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.

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.

• David Adam, environment correspondent
• The Guardian, Tuesday 14 April 2009
• Article history

Water shortage will cause greater ruin than peak oil. Photograph: Pedro Armestre/AFP/Getty Images

Almost nine out of 10 climate scientists do not believe political efforts to restrict global warming to 2C will succeed, a Guardian poll reveals today. An average rise of 4-5C by the end of this century is more likely, they say, given soaring carbon emissions and political constraints.

Such a change would disrupt food and water supplies, exterminate thousands of species of plants and animals and trigger massive sea level rises that would swamp the homes of hundreds of millions of people.

The poll of those who follow global warming most closely exposes a widening gulf between political rhetoric and scientific opinions on climate change. While policymakers and campaigners focus on the 2C target, 86% of the experts told the survey they did not think it would be achieved. A continued focus on an unrealistic 2C rise, which the EU defines as dangerous, could even undermine essential efforts to adapt to inevitable higher temperature rises in the coming decades, they warned.

The survey follows a scientific conference last month in Copenhagen, where a series of studies were presented that suggested global warming could strike harder and faster than realised.

The Guardian contacted all 1,756 people who registered to attend the conference and asked for their opinions on the likely course of global warming. Of 261 experts who responded, 200 were researchers in climate science and related fields. The rest were drawn from industry or worked in areas such as economics and social and political science.

The 261 respondents represented 26 countries and included dozens of senior figures, including laboratory directors, heads of university departments and authors of the 2007 report from the Intergovernmental Panel on Climate Change (IPCC).

The poll asked the experts whether the 2C target could still be achieved, and whether they thought that it would be met: 60% of respondents argued that, in theory, it was still technically and economically possible to meet the target, which represents an average global warming of 2C since the industrial revolution. The world has already warmed by about 0.8C since then, and another 0.5C or so is inevitable over coming decades given past greenhouse gas emissions. But 39% said the 2C target was impossible.

The poll comes as UN negotiations to agree a new global treaty to regulate carbon pollution gather pace in advance of a key meeting in Copenhagen in December. Officials will try to agree a successor to the Kyoto protocol, the first phase of which expires in 2012. The 2C target is unlikely to feature in a new treaty, but most of the carbon cuts proposed for rich countries are based on it. Bob Watson, chief scientist to Defra, told the Guardian last year that the world needed to focus on the 2C target, but should also prepare for a possible 4C rise.

Asked what temperature rise was most likely, 84 of the 182 specialists (46%) who answered the question said it would reach 3-4C by the end of the century; 47 (26%) suggested a rise of 2-3C, while a handful said 6C or more. While 24 experts predicted a catastrophic rise of 4-5C, just 18 thought it would stay at 2C or under.

Some of those surveyed who said the 2C target would be met confessed they did so more out of hope rather than belief. “As a mother of young children I choose to believe this, and work hard toward it,” one said.

“This optimism is not primarily due to scientific facts, but to hope,” said another. Some said they thought geoengineering measures, such as seeding the ocean with iron to encourage plankton growth, would help meet the target.

Many of the experts stressed that an inability to hit the 2C target did not mean that efforts to tackle global warming should be abandoned, but that the emphasis is now on damage limitation.