For the first time, according to NASA, satellite images show significant decline in the levels of ozone-destroying chlorine, as a result causing less ozone depletion.
Measurements show that the decline in chlorine, as a direct outcome of the signature of the Montreal Protocol in 1987, banning substances that deplete the ozone layer such as chlorine-containing manmade chemicals called chlorofluorocarbons (CFCs), has resulted in approximately 20% less ozone depletion during the Antarctic winter, compared to the first available data on the issue in 2005.
Two years after the ozone hole was discovered the international community came together, fully aware of the importance of the issue, and signed the Montreal Protocol which regulated ozone-depleting compounds. Later amendments to the Montreal Protocol completely phased out production of CFCs. Today, 197 parties have ratified the protocol, 196 nations and the European Union, one of the few universally ratified treaties in the history of the United Nations.
CFCs are long-lived chemical compounds that eventually rise into the stratosphere, where they are broken apart by the Sun’s ultraviolet radiation, releasing chlorine atoms that go on to destroy ozone molecules. Stratospheric ozone protects life on the planet by absorbing potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and damage plant life.
According to atmospheric scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, Susan Strahan, there is a direct correlation between the levels of CFCs and the percentage of ozone depletion, so that the reduction of use of CFCs had positive results in the existing ozone hole.
Nevertheless, the NASA study concludes that the 20 % decrease in ozone depletion during the winter months from 2005 to 2016 as determined from ozone measurements was expected. “This is very close to what our model predicts we should see for this amount of chlorine decline,” Strahan noted. “But we’re not yet seeing a clear decrease in the size of the ozone hole because that’s controlled mainly by temperature after mid-September, which varies a lot from year to year.”