HOLIVAR2006 Abstracts
Subarctic aeolian deposits - a terrestrial response to Holocene climate variability.
Mia M. Kotilainen1 and Aarno T. Kotilainen2
1Department of Geology, P.O. Box 64, FIN-00014, University of Helsinki, Finland
2Geological Survey of Finland, P.O. Box 96, FIN-02151, Espoo, Finland
Contact: Mia Kotilainen (mia.kotilainen@helsinki.fi)
Global climate change is affecting the arctic region, its marine and terrestrial environment, extremely intensively (ACIA, 2005). In order to provide insight on future changes in these fragile environments information from proxy data e.g. marine and terrestrial records of the past could be used. One of the terrestrial records, not so often used, is aeolian deposits, dunes. Aeolian activity is indicative of climate change, especially in the arctic and subarctic regions (e.g. Koster 1988). The interaction between climate and aeolian activity is sensitive even to small changes in precipitation (Stetler and Gaylord 1996). In the present work we demonstrate how the terrestrial subarctic aeolian environment responds to climate change. We have studied two dune fields from Finnish Lapland to reveal subarctic aeolian history during the Holocene and thus provide insight on future changes in wind stress in these fragile regions. A total of 75 dune sections were studied and 54 conventional radiocarbon dates and 4 AMS dates of buried charcoal horizons were used for reconstructing the detailed aeolian reactivation chronology (Kotilainen 2004). The results suggest that six reactivation phases occurred during the Holocene and most of them can be connected with other climate proxies (e.g. drift ice in the North Atlantic). During the warmer climate phases (e.g. the Medieval Warm Period) the dune fields have been more stable, and during the colder phases (e.g. 8.2 kyr event) the dune fields have been more active.
These aeolian reactivation records provide information on land-ocean-atmospheric interactions during the Holocene. The stability during warm and moist conditions suggests that during the future global warming the stability of subarctic dune fields could be enhanced, which is good news for their preservation. The global warming causes severe problems in the high latitudes (ACIA 2005) but at same time the forecast for the aeolian landscapes becomes better. However, extra care should be taken in future land-use management of this fragile subarctic aeolian environment.
ACIA Scientific Report, 2005. 952 pp.
Koster, E.A.,1988. Ancient and modern cold climate aeolian sand deposition: a review. Journal of Quaternary Science, Vol. 3, pp. 69- 83.
Kotilainen, M.M., 2004. Dune stratigraphy as an indicator of Holocene climatic change and human impact in northern Lapland, Finland. Annales Academiae Scientiarum Fennicae, Geologica-Geographica 166, 154 pp.
Stetler, L.D. and Gaylord, D.R., 1996. Evaluating eolian-climatic interactions using a regional climate model from Hanford, Washington (USA). Geomorphology 17, 99-113.