A Precautionary Assessment of Systemic Projections and Promises From Sunlight Reflection and Carbon Removal Modeling.

Climate change is a paradigmatic example of systemic risk. Recently, proposals for large-scale interventions-carbon dioxide removal (CDR) and solar radiation management (SRM)-have started to redefine climate governance strategies. We describe how evolving modeling practices are trending toward optimized and "best-case" projections-portraying deployment schemes that create both technically slanted and politically sanitized profiles of risk, as well as ideal objectives for CDR and SRM as mitigation-enhancing, time-buying mechanisms for carbon transitions or vulnerable populations. As promises, stylized and hopeful projections may selectively reinforce industry and political activities built around the inertia of the carbon economy. Some evidence suggests this is the emerging case for certain kinds of CDR, where the prospect of future carbon capture substitutes for present mitigation. Either of these implications are systemic: explorations of climatic futures may entrench certain carbon infrastructures. We point out efforts and recommendations to forestall this trend in the implementation of the Paris Agreement, by creating more stakeholder input and strengthening political realism in modeling and other assessments, as well as through policy guardrails.