Atmosphere Ocean Science Colloquium
Holocene Ice-Sheet Readvance in Antarctica's Weddell Sea Sector
Speaker: Jonathan Kingslake, Columbia
Location: Warren Weaver Hall 1302
Date: Wednesday, March 25, 2026, 3:30 p.m.
Synopsis:
Sea-level rise is accelerating, predominantly due to the ice sheets shrinking. There is significant uncertainty related to how this will continue. Understanding how ice sheets have changed in the past can improve our predictions of future change by highlighting important processes and helping to test and tune ice-sheet models. This talk is about how West Antarctica changed during the Holocene. Until recently, it was assumed that the West Antarctic Ice Sheet shrank monotonically from an expanded state at the Last Glacial Maximum (LGM), to its current state, which it then maintained through most of the Holocene. In this talk I will describe a decade of work by myself and many others suggesting that after the LGM the ice sheet instead shrank to a size significantly smaller than today, then regrew to its current size in the Weddell and Ross sea sectors. In places, the grounding line may have reached more than 200 km inland of its current position.
I will discuss a wide range of evidence for retreat and readvance. This includes englacial structure mapped with ice-penetrating radar, englacial temperatures measured in boreholes, radiocarbon in subglacial water and sediments, and indicators of relative sea-level change.
The cause of Holoecene readvance in these sectors is debated. Potential causes include glacial isostatic adjustment and climate fluctuations. Which proves the best explanation has implications for our understanding of these sectors’ sensitivity to future climate-driven changes. I will argue that while climate fluctuations are the likely culprit in the Ross Sea Sector, the drivers of readvance in the Weddell Sea Sector are currently unclear. Finally, I will discuss future work that could improve our understanding of these sectors of the ice sheet and their climate sensitivity.