The seasonal ozone layer above Antarctica is shrinking, but the densely populated geographic latitudes do not regenerate the ozone layer. The ozone layer extending over an area of about 20 to 30 kilometers above the Earth’s surface absorbs a significant part of harmful ultraviolet radiation from the sun, helping to protect against sunburn and skin cancer. Ultraviolet radiation is also responsible for damage to plants and plankton.
The ozone layer has been thinned since the 1970s, because chlorine released from man-made compounds – CFC gases – is responsible for the ability to break ozone molecules at incredible speed under certain conditions. The worst situation has been observed over Antarctica, where ozone hole has been developing since September and November of each year since the beginning of the 1980s – reads the Phys.org scientific news portal.
The Montreal Protocol, which came into force in 1989, has now limited the release of CFCs, thanks to the UNEP’s international treaty, which has resulted in the regeneration of the Antarctic and the ozone layer over the Arctic. At lower latitudes, ie 60 degrees north latitude and 60 degrees south latitude, there is no sign of regeneration due to high ozone depletion at the lower limit of the stratosphere.
According to Joanna Haigh, co-author of Imperial College London, co-author of the study of Atmospheric Chemistry and Physics in the journal of the European Geoscience Society (EGU), the damage caused by the thinning of the ozone layer at lower latitudes may be worse than at poles. He added: “The rate of ozone depletion is lower than that experienced before the Montreal Protocol came into force, but ultraviolet radiation is much more intense in these areas, and there are far more people living there.”
Scientists who have based their satellite data on satellite data are not yet aware of what causes the ozone depletion in the affected regions. One possible explanation is that climate change alters the general circulation of the atmosphere – a large-scale coherent system of airflows – which results in the ozone depletion of tropical areas. Another possibility is that very short-lived substances (VSLSs) containing chlorine and bromine destroy ozone near the lower limit of the stratosphere.
The team leader William Ball, the Zurich University of Technology (ETH Zürich), and his colleagues were surprised by the results because the best simulation models used to assess the evolution of atmospheric circulation did not show this phenomenon. According to the expert, these short-lived materials may represent the missing piece in these models. Researchers have so far assumed that these substances will not stay in the atmosphere enough time to reach the stratosphere and affect the ozone layer, but it seems that further testing is needed to detect this.
Source: erdekesvilag.hu / Kép: civilhetes.hu /