Montreal Protocol Signed
The Montreal Protocol was signed, beginning the global effort to protect the ozone layer
September 16, 1987
The Treaty That Saved the Ozone Layer
The Montreal Protocol on Substances that Deplete the Ozone Layer was signed on September 16, 1987 in Montreal, Canada. It was a binding international agreement to phase out the production and use of chemicals known to destroy the ozone layer — primarily chlorofluorocarbons (CFCs) used in refrigerants, aerosols, and industrial processes. The treaty was the result of years of scientific research, diplomatic negotiation, and public pressure following the discovery of the Antarctic ozone hole in 1985.
How It Worked
The protocol set specific timetables for reducing and eventually eliminating ozone-depleting substances. Developed countries were required to act faster than developing nations, and a fund was established to help poorer countries find and adopt alternatives. The agreement has been strengthened multiple times through amendments. The 2016 Kigali Amendment extended it to cover hydrofluorocarbons (HFCs), powerful greenhouse gases that replaced CFCs but contributed to climate change.
A Model for Global Environmental Action
The Montreal Protocol is widely considered the most successful international environmental agreement in history. It has been ratified by every country in the world — the only UN treaty to achieve that distinction. Production of the most harmful ozone-depleting substances has fallen by over 99 percent. The ozone layer is recovering and is projected to return to healthy levels by mid-century. Scientists estimate the treaty has prevented millions of cases of skin cancer and cataracts. It also provided valuable lessons for crafting the climate agreements that followed. Check how many years since the treaty was signed.