14-10 Holocene Lake Sediments from Across Greenland (Kalaallit Nunaat) Reveal Key Impacts of Warmer Arctic Summers

Session: Lake Sedimentary Records of Past Climate and Environment

Presenting Author:

Yarrow Axford

Authors:

Axford, Yarrow¹, Chipman, Melissa², Larocca, Laura³, McFarlin, Jamie⁴, Nash, Bailey⁵, Osburn, Magdalena R.⁶, Puleo, Peter⁷, Schellinger, Grace⁸, Tuccillo, Mia⁹

(1) Northwestern University, Evanston, , (2) College of William and Mary, Williamsburg, , (3) Arizona State University, Tempe, , (4) University of Wyoming, Laramie, , (5) Northwestern University, Evanston, , (6) Northwestern University, Evanston, , (7) University of Wisconsin - Whitewater, Whitewater, , (8) Northwestern University, Evanston, , (9) Northwestern University, Evanston, ,

Abstract:

Geologic records of past warm periods reveal how the Earth system responds to climate warming, and thereby provide clues about how future warming might unfold. Quaternary scientists have long shown that Greenland, like many parts of the Arctic, experienced temperatures notably warmer than pre-Industrial in the early to middle Holocene due to elevated summer insolation.

Here we summarize three key lessons from our investigations of clastic stratigraphy, paleoecology, molecular biomarkers, and oxygen and hydrogen stable isotope geochemistry in Holocene lake sediments from around Greenland’s margins. We highlight that (1) insolation-driven Holocene Thermal Maximum warming varied in timing and magnitude around Greenland, but in coastal regions generally brought summers up to 2-5 ºC warmer than pre-Industrial. (2) That magnitude of summer warming drove widespread loss of the glaciers and ice caps that define many of Greenland’s coastal regions today, a pattern pieced together by numerous research groups using lake sediments as unique recorders of continuous glacial histories. And (3) warming also drove important changes in lakes themselves, including threshold shifts in summer thermal stratification and changes in lake level and bottom-water oxygenation. Our third point implies that future Arctic warming could drive widespread intensification of Arctic lake stratification and anoxia, an under-appreciated impact of anthropogenic climate change. Such future changes in lakes could have consequences for carbon cycling across broad swaths of the Arctic, and for the quality of water resources utilized by Arctic communities.

We thank the people and government of Greenland (Kalaallit Nunaat) for permitting us to conduct this research on their land, and for their partnership that made this research possible.

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