Philip Cooney, chief of staff for the White House council on environmental quality, intervened to blur the conclusions of government scientists before they were published.

Mr Cooney not only lacks any scientific training but was a former lobbyist with the oil industry’s largest trade group before he entered the White House in 2001.

Sometimes his editing consisted of inserting words such as “significant and fundamental” before the word “uncertainties” to sow doubt about the assertions of scientists.

At other times his brush was broader. For example, in the draft text of a November 2002 policy paper, Mr Cooney deleted a paragraph which gave warning that melting glaciers would change flood patterns and threaten native populations because the assertion was “straying from research in speculative findings/musings”.

The leak, to The New York Times, is at least the third time in the past four years that the White House has been caught meddling with scientific findings. It came a day after President Bush, after talks with Tony Blair, ducked a direct question about whether he believed climate change was man-made. The Prime Minister is striving to clinch a post- Kyoto deal on climate change, to include the US, India and China, the world’s biggest polluters, when leaders of the richest seven nations, and Russia, meet for the G8 summit at Gleneagles next month.

But Mr Bush gave little hint when he met the Prime Minister at the White House on Tuesday that he is prepared to loosen his objections to binding commitments on the US. He said that America was spending more than any other country on research into alternative fuels. But he said that it was acting chiefly out of economic and national security concerns. And he pointedly failed to accept the link between greenhouse gases and global warming. The jury was still out as far as the White House was concerned, he said. “We want to know more about it. It’s easier to solve a problem when you know a lot about it.”

He has previously committed his Administration to slowing the growth of harmful emissions, but his targets are voluntary. Such a standpoint is reflected in Mr Cooney’s neat, meticulous handwritten annotations that litter Administration environmental papers.

In one October 2002 policy paper, Our Changing Planet, Mr Cooney added the word “extremely” to the sentence: “The attribution of the causes of biological and ecological changes to climate change or variability is extremely difficult.”

In the same paper, he made subtle changes to one sentence with the effect that its meaning was altered significantly. The original, written by government scientists and approved by their supervisors, stated: “Many scientific observations indicate that the Earth is undergoing a period of relatively rapid change.”

After Mr Cooney’s intervention, it read: “Many scientific observations point to the conclusion that the Earth may be undergoing a period of relatively rapid change.” Mr Cooney’s editing fits a pattern. In 2002 the Administration published its annual report on air pollution trends without any section on global warming, and in 2003 the White House intervened to cut a section from an Environmental Protection Agency report which described the risks from rising global temperatures, replacing them with a few non-committal paragraphs.

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