Carl Steefel is currently a Senior Scientist in the Energy Geosciences Division, Earth and Environmental Sciences Area at Berkeley Laboratory. He also serves as head of the Geochemistry Department. He has more than 30 years of experience in developing models for multicomponent reactive transport in porous media and applying them to topics in water-rock interaction, reactive contaminant transport, chemical weathering, isotopic exchange, and watershed modeling. Recent work has focused on modeling of geochemical transport and electrostatic effects in clay-rich rocks. He is the principal developer of the CrunchFlow software, which won an R&D100 Award in 2017 and was named an AGU Fellow in 2019.