A key unanswered question in global climate research is the extent to which the oceans absorb and redistribute anthropogenic CO2 (DeltaDICant). We apply an off-line ocean carbon cycle model, one that uses atmospheric CO2 concentrations and simplified ocean ventilation estimates. We estimate ocean ventilation by introducing the full age distributions of water masses obtained from a global ocean circulation model. The two model cases we use are known to respectively underestimate and overestimate observed ventilation rates, thereby providing upper and lower bounds on CO2 uptake. The error in determining DeltaDICant is reduced significantly by minimizing the number of tunable parameters. The development of the oceanic DeltaDICant inventory is resolved from the beginning of industrialization to the present time. According to the model, 177Gt anthropogenic carbon have been locked up in the oceans by 1999, corresponding to an annual uptake rate of 3.9GtC*a-1 during 1999. Uncertainties in our estimate oceanic CO2 uptake are discussed.