Nowadays, a growing number of conservatives are admitting that, yes, okay, global warming is real. But, they add, we shouldn't impose binding caps on CO2 because it's too costly, and anyway, the only thing that will save us is awesome new technology. For variations on the theme, see Newt Gingrich or Jim Manzi. Some of these folks seem to have great faith in Congress's ability to pick out the technologies that will save us, so they suggest that the government should just ramp up R&D spending on mitigation and adaptation and call it a day.

The liberal response is to say, yes, we need some technological advances to avert catastrophic global warming, but to get those, we mostly need to cap carbon emissions and let the market decide how best to adjust. That's the best way to spur innovation. Now, I'm a kneejerk lefty, so I've always thought this was basically correct, but here's a chart putting the argument in graphic form (via ED's excellent climate blog):



What are we looking at here? This is from a Carnegie Mellon research paper looking at patent filings for sulfur dioxide-control technologies for electric power plants. The government had been spending money on research for this stuff for a long time, but it was only in the late 1960s—after Congress passed the Clean Air Act, in all its regulatory glory—that the patents started flooding in. Regulation, it seems, and not R&D spending per se, helped drive innovation.