On Monday, the Supreme Court ruled that the Environmental Protection Agency has the authority to regulate greenhouse gas emissions from automobiles under the Clean Air Act. Stating that gases, which contribute to man-made climate change, unequivocally qualify as air pollutants, the court also told the EPA that the agency must come up with a more convincing, scientifically based explanation than it has heretofore provided if it continues to do nothing.


It was a momentous decision — the first time the nation’s highest court has addressed the threat of global warming. But momentous is just one word to describe the decision in Massachusetts v. EPA. Other journalists chose to be more precise about how the case will guide future events. It “shredded the underpinnings of other lawsuits” trying to block the regulation of heat-trapping gases, wrote Felicity Barringer in a New York Times news analysis Tuesday. It “cleared the way … for a more aggressive attack by government on global warming,” wrote David G. Savage in a front-page piece in the Los Angeles Times.


Well, maybe, but the reality of what this decision does and doesn’t do is far more complicated and less certain. It will now be up to journalists to start filling in the picture. Barringer and Savage were in no sense being Pollyannaish; their stories were well thought out and reflected the nuances of this ruling. But it will take a lot more ink before reporters can say for certain that this “strong rebuke” (as many papers called it) of the Bush administration’s climate intransigence has produced tangible results.


Here, then, is a look at some of the many and varied questions raised by Monday’s ruling.


The California Battleground. In 2002, the state passed a law requiring cars to emit less carbon dioxide beginning in 2009. Last year, Governor Arnold Schwarzenegger signed another law requiring a 25 percent reduction in the state’s carbon dioxide emissions by 2020. Many experts think Monday’s Supreme Court ruling will help California’s cause, but, in a good news analysis Tuesday in the L.A. Times, Janet Wilson and Tim Reiterman point out that there is still a two-pronged threat. First, even if the EPA decides to regulate greenhouse gases at the federal level (which is not a foregone conclusion), the state must still obtain a waiver from the agency to validate its own standards because the Clean Air Act generally prohibits states from dictating fuel efficiency for automobiles. Second, California faces a challenge from the automobile industry, which is suing on the grounds the state is preempting national Corporate Average Fuel Economy (CAFE) standards and inhibiting the president’s authority to guide foreign policy (the idea being that climate change is a global threat that can only be addressed on the global level). California is a key state in the emissions debate. It is the only one in the country that has the right to obtain a waiver to enact state-level fuel efficiency standards under the Clean Air Act, but if it is allowed to do so, other states may also adopt those standards.


Litigation Tsunami. A front-page New York Times article on Wednesday quoted one expert saying that there are at least 300 bills in forty states that address greenhouse gases and climate change in one form or another. In 2003, the Financial Times predicted that climate change would be the successor to tobacco in terms of the overwhelming amount of anticipated litigation. There are more than a dozen global-warming cases already on court dockets around the country, according to Justin R. Pidot, a fellow at the Georgetown Environmental Law & Policy Institute who recently authored a study on the current state of litigation and legal issues surrounding climate. Another case, one that challenges the EPA’s refusal to regulate carbon dioxide emissions from power plants — the country’s largest source of man-made greenhouse gases — had been stalled in the federal appeals court for the District of Columbia, pending Monday’s decision.

Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.