HR: 16:15h
AN: PP44A-02    [Abstracts]
TI: Late Holocene Temperature Reconstruction Inferred from a Varved Glacial Lake in the Central Brooks Range, Alaska, USA
AU: * Bird, B W
EM: bwb8@pitt.edu
AF: University of Pittsburgh, 4107 O'Hara Street 200 SRCC Building, Pittsburgh, PA 15260, United States
AU: Abbott, M B
EM: mabbott1@pit.edu
AF: University of Pittsburgh, 4107 O'Hara Street 200 SRCC Building, Pittsburgh, PA 15260, United States
AB: Climate models and recent observations suggest that the Arctic is warming more rabidly than any other region on Earth. However, few long-term temperature records exist that can place this recent warming trend in a larger context. Varved glacial lake sediments provide one such archive at annual resolution, provided that a relationship between varve thickness and near-surface temperature can be established. We present a paleotemperature record inferred from varve thicknesses measurements of cores collected from Blue Lake in the Central Brooks Range of Alaska, USA. Three distinct climatic periods are observed in the Blue Lake sediment record: 1) A period of thinner varves persists between ~1200-1900 AD, with a minimum thicknesses occurring between 1660 - 1900 AD, 2) after 1900 AD a warming trend is marked by increased varve thickness that continues to the present, 3) thicker varves prior to 1200 AD may indicate an interval of warmth equal to or greater than that of the 20th century. Our results suggest that 20th century warming in the Central Brooks Range is anomalous within the context of at least the last ~800 years, but periods prior to 1200 AD may have experienced warmth equal to or greater than the present.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1610 Atmosphere (0315, 0325)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting