The U.S. Supreme Court, tackling its first case on climate change, appeared divided and somewhat baffled Wednesday over how the government should respond to the warming of the planet.

Justice Antonin Scalia, reflecting the skeptic's view, pressed the lawyer representing Massachusetts and other states about how soon the dire effects of global warming would begin. "When is the predicted cataclysm?" Scalia asked with some sarcasm.

Chief Justice John Roberts, echoing the Bush administration's view, wondered why the United States should reduce its greenhouse gas emissions if China's output of gases will rise sharply in coming years.

Justice Stephen Breyer suggested that a more active response by government could halt global warming.

"Suppose, for example, they regulate this, and before you know it, they start to sequester carbon with the power plants, and before you know it, they decide ethanol might be a good idea, and before you know it, they decide any one of 15 things, each of which has an impact, and lo and behold, Cape Cod is saved," Breyer said. "Now, why is it unreasonable?"

The clashing views gave just a hint of what the justices might decide in Massachusetts vs. Environmental Protection Agency, a case aimed at settling whether the federal government must regulate vehicle emissions of greenhouse gases under the Clean Air Act. The ruling, expected by July, also could determine whether California can proceed with its first-in-the-nation law restricting tailpipe emissions of greenhouse gases, which is set to take effect in 2009.

Regardless of the court's decision, Congress could soon limit emissions of carbon dioxide and other heat-trapping gases. Sen. Barbara Boxer, the incoming chair of the Environment and Public Works Committee, said she will begin hearings when Democrats take power in January on measures to curb greenhouse gases from vehicles, power plants and other sources.

"We have to go after carbon and reduce it wherever we find it, and the fact is about a third of the problem is from vehicles," Boxer said Wednesday.

She believes it's likely the high court will stake out a middle ground -- ruling that EPA has the authority to regulate greenhouse gases but that the agency is not required to do so. She added, "If the court were to say that the EPA cannot regulate carbon, then we clearly will have to fix the Clean Air Act."

The case is being watched closely in California. The U.S. Environmental Protection Agency has been sitting for a year on the state's request for a waiver to implement its vehicle emissions rules, even though Gov. Arnold Schwarzenegger has written President Bush several times asking him to approve it. If the high court rules against the states, it could give EPA the legal justification to deny California's request.

"It would be a blow to us," said Linda Adams, secretary of California's Environmental Protection Agency.

The case before the court is being pushed by 12 states, including California, one U.S. territory, three cities and 13 environmental groups that want to prod the Bush administration into regulating greenhouse gases.

In 2003, the federal EPA denied a petition by environmentalists to label four greenhouse gases -- carbon dioxide, methane, nitrous oxide and hydrofluorocarbons -- as air pollutants. The agency said Congress never intended to address climate change with the Clean Air Act.

The EPA also asserted that even if the agency had the authority to regulate greenhouse gases, it wouldn't because of scientific uncertainty around global warming and because limiting U.S. emissions could hurt the president's ability to persuade other countries to reduce their greenhouse gas output.

Massachusetts Assistant Attorney General James Milkey, arguing the case for the petitioning groups, told the justices that EPA's view was a clear misreading of the Clean Air Act, which he said requires the federal agency to regulate any pollutant that "may reasonably be anticipated to endanger public health or welfare." The act includes climate and weather in its definition of welfare.

Several justices on the court's liberal wing appeared sympathetic to his view. Justice Ruth Bader Ginsburg twice noted that the EPA, under former President Bill Clinton, had come to a different conclusion than it expresses now -- that the agency has the authority to regulate carbon dioxide.

Justice John Paul Stevens also took on the agency's assertions about scientific uncertainty on climate change, saying the EPA deliberately ignored key findings from a respected National Academy of Sciences report on global warming.

"In their selective quotations, they left out parts that indicated there was far less uncertainty than the agency purported to find," Stevens said.

Deputy Solicitor General Gregory Garre, who argued the case for the Bush administration, was left in the uncomfortable position of challenging the consensus among climate scientists that human activity is contributing to global warming.

"Is there uncertainty on the basic proposition that these greenhouse gases contribute to global warming?" Stevens asked.

"Your honor, the (National Academy of Sciences) report says that it is likely that there is a connection, but that it cannot unequivocally be established," Garre said.

However, the justices on the conservative wing of the court expressed sympathy with the administration's view. Justice Samuel Alito suggested EPA was right to propose that United States wait to cut emissions until other countries agreed to the same.

"What is wrong with their view that for the United States to proceed unilaterally would make things worse?" Alito said.

Roberts and Scalia pressed Milkey on whether the states could even prove they were injured by vehicle emissions in order to show legal standing in the case. Milkey responded: "The injury doesn't get any more particular than states losing 200 miles of coastline, both sovereign territory and property we actually own, to rising seas."

Court observers said the key swing vote will be Justice Anthony Kennedy. On Wednesday, he pointed out holes in both sides' arguments, making his opinion tough to gauge.

Boxer said she's betting that Kennedy will be the decisive vote in forcing the administration to take action on climate change.

"I don't think we should lose sight of the fact that Justice Kennedy is from California, and California has an ethic when it comes to the environment that cuts across party lines," Boxer said. "I have to believe he has that ethic. Let's put it this way, I'm praying he does."

The case is Massachusetts vs. EPA, 05-1120.

Science in the court

Justice Antonin Scalia, in a question and answer with Massachusetts Assistant Attorney General James Milkey, showed he hadn't yet seen Al Gore's documentary on global warming, "An Inconvenient Truth." Here is an excerpt from the official transcript of Wednesday's hearing as posted on the Supreme Court's Web site: www.supremecourtus.gov/oral_arguments/argument_transcripts/05-1120.pdf

Justice Scalia: "Mr. Milkey, I had -- my problem is precisely on the impermissible grounds. To be sure, carbon dioxide is a pollutant, and it can be an air pollutant. If we fill this room with carbon dioxide, it could be an air pollutant that endangers health. But I always thought an air pollutant was something different from a stratospheric pollutant, and your claim here is not that the pollution of what we normally call 'air' is endangering health. That isn't, that isn't -- your assertion is that after the pollutant leaves the air and goes up into the stratosphere it is contributing to global warming."

Mr. Milkey: "Respectfully, Your Honor, it is not the stratosphere. It's the troposphere.

Justice Scalia: "Troposphere, whatever. I told you before I'm not a scientist."

(Laughter.)

Justice Scalia: "That's why I don't want to have to deal with global warming, to tell you the truth."

The justices' views

Comments from several of the justices during Wednesday's oral arguments in the global warming case before the Supreme Court:

Chief Justice John Roberts:
"There's a difference between the scientific status of the harm from lead emissions from vehicles that - when you have lead in the gasoline, to the status, the status of scientific knowledge with respect to the impact on global warming today. Those are two very different levels of uncertainty."

Justice Antonin Scalia:
"Is it an air pollutant that endangers health? I think it has to endanger health by reason of polluting the air, and this does not endanger health by reason of polluting the air at all."

Justice John Paul Stevens:
"I find it interesting that the scientists who worked on that report said there were a good many omissions that would have indicated that there wasn't nearly the uncertainty that the agency described."

Justice David Souter:
"They don't have to show that it will stop global warming. Their point is that it will reduce the degree of global warming and likely reduce the degree of loss, if it is only by 2 1/2 percent. What's wrong with that?"

Justice Samuel Alito:
"And so the reduction that you could achieve under the best of circumstances with these regulations would be a small portion... would it not?"

Justice Ruth Bader Ginsburg:
"... how far will you get if all that's going to happen is it goes back and then EPA says our resources are constrained and we're not going to spend the money (to regulate greenhouse gases)?"

Justice Stephen Breyer:
"Now what is it in the law that says that somehow a person cannot go to an agency and say we want you to do your part? Would you be up here saying the same thing if we're trying to regulate child pornography and it turns out that anyone with a computer can get pornography elsewhere? I don't think so."

©2006 San Francisco Chronicle

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