Some staffer or other at The New Republic wrote a short editorial arguing that China and India's ostensible refusal to curb their own greenhouse emissions shouldn't give the United States an excuse to sit on its hands. I'll just add one other thing. I've heard people suggest that if the United States put a cap on carbon emissions--through a carbon tax or cap-and-trade program--then our manufacturers would just move their production to, say, China and merrily continue their polluting ways, free of hassle. It's a reasonable fear, and I actually haven't heard many people address it.

At the Kerry-Gingrich debate on global warming last week, though, Kerry mentioned that if worst came to worst, the United States and Europe could always use trade policy to force China and India to change course. Presumably that would mean carbon taxes on imports. I'm not sure how that would work in practice, or whether it would even pass muster with the WTO (Kerry admitted that he wasn't sure, either), but it's a possibility that at least some Democrats seem to be discussing.