The 2025 Antarctic ozone hole closed on December 1 – its earliest end since 2019 – and was the smallest in five years, according to new data from the Copernicus Atmosphere Monitoring Service (CAMS).
CAMS scientists have reported that this year’s hole showed higher ozone concentrations and a shorter duration than the unusually large, persistent holes recorded between 2020 and 2023. The finding is being interpreted as further evidence that the ozone layer is gradually recovering in response to the global phase-out of ozone-depleting substances (ODS).
Laurence Rouil, director of CAMS, said, “The earlier closure and relatively small size of this year’s ozone hole is a reassuring sign and reflects the steady year-on-year progress we are observing thanks to the ODS ban. This progress should be celebrated as a timely reminder of what can be achieved when the international community works together to address global environmental challenges.”
The 2025 ozone hole began forming in mid-August, following a similar early development to the large 2023 event. It reached a maximum area of 21,080,000km² in early September – well below last year’s 26,100,000km² peak. Throughout September and October, its size fluctuated between 15,00,00km² and 20,00,00km², roughly comparable to the surface area of Antarctica.
Rapid shrinkage began in early November, although a small region of low ozone lingered into the second half of the month before dissipating entirely on December 1.
CAMS scientists said the season was characterised by a higher-than-average ozone column minimum and a lower ozone mass deficit compared with recent years, both indicators of improved ozone concentrations in the Antarctic stratosphere.
Despite this year’s encouraging signs, researchers emphasised that the larger, long-lasting ozone holes seen between 2020 and 2023 illustrate the continued sensitivity of the ozone layer to atmospheric conditions. They also serve as a reminder of the potential consequences had the 1987 Montreal Protocol – which regulates nearly 100 ODS, including chlorofluorocarbons (CFCs) – not been implemented.
CAMS has published a detailed analysis of the 2025 ozone hole on its website.
In related news, Ocean observing for climate resilience remains ‘subcritical’ despite global advances, says new GOOS report