Supreme Court rules greenhouse gases a pollutant

In a defeat for the Bush administration, the US Supreme Court ruled Monday that greenhouse gases are a pollutant and ordered federal environmental officials to re-examine their refusal to limit emissions of the gases from cars and trucks.

The justices' 5-4 decision did not go as far as to require the US Environmental Protection Agency to regulate greenhouse gases, such as carbon dioxide. Rather, the court directed the agency to take a new look at the gases. If it determines they cause global warming and therefore human harm, the agency should regulate them under the federal Clean Air Act, or provide a reasonable explanation why it will not, the court said.

The case, brought by 12 states and 13 environmental groups and argued by the Massachusetts Attorney General's office, is the high court's first decision on global warming and is expected to have far-reaching implications for regulating greenhouse gases in the United States.

"In short, EPA has offered no reasoned explanation for its refusal to decide whether greenhouse gases cause or contribute to climate change," Justice John Paul Stevens wrote for the majority.

The EPA had argued that the Clean Air Act did not give it authority to regulate greenhouse gases in part because of "substantial scientific uncertainty" about its harm to human health and the environment.

The decision comes just two months after the US endorsed a statement by hundreds of scientists worldwide that concluded that there was a high degree of certainty that the recent rise in global temperatures was mostly caused by increasing levels of carbon dioxide and other heat-trapping gases in the atmosphere.

"Despite acknowledging that global warming poses serious dangers to our environment and health, the Bush Administration has done nothing to regulate greenhouse gas emissions," Massachusetts Attorney General Martha Coakley said in a statement. "As a result of today's landmark ruling, EPA can no longer hide behind the fiction that it lacks any regulatory authority to address the problem of global warming." The EPA released a statement saying it is reviewing the decision. "The Bush Administration has an unparalleled financial, international and domestic commitment to reducing greenhouse gas emissions," it said, adding that the administration is pursuing voluntary efforts to prevent emissions and has spent over $35 billion on climate change programs -- "more than any other country in the world." Stevens was joined in the majority by Justices Stephen Breyer, Ruth Bader Ginsburg, David Souter and Anthony Kennedy. Chief Justice John Roberts and Justices Samuel Alito, Antonin Scalia and Clarence Thomas dissented.

Roberts wrote that Congress and the executive branch, not the courts, should address the states' complaints about the EPA's lack of regulation.

He said his stance "involves no judgment on whether global warming exists, what causes it, or the extent of the problem."