HR: 0800h
AN: PP41A-0182    [Abstracts]
TI: Climate in North Iceland over the Past 2000 Years: Inferences from Midges and Other Lake- Sediment Proxies
AU: * Axford, Y
EM: yaxford@buffalo.edu
AF: Institute of Earth Sciences and Dept. of Geosciences, University of Iceland, Askja, Reykjavik, 101, Iceland
AU: * Axford, Y
EM: yaxford@buffalo.edu
AF: Dept. of Geology, University at Buffalo, 876 NSC, Buffalo, NY 14260, United States
AU: Geirsdottir, A
EM: age@hi.is
AF: Institute of Earth Sciences and Dept. of Geosciences, University of Iceland, Askja, Reykjavik, 101, Iceland
AU: Miller, G H
EM: gmiller@colorado.edu
AF: INSTAAR and Dept. of Geological Sciences, University of Colorado, UCB 450, Boulder, CO 80309, United States
AU: Langdon, P G
EM: P.G.Langdon@soton.ac.uk
AF: Dept. of Geography, University of Southampton, Highfield, Southampton, SO17 1BJ, United Kingdom
AB: Sediment cores from two lakes in north Iceland record environmental changes over the past 2000 years. Shifts in chironomid (non-biting midge) assemblages over the last two centuries at both lakes are coherent with instrumental temperatures recorded at Stykkisholmur in west Iceland. At Torfadalsvatn, which is small and shallow (Zmax=5 m), quantitative temperature inferences based upon an existing transfer function for Iceland compare well with Stykkisholmur temperatures. In contrast, at Stora Vidarvatn (Zmax=48 m) sample scores from detrended correspondence analysis are much better correlated with Stykkisholmur temperatures than are transfer-function based temperature inferences. Paleotemperature inferences from Stora Vidarvatn and Torfadalsvatn sediments bolster prior inferences from Icelandic historical records and other proxy-based climate reconstructions (e.g., Geirsdottir et al., this volume). Reconstructed temperatures during parts of the 10th and 11th centuries AD, the period of rapid Norse expansion in the region, were comparable to temperatures in warm decades of the 20th century. Declining biogenic silica concentrations, increasing C:N, and shifts in midge assemblages between the 13th and 19th centuries suggest declining summer temperatures, decreasing aquatic production, and increasing soil erosion. The most severe climatic conditions occurred in the 19th century, coincident with documented sea ice expansion around Iceland. Iceland sits at the present-day boundary (Polar Front) between Arctic and Atlantic surface currents in the North Atlantic, and Iceland's climate is tightly coupled to sea-surface conditions. The coherency and amplitude of cooling in the 13th through 19th centuries, along with the lag between the peak cold anomaly in north Iceland and presumed extremes in solar and volcanic forcings, may imply changes in surface ocean circulation that would have affected the larger northern North Atlantic region.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4914 Continental climate records
DE: 4942 Limnology (0458, 1845, 4239)
DE: 4950 Paleoecology
DE: 9315 Arctic region (0718, 4207)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting