Meet the pied piper of one of the most exciting green grassroots uprisings to hit the U.S. in years: Seattle Mayor Greg Nickels (D).

He's managed to get roughly 300 mayors nationwide -- from the Northwest to the deep South and everywhere in between -- to agree that it's a good idea for U.S. cities to meet or beat Kyoto Protocol targets for reducing greenhouse-gas emissions, despite the Bush administration's rejection of the treaty. Municipal leaders attending a U.S. Conference of Mayors meeting in Chicago on Monday unanimously endorsed Nickels' initiative calling on cities to do their part to stave off climate change. Before the conference vote, 165 mayors from 37 states had individually signed on to the initiative; now Nickels hopes many more will follow suit.

Granted, the U.S. Mayors Climate Protection Agreement is non-binding, so cities could climb aboard the bandwagon but not follow through on meeting the targets. But the fact that there's a bandwagon at all is noteworthy, and the timing is fortuitous. As the Senate deliberates a number of bipartisan climate amendments that have been proposed for the energy bill, mayors from New York City to Salt Lake City are sending a powerful message to D.C. lawmakers that America wants action on global warming.