On the Estimation of Deep Atlantic Ventilation from Fossil Radiocarbon Records. Part II. (In)consistency with Modern Estimates

Abstract Measurements of radiocarbon concentration (Δ 14 C) in fossil biogenic carbonates have been interpreted as reecting a reduced ventilation the deep Atlantic during last ice age. Here we evaluate (in)consistency an updated compilation Δ C data for deglaciation with abyssal circulation modern Atlantic. A transport equation, which mean velocity field is estimate and turbulent flux divergence treated random fluctuation, fitted to deglacial records by using recursive weighted least-squares. This approach allows us interpret terms deviations from flow due regard uncertainties data, its boundary conditions. We find that majority fit residuals could be explained two distinct estimates error variance Thus, most, not all, appear consistent present-day rates. From 20 32% exceed magnitude published errors factor two. Residuals below 4000 m western North are all negative, suggesting values this region too low ventilation. Whilst water appeared different today at some locations, larger database better understanding (co)variances needed make reliable paleoceanographic inferences records.