Improved ecosystem productivity in China driven by declining aerosols and surface ozone

Severe air pollution reduces ecosystem carbon assimilation by damaging vegetation with ozone (O₃) and altering climate through aerosol effects, thereby exacerbating global warming. In response, China implemented the Clean Air Action (CAA) plan in 2013 to reduce anthropogenic emissions. Here we assessed the impact of CAA-induced air pollution reductions on net primary productivity (NPP) in China during 2014-2020 using multiple measurements, process-based models, and machine learning algorithms. The CAA plan led to a national NPP increase of 26.3±27.9 Tg C yr^-1, with 20.1±10.9 Tg C yr^-1 attributed to aerosol reductions, mainly driven by enhanced light availability from decreased black carbon and increased precipitation due to weakened aerosol climatic effects. The impact of O₃ amelioration became more significant over time, surpassing the effects of aerosol reduction by 2020. Two machine learning models showed similar NPP recoveries of 42.8±26.8 Tg C yr^-1 and 43.4±30.1 Tg C yr^-1. Our study highlights significant carbon gains from controlling aerosols and surface O₃, underscoring the co-benefits of air pollution regulation for public health and carbon neutrality in China.