气候变化领域集成服务门户(CCPortal): Local glaciers record delayed peak Holocene warmth in south Greenland

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DOI	10.1016/j.quascirev.2020.106421
	Local glaciers record delayed peak Holocene warmth in south Greenland
	Larocca L.J.; Axford Y.; Bjørk A.A.; Lasher G.E.; Brooks J.P.
发表日期	2020
ISSN	0277-3791
卷号	241
英文摘要	Local glaciers and ice caps (GICs) respond sensitively and quickly, on the scale of decades to centuries, to climate variations. Continuous records of past fluctuations in GIC size provide information on the timing and magnitude of Holocene climate shifts, and a longer-term perspective on 21st century glacier retreat. Although there is broad-scale agreement on millennial-scale trends in Holocene climate variability and fluctuations in local GICs in Greenland, regional variations are only loosely constrained. Here we present three Holocene proglacial lake sediment records from South Greenland, an area with abundant local glaciers but few Holocene-length paleoclimate records. In addition, we use geospatial analysis to model past equilibrium-line altitudes (ELAs) and thereby constrain the magnitude of ablation-season temperature change during the warmest and coolest periods of the Holocene. Physical and geochemical sedimentary characteristics show that two of the proglacial lakes continued to receive glacial meltwater input until ∼7.3 and ∼7.1 ka BP. The survival of local glaciers implies that South Greenland remained relatively cool, and that summer temperatures gradually warmed, but did not warm well beyond 1.2 °C above present in the early Holocene. In the mid-Holocene, from ∼7.1 to 5.5 ka BP, organic sedimentation at these two sites indicates that local glaciers became very small, or more likely melted away completely. The glaciers within the third lake's catchment melted away prior to ∼5.2 ka BP, as sediments deposited earlier in the Holocene could not be dated at this site. We estimate that summer temperatures increased by at least 1.2–1.8 °C above present by ∼7.3–7.1 ka BP. Our results are consistent with other observations that suggest a north-to-south gradient in the timing of Holocene thermal maximum conditions, with southern Greenland experiencing a delayed warming relative to other regions in Greenland. As summer temperatures cooled in the Neoglacial, our records show that sustained glacier regrowth began ∼3.1 ka BP with glaciers in the southernmost catchment, which at present, receive the most precipitation. In the other two catchments, which host smaller glaciers in a drier environment, regrowth began at ∼1.3 and ∼1.2 ka BP, the timing of which is in agreement with other glacial records from the Arctic Atlantic region. Local glaciers reached their maximum late Holocene extents during a cooler, second phase of the Little Ice Age (LIA) ∼0.2-0.1 ka BP, that we estimate was at least 0.4–0.9 °C cooler than present. Overall, these findings improve understanding of the spatio-temporal dynamics of Holocene glacier and climate change in Greenland, potentially yielding valuable information about their future response. © 2020 Elsevier Ltd
英文关键词	Equilibrium-line altitudes; Greenland; Holocene thermal maximum; Lake sediments; Little ice age; Mountain glaciers; Paleotemperatures
语种	英语
scopus关键词	Catchments; Cooling systems; Glacial geology; Lakes; Runoff; Sediments; Equilibrium line altitudes; Geo-spatial analysis; Holocene climate variability; Holocene thermal maximums; Paleoclimate records; Sedimentary characteristics; Spatio-temporal dynamics; Summer temperature; Climate change; climate variation; glacier; Holocene; Little Ice Age; sedimentation; spatiotemporal analysis; warming; Arctic; Greenland
来源期刊	Quaternary Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151411
作者单位	Department of Earth and Planetary Sciences, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United States; Department of Geography, University of Copenhagen, Øster Voldgade 10, Copenhagen K, 1350, Denmark; Department of Geology and Environmental Science, University of Pittsburgh, 4107 O'Hara Street, Pittsburgh, PA 15260, United States
推荐引用方式 GB/T 7714	Larocca L.J.,Axford Y.,Bjørk A.A.,et al. Local glaciers record delayed peak Holocene warmth in south Greenland[J],2020,241.
APA	Larocca L.J.,Axford Y.,Bjørk A.A.,Lasher G.E.,&Brooks J.P..(2020).Local glaciers record delayed peak Holocene warmth in south Greenland.Quaternary Science Reviews,241.
MLA	Larocca L.J.,et al."Local glaciers record delayed peak Holocene warmth in south Greenland".Quaternary Science Reviews 241(2020).