An Attempt to Simulate Historic Front Variations of Nigardsbreen, Norway

Abstract

Nigardsbreen (Norway) is one of the very few highlatitude glaciers from which a long record of front positions is known (starting in the beginning of the 18th century). In this paper a dynamic glacier model is used to investigate the possible causes of the observed front variations. These variations are characterized by a rapid advance until 1748, and steady retreat, with some minor interruptions, after that time. Two time series are used as forcing functions that drive the dynamic model: (i) central England summer temperature, and (ii) a tree ring record from northern Sweden. It appears that forcing (i) does not work at all: an almost continuously growing glacier is predicted by the model. Forcing (ii) performs much better, although the maximum glacier extent comes too early. Interpretation of these results and some additional experiments suggest that the climatic warming after the little ice age has been much more pronounced in western Norway than in England, at least in summer. Winter precipitation in Norway probably decreased gradually during the last centuries.