Towering ice cliffs at the leading edges of some glaciers are a key unknown in projections of sea-level rise. Scientists still cannot say with confidence how these walls of ice will behave as the climate warms.
Satellite data now offers some clues. The observations suggest that the cliffs may not fail in a single, steady collapse, but rather in fits and starts — episodic bursts of breakup that could change how fast ice is lost.
The findings help narrow the range of possible behaviours, but they do not settle the question. Further observations and modelling will be needed to understand the mechanics of cliff collapse and its implications for the glaciers' future.