Coyote Blog has a detailed post collecting skeptics' thoughts on the global warming debate. It concludes with a crucial thought: we can't do something "just in case" global warming is as bad as the models predict, becausing that "doing something" has terrible costs:
This would be a perfectly reasonable approach if cutting back on CO2 production was nearly cost-free. But it is not. The burning of hydrocarbons that create CO2 is an entrenched part of our lives and our economies. Forty years ago we might have had an easier time of it, as we were on a path to dramatically cut back on CO2 production via what is still the only viable technology to massively replace fossil fuel consumption -- nuclear power. Ironically, it was environmentalists that shut down this effort, and power industries around the world replaced capacity that would have gone nuclear mostly with coal, the worst fossil fuel in terms of CO2 production (per btu of power, Nuclear and hydrogen produce no CO2, natural gas produces some, gasoline produces more, and coal produces the most).
Just halting CO2 production at current levels (not even rolling it back) would knock several points off of world economic growth. Every point of economic growth you knock off guarantees you that you will get more poverty, more disease, more early death. If you could, politically, even make such a freeze stick, you would lock China and India, nearly 2 billion people, into continued poverty just when they were about to escape it. You would in the process make the world less secure, because growing wealth is always the best way to maintain peace. Right now, China can become wealthier from peaceful internal growth than it can from trying to loot its neighbors. But in a zero sum world created by a CO2 freeze, countries like China would have much more incentive to create trouble outside its borders.
The whole post is highly recommended reading.