DThe ozone layer over Antarctica may not recover as well as predicted. This is the result of a study in “Nature Communications”. The authors analyzed the daily and monthly fluctuations in ozone concentrations between 2001 and 2022 at different altitudes in the stratosphere. Using satellite data, the researchers discovered that the ozone concentration in the polar vortex of the middle stratosphere has decreased by 26 percent in recent years. Since the ozone-destroying substances normally do not rise so high, the researchers suspect that the dynamics of the mesosphere, the layer of the atmosphere above the stratosphere, are changing.
Influence of the seasons
Every year from August to October, the area with particularly low ozone concentrations in the stratosphere increases over Antarctica and decreases again until December. The size and lifespan of the ozone hole varies from year to year, explains Sabine Bischof from the Helmholtz Center for Ocean Research in Kiel, depending on the temperature, dynamics and chemistry in the stratosphere. In the years 2020 to 2022, the ozone layer recovered late than average.
However, the current study does not take into account the years 2002 and 2019, when the stratosphere warmed more than usual. Due to the warm stratosphere, the ozone hole was particularly small in 2019. Therefore, experts currently do not see a trend for the ozone hole to become larger again, but rather only increased variability in atmospheric processes. “Dynamic changes in the atmosphere will certainly play a larger role in climate change in the future,” says Martin Dameris from the German Aerospace Center in Oberpfaffenhofen. The years 2020 to 2022 could be a first indication of this, “but nothing more”.
How quickly the ozone hole really closes, says Ulrike Langematz from the TU Berlin, “depends on several factors, especially the increase in greenhouse gas concentrations.” According to the experts interviewed by the Science Media Center, it is therefore important to continue to monitor ozone concentrations and movements in the atmosphere.
The Montreal Protocol takes effect
This occurred in 1987 Montreal Protocol came into force, according to which all countries of the United Nations committed to taking measures to protect the ozone layer. This particularly affected the emissions of halogenated hydrocarbons CFCs, which were banned for many applications. Atmospheric researchers then predicted that the ozone hole over Antarctica would close completely by the middle of the 21st century. How Studies have already shown in recent years to delay dichloromethane emissions, especially from China Emissions from forest fires this process by about 30 years.
Nevertheless, Peter von der Gathen from the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven considers the agreement to protect the ozone layer to be a breakthrough: “Even if the current study shows a temporally and spatially limited decline in ozone over the ozone hole over the past few years, “It does not undermine the great success of the Montreal Protocol on substances that deplete the ozone layer.”
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