ENVIRONMENT

The Hole We Repaired

1985 CE

History · Contemporary · Holocene · Meghalayan

In 1985, British scientists announced that springtime ozone over Antarctica was collapsing: a hole in the layer that shields life from ultraviolet light, opened by chlorofluorocarbons from spray cans and refrigerators. Two years later the Montreal Protocol began phasing the chemicals out, and in time every country on Earth signed it. By 2016, measurement and modelling agreed that the Antarctic ozone layer had begun to heal in the month of September, humanity's first deliberate repair of a planetary system.

Why it matters

The ozone hole is the proof, cited in climate negotiations ever since, that global environmental action can work: a planetary threat found by patient monitoring, attributed by chemistry, and answered by treaty within two years of its discovery, even if the recovery took decades to show. It is also a lesson in luck: had industry chosen bromine instead of chlorine, the damage would have been far worse before anyone thought to look. The sky can be broken, and mended.

Dating & uncertainty

The British Antarctic Survey reported the springtime collapse of Antarctic ozone in 1985, from ground measurements begun decades earlier; the Montreal Protocol followed in 1987 and phased out chlorofluorocarbons worldwide. By 2016, September measurements and models agreed that healing had begun, fingerprinted in the ozone column, in the vertical profile and in the area of the hole, with volcanic eruptions setting it back along the way.

Sources

1. Farman, Gardiner & Shanklin (1985), Nature · Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interactiondoi:10.1038/315207a0
2. Solomon et al. (2016), Science · Emergence of healing in the Antarctic ozone layerdoi:10.1126/science.aae0061
3. United Nations Environment Programme · The Montreal Protocol on Substances that Deplete the Ozone Layer. Institutional source: UNEP Ozone Secretariat, accessed 2026-08-30.

Our species’ history as one day

23:59:4811.2 s before midnight

if the 315,000 years of Homo sapiens were compressed into a single day