Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice shelf geometry

Abstract

Abstract. Despite the potentially detrimental impact of large-scale\ncalving events on the geometry and ice flow of the Antarctic Ice Sheet,\nlittle is known about the processes that drive rift formation prior to\ncalving, or what controls the timing of these events. The Brunt Ice Shelf in\nEast Antarctica presents a rare natural laboratory to study these processes,\nfollowing the recent formation of two rifts, each now exceeding 50\u2009km in\nlength. Here we use 2 decades of in situ and remote sensing observations,\ntogether with numerical modelling, to reveal how slow changes in ice shelf\ngeometry over time caused build-up of mechanical tension far upstream of the\nice front, and culminated in rift formation and a significant speed-up of\nthe ice shelf. These internal feedbacks, whereby ice shelves generate the\nvery conditions that lead to their own (partial) disintegration, are\ncurrently missing from ice flow models, which severely limits their ability\nto accurately predict future sea level rise.