The Younger Dryas climatic conditions in the Za Mnichem Valley (Polish High Tatra Mountains) based on exposure-age dating and glacier-climate modelling

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Abstract

Cosmogenic 36Cl was measured in bedrock and moraine boulders in the Za Mnichem Valley (High Tatra Mountains). The post-LGM deglaciation of the study area occurred about 15.9 ka ago. The northernmost part of the valley slopes was ice-free around 15 ka ago. The terminal moraine on the valley threshold was finally stabilized 12.5 ka ago during the Younger Dryas cold event (Greenland Stadial 1). At that time, the Za Mnichem glacier was 1.3 km long and had an area of 0.57 km2. The AAR equilibrium line of the glacier was located at 1990 m a.s.l., which corresponds to an ELA depression of ∼500 m compared to today. The mean summer temperature was colder by 4°–4.5°C than the present-day temperature. The mean annual temperature was colder by 6°C than today. Such conditions suggest a decrease of the annual precipitation by ∼15–25% compared with the present-day annual average. These data indicate a probable uniform temperature change across central and western Europe, with the precipitation being the most significant factor affecting the mass balance of mountain glaciers. The spatial distribution of balance data suggests increasing continentality towards the east during the Younger Dryas.

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