Abstract
Increased rates of meltwater discharge from the Antarctic ice sheets since the 1950s have freshened the ocean around Antarctica and altered the salinity, density, and volume of Antarctic Bottom Water, the cold salty water mass that supplies the lower limb of the global overturning circulation. The largest changes have been observed in the Ross Sea, Antarctica's largest drainage basin. Here, we present a 6,400-year delta (super 18) O (sub diatom) record of glacial discharge from two marine sediment cores located in the southwestern Ross Sea. Our record shows enhanced glacial discharge between 6 and 5.5 ka, a period when terrestrial records of glacial lowering and marine sediment cores indicate that the Antarctic ice sheets underwent a rapid phase of mid-Holocene retreat in the Ross Embayment, and since the mid-20th century. Our study establishes that modern freshening in the Ross Sea is outside the range of natural variability during the last 5,500 years and consistent with a period of sustained ice sheet mass loss.