Montreal Protocol is recorded in this encyclopedia from the source named below.
Overview
The Montreal Protocol, officially the Montreal Protocol on Substances That Deplete the Ozone Layer, is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and was entered into force on 1 January 1989. Since then, it has undergone several amendments and adjustments, with revisions agreed to in 1990 (London), 1992 (Copenhagen), 1995 (Vienna), 1997 (Montreal), 1999 (Beijing), 2007 (Montreal), 2016 (Kigali) and 2018 (Quito). The Montreal Protocol has been ratified by 198 parties (197 states and the European Union), making it the first universally ratified treaty in United Nations history. Due to its widespread adoption and implementation, it has been hailed as an example of successful international co-operation. Former United Nations (UN) secretary-general Kofi Annan stated that it is "perhaps the single most successful international agreement to date has been the Montreal Protocol". As a result of the Protocol, the ozone hole over Antarctica is slowly recovering. Climate projections indicate that the ozone layer will return to 1980 levels between 2040 across much of the world and 2066 over Antarctica.
Source and reuse
The descriptive text above is drawn from the English-language encyclopedia article Montreal Protocol, reused under the Creative Commons Attribution-ShareAlike licence and attributed in the sources block on this page. Figures in the infobox come from Wikidata and carry that project's own provenance; they should be checked against the cited source before being relied on.
Editorial note
This record is a sourced summary, not original research. Where the underlying material is silent on a point, this article is silent too. Last reviewed 2026-09-23.