A White House official who once led the oil industry's fight against limits on greenhouse gases has repeatedly edited government climate reports in ways that play down links between such emissions and global warming, according to internal documents.

In handwritten notes on drafts of several reports issued in 2002 and 2003, the official, Philip A. Cooney, removed or adjusted descriptions of climate research that government scientists and their supervisors, including some senior Bush administration officials, had already approved.

Mr. Cooney is chief of staff for the White House Council on Environmental Quality, the office that helps devise and promote administration policies on environmental issues. Before coming to the White House in 2001, he was the "climate team leader" and a lobbyist at the American Petroleum Institute, the largest trade group representing the interests of the oil industry. A lawyer with a bachelor's degree in economics, he has no scientific training.

The alterations are sometimes as subtle as the insertion of an adjective, but cause a clear shift in the meaning of the documents.

For example, a sentence in an October 2002 draft of a regularly published summary of government climate research, "Our Changing Planet," originally read: "Many scientific observations indicate that the Earth is undergoing a period of relatively rapid change...."

Mr. Cooney's neat, compact notes modified the sentence to read: "Many scientific observations point to the conclusion that the Earth may be undergoing a period of relatively rapid change...."

In places where uncertainties in climate research were described, Mr. Cooney added qualifiers like "significant" and "fundamental."

Another document showing the same pattern of changes is the 2003 Strategic Plan for the United States Climate Change Science Program, a thick report describing the reorganization of government climate research that was requested by Mr. Bush in his first speech on the issue, in June 2001.

That document was reviewed by an expert panel assembled in 2003 by the National Academy of Sciences. The scientists largely endorsed the administration's research plan, but they warned that the administration's procedures for vetting reports on climate could result in excessive political interference with science.

Now it appeared that some interference was happening even before the research had gotten into full swing, said Dr. William H. Schlesinger, who was on the review committee and is dean of the Nicholas School of the Environment and Earth Sciences at Duke University.

After some of Mr. Cooney's changes to the drafts were described to Dr. Schlesinger by The New York Times, he said several seemed "egregious."

"They're trying to throw enough uncertainty in so that either policymakers or the public would not want to take a firm stand on it," he said.