The chemical ban has resulted in shrinking of the ozone hole, according to the new study. This latest, first-of-its-kind study claims that the hole in the ozone layer is closing, thanks to the worldwide efforts for banning certain harmful chemicals. These chemicals, mostly the chlorofluorocarbons (CFCs) are the main cause of depletion of ozone layer.
Scientists all around the world were quite concerned about increasing amount of CFCs in the Earth’s atmosphere and called for an international ban. And now, it seems that their efforts have paid off. NASA scientists have informed that the hole in the Earth’s protective ozone layer is healing and this has happened due to the ban on harmful chemicals that created the massive hole. After going through the satellite data, the scientists got to know that there is almost 20 percent decrease in depletion of ozone layer due to CFCs between 2005 and 2016. Lead author Susan Strahan, an atmospheric scientist at NASA’s Goddard Space Flight Centre in Greenbelt said, “We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it.”
This was for the first time that the scientists directly measured the changes in the amount of chlorine present in the atmosphere. Chlorine is the main byproduct of CFC and is mainly responsible for ozone depletion. So to know more about chlorine concentration in atmosphere, scientists studied the data collected by the Microwave Limb Sounder (MLS) which is fitted to the Aura Satellite. Although the MLS instrument cannot directly detect chlorine atoms, it can detect the hydrochloric acid which is formed by the reaction of chlorine atom with methane and then bonding with hydrogen.
According to the study, during the Southern Hemisphere’s summer, Chlorine produced due to break down of CFCs break the ozone atoms. But during Antarctica’s winters (early July to mid-September) , when all the ozone gets destroyed, the Chlorine binds with methane. Strahan said that by around mid-October, all the chlorine compounds get conveniently converted into one gas, so by measuring the hydrochloric acid concentration, they could get the total amount of Chlorine present in the ozone layer. According to Strahan, during Southern Hemisphere’s winter, the temperatures of Antarctica are very low, so at this time the rate of ozone depletion is directly dependent on the total amount of chlorine present. This is when we want to measure ozone loss,” she said.
After analyzing the chlorine concentration in ozone layer through MLS, the scientists found out that the chlorine concentration of ozone layer decreases on an average of 0.8 percent annually. This has resulted in shrinking of ozone hole which indicates that the ozone layer is healing. Scientists have predicted the chlorine levels will decrease further and hence the ozone hole will continue to shrink in future.