Preprints
https://doi.org/10.5194/cp-2021-54
https://doi.org/10.5194/cp-2021-54

  25 May 2021

25 May 2021

Review status: this preprint is currently under review for the journal CP.

Early Holocene cold snaps and their expression in the moraine record of the Eastern European Alps

Sandra M. Braumann1,2, Joerg M. Schaefer2, Stephanie M. Neuhuber1, Christopher Lüthgens1, Alan J. Hidy3, and Markus Fiebig1 Sandra M. Braumann et al.
  • 1University of Natural Resources and Life Sciences (BOKU), Peter Jordan-Str. 82, 1190 Vienna, Austria
  • 2Lamont-Doherty Earth Observatory of Columbia University, Division of Geochemistry, Palisades, NY 10964, USA
  • 3Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA

Abstract. Glaciers preserve climate variations in their geological and geomorphological records, which makes them prime candidates for climate reconstructions. Investigating the glacier-climate system over the past millennia is particularly relevant because, first, the amplitude and frequency of natural climate variability during the Holocene provides the climatic context against which modern, human-induced climate change must be assessed. Second, the transition from the last glacial to the current interglacial promises important insights into the climate system during warming, which is of particular interest with respect to ongoing climate change.

Evidence of stable ice margin positions that record cooling during the past 12 ka are preserved in two glaciated valleys of the Silvretta Massif in the Eastern European Alps, the Jamtal (JAM) and the Laraintal (LAR). We mapped and dated moraines in these catchments including historical ridges using Beryllium-10 Surface Exposure Dating (10Be SED) techniques, and correlate resulting moraine formation intervals with climate proxy records to evaluate the spatial and temporal scale of these cold phases. The new geochronologies indicate two moraine formation intervals (MFI) during the Early Holocene (EH): 10.8 ± 0.7 ka (n = 9) and 11.2 ± 0.8 ka (n = 12). Boulder ages along historical moraines (n = 6) imply at least two glacier advances during the Little Ice Age (LIA; c. 1250–1850 CE), around 1300 CE and in the second half of the 18th century. An earlier advance to the same position may have occurred around 500 CE.

The Jamtal and Laraintal moraine chronologies provide evidence that millennial scale EH warming was superimposed by centennial scale cooling. The timing of EH moraine formation is contemporaneous with brief temperature drops identified in local and regional paleoproxy records, most prominently with the Preboreal Oscillation (PBO), and is consistent with moraine deposition in other catchments in the European Alps, and in the Arctic region. This consistency points to cooling beyond the local scale and therefore a regional or even hemispheric climate driver. Freshwater input sourced from the Laurentide Ice Sheet (LIS), which changed circulation patterns in the North Atlantic, is a plausible explanation for EH cooling and moraine formation in the Nordic region and in Europe.

Sandra M. Braumann et al.

Status: open (until 20 Jul 2021)

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Sandra M. Braumann et al.

Sandra M. Braumann et al.

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Short summary
Glacier reconstructions provide insights into past climatic conditions and elucidate processes and feedbacks that modulate the climate system both in the past and present. We investigate the transition from the last glacial to the current interglacial and generate Beryllium-10 moraine chronologies in glaciated catchments of the Eastern European Alps. We find that rapid warming was superimposed by centennial scale cold phases that appear to have influenced large parts of the Northern hemisphere.