HOLIVAR2006 Abstracts
Holocene climate reconstructions in Central Europe using botanical proxy data.
Norbert Kühl1 and Christian Schölzel2
1Institute of Paleontology, University of Bonn, Nussallee 8, 53115 Bonn, Germany
2Meteorological Institute, University of Bonn, Auf dem Hügel 20, 53121 Bonn, Germany
Contact: N. Kühl (kuehl@uni-bonn.de)
Climate reconstructions based on botanical data either use presence/absence data (Indicator Taxa Approaches) or pollen percentage data from pollen assemblages (Modern Analogue Techniques). During the last years, an Indicator Taxa Method was developed that is based on probability density functions for describing the plant-taxon relationship ("pdf-method", Kühl et al. 2002), using Bayesian statistics.
The method uses presence/absence data, hence the method can use climate sensitive taxa that have a low pollen representavity and can incorporate pollen as well as macrofossil data. It is robust to the lack of modern analogues, which is an advantage in highly anthropogenically influenced areas such as Europe. However, using presence/absence information means that climatic information recorded as change of pollen percentages cannot be discovered. It is therefore of interest to evaluate the performance of the method compared to other methods and other proxies. As of yet, temperatures of past interglacials have been reconstructed (Kühl and Litt 2003, Kühl and Litt in press), and here we present for the first time reconstructions with the pdf-method for Holocene January and July temperatures as well as annual precipitation.
One of the three sites with pollen data is located in Northern Germany, and two in the Eifel region. They have a high sample resolution and an absolute chronology based on varve counts. Some major events are visible in the reconstructions of all sites, differences occur in detail. The Early Holocene optimum is reconstructed for July temperature, which is consistent with reconstructions using other methods (e.g., Seppä and Birks 2001). A Mid-Holocene decrease in January temperature is reconstructed between approx. 4000 and 6000 yr BP, which is in accordance with e.g. reconstructions using a Bayesian reconstruction approach, but with chironomids as proxy data (Korhola et al. 2002), and with other evidence. More methodological work and comparisons are planned to further explore the potential of the pdf-method.
Korhola, A., Vasko, K., Toivonen, H.T.T., Olander, H., 2002. Holocene temperature changes in northern Fennoscandia reconstructed from chironomids using Bayesian modeling. Quaternary Science Reviews 21, 1841-1860.
Kühl, N., Gebhardt, C., Litt, T., Hense, A., 2002. Probability Density Functions as Botanical-Climatological Transfer Functions for Climate Reconstruction. Quaternary Research 58, 381-392.
Kühl, N., Litt, T., 2003. Quantitative time series reconstruction of Eemian temperature at three European sites using pollen data. Vegetation History and Archaeobotany 12, 205-214.
Kühl, N., Litt, T., in press. Quantitative time series reconstructions of Holsteinian and Eemian temperatures using botanical data. In: Sirocko, F., Litt, T., Claussen, M., Sanchez Goñi, M.F. (Eds.), The climate of past interglacials.
Seppä, H., Birks, H.J.B., 2001. July mean temperature and annual precipitation trends during the Holocene in the Fennoscandian tree-line area: pollen-based climate reconstructions. The Holocene 11, 527-539.
Norbert Kühl is Hochschulassistent (a position similar to assistant professor) at the Institute of Paleontology of the University of Bonn, Germany. His research interests include quaternary pollen analysis, vegetational history and quantitative climate reconstructions. He carries out pollen analysis of Holocene as well as older sediments. His climate reconstructions have been focussed on former interglacials, and recently he applied his methods to the Holocene. A particular interest is the comparison of interglacials as well as the comparison of reconstructed and modelled climate.