Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 9785-9804, 2016
https://doi.org/10.5194/acp-16-9785-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
04 Aug 2016
Regional and global temperature response to anthropogenic SO2 emissions from China in three climate models
Matthew Kasoar1, Apostolos Voulgarakis1, Jean-François Lamarque2, Drew T. Shindell3, Nicolas Bellouin4, William J. Collins4, Greg Faluvegi5,6, and Kostas Tsigaridis5,6 1Department of Physics, Imperial College London, London, UK
2Atmospheric Chemistry Observations and Modeling and Climate and Global Dynamics Laboratories, National Center for Atmospheric Research, Boulder, CO, USA
3Nicholas School of the Environment, Duke University, Durham, NC, USA
4Department of Meteorology, University of Reading, Reading, UK
5Center for Climate Systems Research, Columbia University, New York, NY, USA
6NASA Goddard Institute for Space Studies, New York, NY, USA
Abstract. We use the HadGEM3-GA4, CESM1, and GISS ModelE2 climate models to investigate the global and regional aerosol burden, radiative flux, and surface temperature responses to removing anthropogenic sulfur dioxide (SO2) emissions from China. We find that the models differ by up to a factor of 6 in the simulated change in aerosol optical depth (AOD) and shortwave radiative flux over China that results from reduced sulfate aerosol, leading to a large range of magnitudes in the regional and global temperature responses. Two of the three models simulate a near-ubiquitous hemispheric warming due to the regional SO2 removal, with similarities in the local and remote pattern of response, but overall with a substantially different magnitude. The third model simulates almost no significant temperature response. We attribute the discrepancies in the response to a combination of substantial differences in the chemical conversion of SO2 to sulfate, translation of sulfate mass into AOD, cloud radiative interactions, and differences in the radiative forcing efficiency of sulfate aerosol in the models. The model with the strongest response (HadGEM3-GA4) compares best with observations of AOD regionally, however the other two models compare similarly (albeit poorly) and still disagree substantially in their simulated climate response, indicating that total AOD observations are far from sufficient to determine which model response is more plausible. Our results highlight that there remains a large uncertainty in the representation of both aerosol chemistry as well as direct and indirect aerosol radiative effects in current climate models, and reinforces that caution must be applied when interpreting the results of modelling studies of aerosol influences on climate. Model studies that implicate aerosols in climate responses should ideally explore a range of radiative forcing strengths representative of this uncertainty, in addition to thoroughly evaluating the models used against observations.

Citation: Kasoar, M., Voulgarakis, A., Lamarque, J.-F., Shindell, D. T., Bellouin, N., Collins, W. J., Faluvegi, G., and Tsigaridis, K.: Regional and global temperature response to anthropogenic SO2 emissions from China in three climate models, Atmos. Chem. Phys., 16, 9785-9804, https://doi.org/10.5194/acp-16-9785-2016, 2016.
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Short summary
Computer models are our primary tool to investigate how fossil-fuel emissions are affecting the climate. Here, we used three different climate models to see how they simulate the response to removing sulfur dioxide emissions from China. We found that the models disagreed substantially on how large the climate effect is from the emissions in this region. This range of outcomes is concerning if scientists or policy makers have to rely on any one model when performing their own studies.
Computer models are our primary tool to investigate how fossil-fuel emissions are affecting the...
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