A 2012–2021 high‐resolution glacier mass balance estimate for Icelandic ice caps based on ArcticDEM and ICESat‐2

Abstract

Ice caps are important water resources for Iceland and are threatened by climate change. Despite their importance and vulnerability, the geodetic glacier mass balance estimate for the recent decade lacks a high‐resolution result. To address this gap, we first co‐registered the 2012–2021 ArcticDEM (v4) strips with ICESat‐2 points acquired over off‐ice areas and evaluated the accuracy of the co‐registered DEMs. We then applied a per‐pixel weighted liner regression to the multi‐temporal ArcticDEM strips and generated a high‐resolution (2 m) glacier surface elevation change rate for six major Icelandic ice caps. Based on these estimates we calculated the geodetic mass balance. Additionally, we estimated the seasonal relative surface elevation changes using ICESat‐2 ATL06 data for the 2019 to 2021 period. The results showed the co‐registered ArcticDEM strips exhibit good accuracy, with a standard deviation of 1.15 m across the Icelandic ice cap regions. Between 2012 and 2021, Icelandic ice caps experienced a state of mass loss, with a surface elevation change rate of −0.57 ± 0.21 m/a, corresponding to a mass loss of −0.51 ± 0.02 m w.e/a. Spatial variability in glacier surface elevation changes among different Icelandic ice caps ranges −0.19 m/a to −0.75 m/a. The Langjökull ice cap exhibited the most severe glacier mass loss at −0.68 ± 0.006 m w.e/a. Furthermore, our observations indicate a change in seasonal trends occurred across all six ice caps from 2019 to 2021. Specifically, the glacier surface thickening decreased during the accumulation period, while the thinning rate increased during the ablation period. These findings highlight that ArcticDEM v4 strips provide new insights into the mass balance of Icelandic glaciers and will aid in making future water management decisions. Moreover, the high‐resolution surface elevation topography and change rates provided in this study may contribute to an improved understanding of the influence of glacier dynamics on glacier change.