Exxon Mobil has gone on the offensive with a report claiming it spent more than $3 billion last year on expenses related to the environment. It's reputation management by a new CEO in the wake of attacks by critics over Exxon Mobil's stance on climate change. But the question is also whether this will have implications for the 2008 presidential campaign. Here's why.

The oil giant is trying to claw back its reputation under its new CEO Rex Tillerson who claims his position is no different from that of his predecessor Lee Raymond but who admits his company could have done a better job putting its case forward. In short, Exxon Mobil is going for an image makeover.

Exxon Mobil has been attacked as a climate change denier for some time. Economist Paul Krugman joined the ranks of its critics recently when he called it an "enemy of the planet" in the New York Times.If you don't subscribe, you can still read it here.

"A leaked memo from a 1998 meeting at the American Petroleum Institute, in which Exxon (which hadn't yet merged with Mobil) was a participant, describes a strategy of providing ''logistical and moral support'' to climate change dissenters, ''thereby raising questions about and undercutting the 'prevailing scientific wisdom.' '' And that's just what Exxon Mobil has done: lavish grants have supported a sort of alternative intellectual universe of global warming skepticsm'' writes Krugman."The people and institutions Exxon Mobil supports aren't actually engaged in climate research. They're the real-world equivalents of the Academy of Tobacco Studies in the movie ''Thank You for Smoking,'' whose purpose is to fail to find evidence of harmful effects"

Exxon Mobil's attempted image change comes as the public pension fund CalPERS puts heat on the company to address global warming.

Will the image makeover succeed? Probably not. Well, not when it coincides with the Competitive Enterprise Institute launching ads questioning reports about the threat of climate change ("carbon dioxide...we call it life"). The institute is one of those fronts that Krugman is referring to and is funded by Exxon Mobil

The timing of Exxon Mobil's public relations offensive and the Competitive Enterprise Institute's ad campaign is not coincidental. It all happens to comes just before the release of Al Gore's movie on climate change "An Inconvenient Truth" and it is being rightly seen as an attempt to upstage.

The ads and Exxon Mobil's stance have obvious political implications with Gore's documentary fuelling presidential speculation.