New research from the National Oceanic and Atmospheric Administration (NOAA) and NASA shows the Antarctic ozone hole is the fifth smallest it has been in more than 30 years. The hole reached its peak for 2025 in early September, measuring 8.83 million square miles (22.87 million square kilometers), about 30% smaller than the record extent observed in 2006.
Scientists say the improvement reflects the long-term success of the Montreal Protocol, the global pact that began phasing out ozone-destroying chemicals in 1992. NASA researchers noted that this year’s hole would have been over one million square miles (2.59 million square kilometers) larger if chlorine levels in the atmosphere were still at late-1990s levels. Natural temperature and circulation patterns also contributed to this year’s smaller size.
As the ozone layer continues its steady recovery, click through the gallery to find out what happened to the once-feared “ozone hole.”