Antarctic ozone hole hits biggest size in 20 years as vortex intensifies
The Antarctic ozone hole swelled to 27.4 million square kilometres in September, the largest in two decades.
September's Antarctic ozone hole reached 27.4 million square kilometres, the biggest it has been in 20 years. Only twice before has it grown larger: in 2000 it peaked above 28 million square kilometres and in 2015 it hit 27.9 million.
Scientists predicted this severe hole months earlier when they spotted a strong polar vortex and unusually cold temperatures gathering over Antarctica. A strong polar vortex and cold temperatures create the right environment for ozone-depleting gases to activate and destroy the protective layer.
The good news: despite its size, the hole hasn't reached the deepest damage of past years. And the Montreal Protocol, a global treaty signed in 1987, is still working.
Levels of ozone-harming substances in the atmosphere have dropped by about a third since their peak around 2000.
- 27.4 million square kilometres
- Peak size
- September 2026
- Month reached
- 20 years
- Largest since
- 28 million square kilometres in 2000
- Previous peak
Why it mattersLarger ozone holes mean more harmful ultraviolet radiation reaches Earth's surface, raising risks of skin cancer and cataracts.
AustraliaAustralia, being closer to Antarctica, faces higher UV exposure when the ozone hole expands; Australians already have high skin cancer rates and should take extra care outdoors.
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