I used to think that Bjorn Lomborg was a right-wing kook, but this video changed my mind. It's long (30 minutes) but well worth the time. Basically he makes the point that even if global warming is real and man-made (he concedes it is both), trying to reduce it still might not be a smart thing to do.
To be fair, one should be skeptical about the skeptic: one thing Lomborg doesn't take into account is the possibility of a catastrophic melting of the polar ice caps and the resulting sea-level rise flooding most of the world's coastal cities. It's hard to imagine what the silver lining would be in that scenario.