One of the most powerful climate pollutants on earth, hydrofluorocarbons or HFCs, account for a small portion of U.S. climate pollution, but scientists say it’s important for countries to urgently cut them just because they’re so potent—and growing.
Efforts to cut HFCs became more difficult both in the U.S. and globally on Tuesday, when a federal appeals court in Washington, D.C., ruled that the Environmental Protection Agency has overstepped its authority in regulating HFCs under the Clean Air Act.
The ruling leaves the U.S. without an immediate legal mechanism to control HFCs, which amount to about 3 percent of U.S. climate pollution.
Though that’s a small part of the nation’s greenhouse gas emissions, they’re between about 1,000 to 12,000 times as potent as carbon dioxide, depending on the specific chemicals used to make HFCs.
That means that just one kilogram of an HFC is the equivalent of 1.7 tons of carbon dioxide pollution, said Paul Blowers, a chemical engineering professor at the University of Arizona.
HFCs lurk in the leaky refrigerator cases of grocery stores and air conditioners across the globe. Each of those refrigerator cases leaks about 10 percent of its HFCs each year. The EPA expects HFC pollution to triple in the U.S. in the coming decades, and it could grow dramatically here and abroad as more nations adopt air conditioning as the climate warms.
Blowers said HFC emissions are easier to cut than carbon emissions from vehicle tailpipes and other forms of climate pollution because it’s easier to regulate tens of thousands of grocery store refrigerator cases than hundreds of millions of cars on the road.
The ruling, by a three-judge panel, said the EPA was out of bounds when it approved a federal rule in 2015 requiring companies to replace HFCs with another gas as a way to cut America’s greenhouse gas emissions.
The ruling affects an international treaty signed by negotiators from the U.S. and 169 other nations in Kigali, Rwanda, last year to help phase out HFCs globally. The agreement, which must be ratified by the U.S. Senate, amended the 1987 Montreal Protocol to include a ban on HFCs globally. The Montreal Protocol is the international treaty banning chemicals that deplete the ozone layer.
Using the Clean Air Act to comply with the protocol, the EPA chose HFCs to replace ozone-depleting chlorofluorocarbons, or CFCs, in aerosol cans and refrigerators — the main cause of the ozone hole. Without…