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 750 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 at least 1930.
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 continues by K. Fægri and W. Werenskiold, and later by Olav Liestøl 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.
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