More than 100 scientists — including a number of Canadian government scientists and university professors — have signed a full-page newspaper ad denouncing U.S. President Barack Obama's remarks about climate change last November as "untrue."

"Mr. President , your characterization of the scientific facts regarding climate change and the degree of certainty informing the scientific debate is simply incorrect," said the ads paid for by the Cato Institute that ran Monday in the New York Times, the Washington Post, the Washington Times, the Chicago Tribune and the Los Angeles Times. The ads cite evidence, referenced in four scientific papers, that the climate is not changing significantly.

Obama will be hosting a summit of world leaders in April to help forge a UN agreement on global warming. In recent months, the new president has signalled he is ready for a shift in U.S. environmental policy, prioritizing clean energy and slashing greenhouse gas emissions through a cap-and-trade program in order to reduce U.S. greenhouse gas emissions to 1990 levels by 2020.

'I think this should be viewed as a statement by the Cato institute, who are initiating it, directing it and paying for it. It's not the scientists who are doing that.'— Sheldon Rampton, Centre for Media and Democracy

The Cato Institute is a think-tank that advocates against government intervention in free markets and people's individual lives.

Patrick Michaels, senior fellow of environmental studies at the Cato Institute, said the ads are intended to open up debate.

"When Obama says the science is clear, that's hardly the case," Michaels said, accusing the president of stifling debate with his November remarks.

He added that the Cato Institute has run similar newspaper ads signed by economists that criticized Obama's Jan. 9 statement about the need for an economic stimulus package.

Michaels, who is also a professor of environmental sciences at the University of Virginia, added that scientists were recruited from various mailing lists to prove there is a lot of disagreement on the fact surrounding climate change.

New York Times ad would cost $150,000

He confirmed that none of the scientists paid for the ads, which would have cost hundreds of thousands of dollars. The New York Times ad alone would have cost over $150,000, based on the newspaper's published ad rates.

Among the Canadians who signed the ad were:

• Ian Clark, professor of Earth Sciences, University of Ottawa.
• Paul Copper, Laurentian University (Emeritus).
• Susan Crockford, University of Victoria.
• Christopher Essex, University of Western Ontario.
• Neil Hutton, past president, Canadian Society of Petroleum Geologists.
• Wayne Goodfellow, University of Ottawa.
• David Nowell, former chairman, NATO Meteorology Canada.
• Peter Salonius, Canadian Forest Service.
• Ross McKitrick, University of Guelph.

Clark, whose research involves groundwater contamination, groundwater resources, and climate studies said he found the content of the ad compelling.

"I feel very strongly that the whole issue had to be look at a little bit more closely before grave public policies are developed … far reaching and expensive public policies," he said, adding that he had no previous affiliation with the Cato Institute.

However, he said he wants people to know about the existence of data that refutes climate change and believes that the government will neglect other environmental issues such as urbanization and overfishing if it is too focused on dealing with climate change.

Ad doesn't reflect Ottawa's view: spokeswoman

Goodfellow, an environmental geochemist and an adjunct professor at the University of Ottawa, declined to comment, saying he is an employee of Natural Resources Canada and would need government clearance to speak on the matter.

The Canadian Forest Service is a branch of Natural Resources Canada also. However, Natural Resources Canada spokeswoman Patti Robson, said the fact that a soil microbiologist with the forest service, Peter Salonius, signed the ad, including his affiliation, does not reflect the opinion of the Canadian Forest Service, Natural Resources Canada, or the government of Canada.

She added that employees such as Salonius, a soil microbiologist, have the right to express their opinions as private citizens, but indicating their affiliation with the department would be misleading. As of late Monday afternoon, Salonius had not responded to requests for an interview.

Corporations may be behind ad, group says

Sheldon Rampton, research director for the Centre for Media and Democracy, an organization that tries to expose spin and propaganda from governments and corporations, suggested that corporate influence might be behind the Cato Institute's ads.

"Even think-tanks don't pay for this unless there's someone who's willing to shoulder the cost," he said.

He said it isn't uncommon for corporations to bring together a think-tank and a group of experts to speak on their behalf.

"It's actually fairly standard PR technique when you want to sway public opinion on your behalf," he said, referring to it as the third-party technique. He added that the overall campaign to sow doubt about climate change has so far been successful in preventing the U.S. government from acting to slow greenhouse gas emissions.

According to the Cato Institute, the climate change ads are funded from general revenues. Of those, 75 per cent comes from individual donors, with foundations and 18 corporations covering the rest, according to the institute's 2007 annual report. Five of the corporate donors that year were car manufacturers. The others, including the American Petroleum Institute, Wal-Mart, Microsoft and Visa, come from a range of industries.

Rampton cautioned against giving the institute's climate change ad too much weight.

"This practice of collecting scientists and putting them in ads, should not be viewed as reflecting the mainstream views of the scientific community," he said, adding that many of the scientists who signed the ad are not climate specialists.

"I think this should be viewed as a statement by the Cato institute, who are initiating it, directing it and paying for it. It's not the scientists who are doing that."

But at least one of the scientists who signed the ad disagree that it matters who paid for the ad. He said he had heard of the Cato Institute before he signed the letter, but believes that is "immaterial."

"If somebody's reading the ad, the larger public, they're going to read the ad. Most people aren't going to know what the Cato Institute is," he said, adding that he supported the ad not because of who it was from, but because of the message.

"They've got money, they've go support and they can afford an ad like that .… It doesn't matter to me where you get your money from as long as it's legal. If my understanding of an issue aligns with yours, then we're allies."