An abrupt increase in the atmospheric 14 C content at the beginning of the Younger Dryas, about 13,000 years ago, has been related to a slow-down of the global oceanic circulation. This has been well simulated by box models, but the amplitude and timing of such a 14 C change could not be represented with dynamical models. We have forced a climate model of intermediate complexity with a meltwater discharge to test three model parameters that have the potential to strongly influence the simulated 14 C change and may help us to reconcile the model results with reconstructions. We find that a decrease of the tropical wind speed accompanying a slow-down of the oceanic circulation largely amplifies the circulation-induced 14 C change and brings it closer to the reconstructions. Second, we find that vertical mixing in a dynamical ocean model leads to a substantial damping in the 14 C response of simple models. Third, we demonstrate that neglecting radiocarbon 'reservoir age' variations during abrupt climate change may lead to a substantial overestimate of atmospheric 14 C fluctuations reconstructed from paleoceanographic archives.