Localized plumes drive front-wide ocean melting of a Greenlandic tidewater glacier

Abstract

Recent acceleration of Greenland's ocean-terminating glaciers has substantially amplified the ice sheet's contribution to global sea level. Increased oceanic melting of these tidewater glaciers is widely cited as the likely trigger, and is thought to be highest within vigorous plumes driven by freshwater drainage from beneath glaciers. Yet melting of the larger part of calving fronts outside of plumes remains largely unstudied. Here we combine ocean observations collected within 100 m of a tidewater glacier with a numerical model to show that unlike previously assumed, plumes drive an energetic fjord-wide circulation which enhances melting along the entire calving front. Compared to estimates of melting within plumes alone, this fjord-wide circulation effectively doubles the glacier-wide melt rate, and through shaping the calving front has a potential dynamic impact on calving. Our results suggest that melting driven by fjord-scale circulation should be considered in process-based projections of Greenland's sea level contribution.