Part of the protective ozone shield may be thinning over heavily populated areas: Study
The ozone layer – which protects life on Earth from high-energy radiation – has continued to thin over the last three decades, a study has warned.
In the 20th century, when excessive quantities of ozone- depleting chlorinated and brominated hydrocarbons such as CFCs were released into the atmosphere, the ozone layer in the stratosphere – ie at altitudes of 15 to 50 kilometres – thinned out globally.
The Montreal Protocol introduced a ban on these long- lasting substances in 1989.
At the turn of the millennium, the loss of stratospheric ozone seemed to have stopped. Until now, experts have expected that the global ozone layer would completely recover by the middle of the century.
However, a team led by researchers from ETH Zurich and the Physikalisch-Meteorologisches Observatorium Davos in Switzerland have found that despite the ban on CFCs, the concentration of ozone in the lower part of the stratosphere has continued to decline at latitudes between 60 degree South and 60 degree North.
The study, published in the journal Atmospheric Chemistry and Physics, used satellite measurements spanning the last three decades together with advanced statistical methods.
Ozone is formed in the stratosphere, mainly at altitudes above 30 kilometres in the tropics. From there it is distributed …read more