It turns out that changing how we use and dispose of refrigerants — the chemicals used in refrigerators and air-conditioners — has the potential to reduce greenhouse gases more than any of the other 99 strategies in the book. When these chemicals leak or are improperly disposed, they are thousands of times more potent than carbon dioxide in warming the atmosphere. The 2016 Kigali Accord, signed by 160 countries, could reduce the emissions from refrigerants by 87 percent.