# Montreal Protocol The Montreal Protocol on Substances that Deplete the Ozone Layer, adopted in 1987 under the 1985 Vienna Convention, phased out chlorofluorocarbons and other ozone-depleting substances. It has **198 parties — universal ratification**, the only UN treaty ever to achieve it, and it is routinely described as the most successful environmental agreement in history. The United States ratified it in 1988 under [[Ronald Reagan]], with Senate consent by a vote of 83–0. That fact deserves emphasis in this vault. A Republican administration negotiated and a Republican-era Senate unanimously ratified a binding international treaty that imposed costs on American industry, on the strength of atmospheric science, over the objections of affected manufacturers, in the same decade the [[Genocide Convention]] was being loaded with sovereignty reservations. ## Why It Worked The Protocol's design is the standard answer to why environmental treaties usually fail. **Targeted scope** — a specific, identifiable class of chemicals, not an economy-wide emissions target. **Substitutes existed**, or could be developed, so compliance was a transition rather than a sacrifice. **Trade measures** restricted commerce in controlled substances with non-parties, making membership more attractive than defection. And a **Multilateral Fund** paid developing countries' incremental compliance costs — the United States has supplied roughly a quarter of all its money since 1991. Crucially, the Protocol **adjusts and amends**. It has been strengthened repeatedly as the science advanced — London, Copenhagen, Montreal, Beijing — each ratified by 197 of 198 parties. ## Kigali The **Kigali Amendment**, in force since 1 January 2019, extends the Protocol to hydrofluorocarbons — the refrigerants adopted *as substitutes* for CFCs, which do not harm ozone but are potent greenhouse gases. **Over 160 parties**, per figures the Ozone Secretariat last updated in October 2024. **The US Senate gave advice and consent on 21 September 2022, by 69–27** — a bipartisan ratification of a climate-relevant treaty amendment, three years before the withdrawal sequence this vault documents. Implementation runs through the AIM Act. > [!note] Not verified > The exact deposit date and US entry-into-force date for Kigali were not confirmed from a primary source. The Senate vote is solid. ## The 2025–2026 Pressure The Protocol is **not** on the [[2026 International Organizations Withdrawal Memorandum]] list. What has happened is domestic and financial. **Funding.** The July 2025 rescissions package included **$437 million in aggregate treaty rescissions** across UN environmental treaties. Sources note the package does not itemize the Montreal Protocol share but would likely zero out US contributions to the Multilateral Fund. > [!warning] Not itemized > The $437M aggregate is confirmed; the Montreal Protocol-specific amount is not broken out in any source I could reach. Do not state a Montreal-specific figure. **Implementation.** EPA proposed loosening AIM Act requirements in October 2025 and **finalized amendments on 26 May 2026** — extending supermarket-refrigeration and cold-storage compliance deadlines to 1 January 2032, raising interim GWP limits, and removing an installation deadline for legacy residential air conditioning. EPA states the rule **"does not alter the ultimate GWP limits"** — it extends timelines rather than repealing the phasedown. Projected industry savings exceed $900 million. ## The Ozone Layer Is Recovering The **2025 Antarctic ozone hole was the fifth smallest since 1992**, the smallest in five years, and closed on 1 December 2025 — the earliest closure since 2019. Antarctic stratospheric ozone-depleting substances are down roughly a third since 2000. Projected recovery to 1980 levels: **around 2040 globally, 2045 in the Arctic, 2066 over Antarctica.** The next Scientific Assessment of Ozone Depletion is due at the end of 2026. ## Why It Matters Here The Montreal Protocol is the proof of concept, and it belongs in this cluster precisely because it is the exception. Every argument made against multilateral environmental agreements — that they surrender sovereignty, burden industry, exempt competitors, and rest on contested science — was made against this one in the 1980s, by the same coalitions, in the same terms. It was ratified unanimously, worked, and produced a measurable recovery of a physical system. That establishes something the rest of this vault's treaty layer cannot: **the failures documented elsewhere are not proof that international cooperation is impossible.** They are evidence about which conditions produce cooperation and which do not. The [[Chemical Weapons Convention]] page reaches the same conclusion from arms control — verification plus low strategic cost — and the pairing is the honest counterweight to the withdrawal sequence. The 2026 treatment is also instructive for being **so much gentler** than what the [[UN Framework Convention on Climate Change]] received. Same administration, same month, same subject area. One treaty got a withdrawal notification; the other got extended compliance deadlines and an unitemized funding cut. The difference is that Montreal has universal ratification, bipartisan Senate consent twice, an industry that has already retooled, and a demonstrable result — which turns out to be a considerable amount of protection. ## See Also - [[UN Framework Convention on Climate Change]] — the climate treaty being exited - [[Kyoto Protocol]] — the binding-targets model that failed in the Senate - [[Paris Agreement]] — the successor design - [[Chemical Weapons Convention]] — the arms-control treaty that also works, for related reasons - [[International Law Hub]] - [[Atmospheric Chemistry]] — the science behind air-quality regulation, from the ozone hole to acid rain