Hydrochlorofluorocarbons (HCFCs), man-made chemicals refrigerants used in air conditioners and refrigeration systems, are potent greenhouse gases that also deplete atmospheric ozone. The chemicals were introduced in the 1980s as a replacement for chloroflourocarbons, CFCs, artificial chemicals that were even worse for the ozone layer and for the climate.
HCFCs are currently being phased out worldwide under a binding, international agreement known as the Montreal Protocol. Starting in 2020, the United States can no longer produce or import most HCFCs according to the agreement.
The chemicals are, however, still widely used in existing air conditioning and refrigeration systems. The most common HCFC, HCFC-22 is a climate “super-pollutant,” 1760 times more potent as a greenhouse gas than carbon dioxide.
Hydrofluorocarbons (HFCs), a chemical replacement for HCFCs, do not play a significant role in ozone depletion but are still highly potent greenhouse gases. HFC-134a, the chemical refrigerant that replaced HCFCs in cars, is 1300 times more effective at warming the atmosphere than carbon dioxide.
An amendment to the Montreal Protocol that was ratified in 2016 and took effect in 2019 will phase out HFC production in the coming years and drive the use of chemical refrigerants that are less harmful for the climate.
Known as the Kigali Amendment to the Montreal Protocol, the agreement could help avoid up to 0.5°C of additional warming by 2100, according to the Institute for Governance & Sustainable Development (IGSD)
The United States has yet to ratify the Kigali Amendment, but, unlike the Paris Climate Agreement, the Montreal Protocol and its amendments are binding, with sanctions for countries that do not ratify.
In 2033, refrigerants produced in a country that has failed to ratify the amendment could be barred from being exported to countries that have signed on. If the United States has not ratified by then, American chemical manufacturers estimate they would lose out on billions of dollars each year in potential exports.
The agreement’s binding requirements and near-universal membership—every UN member country has signed the Montreal Protocol and more than 100 have ratified the Kigali Amendment—have made it arguably the most effective international environmental treaty.
Without the Montreal Protocol, the use of CFCs and other ozone depleting chemicals could have had a climate impact as large as that from carbon dioxide, the largest contributor to climate change, a 2007 study published in the Proceedings of the National Academy of Sciences concluded.
“It’s astounding how successful it has been,” Durwood Zaelke, president of the Institute for Governance and Sustainable, said.