ZJU-CERS Scientists Discovers a Decline in Emissions of CFC-11 and Related Chemicals From Eastern China
On Jan.10,2021, CERS researcher Xuekun Fang published a paper as the co-first auther on Nature. The results show that since 2018, the emission of CFC-11 (CCl3F; monochloromethane) in eastern China has shown a rapid downward trend, contributing about 60% of the global CFC-11 emission reduction. The expected delay in the recovery of the ozone layer will be avoided. The study has cooperated with researchers from Bristol University, kyungbei University, Japan's National Environmental Research Institute, Massachusetts Institute of technology, University of California, San Diego, etc
Emissions of ozone-depleting substances, including trichlorofluoromethane (CFC-11), have decreased since the mid-1980s in response to the Montreal Protocol. In recent years, an unexpected increase in CFC-11 emissions beginning in 2013 has been 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 gigagrams per year in 2019, compared to 7.2 ± 1.5 gigagrams per year for 2008–2012, ±1 standard deviation), decreasing by 10 ± 3 gigagrams per year since 2014–2017. Furthermore, we find that in this region, carbon tetrachloride (CCl4) and dichlorodifluoromethane (CFC-12) emissions—potentially associated with CFC-11 production—were higher than expected after 2013 and then declined one to two years before the CFC-11 emissions reduction. This suggests that CFC-11 production occurred in eastern China after the mandated global phase-out, and that there was a subsequent decline in production during 2017–2018. We estimate that the amount of the CFC-11 bank (the amount of CFC-11 produced, but not yet emitted) in eastern China is up to 112 gigagrams larger in 2019 compared to pre-2013 levels, probably as a result of recent production. Nevertheless, it seems that any substantial delay in ozone-layer recovery has been avoided, perhaps owing to timely reporting and subsequent action by industry and government in China.