Assessment report on climate interventions governance strategies

This report brings together four studies that address critical questions at the intersection of solar geoengineering, carbon dioxide removal (CDR), and climate policy. The first study examines public perceptions of stratospheric aerosol injection (SAI) in Mexico, the United States, and the United Kingdom using nationally representative surveys. Results show that support is highest in Mexico, while information framing has only limited effects. Universities are viewed as more legitimate actors than start-ups, though overall perceptions of risks and benefits remain similar across countries.

The second study focuses on CDR, using surveys of 800 participants each in five countries (Brazil, Kenya, Germany, the United States, and China). Support varies strongly across countries, with Brazil and Kenya most supportive and Germany least supportive of direct air capture (DAC) and enhanced rock weathering (ERW). Across all countries, afforestation and reforestation attract the strongest support, while DAC is consistently the least favoured. Policies emphasizing nature protection and mitigation are better received than those involving taxation.

The third study develops a novel modelling framework combining an Earth system emulator with a country-level integrated assessment model to analyse regional heterogeneity in SAI impacts. Cooperative global governance delivers welfare improvements, while unilateral deployment by major emitters risks asymmetric strategies with harmful side effects on equatorial and tropical regions, highlighting the governance risks of uncoordinated action.

Finally, the fourth study explores intertemporal financing mechanisms for negative emissions. Using a stylized integrated assessment model, it shows how different 
pricing rules affect mitigation pathways, wealth transfers across generations, and ethical considerations surrounding market-based incentives for CDR.