Overview
- NASA and NOAA scientists report the 2026 seasonal ozone hole averaged about 9.6 million square miles during its peak and reached roughly 10.5 million square miles on September 18, ranking it the seventh‑largest in 48 years.
- Researchers attribute the expansion to an unusually large and powerful polar vortex that persisted because planetary‑scale wave activity was weak in August and September, which kept cold, ozone‑destroying air trapped over a wider area.
- Measurements show the hole’s geographic area was large but the column ozone loss was milder than some past extremes, with South Pole readings falling to about 105 Dobson units on October 17 versus the record low of 92 DU in 2006.
- Scientists say decades of cuts to chlorine and bromine under the Montreal Protocol have reduced stratospheric chemicals by roughly a third from peak levels and likely kept the 2026 hole about 1–2 million square miles smaller than it would otherwise have been.
- Multiple observing systems—satellites, weather balloons and a South Pole Dobson spectrophotometer—confirmed the findings, and researchers say continued monitoring is needed because meteorological swings can cause large seasonal variations even as long‑term recovery proceeds toward the 2070s.