According to a new study, emissions of one of the chemicals that can cause a hole in the ozone layer are on the rise, despite an international ban on the chemical by the 1987 Montreal Protocol.
The gas, Trichlorofluoromethane, or CFC-11, is a member of the family of chemicals most responsible for the giant hole in the ozone layer that forms over Antarctica every September.
• The new study, published in the journal Nature, documents an unexpected increase in emissions of the gas.
• Once widely used as a foaming agent, production of CFC-11 was phased out by the Montreal Protocol in 2010.
• The researchers are not sure at present why the emissions of the gas are increasing.
• According to the researchers, further work is required to figure out exactly why emissions of CFC-11 are increasing and if something can be done about it soon.
The study: Key Points
• For the study, researchers at NOAA and Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder, in the US made precise measurements of global atmospheric concentrations of CFC-11.
• The results showed that CFC-11 concentrations declined at an accelerating rate prior to 2002 as expected.
• Then, surprisingly, the rate of decline hardly changed over the decade that followed. Even more unexpected was that the rate of decline slowed by 50 percent after 2012.
• After considering a number of possible causes, the researchers concluded that CFC emissions must have increased after 2012.
This conclusion was confirmed by other changes recorded in National Oceanic and Atmospheric Administration’s (NOAA) measurements during the same period, such as a widening difference between CFC-11 concentrations in the northern and southern hemispheres, showing evidence that the new source was somewhere north of the equator.
The 1987 Montreal Protocol banned industrial aerosols such as chlorofluorocarbons (CFCs) that were chemically dissolving ozone, especially above Antarctica.