The ozone layer keeps healing, and 2025's hole was among the smallest in decades

The ozone hole over Antarctica is the rare environmental story with a beginning, a middle and a credible ending. In 2025 the hole was the fifth smallest since 1992, averaging about 18.7 million square kilometres at its seasonal peak, roughly 30% below the record 2006 hole, and it closed on 1 December, the earliest it has sealed over since 2019. The World Meteorological Organization says the long recovery is on track.

How we know

The reason is a 1987 agreement. The Montreal Protocol phased out CFCs and related chemicals that were tearing the ozone layer apart, and the atmosphere has been slowly clearing them since. Ozone-depleting substances over Antarctica have fallen about a third of the way back from their peak around 2000 toward pre-ozone-hole levels. The hole is tracked every year by NASA and NOAA satellites and balloon soundings, reported through the WMO, so its size is not a matter of opinion, and the 2025 reading fits a line that has been bending the right way for two decades.

Why it matters

The honesty here is about time and patience. A single small year is partly down to stratospheric weather, and the hole still varies from year to year with atmospheric dynamics. Full recovery to 1980 levels is not expected over Antarctica until around 2066, a date most people reading this will live to see, but not soon. The lesson is not that the job is done: when the world agrees to fix something, it can, even when the fixing takes generations.