According to ExxonMobil's web site, $6.8 million of nearly $133 million in 2005 contributions globally for "public information and policy research" was distributed to more than 140 think-tanks, universities, foundations, associations and other groups. Some of those have publicly disputed the link between greenhouse gas emissions and global warming.
In September, ExxonMobil admitted that it donates to companies that research "significant policy issues and promote informed discussion on issues of direct relevance to the company."
Alden Meyer, a leading member of the Union of Concerned Scientists, says that ExxonMobil mirrored tactics used by tobacco companies, spreading uncertainty by misrepresenting peer-reviewed scientific studies or cherry-picking facts. Dr. James McCarthy, a professor at Harvard University, said the company has sought to "create the illusion of a vigorous debate" about global warming.
If these claims prove true, nobody would argue with their successes, as can be seen here and here.