15 Cities to Go Green Under Clinton Plan

New York Mayor Michael Bloomberg, left, and Trenton Mayor Douglas Palmer, president of the U.S. Conference of Mayors, walk to a news conference in New York's Central Park during the C40 Large Cities Climate Summit, Tuesday May 15, 2007. City leaders from around the globe gathered Tuesday for an environmental summit hosted by former President Clinton and New York Mayor Michael Bloomberg with a message that the campaign to reverse global warming begins with the world's mayors. (AP Photo/David Karp)