Ozone layer still depleting, contrary to popular belief

Posted February 07, 2018

The Ozone layer is situated in the Stratosphere, it is the area of the Atmosphere between 10 to 5 Km above the troposphere.

Although the exact cause of this thinning of the ozone layer at the lower latitudes could not be decoded, the scientists are suspecting that climate change might be obstructing the ozone layer to heal. But, that healing of Ozone took place at the poles. Until now, experts have expected that the global ozone layer would completely recover by the middle of the century. But British scientists say that the bottom part of the ozone layer, which is over the more populated regions of the Earth, is not improving.

William Ball, an atmospheric scientist at ETH Zurich university in Switzerland, who led the new research, said: "The finding of declining low-latitude ozone is surprising, since our current best atmospheric circulation models do not predict this effect".

An global team led by researchers from ETH Zurich and the Physikalisch-Meteorologisches Observatorium Davos have now made a troubling discovery: despite the ban on CFCs, the concentration of ozone in the lower part of the stratosphere (15 to 24 km) - where the ozone layer is at its densest - has contined to decline at latitudes between 60° S and 60° N. The scientists were able to demonstrate this using satellite measurements spanning the last three decades together with advanced statistical methods.

"The study is in lower to mid latitudes, where the sunshine is more intense, so that is not a good signal for skin cancer", said Prof Joanna Haigh at Imperial College London, a member of the worldwide research team. It is a matter of worry as the Montreal protocol no doubt has helped to reduce damage level at the poles but there are other things going on.

In the 1970s it came to know that, CFCs was severely affecting and destroying the ozone layer in the stratosphere. The reason behind the decline is not certain. One suggestion by the authors of the paper include the use of chlorine and bromine-containing chemicals known as very short-lived substances (VSLSs), used in paint strippers and solvents. One is even used in the production of an ozone-friendly replacement for CFCs. "Very short-lived substances could be the missing factor in these models".

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Today's publication combines the datasets of multiple worldwide teams, connecting information from various satellite missions since 1985.

" ... This new research is interesting and provides a novel perspective on changes in the ozone layer".

The researchers say the focus now should be on getting more precise data on the ozone decline, and determining what the cause most likely is, for example by looking for the presence of VSLSs in the stratosphere. Thinning appears to be occurring in the lower stratosphere, at 15 to 24 kilometers (9 to 15 miles) altitude, above highly populated regions between 60 degrees north and 60 degrees south.

Dr Justin Alsing from the Flatiron Institute in NY, who took on a major role in developing and implementing the statistical technique used to combine the data, said: "This research was only possible because of a great deal of cross-disciplinary collaboration".

The study was the work of researchers from Switzerland, the United Kingdom, the U.S., Sweden, Canada and Finland, and included data from satellite missions, including by NASA.