A multi-model assessment of regional climate disparities caused by solar geoengineering

Creators: Kravitz, Ben; MacMartin, Douglas G.; Robock, Alan; Rasch, Philip J.; Ricke, Katharine L.; Cole, Jason N. S.; Curry, Charles L.; Irvine, Peter J.; Ji, Duoying; Keith, David W.; Kristjánsson, Jón Egill; Moore, John C.; Muri, Helene; Singh, Balwinder; Tilmes, Simone; Watanabe, Shingo; Yang, Shuting; Yoon, Jin-Ho

Abstract

Global-scale solar geoengineering is the deliberate modification of the climate system to offset some amount of anthropogenic climate change by reducing the amount of incident solar radiation at the surface. These changes to the planetary energy budget result in differential regional climate effects. For the first time, we quantitatively evaluate the potential for regional disparities in a multi-model context using results from a model experiment that offsets the forcing from a quadrupling of CO2 via reduction in solar irradiance. We evaluate temperature and precipitation changes in 22 geographic regions spanning most of Earthʼs continental area. Moderate amounts of solar reduction (up to 85% of the amount that returns global mean temperatures to preindustrial levels) result in regional temperature values that are closer to preindustrial levels than an un-geoengineered, high CO_2 world for all regions and all models. However, in all but one model, there is at least one region for which no amount of solar reduction can restore precipitation toward its preindustrial value. For most metrics considering simultaneous changes in both variables, temperature and precipitation values in all regions are closer to the preindustrial climate for a moderate amount of solar reduction than for no solar reduction.

Additional Information

© 2014 IOP Publishing. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Received 10 March 2014; revised 27 June 2014; Accepted for publication 1 July 2014; Published 22 July 2014. We thank all participants of the Geoengineering Model Intercomparison Project and their model development teams, CLIVAR/WCRP Working Group on Coupled Modeling for endorsing GeoMIP and the scientists managing the Earth System Grid data nodes who have assisted with making GeoMIP output available. We also thank Kari Alterskjær, Olivier Boucher, Susannah M. Burrows, Sarah Fillmore, James M. Haywood, Andy Jones, Ulrike Niemeier, and Hauke Schmidt for helpful discussions and three anonymous reviewers for their comments. We acknowledge the World Climate Research Programmeʼs Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups for producing and making available their model output. For CMIP the U.S. Department of Energyʼs Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. BK is supported by the Fund for Innovative Climate and Energy Research (FICER). Simulations performed by BK were supported by the NASA High-End Computing (HEC) Program through the NASA Center for Climate Simulation (NCCS) at Goddard Space Flight Center. The Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle Memorial Institute under contract DE-AC05–76RLO 1830. AR is supported by US National Science Foundation grants AGS-1157525 and GEO-1240507. Computer resources for PJR, BS, and JHY were provided by the National Energy Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02–05CH11231. CLC is supported by a Canadian NSERC grant (CRDPJ 403886–10). JEK received funding from the European Unionʼs Seventh Framework Programme through the IMPLICC project (FP7-ENV- 2008–1-226567) and support from the Norwegian Research Councilʼs Programme for Supercomputing (NOTUR) through a grant of computing time. HM was supported by the EuTRACE project, the European Union 7th Framework Programme 785 grant No. 306395. Simulations with the IPSL-CM5 model were supported through HPC resources of [CCT/TGCC/CINES/IDRIS] under the allocation 2012- t2012012201 made by GENCI (Grand Equipement National de Calcul Intensif). DJ and JCM thank all members of the BNU-ESM model group, as well as the Center of Information and Network Technology at Beijing Normal University for assistance in publishing the GeoMIP data set. The National Center for Atmospheric Research is funded by the National Science Foundation. SW was supported by the Innovative Program of Climate Change Projection for the 21st century, MEXT, Japan.

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