Future Ozone Changes and Their Impacts on Vegetation and Human Health in China Under the Shared Socio-Economic Pathways

Ozone concentrations in China are increasing in recent years and future changes of ozone and their impacts have attracted much attention. We use global chemical transport model (GEOS-Chem) to simulate the surface ozone concentrations in China in 2020 and 2050 under four Shared Socio-economic Pathways and evaluate the impacts of future ozone pollution on vegetation and premature mortality in four polluted regions (Beijing-Tianjin-Hebei, BTH; Yangtze River Delta, YRD; Pearl River Delta, PRD; Sichuan Basin, SCB) and three major crop growing areas (Huang-Huai-Hai, HHH; Northeast Plain, NEP; middle and lower reaches of Yangtze River, MLRY) in China. The changes of simulated seasonal maximum daily 8-hr average (MDA8) ozone from 2020 to 2050 (-15.5 to +11.9 ppbv) are significant under SSP126 (low forcing pathway) and SSP245 (medium forcing pathway) scenarios in all regions due to large changes of emissions. MDA8 ozone in summer 2050 will be above the WHO guidelines (100 mu g/m3) in BTH, YRD, HHH and MLRY under four scenarios. By 2050, W126 (vegetative ozone exposure index) in summer will be much above the maximum of US secondary standard (21 ppm-h) in HHH under SSP245, SSP370 (medium to high forcing pathway) and SSP585 (high forcing pathway) scenarios, and in MLRY under SSP370 and SSP585 scenarios. Annual ozone-related deaths for people over 30 years old will mainly decrease in four polluted areas from 2020 to 2050 under SSPs scenarios, but only increase much under SSP245 scenario in BTH (+3.1 to +4.2 thousand) and YRD (+1.1 to +1.6 thousand). With the development of industrialization and urbanization, ozone pollution in China has become increasingly serious. Ozone pollution is harmful to vegetation and human health and thus future ozone in China and its impacts have attracted much attention. We use global chemical transport model to simulate ozone concentrations in 2020 and 2050 under four emission scenarios and then quantify the effects of future ozone pollution on premature mortality and vegetation in four polluted regions and three major crop growing areas in China. Seasonal MDA8 ozone concentrations and vegetative ozone exposure index (W126) change much from 2020 to 2050 under low and medium forcing pathways due to large changes of emissions. Due to ozone pollution, vegetation in summer 2050 will be at high risk in Huang-Huai-Hai region under medium to high and high forcing pathways. Ozone-related deaths will mainly decrease under future emission scenarios in four polluted areas by 2050, but increase much under medium forcing pathway in Beijing-Tianjin-Hebei and Yangtze River Delta regions. MDA8 ozone in summer 2050 will be above WHO guideline of 100 mu g/m3 in Beijing-Tianjin-Hebei and Yangtze River Delta under four SSPs Vegetative ozone exposure index will be above US secondary standard of 21 ppm-h in Huang-Huai-Hai under SSP370 and SSP585 in summer 2050 Mortality will mainly reduce by 2050 in four areas under SSPs, but increase in Beijing-Tianjin-Hebei and Yangtze River Delta under SSP245