16 September 1987 CE · treaty signed; recovery remains in progress · Global · Science

Montreal Protocol and ozone recovery

Countries signed the Montreal Protocol on 16 September 1987 to control the production and consumption of ozone-depleting substances; it entered into force in 1989 and was strengthened through later adjustments and amendments.

Atlas dossier · Cold War & Decolonization

Free device narration · synchronized English captions · transcript available

Why it matters

Monitoring, finance, technology change and differentiated schedules made ozone recovery possible, but recovery is not complete. The 2016 Kigali Amendment phases down climate-warming HFCs, which generally replaced ozone-depleting chemicals but do not themselves destroy ozone.

Date: 16 September 1987 CE · treaty signed; recovery remains in progress
Historical setting: Cold War & Decolonization · Global
People & communities: Atmospheric scientists · negotiators · refrigeration workers · manufacturers · monitoring agencies

Science, treaty and implementation were stages

Measurements and atmospheric chemistry connected chlorofluorocarbons to stratospheric ozone loss before countries signed the Montreal Protocol on 16 September 1987. The treaty entered into force in 1989 and was strengthened through later controls, funding, trade provisions and national implementation.

UN Environment Programme: Montreal Protocol ↗

Recovery is measured, not assumed

Satellite, balloon and ground observations track ozone, temperatures and relevant chemicals. Declines in controlled substances support projected recovery, but annual Antarctic ozone holes vary and the ozone layer is not already restored everywhere. Recovery language should retain timescales and uncertainty.

NASA Ozone Watch ↗

Kigali addresses climate through a related regime

Many HFCs replaced ozone-depleting substances and generally do not destroy stratospheric ozone, but they are powerful greenhouse gases. The 2016 Kigali Amendment added an HFC phase-down to the Montreal regime. That connection does not make ozone depletion and climate change the same atmospheric problem.

UNEP Ozone Secretariat: Kigali Amendment ↗

Illustrated sequence

A visual presentation accompanying this entry. Read each image’s attribution to distinguish archival records, later depictions and reconstructions.

IMAGE 1

Visual record

A NOAA satellite map of Antarctic ozone on 15 October 1987. This single observation is not a time series of ozone recovery.

Ozone Hole, 1987 (50700749751).jpg — NOAASatellites; Public domain; via NOAA Satellite archive / Wikimedia Commons. Resized, cropped and converted to WebP for Atlas display.

Source and reuse terms ↗

Interpretation note

Evidence, memory and historical debate

This dossier distinguishes the event’s basic chronology from later arguments about meaning, responsibility and legacy. When comparing religious, national, Indigenous or scholarly interpretations, consult the primary and institutional sources above alongside peer-reviewed historical work.

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