Updated | The shrinking hole in the ozone layer has become something of a success story among all the damages humans have inflicted upon the Earth. A new NASA study based on data from the Aura satellite confirms the success, so far, through measuring the chemicals that caused the hole in the first place.
The study, published Thursday in Geophysical Research Letters, reveals that a decline in ozone-depleting chemicals has resulted in 20 percent less depletion since 2005. Specifically chlorine levels declined by 0.8 percent each year between 2005 and 2016.
“We see very clearly that chlorine from [chlorofluorocarbons] is going down in the ozone hole, and that less ozone depletion is occurring because of it,” Susan Strahan, lead author and atmospheric scientist from NASA’s Goddard Space Flight Center, said in a statement.
The chlorofluorocarbons (CFCs) Strahan referred to are ozone-depleting chemicals that were once used in aerosol sprays, blowing agents for foams and packing materials, and refrigerants. Chlorine causes ozone depletion as the sun’s ultraviolet radiation breaks down the CFCs into chlorine.
The hole in the ozone layer was first discovered in the 1980s. This layer of the atmosphere protects the Earth from ultraviolet radiation, which can cause skin cancer and cataracts, suppress immune systems and harm plants.
Just two years after the hole was discovered, the world jumped quickly to solve the problem. Several nations signed the Montreal Protocol, which would ultimately ban CFCs, the chemicals responsible for destroying the ozone. Fast-forward decades later, and the ozone hole was measured at the smallest since 1988, NASA announced last November.
Strahan’s study is the first to look directly at measurements of chemicals to argue that the shrinking hole stems from the ban of CFCs. Using data since 2005 from the Microwave Limb Sounder on the Aura satellite, scientists gathered information on the amount of hydrochloric acid in the stratosphere, where the ozone layer is located. Hydrochloric acid is a chemical that forms once chlorine has destroyed the ozone itself.