[A-AS11] Aerosol impacts on air quality, climate system, and our society

[AAS11-09] Dependency of surface air temperature change by sulfate aerosols on CO₂ concentration

*Toshihiko Takemura¹ (1.Research Institute for Applied Mechanics, Kyushu University)

Keywords:aerosols, climate change, temperature, greenhouse gases, climate model, feedback

Sulfate aerosols are estimated to mitigate global warming through aerosol-radiation interactions by scattering solar radiation and through aerosol-cloud interactions enhancing it by cloud droplets. Under the present situation in which emissions of anthropogenic SO₂, a primary precursor of sulfate aerosol, are decreasing and, on the other hand, atmospheric CO₂ concentrations are increasing, it is anxious about accelerating global warming. In the previous study, a change in surface air temperature with perturbed SO₂ and black carbon emissions (factors of 0.0, 0.1, 0.3, 0.5, 0.8, 1.5, and 2.0 relative to present emissions) were analyzed using an atmosphere-ocean general circulation model coupled with an aerosol process model, MIROC-SPRINTARS (Takemura and Suzuki, 2019). In this study, extended experiments were performed with CO₂ concentrations both of present (369 ppm, recorded in 2000) and double (738 ppm, close to SSP3-7.0 scenario for 2080) for each SO₂ emission factor. The experimental results show that reducing SO₂ emission at high CO₂ concentration brings an enhanced increase in surface air temperature. The warming is especially strong over land at the mid- and high- latitudes in the Northern Hemisphere because of an larger increase in water vapor that is a greenhouse gas, a weaker increase in liquid water path, and stronger ice-albedo feedback under the higher CO₂ concentration.

Reference: Takemura, T., and K. Suzuki, Sci. Rep., 9, 2019, doi:10.1038/s41598-019-41181-6.