A modeling assessment of the interplay between aeolian iron fluxes and iron-binding ligands in controlling carbon dioxide fluctuations during Antarctic warm events

We add a prognostic biogeochemical model to the Bern3D ocean circulation model to test the impact of increased aeolian iron fluxes in various regions of the ocean on long time scales. Atmospheric CO2 is most sensitive when modern dust flux is increased 100-fold in the Southern Ocean for 1000 years, resulting in a reduction of 10 ppmv. Seeding the Indian Ocean and South Pacific results in increased export production and CO2 drawdown in the Southern Ocean due to interbasinal transport of iron. The non-sea-salt calcium record from Dome C, Antarctica, is used to scale aeolian iron deposition in the Southern Ocean in transient simulations over four Antarctic warm events of the last glacial period. Our results suggest changes in dust flux to the Southern Ocean played a limited role in modulating CO2 variations. The impact of iron fluxes on CO2 is dependent on parameter values chosen for the iron-binding ligand.