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Ecology

Montreal Protocol on Substances that Deplete the Ozone Layer

The ozone treaty that actually cut ODS production and trade. Kigali later added HFCs for climate: still Montreal machinery, not a second UNFCCC.

NASA visualization of low ozone over Antarctica: the ozone hole the Montreal Protocol was written to reverse
Image: NASA Scientific Visualization Studio ( Public domain )
Ecology Existing / enacted Parties to the Montreal Protocol (UNEP Ozone Secretariat)

Official name: Montreal Protocol on Substances that Deplete the Ozone Layer
Citation: Montreal Protocol (1987, as adjusted/amended); Kigali Amendment adopted 15 October 2016, HFC controls in force from 1 January 2019 for Parties for which it entered into force
Year / status: Protocol adopted 1987. Kigali Amendment adopted 15 October 2016; HFC controls in force from 1 January 2019 for Parties for which it entered into force.

What it does

Controls production and consumption of ozone-depleting substances through binding schedules, trade controls with non-Parties, reporting, and a Multilateral Fund for Article 5 Parties. Adjustments and amendments tighten annex chemicals over time. The Kigali Amendment (2016) phases down hydrofluorocarbons (HFCs): potent greenhouse gases used as ODS substitutes: under the same Protocol.

Where it applies / status

Near-universal Protocol membership (Ozone Secretariat / depositary). Protocol adopted 1987; successive adjustments and amendments. Kigali entered into force 1 January 2019 once ratification thresholds were met; HFC trade-control provisions have a separate later trigger. Treat party status for Kigali as depositary-specific.

Documented benefits or intended effects

Ozone-layer recovery metrics and ODS phase-out schedules are the Protocol’s documented success track: use Ozone Secretariat / WMO-UNEP scientific assessments, not marketing. Kigali’s intended climate benefit is avoided HFC warming; delivery follows national phase-down schedules.

Caveats

Success on ODS is not automatic success on every climate gas. HFCs are under Montreal via Kigali; CO₂ and methane stay under UNFCCC/Paris. Illegal trade and exemptions still matter. Do not caption this card as “the climate treaty”: that is Paris.

Sources

Ozone Secretariat Montreal Protocol page; Ozone Secretariat amendments page (including Kigali); UN Treaty Depositary record for the Kigali Amendment.