Reviewer 2 does geoengineering

In this episode of Reviewer 2 Does Geoengineering, @geoengineering1 speaks with Daniel Lashof of the World Resources Institute (WRI) about the internationalisation of carbon dioxide removal markets and the policies needed to scale carbon removal globally. Lashof discusses how US policy support, including the 45Q tax credit and the 2022 Inflation Reduction Act, helped stimulate investment in carbon removal startups, and how subsequent policy reversals under President Trump have affected market growth and corporate demand. Against this backdrop, the conversation explores how governments elsewhere are developing policy frameworks to support CDR, including Denmark’s Group of Negative Emitters, Sweden’s €3 billion bio-CCS reverse auction, the EU’s carbon removal certification framework and Brazil’s emerging carbon market. The discussion also examines measurement, reporting and verification challenges across direct air capture, enhanced rock weathering, ocean-based CDR and biomass-based approaches, alongside sustainability concerns, the controversies surrounding Drax and the risk of unintended incentives, as illustrated by biofuels. Drawing on WRI’s analysis of international CDR policies, Lashof considers how government procurement, tax credits, research funding, certification standards and predictable long-term policies can strengthen both supply and demand. Finally, he discusses what it would take to scale CDR to gigaton levels, highlighting the potential role of mandatory policies that require polluters to pay for durable carbon removal. He emphasises that CDR must complement, rather than substitute for, rapid emissions reductions in meeting global climate goals. Article Discussed: Lashof, D., Riedl, D., & Schumer, C. As the US Carbon Dioxide Removal Market Retreats, Other Governments Step Up. World Resources Institute (WRI). https://www.wri.org/insights/carbon-dioxide-removal-policies-frameworks

Cornell University geochemist Louis Derry joins @geoengineering1 to discuss a fundamental question for enhanced rock weathering: how much of the alkalinity generated in soils actually makes it through watersheds to the ocean? Derry argues that many studies and commercial MRV approaches focus on the top 10-30 cm of soil, potentially missing critical processes along the full flow path, including ion exchange in acidic soils, secondary clay formation, acidity generation and carbonate precipitation, which can reduce alkalinity export before it reaches streams. He highlights hydrological constraints, arguing that limited runoff and realistic alkalinity concentrations make proposed removal rates of 5-10 tonnes of CO₂ per hectare per year difficult to achieve across typical row-crop regions. Drawing on natural basaltic catchments and experimental systems, he points to estimates of global basalt weathering of ~0.1-0.2 Gt CO₂/yr, suggesting gigaton-scale enhanced weathering projections are overoptimistic, with co-benefits more credible than large-scale CDR. Paper Discussed: Derry, L. A., Maher, K., & Chadwick, O. A. (2026). Critical zone processes limit alkalinity export from natural basaltic systems. Nature, 1–6. https://doi.org/10.1038/s41586-026-10936-3 Related article: Limitations on carbon dioxide uptake by enhanced weathering - Springer Nature Research Communities https://communities.springernature.com/posts/limitations-on-carbon-dioxide-uptake-by-enhanced-weathering

@geoengineering1 interviews Claudia Elisabeth Wieners and Meike de Nooij about extratropical cyclones, the winter storm systems that drive much of the weather variability and many extreme wind and precipitation events in the midlatitudes, and how stratospheric aerosol injection (SAI) could alter their tracks and associated weather extremes. They discuss what makes extratropical cyclones different from tropical cyclones, why SAI could affect storm tracks, and what their high-resolution modelling reveals about changes in the North Atlantic and North Pacific. The conversation explores why SAI is not simply an “undo button” for global warming, with regional shifts in storm tracks and different responses in precipitation and wind extremes even when global temperatures are brought closer to present-day levels. Claudia and Meike also discuss the uncertainties surrounding their findings, the need for further high-resolution modelling, and the broader challenges of assessing and governing SAI. They argue that governments and policymakers need to take SAI seriously by supporting rigorous research and considering how any future deployment should be carefully governed. Paper discussed: de Nooij, M., de Jong, J., Baatsen, M. L., & Wieners, C. E. (2026). Extratropical Cyclone and Storm track Responses to Stratospheric Aerosol Injection in High-Resolution CESM Simulations. EGUsphere [preprint], 1-26. https://doi.org/10.5194/egusphere-2026-4133

Could reducing sunlight to cool the planet also affect mental health? @geoengineering1 interviews Shinsuke Tanaka about new research examining the link between sunlight and suicide and what it could mean for solar radiation management (SRM). Using nearly three decades of U.S. county-month data, Tanaka and colleagues find that sustained reductions in sunlight significantly increase suicide rates. They estimate that a 1.5°C SRM scenario could result in around 3,810 additional U.S. suicides between 2030 and 2100 from reduced sunlight alone, or 16,320 when temperature effects are included. The conversation also covers the difference between seasonal correlations and causal effects, possible biological and behavioral mechanisms, and the challenges of applying U.S.-based findings globally. Paper Discussed: Tanaka, S., & Matsubayashi, T. (2026). Clouding the mind? Assessing the suicide impacts of solar radiation management in the United States. The Japanese Economic Review, 1-21. https://link.springer.com/article/10.1007/s42973-026-00273-5

How much carbon can enhanced rock weathering actually remove? In this episode, @geoengineering1 talks with Tyler Kukla of CarbonPlan about how assumptions about rock surface roughness can dramatically change enhanced weathering estimates. They discuss why surface area is critical to weathering rates, how commonly used roughness calculations can overestimate available surface area, and what this means for modeled CO₂ removal. The conversation also explores the differences between surface-area- and water-transport-limited weathering, the challenges of scaling enhanced weathering, and why better measurements are needed to constrain models. The discussion is based on Tyler Kukla et al.’s CarbonPlan article, How Surface Roughness Scaling Can Mislead Enhanced Weathering Predictions. https://carbonplan.org/research/modeling-bytes-02-roughness