This year’s Antarctic ozone hole swelled to about 25 million square kilometers, bigger than Antarctica itself

The Antarctic ozone hole measured an estimated 25 million square kilometers on Sept. 12, 2026, according to the Copernicus Atmosphere Monitoring Service, or CAMS. That is far larger than Antarctica itself, which covers about 14.2 million square kilometers, and about 5 million square kilometers above the average for that point in the season. At that size the hole would stretch well beyond the continent’s coastline.

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CAMS also stressed what did not change. The ozone column minimum and the ozone mass deficit, two other measures it tracks, stayed close to average values, and the hole developed at a typical rate from the second half of August onward, in line with the previous 46 years. In other words, the large area reflects a stronger-than-average season in one dimension, not a hole that is deeper or heavier in ozone loss than usual.

What CAMS measured and when

The figures come from a CAMS newsflash issued from Bonn on Sept. 16, timed to the U.N. International Day for the Preservation of the Ozone Layer. CAMS is implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Union. The service said the hole reached 15 million square kilometers by the end of August, slightly earlier than average. Last year’s hole crossed the same threshold on Aug. 30, so the early crossing is becoming a familiar pattern rather than an outlier, even as the later growth varies.

By Sept. 12 the estimate had risen to 25 million, and forecasts at the time pointed to a possible further increase in mid-September. Because the release was issued before the season’s end, the 25 million figure is a mid-September estimate, not a confirmed seasonal peak. A later measurement could be higher or lower, and CAMS follows the hole through the season until it closes.

A report that mixed up two numbers

Coverage of the CAMS release has not always kept the figures straight. MercoPress, on Oct. 21, carried a headline saying the hole reached 15 million square kilometers during September, while its own text gives 15 million as the size reached by the end of August and about 25 million as the Sept. 12 figure. The Copernicus release matches the text of that report, not its headline, so anyone citing the 15 million figure for September is repeating the earlier end-of-August milestone, not the size the hole reached on Sept. 12.

The wire service Anadolu reported the same 25 million estimate for early September in a story dated Sept. 16, again noting it was about 5 million above the period’s average and that the area could grow further. Neither report treats it as a record. Down To Earth in India also relayed the Sept. 12 date and the 25 million figure, and likewise noted that forecasts showed room for further growth.

Where 25 million sits against the record and recent years

The largest hole on record spanned 29.6 million square kilometers on Sept. 9, 2006, a month that also had the largest average area over a consecutive multi-week period. At roughly 25 million, the 2026 estimate sits well below that mark. CAMS says recent years have shown smaller and shorter-lived holes, a pattern it links to ongoing recovery of the ozone layer.

The recovery framing matters for reading a single number, since one large day does not make a trend. The 2025 hole also reached 15 million square kilometers by Aug. 30, and CAMS reported in a release on the 2025 season that it closed on Nov. 30, the earliest closure since 2019, and was the smallest in five years.

The cold snap behind the growth

CAMS observed that the rapid growth in early September coincided with a sudden drop in minimum temperature at about 20 kilometers above the South Pole, at the 50 hectopascal pressure level. Ozone loss over Antarctica depends on very cold stratospheric conditions, so a cold spell can speed the hole’s expansion even in a year when other indicators look ordinary. CAMS did not claim the temperature drop was the sole cause; it described the two as coinciding, and the service has not said whether the cold spell persisted after mid-September.

Laurence Rouil, the director of CAMS, said the development of the Antarctic ozone hole can vary considerably from year to year, and that CAMS provides the high-quality data, forecasts and analyses needed to understand the state of the ozone layer. A year with a larger-than-average area but near-average depth and mass deficit fits that description of year-to-year swings rather than a break from the recovery trend. None of the coverage reviewed suggests the 2026 season reverses the multi-year improvement CAMS describes, and the service itself calls recent years a run of smaller, shorter-lived holes.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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