Banned ozone-depleting gas traced to China
Large increases in banned chemicals have been traced back to China by an international team of researchers.
Emissions of chlorofluorocarbons (CFCs) – one of the most harmful ozone-depleting substances – from north eastern China increased by around 7,000 tonnes per year after 2012, researchers say.
The study found that quantities of CFCs – used as insulating foams for buildings and refrigerators – used before 2010 were too small to cause the rise. Therefore the emissions are likely to have taken place prior to 2018.
Chinese authorities found no evidence of widespread production and use of ozone-depleting substances despite reports by the Environmental Investigation Agency that Chinese foam manufacturers were using CFCs after the global ban.
The chemicals are responsible for the depletion of the ozone layer, which provides protection from the sun’s ultra-violet radiation.
Increases in CFCs delay the time it takes for the ozone layer and the Antarctic ozone hole to recover.
The team also found that it is possible that smaller increases have taken place in other countries or in other parts of China.
Researchers were aware that thousands of tonnes of CFCs were being emitted, despite a global phase-out since 2010. To establish which countries were responsible, they ran computer simulations that determined the origin of the polluted air samples.
The team now aims to find out which industries are responsible for the new emissions.
The research – published in the journal Nature – was carried out by an international team involving scientists from the University of Edinburgh. The team also included other researchers from the UK, South Korea, Japan, USA, Australia and Switzerland.
Our new study has pinned down the location of the recent increase in CFC-11 emissions to the eastern provinces of China. But we still can’t be sure exactly how or why it is being produced. This work highlights the importance of continued atmospheric monitoring to verify that international treaties and protocols are working.