Antarctic Ozone Hole Ranked Seventh Largest in 2026, Yet Recovery Stays on Track

"The annual ozone hole has been forming later in the season in recent years, which tells us the ozone layer is healing," Newman said. "But an unusually powerful polar vortex has extended ozone depletion in the Antarctic this season, allowing the hole to grow to proportions we haven't seen in a decade."

Why did the hole grow so large?

The Antarctic polar vortex (a ring of strong winds that circles the pole and creates the frigid conditions in which chlorine and bromine from human-made compounds can destroy stratospheric ozone) was unusually strong and persistent this year.

"The polar vortex was unusually large this year in part because planetary-scale weather systems that typically propagate up from the lower atmosphere and break up the vortex were especially weak in August and September," said Amy Butler, a research scientist at NOAA's Chemical Sciences Laboratory. "That weak wave action kept the strongest polar vortex winds further from the pole by several degrees of latitude, creating a larger area for conditions ideal for ozone depletion to occur."

Despite its breadth, the 2026 hole was not as deep as earlier record-setters. Using balloon-borne instruments launched from the South Pole Baseline Atmospheric Observatory, NOAA scientists measured the year's lowest overhead ozone concentration — 105 Dobson units — on October 17. The lowest value ever recorded over the South Pole remains 92 Dobson units, measured in October 2006.

How do scientists measure it?

The assessment draws on both ground-based and space-based observation. Alongside NOAA's balloon and surface instruments, satellites have monitored the ozone layer since 1979. Instruments aboard NASA's Aura satellite, the NOAA-20 and NOAA-21 satellites, and the Suomi National Polar-orbiting Partnership satellite, jointly operated by NASA and NOAA, all contributed to the report.

Is the ozone layer still recovering?

Both agencies say yes. Controls established by the Montreal Protocol in 1987, under which countries committed to replacing ozone-depleting substances with less harmful alternatives, continue to drive the stratosphere's slow repair. Chlorine levels in the Antarctic stratosphere derived from those substances have declined by about a third from their peak relative to 1980s levels, according to Stephen Montzka, senior scientist at NOAA's Global Monitoring Laboratory.

Chlorofluorocarbons and related compounds were once widely used in refrigerators, air conditioners, and building insulation, and they can linger in the atmosphere or leak from old products and landfills for many decades. As those legacy compounds gradually break down, scientists estimate the ozone hole will recover by the 2070s.

One later-forming hole at a time, the sunscreen is coming back.