A federal appeals court ruled against an Obama-era regulation on Tuesday that would have prohibited the use of refrigerants known as hydrofluorocarbons (HFCs), which are also potent greenhouse gases, Bloomberg reports.
The law, which was signed in 2015, relied on a statute allowing the Environmental Protection Agency to regulate ozone-depleting substances. The problem, the court ruled, is that HFCs don't harm the ozone layer; they were, in fact, designed to replace another class of chemical refrigerants, called chlorofluorocarbons, that did harm the ozone layer. But HFCs, used in refrigerators and air conditioners, are the world's fastest-growing greenhouse gas. In 2016, more than 170 nations around the globe—including the United States—agreed to the Montreal Protocol's Kigali Amendment, which would limit the use of HFCs and could prevent up to 0.5 degrees Celsius of global warming by the end of the century.
Even the Trump administration, which has attempted to dismantle dozens of Obama-era climate regulations since Donald Trump took office in January, supported the rule, which would have ensured American companies remained competitive.