Supreme emissions

AMERICA’S bold effort to cut carbon-dioxide emissions from power plants is on hold. On February 9th the Supreme Court, divided five to four along partisan lines, putting the brakes on Barack Obama’s flagship environmental policy, pending a possible ruling this summer. The plan forms the core of America’s recent commitments to cut emissions, made at the UN climate talks in Paris.

Power plants are America’s largest source of greenhouse gases, accounting for just under a third of all emissions. The Clean Power Plan, under the authority of the Environmental Protection Agency (EPA), gives orders to each state which, considered together, should amount to removing 870m tonnes of carbon dioxide from power-station emissions by 2030 (as measured against 2005 levels). The regulations give states some flexibility over how and when to cut emissions. But each one is required to submit plans by 2018 and to show some progress on them by 2022. If the goals are met, the reduction by 2030 will be equivalent to taking 80m cars off the road.

The legal basis for the regulation was thought to lie in a ruling by the Supreme Court in 2007, which declared CO₂ a pollutant, thereby placing it under the EPA’s remit. The court upheld most of an agency rule requiring new or rebuilt factories and power plants to use the “best available technology” to limit their emissions of greenhouse gases in 2014. That year the justices also supported the EPA’s regulation of pollution that drifts over state lines. But the agency was rebuked for its overreach in 2015: the Supreme Court reprimanded it for regulating mercury, arsenic and other substances emitted by power plants without taking proper account of the costs. The Court’s new order suggests it may eventually conclude that the president has again exceeded his authority.

States, utilities and mining companies have declared the plan to be too much, too soon. The attorney-general of West Virginia, one of the states opposing it, said he was “thrilled” after the court issued its stay. Richard Lazarus, from Harvard Law School, calls the intervention “extraordinary”. Although compliance with the regulation is not required until 2022, the deadline for submitting first plans to cut back on emissions was supposed to be September. (States also had the option then to ask for more time.) That date will now almost certainly need to be pushed back.