Enhanced Weathering

Description

Removing carbon dioxide (CO2) from the atmosphere is needed to keep global warming below 2 oC. A promising CO2 removal approach is enhanced rock weathering (ERW).  It already has commercial investment and pilot-scale deployment. Weathering occurs when silicate or carbonate rocks are crushed and spread on fields where the rock reacts with CO2 and water to generate a dissolved form of inorganic carbon called bicarbonate. Successful CO2 removal requires generated bicarbonate to travel from agricultural fields through rivers into the ocean. Once in the ocean, bicarbonate will stay dissolved in water and out of the atmosphere for a period of >100,000 years. However, in rivers, on the way to the ocean, it is possible for bicarbonate to convert back to CO2 and to re-enter the atmosphere. Currently, the ERW community has overlooked the ability of biological processes in rivers to convert bicarbonate back to CO2. Quantification and consideration of biological processes in rivers is needed to correctly estimate the amount of CO2 removed via ERW. We are using existing data, making measurements, and running models to estimate the extent to which biological processes affect the ability of weathered carbon to reach the ocean. Results will help ensure that EMW removes more CO2 from the atmosphere than it contributes to the atmosphere.

People Involved

Current - Becca Neumann . Mary Orrand

Funding

FY2024 National Science Foundation, Hydrologic Sciences & Geobiology and Low Temperature Geochemistry Program (MCA: Incorporating Stream Biogeochemistry into Carbon Assessment of Enhanced Rock Weathering: A Machine Learning and Dynamic River Network Modelling Approach)

FY2024 National Science Foundation, Environmental Engineering (CAS-Climate: Enhanced mineral weathering in agricultural fields: Quantifying carbon leakage in the river system )

Press & Outreach

Becca Neuamnn is serving as:

• Scientific advisor for Matii, a non-profit deploying enhanced rock weathering in Indian rice fields (2024 ­– present)

• Workgroup member for building and launching a v1.0 Community Quantification Standard for Enhanced Mineral Weathering as a Carbon Dioxide Removal Technology. Effort lead by Cascade Climate (2023 – present)

• Scientific advisor for CarbonPlan’s CDR Verification Framework for Enhanced Weathering and Biochar pathways (2022 – 2023)

Publications

Neumann, R. B., Kukla, T., Zhang, S., & Butman, D. E. (2025). Riverine photosynthesis influences the carbon sequestration potential of enhanced rock weathering. Frontiers in Climate, 7, 1582786. https://doi.org/10.3389/fclim.2025.1582786