Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate
the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale
glaciation of Antarctica (~34 Myr) by combining solid Earth and ocean dynamic modeling. A newly compiled
global early Oligocene topography is used to run a solid Earth model forced by a growing Antarctic ice sheet. A
regional Southern Ocean zonal isopycnal adiabatic ocean model is run under ice-free and fully glaciated (GIA)
conditions. We find that GIA-induced deformations of the sea bottom on the order of 50 m are large enough to
affect the pressure and density variations driving the ocean flow around Antarctica. Throughout the Southern
Ocean, frontal patterns are shifted several degrees, velocity changes are regionally more than 100%, and the
zonal transport decreases inmean and variability. The model analysis suggests that GIA induced ocean flow variations
alone could impact local nutrient variability, erosion and sedimentation rates, or ocean heat transport.
These effects may be large enough to require consideration when interpreting the results of Southern Ocean
sediment cores.