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© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 04 Feb 2020

Submitted as: research article | 04 Feb 2020

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A revised version of this preprint is currently under review for the journal ACP.

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

Robert J. Allen1, Steven Turnock2, Pierre Nabat3, David Neubauer4, Ulrike Lohmann4, Dirk Olivie5, Naga Oshima6, Martine Michou3, Tongwen Wu7, Jie Zhang7, Toshihiko Takemura8, Michael Schulz5, Kostas Tsigaridis9, Susanne E. Bauer9, Louisa Emmons10, Larry Horowitz11, Vaishali Naik11, Twan van Noije12, Tommi Bergman12,13, Jean-Francois Lamarque14, Prodromos Zanis15, Ina Tegen16, Daniel M. Westervelt17, Philippe Le Sager12, Peter Good2, Sungbo Shim18, Fiona O'Connor2, Dimitris Akritidis15, Aristeidis K. Georgoulias15, Makoto Deushi6, Lori T. Sentman11, Shinichiro Fujimori19,20,21, and William J. Collins22 Robert J. Allen et al.
  • 1Department of Earth and Planetary Sciences, University of California Riverside, Riverside, CA, 92521, USA
  • 2Met Office Hadley Centre, Exeter, UK
  • 3Centre National de Recherches Meteorologiques (CNRM), Universite de Toulouse, Meteo-France, CNRS, Toulouse, France
  • 4Institute of Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
  • 5Norwegian Meteorological Institute, Oslo, Norway
  • 6Meteorological Research Institute, Japan Meteorological Agency
  • 7Beijing Climate Center, China Meteorological Administration, Beijing, China
  • 8Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan
  • 9Center for Climate Systems Research, Columbia University, NASA Goddard Institute for Space Studies, USA
  • 10Atmospheric Chemistry Observations and Modelling Lab, National Center for Atmospheric Research, Boulder, CO, USA
  • 11DOC/NOAA/OAR/Geophysical Fluid Dynamics Laboratory. Biogeochemistry, Atmospheric Chemistry, and Ecology 10 Division, Princeton, USA
  • 12Royal Netherlands Meteorological Institute, De Bilt, the Netherlands
  • 13Finnish Meteorological Institute, Helsinki, Finland
  • 14NCAR/UCAR, Boulder, CO, USA
  • 15Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece
  • 16Leibniz Institute for Tropospheric Research, Leipzig, Germany
  • 17Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
  • 18National Institute of Meteorological Sciences, Seogwipo-si, Jeju-do, Korea
  • 19Department of Environmental Engineering, Kyoto University, C1-3 361, Kyotodaigaku Katsura, Nishikyoku, Kyoto city, Japan
  • 20Center for Social and Environmental Systems Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan
  • 21International Institute for Applied System Analysis (IIASA), Schlossplatz 1, A-2361, Laxenburg, Austria
  • 22Department of Meteorology, University of Reading, Reading, RG6 6BB, UK

Abstract. Over the next few decades, policies that optimally address both climate change and air quality are essential. Although targeting near-term climate forcers (NTCFs), defined here as aerosols, tropospheric ozone and precursor gases (but not methane), should improve air quality, NTCF reductions will also impact climate. How future policies affect the abundance of NTCFs and their impact on climate and air quality remains uncertain. Here, we quantify the 2015–2055 climate and air quality effects of non-methane NTCFs using state-of-the-art chemistry-climate model simulations conducted for the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). Simulations are driven by two future scenarios featuring similar increases in greenhouse gases (GHGs) but with weak versus strong levels of air quality control measures. Unsurprisingly, we find significant improvements in air quality under NTCF mitigation (strong versus weak air quality controls). Surface ozone (O3) and fine particulate matter (PM2.5) decrease by −15 % and −25 %, respectively, over global land surfaces, with larger reductions in some regions including south and southeast Asia. Non-methane NTCF mitigation, however, leads to additional climate change due to the removal of aerosol which causes a net warming effect, including global mean surface temperature and precipitation increases of 0.24 K and 1.1 %, respectively, with similar increases in extreme weather indices. Regionally, the largest warming and wetting trends occur over Asia, including central and north Asia (0.56 K and 2.1 %), south Asia (0.48 K and 4.6 %) and east Asia (0.44 K and 4.7 %). Relatively large warming and wetting of the Arctic also occurs at 0.41 K and 2.1 %, respectively. Similar surface warming occurs in model simulations with aerosol-only mitigation, implying weak cooling due to ozone reductions. Our findings suggest that future policies that aggressively target non-methane NTCF reductions will improve air quality, but will lead to additional surface warming, particularly in Asia and the Arctic. Policies that address other NTCFs including methane, as well as carbon dioxide emissions, must also be adopted to meet mitigation goals.

Robert J. Allen et al.

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Robert J. Allen et al.

Robert J. Allen et al.


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