Risk of Marine Ice Cliff Collapse Depends on Upstream Ice Thickness, Flow Rates and Sea Ice Debris

Science, June 18

The Thwaites Glacier of West Antarctica, draining an area the size of France is one of the most vulnerable glaciers to marine ice cliff collapse because it rests nearly entirely on deep seabed. As upstream regions of the glacier rapidly increase in thickness, the edge of the glacier can collapse under its own weight, thus accelerating ice loss and global sea-level rise. The disintegration or weakening of the floating ice shelf currently buttressing the Thwaites Glacier will expose enough of the glacier’s grounding line – the underwater region where it hits the ground – to initiate large-scale ice cliff retreat. This modeling study of ice dynamics found that, even if vulnerable locations like Thwaites start to collapse, small resistive forces from sea ice and calved debris may slow down collapse and related sea-level rise. At the same time, the study found that at certain flow rates, especially differing rates across the glacier under conditions of warming, cliffs may collapse more rapidly.

https://science.sciencemag.org/content/372/6548/1342