The Ventilation of the North Atlantic Ocean During the Last Glacial Maximum - a Comparison Between Simulated and Observed Radiocarbon Ages

The distribution of radiocarbon during simulations of the Last Glacial Maximum with a coupled ocean-atmosphere-sea ice model is compared with sediment core measurements from the Equatorial Atlantic Ceara Rise, Blake Ridge, Caribbean Sea and South China Sea. During these simulations, we introduce a perturbation of North Atlantic freshwater fluxes leading to varying strengths of the Atlantic meridional overturning. The best fit with the observations is obtained for an overturning weakened by 30% - 40% compared with today. Further, we simulate the phenomenon of an 'age reversal' found in deep-sea corals, but we suggest that this indicates rather a sudden interruption of deep water formation instead of an increase in ventilation which was suggested earlier.