Deglaciation of the Greenland and Laurentide ice sheets interrupted by glacier advance during abrupt coolings

Young, Nicolás E.; Briner, Jason P.; Miller, Gifford H.; Lesnek, Alia J.; Crump, Sarah E.; Thomas, Elizabeth K.; Pendleton, Simon L.; Cuzzone, Joshua; Lamp, Jennifer L.; Zimmerman, Susan; Caffee, Marc W.; Schaefer, Joerg M.

doi:10.1016/j.quascirev.2019.106091

Cited by 64 publications

(93 citation statements)

References 95 publications

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“…Young et al . 2020) we present 10 Be ages without correcting for glacial isostatic uplift, similar to most other 10 Be studies from Greenland (e.g. Rinterknecht et al .…”

Section: Methodssupporting

confidence: 87%

“…2011b; Young et al . 2020). However, this approach requires that the moraines are tightly spaced and/or continuous so that they can be correlated from one fjord to another.…”

Section: Resultsmentioning

confidence: 99%

“…2016; Young et al . 2020). Individual 10 Be ages are presented with their 1‐sigma analytical uncertainties, which include the uncertainty of the blank correction (Table 1).…”

Section: Methodsmentioning

confidence: 99%

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Contrasting modes of deglaciation between fjords and inter‐fjord areas in eastern North Greenland

Larsen

Søndergaard

Levy

et al. 2020

Boreas

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Knowledge about the deglaciation history of the Greenland Ice Sheet (GrIS) is important to put the recent observations of ice loss into a longer‐term perspective. In southern Greenland, the deglaciation history is generally well constrained. In this study, we use 43 new 10Be surface exposure ages combined with existing minimum‐limiting 14C ages to constrain the deglaciation history of eastern North Greenland, including the three major fjord systems – Independence Fjord, Hagen Fjord and Danmark Fjord. The 10Be ages are generally scattered and many of the samples are significantly older than expected, with pre‐LGM ages being a result of inheritance from previous exposures. By using a Bayesian statistical approach to combine the new 10Be ages and existing 14C ages, we are able to constrain the deglaciation history. We find that the outer coast and deep fjords were rapidly deglaciated between ̃11 and 10 ka. Subsequently, the deglaciation progressed far inland up the fjords, probably as a result of increased summer surface temperatures and subsurface ocean temperatures during the Holocene Thermal Maximum. The rapid retreat of the Middle Holocene slowed when the ice sheet became land‐based in the central and southern part of the study area where the ice margin first reached its present extent by ̃6.7 ka. As the onset of Neoglacial ice advance had already commenced at ̃5 ka this limits the period when the ice margin could retreat farther inland and it probably remained within max. 30–40 km of its present extent. The contrasting behaviour between the fjords and inter‐fjord areas shows a clear topographic effect on the stability of the GrIS. These results inform how the GrIS may respond to a warmer climate in various topographic settings and may provide useful constraints for future ice‐sheet models.

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“…Young et al . 2020) we present 10 Be ages without correcting for glacial isostatic uplift, similar to most other 10 Be studies from Greenland (e.g. Rinterknecht et al .…”

Section: Methodssupporting

confidence: 87%

“…2011b; Young et al . 2020). However, this approach requires that the moraines are tightly spaced and/or continuous so that they can be correlated from one fjord to another.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Contrasting modes of deglaciation between fjords and inter‐fjord areas in eastern North Greenland

Larsen

Søndergaard

Levy

et al. 2020

Boreas

View full text Add to dashboard Cite

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“…In addition, we make no correction for the potential effects of isostatic rebound on nuclide production because both the production-rate calibration sites and sites of unknown age have experienced similar exposure and uplift histories (i.e. the correction is "built in"; Young et al, 2020aYoung et al, , 2020b. Individual 10 Be and in situ 14 C ages are presented and discussed with 1s analytical uncertainties, and moraine ages exclude the 10 Be production-rate https://doi.org/10.5194/cp-2020-111 Preprint.…”

Section: Be and In Situ 14 C Age Calculationsmentioning

confidence: 99%

“…Direct evidence of former GrIS maxima is found in offshore sedimentary deposits (e.g. Ó Cofaigh et al, 2013;Knutz et al, 2019), and the pattern of retreat from the most recent ice-sheet maximum can be reconstructed in detail through a combination of well-dated marine and terrestrial sedimentary archives (Bennike and Bjork, 2002;Funder et al, 2011;Kelley et al, 2013;Hogan et al, 2016;Jennings et a., 2017;Young et al, 2020a). Reconstructing the size and timing of ice-sheet minima, however, is extremely challenging because terrestrial evidence relating to ice-sheet minima has been overrun and destroyed by subsequent glacier re-expansion or resides in a largely inaccessible environment beneath modern glacier footprints.…”

Section: Introductionmentioning

confidence: 99%

Cosmogenic isotope measurements from recently deglaciated bedrock as a new tool to decipher changes in Greenland Ice Sheet size

Young

Lesnek

Cuzzone

et al. 2020

Preprint

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Abstract. During the middle to late Holocene (8.2 ka BP to present), the Greenland Ice Sheet (GrIS) was smaller than its current configuration. Determining the exact dimensions of the Holocene ice-sheet minimum and the duration that the ice margin rested inboard of its current position remains challenging. Contemporary retreat of the GrIS from its historical maximum extent in southwestern Greenland is exposing a landscape that holds clues regarding the configuration and timing of past ice-sheet minima. To quantify the duration of the time the GrIS margin was near its modern extent we develop a new technique on Greenland that utilizes in situ cosmogenic 10Be-14C-26Al in bedrock samples that have become ice free only in the last few decades by the retreating ice-sheet margin at Kangiata Nunaata Sermia (n = 12 sites; KNS), southwest Greenland. To maximize the utility of this approach, we refine the deglaciation history of the region with stand-alone 10Be measurements (n = 49) and traditional 14C ages from sedimentary deposits contained in proglacial-threshold lakes. We combine our reconstructed ice-margin history in the KNS region with additional geologic records from southwestern Greenland and recent model simulations of GrIS change, to constrain the timing of the GrIS minimum in southwest Greenland, the magnitude of Holocene inland GrIS retreat, and explore the regional climate history influencing Holocene ice-sheet behavior. Our 10Be-14C-26Al measurements reveal that 1) KNS retreated behind its modern margin just before 10 ka, but likely stabilized near the present GrIS margin for several thousand years before retreating farther inland, and 2) pre-Holocene 10Be detected in several of our sample sites is most easily explained by several thousand years of surface exposure during the Last Interglaciation. Moreover, our new results indicate that the minimum extent of the GrIS likely occurred after ~ 5 ka, and the GrIS margin may have approached its eventual historical maximum extent as early as ~ 2 ka. Recent simulations of GrIS change are able to match the geologic record of ice-sheet change in regions dominated by surface mass balance, but produce a poorer model-data fit in areas influenced by oceanic and dynamic processes. Simulations that achieve the best model-data fit suggest that inland retreat of the ice margin driven by early to middle Holocene warmth may have been mitigated by increased precipitation. Triple 10Be-14C-26Al measurements in recently deglaciated bedrock provide a new tool to help decipher the duration of smaller-than-present ice over multiple timescales. Modern retreat of the GrIS margin in southwest Greenland is revealing a bedrock landscape that was also exposed during the migration of the GrIS margin towards its Holocene minimum extent, but has yet to tap into a landscape that remained ice covered throughout the entire Holocene.

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Climatic control on the retreat of the Laurentide Ice Sheet margin in easternmost Québec–Labrador (Canada) revealed by cosmogenic nuclide exposure dating

Couette

Ghienne

Lajeunesse

et al. 2023

J Quaternary Science

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The Laurentide Ice Sheet (LIS) was the largest ice sheet in the Northern Hemisphere during the last glacial cycle. The effects of its demise on global climate and sea‐level changes during the subsequent deglaciation are unequivocal. Understanding the interplay between ice sheets and long‐term or short‐term (e.g. abrupt) climatic events is therefore crucial for predicting future rates of ice sheet melting and their potential contribution to sea‐level changes. Here, we present 37 new 10Be surface exposure ages from easternmost Québec–Labrador that allow us to identify close ties between regional deglaciation history and climate. These results reveal that the LIS was disconnected from the Newfoundland Ice Cap by ~14.1 ka. Samples collected from moraine boulders indicate that this event was followed by five major stillstands and/or readvance stages of the LIS margin. Integrating our new moraine ages with those of earlier studies allows us to depict a temporal framework including events at ~12.9, ~11.5, ~10.4, ~9.3 and ~8.4–8.2 ka. These moraine ages highlight a strong sensitivity of the LIS to temperature changes in the Northern Hemisphere, as the documented continental ice margin stabilizations coincide with abrupt cooling events recorded in Greenland ice cores. These observations support the idea of a negative feedback mechanism induced by meltwater forcings into the North Atlantic Ocean which, in turn, provoked repeated cold reversals during the Younger Dryas and early Holocene.

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Deglaciation of the Greenland and Laurentide ice sheets interrupted by glacier advance during abrupt coolings

Cited by 64 publications

References 95 publications

Contrasting modes of deglaciation between fjords and inter‐fjord areas in eastern North Greenland

Contrasting modes of deglaciation between fjords and inter‐fjord areas in eastern North Greenland

Cosmogenic isotope measurements from recently deglaciated bedrock as a new tool to decipher changes in Greenland Ice Sheet size

Climatic control on the retreat of the Laurentide Ice Sheet margin in easternmost Québec–Labrador (Canada) revealed by cosmogenic nuclide exposure dating

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