Holocene Glacial History of Northwest and North Greenland

• Main Author: Søndergaard, Anne Sofie
• Format: Book
• Language: English
• Published: Århus Universitet 2020
• Subjects: Arctic; Greenland; Global warming; Ice Sheet; North Greenland
• Online Access: https://pure.au.dk/portal/en/publications/eb458dec-76f6-408e-b564-2c5789cb2e90

Present-day global warming is a threat to ice masses in the Arctic and estimated future temperatures in this region will be higher than the global average due to Arctic amplification. Mass loss from the Greenland Ice Sheet (GrIS) has increased significantly over the last decades as a consequence of rising atmospheric and ocean temperatures. In particular, the marine-based parts of the ice sheet have shown to be vulnerable to present-day warming. Ice marginal fluctuations of the ice sheet during the Holocene (last 11,700 years) is the most recent analogue for what might come in the future, and studying this period, can help extrapolate the current behaviour of the ice sheet into a long-term perspective. The northwest and north GrIS have shown a distinct sensitivity to current global warming, yielding widespread retreat and runoff. The northwest GrIS has been the largest contributor to sea level rise over the last decades, possibly due to its large marine-based area, and the north GrIS is expected to be one of the main contributors in the future as this region is currently undergoing dramatic changes. Despite this behaviour, research of and constraints on the Holocene glacial history in these regions were sparse just a few years ago. This PhD dissertation presents new extensive knowledge on ice marginal fluctuations and the sensitivity of the northwest and north GrIS to Holocene climate changes. Constraints were obtained using mainly 10Be exposure dating and radiocarbon dating. In addition, the first use of in-situ 14C exposure dating was applied in north Greenland, as the cold-based ice sheet complicated constraints in this region. Results on past ice marginal fluctuations were assessed with local and regional climate records. Our findings highlight an overall sensitivity of the GrIS to past climate changes. Especially, the large marine-based part of the ice sheet in northwest Greenland, shows distinct vulnerability to rising atmospheric temperatures at the onset of Holocene resulting in rapid ice retreat. We see ...