Multi-phased deglaciation of south and southeast Greenland controlled by climate and topographic setting. (15th August 2020)

• Record Type: Journal Article
• Authors: Levy, Laura B.; Larsen, Nicolaj K.; Knudsen, Mads F.; Egholm, David L.; Bjørk, Anders A.; Kjeldsen, Kristian K.; Kelly, Meredith A.; Howley, Jennifer A.; Olsen, Jesper; Tikhomirov, Dmitry; Zimmerman, Susan R.H.; Kjær, Kurt H.
• Is Part Of: Quaternary science reviews. Volume 242(2020)
• Publication Date: 2020-08-15
• Subjects: Greenland Ice sheet -- 10Be dating -- Deglaciation; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2020.106454
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: To put recent Greenland Ice Sheet (GrIS) ice loss into a longer-term context, we must understand its behavior during late-glacial and Early Holocene warming. Previous results seem to suggest that there is a large contrast in the timing of deglaciation between South and Southeast Greenland. However, because of lack of available data, in particular in Southeast Greenland, it is difficult to assess how the ice sheet responded to major late-glacial and Early Holocene climate changes. In this study, we use 41 new 10 Be ages to constrain the deglaciation chronology in 12 new locations from the coast to the present ice margin in South and Southeast Greenland. We find that South Greenland (south of 61.5°N) deglaciated between ∼14.8 and 11.9 ka, whereas Southeast Greenland (61.5°N to 68.2°N) deglaciated between ∼11.4 and 11.3 ka. The deglaciation of the coastal, low-intermediate topography in South Greenland coincides with increased air surface temperatures during the Bølling-Allerød with fjords continuing to deglaciate into the Early Holocene. In contrast, the ice sheet persisted at the coast until the late-glacial and Early Holocene in Southeast Greenland, likely because of increased precipitation in the high alpine topography and fjord geometry and bathymetry (e.g. width of fjords and presence of sills). This multi-phased deglaciation demonstrates a contrasting response of the southern GrIS to changes in climate and variations in topographic setting, and that the spatial deglaciation of the GrIS was complex and likely did not respond to a single external climate forcing. Highlights: Deglaciation began in South Greenland by 14.8 ka coeval with rising air temperature. Warm Atlantic water likely drove deglaciation during the Younger Dryas. Ice retreated from Southeast Greenland coast by 11.3 ka when air temperatures rose. Evidence of a Neoglacial advance occurs in Southeast Greenland by ∼1.9 ka. Local climate, topography and fjord geometry/bathymetry likely mediated ice retreat.