On October 15, 2016, representatives from 170 countries concluded negotiations in Kigali, Rwanda that resulted in a legally binding accord to limit hydrofluorocarbons (HFCs) in an effort to combat climate change. HFCs are chemical coolants used in air conditioners and refrigerants. Chemical companies developed HFCs in the late 1980s after the Montreal Protocol banned ozone-depleting coolants called chlorofluorocarbons (CFCs). HFCs do not harm the ozone layer, but they have 1,000 times the heat trapping potential of carbon dioxide.

The Kigali accord is an amendment to the 1987 Montreal Protocol (which was ratified by the U.S. Senate during the Regan Administration). Thus, the Kigali accord has the legal force of a treaty without further ratification by the current U.S. Senate. Although HFCs make up a small percentage of greenhouse gasses in the atmosphere, because of their extremely high warming potential, the reductions called for in the Kigali accord will lead to the reduction of the equivalent of 70 billion tons of carbon dioxide, which is approximately two times the amount of carbon dioxide emitted globally each year.

The Kigali agreement contains three tracks for HFC reductions, determined by a county’s wealth and need for air conditioning. The richest countries, including the United States and those in the European Union, are in the first track. Those countries will freeze the production and consumption of HFCs by 2018, reducing them to 15 percent of 2012 levels by 2036. The second track contains most of the rest of the world, including China, Brazil and all of Africa. Second track countries will freeze HFC use by 2024, reducing it to 20 percent of 2021 levels by 2045. Finally, the third track contains a small group of the world’s hottest countries — India, Pakistan, Iran, Saudi Arabia and Kuwait. Those countries will not have to freeze HFC use until 2028, and will have to reduce it to 15 percent of 2025 levels by 2047.

Secretary of State John Kerry participated in the negotiations in Kigali, along with EPA Administrator Gina McCarthy. Secretary Kerry praised the final outcome, stating that “It is likely the single most important step we could take at this moment to limit the warming of our planet and limit the warming for generations to come.”