New Insights into the 8.2 ka Cold Event and Subsequent Climate Recovery in Central Europe Provided by a Precisely Dated Ostracod δ18O Record from Mondsee (Austria)

Wednesday, 16 December 2015
Poster Hall (Moscone South)
Stefan Lauterbach1, Nils Andersen2, Achim Brauer1, Helmut Erlenkeuser2, Dan L. Danielopol3, Tadeusz Namiotko4, Matthias Huels2, Soumaya Belmecheri5,6, Carla Nantke1, Hanno Meyer7, Bernhard Chapligin7 and Ulrich von Grafenstein6, (1)GFZ German Research Centre for Geosciences, Section 5.2 - Climate Dynamics and Landscape Evolution, Potsdam, Germany, (2)University of Kiel, Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Kiel, Germany, (3)University of Graz, Institute of Earth Sciences (Geology & Palaeontology), Graz, Austria, (4)University of Gdańsk, Department of Genetics, Laboratory of Limnozoology, Gdańsk, Poland, (5)University of Arizona, Tucson, AZ, United States, (6)Laboratoire des Sciences du Climat et de l’Environnement, UMR CEA-CNRS, Gif-sur-Yvette, France, (7)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Potsdam, Department of Periglacial Research, Potsdam, Germany
As evidenced by numerous palaeoclimate records worldwide, the Holocene warm period has been interrupted by several short, low-amplitude cold episodes. Among these, the so-called 8.2 ka cold event is the most prominent Holocene climate perturbation but despite extensive studies, knowledge about its synchrony in different areas and particularly about the dynamics of subsequent climate recovery is still limited. As this is of crucial importance for understanding the complex mechanisms that trigger rapid climate fluctuations and for testing the performance of climate models, new data on the 8.2 ka cold event are needed. Here we present a new sub-decadally resolved, precisely dated oxygen isotope (δ18O) record for the interval 7.7–8.7 ka BP obtained from benthic ostracods preserved in the varved lake sediments of Mondsee (Austria), providing new insights into climate development around the 8.2 ka cold event in Central Europe. The new high-resolution δ18O data set reveals the occurrence of a pronounced cold spell around 8.2 ka BP, whose amplitude (~1.0 ‰, equivalent to a 1.5–2.0 °C cooling), total duration (151 a) and absolute dating (8231–8080 a BP, i.e. calendar years before AD 1950) perfectly agree with results from other Northern Hemisphere palaeoclimate archives, e.g. the precisely dated Greenland ice cores. In addition, the Mondsee δ18O record also indicates a 75-year-long air temperature overshoot of ~0.7 °C directly after the 8.2 ka event (between 8080 and 8005 a BP), which is so far only poorly documented in the mid-latitudes. However, this observation is consistent with results from coupled climate models and high-latitude proxy records, thus likely reflecting a hemispheric-scale climate signal driven by enhanced resumption of the Atlantic meridional overturning circulation (AMOC), which apparently also caused synchronous migrations of atmospheric and oceanic front systems in the North Atlantic realm.