A decline in emissions of CFC-11 and related chemicals from eastern China

Emissions of ozone-depleting substances, including trichlorofluoromethane (CFC-11), have decreased since the mid-1980s in response to the Montreal Protocol. Recently, an unexpected increase in CFC-11 emissions since 2013 was reported, with much of the global rise attributed to emissions from eastern China. Here we use high-frequency atmospheric mole fraction observations from Gosan, South Korea, and Hateruma, Japan, together with atmospheric chemical transport model simulations, to investigate regional CFC-11 emissions from eastern China. We find that CFC-11 emissions returned to pre-2013 levels in 2019 (5.0 ± 1.0 Gg yr-1 30 in 2019 compared to 7.2 ± 1.5 Gg yr-1 for 2008 –2012, 1 s.d.), decreasing by 10 ± 3 Gg yr-1 31 since 2014 -2017. Furthermore, we find that in this region carbon tetrachloride and dichlorodifluoromethane (CFC-12) emissions, potentially associated with CFC-11 production, were higher than expected after 2013 and then declined one to two years prior to the CFC-11 emissions reduction. This suggests CFC-11 production in eastern China after the mandated global phase-out, and a subsequent decline in production during 2017-2018. We estimate that the CFC-11 bank in eastern China is up to 112 Gg larger in 2019 compared to pre-2013, most likely as a result of recent production. Nevertheless, it seems that any substantial delay in ozone layer recovery has been avoided, perhaps due to timely reporting, and subsequent action by industry and government in China.