The ozone hole in Antarctica in 2021 is deeper and larger than usual

The ozone hole over the southern hemisphere is deeper again this year and larger than average because of the colder-than-normal winter atmosphere over the region. It reached its maximum extent Oct. 7 and was the 13th largest since 1979, according to NASA and NOAA.

The ozone hole peaked at 24.8 million square kilometers (9.6 million square miles) in 2021 and began shrinking in mid-October, according to NASA satellite observations.

On Oct. 7, NOAA scientists recorded a total atmospheric ozone concentration of 102 Dobson units, the 8th lowest since 1986. Prior to the ozone hole in the 1970s, the average ozone concentration over the South Pole in September and October ranged from 250 to 350 Dobson units.

At altitudes of 14 to 21 kilometers (8 to 13 miles), ozone was almost completely absent during the maximum ozone hole.

“This is a large ozone hole because of colder-than-average stratospheric conditions in 2021,” said Paul Newman, chief Earth science scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Ozone is a gas composed of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (stratosphere)2.

Ozone protects life on Earth from ultraviolet (UV) radiation from the sun. In the lower atmosphere (troposphere) near the Earth’s surface, ozone is formed by chemical reactions between air pollutants from car exhausts, gasoline fumes, and other emissions. At ground level, high concentrations of ozone are dangerous for humans and plants.

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