Temperature-induced marine export production during glacial period



[1] Proxy records indicate that export production was enhanced at the onset of the last glaciation. We examine how glacial cooling affects marine export production through temperature-dependent phytoplankton productivity and organic carbon remineralization using glacial climate simulation. Compared with the standard assumption of no temperature dependence as applied in existing paleoclimate models, including temperature-dependence enhances export production globally under glacial climate conditions. The near freezing temperatures of Antarctic seawater significantly reduce organic carbon remineralization. Less remineralization than production results in increasing carbon export to the deep ocean. Nutrients remaining near the surface at high latitudes are advected to lower latitudes via Antarctic Intermediate Water, enhancing primary production, and hence export, in temperate and tropical regions as well. Including temperature-dependence improves the model's agreement with the glacial proxy records of export production and stable carbon isotopes even under stably stratified conditions with a weakening of North Atlantic Deep Water.