The goal of the project is to better understand the variability of the Southern Ocean carbon sink and to improve the ability to detect physical and biogeochemical responses to current and future environmental changes. Specifically, the aim is to (1) quantify the sensitivity of the Southern Ocean circulation to the surface climate over inter-annual to centennial timescales and, to (2) evaluate how circulation changes impact the natural and anthropogenic carbon fluxes, and to (3) determine the �??fingerprint�?� pattern of physical and biogeochemical properties for the detection of predicted climate change impacts. The background material is presented very clearly in terms of the circulation variability and the anthropogenic vs. natural CO2 source/sink and the role of eddies, winds, and stratification changes on interannual to centennial time scales. The hypothesis and the science questions are clearly presented and the model experiments with a forced OGCM coupled to two different ecosystem models and a high-resolution eddy-permitting run are compatible with the scientific questions posed. The role of oxygen and carbon isotopes as validation tools are also accounted for. A team member is someone who has worked on this very problem for her PhD, which will contribute to the success of the proposed work. This proposal addresses a problem that is well established already and using an ecosystem model that may have limited applicability in reality. The self-organizing model is obviously an interesting concept but has no carbon model yet and has yet to be tested in varying environmental forcing despite it’s impressive results in a climatological sense. However, the proposed use of the FGM should provide a useful check on the self-organizing model.