Hidden subsurface suspended sediment export from Greenland's marine‐terminating glaciers

Abstract Runoff and calved ice volumes from the Greenland Ice Sheet are well constrained, but quantifying the associated suspended sediment flux remains challenging. Here we present near‐terminus observations from three glacierized fjords in southeast Greenland, combining full‐depth turbidity profiles and current velocity from summer 2024 to evaluate sediment export. We identify extensive subsurface sediment plumes from marine‐terminating glaciers which are undetectable using remote sensing approaches and underrepresented in fjord sediment‐core reconstructions. Sediment cores document an exponential increase in sediment accumulation rates from glacier‐distal to glacier‐proximal coring sites. Therefore, the scarcity of sediment cores collected in the immediate vicinity of glacier termini suggests that sediment export from marine‐terminating glaciers has likely been systematically underestimated. Our findings underscore the importance of direct observations for quantifying sediment transport in glacierized fjords and suggest the Greenland Ice Sheet contributes more sediment to ocean margins than previously assumed.