NASA and NOAA: 2026 Antarctic ozone hole is seventh largest in 48 years, 25 million km² on average
The 2026 Antarctic ozone hole grew to its largest in a decade because of a strong polar vortex, but it was shallow. NASA and NOAA say the ozone layer is still on track to recover.
NASA and NOAA reported, as published on science.nasa.gov, that the 2026 Antarctic ozone hole ranked seventh largest by area in 48 years of monitoring. The ozone layer as a whole remains on track for long-term recovery science.nasa.gov
science.nasa.govscience.nasa.govOpen source ↗. From Sept. 7 to Oct. 13, the peak depletion season, the hole's average extent was about 9.6 million square miles (25 million square kilometers).
The greatest one-day extent for the year came on Sept. 18, at 10.5 million square miles (27.1 million square kilometers). The largest hole since monitoring began reached its maximum in September 2000. Stratospheric ozone shields life from harmful solar radiation. It is distinct from ground-level ozone, which is an air pollutant.
Why the hole grew
Paul Newman of the University of Maryland, Baltimore County, who leads NASA's ozone research team at Goddard, said the hole has formed later in the season in recent years, which indicates healing. An unusually powerful polar vortex extended depletion this season, however, and the hole grew to proportions not seen in a decade. The vortex helps create the cold conditions in which chlorine and bromine from human-made compounds deplete stratospheric ozone.
Amy Butler of the NOAA Chemical Sciences Laboratory said that planetary-scale weather systems, which usually propagate up 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 pole and created a larger area suited to ozone depletion science.nasa.gov
science.nasa.govscience.nasa.govOpen source ↗.
Despite its area, the hole was not as deep as the records of previous decades. Balloon-borne instruments at the South Pole Baseline Atmospheric Observatory showed the lowest ozone concentration overhead this year, 105 Dobson units, on Oct. 17. The lowest value ever recorded over the South Pole was 92 Dobson units in October 2006.
Recovery and monitoring
Newman said the hole could have been 1 to 2 million square miles larger if ozone-depleting substances were as prevalent today as at their 2000 peak. According to Stephen Montzka of the NOAA Global Monitoring Laboratory, chlorine in the Antarctic stratosphere from these substances has declined by about a third relative to 1980s levels. NASA and NOAA scientists attribute the recovery to the controls of the 1987 Montreal Protocol.
Chlorofluorocarbons were once widely used in refrigerators, air conditioners and building insulation. They can linger in the atmosphere or leach from old products and landfills for many decades. Scientists estimate that the ozone hole will recover by the 2070s.
Satellite data has been used to monitor the ozone layer since 1979. Instruments on NASA's Aura, NOAA-20, NOAA-21 and Suomi NPP satellites contributed to this report.
