International Governance of Solar Geoengineering: Principles and Precedents.

Solar geoengineering (SGE) refers to a set of technological interventions which seek to counteract global warming by reflecting incoming solar radiation. SGE could produce significant benefits by reducing the average global temperature. However, it also poses serious and unpredictable risks at the regional and global level. At present, there are no international agreements directly addressing SGE. My central research question asks what role principles of international environmental law (IEL) can play in filling this gap in the current legal architecture.

The existing literature typically concludes that the role of IEL principles in this area will be marginal. While these principles are widely accepted by states, they vary in their precise formulations, and there is uncertainty about their legal status. These limitations are said to be particularly problematic in relation to SGE, which poses risks of its own while seeking to address those created by climate change. In this context, IEL principles urging precaution, harm prevention, or consideration of equity appear to cut both ways, undermining their ability to provide coherent action guidance. My project will reassess this dominant narrative, over the course of three complementary parts.

Part one will ask to what extent IEL principles can influence States' decisions on SGE deployment, independently of any new international agreement. I will employ doctrinal legal analysis of national and international court decisions to determine the legal status of the principles, as well as exploring avenues for their application and enforcement. This part will require engagement with conflicting methodological approaches for explaining how international law influences state behaviour. Particular emphasis will be placed on the potential influence of the harm prevention principle, which has the most robust legal status and the most determinate and widely accepted content.

Part two will examine the frequently raised but...