By September 12, 2026, the Antarctic ozone hole had stretched to about 25 million square kilometres, roughly 5 million square kilometres larger than the average for mid-September, according to the Copernicus Atmosphere Monitoring Service, or CAMS. The area is bigger than the 14.2 million square kilometres of the Antarctic continent itself, and it grew fastest in the first days of September.
The figure sits well short of the 29.6 million square kilometres measured on September 9, 2006, the largest ever recorded, yet it is a jump from a year in which the hole was among the smaller ones in decades.
What Copernicus measured and what it left unchanged
In its statement of September 16, timed to the UN International Day for the Preservation of the Ozone Layer, CAMS said the hole passed 15 million square kilometres by late August, slightly earlier than average and matching 2025’s timeline, then expanded quickly. The service links the early September surge to unusually cold temperatures around 20 kilometres above the South Pole, the conditions that let ozone-destroying chemistry run fastest.
The picture is not uniform. CAMS notes that other diagnostic measures, including the minimum ozone column values and the ozone mass deficit, stayed close to historical norms. An area that is large but shallow is a different situation from one that is large and deep.
A hole that usually keeps growing into October
The EU Space Programme’s image-of-the-day page on the 2026 season observes that the Antarctic ozone hole typically reaches its maximum extent between mid-September and early October and says forecasts pointed to continued expansion beyond September 12. The 25 million figure is therefore a mid-season reading, not a declared peak, and no seasonal maximum for 2026 had been published at the time of writing.
NASA’s Ozone Watch tracks the same season from the OMPS instrument on the Suomi NPP satellite, defining the hole as the area of total column ozone below 220 Dobson Units, a level absent from Antarctic observations before 1979. The site was updated on September 29. It follows four statistics for each season: hole area, minimum ozone, ozone mass deficit and polar cap ozone, which is why an area figure like CAMS’s 25 million can be read alongside depth measures that tell a quieter story.
NASA’s explanation of the mechanism, on the same Ozone Watch pages, is that very low temperatures are needed to form polar stratospheric clouds, and that reactive chlorine released on those cloud surfaces destroys ozone once sunlight returns in Antarctic spring, from August to October. Cold, in other words, sets the size, and chlorine sets the ceiling.
Recovery on schedule, but with wide swings between years
CAMS Director Laurence Rouil put the year-to-year swings in these words: “The Antarctic ozone hole’s development can vary considerably from year to year, depending on a range of atmospheric and chemical factors.” Last year’s hole shows the range. NOAA and NASA reported in their 2025 ranking that the hole peaked at 22.86 million square kilometres on September 9, 2025, the fifth smallest since 1992. NASA senior scientist Paul Newman said it would have been more than one million square miles larger with the chlorine levels of 25 years earlier, and NOAA’s Stephen Montzka said ozone-depleting substances in the Antarctic stratosphere have fallen by about a third since peaking around 2000. NOAA’s Laura Ciasto credited a weaker-than-normal polar vortex in August with keeping temperatures above average.
The 2026 area is not a reversal of that chemistry so much as a reminder of how much weather matters. Set against last year’s numbers, the 2026 reading is already about 2.1 million square kilometres above the full-season peak of 2025, with the season still running, and CAMS points to cold stratospheric temperatures over the pole as the reason for the early growth. ESA’s account of 2023 shows the same effect in the other direction: that year’s hole reached 26 million square kilometres on September 16, and ESA’s Claus Zehner still said the global ozone layer should recover to normal levels around 2050 on the strength of the Montreal Protocol.
The long-range schedule for the Antarctic is later. The 2022 WMO and UNEP scientific assessment expects Antarctic total column ozone to return to 1980 values around 2066 if the Montreal Protocol continues to be followed, a date that a single cold September does not move. The same document records a setback that has been contained: unexpected CFC-11 emissions between 2012 and 2019 threatened the recovery, and without the later cuts, particularly from northeastern China, the closing of the hole would have been delayed by about three years. The number that will test the recovery story this year is the seasonal maximum, which CAMS and NASA have yet to report.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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