David Keller is a scientist at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany. His research interests include marine biogeochemistry, the climate system, and assessing proposed climate engineering methods. Although he has conducted experimental field work in the past in estuarine systems, he currently mostly uses Earth system models to understand interactions between biogeochemical cycles and the climate system. David Keller is one of the coordinators of the Carbon Dioxide Removal Model Intercomparison Project (CDR-MIP). He has a PhD from the University of Maryland in Marine, Estuarine, and Environmental Science with a specialization in biological oceanography.