Validation of chironomid-inferred temperature reconstructions in Iceland : the potential for reconstructing quantitative changes in Holocene climate

N Holmes

doi:10.5194/gh-63-4-2008

Abstract

Abstract. Subfossil chironomids in short cores from two lakes in western Iceland were analysed and a chironomidmean July air temperature transfer function applied to produce chironomid-inferred temperature reconstructions for the recent past. These reconstructions were compared with local meteorological data in order to evaluate the technique in Iceland. The chironomidinferred temperature reconstructions showed similar patterns and magnitudes of change to those recorded in the instrumental data, but the chironomid temperature reconstructions slightly underpredicted the observed temperatures. This suggests that the chironomids are able to reconstruct sequence trends of temperature change although the accuracy of the actual figures produced needs to be addressed. Subfossil chironomids in Iceland can be used to reconstruct the relatively small magnitude temperature changes of the last few hundred years, and also the larger magnitude changes experienced earlier in the Holocene.

Highlights

MethodsIntroductionConcern over the extent to which anthropogenic activity has forced recent changes in climate and could contribute to future climatic change has been the focus of many recent studies (Intergovernmental Panel on Climate Change, IPCC, 2001, 2007)
The potential of subfossil chironomids to reconstruct past changes in temperature has been demonstrated by a number of Lateglacial studies undertaken in the northern hemisphere (e.g. Bedford et al 2004; Brooks & Birks 2000a, b; Porinchu et al 2003)
The comparison of the chironomid-inferred temperature (C-IT) reconstructions with the Stykkishólmur meteorological data suggests that the subfossil chironomids from Iceland do respond to, and are able to successfully reconstruct the relatively small magnitude variations in temperature that have occurred during the recent period, despite the observed temperature changes in the meteorological record being close to the error limits of the chironomid-mean July air temperature calibration model

Summary

Methods

IntroductionConcern over the extent to which anthropogenic activity has forced recent changes in climate and could contribute to future climatic change has been the focus of many recent studies (Intergovernmental Panel on Climate Change, IPCC, 2001, 2007). The study of biological proxy data has the potential to provide information on the possible ecological effects any future climatic changes may have on lake ecosystems and their biota The potential of subfossil chironomids to reconstruct past changes in temperature has been demonstrated by a number of Lateglacial studies undertaken in the northern hemisphere Caseldine et al (2003) produced the first quantitative palaeolimnological study from Iceland, using the Norwegian chironomid-mean July air temperature transfer function (Brooks & Birks 2001; unpub.) showing the potential of subfossil chironomids present in Icelandic lakes as a climate proxy. The recent development of a chironomid-inferred mean July air temperature calibration model for Iceland (Caseldine et al 2006; Langdon et al.) provided the opportunity to try to evaluate and validate the technique within Iceland.

Results

Discussion

Conclusion