Paleoclimatic implications based on equilibrium-line altitude depressions of reconstructed Younger Dryas and Holocene cirque glaciers in inner Nordfjord, western Norway

Abstract

Relative to a present cirque glacier in innner Nordfjord, western Norway, equilibrium-line altitude (ELA) depressions for reconstructed cirque glaciers formed during the Younger Dryas (11,000–10,000 yr B.P.), the Erdalen Event (9100±200 yr B.P.) and the Little Ice Age (mid-18th century) are calculated by the use of accumulation-area ratio (AAR), and compared to the corresponding values for plateau glaciers. The temperature-precipitation ELA (TP-ELA), as reflected by plateau glaciers, gives considerably larger ELA depressions than use of the temperature-precipitation-wind ELA (TPW-ELA) for cirque glaciers. ELA depressions during the Younger Dryas, Erdalen Event and the Little Ice Age thus strongly indicate that cirque glaciers are much more sensitive to changes in winter precipitation than plateau glaciers. The difference in ELA depressions of contemporaneous plateau and cirque glaciers during the Younger Dryas, Erdalen Event and the Little Ice Age suggests that winter precipitation was reduced to 59±7, 71±6 and 88±7% compared to present values. Taken into account the reduced winter precipitation, the corresponding mean ablation-season temperature depressions were probably 4.3±0.3, 3.0± 0.2 0.3 and 1.4± 0.3 0.2 ° C , respectively.