ausblenden:
Schlagwörter:
early late glacial; Alpine lake; multi-proxy data; summer water temperatures; climate; North Atlantic ice-rafted debris
DDC:
550 - Earth sciences
Zusammenfassung:
High-resolution multi-proxy analyses of a sediment core section from Lake Jeserzersee (Saissersee) in the piedmont lobe of the Wu¨rmian Drau glacier (Carinthia, Austria) reveal pronounced climatic oscillations during the early late glacial (ca. 18.5– 16.0k cal a BP). Diatom-inferred epilimnetic summer water temperatures show a close correspondence with temperature reconstructions from the adjacent Lake La¨ngsee record and, on a hemispheric scale, with fluctuations of ice-rafted debris in the North Atlantic. This suggests that North Atlantic climate triggered summer climate variability in the Alps during the early late glacial. The expansion of pine (mainly dwarf pine) between ca. 18.5 and 18.1k cal a BP indicates warming during the so-called ‘La¨ngsee oscillation’. The subsequent stepwise climate deterioration between ca. 18.1 and 17.6k cal a BP culminated in a tripartite cold period between ca. 17.6 and 16.9k cal a BP with diatom-inferred summer water temperatures 8.5–10 8C below modern values and a shift from wet to dry conditions. This period probably coincides with a major Alpine glacier advance termed the Gschnitz stadial. A warmer interval between ca. 16.9 and 16.4k cal a BP separates this cold phase from a second, shorter and less pronounced cold phase between ca. 16.4 and 16.0k cal a BP, which is thought to correlate with the Clavadel/Senders glacier advance in the Alps. The following temperature increase, coupled with wet (probably snow-rich) conditions, caused the expansion of birch during the transition period to the late glacial interstadial.
