Jessica Gagliardi

Jessica analyzes Antarctic subglacial chemical precipitates using geochronological and geochemical tools to characterize past hydrologic activity of the Antarctic Ice Sheet. This record of past hydrologic activity is then used to investigate how the Antarctic Ice Sheet has responded to different parts of the climate system such as ocean temperature, and sea level in the past. These findings have implications for our understanding of how sensitive the Antarctic ice sheet is to climate change.

Marine and terrestrial archives of the Antarctic ice sheet provide windows into the ice sheet’s history, but they disagree as to when and how the ice sheet responded to the rapid global warming that ended the most recent ice age. Further constraints on the timing of the Antarctic ice sheet response to early deglacial warming are needed to better understand the deglaciation. Here we present geochronological dates from subglacial chemical precipitates, which can be used as a proxy for subglacial hydrologic activity, collected in the Ross Sea area of Antarctica. All calcite samples share the same age of ~16,000 years old, coinciding with a period of strong Southern Ocean warming. The calcite ages also coincide with cosmogenic exposure data that allow for contemporaneous ice lowering, as well as multiple other proxies that suggest a broader Antarctic ice response at this time, including records of ice rafted debris and detrital uranium in corals. We interpret this to mean that an early ice response caused a subglacial response, which is recorded in the precipitates.