Tim O'Reilly makes the most cogent argument I've yet seen on why we should believe in global warming and act accordingly, even if we don't fully buy into the hype: The downside to belief is quite small. The upside is quite big.
In other words, it's a near-perfect application of Pascal's Wager, as Tim points out:
In my talks, I've argued that climate change provides us with a modern version of Pascal's wager: if catastrophic global warming turns out not to happen, the steps we'd take to address it are still worthwhile.
Given that there's even a reasonable risk of disruptive climate change, any sensible person should decide to act. It's insurance.
The risk of your house burning down is small, yet you carry homeowner's insurance...We don't need to be 100 percent sure that the worst fears of climate scientists are correct in order to act. All we need to think about are the consequences of being wrong.
I've tended to fall on the side of the skeptics, though a recent Foreign Policy article has me nearly persuaded. I haven't resisted because I know that global warming is a hoax, but rather because I haven't been fully convinced by the evidence. (Well, really, it's because I just like to be contrarian, but don't tell anyone.)
But I buy Tim's rationale. The downsides to a better environment, more fuel-efficient cars, etc., are not downsides at all. They're things I'd like regardless of whether the world is burning up or not. So why not?