More than 100 cities across 35 US states have signed up to an initiative to implement measures to meet Kyoto targets, despite rejection of the Protocol by the Bush Administration.
Signatories, including New York, now represent close to 30 million people.
Among the proposals to cut greenhouse gas emissions by 7% by 2010 are running municipal vehicles on gas or electricity, investment in renewables, planting trees, promoting car pooling, improving public transport and providing cycle lanes.
Each city has signed up to produce a greenhouse gas inventory and measures to reduce it.
In a separate measure a number of states, again including New York, have signed up to a carbon trading deal.