Natural and societal consequences of climate-forced changes of Jostedalsbreen Ice Cap
RECENT MASS CHANGES ON JOSTEDALSBREEN ICE CAP
by Kamilla Hauknes Sjursen, March 4, 2025
Jostedalsbreen is highly sensitive to climate variability due to its maritime setting, with relatively warm summers and precipitation-rich winters. In a new JOSTICE publication in the journal Annals of Glaciology, we investigate recent mass changes on Jostedalsbreen and the main drivers of the spatiotemporal variability in these mass changes over the ice cap.
The climatic influence on a glacier is quantified through its surface mass balance, the difference between the accumulation of snow on the glacier surface in winter and the melting of snow and ice in the summer season. To understand how the mass of Jostedalsbreen has evolved in recent decades, we modelled the ice cap’s surface mass balance from 1960 to 2020 using high-resolution temperature and precipitation from the seNorge dataset. We used both detailed in-situ field measurements and observations based on satellite data to fine-tune the model, allowing us to accurately capture seasonal mass changes and spatial variations across the ice cap.
The front of Nigardsbreen in August 2011 (photo: Jacob Yde).
The model results reveal that Jostedalsbreen has lost a small amount of mass over the 60-year period, with an annual average of -0.07 meters water-equivalent per year. However, this average conceals significant spatial and temporal variability. During the 1990s the ice cap gained mass due to high winter accumulation, in line with the frontal advances that were recorded for several outlet glaciers around this time. Since the early 2000s, the ice cap has experienced significant mass losses, mainly due to increased summer melting driven by increased air temperatures. These results reflect possible changes in the drivers of mass changes on Jostedalsbreen. While its mass balance was largely dominated by variations in winter accumulation before the 2000s, increasingly negative summer mass balances have been the main control on mass balance in the 21st century.
The front of Nigardsbreen in August 2023 (photo: Jacob Yde).
Overall, the northern parts of Jostedalsbreen and low-lying glacier tongues showed the most negative balance values over the 60-year period, while the southern part showed slightly positive trends. These spatial variations can be attributed both to local topography as well as differences in precipitation patterns on the ice cap, revealing different sensitivities of regions of the ice cap to ongoing climate change.
The study provides important insights into Jostedalsbreen’s recent past and suggests that the combined influence of climatic variations and local topography will have significant impacts on future evolution of the ice cap. Moreover, it provides the basis for modelling the future changes on Jostedalsbreen and assessing the societal impact of these changes.