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Court tells Bush to cool it

The slow process of getting the United States to deal seriously with global warming came alive last fall when voters unseate d Republican committee chairmen in Congress who considered climate change a hoax or a threat to the petroleum industry. Yesterday's Supreme Court decision pushed the federal government even closer to action by stripping the Environmental Protection Agency of its nonsensical claim that it could not curb the most common greenhouse gas, carbon dioxide, because it is not a pollutant.

Massachusetts led a group of 12 states and several environmental organizations in a successful effort to stop the EPA from arguing that it was powerless to regulate motor vehicles, which are responsible for about one-third of all carbon dioxide emissions. By finding that this gas is a pollutant as defined by the Clean Air Act, the court's 5-4 majority also opened the door for regulation of emissions from electric utilities and manufacturers.

In his majority decision, Justice John Paul Stevens placed the onus on the EPA to either begin regulation of carbon dioxide in cars or make a strong case for why it should not. "EPA has offered no reasonable explanation for its refusal to decide whether greenhouse gases cause or contribute to climate change," Stevens wrote. The Clean Air Act authorizes the EPA to regulate pollutants that can "endanger public health or welfare" and defines "welfare" to include adverse effects on "weather" and "climate."

President Bush pledged during the 2000 campaign to regulate carbon dioxide but then reversed himself once in office under pressure from the energy and auto industries. Yesterday's embarrassment should cause Bush to honor that pledge and direct his EPA to curb vehicles' carbon dioxide emissions. However, the most immediate effect of yesterday's ruling might be to strengthen the authority California has claimed to insist on strict emission limits in cars sold there. Ten other states, including Massachusetts, plan to adopt the same standards. Since there is no practical system for capturing carbon dioxide in cars' exhaust, the emission limits would in effect force auto makers to improve their vehicles' efficiency, which the industry has resisted.

The prospect of California and the other states adopting rigorous new rules on efficiency is undoubtedly one reason that the auto industry responded to yesterday's ruling by calling for an approach to combatting global warming that would be nationwide and involve all industries, not just autos. In fact, it will take action by all sectors of the economy to reduce substantially greenhouse gas emissions by the United States, which now produces 22 percent of the global total. But yesterday's ruling should help to ensure that future federal rules on vehicles' carbon dioxide emissions approach California's proposed regulations in their toughness.