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Deep-ocean carbonate ion concentrations ([C[O.sub.3.sup.2-]]) and carbon isotopic ratios ([delta][sup.13]C) place important constraints on past redistributions of carbon in the ocean-land-atmosphere system and hence provide dues to the causes of atmospheric C02 concentration changes. However, existing deep-sea [C[O.sub.3.sup.2-]] reconstructions conflict with one another, complicating paleoceanographic interpretations. Here, we present deep-sea [C[O.sub.3.sup.2-]] for five cores from the three major oceans quantified using benthic foraminiferal boron/calcium ratios since the last glacial period. Combined benthic [delta][sup.13]C and [C[O.sub.3.sup.2-]] results indicate that deep-sea-released C[O.sub.2] during the early deglacial period (17.5 to 14.5 thousand years ago) was preferentially stored in the atmosphere, whereas during the late deglacial period (14 to 10 thousand years ago), besides contributing to the contemporary atmospheric C[O.sub.2] rise, a substantial portion of C[O.sub.2] released from oceans was absorbed by the terrestrial biosphere. 10.1126/science.1193221

Over the past million years, Earth climate has experienced large-scale oscillations between glacial and interglacial conditions. Increasing evidence from ice cores and marine and terrestrial sediment cores shows that during [...]