From Ozone Depletion to Global Warming: The Kigali Amendment

The Montreal Protocol was one of the most successful treaties ever signed. Ratified by 197 countries and the European Union in 1987, it went into effect in 1989, limiting the use of chemicals that destroy the ozone layer that protects Earth from harmful ultraviolet radiation.

Under the treaty, nations began phasing out the use of substances with high ozone depletion potentials (ODPs), primarily chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that are used in the building industry as refrigerants and foam insulation blowing agents. CFCs have the highest ODP and were banned in the U.S. in 1996. HCFCs have lower ODP and are being phased out over time, with 99.5% scheduled to be removed from the market by 2020 and 100% by 2030. These phaseouts are expected to bring the levels of ODP back to 1980 levels as soon as 2050.