NASA and NOAA Report Larger 2026 Antarctic Ozone Hole but Say Recovery Remains on Track

Earth's protective ozone layer remains on track for long-term recovery, even though atmospheric conditions produced a larger Antarctic ozone hole in 2026, according to NASA and the National Oceanic and Atmospheric Administration. The hole ranked as the seventh largest by area in 48 years of monitoring, although it was not as deep as other large holes on record. During peak ozone depletion season, which ran from Sept. 7 to Oct. 13, the average extent of the hole covered about 9.6 million square miles, or 25 million square kilometers. It reached its greatest one-day extent on Sept. 18 at 10.5 million square miles, or 27.1 million square kilometers. For comparison, the largest hole observed since monitoring began reached its maximum extent in September 2000. Paul Newman, a senior scientist at the University of Maryland, Baltimore County and longtime leader of NASA's ozone research team at the Goddard Space Flight Center in Greenbelt, Maryland, said the annual ozone hole has been forming later in the season in recent years, a sign that the layer is healing. He noted, however, that an unusually powerful polar vortex extended depletion this season and allowed the hole to grow to proportions not seen in a decade. Newman added that the 2026 hole could have been 1 to 2 million square miles, or 3.5 million square kilometers, larger if ozone-depleting substances were as prevalent in the atmosphere today as they were at their peak in 2000. The Antarctic polar vortex helps create the cold conditions that allow chlorine and bromine from human-made compounds to deplete stratospheric ozone. Amy Butler, a research scientist at the NOAA Chemical Sciences Laboratory, said the vortex was unusually large this year in part because planetary-scale weather systems that typically rise from the lower atmosphere and break up the vortex were especially weak in August and September. That weak wave action kept the strongest vortex winds farther from the pole by several degrees of latitude, she said, creating a larger area with conditions ideal for ozone depletion. Despite its relatively large area, this year's hole was not as deep as the record holes observed in previous decades. Using balloon-borne instruments at the South Pole Baseline Atmospheric Observatory, NOAA scientists found that ozone concentrations directly overhead reached their lowest value of the year, 105 Dobson units, on Oct. 17. The Dobson unit is the standard measurement for ozone concentration. The lowest value ever recorded over the South Pole was 92 Dobson units in October 2006. Satellite observations have been integral to tracking the ozone layer since 1979 and contributed to the report alongside NOAA's balloon and ground-based measurements. Instruments aboard NASA's Aura satellite, the NOAA-20 and NOAA-21 satellites, and the Suomi National Polar-orbiting Partnership satellite, which is jointly operated by NASA and NOAA, all supplied data. Scientists at both agencies said ongoing monitoring shows that controls established by the Montreal Protocol in 1987 continue to drive long-term recovery of stratospheric ozone. Under the agreement, countries committed to replacing ozone-depleting substances with less harmful alternatives. Stephen Montzka, a senior scientist at the NOAA Global Monitoring Laboratory, said chlorine levels in the Antarctic stratosphere derived from those substances have declined by about a third from their peak relative to 1980s levels. Chlorofluorocarbons and similar compounds were once widely used in products such as refrigerators, air conditioners, and building insulation, and they can linger in the atmosphere or leach 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.