Early Closure of the 2025 Antarctic Ozone Hole Signals Potential Recovery

In 2025, the Antarctic ozone hole exhibited notable characteristics, developing relatively early through mid-August and reaching a maximum area of 21.08 million square kilometers in early September. This size is significantly smaller than the 26.1 million square kilometers recorded in 2023. The ozone hole began to shrink in size during September, maintaining a considerable area between 15 million and 20 million square kilometers until the end of October. A rapid decline in size occurred in November, leading to its closure on December 1, marking the earliest closure since 2019 and one of the earliest in four decades.

Smallest and shortest-lived ozone hole in 5 years closes

The 2025 ozone hole displayed higher-than-usual ozone column minimum values and lower ozone mass deficit values compared to recent years. The Copernicus Atmosphere Monitoring Service (CAMS) calculates the ozone hole area based on the ozone column being below 220 Dobson Units, primarily south of the 60º S parallel. The presence of elongated, irregular shapes indicated weaker stratospheric winds, which allowed for the mixing of ozone-rich air from outside the polar vortex. This phenomenon suggests that the reported area of the ozone hole may not fully reflect its actual extent.

Smallest and shortest-lived ozone hole in 5 years closes

The years preceding 2025, particularly 2020 through 2023, were marked by exceptionally large and long-lasting ozone holes. The 2020 ozone hole recorded the latest closing date on December 28. However, the smaller ozone holes in 2024 and 2025 have raised hopes for a potential recovery of the ozone layer, attributed to the global ban on ozone-depleting substances (ODS) established by the Montreal Protocol.

Smallest and shortest-lived ozone hole in 5 years closes

The Montreal Protocol, signed in 1987, has been pivotal in mitigating ozone depletion by banning ODS, such as chlorofluorocarbons (CFCs). A UN-backed report in 2023 indicated that this ban has not only set the ozone layer on a path to recovery but has also contributed to limiting global warming by an additional 0.5ºC. It is projected that the ozone layer could recover by 2050 to 2066 in Antarctica, contingent on continued adherence to these international agreements.

Smallest and shortest-lived ozone hole in 5 years closes

Despite the positive developments, some experts caution that the presence of large ozone holes in recent years serves as a reminder of the potential for catastrophic ozone depletion without the Montreal Protocol's intervention. The exceptional atmospheric conditions, including the effects of the Hunga Tonga volcano eruption in 2022, have also been implicated in the large ozone holes observed in 2023.

Smallest and shortest-lived ozone hole in 5 years closes

• “Rather than putting into question the effectiveness of the ODS substances ban, the fact that we have observed large ozone holes in recent years should act as a reminder that the decline in global stratospheric ozone could have reached catastrophic levels without the concerted action of the Montreal Protocol and its subsequent amendments.” — Environmental scientists

Smallest and shortest-lived ozone hole in 5 years closes

The early closure of the 2025 ozone hole, alongside the smaller sizes observed in recent years, suggests a potential shift towards recovery, underscoring the importance of continued global cooperation in environmental policies.

Smallest and shortest-lived ozone hole in 5 years closes