Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models

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 (SO<sub>2</sub>) emissions from China. We find that the models differ by up...

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Main Authors: M. Kasoar, A. Voulgarakis, J.-F. Lamarque, D. T. Shindell, N. Bellouin, W. J. Collins, G. Faluvegi, K. Tsigaridis
Format: Article
Language:English
Published: Copernicus Publications 2016-08-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/16/9785/2016/acp-16-9785-2016.pdf
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author M. Kasoar
A. Voulgarakis
J.-F. Lamarque
D. T. Shindell
N. Bellouin
W. J. Collins
G. Faluvegi
G. Faluvegi
K. Tsigaridis
K. Tsigaridis
author_facet M. Kasoar
A. Voulgarakis
J.-F. Lamarque
D. T. Shindell
N. Bellouin
W. J. Collins
G. Faluvegi
G. Faluvegi
K. Tsigaridis
K. Tsigaridis
author_sort M. Kasoar
collection DOAJ
description 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 (SO<sub>2</sub>) 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 SO<sub>2</sub> 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 SO<sub>2</sub> 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.
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spelling doaj.art-e8aa86d777d246eebc67a62f31d6873d2022-12-22T02:55:06ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242016-08-01169785980410.5194/acp-16-9785-2016Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate modelsM. Kasoar0A. Voulgarakis1J.-F. Lamarque2D. T. Shindell3N. Bellouin4W. J. Collins5G. Faluvegi6G. Faluvegi7K. Tsigaridis8K. Tsigaridis9Department of Physics, Imperial College London, London, UKDepartment of Physics, Imperial College London, London, UKAtmospheric Chemistry Observations and Modeling and Climate and Global Dynamics Laboratories, National Center for Atmospheric Research, Boulder, CO, USANicholas School of the Environment, Duke University, Durham, NC, USADepartment of Meteorology, University of Reading, Reading, UKDepartment of Meteorology, University of Reading, Reading, UKCenter for Climate Systems Research, Columbia University, New York, NY, USANASA Goddard Institute for Space Studies, New York, NY, USACenter for Climate Systems Research, Columbia University, New York, NY, USANASA Goddard Institute for Space Studies, New York, NY, USAWe 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 (SO<sub>2</sub>) 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 SO<sub>2</sub> 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 SO<sub>2</sub> 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.https://www.atmos-chem-phys.net/16/9785/2016/acp-16-9785-2016.pdf
spellingShingle M. Kasoar
A. Voulgarakis
J.-F. Lamarque
D. T. Shindell
N. Bellouin
W. J. Collins
G. Faluvegi
G. Faluvegi
K. Tsigaridis
K. Tsigaridis
Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models
Atmospheric Chemistry and Physics
title Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models
title_full Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models
title_fullStr Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models
title_full_unstemmed Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models
title_short Regional and global temperature response to anthropogenic SO<sub>2</sub> emissions from China in three climate models
title_sort regional and global temperature response to anthropogenic so sub 2 sub emissions from china in three climate models
url https://www.atmos-chem-phys.net/16/9785/2016/acp-16-9785-2016.pdf
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