Benthic foraminiferal Li/Ca decreases down a Norwegian Sea holothermal depth transect, suggesting that the saturation state of seawater with respect to calcium carbonate influences foraminiferal Li/Ca. Benthic foraminiferal Li/Ca increases by 17% across the glaciation event in the early Oligocene, which likely reflects the increase in seawater saturation state evidenced by the concomitant deepening of the calcite compensation depth. Following the establishment of the Antarctic ice sheet, benthic foraminiferal Li/Ca bears a remarkable resemblance to the estimated oxygen isotopic composition of seawater, suggesting that during this time seawater saturation was largely controlled by glacioeustatically driven changes in shallow-water carbonate accumulation rates.