Sustained Increases in Hydrofluorocarbon Emissions from China and Implications for Global Emissions

Hydrofluorocarbons (HFCs), which are potent greenhouse gases and widely used as replacements for ozone-depleting substances, are controlled under the Montreal Protocol. China is considered an emission hot region of HFCs, however, the observations and emission quantifications are still insufficient. In this study, we report new high-frequency in situ observations of HFC-125, HFC-134a, and HFC-143a at the Changdao (CHD) station, whose emission sensitivity to northern China is higher than those of previously used stations to better quantify emissions. Combining these observations at CHD with an inverse modeling approach, we present the most recent emission estimates for northern China and reveal the distinct spatial distributions of HFC emissions that have not been previously uncovered, facilitating different priorities of provinces in future controls for HFCs. Subsequently, we show that the combined CO2-equivalent emissions of these HFCs in China increased rapidly from 7.1 ± 2.5 Mt CO2-equivalent yr-1 (2.2 ± 0.8% of global totals) in 2005 to 206.4 ± 15.9 Mt CO2-equivalent yr-1 (20.3 ± 1.8% of global totals) in 2022. Finally, we reveal that in terms of per area, per capita, and per gross domestic product, CO2-equivalent emissions of HFCs in China were increasing fast and becoming larger than the global average level. Our new high-frequency in situ observations of HFCs and ongoing observations are crucially important to assess the historical and future emission evolution of HFCs under the Montreal Protocol.