Characteristics of a Solar Geoengineering Deployment: Considerations for Governance

Consideration of solar geoengineering as a potential response to climate change will demand complex decisions. These include not only the choice to deploy or not, but decisions regarding how to deploy, and ongoing decision making throughout deployment. However, relatively little attention has been paid to envisioning what a solar geoengineering deployment would look like in order to clarify what types of decisions would need to be made. We examine the science of geoengineering to ask how it might influence governance considerations, while consciously refraining from making specific recommendations. The focus here is on a hypothetical deployment (and beyond) rather than research governance. Geoengineering can be designed to trade off different outcomes, requiring an explicit specification of multivariate goals. Thus, we initially consider the complexity surrounding a decision to deploy. Next, we discuss the on-going decisions that would be needed across multiple time-scales. Some decisions are inherently slow, limited by detection and attribution of climate effects in the presence of natural variability. However, there is also a need for decisions that are inherently fast relative to political time-scales: effectively managing some uncertainties would require frequent adjustments to the geoengineered forcing in response to observations. We believe that this exercise can lead to greater clarity in terms of future governance needs by articulating key characteristics of a hypothetical deployment scenario.