Evaluating the Retreat, Arrest, and Regrowth of Crane Glacier Against Marine Ice Cliff Process Models

Abstract

AbstractThe fastest projected rates of sea level rise appear in models which include “the marine ice cliff instability (MICI),” a hypothesized but mostly unobserved process defined by rapid fracture and wastage of terminal ice cliffs that outpaces viscous relaxation and ice‐shelf formation. Crane Glacier's response to the Larsen B Ice Shelf collapse has been invoked as evidence of MICI in the observational record. Using available remote sensing data, we analyze Crane's retreat, arrest, and regrowth over the last two decades. Much of Crane's terminus retreat occurred in floating, not grounded ice. Retreat accelerated by at least 54% during the 2 years following ice shelf collapse. This is inconsistent with contemporaneous regional forcing that promoted ice shelf growth during this period, but consistent with a geometrically controlled positive feedback. We infer a maximum possible cliff height of 111 m, which according to process models, could enable cliff calving assuming damaged ice.