Joel Makower has a good post about concerns with fraud in the carbon offset market. This is a tough, but inevitable issue, and it highlights the importance of supporting verified carbon offset programs, as well as the difficulty in national or international carbon trading. A reminder of the importance of local action.
Another reminder of the importance of local action: Brad Plumer notes a paper by Hoff Stauffer, one of the designers of the US's SO2 cap-and-trade system, arguing that a CO2 cap and trade won't work, and that anyway, the better strategy is to focus on performance standards for new greenhouse emitters--buildings, appliances, energy sources, cars. I've seen arguments on both sides for cap-and-trade, and have to confess that I don't know who to believe.
However, one point of Stauffer's is that we're facing two problems: how to reduce emissions from existing sources and how to reduce emissions from yet-to-be-created sources, and that the solutions for each of those are different. That makes sense to me, so that's going to be my new line. One of the nice things about that is that it's even easier for states and localities to take the lead in performance requirements for new developments--among this is basic stuff that we already regulate, like land use and building design. And since we in Springfield have a wonderful public utility, we can really press forward on continuing to green our energy supply as well.