The U.S. Supreme Court agreed Monday to hear a case on whether the Bush administration should be forced to regulate carbon dioxide to fight global warming.

The decision comes after a federal appeals court ruled against the plaintiffs, which consist of states, cities and environmental groups.

At issue is the responsibilities of the U.S. Environmental Protection Agency.

The group argues that under the U.S. Clean Air Act, the EPA must enforce tighter standards on motor vehicles to limit carbon dioxide emissions. Many scientists say there is growing evidence that carbon dioxide is trapping the earth's heat and contributing to global warming.

In their appeal of the federal court ruling, the group argued that the case "goes to the heart of the EPA's statutory responsibilities to deal with the most pressing environmental problem of our time."

But Washington says the EPA has discretion over whether to regulate carbon dioxide emissions. The administration also argues that carbon dioxide is not a pollutant under the federal clean air law.

It says the EPA should not be required to "embark on the extraordinarily complex and scientifically uncertain task of addressing the global issue of greenhouse gas emissions."

Instead, the administration argues there are voluntary ways to address climate change.

The lawsuit was prompted after the EPA's top lawyer concluded in 2003 that the agency did not have the authority to regulate carbon dioxide under the Clean Air Act. This reversed a legal opinion issued by the Clinton administration.

The plaintiffs include the states of California, Connecticut, Illinois, Maine, Massachusetts, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont and Washington.

A number of cities and environmental groups are also part of the lawsuit. They include Baltimore, New York City and Washington D.C., the Pacific island of America Samoa, the Union of Concerned Scientists, Greenpeace and Friends of the Earth.