Southern Ocean Ecosystem Response to Last Glacial Maximum Boundary Conditions

Phytoplankton exert a significant control on the marine carbon cycle and can thus impact atmospheric CO2 concentration. Here we use new ecosystem model to analyze response of diatoms coccolithophores in Southern Ocean Last Glacial Maximum (LGM) climate conditions, changes aeolian iron (Fe) input Ocean. We find that LGM conditions without Fe lead large increase north winter sea ice edge South Atlantic (19%) Pacific (26%), 31% 9% within seasonal sea-ice zone Indian oceans, respectively, while decrease Ross Weddell Seas, (62%) south edge. Coccolithophores by 11% West near 45°S but are outcompeted zone, where they 21%. Overall, this results net primary productivity (NPP) 2.4% export production (EP). A series sensitivity experiments with different compared available paleo-proxy records. The best fit is obtained for simulation forced dust fluxes from Lambert et al. (2015), https://doi.org/10.1002/2015gl064250 reduced Antarctic Bottom Water formation Sea. 78% increases EP 4.4%, NPP remains 8.7% weaker preindustrial.