North Atlantic storm track changes during the Last Glacial Maximum recorded by Alpine speleothems

Abstract

The European Alps are an effective barrier for meridional moisture transport and are thus uniquely placed to record shifts in the North Atlantic storm track pattern associated with the waxing and waning of Late-Pleistocene Northern Hemisphere ice sheets. The lack of well-dated terrestrial proxy records spanning this time period, however, renders the reconstruction of past atmospheric patterns difficult. Here we present a precisely dated, continuous terrestrial record of meteoric precipitation in Europe between 30 and 14.7 ka. In contrast to present-day conditions, our speleothem data provide strong evidence for preferential advection of moisture from the South across the Alps supporting a southward shift of the storm track during the local Last Glacial Maximum (that is, 26.5–23.5 ka). Moreover, our age control indicates that this circulation pattern preceded the Northern Hemisphere precession maximum by ~3 ka, suggesting that obliquity may have played a considerable role in the Alpine ice aggradation.

Late Quaternary climate and environmental reconstruction based on leaf wax analyses in the loess sequence of Möhlin, Switzerland

“…To the best of our knowledge, there are no independent continuous records of δ 2 H precip in Europe during the last glacial. Luetscher et al (2015) presented a δ 18 O record from a northern Alpine speleothem, but it overlaps only slightly with ours and shows very little variation from 30 to 15 ka (∼ 1 ‰ δ 18 O, which is equivalent to ∼ 8 ‰ δ 2 H). The only long continuous isotope records spanning the last 40 to 60 kyr currently come from an LPS in Crvenka, Serbia (R. , which shows not much more than 10 ‰ variability, and from marine cores offshore Portugal (Abreu et al, 2003) and in the Mediterranean Sea (Frigola et al, 2008).…”

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

“…Simulation s5, which has the highest cutoff value for the maximum accumulation rate (Eq. (10)), is meant to represent the other extreme: a wetter climate in the south that may have occurred as a result of moisture transport from south of the Alps that yielded significant accumulation in the high Alpine peaks (Luetscher et al, 2015) but that remained relatively cold and dry in the north near the glacier terminus. Other parameters (basal topography, glaciological parameters) 25 are identical for all simulations.…”

“…Two recent speleothems from a cave near Bern, Switzerland, also display these oscillations (Luetscher et al, 2015). These century to millennia timescale oscillations, called Dansgaard-Oscheger (DO) events, lasted through the Marine Isotope Stage 3 (MIS3, 60-30 ka BP) until the LGM (Railsback et al, 2015).…”

“…The same is true for accumulation which requires knowing patterns of rainfall and temperature. Since LGM 20 climate is known to have behaved rather differently from today owing to the southward displacement of the atmospheric polar front in the North Atlantic (Florineth, 1998;Hofer et al, 2012;Luetscher et al, 2015), it is questionable whether the added complexity of a PDD model results in a more accurate representation of LGM mass balance distribution. glacier (Haeberli and Penz, 1985) or with present-day Greenland values (Machguth et al, 2016) measured in regions where temperatures and precipitation are similar to estimated LGM conditions in northern Switzerland.…”

“…That period lasted around 2000 years in Greenland and in the Alps (see Luetscher et al, 2015, for the Bernese Alps). Probably as a result of the climate variability during the LGM period, the Rhine glacier left two closely-spaced terminal moraines in the Rhine lobe (e.g., Keller and Krayss, 2005a;Ivy-Ochs, 2015;Beckenbach et al, 2014).…”