Establishing the timing of maximum Holocene warmth in the Arctic is critical for understanding global climate system response to external forcing. In Greenland, challenges in obtaining climate records that span the full Holocene have hampered efforts to robustly identify when the Holocene Thermal Maximum occurred. Reconstructing land-based ice sheet history can fill this gap because these ice sheet regions respond sensitively to summer temperature. We synthesize new and published 10Be and 14C ages from southwest Greenland to map Greenland ice sheet margin positions from 12 to 7 ka and calculate retreat rates from 12 to 0 ka. We found that maximum Greenland ice sheet recession occurred between ~10.4 and 9.1 ka. Our reconstruction suggests that summer air temperatures in southwest Greenland were highest from ~10.4 to 9.1 ka, providing support for an early regional Holocene Thermal Maximum. These results can serve as benchmarks for comparison with ice sheet and climate model simulations.
Bibliographical noteFunding Information:
Two anonymous reviewers provided comments that strengthened this manuscript. This research was supported by NSF grants ARC-1504267 and ARC-1417783 to J. P. B. and NSF grants ARC-1503959 and ARC-1417675 to N. E. Y. DEMs were provided by the Polar Geospatial Center under NSF-OPP awards 1043681, 1559691, and 1542736. Geologic samples are archived at the University at Buffalo Department of Geology. All data presented in this paper are publicly available at the NOAA National Centers for Environment Information (https://www.ncdc.noaa.gov/paleo-search/study/26450).
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