24-22 Lake Sediment Reconstruction of Long-Term Changes in an Outlet Glacier of the Northern Margin of the Greenland Ice Sheet.

Session: Lake Sedimentary Records of Past Climate and Environment (Posters)

Poster Booth No.: 50

Presenting Author:

Hadley Blodgett

Authors:

Blodgett, Hadley¹, Balascio, Nicholas², D’Andrea, William³, Lapointe, Francois⁴, Perren, Bianca⁵, Bakke, Jostein⁶, Bradley, Raymond⁷

(1) Department of Earth & Climate Sciences, Bates College, Lewiston, , (2) Department of Earth & Climate Sciences, Bates College, Lewiston, , (3) Lamont-Doherty Earth Observatory, Columbia University, Palisades, , (4) School of Earth and Sustainability, University of Massachusetts, Amherst, , (5) British Antarctic Survey, Natural Environmental Research Council, Cambridge, , (6) Department of Earth Science and the Bjerknes Centre for Climate Research, University of Bergen, Bergen, , (7) School of Earth and Sustainability, University of Massachusetts, Amherst, ,

Abstract:

High-latitude environments are sensitive to climate change, with recent decades of warming strongly affecting glaciers and ice caps. Warming has caused the retreat of the Greenland Ice Sheet (GrIS) and adjacent mountain glaciers, particularly in high-latitude areas over the past two decades. However, short-term observations are insufficient to assess how these regions have responded to past natural climate variability. This study examines a proglacial lake sediment core from Lake Nukarleq (82.015388°N, 36.702127°W), providing the first high-resolution Holocene record from this lake. The core is used to reconstruct outlet glacier changes along the northern margin of the GrIS and the Storm Ice Cap in Inutoqqat Nunaat (Peary Land), northern Greenland. We analyzed a 2.45 m sediment core using sedimentological and geochemical methods, including grain size, density, organic matter, and X-ray fluorescence. A radiocarbon-based age model indicates that the record spans the last c. 7,000 cal yr BP. The sediments are mostly finely laminated, except for two distinct turbidite deposits, and comprise three major sedimentological units. From c. 7,000 to 1,500 cal yr BP, sedimentation consisted of fine laminations of organic-rich, low-density sediment. At c. 1,500 cal yr BP, organic content decreased, sediment density increased, and Ca variability became more pronounced, reflecting a substantial increase in glacially derived sediment and cooler environmental conditions. These conditions persisted until the last c. 50 years, when an abrupt shift to thick laminations and dense, fine-grained sediment demonstrated a warmer environment and extended ice-free seasons. These sedimentological changes, recorded at Lake Nukarleq’s climatically sensitive location, provide long-term context for Holocene glacier variability and reveal that recent ice retreat exceeds the range of variability observed through the Holocene. This record provides a basis for reconstructing ice extent and assessing the impacts of the Holocene Thermal Maximum, Neoglaciation, and recent warming on this High Arctic environment.

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