EEPS Colloquium: Kiya Riverman

 A close look at the Thwaites Glacier grounding line: tidal flexure, subglacial seawater intrusions, and implications for ice-sheet stability

Glaciers have an Achilles heel: at the location where ice goes afloat on the ocean, small changes in the force balance can have an outsized effect on overall ice sheet stability. In particular, models have shown that if thin films of seawater are able to penetrate beneath otherwise grounded ice, glacier retreat is dramatically accelerated.

Here, I will present a suite of geophysical and oceanographic observations collected across the Thwaites Glacier, West Antarctica, that illuminate how processes at the grounding line control preset-day retreat. Multiple lines of evidence show seawater intrusions well inland of the grounding line, and we’ll discuss how these observations help explain why this part of Thwaites is retreating rapidly despite limited ocean-forced melt. To better understand how water gets beneath the glacier, I’ll show results from an elastic beam bending model that suggests that tidal pumping may be the cause. We’ll conclude by thinking about the role that physical models in the lab may play in better parameterizing subglacial seawater pumping processes for large-scale ice sheet models trying to predict future sea level rise from West Antarctica.

EEPS Colloquia are made possible by the William C. Ferguson Fund