Earlier this year, the United Nations announced some much-needed, positive news about the environment: The ozone layer, which shields the Earth from the sun’s harmful ultraviolet radiation, and which was severely depleted by decades of human-derived, ozone-destroying chemicals, is on the road to recovery.
The dramatic turnaround is a direct result of regulations set by the 1987 Montreal Protocol, a global treaty under which nearly every country in the world, including the United States, successfully acted to ban the production of chlorofluorocarbons (CFCs), the main agents of ozone depletion. As a result of this sustained international effort, the United Nations projects that the ozone layer is likely to completely heal by around the middle of the century.
But a new MIT study, appearing in Nature Geoscience, identifies another threat to the ozone layer’s recovery: chloroform — a colorless, sweet-smelling compound that is primarily used in the manufacturing of products such as Teflon and various refrigerants. The researchers found that between 2010 and 2015, emissions and concentrations of chloroform in the global atmosphere have increased significantly.
They were able to trace the source of these emissions to East Asia, where it appears that production of products from chloroform is on the rise. If chloroform emissions continue to increase, the researchers predict that the recovery of the ozone layer could be delayed by four to eight years.
“[Ozone recovery] is not as fast as people were hoping, and we show that chloroform is going to slow it down further,” says co-author Ronald Prinn, the TEPCO Professor of Atmospheric Science at MIT. “We’re getting these little side stories now that say, just a minute, species are rising that shouldn’t be rising. And certainly a conclusion here is that this needs to be looked at.”
Xuekun Fang, a senior postdoc in Prinn’s group, is the lead author of the paper, which includes researchers from the United States, South Korea, Japan, England, and Australia.