Climate Responses to Direct Radiative Forcing of Anthropogenic Aerosols, Tropospheric Ozone, and Long-Lived Greenhouse Gases in Eastern China over 1951-2000

A unified chemistry-aerosol-climate model is applied in this work to compare climate responses to changing concentrations of long-lived greenhouse gases (GHGs, CO2, CH4, N2O), tropospheric O-3, and aerosols during the years 1951-2000. Concentrations of sulfate, nitrate, primary organic carbon (POA), secondary organic carbon (SOA), black carbon (BC) aerosols, and tropospheric O-3 for the years 1950 and 2000 are obtained a priori by coupled chemistry-aerosol-GCM simulations, and then monthly concentrations are interpolated linearly between 1951 and 2000. The annual concentrations of GHGs are taken from the IPCC Third Assessment Report. BC aerosol is internally mixed with other aerosols. Model results indicate that the simulated climate change over 1951-2000 is sensitive to anthropogenic changes in atmospheric components. The predicted year 2000 global mean surface air temperature can differ by 0.8 degrees C with different forcings. Relative to the climate simulation without changes in GHGs, O-3, and aerosols, anthropogenic forcings of SO42-, BC, BC+SO42-, BC+SO42 (-)+POA, BC+SO42- +POA+SOA+NO3-, O-3, and GHGs are predicted to change the surface air temperature averaged over 1971-2000 in eastern China, respectively, by -0.40 degrees C, +0.62 degrees C, +0.18 degrees C, +0.15 degrees C, -0.78 degrees C, +0.43 degrees C, and +0.85 degrees C, and to change the precipitation, respectively, by -0.21, +0.07, -0.03, +0.02, -0.24, -0.08, and +0.10 mm d(-1). The authors conclude that all major aerosols are as important as GHGs in influencing climate change in eastern China, and tropospheric O-3 also needs to be included in studies of regional climate change in China.