American Association for the Advancement of Science. Professor Holdren, a professor at Harvard University and director of the blue-chip Woods Hole Research Center, will be science adviser to Mr Obama, who has elevated the position to an official assistant to the president.

He recently called for immediate action on climate change, saying that it was already causing "widespread harm". But he is also sceptical about nuclear power, reflecting a feeling in the Obama team that it cannot be made economical.

Professor Lubchenco, of Oregon State University, a similarly outspoken expert on oceans and global warming, is to be the first female administrator of the National Oceanic and Atmospheric Administration, which measures the pace of global warming, tracks hurricanes and monitors the health of the world's seas.

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The chief scientist at Defra, Professor Bob Watson, who worked in the Clinton White House, said yesterday that Obama was putting together "a phenomenal team of world- class scientists", as a sign that he was "totally committed to the environment".

William K Reilly – President George Bush's environment chief and the country's leading Republican environmentalist – told The Independent on Sunday that he was "very pleased" by the appointments of "long-standing advocates of addressing climate change".

In another clear indication that the incoming team has taken on board the arguments of those advocating a "green new deal" that expanding environmental industries and jobs is the best way out of the recession, Mr Obama on Friday signed up a vocal advocate of green jobs, Hilda Solis, to be his labour secretary. The Californian congresswoman will be a key figure in implementing a plan to create millions of green jobs.

US environmentalists, however, are split over yet another appointment – of Colorado senator Ken Salazar – as secretary of the interior. It was welcomed by the top environmental pressure groups, but smaller and more radical ones said he had had a mixed record in congressional votes. "He's far from the most anti-environmental guy out there," says Kieran Suckling of the Center for Biological Diversity, "but he's no environmental hero."

Meanwhile, Mr Bush has been pushing through a record number of so-called "midnight regulations". He has enabled coal-mining firms to dump waste in valleys, relaxed pollution rules from factory farms, and allowed companies that produce toxic wastes to burn them as fuel.

Barack's green team

Professor Steven Chu The Nobel Prize-winning physicist becomes Energy Secretary. He is a forceful advocate of America's urgent move towards carbon-free energy.

Professor John Holdren A physicist at Harvard University who directs the prestigious Woods Hole Research Centre, he will have the ear of the President as Obama's top scientific advisor.

Professor Jane Lubchenco A leading expert on the effects of global warming on oceans, she becomes the first woman administrator of the National Oceanic and Atmospheric Administration.

Congresswoman Hilda Solis The new Labour Secretary advocates providing employment through a clean energy economy. She was key sponsor of a Green Jobs Act last year.

Carole Browner Head of the Environmental Protection Agency under President Clinton, she is on the radical side of the party and will head a White House energy and climate unit.

Senator Ken Salazar Ten-gallon-hatted Colorado Senator Ken Salazar is more controversial as Interior Secretary. The top environment groups are pleased but radicals have doubts.