The waxing and waning of Alpine glaciers throughout the last 10,000 years
by Prof. Walter Kutschera (Vienna University / VERA)
at SMI - Boltzmanngasse 3, 1090 Wien ( 3-2-08 - Seminarraum )
by Prof. Walter Kutschera,
It is well known that the Holocene, i.e. the geological time period of the last 11,000 years following the end of the Ice Age, enjoyed relatively stable temperatures. But glaciers are sensitive to even small temperature and/or climate changes, and the globally observed retreat of Alpine glaciers and polar ice sheets since 1850 AD (the end of the so-called Little Ice Age) has been linked to the temperature rise caused by the ever increasing release of CO2 and other greenhouse gases by human activities. On the other hand, it is now evident that considerable glacial fluctuations occurred already at much earlier times when the human impact was negligible.
In a way, the interest in Alpine glaciers of the past started with the accidental discovery of the famous Iceman Ötzi in 1991, a naturally mummified body which was well preserved for 5200 years in the icy environment of a high mountain pass (3210 m a.s.l.) in the Ötztal Alps . Since then, several periods of forward and backward movements of glaciers in the European Alps and in the New Zealand Alps throughout the last 10,000 years have been established with the help of dendrochronology, radiocarbon dating, surface exposure dating of rocks with various cosmogenic radionuclides (10Be, 14C, 26Al, 36Cl), and geomorphological considerations . It is possible that small solar activity variations, enhanced by (hitherto largely unknown) feed-back processes on Earth, caused the observed glacial fluctuations in the past. These natural fluctuations constitute a “background”, which is now being modified in a complex way by human activities. It is hoped that research on the movement of Alpine glaciers before man’s influence may actually help to better assess the anthropogenic influence on climate change in our time.