Now, granted, global warming is more likely, to me, than hell, but not nearly as hot, so it's a lot more worth considering the costs involved :)
By which I mean to say that forcefully curbing CO2 emissions is a very, very hard problem. And curbing CO2 emissions without forcing developing nations not to develop is even more difficult.
Personally I think that even if global warming is every bit its cracked up to be the Bangledeshis, for example, will probably be better off with higher sea levels and first world wealth and infrastructure than they would be with existing sea levels and another century of poverty.
There are far more consequences than just that. For example, all the coral of the entire ocean would be dead or dying. Not that I expect you to care about coral; that is just one example.
Also worth noting: despite the writings of Pascal, you won't find many atheists in church. Most of them decide the cost is not worth the (odds-adjusted) expected benefits.