Climate of the past millennium inferred from varved proglacial lake sediments on northeast Baffin Island, Arctic Canada
This study uses 239+240Pu-dated varved sediments from Big Round Lake, a proglacial lake on northeast Baffin Island, Arctic Canada to generate a 1000-year-long, annual-resolution record of past climate. Varve thickness is positively correlated with July–August–September temperature measured at Clyde River, 70 km to the north of the lake (r = 0.46, p < 0.001). We therefore interpret the variability and trends in varve thickness to partially represent summer temperature. The coolest Little Ice Age temperatures occurred in this record from 1575 to 1760 AD and were approximately 1.5°C cooler than today (average from 1995 to 2005 AD) and 0.2°C cooler than the last millennium (average from 1000 to 2000 AD). Pre-twentieth-century warmth occurred during two intervals, 970–1150 AD and 1375–1575 AD; temperatures were approximately 1.2°C cooler than today, but 0.1°C warmer than the last millennium. The Big Round Lake varve-thickness record contains features similar to that reconstructed elsewhere in the eastern Canadian Arctic. This high-resolution quantitative record expands our understanding of arctic climate during the past millennium.
KeywordsVarves Late Holocene paleoclimate Arctic Lake sediments Air temperature proxy Paleolimnology
We are indebted to Jamesee Qillaq and the Inuit of Clyde River for their logistical support. Neal Michelutti was an indispensable field assistant. Yarrow Axford and Jason Szymanski provided valuable support and ideas in the early stages of this project. Thanks to Darrell Kaufman, Michael Ketterer, Candy Kramer, John Menzies, Emily Pratt, Caleb Schiff, and Al Werner for their help in sample analysis and preparation. Andrew Bukata provided valuable advice about statistics. We appreciate the licensing and logistical support provided by the Nunavut Research Institute and the National Science Foundation (VECO Polar Resources). This research is a contribution to the NSF-ARCSS 2 kyr Synthesis Project, grant ARC-0455024. The Geological Society of America partially supported this research in the form of a student research grant to EKT. EKT was supported by an NSF Graduate Research Fellowship. This manuscript was improved by insightful comments from Darrell Kaufman, Brian Menounos, and two other anonymous reviewers.
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