Climate change hinders recovery of the ozone layer

Ozone regeneration especially in the tropics and on the southern hemisphere slowed down

Ozone hole in the southern hemisphere in 2008 © NASA
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Rising greenhouse gas concentrations in the atmosphere could have fatal effects on the Earth's ozone layer. After all, scientists have found that climate change is delaying or perhaps even completely blocking the recovery of the Earth's vital protective layer. Their results have appeared in the journal Geophysical Research Letters.

The ozone layer is an important shield of the earth against harmful UV radiation from the sun. Due to the release of propellants, humans have significantly thinned out this protective layer. Even though most states have stopped releasing ozone-depleting substances since the 1980s, the ozone layer has so far recovered only very hesitantly.

Researchers led by John Waugh of Johns Hopkins University in Baltimore and the NASA Goddard Space Flight Center in Greenbelt have now collaborated with colleagues to study the impact of current climate change on ozone depletion. They simulated the effects using the "Goddard Earth Observing System Chemistry-Climate Model", a special climate model that maps the chemical interactions and their climate impacts.

Changes in atmospheric dynamics are slowing down

The result is far from encouraging. For it has been shown that the changes in atmospheric dynamics inhibit the formation of new ozone and thus the replenishing of today's ozone gaps. "Global warming is changing the speed at which air is transported into and through the lower atmosphere, " explains Waugh. This applies especially to the tropical and southern middle latitudes. "The air moves faster through it, so less ozone is formed."

Tropical and southern hemisphere particularly affected

Particularly affected are the tropics and areas in the southern temperate latitudes. According to the simulation, the reduced production of ozone pulls around the earth like a broad band and lies, among other things, above Australia and Brazil. If the warming continues, then the ozone layer, which is heavily thinned in these areas, may never return to full density. display

If ozone levels in these regions do not return to pre-1960 levels, then there would be serious health consequences, according to Dan Lubin, ozone researcher of the Scripps Institution of Oceanography, on the results of his colleagues. "The risk of skin cancer for fair-skinned people in countries like Australia or New Zealand and also in Chile and Argentina will be higher in the 21st century than in the 20th century."

Less impact on the northern hemisphere

The polar regions and the middle latitudes of the northern hemisphere are hardly affected. Here, the ozone layer could even recover faster than previously thought. Because in these areas, climate change causes a slight temperature drop in the upper stratosphere, which slows down ozone depletion. Even with reduced replenishment of new ozone from the lower atmospheric layers, therefore, the balance may be shifted in favor of ozone growth.

Scientists have long suspected that climate change has an impact on ozone formation, but Waugh's team has now demonstrated this for the first time and estimated the extent of its impact. "Ozone is changing both in response to ozone-depleting substances and greenhouse gases, " Waugh said. If we do not take into account climate change in the analysis of ozone data, we are wrong and cause confusion.

(American Geophysical Union, 09.02.2009 - NPO)