Solar Geoengineering: What Role Could It Play in Climate Policy?

Solar geoengineering, the deliberate injection of aerosols into the stratosphere, seeks to partially compensate for the climate impacts caused by greenhouse gases by reflecting a small fraction of sunlight back to space. Solar geoengineering may have an important role as a supplement, not a substitute, for emissions cuts. This session will describe these potential benefits, and the physical science involved, as well as the risks, which could include ozone loss, reduced precipitation, increased diffuse shortwave radiation, perturbations to large-scale atmospheric circulation, and direct toxicity of the aerosols themselves. Additionally, solar geoengineering poses significant governance challenges. One major sociopolitical risk is the possibility that the prospect of solar geoengineering will cause relevant actors to reduce their efforts to cut emissions. Other challenges are that in seeking a “global thermostat,” researchers and policymakers will have to confront problematic questions about when and how it should be used, who is entitled to make implementation decisions, how disputes should be resolved, and how to compensate for real or perceived damages. As speakers will discuss, there are no obvious answers to any of these questions, and finding adequate ways to address them will require insights from a broad range of natural and social sciences.