Texas, which is President George W. Bush's home state, has promoted more renewable energy use to help the state become energy independent and fight air pollution.

Still, the report warned that a fragmented, state-by-state approach to climate change policy will be less effective than coming up with a national plan.

"These state initiatives are achieving real (emission) reductions and are opportunities for learning, but they should not be viewed as a substitute for a comprehensive national policy that includes mandatory measures," said Eileen Claussen, President of the Pew Center.

The Pew Center reviewed emissions reduction programs in nine states: Georgia, Massachusetts, Minnesota, Nebraska, New Jersey, North Carolina, Oregon, Texas and Wisconsin.

The report said while climate change action is underway at the local level, states face some limits, such as having little funding available to fight global warming and constitutional restrictions from entering foreign agreements on the issue.

The report also pointed out that not all states are interested in fighting global warming and some legislatures have prevented state agencies from pursuing any programs that would reduce greenhouse gases.

The European Union and Japan have said the United States should do more to fight global warming, because the U.S. market is the world's biggest energy consumer and also largest producer of greenhouse gas emissions.

Many U.S. allies have strongly criticized Bush for pulling the United States last year out of the Kyoto treaty that seeks to reduce greenhouse gas emissions produced by industrialized nations. Bush said he feared the treaty's restrictions would hurt the U.S. economy.