¹⁰Be measurements in bedrock constrain erosion beneath the Greenland Ice Sheet margin

Glacial erosion is a key process driving landscape evolution, but it remains unclear what factors dictate the rate at which subglacial erosion occurs. Moreover, estimates of subglacial erosion that do not rely on sediment flux techniques are rare. Here, we present in situ ¹⁰Be measurements from bedrock surfaces in western Greenland with well-constrained ice-cover histories to quantify the erosion rate beneath the Greenland Ice Sheet margin during historical times. We calculate an abrasion rate of 0.72 ± 0.35 mm yr⁻¹ and a likely total basin-wide erosion rate (abrasion + quarrying) of ~1–1.8 mm yr⁻¹, which are at least 1 order of magnitude higher than typical subglacial erosion rates in other polar landscapes. A compilation of published ¹⁰Be data suggests that the southwestern Greenland Ice Sheet acts as a particularly effective erosional agent within the broader Baffin Bay-Greenland region over millennial to glacial-interglacial timescales, suggestive of a basal ice sheet thermal regime controlled by regional climate.