2025 Antarctic Ozone Hole Among Smallest on Record, Scientists Confirm Recovery

During the peak depletion period from 7 September to 13 October 2025, the ozone hole averaged 7.23 million square miles (18.71 million square kilometers).

Scientists have delivered encouraging news for the global environment, announcing that the 2025 Antarctic ozone hole was relatively small and short-lived, reinforcing strong scientific evidence that Earth’s ozone layer is on a steady path to recovery.

According to the US National Oceanic and Atmospheric Administration (NOAA) and NASA, the 2025 ozone hole ranked as the fifth smallest since 1992, the year when the Montreal Protocol—the landmark international agreement to phase out ozone-depleting substances—began to significantly reduce harmful emissions. This finding highlights the long-term effectiveness of global cooperation in environmental protection.

Independent observations from the Copernicus Atmosphere Monitoring Service (CAMS) confirmed that the ozone hole closed on 1 December 2025, making it the earliest closure since 2019. CAMS also noted that this year’s ozone hole was the smallest recorded in the past five years, providing further reassurance of sustained recovery.

Each year, the size and duration of the Antarctic ozone hole—typically forming during the austral spring (September to November)—are influenced by a combination of stratospheric temperatures, wind patterns, and the remaining presence of ozone-depleting substances (ODS) released by human activities. While natural year-to-year variability still occurs, scientists emphasize that the long-term downward trend in ozone depletion is unmistakable.

During the peak depletion period from 7 September to 13 October 2025, the ozone hole averaged 7.23 million square miles (18.71 million square kilometers). This is roughly 30% smaller than the record-breaking ozone hole observed in 2006. Moreover, NASA and NOAA reported that the ozone hole began breaking up nearly three weeks earlier than the average observed over the past decade.

Paolo Laj, Chief of the World Meteorological Organization (WMO) Atmospheric and Environment Research Section, said scientific monitoring continues to validate earlier predictions. He explained that the recovery of the ozone layer is directly linked to the global phase-out of ozone-depleting chemicals once widely used in refrigeration, air conditioning, firefighting foams, and aerosol products.

Laj added that scientists remain confident the ozone layer could return to 1980s levels by the middle of this century, significantly reducing risks of skin cancer, cataracts, and damage to ecosystems caused by excessive ultraviolet (UV) radiation. However, he cautioned against complacency, stressing that continued scientific monitoring is essential.

The importance of international cooperation was also underscored during the United Nations Environment Assembly (UNEA) in Nairobi, held from 8–12 December, where a dedicated Multilateral Environmental Agreements Day highlighted the Montreal Protocol. Adopted on 16 September 1987, the treaty is widely regarded as the most successful environmental agreement ever, and remains one of the few treaties to achieve universal ratification.

The WMO and the United Nations Environment Programme (UNEP) jointly oversee a quadrennial Scientific Assessment of Ozone Depletion, which evaluates global progress using the best available science. The most recent assessment, published in 2022, concluded that if current policies remain in place, the ozone layer is expected to recover to 1980 levels by around 2066 over Antarctica, 2045 over the Arctic, and 2040 for the rest of the world. The next assessment is scheduled for 2026.

Supporting this progress, NOAA scientist Stephen Montzka noted that levels of ozone-depleting substances in the Antarctic stratosphere have fallen by about one-third since peaking around the year 2000. NASA scientist Paul Newman added that without the Montreal Protocol, the 2025 ozone hole would have been more than one million square miles larger, underscoring the treaty’s tangible impact.

Laurence Rouil, Director of CAMS, described the early closure and smaller size of the 2025 ozone hole as a powerful reminder of what global cooperation can achieve. He said the progress should be celebrated as proof that coordinated international action can successfully address complex environmental challenges.

Overall, scientists agree that the 2025 findings provide strong evidence that the ozone layer is healing, offering one of the clearest examples of how science-based policy and sustained global commitment can deliver lasting environmental benefits.