nature & planetOur World in Data1980s–1990s · Antarctica
The Antarctic ozone hole stopped growing in the late 1990s after the world phased out CFCs
The ozone hole over Antarctica grew rapidly through the 1980s and early 1990s, peaking at more than 25 million square kilometres, slightly larger than Sub-Saharan Africa. Ozone high in the atmosphere absorbs harmful ultraviolet radiation. Chlorine from chlorofluorocarbons, once common in aerosols and refrigerants, destroys ozone, and the cold, dark Antarctic winter creates clouds that speed up the chemistry. After the 1987 Montreal Protocol phased out these chemicals, the hole stopped expanding in the late 1990s and has since begun slowly recovering.
In the frigid Antarctic stratosphere, special clouds form that release chlorine from reservoir compounds into reactive forms. When sunlight returns in spring, these reactive chlorine atoms break apart ozone molecules in a chain reaction, thinning the ozone layer over the continent.
The ozone story is widely seen as a rare success in international environmental cooperation: scientists identified a problem, governments acted, and the damage began to reverse. It shows that global treaties can work when the cause is clear and substitutes exist.
Ozone depletion followed the pattern of other environmental problems in which a hidden chemical caused harm and a cooperative treaty later reversed the trend, a precedent often cited in climate policy debates.
The Montreal Protocol is the first UN treaty to achieve universal ratification.
background
Ozone depletion in the stratosphere (the ozone layer) consists of two related phenomena observed since the late 1970s: a lowered total amount of ozone in Earth's upper stratosphere, and a much larger springtime decrease in around Earth's polar regions. The latter phenomenon over the south pole is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events.
From Wikipedia: Ozone depletion (CC BY-SA 4.0) ↗
