21 May, 2020
2 Min Read
The scientists have observed for the first time that levels of ozone-destroying chlorine are declining, resulting in less ozone depletion. There has been an international ban on chlorine-containing human made chemicals called chlorofluorocarbons (CFCs). Measurement show that this has resulted in about 20% less ozone depletion during the Antarctic winter than there was in 2005.
Stratospheric ozone protects life on the planet by absorbing potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, CFCs are long-lived chemical compounds that eventually rise into the stratosphere.
In the long months of polar winter, chemical reactions take place in Polar Stratospheric Clouds that could not take place anywhere else in the atmosphere. These reactions convert the inactive chlorine in CFCs into more active forms, especially chlorine gas (Cl2). When the sunlight returns to the South Pole in October, UV light rapidly breaks the bond between the two chlorine atoms, releasing free chlorine.
Chlorine atoms go on to destroy ozone molecules, resulting in Antarctic ozone hole. The measurements are made by Microwave Limb Sounder (MLS) aboard the Aura satellite, which has been monitoring continuously since 2004.
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