Negative mass balance at Austdalsbreen and Near Balance at Nigardsbreen in 2024/2025

by Hallgeir Elvehøy, December 4, 2025

As 2024/2025 gave near average winter and summer mass balances on Jostedalsbreen, the resulting annual balances were negative on Austdalsbreen and near balance on Nigardsbreen.

The winter balances at Austdalsbreen and Nigardsbreen were 97% and 102% of the 1991-2020 averages, and the summer balances were 100% and 95% of the 1991-2020 averages, respectively. The resulting mass balance for Austdalsbreen was close to the long-term average of –0.60 m w.e. per year. For Nigardsbreen, the annual mass balance was +0.1 marginally more positive than the long-term average of –0.05 m w.e. per year.

Since the start of the JOSTICE project in 2020, the cumulative annual balances for Austdalsbreen and Nigardsbreen have been –5.2 and +1.0 m w.e., respectively.

Austerdalsbreen on 26 August 2025. Note the tilted iceberg to the right (photo: Per Solnes/NVE).

The outlet glaciers from Jostedalsbreen are retreating. Austerdalsbreen retreated 300 meters as the central part of the terminus with the medial moraine calved off during the summer. Based on our glacier ice thickness measurements from 2021 and 2022, the lake is probably about 30 meters deep at the glacier terminus. If the glacier continuous to retreat the proglacial lake can become 2.5 km long and up to 50 meters deep.

The average terminus retreat for five measured outlet glaciers was –22 meters (not including Austerdalsbreen). The observed front variations varied between –11 meter for Stigaholtbreen in Jostedalen and –42 meters for Brenndalsbreen in Stryn. Since the start of JOSTICE, the six outlet glaciers have retreated between 71 (Fåbergstølsbreen) and 475 meters (Austerdalsbreen). Austerdalsbreen has retreated 909 meters since 2000.