The annual ozone hole over Antarctica this year was relatively modest in size, ranking as the fifth smallest since 1992, according to new assessments from the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA). Scientists attribute this encouraging trend to the ongoing decline of ozone-depleting chemicals in the atmosphere - a direct result of global action under the Montreal Protocol.

Ozone thinning typically peaks during the Antarctic in late winter or early spring when sunlight returns to the polar region and interacts with frigid stratospheric conditions. To track these changes, researchers rely on a combination of satellite sensors, ground-based instruments, and balloon-borne measurements.

Between 7 September and 13 October, the ozone hole averaged 7.23 million square miles (18.71 million square kilometres) equal to roughly twice the size of the continental United States. Its largest single-day extent occurred on 9 September, reaching 8.83 million square miles (22.86 million square kilometres). While still vast, this year’s hole was significantly smaller than the record set in 1996, which averaged 10.27 million square miles (26.60 million square kilometres).

Looking at the full historical record dating back to 1979, 2025 ranks as the 14th smallest ozone hole in 46 years of satellite observations. The improvement reflects a steady recovery trend since the early 2000s, though experts caution that full restoration to pre-1980 levels will take decades.
The ozone layer is crucial to protect life on Earth as we know it because it acts like a sunshield against harmful ultraviolet (UV) radiation. When depleted, more UV rays reach the surface, increasing risks of skin cancer, cataracts, and crop damage. The primary culprits, chlorine and bromine-based compounds once common in refrigerants and aerosols, remain in the atmosphere for decades, even after being banned under the 1987 Montreal Protocol. 

“We’re seeing ozone holes form later, break up earlier, and trend smaller than in previous decades,” said Paul Newman, a senior scientist at the University of Maryland-Baltimore and longtime leader of NASA’s ozone research team at Goddard Space Flight Center as well as a former co-chair of the Scientific Assessment Panel to the Montreal Protocol. 

While this year’s update is great news for ozone layer recovery, the size and depth of the annual hole can vary greatly from year to year, and vigilance is crucial. While the parties to the Montreal Protocol are ‘fixing the hole’ it is far from a job completed as noted by Paul Newman when he said, “We still have a long way to go before we recover to 1980s levels.” 

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Full NASA 2025 ozone report available here.

Latest status of the ozone layer over the Antarctic available at NASA’s ozone watch

Contact: Stephanie Haysmith, Communications & Public Information, Montreal Protocol Ozone Secretariat, stephanie.haysmith@un.org