Exceptionally high biosphere productivity at the beginning of Marine Isotopic Stage 11

Significant changes in atmospheric CO₂ over glacial-interglacial cycles have mainly been attributed to the Southern Ocean through physical and biological processes. However, little is known about the contribution of global biosphere productivity, associated with important CO₂ fluxes. Here we present the first high resolution record of Δ¹⁷O of O₂ in the Antarctic EPICA Dome C ice core over Termination V and Marine Isotopic Stage (MIS) 11 and reconstruct the global oxygen biosphere productivity over the last 445 ka. Our data show that compared to the younger terminations, biosphere productivity at the end of Termination V is 10 to 30 % higher. Comparisons with local palaeo observations suggest that strong terrestrial productivity in a context of low eccentricity might explain this pattern. We propose that higher biosphere productivity could have maintained low atmospheric CO₂ at the beginning of MIS 11, thus highlighting its control on the global climate during Termination V.