Chironomid-inferred late-glacial summer air temperatures from Lough Nadourcan, Co. Donegal, Ireland JENNY E. WATSON, 1 * STEPHEN J. BROOKS, 2 NICKI J. WHITEHOUSE, 1 PAULA J. REIMER, 1 H. JOHN B. BIRKS 3,4 and CHRIS TURNEY 5 1 School of Geography, Archaeology and Palaeoecology (GAP), Queen’s University Belfast, Belfast, UK 2 Department of Entomology, Natural History Museum, London, UK 3 Department of Biology and Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway 4 Environmental Change Research Centre, University College London, London, UK 5 School of Geography, University of Exeter, Exeter, UK Watson, J. E., Brooks, S. J., Whitehouse, N. J., Reimer, P. J., Birks, H. J. B. and Turney, C. 2010. Chironomid-inferred late-glacial summer air temperatures from Lough Nadourcan, Co. Donegal, Ireland. J. Quaternary Sci., Vol. 25 pp. 1200–1210. ISSN 0267-8179. Received 11 October 2009; Revised 5 February 2010; Accepted 9 February 2010 ABSTRACT: Western Ireland, located adjacent to the North Atlantic, and with a strongly oceanic climate, is potentially sensitive to rapid and extreme climate change. We present the first high- resolution chironomid-inferred mean July temperature reconstruction for Ireland, spanning the late- glacial and early Holocene (LGIT, 15–10 ka BP). The reconstruction suggests an initial rapid warming followed by a short cool phase early in the interstadial. During the interstadial there are oscillations in the inferred temperatures which may relate to Greenland Interstadial events GI-1a–e. The temperature decrease into the stadial occurs in two stages. This two-stage drop can also be seen in other late-glacial chironomid-inferred temperature records from the British Isles. A stepped rise in temperatures into the Holocene, consistent with present-day temperatures in Donegal, is inferred. The results show strong similarities with previously published LGIT chironomid-inferred temperature reconstructions, and with the NGRIP oxygen-isotope curve, which indicates that the oscillations observed in the NGRIP record are of hemispherical significance. The results also highlight the influence of the North Atlantic on the Irish climate throughout the LGIT. Copyright # 2010 John Wiley & Sons, Ltd. KEYWORDS: chironomid; late-glacial; Ireland; Lough Nadourcan; palaeoclimate. Introduction The late-glacial period was characterised by several rapid and extreme shifts in climate across the North Atlantic region. The magnitude of these shifts has been recognised from ice core and marine records (e.g. Koc ¸ Karpuz and Jansen, 1992; Alley et al., 1993; Walker et al., 2001a) and in terrestrial records from pollen, plant macrofossil and, particularly, coleopteran assemblages (e.g. Atkinson et al., 1987; Lowe et al., 1994; Birks et al., 2000). In recent years the development of chironomid-based transfer functions has enabled the magni- tude and rapidity of these temperature changes to be quantified at a high temporal resolution (Walker et al., 1991; Brooks and Birks, 2001). Chironomid analysis is ideally suited for generating high- resolution quantitative temperature reconstructions (Brooks, 2006; Walker and Cwynar, 2006). Chironomid (non-biting midge) larvae are abundant and show high species diversity in temperate and arctic lake deposits. Their short life cycles, ability to disperse rapidly over long distances and indepen- dence from pedogenic processes enable them to respond to changing climate and environment more rapidly than terrestrial vegetation (see, for example, Birks and Birks, 2008). Moreover, the major factor driving changing chironomid species assem- blages during the late-glacial has been shown to be climate (Walker and Mathewes, 1989; Walker et al., 1991, 1992). A number of chironomid-based transfer functions have been developed to reconstruct past summer temperatures quantitat- ively. Within Europe these include transfer functions developed from Norway (Brooks and Birks, 2001), Sweden (Larocque et al., 2001), Finland (Olander et al., 1999; Luoto, 2009) and Switzerland (Heiri et al., 2003). Earlier versions of the Norwegian transfer function based on fewer (109) lakes than the one used in this study (157 lakes) have been used to reconstruct late-glacial temperatures from Kra ˚ kenes in Norway (Brooks and Birks, 2000a) and Whitrig Bog in Scotland (Brooks and Birks, 2000b). Here, the results of a new investigation at Lough Nadourcan, Co. Donegal (Fig. 1) are presented. These include the first JOURNAL OF QUATERNARY SCIENCE (2010) 25(8) 1200–1210 Copyright ß 2010 John Wiley & Sons, Ltd. Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/jqs.1399 * Correspondence to: J. E. Watson, School of Geography, Archaeology and Palaeoecology (GAP), Queen’s University Belfast, Belfast BT7 1NN, UK. E-mail: j.watson@qub.ac.uk