Researchers have discovered that eastern China is responsible for more than 60% of the recent rise in CFC-11 emissions. A search for the source of the ozone-depleting chemicals began in 2012 after the rise was found to violate the Montreal Protocol.
Instituted in 1989, the Montreal Protocol held countries to a commitment to decrease ozone-depleting gases and fix the ozone hole that had been formed. This environmental success story was questioned last year, when scientists discovered that emissions of CFC-11, one of the banned ozone-depleting chemicals, were suddenly on the rise.
The Montreal Protocol aimed to keep the world on track to repair the ozone hole by the 2060s, banning the use of ozone-depleting chemicals used in industrial processes. CFC-11, for example, is commonly used in refrigeration and the production of foams. For decades, CFC-11 emissions were declining, like many other banned chemicals, but when the decline slowed in 2012, the search for rogue emissions began.
The researchers’ findings, published in Nature on Thursday, showed that China’s CFC-11 emissions from 2008-2012 were about 6.4 gigagrams per year and increased to approximately 7.0 gigagrams per year between 2014 and 2017. Though the results cannot point to which factories are causing the emissions, weather modeling narrowed the region down to northeast China.
Until recently it was impossible to discern Chinese emissions from those of Hawaii, but air monitoring stations in Japan and Korea, as well as weather modeling, allowed the researchers to pinpoint the source of the emissions.
China has responded by saying it will crack down on the emissions as a part of its commitment to the Montreal Protocol.
The findings point to the value of air quality monitoring. According to researchers, this type of monitoring is only possible in North America, Europe and parts of Asia. Increasing the network of monitoring stations will help ensure emissions are accounted for and requirements are met.