Emissions of Ozone-Destroying Chemical Mysteriously Rising
A new study from the National Oceanic and Atmospheric Administration (NOAA) shows an "unexpected and persistent increase" in global emissions of an ozone-depleting chemical even though an international treaty forced production to completely halt by 2010.
NOAA scientists suggest that emissions are most likely from new, unreported production from an unidentified source in eastern Asia.
Chlorofluorocarbons, or CFCs, were once found in countless products, including air-conditioning, refrigeration and aerosol-spray propellants. However, it was discovered they caused a giant hole in the ozone layer, which shields the sun's dangerous ultraviolet radiation from reaching Earth's surface.
According to the NOAA analysis, published Wednesday in Nature, the rate of decline of atmospheric CFC-11 concentrations was constant from 2002 to 2012, and then slowed by about 50 percent after 2012. From 2014 to 2016, however, emissions of CFC-11 increased by 25 percent above the average measured from 2002 to 2012 despite reported production being close to zero since 2006.
As the study points out: "The increase in emission of CFC-11 appears unrelated to past production; this suggests unreported new production."
This is the first time emissions of one of the three most abundant, long-lived CFCs have increased for a sustained period since the late 1980s, the researchers found.
While the overall concentration of CFC-11 in the atmosphere is decreasing, the decline is only half as fast as what was observed a few years ago, the scientists said. Notably, the decline is also much slower than it would be without the new CFC emissions.
"We're raising a flag to the global community to say, 'This is what's going on, and it is taking us away from timely recovery of the ozone layer,'" said NOAA scientist Stephen Montzka, the study's lead author, in a statement. "Further work is needed to figure out exactly why emissions of CFC-11 are increasing, and if something can be done about it soon."
The study does not pinpoint the exact reason behind the increase of CFC-11 emissions, but Montzka and his team did offer some potential explanations.
"In the end, we concluded that it's most likely that someone may be producing the CFC-11 that's escaping to the atmosphere," he said. "We don't know why they might be doing that and if it is being made for some specific purpose, or inadvertently as a side product of some other chemical process."
Montzka noted that if the source of the emissions can be identified and controlled soon, the damage to the ozone layer should be minor. However, he warned that if it is not remedied soon, substantial delays in ozone layer recovery could be expected.