ORIGINAL PAPER A comparison of three Eurasian chironomid–climate calibration datasets on a W–E continentality gradient and the implications for quantitative temperature reconstructions Stefan Engels • Angela E. Self • Tomi P. Luoto • Stephen J. Brooks • Karin F. Helmens Received: 27 November 2012 / Accepted: 24 February 2014 / Published online: 7 March 2014 Ó Springer Science+Business Media Dordrecht 2014 Abstract Multiple regional chironomid–climate calibration datasets are available to reconstruct quan- titatively July air temperatures from fossil chironomid assemblages. We examined the relationship between July air temperature and the 40 most common chironomid taxa in three independent Eurasian cali- bration (training) sets. The estimated temperature optimum of each chironomid taxon is systematically lower (by *1–2 °C) in a Norwegian calibration set compared to Finnish and Russian calibration sets. This result might partly be explained by the fact that the Norwegian calibration set extends further at the cold end of the temperature gradient. A difference in continentality between the Russian sites and the European sites might also contribute to this pattern. The number of taxa that show a statistically significant unimodal response to temperature is higher in the Norwegian calibration set (34 out of 40 taxa) compared to the modern Finnish (11 of 37 taxa; 3 common taxa absent) and the Russian calibration set (20 of 40 taxa), probably due to the longer temperature gradient incorporated in the Norwegian calibration set. We applied all three calibration sets to fossil chiron- omid assemblages from the high-latitude study site of Sokli (northeast Finland), a site with a unique series of lacustrine deposits covering (amongst others) the Holocene, part of early MIS 3 (at *53 ka) and MIS 5d–c (at *110–95 ka) and with independent proxy- records for comparison. In the early Holocene and during MIS 5c, the chironomid-based temperature inferences from all three inference models had similar values. Temperature reconstructions based on the Norwegian calibration set are 2–4 °C lower for the late Holocene, early MIS 3 and MIS 5d than the inferred temperatures based on the other calibration sets. Although the lakes included in the Finnish calibration Electronic supplementary material The online version of this article (doi:10.1007/s10933-014-9772-8) contains supple- mentary material, which is available to authorized users. S. Engels (&) Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Science Park 904, 1090 GE Amsterdam, The Netherlands e-mail: s.engels@uva.nl A. E. Self Á S. J. Brooks Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK e-mail: a.self@nhm.ac.uk S. J. Brooks e-mail: s.brooks@nhm.ac.uk T. P. Luoto Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland e-mail: tomi.luoto@helsinki.fi K. F. Helmens Department of Physical Geography and Quaternary Geology, Stockholm University, 10691 Stockholm, Sweden e-mail: karin.helmens@natgeo.su.se 123 J Paleolimnol (2014) 51:529–547 DOI 10.1007/s10933-014-9772-8