Jacob Bronsther & Yangyang Xu discuss their recent paper on the socioeconomic costs of Solar Radiation Modification. While SRM’s direct technical costs appear modest (~$18B/°C cooling), the authors argue that its broader costs are far greater. They estimate that Stratospheric Aerosol Injection could generate between $0 and $809 billion annually in side-effect harms, with potentially higher figures for Marine Cloud Brightening.

The conversation also explores SRM’s reliance on unprecedented global cooperation, the political risks of weather accountability, and the dangers of termination, which could impose major financial costs. They contrast these challenges with large-scale Carbon Dioxide Removal, noting that although CDR entails immense technical expenses, it avoids some of SRM’s political and termination risks.

The discussion highlights the complexity of weighing the full spectrum of costs and benefits when evaluating climate-engineering strategies.

Paper: Bronsther, J., & Xu, Y. (2025). The social costs of solar radiation management. npj Climate Action, 4(1), 69. https://doi.org/10.1038/s44168-025-00273-y

Brian Soden discusses his recent study on injecting absorptive aerosols, such as black carbon, into the upper stratosphere to weaken the CO₂ greenhouse effect.

The conversation addresses the radiative physics underpinning this concept, its potential cooling efficiency relative to conventional scattering aerosols, and associated environmental risks. While model results indicate the method could theoretically be effective, Soden remains sceptical about its practical viability.

Paper: He, H., Soden, B. J., Vecchi, G. A., & Yang, W. (2025). Stratospheric aerosol injection can weaken the carbon dioxide greenhouse effect. Communications earth & environment, 6(1), 485. https://doi.org/10.1038/s43247-025-02466-z

Daniel Bodansky discusses his recent article on the drawbacks of a global moratorium on solar radiation management deployment.

The conversation critiques whether a moratorium is feasible or effective, arguing it could hinder critical research, be difficult to enforce, and unintentionally become a proxy for a permanent ban. Instead, the discussion highlights the need for more research and stronger governance frameworks to better understand and responsibly manage geoengineering.

Article: Biniaz, S., & Bodansky, D. (2025, May 13). Why a global “moratorium” on solar radiation management deployment should get a chilly reception. Just Security. https://www.justsecurity.org/113295/moratorium-srm-deployment-chilly-reception/

Diego Villanueva discusses his paper on mixed-phase regime cloud thinning (MCT). This geoengineering approach involves using ice-nucleating particles to reduce the heat-trapping effects of polar clouds.

Using climate and cloud-resolving models, the study finds MCT could offset up to 25% of polar ocean warming from CO₂ doubling and increase sea ice by 8% in the Arctic and 14% in Antarctica. In the podcast, we discuss the science behind this method, its potential benefits, limitations, and broader implications.

Paper: Villanueva, D., Possner, A., Neubauer, D., Gasparini, B., Lohmann, U., & Tesche, M. (2022). Mixed-phase regime cloud thinning could help restore sea ice. Environmental Research Letters, 17(11), 114057. https://doi.org/10.1088/1748-9326/aca16d