Reconstruction of Low and Middle Latitude Export Productivity, 30,000 Years BP to Present: Implications for Global Carbon Reservoirs

Based on organic carbon accumulation rates, nine time slices of oceanic export paleoproductivity (Pnew) are presented which depict the variability of Pnew on a global scale through the last 30,000 years and document that the basic distribution patterns did not change through glacial and interglacial times. However, the glacial ocean shows an increased contrast of high- versus low-productivity zones. δ13C values of near-surface-dwelling planktonic foraminifera Globigerinoides ruber suggest that the same contrast applies to the glacial nutrient inventories of the ambient surface waters, with a significant glacial transfer of PO4 from low- to high-productivity zones. In this way, glacial Pnew increased by a global average of about 2–4 Gt Cyr−1 and led, via an enhanced CaCO3 dissolution and alkalinity in the deep ocean, to a significant extraction of CO2 from the surface water and the atmosphere