Length change measurements
Glacier length changes are a proxy for glacier area changes, and there by the result of mass balance changes. Long-term records indicate long-term volume changes. Length change records from a number of glaciers indicate the development of all the glaciers.
Outlet glaciers from ice caps along the coast advanced considerably during the 1990-ies. After year 2000 the same outlet glaciers have retreated up to 1000 meters. The more continental glaciers in Jotunheimen, along the Swedish border i Nordland, and in Lyngen and Finnmark have been retreating more or less continously since the 1930s. However, some glaciers in Jotunheimen, like Storjuvbrean and Bøverbrean, advanced slightly in the 1990s. The average 10 years recession of 29 glaciers is almot 200 meters.
Background and method
The first systematic lengt change measurements were initiated around 1900 at Jostedalsbreen, Folgefonna, Svartisen and in Jotunheimen by J. Rekstad at Bergen Museum (now Univerity of Bergen) and P.A. Øyen at University of Oslo. The monitoring was continued by K. Fægri and W. Werenskiold, and later by Olav Liestøl and Jon Ove Hagen at Norwegian Polar Institute. Since 1994, Hydrologiy Department at NVE has been responsible for the monitoring programme.
The distance from a fixed point (cairn, painted mark, reference bolt, or similar) to the glacier is measured in the same direction annually. The line should preferably represent a central flow line.
The length change observations are stored in NVE data base and are available under "Glacier data". The results are published in NVE report serie Glaciological investigations in Norway, and reported to World Glacier Monitoring Service (WGMS) and published in their 'Fluctuations of Glaciers’ (FoG).
Andreassen, L.M., H. Elvehøy, B. Kjøllmoen, and J.M.C. Belart, 2020. Glacier change in Norway since the 1960s - an overview of mass balance, area, length and surface elevation changes. Journal of Glaciology, 1-16. https://doi.org/10.1017/jog.2020.10.
Fægri, K. 1940: Forandringer ved norske breer 1937-39. Bergen Museums Årbok 1939-40. Naturvidenskapelig rekke. Nr 3.
Hoel, A. & Werenskiold, W.1962: Glaciers and snowfields in Norway. Norsk Polarinstitutt Skrifter Nr.114, 291 s.
Kjøllmoen, B. (ed.), 2019: Glaciological investigations in Norway in 2018. NVE Report No.46/2019.
Liestøl, O. 1964. Noen resultater av bremålinger i Norge i 1963. Norsk Polarinstitutt Årbok 1963., s. 185-192.
Rekstad, J., 1904: Fra Jostedalsbræen. Bergens Museums Aarbog 1904, No 1, 1-69.
Rekstad, J., 1910: Forandringer ved norske breer i aaret 1908-09. Bergens Museum Årbok 1910, 2-12.
Øyen, P.A., 1906: Klima- und Gletcherschwankungen in Norwegen. Zeitschrift fur Gletcherkunde, Eiszeitforschung und Geschichte. 1: 46-61.