What’s happening with the ozone hole over Antarctica?
New report puts the spotlight back on the layer that protects Earth from ultraviolet radiation.
For years, the ozone hole over Antarctica was one of those stories that raised alarms every time spring arrived in the Southern Hemisphere. Now, a new report from the World Meteorological Organization has reviewed how it behaved during 2025 and found a detail that is changing the conversation.
A concern that began decades ago
To understand why its recent behavior matters, we first have to go back to the origin of the problem.
The ozone hole appeared as a result of the deterioration of a layer in the atmosphere that protects against the Sun’s ultraviolet radiation. Among the substances responsible were chlorofluorocarbons (CFCs) , which were used for decades in refrigeration, air conditioning, aerosols and other products.
When these compounds reach the stratosphere, they can release chlorine and bromine, which take part in reactions capable of destroying ozone.
The situation prompted countries to act together and, in 1987, the Montreal Protocol was adopted , with the goal of gradually phasing out substances that damaged the ozone layer.
The change became visible over time
The recovery of the ozone layer could not happen overnight. The damage had already been done, and some of the substances that contributed to its deterioration could remain in the atmosphere for years, so the process would inevitably take time.
According to the WMO , the ozone layer began showing signs of recovery around 2000, although the process could take several decades before returning to levels similar to those seen before its deterioration.
And precisely because this recovery has not been a straight line, some of the changes recorded in recent years have begun to draw attention.
2025 recorded one of the smallest ozone holes
The WMO’s Ozone Bulletin says the ozone hole observed in 2025 was among the smallest recorded since 1992 , when severe depletion patterns began to be observed.
The report ranks it as the fourth- or fifth-smallest of that period. It was also the second consecutive year in which both its size and depth were significantly below the average recorded between 1990 and 2010.
Although those figures pointed toward recovery, 2026 once again showed that the ozone hole can change from one year to the next. During the first weeks of September, it grew rapidly, and on September 12, it reached 25 million square kilometers .
That figure was about 5 million square kilometers above the seasonal average, although it was still well below the record of 29.6 million km² set in 2006 .
But there is an important detail: this increase does not mean that the chemicals that damaged the ozone layer have returned. Scientists have linked it to extreme weather conditions, particularly a sudden drop in temperatures in the stratosphere over the South Pole, which favored the formation of Polar Stratospheric Clouds .
