The purpose of the US-Japan Joint Seminar is to examine similarities and differences in catchment science research and to synthesize work between the two countries. A workshop-style seminar is planned to facilitate structured exchange of ideas, foster discussion, and achieve consensus among bi-national participants. The theme of the last seminar was Forest Hydrology and Biogeochemistry. The integration of these areas has significantly developed in both the US and Japan and is evidenced by new programs in funding agencies (e.g., NSF’s Emerging Topics in Biogeochemical Cycles and Critical Zone Observatories), synthesis volumes, and collaborative research and exchange. In this seminar, we will extend the theme of linking hydrology and biogeochemistry with an emphasis on climatic and environmental change. The time is ripe for a multi-perspective synthesis of the effects that climatic forcing, natural disturbance, and forest management have on the timing, duration, and magnitude of hydrological and biogeochemical processes.