2002 ARCSS All-Hands Workshop

Holocene Climate from Arctic Lake Sediment, Yukon Territory, Canada

Lesleigh Anderson¹, Mark B. Abbott², Bruce P. Finney³, Mary E. Edwards^4
1Department of Geosciences, University of Massachusetts Amherst, Morrill Science Center, Amherst, MA, 01003, USA, Phone (413) 545-2286, Fax (413) 545-1200, land@geo.umass.edu
²Department of Geology and Planetary Science, University of Pittsburgh, 321 Engineering Hall, Pittsburgh, PA, 15260, USA, Phone (412) 624-1408, Fax (412) 624-3914, mabbott1@pitt.edu
³Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA, Phone (907) 474-7724, Fax (907) 474-7204, finney@ims.uaf.edu
⁴Institue of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA, mary.edwards@svt.ntnu.no

High frequency climate variability in the northwest Arctic is a mystery relative to our understanding of the region's climate on millennial time-scales. This hinders our ability to evaluate recent and predicted warming within a context of natural variability. This research seeks evidence for sub-millennial scale climate change and its spatial pattern in Canada's interior Yukon Territory, over the last ~10,000 years. High-resolution sedimentological and geochemical data from three widely spaced, but similar, closed-basin lakes are used to estimate the regional climate history during the Holocene. The three study sites are located between 63° and 60°N in the semi-arid Yukon Plateau (<400 mm annual precipitation); Marcella Lake (60.074° N, 133.808° W), Seven Mile Lake (62.179° N, 136.376° W) and Jackfish Lake (63.020° N, 136.469° W). Each of the three study sites is a small (<3 km²), hydrologically closed, depressed kettle basin. Sediments are organic and carbonate rich and AMS radiocarbon ages indicate that they are complete Holocene sequences. The lakes are basic with high calcium concentrations, and bio-induced carbonate precipitation was evident. First, evidence that sediment-calcite oxygen isotope ratios are a proxy for aridity has been collected from a region-wide study of modern water and calcite. Second, sediment-core isotope data from three lakes are evaluated within the context of lake-level reconstructions and other climatic and limnologic proxy data. Lastly, the climate proxy data from a regional series of different lakes are compared. Results from this research have broad implications for understanding oxygen isotopes in lakes, natural climate variability, and climate forcing mechanisms for the northwest Arctic.

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