Antarctic Ozone Hole Reached 10.6 Million Square Miles
The ozone layer depletion peaked in late September following a period of intense stratospheric cooling.
Updated on Oct. 6, 2026 in Environmental
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On September 20, 2026, the Antarctic ozone hole reached a peak measurement of 10.6 million square miles. This marks the second-largest size ever observed for this time of year.
Why it matters
Extremely low temperatures in the stratosphere, which dropped below minus 108 degrees Fahrenheit, triggered the formation of ozone-destroying clouds. Natural variability in atmospheric dynamics and a strong polar vortex further accelerated the depletion process.
The ozone hole is measured using a 220 Dobson unit threshold, with 10.6 million square miles observed at its September peak. By late September, the area had contracted to 9.3 million square miles as atmospheric conditions fluctuated.
The details
A powerful polar vortex trapped cold air over the Southern Ocean, creating the ideal environment for ozone depletion. While chlorofluorocarbon emissions from 1930 to the 1980s caused the damage, these substances have atmospheric lifetimes of 50 to 100 years, necessitating a slow recovery process.
Timeline
Emissions of ozone-destroying chlorofluorocarbons occurred from the 1930s to the late 1980s.
The Montreal Protocol began the phase-out of chlorofluorocarbons in 1989.
The ozone hole reached a record 10.8 million square miles in October 2015.
The ozone hole peaked at 10.6 million square miles on September 20, 2026.
The ozone hole may potentially remain large through November 2026.
Deeper Dive
The ozone hole's current size remains a consequence of historical chlorofluorocarbon use that the Montreal Protocol continues to regulate. This year's expansion follows a pattern established by the 1989 treaty as the atmosphere undergoes a decades-long recovery process.
The current ozone hole expansion highlights the slow rate at which the atmosphere recovers from chemical damage accumulated over decades. Future recovery depends on continued adherence to global protocols to prevent the reintroduction of ozone-depleting substances.
The takeaway
While natural atmospheric variability plays a role in yearly fluctuations, the ozone layer is expected to take six decades to fully recover. Readers should understand that long-term chemical signatures from the 20th century continue to influence global environmental health today.
Further reading
Learn more about climate shifts and historical depletion patterns in our Environmental section.
Source note: This article includes information reported by Livescience.
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