The recovery of Earth's ozone layer is one of the biggest environmental success stories in modern history.
Scientists estimate that, if countries continue following current international agreements, ozone levels will return to their 1980 values around 2040 across most of the world, 2045 over the Arctic and 2066 over Antarctica.
The breakthrough began with the Montreal Protocol, an international agreement signed in 1987.
Countries committed to phasing out chemicals called chlorofluorocarbons (CFCs), commonly used in refrigerators, air conditioners and aerosol products.
These chemicals release chlorine and bromine in the atmosphere, which destroy ozone molecules.
The recovery is not perfectly smooth. Weather conditions can make the Antarctic ozone hole larger in some years.
In 2026, it became the seventh largest recorded, despite the long-term improvement.
