Study On Short-lived Climate Pollutants (SLCPs) Effective Radiative Forcing And Their Effects On Global Climate

Our living environment and the global climate are changing worse due to productivity improvement. It is a challenging issue of reducing the rate of global climate warming. Control carbon emissions and reduction short-lived climate pollutants(including tropospheric ozone, methane and black carbon aerosol, hereinafter referred to as SLCPs) at the same time is an effective method to slow down climate changing in a short period. For the uncertainty of the eventual effect in future climate due to reduction pollutions, further studiesare still needed. An aerosol-climate coupled model system BCC_AGCM2.0.1_CUACE/Aero from National Climate Center of China was used in this work. And the effective radiative forcing(ERF), newly defined by IPCC AR5, was adopted in discussing the radiative forcing and climate response of SLCPs. Key conclusions are as follows:(1)As the simulation result shows, the ERF due to the change in tropospheric ozone concentration from 1850 to 2013 was 0.46 W/m2, thereby causing an increase in the global annual mean surface temperature by 0.36°C and precipitation by 0.02 mm/day. Because of the change in tropospheric ozone concentrations, there was a remarkable increase in the cloud cover in high latitudes of both Northern and Southern Hemispheres, but the cloud cover decreased sharply near 40°N.(2)The ERF due to the change in methane concentration from pre-industrial to 2013 was 0.46 W/m2. Methane concentrationsdid vary with latitude and decrease above the tropopause, and this variation contributed only 2% to the uncertainty in theERF. Because of the change in methane concentrations, the global annual mean surface temperature increasedby 0.31°C and precipitation increased by 0.02 mm/day. And there was a remarkable increase in the cloud cover in high latitudes of both Northern and Southern Hemispheres, and the cloud cover decreased sharply in tropical areas.(3)The ERF due to the changes in both SLCPs and CO2 concentrations inRCP8.5 from 2010 to 2050 was 2.03 W/m2, thereby causing anincrease in the global annual mean surface temperature by 1.95°C. When the concentrations of CO2 and SLCPs were changed separately in RCP8.5, and the ERFs due to these changes were 1.74 W/m2 and 0.16 W/m2, thereby causing increases in the global annual mean surface temperature by 1.72°C and 0.26°C, respectively. The ERF due to the change in SLCPs concentrations in RCP2.6 from 2010 to 2050 was-0.38 W/m2, thereby causing the global annual mean surface temperature changed by-0.2°C; when the concentration of CO2 was changed together in this climate scenario, the global annual mean surface temperature will increase 0.5°C.The ERF due to the change in SLCPs concentrations in RCP4.5 from 2010 to 2050 was-0.22 W/m2, thereby causing the global annual mean surface temperature changed by-0.04°C; when the concentration of CO2 was changed together in this climate scenario, the global annual mean surface temperature will increase 1.08°C. In both climate scenarios of RCP2.6 and RCP4.5, the global warming were decreased.(4) The ERF due to the difference in SLCPs concentrations between RCP4.5 and RCP8.5 of 2050 was 0.46 W/m2, thereby causing a decrease in the global annual mean surface temperature by 0.46°C and precipitation by 0.02 mm/day. Because of the difference in SLCPs concentrations between RCP4.5 and RCP8.5, the cloud cover in high latitudes of both Northern and Southern Hemispheres was increase remarkably. The precipitation changes greatly near equator, and it increased in most of high latitudes.