Late-Quaternary Climate Change Within the Beringian Buckle: Multidisciplinary Results From St. Michael Island

Zagoskin Lake is a 19 m deep maar beyond the limits of late Cenozoic glaciation that contains a 30,000 14C yr B.P. record of climate change. We quantitatively reconstructed the summer thermal regime using midge, diatom, and pollen data. Preliminary inferred mean July air temperatures based on the diatom and midge data show similar trends with LGM temperatures surprisingly similar to modern ones. In addition, both reach maximum values from about 11,000 to 9500 14C yr B.P. coincident with a peak of poplar pollen - a tree that does not occur on the island today. In contrast, the pollen-based reconstructions indicate a cold LGM relative to modern temperatures, a small peak in temperatures coincident with the poplar pollen peak, and then sustained high levels for most of the Holocene. Potential problems and how these differing records may be reconciled will be discussed.