Under the Montreal Protocol, the world agreed to end the production of CFC-11 altogether by 2010.
The surge in emissions of chlorofluorocarbons, which were banned under the Montreal Protocol of 1987, was reported past year. "Therefore, it was unexpected when we saw that, starting around 2013, global emissions of one of the most important CFCs suddenly began to grow". "Any increase in emissions of CFCs will delay the time it takes for the ozone layer, and the Antarctic ozone "hole", to recover", he said.
Where are the rest of the emissions coming from?In an effort to pinpoint the source of the new emissions, researchers at the University of Bristol, Kyungpook National University, and the Massachusetts Institute of Technology looked at air quality data from monitoring stations in Hawaii, Japan, and Korea. "This was because we were interested in collecting air samples that were representative of the background atmosphere, so that we could monitor global changes in concentration and determine their atmospheric lifetimes".
"If we look at these extra emissions that we've identified from eastern China, it equates to about 35 million tonnes of Carbon dioxide being emitted into the atmosphere every year, that's equivalent to about 10% of United Kingdom emissions, or similar to the whole of London".
China is to blame for much of an increase in illegal ozone-depleting substances (ODS), a study has warned.
The team also ran computer simulations that confirmed the origin of the CFC-11 molecules.
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"We didn't find evidence of increasing emissions from Japan, the Korean peninsula, or any other country to which our networks are sensitive".
What is more disconcerting is that a major chunk of these emissions are probably the result of "new unreported production and use". "A concurrent increase in CFC-11 emissions from eastern Asia contributes to the global emission increase, but the location and magnitude of this regional source are unknown".
Now that the emissions have been discovered, it still remains to be found which industries are to be held accountable for them, as per Matt Rigby, a lead author of the study, recounts.
In March, it said it had closed down two manufacturers that were producing CFC-11.
The most plausible explanation for such an increase is that CFC-11 was still being produced, even after the global ban, and on-the-ground investigations by the Environmental Investigations Agency and the New York Times seemed to confirm continued production and use of CFC-11 even in 2018, although they weren't able to determine how significant it was.
The study reveals that no other elevated levels of CFC-11 appear to be coming from any other eastern Asian countries and that these specific areas of China are likely responsible for the majority of current CFC-11 emissions worldwide. This represents more than a doubling of emissions from the region, and accounts for at least 40% to 60% of the global increase.