Using the fast impact of anthropogenic aerosols on regional land temperature to constrain aerosol forcing

Creators: Shen, Zhaoyi; Ming, Yi; Held, Isaac M.

Abstract

Anthropogenic aerosols have been postulated to have a cooling effect on climate, but its magnitude remains uncertain. Using atmospheric general circulation model simulations, we separate the land temperature response into a fast response to radiative forcings and a slow response to changing oceanic conditions and find that the former accounts for about one fifth of the observed warming of the Northern Hemisphere land during summer and autumn since the 1960s. While small, this fast response can be constrained by observations. Spatially varying aerosol effects can be detected on the regional scale, specifically warming over Europe and cooling over Asia. These results provide empirical evidence for the important role of aerosols in setting regional land temperature trends and point to an emergent constraint that suggests strong global aerosol forcing and high transient climate response.

Additional Information

© 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). Submitted 2 March 2020; Accepted 24 June 2020; Published 5 August 2020. We thank T. Knutson and D. Paynter for helpful comments on an earlier draft. Z.S. is funded during the early stage of the project by the National Oceanic and Atmospheric Administration and U.S. Department of Commerce under award NA14OAR4320106. The statements, findings, conclusions, and recommendations are those of the authors and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration or the U.S. Department of Commerce. Author contributions: All authors collaboratively designed the study and wrote the manuscript. Z.S. carried out the model simulations and conducted the analysis. The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. BEST was downloaded from the Berkeley Earth website (http://berkeleyearth.org/). Model simulations are archived at GFDL and are available from the authors upon request. Additional data related to this paper may be requested from the authors.

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