The Montreal Protocol has been amended six times, and the Kigali Amendment added a phase-down of hydrofluorocarbons
Background
The Montreal Protocol on Substances that Deplete the Ozone Layer is a global agreement to protect the ozone layer by phasing out the chemicals that deplete it.
The phase-out plan covers both the production and the consumption of ozone-depleting substances.
The agreement was signed in 1987 and entered into force in 1989.
The parties meet once a year to take decisions on implementation, including adjusting or amending the Protocol, which has been done six times.
The most recent amendment is the Kigali Amendment, which called for the phase-down of hydrofluorocarbons in 2016.
HFCs had come in as replacements for ozone-depleting substances eliminated by the original Protocol; they do not deplete the ozone layer but are powerful greenhouse gases.
In plain words
HFCs Hydrofluorocarbons — Gases used in place of ozone-depleting substances that do not harm the ozone layer but warm the climate strongly.
Kigali Amendment Kigali Amendment to the Montreal Protocol — The amendment that brought hydrofluorocarbons under the Protocol for a phase-down.