What happens if Congress can't—or won't—pass a climate bill in the next two years? Does that mean Obama will just have to scrap his promise to regulate greenhouse-gas emissions? No, not necessarily. As we've discussed before, and as Marc Ambinder pointed out yesterday, thanks to a 2007 Supreme Court ruling, the EPA has the option of using the existing Clean Air Act to regulate CO2 from power plants and large industrial facilities. Here's Ambinder's take:

If Obama decides to do this, climate change conservatives will go ape. An end-run around Congress. An illegal intervention by the executive branch. No public debate, etc. But it would work, and it would allow [Obama] to tackle, say, health care, without the distraction of having to also put through another major piece of reform legislation.

It's unclear, exactly, how the Clean Air Act would be adapted to greenhouse-gas regulation. Some Obama advisers think the EPA has the authority to design a national cap-and-trade system on its own that would build on existing state efforts (I wrote a piece for Audubon over the summer detailing how states were taking the lead on climate legislation). Others think that using existing law will be much messier than that: Bill Kovacs of the Chamber of Commerce sketches out a doomsday scenario in which the economy gets bogged down in complex new EPA rules. His reading of the Clean Air Act suggests, for instance, that "all new construction that will result in the emission of 250 tons of greenhouse gases will come to a halt until [permits] can be obtained, [which] take between 1-2 years to obtain, cost hundreds of thousands of dollars and involve, on a case—by—case basis, the analysis of the best available technology."

Dave Roberts just put up a smart post detailing the pluses and minuses of a Clean Air Act approach. On the negative side, Obama would be instituting a large new regulatory regime by executive fiat, without extended public debate, a move could prove reversible by future Republican presidents. On the upside, Obama would be able to tackle a dire issue even if the GOP's intent on filibustering any and all emissions legislation. Dave's post gets into the nitty-gritty here, though I think he skips over one major pitfall of the Clean Air Act option: It's doubtful that the EPA has enough manpower right now to regulate CO2 properly. The agency is already overextended, and, from what I've heard, it would be quite difficult to add a huge new responsibility like this without additional resources from Congress. (Also, as Kevin Drum observes, executive rule-making isn't exactly a speedy process.)

Now, I have a slightly different read on all this. I tend to think Obama and his advisers are (mostly) talking about using the Clean Air Act as a way of increasing their leverage with Congress. The Chamber of Commerce and other business groups are very, very worried about the EPA taking this route, without congressional input. My guess is industry would rather that Congress design a flexible cap-and-trade program than have unelected bureaucrats use outdated laws, and would be willing to nudge a few conservative politicians if necessary. That means Republicans may not be able to stymie carbon regulations for long, since the choice isn't between something or nothing; it's between Congress capping emissions or Obama doing it for them. As the saying goes, better to sit at the table than find yourself on the menu.

At the same time, I'd wager that many congressional Blue Dogs and other swing-district Democrats would prefer to let the Obama administration go ahead and regulate carbon dioxide on its own. That way the president gets blamed for any energy price increases that might result—and Congress gets to avoid a contentious vote. In fact, part of me thinks the endgame here could resemble what California did in 2006: Congress would approve the broad outlines of a cap-and-trade regime, but leave the difficult implementation choices up to a non-partisan executive body, akin to California's Air Resources Board. That way, representatives can tell their constituents that they "did something" about global warming, while blaming any adverse consequences on the EPA's implementation plan. Business groups won't like this approach, but they may eventually prefer it to having the Clean Air Act rammed down their throats.

--Bradford Plumer