Brief communication: The Glacier Loss Day as an indicator of a record-breaking negative glacier mass balance in 2022

Abstract

In the hydrological year 2021/2022, Alpine glaciers showed unprecedented mass loss. On Hintereisferner (Ötztal Alps, Austria), the glacier-wide mass balance was -3319kgm-2. Near-daily observations of the surface elevation changes from a permanent terrestrial laser scanning set-up allowed the determination of the day when the mass balance of Hintereisferner started to become negative. This Glacier Loss Day (GLD) was already reached on 23 June in 2022 and gave way to a long ice ablation period. In 2021/2022, this and the high cumulative positive degree days explain the record-breaking mass loss. By comparing the GLDs of 2019/2020-2021/2022, we found a gross yet expressive indicator of the glacier's imbalance with the persistently warming climate.