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

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.