Glacial ocean carbon maximized by weak circulation and high nutrient utilization

MUGLIA, JUAN; SKINNER, LUKE; SCHMITTNER, ANDREAS

Portland

Conferencia; 2018 Ocean Sciences Meeting; 2018

Atmospheric CO2 concentrations were lower during glacial periods than during interglacials. This difference has been attributed to higher glacial ocean carbon storage, due to changes in circulation and/or organic matter export to the deep ocean. However, three-dimensional, quantitative reconstructions of the glacial ocean constrained by multiple proxies from glacial sediments remain lacking. Here we use a physical-biogeochemical model to explore effects of different overturning circulation configurations and Southern Ocean iron fertilization on the distributions of carbon (d13C and D14C) and nitrogen (d15N) isotopes and ocean carbon storage. We find that models that are consistent with sediment reconstructions are characterized by a weak, shallow Atlantic overturning and enhanced Southern Ocean nutrient utilization. This combination maximizes ocean carbon storage, and represents an important advance in the quantitative, three-dimensional reconstruction and understanding of the glacial ocean and its carbon cycle.