Controls on the altitude of Scandinavian cirques: What do they tell us about palaeoclimate?

Cirques are glacially eroded, bowl-shaped depressions, characterised by steep headwalls and flat or overdeepened floors. Given their association with past glaciers, cirques are sometimes used as proxies for palaeoclimate. However, cirques are shaped over multiple glacial cycles, and their usefulness as palaeoclimate indicators therefore remains open to question. In this paper, we map 3984 glacier-free cirques across the Scandinavian Peninsula and analyse variations in cirque floor altitude (CFA). We explore the relationships between CFAs and cirque aspect, latitude, longitude, and distance to the coast. We test the validity of using CFAs as indicators of palaeoclimate through comparison with the equilibrium-line altitudes (ELAs) of 513 modern cirque glaciers. Results indicate that both CFAs and modern cirque-glacier ELAs decrease with latitude and vary with aspect, being generally lowest on east-facing slopes. However, the clearest and strongest trend in both CFAs and modern cirque glacier ELAs is an increase in elevation with distance from the modern coast (i.e., distance 'inland'). This likely indicates that similar climatic gradients, particularly an inland reduction in precipitation, acted to regulate former sites of glacier initiation (reflected by CFAs) and modern glacier ELAs. This would imply that CFAs are a useful proxy for palaeoclimate. However, we note that both CFAs and modern ELAs reflect the general topography of this region (with increasing elevations moving inland), and the glacial history of the area (indirectly linked to palaeoclimate) may have played a role in regulating where cirques have formed. For these reasons, we suggest that palaeoclimatic interpretations derived from CFAs should be treated with caution.

Automated summary

By mapping and analyzing the distribution and altitude variations of cirques in the Scandinavian Peninsula, the study suggests that cirque floor altitude (CFA) may serve as a proxy for paleoclimate. The results reveal close relationships between CFA and factors such as latitude, aspect, and distance to the coastline, indicating potential links to ancient climate conditions.