In a shocking find, researchers have said concentration of ozone-damaging chemicals continue to rise despite ban on their use.
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 each September. CFC-11 was widely used as a foaming agent, but post the signing of the Montreal Protocol in 2010, its production was phased out.
While increase in the concentration of CFC-11 is definitely troubling, what is more worrying is that scientists are not sure at present why emissions of this gas are increasing. The new study, published in the journal Nature, documents an unexpected increase in emissions of this gas, likely from new, unreported production.
Scientists at the National Oceanic and Atmospheric Administration (NOAA) in the US say that more research needs to be carried out to figure out exactly why emissions of CFC-11 are increasing and if something can be done about it soon.
NOAA scientists and their colleagues 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, Montzka and his colleagues concluded that CFC emissions must have increased after 2012.
This conclusion was confirmed by other changes recorded in NOAA’s measurements during the same period, such as a widening difference between CFC-11 concentrations in the northern and southern hemispheres – evidence that the new source was somewhere north of the equator. Measurements from Hawaii indicate the sources of the increasing emissions are likely in eastern Asia, the study said. More work will be needed to narrow down the locations of these new emissions.