Through direct satellite observation, scientists have for the first time shown that levels of ozone-destroying chlorine are declining, resulting in less ozone depletion. According to paper published in the journal Geophysical Research Letters, decline in chlorine following an international ban on chlorofluorocarbons (CFCs) has resulted in 20 percent less ozone depletion since 2005.
“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,” said Susan Strahan, an atmospheric scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
To find out if CFC ban is actually contributing to the recovery of the ozone layer, researchers studied data gathered by a JPL’S Microwave Limb Sounder (MLS) aboard the Aura satellite. Using the data collected by MLS every winter – from early July to mid-September (between 2005 to 2016), the team was able to determine changes in ozone levels year to year. And sure enough, there was 20 percent decrease in ozone depletion.
“This is very close to what our model predicts we should see for this amount of chlorine decline,” explained Strahan. “This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs. 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.”