We've long noted the growing importance of local and state officials in the effort to halt global warming, and now research shows that these sub-national political bodies are making a real difference. In a "Brief Communication" in the November 17 edition of Nature, Brendan Fisher and Robert Costanza from the University of Vermont show that, in the United States, up to a third of the US population lives in areas that either already have or will soon adopt policies in accord with the Kyoto protocols. Moreover, the Kyoto-friendly regions account for nearly one-half of the total US GDP -- a total economic output greater than that of Japan, currently the world's second-largest economy.

The catch is that there are few mechanisms to enforce compliance at the sub-national level, so meeting the policy commitments will be even more difficult than under a national system. Conversely, as the authors note, "the local nature of these initiatives could make it possible to develop adaptable, site-specific plans for reducing greenhouse-gas emissions."