Inverse Modeling Revealed Reversed Trends in HCFC-141b Emissions for China during 2018-2020.

Having the highest ozone-depleting potential among hydrochlorofluorocarbons (HCFCs), the production and consumption of HCFC-141b (1,1-dichloro-1-fluoroethane, CHCClF) are controlled by the Montreal Protocol. A renewed rise in global HCFC-141b emissions was found during 2017-2020; however, the latest changes in emissions across China are unclear for this period. This study used the FLEXible PARTicle dispersion model and the Bayesian framework to quantify HCFC-141b emissions based on atmospheric measurements from more sites across China than those used in previous studies. Results show that the estimated HCFC-141b emissions during 2018-2020 were on average 19.4 (17.3-21.6) Gg year, which was 3.9 (0.9-7.0) Gg year higher than those in 2017 (15.5 [13.4-17.6] Gg year), showing a renewed rise. The proportion of global emissions that could not be exactly traced in 2020 was reduced from about 70% reported in previous studies to 46% herein. This study reconciled the global emission rise of 3.0 ± 1.2 Gg year (emissions in 2020 - emissions in 2017): China's HCFC-141b emissions changed by 4.3 ± 4.5 Gg year, and the combined emissions from North Korea, South Korea, western Japan, Australia, northwestern Europe, and the United States changed by -2.2 ± 2.6 Gg year, while those from other countries/regions changed by 0.9 ± 5.3 Gg year.