TY - JOUR T1 - Multiple independent records of local glacier variability on Nuussuaq, West Greenland, during the Holocene JF - Quaternary Science Reviews Y1 - 2019 A1 - Schweinsberg, Avriel D. A1 - Briner, Jason P. A1 - Licciardi, Joseph M. A1 - Bennike, Ole A1 - Lifton, Nathaniel A. A1 - Graham, Brandon L. A1 - Young, Nicolás E. A1 - Schaefer, Joerg M. A1 - Zimmerman, Susan H. KW - Cosmogenic 10Be KW - Cosmogenic in situ 14C KW - Greenland KW - Holocene KW - lake sediment KW - Mountain glaciers KW - Neoglaciation AB - The sensitivity of mountain glaciers to small-scale climate fluctuations makes records of their past extent among the best proxies for identifying spatio-temporal climate variability. Here we build on the few existing Holocene records of local glacier change in Greenland by using three independent geochronological methods—proglacial lake sediment analysis, cosmogenic 10Be surface-exposure dating, and in situ 14C burial modeling—to reconstruct continuous records of Holocene glacier variability on Nuussuaq, West Greenland. 10Be ages of perched boulders indicate eastern Nuussuaq was deglaciated between ∼11.0 and 10.5 ka. Radiocarbon-dated sediments from two lakes on Nuussuaq contain mineral-rich layers between ∼9.6 and 9.0 and ∼8.7–8.0 cal ka BP that may be correlative with nearby ice sheet moraines deposited in the early Holocene. Multiple proxies for glacier size indicate frequent, high-amplitude glacier fluctuations superimposed on net glacier growth during the late Holocene, with significant ice expansion phases at ∼3.7 ka, 2.8 ka, and throughout the past ∼2 ka. Mean 10Be ages from five nested moraine crests confirm that local glacier extents on Nuussuaq culminated during both the Little Ice Age [∼1470 C.E. (n = 3) and 1750 C.E. (n = 3)] and the preceding centuries (∼520–1320 C.E.; n = 11). Results reveal that local glaciers on Nuussuaq episodically advanced and retreated at centennial timescales throughout the Holocene, most likely in response to regional climate changes in West Greenland superimposed on the progressive insolation-driven cooling trend in the Northern Hemisphere. Our new 10Be moraine chronologies coupled with other glacier-size proxies corroborate an emerging pattern of significant summer cooling and glacier expansion in the centuries prior to the Little Ice Age in the Arctic. VL - 215 UR - https://www.sciencedirect.com/science/article/pii/S0277379118308771 ER - TY - JOUR T1 - Holocene mountain glacier history in the Sukkertoppen Iskappe area, southwest Greenland JF - Quaternary Science Reviews Y1 - 2018 A1 - Schweinsberg, Avriel D. A1 - Briner, Jason P. A1 - Miller, Gifford H. A1 - Lifton, Nathaniel A. A1 - Bennike, Ole A1 - Graham, Brandon L. KW - Cosmogenic in situ 14C KW - Glacier fluctuations KW - Greenland KW - Holocene KW - lake sediment KW - Neoglaciation AB - Mountain glaciers and ice caps (GIC) independent of the Greenland Ice Sheet respond rapidly to climate variations and records of their past extent provide information on the natural envelope of climate variability. Here, we use a multi-proxy approach that combines proglacial lake sediment analysis, cosmogenic nuclide surface-exposure dating (in situ 10Be and 14C), and radiocarbon dating of recently ice-entombed moss to generate a centennial-scale record of Holocene GIC fluctuations in southwestern Greenland. Following local deglaciation ∼10-9 ka, sediments from proglacial Crash Lake record a glacier advance at ∼9 ka that is indistinguishable from nearby ice sheet moraines, implying a synchronous response of GIC and the Greenland Ice Sheet to a centennial-scale climate event. Following this local glacier advance, GIC experienced net recession until ∼4.6 ka. Radiocarbon ages of in situ moss (n = 29) and Crash Lake sediments reveal intervals of glacier expansion at ∼1.8, 1.2 and 0.7 ka that are superimposed on an overall trend of net glacier expansion throughout the late Holocene. In situ 14C concentrations from bedrock adjacent to radiocarbon-dated moss samples further constrain the duration of ice cover through the Holocene in this region. We find that our glacier-size proxy records during the past ∼4 ka are broadly consistent with relatively lower temperatures recorded in GISP2 and occur during, or following, intervals of volcanic perturbations. Thus, we speculate that volcanic activity, although less frequent and intense than in the early Holocene and during the Little Ice Age, may have led to centennial-scale variability imprinted on net glacier expansion due to decreasing summer insolation through the late Holocene. VL - 197 UR - https://www.sciencedirect.com/science/article/pii/S0277379118302531 ER - TY - JOUR T1 - Holocene climate and environmental history of East Greenland inferred from lake sediments JF - Journal of Paleolimnology Y1 - 2017 A1 - Lusas, Amanda R. A1 - Hall, Brenda L. A1 - Lowell, Thomas V. A1 - Kelly, Meredith A. A1 - Bennike, Ole A1 - Levy, Laura B. A1 - Honsaker, William KW - De Vries cycle KW - Glacially fed lakes KW - Greenland KW - Holocene KW - Paleoclimate AB - Prediction of future Arctic climate and environmental changes, as well as associated ice-sheet behavior, requires placing present-day warming and reduced ice extent into a long-term context. Here we present a record of Holocene climate and glacier fluctuations inferred from the paleolimnology of small lakes near Istorvet ice cap in East Greenland. Calibrated radiocarbon dates of organic remains indicate deglaciation of the region before ~10,500 years BP, after which time the ice cap receded rapidly to a position similar to or less extensive than present, and lake sediments shifted from glacio-lacustrine clay to relatively organic-rich gyttja. The lack of glacio-lacustrine sediments throughout most of the record suggests that the ice cap was similar to or smaller than present throughout most of the Holocene. This restricted ice extent suggests that climate was similar to or warmer than present, in keeping with other records from Greenland that indicate a warm early and middle Holocene. Middle Holocene magnetic susceptibility oscillations, with a ~200-year frequency in one of the lakes, may relate to solar influence on local catchment processes. Following thousands of years of restricted extent, Istorvet ice cap advanced to within 365 m of its late Holocene limit at ~AD 1150. Variability in the timing of glacial and climate fluctuations, as well as of sediment organic content changes among East Greenland lacustrine records, may be a consequence of local factors, such as elevation, continentality, water depth, turbidity, and seabirds, and highlights the need for a detailed spatial array of datasets to address questions about Holocene climate change. VL - 57 UR - http://link.springer.com/10.1007/s10933-017-9951-5 IS - 4 ER - TY - JOUR T1 - Local glaciation in West Greenland linked to North Atlantic Ocean circulation during the Holocene JF - Geology Y1 - 2017 A1 - Schweinsberg, Avriel D. A1 - Briner, Jason P. A1 - Miller, Gifford H. A1 - Bennike, Ole A1 - Thomas, Elizabeth K. AB - Recent observations indicate that ice-ocean interaction drives much of the recent increase in mass loss from the Greenland Ice Sheet; however, the role of ocean forcing in driving past glacier change is poorly understood. To extend the observational record and our understanding of the ocean-cryosphere link, we used a multi-proxy approach that combines new data from proglacial lake sediments, C-14-dated in situ moss that recently emerged from beneath cold-based ice caps, and Be-10 ages to reconstruct centennial-scale records of mountain glacier activity for the past similar to 10 k. y. in West Greenland. Proglacial lake sediment records and C-14 dating of moss indicate the onset of Neoglaciation in West Greenland at ca. 5 ka with substantial snowline lowering and glacier expansion at ca. 3.7 ka followed by additional ice expansion phases at ca. 2.9, ca. 1.7, and ca. 1.4 ka and during the Little Ice Age. We find that widespread glacier growth at ca. 3.7 ka in West Greenland coincides with marked cooling and reduced strength of the West Greenland Current in Disko Bugt. The transition to cooler ocean conditions at ca. 3.7 ka identified in Disko Bugt is registered by marine proxy data farther afield in East Greenland and on the northwestern Icelandic shelf, implying large-scale paleoceanographic changes across the North Atlantic during this interval. The similarity between glacier change on West Greenland and multiple marine and terrestrial records across the North Atlantic suggests that glaciers are strongly influenced by changes in ocean circulation and consequently implies that the ocean-cryosphere teleconnection is a persistent feature of the Arctic system. VL - 45 UR - http://geology.gsapubs.org/lookup/doi/10.1130/G38114 IS - 3 ER - TY - JOUR T1 - The deglaciation and neoglaciation of Upernavik Isstrøm, Greenland JF - Quaternary Research Y1 - 2013 A1 - Briner, Jason P. A1 - åkansson, Lena A1 - Bennike, Ole AB - We constrain the history of the Greenland Ice Sheet margin during the Holocene at Upernavik Isstrøm, a major ice stream in northwestern Greenland. Radiocarbon-dated sediment sequences from proglacial-threshold lakes adjacent to the present ice margin constrain deglaciation of the sites to older than 9.6 ± 0.1 ka. This age of deglaciation is confirmed with 10Be ages of 9.9 ± 0.1 ka from an island adjacent to the historical ice position. The lake sediment sequences also constrain the ice margin to have been less extensive than it is today for the remainder of the Holocene until ~ 1100 to ~ 700 yr ago, when it advanced into two lake catchments. The ice margin retreated back out of these lake catchments in the last decade. The early Holocene deglaciation in Melville Bugt, one of few locations around Greenland where a vast stretch of the current ice margin is marine-based, preceded deglaciation in most other parts of Greenland. Earlier deglaciation in this ice-sheet sector may have been caused by additional ablation mechanisms that apply to marine-based ice margins. Furthermore, despite ice-sheet models depicting this sector of Greenland as relatively stable throughout the Holocene, our data indicate a > 20 km advance-retreat cycle within the last millennium. VL - 80 UR - https://doi.org/10.1016/j.yqres.2013.09.008 IS - 03 ER - TY - JOUR T1 - Late Holocene expansion of Istorvet ice cap, Liverpool Land, east Greenland JF - Quaternary Science Reviews Y1 - 2013 A1 - Lowell, Thomas V. A1 - Hall, Brenda L. A1 - Kelly, Meredith A. A1 - Bennike, Ole A1 - Lusas, Amanda R. A1 - Honsaker, William A1 - Smith, Colby A. A1 - Levy, Laura B. A1 - Travis, Scott A1 - Denton, George H. AB - The Greenland Ice Sheet is undergoing dynamic changes that will have global implications if they continue into the future. In this regard, an understanding of how the ice sheet responded to past climate changes affords a baseline for anticipating future behavior. Small, independent ice caps adjacent to the Greenland Ice Sheet (hereinafter called “local ice caps”) are sensitive indicators of the response of Greenland ice-marginal zones to climate change. Therefore, we reconstructed late Holocene ice-marginal fluctuations of the local Istorvet ice cap in east Greenland, using radiocarbon dates of subfossil plants, 10Be dates of surface boulders, and analyses of sediment cores from both threshold and control lakes. During the last termination, the Istorvet ice cap had retreated close to its maximum Holocene position by ∼11,730 cal yr BP. Radiocarbon dates of subfossil plants exposed by recent recession of the ice margin indicate that the Istorvet cap was smaller than at present from AD 200 to AD 1025. Sediments from a threshold lake show no glacial input until the ice cap advanced to within 365 m of its Holocene maximum position by ∼AD 1150. Thereafter the ice cap remained at or close to this position until at least AD 1660. The timing of this, the most extensive of the Holocene, expansion is similar to that recorded at some glaciers in the Alps and in southern Alaska. However, in contrast to these other regions, the expansion in east Greenland at AD 1150 appears to have been very close to, if not at, a maximum Holocene value. Comparison of the Istorvet ice-cap fluctuations with Holocene glacier extents in Southern Hemisphere middle-to-high latitude locations on the Antarctic Peninsula and in the Andes and the Southern Alps suggests an out-of-phase relationship. If correct, this pattern supports the hypothesis that a bipolar see-saw of oceanic and/or atmospheric circulation during the Holocene produced asynchronous glacier response at some localities in the two polar hemispheres. VL - 63 UR - http://www.sciencedirect.com/science/article/pii/S0277379112004830 N1 - id: 2290 JO - Late Holocene expansion of Istorvet ice cap, Liverpool Land, east Greenland ER -