Thomas R Chudley, Ian M Howat, Michalea D King, Emma MacKie

The extent of surface crevassing on the Greenland Ice Sheet is a large source of uncertainty in processes controlling mass loss, including iceberg calving, ice rheology, and water routing. However, no work to date has comprehensively mapped the location of surface crevasses or examined their evolution through time. Here, we use high-resolution digital elevation models to map the 3-dimensional volume of crevasse fields across the Greenland Ice Sheet in 2016 and 2021. Whilst the change in the total volume of crevasses between these two years was within measurement error (+4.3 ± 5.9%), large and significant increases occurred at accelerating marine-terminating sectors of the ice sheet (up to +25.3 ± 10.1%). These increases were offset only by a reduction in crevasse volume in the central west sector (-14.2 ± 3.2%), particularly at Sermeq Kujalleq (Jakobshavn Isbræ), which underwent a temporary slowdown over the study period. Changes in crevasse volume correlate strongly with antecedent discharge changes, indicating that Greenland’s acceleration is affecting significant increases in crevassing on a timescale of less than five years. This rapid response provides a mechanism for mass-loss-promoting feedbacks on sub-decadal timescales, including increased calving, faster flow, and accelerated water transfer to the bed.