Let's get some good news for a change. I've written before that the climate bills in Congress could stand to be a lot more ambitious, and the reason is that U.S. emissions are already plunging at a fairly rapid clip. Case in point: The Energy Information Administration just put out a new report finding that CO2 emissions in the United States from energy sources—that is, excluding cow belches and landfills and whatnot—are now down 10 percent from 2005 levels.

Is that all due to the economic slump? Nope. Only about one-third of the drop is from the recession. Another third is due to the U.S. economy getting more energy efficient—probably a response to the sky-high oil prices in the summer of 2008. And the other third is due to the fact that electric utilities are switching to cleaner energy sources. Power companies are swapping out dirty coal for natural gas (which emits about half the CO2), in part because new discoveries of the latter have caused prices to drop. Renewable power is also gaining ground. Here's a graph:

Interestingly, as Joe Romm highlights, the EIA expects these trends to continue on their own in the years ahead: "[L]onger-term trends continue to suggest decline in both the amount of energy used per unit of economic output and the carbon intensity of our energy supply, which both work to restrain emissions."

This report deserves a lot more attention, especially if Congress ever starts debating climate legislation. Right now, the Kerry-Graham-Lieberman bill would try to cut greenhouse gas emissions 17 percent below 2005 levels by 2020. But we're already more than halfway there—and it's quite likely we'll drop a bit more even without a bill. So there's no good reason why Congress can't craft a much more ambitious carbon cap. The EIA report suggests that meeting that target would be pretty easy.

And yes, Obama pledged a 17 percent cut at Copenhagen, but at the moment, even when you add up all the Copenhagen pledges, the planet still seems to be on course for a 3°C or 4°C rise in temperatures by the end of the century, well past what many climatologists consider the "safe" limit of 2°C. If the world wants to avoid a major calamity (and that seems like a good idea), then something big has to change, and more-aggressive-than-promised U.S. action would certainly be a start.