The Montreal Protocol was signed on 16 September 1987 and came into force on 1 January 1989. It phases out CFCs, halons and HCFCs, the gases that thin the ozone layer. It is a protocol under a 1985 framework treaty on the ozone layer. It is the only UN treaty ratified by every country.
Key facts
- Signed 16 September 1987, in force 1 January 1989; 16 September is World Ozone Day.
- Ratified by 198 parties, the first UN treaty with universal ratification. (as of 23 Oct 2026)
- The substitutes that replaced ozone-depleting gases turned out to be powerful greenhouse gases; the Kigali Amendment phases them down.
- The Kigali Amendment was adopted on 15 October 2016 and came into force on 1 January 2019.
- India's phase-down under Kigali starts with a 10 percent cut in 2032. (as of 23 Oct 2026)
Why exams ask about it
Setters pair the treaty with its amendment, its parent convention, the gases each covers and India's phase-down dates.
Pakka yaad trick
Montreal (1987) targets ozone-eaters; Kigali (2016) targets heat-trappers. Older treaty, older problem.