Catastrophic ice-shelf break-up by an ice-shelf-fragment-capsize mechanism

Abstract

Two disintegration events leading to the loss of Larsen A and B ice shelves, Antarctic Peninsula, in 1995 and 2002, respectively, proceeded with extreme rapidity (order of several days) and reduced an extensive, seemingly integrated ice shelf to ajumble of small fragments. These events strongly correlate with warming regional climate and accumulation of surface meltwater, supporting a hypothesis that meltwater-induced propagation of pre-existing surface crevasses may have initiated ice-shelf fragmentation.We address here an additional, subsequent mechanism that may sustain and accelerate the ice-shelf break-up once it begins. The proposed mechanism involves the coherent capsize of narrow (less than thickness) ice-shelf fragments by rolling 90° in a direction toward, or away from, the ice front. Fragment capsize liberates gravitational potential energy, forces open ice-shelf rifts and contributes to further fragmentation of the surrounding ice shelf.