New Delhi: Antarctica’s ozone hole grew to its seventh-largest size in 48 years in 2026, despite decades of efforts to repair the Earth’s protective ozone layer. Scientists say unusually strong winds trapped cold air over the continent, creating conditions that allowed the hole to expand even as the ozone layer continued its long-term recovery.
Measurements released by NASA and the US National Oceanic and Atmospheric Administration (NOAA) on 4 November showed that the ozone hole covered an average area of 25 million square kilometres between 7 September and 13 October, more than twice the size of the United States.
At its largest, on 18 September, the hole stretched across 27.1 million square kilometres, roughly 90 per cent of the record set in September 2000.
“The annual ozone hole has been forming later in the season in recent years, which tells us the ozone layer is healing,” said Paul Newman, a senior scientist at the University of Maryland and longtime leader of NASA’s ozone research team.
Why did the ozone hole grow?
The ozone layer, located in the stratosphere, protects life on Earth by absorbing harmful ultraviolet radiation from the Sun.
For decades, chemicals containing chlorine and bromine, once widely used in refrigerators, air conditioners and other products, have been responsible for depleting this protective layer.
The damage accelerates during Antarctica’s spring, when extremely cold conditions help trigger chemical reactions that destroy ozone.
This year, a particularly strong polar vortex, a ring of winds that traps cold air above Antarctica, made matters worse.
Amy Butler, a researcher at NOAA’s Chemical Sciences Laboratory, explained that atmospheric disturbances that normally weaken the polar vortex were unusually weak during August and September.
“That weak wave action kept the strongest polar vortex winds further from the South Pole,” she said, allowing conditions favourable for ozone depletion to spread across a larger area.
Ozone recovery continues
The hole may have covered an unusually large area, but the loss of ozone was not as severe as during some of the worst years on record.
Measurements taken at the South Pole showed that ozone concentrations fell to 105 Dobson units on 17 October. By comparison, the lowest concentration recorded there was 92 Dobson units in October 2006.
Scientists say the damage would have been considerably worse without the Montreal Protocol, the 1987 international agreement to phase out ozone-depleting substances.
Newman estimated that the hole could have been another 2.6 million to 5.2 million square kilometres larger if ozone-destroying chemicals had remained at their peak concentrations in 2000.
According to NOAA, chlorine levels in the Antarctic stratosphere linked to ozone-depleting substances have fallen by about one-third from their peak.
But recovery is slow. Many of these chemicals can remain in the atmosphere for decades, continuing to damage the ozone layer long after their use has been restricted.
Scientists expect the Antarctic ozone layer to recover to its pre-depletion levels by the 2070s, provided international restrictions remain effective.
(Edited By Raunaq Lekhi)