Daniel Altman wonders if the "green fever" that was all the rage when oil was at $140 per barrel will die away now that oil's fallen to $88 per barrel, thanks to the slump in the global economy (especially in the United States, which may or may not be in a recession already). Maybe so, but I'd argue that if we're eventually going to adopt something like a cap-and-trade system to reduce our emissions and try to sidestep drastic global warming, the best time to do so might actually be during a recession.

No, I'm not crazy. Here's how it'd work: Congress would initially set the overall economy-wide cap on emissions to something like pre-recession levels and then auction off the permits. The cap would eventually decline going forward, but for now, while the economy's slumping, emissions levels would be both well below the limit and falling anyway, which means there'd be an excess of credits, so companies could snatch them up for rock-bottom prices and have some time to learn the system. No one's really paying higher prices yet, but there's finally certainty about the future and businesses can begin planning ahead for a carbon-constrained world.

In the meantime, the government could get started on promoting clean-energy projects and various efficiency programs—from constructing smart grids to expanding mass transit to retrofitting buildings—that would take some time to take effect. As a bonus, this would help jumpstart the economy and create up to 2 million new jobs, as per the Center for American Progress's "green recovery" plan. Then, once the economy starts growing again and the price of carbon does start going up significantly, the adjustment should be much easier than if the cap were implemented during boom times and prices started spiking immediately.

--Bradford Plumer