Middle to late Holocene chronology of the western margin of the Greenland Ice Sheet: A comparison with Holocene temperature and precipitation records

• Published in: Arctic, antarctic, and alpine research Vol. 50; no. 1; p. 1
• Main Authors: Levy, Laura B., Kelly, Meredith A., Applegate, Patrick A., Howley, Jennifer A., Virginia, Ross A.
• Format: Journal Article
• Language: English
• Published: Boulder Taylor & Francis 01.01.2018; Taylor & Francis, Ltd; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: 10be dating; Be dating; Bedrock; Beryllium 10; Boulders; Chronology; Climate change; Fjords; Fluctuations; Future climates; Greenland; Greenland ice sheet; Holocene; Ice; Ice sheets; Moraines; Paleoclimate; Precipitation; Sea level; Summer temperatures; Greenland
• ISSN: 1523-0430; 1938-4246
• DOI: 10.1080/15230430.2017.1414477

The response of the Greenland Ice Sheet to future climate change is relatively unconstrained. Determining the extents and rates of ice-margin fluctuations during the Holocene provides a longer-term perspective on ice-sheet changes and offers an analogue of how the ice-sheet may respond to future changes. Here, we present sixteen new 10 Be ages of boulders on moraines, boulders perched on bedrock, and bedrock surfaces that mark the timing of ice-margin fluctuations during the Holocene in the Kangerlussuaq region of southern west Greenland. We show that the Keglen moraines date to 8.0 ± 0.3 ka (n = 6) and that the average ice-margin retreat rate slowed from about 49 to 13 m yr −1 after about 8.0 ka, likely in response to the ice margin retreating onto land at the head of the fjord Kangerlussuaq at this time. The average retreat rate further slowed to less than 1 m yr −1 between 6.8 ka and 4.2 cal kyr BP, a time when nearby paleoclimate records document warm summers and increased precipitation. Finally, we show that the historical advances of the ice margin occurred during the past 200 years, likely in response to cooler summer temperatures.