The Montreal Protocol Reducing Arctic Melting

(Washington Post articles are pay-walled)

The Montreal Protocol, with a mere 46 signatories in 1987, has reduced chlorofluorocarbon (CFC) use to 10% of peak 1974 levels. CFCs, typically used as refrigerant, are powerful greenhouse gases that degrade the Earth's ozone layer as they break down, allowing harmful UV radiation to reach the surface. A United Nations study estimates that the ozone layer will be restored to pre-industrial levels over most populated areas by 2040, with polar regions to follow in the coming decades.

It is also estimated that had CFC use continued, global temperatures would now be an additional 1 degree Celsius warmer.