The gradual reduction of HFCs is scheduled to start in 2019 for countries like the United States, with China and 100 others pledging to take action in 2024, followed by other countries including India and Pakistan in 2028. While countries including the US had reportedly pushed for a faster schedule, scientists cited by the Natural Resources Defense Council said it will avoid "early 90 percent of the temperature increase that HFCs could have caused." In a statement, director David Doniger said the group's estimates show this agreement "will avoid the equivalent of more than 80 billion tons of CO₂ over the next 35 years."
HFCs were introduced in the 80s as a replacement for those ozone-depleting chemicals, but while they're said to represent a small fraction of the greenhouse gases in the atmosphere, they trap heat and do more to warm the climate than carbon dioxide. They're used in refrigerators, air conditioners, insulating foams, inhalers and other applications, and will be replaced by more climate-friendly chemicals. The new agreement could avoid up to half of a degree of global warming by the end of the century, which will help reach the Paris Agreement goal of limiting warming to under two degrees.