Unusual Antarctic weather enlarges ozone hole while long-term recovery continues
Where it stands
US weather and space researchers reported an unusually large Antarctic ozone hole on 4 November 2026. The assessment comes from the National Oceanic and Atmospheric Administration (NOAA) and the space agency NASA. The ozone hole is an area where the protective ozone layer becomes severely thinned during the southern spring. Its average area during the main depletion season was about 25 million square kilometres. That made it the seventh-largest in 48 years of monitoring. A powerful polar vortex helped maintain a large area of very cold air, allowing ozone-destroying reactions to continue. Scientists still see long-term recovery as controls reduce ozone-depleting chemicals. This year’s weather and that longer trend operate together. The researchers say the hole would have been larger if those chemicals had remained as abundant as before international controls.
Background
Ozone in the stratosphere absorbs harmful ultraviolet radiation from the Sun. Some human-made chemicals release chlorine or bromine after reaching this layer of the atmosphere. Under Antarctic conditions, these substances can take part in reactions that destroy ozone. Very cold air allows polar stratospheric clouds to form. Reactions on their particles prepare chlorine to destroy ozone when sunlight returns. The polar vortex, a ring of strong winds, helps keep the cold Antarctic air isolated. The Montreal Protocol controls substances responsible for this damage. Many remain in the atmosphere for decades, so recovery takes time. Weather changes also affect the size of the hole from year to year. Researchers therefore examine both annual conditions and the longer chemical trend when assessing recovery.
How it developed
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4 November 2026How it started
Monitoring finds a large seasonal area alongside lower chemical pressure
The average ozone-hole area was about 25 million square kilometres from 7 September to 13 October 2026. NOAA and NASA linked its large size to an unusually strong polar vortex. Satellite measurements and ground-based observations track the layer’s condition. The researchers say international controls on ozone-depleting substances continue to support recovery, even as this year’s weather increased depletion.
Why it matters for UPSC
For GS3, explain how atmospheric chemistry and polar weather combine to affect ozone. Use the Montreal Protocol to connect international controls with gradual environmental recovery.
Key terms
Sources (2)
- NOAA and NASA · official · Measurements of the 2026 Antarctic ozone hole5 Nov, 12:55 pm
- NASA Ozone Watch · official · Ozone hole facts5 Nov, 12:55 pm