Northampton Electronic Collection of Theses and Research

Merging chironomid training sets: implications for palaeoclimate reconstructions

Holmes, N., Langdon, P. G., Caseldine, C. J., Brooks, S. J. and Birks, H. J. B. (2011) Merging chironomid training sets: implications for palaeoclimate reconstructions. Quaternary Science Reviews. 30(19-20), pp. 2793-2804. 0277-3791.

Item Type: Article
Abstract: Icelandic and Norwegian chironomid calibration or training sets were merged to investigate whether a larger combined training set would be useful to apply to subfossil chironomid data from Iceland for periods such as the early Holocene, the Holocene Thermal Maximum and the Little Ice Age, when temperatures can be expected to be outside the current temperature range of the Icelandic training set. Following taxonomic harmonisation, the Icelandic and Norwegian data sets were compared before being merged to form a combined Norwegian-Icelandic training set. Analyses showed that it was biologically and statistically valid to merge the two data sets. The resulting combined inference model for mean July air temperature had improved performance statistics (r2jack = 0.87; RMSEPjack = 1.13) when compared to the best performing Icelandic model (r2jack = 0.61; RMSEPjack = 0.83), due to the longer environmental gradient covered (Icelandic 6–11 °C; combined 3.5–16 °C), and to the increased number of samples (Icelandic = 53 lakes; combined = 207 lakes) and taxa (Icelandic = 47 taxa; combined = 133 taxa) present within the combined training set. The inference models were applied to an early Holocene chironomid sequence from Vatnamýri, north Iceland, and a 450-year recent record from Myfluguvatn, north-west Iceland, to compare the reconstructions produced. The various inference models produced similar trends and patterns of temperature reconstruction, but the inference model based on the combined training set produced a larger range of reconstructed temperatures than the Icelandic model. It was found that different inference models produced more variation in the reconstruction than when different training sets were used. A comparison of the Myfluguvatn reconstructions with meteorological observations showed that the combined Norwegian–Icelandic inference model produced more reliable results than the Icelandic or Norwegian inference models alone.
Uncontrolled Keywords: chironomid, holocene, iceland, palaeoclimate, training set
Subjects: Q Science > QC Physics > QC851 Meteorology. Climatology > QC884 Palaeoclimatology
Creators: Holmes, Naomi, Langdon, Peter G, Caseldine, Chris J, Brooks, Stephen J and Birks, H John B
Funders or Sponsors: NERC studentship (NER/S/A/2002/10368A), EU QPALCLIMMarie Curie Training Site at the University of Bergen
Publisher: Elsevier
Faculties, Divisions and Institutes: University Faculties, Divisions and Research Centres - OLD > School of Science and Technology (2010-2016)
Faculties > Faculty of Arts, Science & Technology > Environmental Science
Date: 14 July 2011
Date Type: Publication
Page Range: pp. 2793-2804
Journal or Publication Title: Quaternary Science Reviews
Volume: 30
Number: 19-20
Language: English
ISSN: 0277-3791
Status: Published / Disseminated
Refereed: Yes

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