[show abstract][hide abstract] ABSTRACT: A lacustrine sediment core from Fiddaun, western Ireland was studied to reconstruct summer temperature changes during the Weichselian Lateglacial. This site is located close to the Atlantic Ocean; and so is potentially sensitive to climatic changes associated with changes in ocean circulation. The record, comprising the end of the Weichselian Pleniglacial to the early Holocene, was analysed for fossil chironomids, lithology, and oxygen and carbon isotopes in the sedimentary carbonates. These proxies clearly show rapid warming at the onset of the Lateglacial Interstadial, relatively high summer temperatures during the Interstadial, pronounced cooling during the Younger Dryas, and subsequent warming at the transition to the Holocene. Chironomid-inferred mean July air temperatures for the Interstadial are ~12.5-14.5°C, ~7.5°C for the Younger Dryas, and ~15°C for the early Holocene. Furthermore, this research provides evidence for at least two cold events during the Interstadial. These more moderate temperature oscillations can be correlated to Greenland Interstadial events 1b and 1d, on the basis of the age-depth model for the Fiddaun sequence. Based on multiple proxies, the first cold oscillation (GI-1d) was the more severe of the two in Ireland.
[show abstract][hide abstract] ABSTRACT: The Weichselian Lateglacial (14.7-11.7 ka cal BP) is marked by rapid climatic oscillations, as can be seen in the Greenland oxygen isotope records. In addition to Greenland Stadial 1 (or Younger Dryas), two distinct cold phases, GI-1b and GI-1d, occurred during Greenland Interstadial 1 (Lowe et al., 2008). How did these changes affect climate and vegetation in Ireland? Here we present a high-resolution multi-proxy study from Ireland, in which both climatic and environmental changes are reconstructed for the Lateglacial period. The reconstruction is based on a combination of oxygen isotope (climate reconstruction, correlation to Greenland ice cores), chironomid (summer temperature reconstruction) and pollen (vegetation reconstruction) analyses. Results show that warming at the onset of the Interstadial led to the development of open juniper and birch shrubland. This was replaced by herb-rich grassland in the second half of the Interstadial. Subsequently, the Younger Dryas cooling led to an expansion of tundra vegetation. In more detail, the chironomid and oxygen isotope data provide the first unambiguous evidence for the occurrence of at least two short-lived cold episodes during the Interstadial in Ireland. The first of these cold events, correlated to Greenland Interstadial 1d, led to a brief decline in Juniperus and Betula. The second cold event, correlated to Greenland Interstadial 1b, led to a temporary expansion of Artemisia. Reference Lowe J.J. et al., 2008. Synchronisation of palaeoenvironmental events in the North Atlantic region during the Last Termination: a revised protocol recommended by the INTIMATE group. Quaternary Science Reviews 27, 6-17.