Chironomid-inferred summer air temperatures for northern Europe in the Late-glacial and Holocene
by
Stephen J. Brooks
Department of Entomology, The Natural History Museum, London, UK
Coauthors: H.J.B. Birks, (Botanical Institute, University of Bergen, Allégaten 41, N-5007 Bergen, Norway and Environmental Change Research Centre, University College London, London WC1H 0AP, UK)

Chironomids seem promising proxies to infer quantitatively past climate change using regression and calibration techniques because their broad-scale distribution and abundance is strongly influenced by air temperature. We have recently developed a chironomid-mean July air temperature transfer function, based on a modern calibration set of 157 Norwegian lakes, which has produced remarkable results when applied to late-glacial midge assemblages in Norway and Scotland when temperature fluctuations were of high amplitude. Results have been more equivocal from the Holocene. During the last 10,000 years air temperature change has been closer to the 1°C error margins of the inference model. Long- and short-term changes in other environmental variables during the Holocene, such as pH, water temperature and dissolved oxygen, may also have had a strong influence on midge assemblages and may compromise the reliability of temperature inferences. Other factors can also influence chironomid-inferred temperatures including the depth of water in which the core is taken, questions of taxonomic resolution and site selection (both for modern calibration sets and for palaeoclimate reconstructions). The poster discusses these problems and illustrates chironomid-inferred mean July air temperature reconstructions from four sites: Kråkenes (western Norway) and Whitrig Bog (Scotland) cover the late-glacial; Loch Nagar (Scotland) and Bjornfjell (northern Norway) are Holocene records and part of the CHILL 10,000 project.

Date received: March 15, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cagc-12.