New study shows: Ozone layer recovering over the Antarctic

The ozone layer in the Earth's atmosphere absorbs a large proportion of the sun's UV radiation. Photo: studio023 - stock.adobe.com

Significant temperature changes have been observed in the atmosphere in recent decades. Due to the increase in greenhouse gas concentrations, the troposphere, the weather layer of the atmosphere, is warming, while the stratosphere is cooling above. At the same time, the recovery of the ozone layer is warming the lower stratosphere. The fact that a warming is not observed over the Antarctic raised the question of whether the ozone layer is regenerating less effectively there. An international team of researchers, including a scientist from the University of Graz, has now refuted this theory and found that the cause is instead a slowdown in stratospheric circulation.

With the global ban on chlorofluorocarbons (CFCs) in the late 1980s, the Earth's ozone layer began to slowly recover. By absorbing a large portion of the sun's UV radiation and converting it into heat, it plays also an important role in regulating temperature. As a result, the cooling of the lower stratosphere has stalled since the 2000s, although this trend is only weak over Antarctica. Researchers have now found the cause in a slowdown in the so-called Brewer-Dobson circulation, a large-scale movement of air masses in the atmosphere. “This circulation plays an important role in the global distribution of ozone and other chemical substances,” explains climate researcher Andrea Steiner from the Wegener Centre at the University of Graz. She is one of the authors of a study led by US scientists and published in the journal AGU Advances.

Circulation changes influence temperature in the stratosphere
Most ozone is formed in the tropical stratosphere. Atmospheric circulation transports it further to the polar regions. Changes in the movement of air masses are reflected, among other things, in the temperature of the atmosphere. "Using satellite data from radio occultation measurements from 2020 to 2022, we were able to show that the slowdown in the Brewer-Dobson circulation in the southern hemisphere between October and December led to stronger warming of the southern subtropical lower stratosphere. On the other hand, it is also responsible for the cooling of the lower stratosphere over Antarctica,” reports Steiner. “This effect obscures the recovery of the ozone layer at the South Pole. However, our calculations show that it is indeed present and is only masked by the effects of the circulation change," summarises the scientist.

Publication
Recent Warming of the Southern Hemisphere Subtropical Lower Stratosphere and Antarctic Ozone Healing
Aodhan Sweeney, Qiang Fu, Susan Solomon, Stephen Po-Chedley, William J. Randel, Andrea Steiner, Pu Lin, Thomas Birner, Sean Davis, Peidong Wang
AGU Advances
https://doi.org/10.1029/2025AV001737

Andrea Steiner, portrait ©© Fotografie Carolin Bohn 2023

Andrea Steiner's research topics comprise atmospheric climate change, its drivers and impacts. Photo: Carolin Bohn

Gudrun Pichler

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