More than 100 US mayors are attending a summit in the western city of Seattle to share and develop policies aimed at tackling climate change.
The mayors attending hail from Miami to New Jersey
Seattle's own mayor said it was up to individual cities to take on the principles of the Kyoto Protocol, which the US government has not signed up to.
"Our federal government has ignored the problem," Greg Nickels said.
Seattle says it has exceeded Kyoto goals itself, cutting greenhouse gas emissions to 8% below 1990 levels.
Most of the 110 mayors at the summit are keen to highlight the distance between their policies on climate change and those of the federal government 4,500km away, the BBC's Vincent Dowd reports from the conference.
Democratic and Republican mayors seem to have decided the need to act on global warming is urgent - or at least the need to show their voters they are taking an interest, our reporter adds.
Kyoto "was the first time the community of nations came together to solve a common problem that didn't involve war and so the fact that the United States didn't join in... was a huge disappointment", Mr Nickels said at the start of the summit.
"But that doesn't give us an excuse for taking no action."
Former US President Bill Clinton is due to address the conference with his ideas on how the US can lead on the issue.
It is thought he will announce his Clinton Foundation is to become more involved with climate change research.