Twelve states and several prominent environmental groups are suing the Environmental Protection Agency over a ruling it made last year that said it doesn’t have the authority to control greenhouse gas emissions under the Clean Air Act.

The states – California, Connecticut, Illinois, Maine, Massachusetts, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, and Washington, along with the cities of Baltimore, New York, and the District of Columbia – also want more regulatory control of emissions such as oxides of nitrogen and particulate matter as part of an effort to stop global warming.

The Sierra Club, which supports the lawsuit, said such emissions have caused the world to ‘warm up,’ leading to unstable weather patterns, floods, droughts, and outbreaks of tropical diseases. Extreme weather events cost Americans nearly $20 billion in 2002, a cost that could increase if the U.S. does nothing to curb global warming, the group said.

Allen Schaeffer, executive director of the Diesel Forum, told Fleet Owner that the lawsuit by the states against EPA represents a step in their continuing strategy to wrest emission regulatory control away from the federal government. The eventual impact on trucking from this effort, however, remains unclear.

“Global warming is an issue larger than trucking and transportation,” Schaeffer said. “Transportation is really only 25% of the issue. On-road diesel emissions in the United States, for example, only account for 0.7% of the world’s ‘black carbon’ pollution. So there is still plenty of uncertainty on both the political and scientific levels as to how much of a contributor transportation is to the global warming issue.”