Philip Cooney, chief of staff for the White House Council on Environmental Quality, often would subtly alter documents -- for example adding "significant and fundamental" before the word "uncertainties" -- to create an air of doubt about findings few scientists dispute, said the daily.

On one document, Cooney added the work "extremely" to the sentence: "The attribution of the causes of biological and ecological changes to climate change or variability is extremely difficult."

The alterations Cooney made on drafts of several reports issued in 2002 and 2003 often appeared in the final reports, said the daily.

Cooney, who before working at the White House in 2001 was a lobbyist at the American Petroleum Institute and led the oil industry's fight against limits on greenhouse gases, is a lawyer with a bachelor's degree in economics and lacks scientific training, the daily said.

Rick Piltz, who resigned in March as a senior associate in the office that coordinates government climate research, said in a memorandum sent to top US officials last week that editing of scientific reports tainted official efforts to establish the causes of climate change.

"Each administration has a policy position on climate change," Piltz wrote, according to The New York Times. "But I have not seen a situation like the one that has developed under this administration during the past four years, in which politicization by the White House has fed back directly into the science program in such a way as to undermine the credibility and integrity of the program."

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