Revisiting the mass balance of Bennett Island glaciation, East Siberian Sea

Bennett Island is located between the East Siberian Sea and the Arctic Ocean and is part of the De Long archipelago, which is the easternmost location in the high Arctic where terrestrial glaciation exists. It has an area of 155 km2, of which 36 percent is occupied by four ice caps. Here, we report unpublished direct measurements obtained in 1988–1989, when the variation in the winter (Bw) and annual mass balance (Ba) between individual glaciers ranged between 0.14 to 0.21 m w.e. and −0.05 to −0.33 m w.e. respectively. We also computed recent geodetic mass balance (2012–2022) of the ice caps using ArcticDEM data, which was found to be −5.33 ± 0.39 m w.e. Based on these measurements, we recalibrated a previously published regression model to reconstruct the Ba of the Toll Ice Cap, the largest ice body on the island. From 1960 to 2023, the cumulative mass balance of this ice cap was estimated to be −14.0 m w.e. which is much less negative than previously suggested. However, from 1991 to 2020, its mass loss doubled relative to 1961 to 1990, exhibiting a negative trend of −0.13 m w.e. decade−1 (p < .01). The last positive Ba likely occurred in 2001; since then, it has been consistently negative.