Glacier response in the European Alps to Heinrich Event 1 cooling: the Gschnitz stadial

Abstract

The Gschnitz stadial was a period of regionally extensive glacier advance in the European Alps that lies temporally between the breakdown of the Last Glacial Maximum piedmont lobes and the beginning of the Bølling warm interval. Moraines of the Gschnitz stadial are found in medium to small catchments, are steep-walled and blocky, and reflect a snowline lowering of 650-700 m in comparison to the Little Ice Age reference snowline. 10 Be surface exposure dating of boulders from the moraine at the type locality at Trins (Gschnitz valley, Tyrol, Austria) shows that it stabilised no later than 15 400 AE 1400 yr ago. The overall morphological situation and the long reaction time of the glacier suggest that the climatic downturn lasted about 500 AE 300 yr, indicating that the Gschnitz cold period began approximately 15 900 AE 1400 yr ago, if not somewhat earlier. This is consistent with published radiocarbon dates that imply that the stadial occurred sometime between 15 400 14 C yr BP (18 020-19 100 cal. yr) and 13 250 14 C yr BP (15 360-16 015 cal. yr). A palaeoclimatic interpretation of the Gschnitz glacier based on a simple glacier flow model and statistical glacier-climate models shows that precipitation was about one-third of modern-day precipitation and summer temperatures were about 10 K lower than today. In comparison, during the Younger Dryas, precipitation in this area was only about 10% less and T s (summer temperature) was only 3.5-4 K lower than modern values. Based on the age of the moraine and the cold and dry climate at that time, we suggest that the Gschnitz stadial was the response of Alpine glaciers to cooling of the North Atlantic Ocean associated with Heinrich Event 1.

The deglaciation of the mountains of Mexico and Central America

“…Similar glacier advances coeval to Heinrich-1 have been documented in the mid latitudes of the northern hemisphere (e.g. Ivy-Ochs et al, 2006). In contrast, the fact that deglaciation in Costa Rica and in the northern tropical Andes was in progress during Heinrich stadial 1, is probably an expression of the bipolar seesaw hypothesis postulated for Heinrich events, i.e.…”

Glacier variations in the European Alps at the end of the last glaciation

“…Sedimentological and paleobotanical studies of lake and bog sediments show that not only the main valleys but also the tributary valleys were ice-free at the beginning of the Bølling or just before. This is confirmed by radiocarbon dates that calibrate to between 15.9 and 14.3 ka cal BP from sites all across the Alps (Maisch, 1987;van Husen, 1997;Keller and Krayss, 2010;Ivy-Ochs et al, 2006;Kelly et al, 2006;Baroni et al, 2014;Heiri et al, 2014).…”

Timing of massive ‘Fleuve Manche’ discharges over the last 350kyr: insights into the European ice-sheet oscillations and the European drainage network from MIS 10 to 2

“…The decrease of the 'Fleuve Manche' activity was contemporaneous with the onset of the Canadian-derived IRD input (very low Ti/Ca ratio, i.e. dolomitic-rich sediment) in the Bay of Biscay (Grousset et al, 2000;Zaragosi et al, 2001;Ménot et al, 2006) and with a significant re-advance of the BIIS (McCabe et al, 2007;Bateman et al, 2008), FIS (Nygard et al, 2004;Knies et al, 2007) and central European glaciers (Buoncristiani and Campy, 2004;Ivy-Ochs et al, 2006) suggesting that subglacial material transfer from the European ice masses to the Bay of Biscay was markedly reduced during re-advance episodes. Cold and dry conditions over Europe, described as polar desert conditions at around 16 ka according to Kasse et al (2007), may also have favoured reduced fluvial transfer of sediment to the Bay of Biscay.…”