This article adds conceptual discipline to a well‐rehearsed but largely intuitive argument within the climate engineering community that carbon dioxide removal (CDR) and solar radiation management (SRM) should be treated separately – ‘split’ rather than ‘lumped’ – in policy discussions. Specifically, we build the first, theoretically derived argument for ‘splitting’. We do this by engaging a set of theoretical insights from the international relations literature, having to do with the relationship between problem structure and institutional design. Centrally, we apply some key elements of problem structure – which allows us to compare policy issues along variables such as geographic scope, costs, and actor number and asymmetries – to the cases of SRM and CDR. By analyzing their problem structures, we demonstrate that SRM and CDR are different in ways that are likely to yield different state preferences for institutional design, and thus policy proposals that split SRM and CDR are more likely to be adopted by states. In short, we construct a theoretical argument for ‘splitting’ SRM and CDR governance in global policy discussions.
- Rather than ‘lumping’ disparate technologies under the umbrella term ‘geoengineering’, solar radiation management (SRM) and carbon dioxide removal (CDR) should be considered separately – ‘split’ – in policy forums, including at the UN Environment Assembly and the Convention on Biological Diversity.
- Solar radiation management and carbon dioxide removal have different problem structures and thus will likely be governed by different types of institutions, at least in the near term. States are more likely to favor decentralized, flexible agreements for SRM research governance as well as for CDR. In contrast, states are likely to favor more centralized agreements with wide scope for SRM deployment.
- Governance of SRM and CDR will need to become more tightly coupled if and when SRM or CDR options mature and become ready for deployment at scale. This will require a new or existing international institution to play a strong coordinating role in the future.
- States are more likely to favor: decentralized, flexible agreements for SRM research governance; centralized agreements with wide scope for SRM deployment; and flexible agreements for CDR.