Remote Sensing of Damage Feedbacks and Ice Shelf Instability in Antarctica

Abstract

The timing and magnitude of global sea level rise remains difficult to predict, driven for a large part by the potential instability of ice shelves in Antarctica. Ice shelves, the floating extension of the Antarctic ice sheet, govern the mass loss of the ice sheet by providing resistance (buttressing) to the grounded ice — thereby modulating the ice flow to the ocean. The short-term collapse or long-term weakening of ice shelves can result in drastic increases of ice discharge and Antarctic mass loss. Understanding the processes that affect the weakening, retreat, and instability of ice shelves is therefore essential in order to improve sea level rise predictions.

Damaged areas on ice shelves, consisting of fractures, crevasses and/or rifts, are first indicators of its weakening. As ice shelves weaken, they can provide less buttressing to the ice sheet, causing accelerated ice flow, heightened internal stress, and increased strain rates. This creates a feedback loop, further promoting damage development and ice mass loss through increased discharge. Moreover, the propagation of crevasses or rifts through the ice shelf eventually leads to calving of (often large) ice bergs. Observable damage is therefore an important precursor to this mode of mass loss. Damage has been considered key for the collapse of the Larsen B ice shelf and the retreat of Pine Island Glacier and Thwaites Glacier. Despite its significance for future ice shelf stability, damage processes remain one of the least understood in marine ice sheet dynamics. This dissertation therefore aims to improve our understanding of damage impacts on ice shelf weakening and retreat from an observational perspective.ined...