Long-term Variability in Black Carbon Emissions Constrained by Gap-filled Absorption Aerosol Optical Depth and Associated Premature Mortality in China

Abstract. Black carbon (BC) plays an important role in air quality, public health, and climate, while its long-term variations in emissions and health effect were insufficiently understood for China. Here, we present the spatiotemporal evolution of BC emissions and the associated premature mortality in China during 2000–2020 based on an integrated framework combining satellite observations, a machine learning technique, a “top-down” inversion approach, and an exposure-response model. We found that the “bottom-up” approach likely underestimated BC emissions, particularly in less developed western and remote areas. Pollution controls were estimated to reduce the annual BC emissions by 26 % during 2010–2020, reversing the 8 % growth during 2000–2010. BC emissions in the main coal-producing provinces declined by 2010 but rebounded afterwards. By contrast, provinces with higher economic and urbanization levels experienced emission growth (0.05–0.10 Mg/km²/yr) by 2010 and declined greatly (0.07–0.23 Mg/km²/yr) during 2010–2020. The national annual BC-associated premature mortality ranged between 733,910 (95 % confidence interval: 676,790–800,250) and 937,980 cases (864,510–1,023,400) for different years. The changing BC emissions contributed 78,590 cases (72,520–85,600) growth within 2000–2005 and 133,360 (123,150–145,180) reduction within 2010–2015. Strategies differentiated by region are needed for further reducing BC emissions and its health and climate impacts.