Future benefits of emission controls in mitigating climate-driven regional transport of PM2.5 in China

Abstract Regional transport is equally significant to local sources in contributing to PM2.5 pollution and associated environmental inequality. In the context of future climate change, the effect of the responses of regional transport to the warming climate and controlling emissions has not been thoroughly investigated. Here we establish cross-province PM2.5 source-receptor matrix in China in 2015 baseline and two climate pathways in 2050s (SSP585 and SSP126), using Community Multi-scale Air Quality model embedded with the Integrated Source Apportionment Method. Results suggest that across-regional transport contributes 36.1 % - 62.3 % of PM2.5 in five severely polluted regions, which is even more important compared to inner transport within the target region (3.8 % - 19.4 %), especially in Chuanyu and Fenwei regions which are polluted by large PM2.5 transport (over 50 %) from outside regions. Such results imply that joint-control policy should not only focus on neighboring provinces. Controlling pollutant emission is undoubtedly reduced the concentration of PM2.5 regional transport (by -5.25 µg/m3 on average), largely exceeding the influence from the meteorological fluctuations (by -0.82 µg/m3 on average) driven by the climate change in 2050s. On the other hand, future controlled pollutant emissions proved that strengthen across-regional transport with an enlarged relative contribution to total PM2.5 concentration (8.46%) in 2050, along with a decreased contribution from local sources (8.54%). Therefore, environmental inequality issue should be pay more attention in the context of the reduction of pollution and carbon emissions.