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
