One of the reasons that make the recently-concluded climate conference in Kigali, Rwanda, notable is that 197 countries came together and signed the first legally-binding climate treaty of the 21st century. At the 28th Meeting of Parties of the Montreal Protocol, countries agreed to adopt an amendment of the Protocol to phase down the use of hydrofluorocarbons (HFCs).

HFCs are refrigerants used in air conditioning and refrigeration systems. They are potent greenhouse gases with global warming potential (GWP) thousand times more than carbon dioxide (CO2). The Montreal Protocol was signed in the early 1990s to eliminate the use of chemicals that caused the ozone-hole. However, the replacement for the ozone-depleting chemicals was HFCs, which caused global warming. At the Kigali meeting, the world agreed to reduce the use of HFCs and move to refrigerants that neither cause global warming nor create an ozone-hole.