Plain Language Summary
The behavior of Antarctic glaciers will largely determine the pace and
magnitude of future sea level rise. But the projections made by ice
sheet models are uncertain, in part due to the uncertain response of
Antarctica to the future loss of its floating ice shelves. It has been
hypothesized that ice shelf breakup could trigger a self-sustaining
mechanism of ice loss whereby ice cliffs collapse under their own
weight. This idea is controversial because it has not been unambiguously
observed in modern glacier systems. We show that after the loss of its
ice shelf, Crane Glacier experienced a 2 year period of accelerating ice
loss, consistent with a geometric instability like the one proposed.
Models of ice cliff failure that assume glacier ice has pre-existing
weaknesses are more consistent with the behavior we observe at Crane
than models that assume pristine ice.