New Delhi: Measurements from Nasa and Noaa reveal a worrying milestone for the Antarctic ozone hole, though there remains a reason for scientists to remain optimistic. The ozone hole over Antarctica grew to its seventh-largest size in 48 years of monitoring this year, reviving concerns about the health of Earth's protective shield against harmful solar radiation.
However, researchers from Nasa and the National Oceanic and Atmospheric Administration stated that the unusually large hole was predominantly driven by weather conditions, and the ozone layer remains on track for long-term recovery. According to measurements released on November 4, the ozone hole covered an average area of around 25 million square kilometres between September 7 and October 13, 2026.
At its maximum extent on September 18, it expanded to approximately 27.1 million square kilometres, which is nearly 90% of the largest ozone hole ever recorded back in 2000. Scientists attributed this year's expansive hole to a powerful polar vortex, a band of strong winds circling Antarctica that traps extremely cold air over the continent.
These freezing conditions encourage the formation of specialized clouds high in the atmosphere, where chlorine and bromine released by human-made chemicals trigger reactions that destroy ozone. This year, weather systems that normally weaken the polar vortex were unusually weak during August and September, allowing the vortex to remain stronger and cover a broader area.
The ozone layer acts as a natural sunscreen high above Earth, absorbing much of the Sun's harmful ultraviolet radiation. Its depletion is primarily caused by chemicals such as chlorofluorocarbons, which were once widely used in refrigerators, air conditioners, and aerosol products. When these substances reach the upper atmosphere, sunlight releases chlorine and bromine atoms that break down ozone molecules, potentially increasing health risks like skin cancer and cataracts while damaging ecosystems.
Despite this year's seasonal increase, specialists emphasize that international agreements are working. The 1987 Montreal Protocol successfully helped phase out many ozone-destroying chemicals, reducing chlorine levels in Antarctica's upper atmosphere by roughly a third from their peak in the 1980s. Noaa estimates that without these critical restrictions, the 2026 ozone hole could have expanded by an additional 3.5 million square kilometres. Experts ultimately expect the Antarctic ozone hole to fully recover by the 2070s, even as legacy chemicals continue lingering in the atmosphere for decades to come.