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The ozone hole over Antarctica was the largest in a decade in 2026 — and the seventh largest in 48 years of monitoring. The news, from a new report by NOAA and NASA, sounds alarming. But the scientists behind it insist on the second half of the sentence: long-term recovery of the ozone layer remains on track.
Understanding why both things can be true at once is the key to this story — and to why a single bad year does not undo four decades of progress.
What the measurements show
According to government data, the ozone hole reached its greatest extent for the year on 18 September, measuring 10.5 million square miles — about 90% as large as the biggest ozone hole on record, in 2000. That makes 2026 the seventh largest in the monitoring record, which stretches back 48 years. It is a sharp contrast with 2025, when the hole ranked as the fifth smallest since 1992.
Researchers say the growth was driven by an unusually powerful polar vortex — the swirling winds that circle Antarctica each winter. A strong vortex traps cold air over the pole, prolonging the chemical reactions that destroy ozone. Amy Butler, a research scientist at NOAA's Chemical Sciences Laboratory, explained that this year's vortex was partly so strong because the planetary-scale weather systems that normally disrupt it were unusually weak.
Big, but not deep
There is an important nuance in the numbers. The 2026 hole was vast in area — that is what earns it the seventh-place ranking. But it was not as chemically deep as the worst holes on record. Depth refers to how severely ozone is depleted inside the hole itself, and on that measure 2026 was less extreme than some earlier years.
That distinction matters because the depth of depletion is driven mainly by the concentration of ozone-destroying chemicals in the stratosphere — and those concentrations are falling. Levels of ozone-depleting substances have dropped by about a third since their peak around 2000, thanks to the Montreal Protocol, the 1987 treaty that phased out their production.
Why recovery is still on track
Scientists assess ozone recovery through long-term trends, not single seasons, because year-to-year size is heavily influenced by weather. "The 2026 ozone hole is large but could have been 1 to 2 million square miles larger if ozone-depleting substances were as prevalent in the atmosphere today as they were at their year 2000 peak," said Paul Newman, a senior scientist at the University of Maryland and a longtime leader of NASA's ozone research team.
Researchers estimate the ozone layer will recover by the 2070s as the older compounds disintegrate, with some assessments pointing to full recovery before 2090. The Montreal Protocol — often called the most successful environmental treaty ever agreed — is still working; the weather simply gave it a bad year.
The 2026 hole is therefore best read as a reminder, not a reversal. The atmosphere's chemistry is healing, but the polar vortex can still produce a frightening headline in any given year. Continued monitoring and compliance with the treaty are what will keep the long trend pointing the right way.
Sources: ABC News via KTBB, Science Sensei. Internal: Cyclone Murasu Aftermath Explained: Landfall, Damage and What Happens Next, NASA Swift Telescope Burns Up Over Indonesia After 22 Years in Space.