Geoengineering as a design problem

• Published in: Earth System Dynamics
• Main Authors: Kravitz, Ben, MacMartin, Douglas G., Wang, Hailong, Rasch, Philip J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: European Geosciences Union 2016
• Subjects: Arctic; Pacific
• Online Access: https://doi.org/10.5194/esd-7-469-2016

Understanding the climate impacts of solar geoengineering is essential for evaluating its benefits and risks. Most previous simulations have prescribed a particular strategy and evaluated its modeled effects. Here we turn this approach around by first choosing example climate objectives and then designing a strategy to meet those objectives in climate models. There are four essential criteria for designing a strategy: (i) an explicit specification of the objectives, (ii) defining what climate forcing agents to modify so the objectives are met, (iii) a method for managing uncertainties, and (iv) independent verification of the strategy in an evaluation model. We demonstrate this design perspective through two multi-objective examples. First, changes in Arctic temperature and the position of tropical precipitation due to CO_2 increases are offset by adjusting high-latitude insolation in each hemisphere independently. Second, three different latitude-dependent patterns of insolation are modified to offset CO_2-induced changes in global mean temperature, interhemispheric temperature asymmetry, and the Equator-to-pole temperature gradient. In both examples, the "design" and "evaluation" models are state-of-the-art fully coupled atmosphere–ocean general circulation models. © 2016 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Received: 06 Aug 2015 – Published in Earth Syst. Dynam. Discuss.: 08 Sep 2015; Revised: 18 Mar 2016 – Accepted: 10 May 2016 – Published: 24 May 2016. We thank the reviewers and the editor for thorough comments that greatly improved the manuscript. The Pacific Northwest National Laboratory is operated for the US Department of Energy by Battelle Memorial Institute under contract DE-AC05-76RL01830. CESM simulations were performed using PNNL institutional computing resources. GISS ModelE2 simulations were supported by the NASA High-End Computing (HEC) Program through the NASA Center for Climate Simulation (NCCS) at Goddard Space Flight Center. ...