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: English
• Published: European Geosciences Union 2016
• Subjects: Arctic
• Online Access: https://authors.library.caltech.edu/69449/; https://authors.library.caltech.edu/69449/1/esd-7-469-2016.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20160804-132109803

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.