His main research interests center around land surface processes and climate change with a particular emphasis on research into Arctic terrestrial climate system feedbacks, including the impact of permafrost degradation on carbon, water, and energy cycles, and into land-use change impacts on climate. He is a co-lead of the Community Terrestrial Systems Model (CTSM), an effort to unify land modeling across NCAR and the broader research community. He is co-chair of the Land Use Model Intercomparison Project (LUMIP) for CMIP6 and co-chair of the Permafrost Carbon Network Model Integration group.