By David Doniger and Alex Hillbrand
This is a big year for the Montreal Protocol—the 30th anniversary of the world's most successful environmental protection agreement.
Every country on Earth is a party to this treaty, which has prevented catastrophic destruction of the ozone layer that protects us from the sun's dangerous ultraviolet radiation. Phasing out ozone-destroying chemicals has also provided a huge climate protection side-benefit, because many of those chemicals are also powerful heat-trapping agents. Countries took climate protection a step farther by adopting the Kigali Amendment to phase down hydrofluorocarbons (HFCs) in October 2016.