by Andrew C. Revkin

For more than a decade the Global Climate Coalition, a group representing industries with profits tied to fossil fuels, led an aggressive lobbying and public relations campaign against the idea that emissions of heat-trapping gases could lead to global warming.

"The role of greenhouse gases in climate change is not well understood," the coalition said in a scientific "backgrounder" provided to lawmakers and journalists through the early 1990s, adding that "scientists differ" on the issue.

But a document filed in a federal lawsuit demonstrates that even as the coalition worked to sway opinion, its own scientific and technical experts were advising that the science backing the role of greenhouse gases in global warming could not be refuted.

"The scientific basis for the Greenhouse Effect and the potential impact of human emissions of greenhouse gases such as CO2 on climate is well established and cannot be denied," the experts wrote in an internal report compiled for the coalition in 1995.

The coalition was financed by fees from large corporations and trade groups representing the oil, coal and auto industries, among others. In 1997, the year an international climate agreement that came to be known as the Kyoto Protocol was negotiated, its budget totaled $1.68 million, according to tax records obtained by environmental groups.

Throughout the 1990s, when the coalition conducted a multimillion-dollar advertising campaign challenging the merits of an international agreement, policy makers and pundits were fiercely debating whether humans could dangerously warm the planet. Today, with general agreement on the basics of warming, the debate has largely moved on to the question of how extensively to respond to rising temperatures.

Environmentalists have long maintained that industry knew early on that the scientific evidence supported a human influence on rising temperatures, but that the evidence was ignored for the sake of companies' fight against curbs on greenhouse gas emissions. Some environmentalists have compared the tactic to that once used by tobacco companies, which for decades insisted that the science linking cigarette smoking to lung cancer was uncertain. By questioning the science on global warming, these environmentalists say, groups like the Global Climate Coalition were able to sow enough doubt to blunt public concern about a consequential issue and delay government action.

George Monbiot, a British environmental activist and writer, said that by promoting doubt, industry had taken advantage of news media norms requiring neutral coverage of issues, just as the tobacco industry once had.

"They didn't have to win the argument to succeed," Mr. Monbiot said, "only to cause as much confusion as possible."

William O'Keefe, at the time a leader of the Global Climate Coalition, said in a telephone interview that the group's leadership had not been aware of a gap between the public campaign and the advisers' views. Mr. O'Keefe said the coalition's leaders had felt that the scientific uncertainty justified a cautious approach to addressing cuts in greenhouse gases.

The coalition disbanded in 2002, but some members, including the National Association of Manufacturers and the American Petroleum Institute, continue to lobby against any law or treaty that would sharply curb emissions. Others, like Exxon Mobil, now recognize a human contribution to global warming and have largely dropped financial support to groups challenging the science.

Documents drawn up by the coalition's advisers were provided to lawyers by the Association of International Automobile Manufacturers, a coalition member, during the discovery process in a lawsuit that the auto industry filed in 2007 against the State of California's efforts to limit vehicles' greenhouse gas emissions. The documents included drafts of a primer written for the coalition by its technical advisory committee, as well as minutes of the advisers' meetings.

The documents were recently sent to The New York Times by a lawyer for environmental groups that sided with the state. The lawyer, eager to maintain a cordial relationship with the court, insisted on anonymity because the litigation is continuing.

The advisory committee was led by Leonard S. Bernstein, a chemical engineer and climate expert then at the Mobil Corporation. At the time the committee's primer was drawn up, policy makers in the United States and abroad were arguing over the scope of the international climate-change agreement that in 1997 became the Kyoto Protocol.

The primer rejected the idea that mounting evidence already suggested that human activities were warming the climate, as a 1995 report by the United Nations Intergovernmental Panel on Climate Change had concluded. (In a report in 2007, the panel concluded with near certainty that most recent warming had been caused by humans.)

Yet the primer also found unpersuasive the arguments being used by skeptics, including the possibility that temperatures were only appearing to rise because of flawed climate records.

"The contrarian theories raise interesting questions about our total understanding of climate processes, but they do not offer convincing arguments against the conventional model of greenhouse gas emission-induced climate change," the advisory committee said in the 17-page primer.

According to the minutes of an advisory committee meeting that are among the disclosed documents, the primer was approved by the coalition's operating committee early in 1996. But the approval came only after the operating committee had asked the advisers to omit the section that rebutted the contrarian arguments.

"This idea was accepted," the minutes said, "and that portion of the paper will be dropped."

The primer itself was never publicly distributed.

Mr. O'Keefe, who was then chairman of the Global Climate Coalition and a senior official of the American Petroleum Institute, the lobby for oil companies, said in the phone interview that he recalled seeing parts of the primer.

But he said he was not aware of the dropped sections when a copy of the approved final draft was sent to him. He said a change of that kind would have been made by the staff before the document was brought to the board for final consideration.

"I have no idea why the section on the contrarians would have been deleted," said Mr. O'Keefe, now chief executive of the Marshall Institute, a nonprofit research group that opposes a mandatory cap on greenhouse gas emissions.

"One thing I'm absolutely certain of," he said, "is that no member of the board of the Global Climate Coalition said, ‘We have to suppress this.' "

Benjamin D. Santer, a climate scientist at Lawrence Livermore National Laboratory whose work for the Intergovernmental Panel on Climate Change was challenged by the Global Climate Coalition and allied groups, said the coalition was "engaging in a full-court press at the time, trying to cast doubt on the bottom-line conclusion of the I.P.C.C." That panel concluded in 1995 that "the balance of evidence suggests a discernible human influence on global climate."

"I'm amazed and astonished," Dr. Santer said, "that the Global Climate Coalition had in their possession scientific information that substantiated our cautious findings and then chose to suppress that information."