Antarctic Ozone Hole Swells to Its Biggest Size in a Decade, NASA Says

The Antarctic ozone hole grew in 2026 to a size scientists have not seen in a decade, but NASA and NOAA say the ozone layer is still healing and remains on track to recover later this century, according to ScienceDaily.

The cause was weather, not a new surge in pollution. An exceptionally strong polar vortex kept conditions ripe for ozone loss across a wider area, the agencies said.

The key numbers

Seventh-largest in 48 years: the 2026 hole ranks seventh by average seasonal area in 48 years of observations.
9.6 million square miles (25 million square kilometers): the average area between Sept. 7 and Oct. 13, when depletion peaks. That is more than twice the size of the United States.
10.5 million square miles (27.1 million square kilometers): the maximum extent, reached on Sept. 18. That is about 90% of the largest hole ever measured, on Sept. 9, 2000.
105 Dobson units: the lowest reading over the South Pole in 2026, on Oct. 17. The record low is 92 Dobson units, set in October 2006.
1 to 2 million square miles: how much larger the hole could have been if ozone-depleting substances were as common as at their 2000 peak, according to NASA's Paul Newman.

What is behind the growth

Ozone is destroyed when chlorine and bromine from human-made compounds reach the stratosphere and react on the surface of special clouds over Antarctica. Those clouds form in very cold air trapped by the polar vortex, a seasonal band of strong winds around the continent.

In 2026, disturbances that would normally weaken the vortex were unusually quiet. Amy Butler, a research scientist at the NOAA Chemical Sciences Laboratory, said planetary-scale weather systems that usually rise from the lower atmosphere and break up the vortex were especially weak in August and September. That kept the strongest vortex winds several degrees of latitude farther from the South Pole, creating a larger area for ozone loss.

Despite the size, the 2026 hole did not see the same extreme ozone loss as record-setting years 10 or 20 years ago, the sources said.

What this means for the ozone layer

Stratospheric ozone acts as Earth's natural sunscreen, shielding living things from dangerous solar radiation. The agencies stress that the big hole is not a sign of failed recovery. Newman, a University of Maryland senior scientist who leads NASA's ozone research team, said the hole has been forming later in the season in recent years, which shows the layer is healing. The powerful vortex stretched out the depletion this year.

The results also show the payoff of international limits on ozone-destroying chemicals. Without those reductions, the affected area could have been substantially greater.

How scientists measure it

NOAA researchers launched instruments on weather balloons from the South Pole Baseline Atmospheric Observatory and took readings with a Dobson Ozone Spectrophotometer. Satellites have also tracked the ozone layer since 1979, and the 2026 measurements included data from NASA's Aura satellite and NOAA-20 and NOAA-21.

A reading of 100 Dobson units equals a layer of ozone about 1 millimeter thick, roughly the thickness of a dime, if all the ozone in the column were compressed at standard temperature and pressure at sea level.

Around Prague, based on reporting by ScienceDaily

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