The 1987 Montreal Protocol, an international treaty designed to protect the ozone layer by banning chlorofluorocarbons (CFCs), has also slowed global warming since the mid-1990s, a new analysis has found. The ban has lowered global temperatures by about 0.2 degrees F since it was enacted, scientists report in the journal Nature Geoscience. Researchers say that’s a significant decline considering the planet has warmed by an average of 1.6 degrees F since 1900. CFCs, a class of refrigerants banned because of their ozone-depleting qualities, are also powerful greenhouse gases, with warming potentials many thousands of times higher than CO2. A widely used replacement for CFCs — hydrofluorocarbons, or HFCs — are less powerful greenhouse gases, but negotiations are underway to amend the Montreal Protocol to apply to HFCs as well. The study’s lead author, Francisco Estrada of the National Autonomous University of Mexico, told Climate Central that by “pure luck” the Montreal Protocol has effectively slowed global warming, even more so than the Kyoto Protocol, which was was directly aimed at reducing greenhouse gas emissions.