Last month, The New Yorker's Jane Mayer published a long piece on how billionaires David and Charles Koch fund a variety of libertarian causes—from Tea Parties to the Cato Institute. Given that the brothers own Koch Industries, the second-largest privately held oil company in America, it's no surprise that the Kochs also like to wade into the carbon/climate debate. (The Koch-funded wing of the Smithsonian Natural History Museum, for instance, has a... creative... exhibit on climate change.) But how important are the Kochs, in the grand climate-skeptic scheme of things?

Pretty central. Via Andrew Restuccia, here's an old Greenpeace report finding that the Kochs have sent nearly $50 million over the past five years to "climate-denial front groups"—more than even ExxonMobil. That includes, for instance, $5 million to Americans for Prosperity (AFP) for its "Hot Air Tour" attacking climate policy. Mind you, some of the links Greenpeace details seem slightly overstated. The Kochs give lots of money to the Heritage Foundation, for instance, which does employ several climate-skeptic pseudo-experts. But there are plenty of reasons the Kochs might want to bankroll Heritage—the group promotes a wide variety of right-wing causes. On the other hand, it's also true that none of these Koch-funded groups ever need to worry that their climate-denial message might run afoul of these particular funders. So it'd be naive to think it's wholly inconsequential that two climate-denying oil barons are lavishing money on conservative think tanks.

Lobbying, on the other hand, is pretty clear-cut. Greenpeace notes that between 2006 and 2009, the Koch brothers—along with Koch Industries and Koch family members—spent $37.9 million advocating on energy issues, behind only ExxonMobil and Chevron. One place where the Kochs have been extremely active in shaping the climate debate of late is in California. Flint Hills Resources, a subsidiary of Koch Industries, recently gave $1 million to the campaign to overturn California's climate law by ballot initiative, and Koch-backed groups are working overtime to stir up opposition to the law.

By the way, the California debate is interesting because not all the oil companies are lined up alongside the Kochs. The big oil giants, such as ExxonMobil, BP, and Chevron, are all staying neutral. Shell actually opposes the repeal campaign. It's mainly the mid-sized refiners—Koch Industries and Valero and Tesoro—that are fighting hardest to scrap the climate law. One possibility is that the major oil companies think they'll be able to handle the new carbon restrictions better than their smaller competitors. The Koch brothers, at least, appear to agree.

(Flickr photo credit: saccamtoiloi_90)