Modeling Climate Conditions Required for Glacier Formation in Cirques of the Rassepautasjtjåkka Massif, Northern Sweden

Abstract

Timing of cirque formation and the climate necessary to initiate glaciation are fundamental to the understanding of the landscape of the northern Scandinavian mountains. Empty cirques in the Rassepautasjtjåkka massif are located near a glaciated area and thus appear near the glaciation limit. In order to investigate the climate conditions necessary for glacier formation in the cirques, we applied a spatially distributed temperature index melt model. After calibration under present climate conditions, the model was run with different combinations of increased initial winter snow cover and lowered summer air temperatures to assess the climate conditions needed for snow to survive summer and hence form a base for glaciation. Results indicate that a significant increase in precipitation or decrease in summer air temperature or a combination of both is necessary to initiate glaciation. Thus current climate conditions are far from favorable for glaciation. If summer temperature is decreased by 4°C or winter snow cover is more than doubled, only 10% of cirque areas remain snow covered, which is considered as a minimum condition for glacier formation. According to climate reconstructions such conditions have not occurred during the Holocene suggesting that the cirques have not been glaciated during this period. Consequently glaciation of the cirques must have occurred during other parts of the glacial cycles.