Response of Jakobshavn Isbræ, Gre

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• journal_title：Geology
• Contributor：Nicolás E. Young ; Jason P. Briner ; Heather A.M. Stewart ; Yarrow Axford ; Beata Csatho ; Dylan H. Rood ; Robert C. Finkel
• Publisher：Geological Society of America
• Date：2011-
• Format：text/html
• Language：en
• Identifier：10.1130/G31399.1
• journal_abbrev：Geology
• issn：0091-7613
• volume：39
• issue：2
• firstpage：131
• section：Articles

摘要

<p id="p-1">Rapid fluctuations in the velocity of Greenland Ice Sheet (GIS) outlet glaciers over the past decade have made it difficult to extrapolate ice-sheet change into the future. This significant short-term variability highlights the need for geologic records of preinstrumental GIS margin fluctuations in order to better predict future GIS response to climate change. Using p>10p>Be surface exposure ages and radiocarbon-dated lake sediments, we constructed a detailed chronology of ice-margin fluctuations over the past 10 k.y. for Jakobshavn Isbræ, Greenland's largest outlet glacier. In addition, we present new estimates of corresponding local temperature changes using a continuous record of insect (Chironomidae) remains preserved in lake sediments. We find that following an early Holocene advance just prior to 8 ka, Jakobshavn Isbræ retreated rapidly at a rate of ∼100 m yrp>−1p>, likely in response to increasing regional and local temperatures. Ice remained behind its present margin for ∼7 k.y. during a warm period in the middle Holocene with sustained temperatures ∼2 °C warmer than today, then the land-based margin advanced at least 2–4 km between A.D. 1500–1640 and A.D. 1850. The ice margin near Jakobshavn thus underwent large and rapid adjustments in response to relatively modest centennial-scale Holocene temperature changes, which may foreshadow GIS response to future warming. p>