NOAA/WDS Paleoclimatology - LGM ocean model data exploring the role of ocean circulation and iron fertilization in the sequestration of atmospheric CO2

The role of glacial ocean circulation and iron fertilization in the sequestration of atmospheric CO2 are not well understood. Here we use a physical-biogeochemical model constrained by carbon and nitrogen isotopes to explore the effects of Atlantic Meridional Overturning Circulation (AMOC) and Southern Ocean iron fertilization on the distributions of these isotopes and ocean carbon storage. We find that a surprisingly weak (6-9 Sv) and shallow AMOC maximizes carbon storage and best reproduces the glacial sediment data. Increasing the atmospheric soluble iron flux in the Southern Ocean intensifies export production, carbon storage, and improves agreement with reconstructions. Our best fitting model suggests that a weak, shallow AMOC and enhanced iron fertilization conspired to enhance carbon storage in the glacial ocean.