Zuckerman Postdoctoral Scholar, William Daniels and colleagues, present a new 16,000-year winter-spring temperature reconstruction derived from the unsaturation ratio of alkenones (U37K) in a continuous sedimentary sequence from Lake E5, northern Alaska.
Their reconstruction shows that winter-spring temperatures warmed rapidly during the deglaciation at 16 and 14 thousand years before present and continued to warm gradually throughout the middle and late Holocene (0.12–0.28 °C/thousand years) in concert with regional sea surface temperature and sea ice records. The results are consistent with climate model simulations and they attribute Holocene warming to rising winter-spring insolation, radiative forcing from rising greenhouse gas concentrations and regional feedbacks.
Their reconstructed cold season warming equaled or exceeded summer cooling according to a regional synthesis of temperature records, suggesting that seasonal biases in temperature reconstructions may account for proxy-model disagreements in Holocene temperature trends from Eastern Beringia.
Dr. Daniels current research involves analyzing multiple sedimentary proxies to reconstruct paleoclimate and paleoecology of St. Paul Island, a remote site in the Bering Sea that was a late-persisting home to Pleistocene megafauna such as mammoths. His research will explore the connections between ocean and atmosphere circulation during periods of rapid climate change, as well as links between climate and ecology.