The Southern Ocean is central to the climate’s response to increasing levels of atmospheric greenhouse gases as it ventilates a large fraction of the global ocean volume. Global coupled climate models and earth system models, however, vary widely in their simulations of the Southern Ocean and its role in, and response to, the ongoing anthropogenic forcing. The Southern Ocean Carbon and Climate Observations and Modeling project (SOCCOM) is an observational and modeling research program focused on the role of the Southern Ocean in the anthropogenic carbon budget, ocean biogeochemistry, and climate change. SOCCOM has deployed over 125 BGC-Argo floats equipped with pH, oxygen, nitrate and bio-optical sensors throughout the Southern Ocean waters south of 30°S. The data from the BGC-floats are used to constrain high-resolution coupled atmosphere-ocean model simulations that are designed to both increase our understanding of Southern Ocean processes and to reduce the uncertainty of projections of the future trajectory of the Earth’s carbon, climate and biogeochemistry.