Following sharp criticism from Britain's Royal Society, Exxon Mobil [3] says it is reviewing which of the groups "that challenge the scientific validity [4] of concerns about global warming [5]" it will continue to fund. Exxon gave at least $6.8 million to nonprofit groups in 2005, including the Competitive Enterprise Institute [6], which recently ran "television ads [7] that argued that carbon dioxide, widely seen as the main global-warming gas, is helpful." The Royal Society [8], made up of Britain's leading scientists, took the "unprecedented step" of writing to Exxon [9] to demand the oil giant stop funding groups that have "misrepresented the science of climate change by outright denial of the evidence." The Society also criticized Exxon's "corporate citizenship reports," which claim that "gaps in the scientific basis" make it very difficult to link climate change and human activity. In the Guardian, George Monbiot writes [10] about the history of corporate climate change denial, going back to the PR firm APCO [11], Philip Morris [12], PR Watch "usual suspect" Steve Milloy [13] and his front group, the Advancement of Sound Science Coalition [14].