The Influence of Climate Change and Human Activities on the Future Air Quality in the Beijing-Tianjin-Hebei Region of China

As the Beijing-Tianjin-Hebei (BTH) region of China is one of the key areas with PM_2.5 air pollution and various control policies, to project the future air quality in this region under different climate scenarios and emission scenarios is of great significance. Under the comprehensive considering meteorology and anthropogenic emission, the target accessibility of 35 µg/m³ annual mean PM_2.5 concentration (the Interim Target-1 by World Health Organization) in 2030, similar to the command of the carbon emissions peak and carbon neutrality, will be analyzed based on the sensitivity experiments. This study explored and quantified the influence of climate change and anthropogenic emission on the future air quality in BTH region under the future climate scenario RCP8.5, RCP4.5, and RCP2.6 with the baseline and reduced emission inventory (Base and EIT1 scenarios). The future air quality research modeling system including global climate model BNU-ESM, regional meteorological model WRF, emission process model SMOKE and air quality model CMAQ is utilized. The BNU-ESM provided the global meteorological field, and the more specific meteorological data simulated by WRF using dynamical downscaling method were adopted to drive the SMOKE model to calculate emission inventory and CMAQ model to generate air pollutant results. The results show that the future PM_2.5 concentrations over BTH still present the seasonal variation, higher in winter and lower in summer. Moreover, the annual PM_2.5 concentrations under various climate scenarios and under Base emission scenario are almost consistent, about 40µg/m³. However, the annual PM_2.5 concentrations over BTH under the identical RCP4.5 climate scenario and under diverse emission scenario shows huge differences. The annual PM_2.5 concentrations under EIT1 emission scenario is 37.5% less than the value under Base emission scenario and could achieve the annual target of 35µg/m³. Besides, the shape of high PM_2.5 concentrations follows the area with high emission inventory. In a word, the future PM_2.5 concentrations over BTH region is highly related to anthropogenic emission by human activities, while the climate change in 2030 has little impact on the future air quality over BTH region. That indicates emission reduction is significantly required to achieve the new Chinese PM_2.5 target in 2030.