About 20 years of science on terrestrial Enhanced Weathering

Using crushed rock products as a soil amendment or for enhanced plant growth is an old method and literature on this topic goes back to the early 20^th century and before. However, the systematic conceptualization of terrestrial mineral reactions as a carbon capture strategy was prominently outlined in an article by Schuiling and Krijgsman (2006). Their work might be seen as a pivotal starting point for systematically discussing the method of Enhanced Weathering in the scientific literature, which was now 20 years ago. Early studies evaluated underlying principles and tried to assess the carbon dioxide removal (CDR) potential. As the research field of Enhanced Weathering became more mature, additional aspects and processes were brought into the discussion. Considering the nearly unlimited possible combinations of the application of ground rock/alkaline products to the terrestrial system – across different soil systems, located in different climates and including diverse ecosystems or agricultural systems - makes the understanding of the underlying processes and rates of matter transfer highly relevant. This includes, liberating cations from rock/alkaline material, “parking” cations in soil pools, assessing the influence of organic acids, carbonate formation, changes in soil organic carbon, transport of alkalinity or co-benefits with other CDR-methods. I will reflect on this journey, which began in the specialized domain of geology and geochemistry and has since evolved into a highly interdisciplinary research field at the intersection of agronomy, climate policy, and economics. While many aspects remain to be fully elucidated, an Enhanced Weathering CDR industry is emerging, with carbon credits already issued. Therefore, ongoing, collaborative research remains critical to refining our understanding of geochemical uncertainties and environmental co-benefits.