CARBOOCEAN IP aims at an accurate assessment of the marine carbon sources and sinks. Target is to reduce the present uncertainties in the quantification of net annual air-sea CO2 fluxes by a factor of 2 for the world ocean and by a factor of 4 for the Atlantic Ocean. The IP will deliver description, process-oriented understanding and prediction of the marine carbon sources and sinks with special emphasis on the Atlantic and Southern Oceans on a time scale -200 to 200 years from now. Expected breakthroughs by CARBOOCEAN IP will be firm answers to the following as yet unresolved questions:- How large are the Atlantic and Southern Ocean CO2 sinks precisely, i.e. how efficient is the downward transport of carbon in the deep-water production areas of the world ocean?- What do European rivers and shelf seas contribute to the large scale CO2 sources and sinks pattern of the North Atlantic Ocean in relation to uptake within Western Europe ?- What are the key biogeochemical feedbacks that can affect ocean carbon uptake and how do they operate ?- What is the quantitative global and regional impact of such feedbacks when forced by climatic change in the next 200 years? CARBOOCEAN IP will answer these questions through basic research in a strategic combination of extensive large-scale observations, process studies and advanced computer models focusing on all quantitatively important aspects. The project is based on three elements – observations, process studies, and integrative modelling – equivalent to description, understanding and prediction.