A big part of the global warming denial industry argument is the contention that somehow scientists and policymakers over-inflate the threat of global warming to continue the flow of government research dollars.
Many, including the DeSmogBlog, have refuted the claim, but none quite so well as our friend and author Chris Mooney  did to a question posed by "skeptic" Bill Gray at a recent symposium.
Mooney writes: 
"The highlight for me (and for many in the audience, I think) came when Bill Gray got up and asked his question. If I can paraphrase, in essence he asked whether the scientists who support human-caused global warming are doing so in part because of government research funding--or in other words, doesn't such funding create a strong incentive for researchers who apply for grants to assume that global warming is actually a "problem" in the first place, and build their research around that assumption?
I replied that there ought to be a strong contrary incentive: Namely, any scientist who unseats the global warming consensus, who proves that it isn't a problem, ought to be able to win quite a lot of fame and renown for doing so. And so, once again, science ought to check itself..." (emphasis added)
Check out Mooney's latest book Storm World: hurricanes, politics and the battle over global warming.