Substantial increase in perfluorocarbons CF 4 (PFC-14) and C 2 F 6 (PFC-116) emissions in China

Abstract

The perfluorocarbons tetrafluoromethane (CF 4 , PFC-14) and hexafluoroethane (C 2 F 6 , PFC-116) are potent greenhouse gases with near-permanent atmospheric lifetimes relative to human timescales and global warming potentials thousands of times that of CO 2 . Using long-term atmospheric observations from a Chinese network and an inverse modeling approach (top–down method), we determined that CF 4 emissions in China increased from 4.7 (4.2-5.0, 68% uncertainty interval) Gg y −1 in 2012 to 8.3 (7.7-8.9) Gg y −1 in 2021, and C 2 F 6 emissions in China increased from 0.74 (0.66-0.80) Gg y −1 in 2011 to 1.32 (1.24-1.40) Gg y −1 in 2021, both increasing by approximately 78%. Combined emissions of CF 4 and C 2 F 6 in China reached 78 Mt CO 2 -eq in 2021. The absolute increase in emissions of each substance in China between 2011-2012 and 2017-2020 was similar to (for CF 4 ), or greater than (for C 2 F 6 ), the respective absolute increase in global emissions over the same period. Substantial CF 4 and C 2 F 6 emissions were identified in the less-populated western regions of China, probably due to emissions from the expanding aluminum industry in these resource-intensive regions. It is likely that the aluminum industry dominates CF 4 emissions in China, while the aluminum and semiconductor industries both contribute to C 2 F 6 emissions. Based on atmospheric observations, this study validates the emission magnitudes reported in national bottom–up inventories and provides insights into detailed spatial distributions and emission sources beyond what is reported in national bottom–up inventories.