Impacts of greenhouse gases and anthropogenic aerosols changes on surface air temperature in East Asia under different post-pandemic period emission scenarios

Abstract

In order to know how surface air temperature (SAT) changes in East Asia under different emission scenarios after the COVID-19 outbreak, we investigated the impacts of greenhouse gases (GHGs) and anthropogenic aerosols changes on SAT in East Asia by using the aerosol-climate coupled model BCC-AGCM 2.0_CUACE/Aero, combining with the post-pandemic emission scenarios proposed by Covid multi-Earth system model intercomparison project (CovidMIP scenarios for short, including fossil-fueled recovery, moderate green stimulus, strong green stimulus, hereinafter as FFF, MGG, SGG, respectively). We assessed the impacts of changes in GHGs and anthropogenic aerosols together and separately on SAT in East Asia and its typical subregions during 2020–2050. The results show that by mid-21st-century, SAT in East Asia will increase by 0.81 ± 0.083 °C under Baseline (same as SSP2-4.5 scenario), i.e., SAT difference between 2045–2050 and 2020–2025), and there will be more intense warming in all the three scenarios in East Asia, in which the largest SAT difference (SAT-d) compared to Baseline is 0.33 ± 0.11 °C under SGG and the smallest SAT-d is 0.07 ± 0.14 °C under FFF. To further explore the mechanism of these SAT-d, we analyzed the trend of surface longwave and shortwave net radiation flux driven by GHGs and anthropogenic aerosols there. It is found that in early period (2020–2035), the role of aerosol changes is bigger than that of GHG changes in dominating SAT-d, particularly sulfate, whose reduction will become the main contributor to SAT-d by affecting the net solar flux at surface. In later period (2036–2050), because of GHGs’ longer atmospheric lifetime than aerosols, the role of decreasing GHGs concentrations will determine the drop in SAT-d through affecting the net longwave flux at surface.