In the first big study of the impact of the recession on climate change, the IEA found that CO2 emissions from burning fossil fuels had undergone "a significant decline" this year — further than in any year in the last 40.
....Falling industrial output is largely responsible for the plunge in CO2 , but [...] for the first time, government policies to cut emissions have also had a significant impact. The IEA estimates that about a quarter of the reduction is the result of regulation, an "unprecedented" proportion. Three initiatives had a particular effect: Europe's target to cut emissions by 20 per cent by 2020; US car emission standards; and China's energy efficiency policies.
Europe's cap-and-trade system didn't start out very strongly, but the fact is that nobody really expected it to. Phase 2, however, is working better, and Phase 3 will be better still. If we learn from their experience, we can avoid the early stumbles and put in place a decent (and steadily improving) program right out of the gate. Ten years ago would have been a good time to start, but failing that, this year will have to do.