Hanns Kerschner
Research Interests
- Glaciers and climate during the Alpine Lateglacial (Termination 1) / Gletscher und Klima im Alpinen Spätglazial
- Alpine climatology, synoptic climatology / Alpine Klimatologie, synoptische Klimatologie
Current research focuses mainly on the glacier and climate history of the "Alpine Lateglacial" and early Holocene. The "Alpine Lateglacial" covers the period between the onset of the final recession of glaciers from the foreland of the Alps until the end of the Younger Dryas cold phase around 11.500 years ago. During that period, glaciers readvanced several times to successively smaller end positions, leaving prominent systems of end moraines and associated ice marginal deposits.
Our aim is to establish a chronology of these events, to reconstruct glacier topographies and to provide a palaeoclimatic interpretation. In close cooperation with the Institute of Particle Physisc (ETH Zürich) (Dr. Susan Ivy-Ochs), surface exposure dating with terrestrial cosmogenic radionuclides (10Be, 26Al, 36Cl) provides new insights into the chronology of the events. Presently we focus on the time slice before the onset of the Bølling-Interstadial (Greenland Stadial 2a / Oldest Dryas / Heinrich-1 ice rafting event) and on the transition period from the Younger Dryas to the early Holocene.
An overview of the present knowledge in tabular form (from Ivy-Ochs et al., 2006) can be found here. A state-of-the-art report on surface exposure dating of moraines in the Alps can be found here. Caution: file size is quite large.
Glaciers are potentially reliable sources of palaeoclimatic information. Above all, they may provide quantitative information on past precipitation régimes, which is difficult to obtain from other proxies. For older periods of the Alpine Lateglacial, e.g. the period of the Heinrich-1 ice rafting event, glaciers are the only reasonable proxy for quantitative palaeoclimatic information in wide areas of the Alps. Analytical and empirical glacier-climate models and simple glacier flow models are used for the palaeoclimatic interpretation of the field work.
From a climatic and glaciological point of view, we can distinguish two different phases of the "Lateglacial", which are separated by the Bølling-Allerød-Interstadial. During the first phase, which corresponds roughly to Greenland Stadials 2b and 2a, glaciers were of the subarctic type with low shear stress along the glacier tongue, flat mass balance gradients and probably cold accumulation areas. The lowering of the ELA was still quite substantial. For example, during the Gschnitz Stadial around 16 ka, the ELA at the type locality was about 700 m lower than during the Little ice Age (LIA). Correspondingly, climate was rather dry and cold and bore more resemblance to a full glacial climate. This is not surprising, because the large ice-sheets still had quite a substantial extent during that period. During the Younger Dryas, glaciers were already much smaller and most of them were of the present-day alpine type. The ELA was roughly 200 to 400 m lower than during the LIA maximum, depending on the location of the individual glacier relative to the northern fringe of the Alps. Accordingly, climate was characterized by lower summer temperatures than today, and in the central valleys of the Alps it was also somewhat drier. Younger Dryas precipitation showed a higher regional contrast than today. However, in total Younger Dryas climate in the Alps already resembled Holocene conditions more than those of the pre-Bølling climate. More information can be found here.
Research is embedded into the research networks "Climate and Cryosphere" and "Global Change and Regional Sustainability" at the University of Innsbruck. Financial support was provided by the Austrian Research Foundation (Fonds zur Förderung der wissenschaftlichen Forschung) under project grants P12600-GEO and P15108-N06 and by the Marie-Curie-programme of the EU. Much work is done without special financial support: We live in our field area.
Our informal working group:
- Susan Ivy-Ochs, Institut für Teilchenphysik / Particle Physics ETHZ
- Christian Schlüchter, Geologisches Institut der Universitaet Bern
- Max Maisch, Geographisches Institut der Universitaet Zuerich
- Juergen Reitner, Geologische Bundesanstalt Wien / Geological Survey of Austria
- Phillipe Schoeneich, Institut de Géographie Alpine, Grenoble
- Rudolf Sailer, Institut fuer Geographie, Innsbruck
- Ralph Boehlert, Geographisches Institut der Universitaet Zuerich
Recent (and older) papers, some of them as PDFs for downloading, can be found in the "publications" folder.
A Powerpoint presentation can be downloaded here. Please keep in mind that it is not quotable.
November 19, 2008