Late-glacial grounding line retreat in the northern Ross Sea, Antarctica

Goehring, Brent M.; Balco, Greg; Todd, Claire; Moening-Swanson, Isaac; Nichols, Keir

doi:10.1130/g45413.1

Cited by 33 publications

(35 citation statements)

References 26 publications

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“…Subsequent grounding line retreat north of Ross Island was achieved by ∼8.6 ka and a modern configuration established by ∼2-4 ka (Anderson et al, 2014;McKay et al, 2016). Outlet and valley glaciers along the Northern Victoria Land sector (Reeves, Priestley, and Tucker, Aviator, Campbell glaciers, respectively) began thinning at ∼17 ka and the majority of thinning ceased by ∼7.5 ka, broadly coincident with a linear rise in sea level and ocean temperatures throughout deglaciation (Baroni and Hall, 2004;Johnson et al, 2008;Smellie et al, 2018;Goehring et al, 2019;Rhee et al, 2019). In contrast, outlet glaciers covering a large swath of the TAM from Southern Victoria Land to Southern TAM, experienced episodic thinning during the early-mid Holocene, likely due to local topographic effects associated with Marine Ice Sheet Instability (MISI) (Jones et al, 2015;Spector et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Mid-Holocene thinning of David Glacier, Antarctica: Chronology and Controls

Stutz¹,

Mackintosh²,

Norton³

et al. 2020

Preprint

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Abstract. Quantitative satellite observations provide a comprehensive assessment of ice sheet mass loss over the last four decades, but limited insights into long-term drivers of ice sheet change. Geological records can extend the observational record and aid our understanding of ice sheet–climate interactions. Here we present the first millennial-scale reconstruction of David Glacier, the largest East Antarctic outlet glacier in Victoria Land. We use surface exposure dating of glacial erratics deposited on nunataks to reconstruct changes in ice surface elevation through time. We then use numerical modelling experiments to determine the drivers of glacial thinning. Thinning profiles derived from 45 10Be and 3He surface exposure ages show that David Glacier experienced rapid thinning up to 2 m/yr during the mid-Holocene (~ 6,500 years ago). Thinning stabilised at 6 kyr, suggesting initial formation of the Drygalski Ice Tongue at this time. Our work, along with terrestrial cosmogenic nuclide records from adjacent glaciers, shows simultaneous glacier thinning in this sector of the Transantarctic Mountains occurred ~ 3 kyr after the retreat of marine-based grounded ice in the western Ross Embayment. The timing and rapidity of the reconstructed thinning at David Glacier is similar to reconstructions in the Amundsen and Weddell embayments. In order to identify the potential causes of these rapid changes along the David Glacier, we use a glacier flow line model designed for calving glaciers and compare modelled results against our geological data. We show that glacier thinning and marine-based grounding line retreat is initiated by interactions between enhanced sub-ice shelf melting and reduced lateral buttressing, leading to Marine Ice Sheet Instability. Such rapid glacier thinning events are not captured in continental or sector-scale numerical modelling reconstructions for this period. Together, our chronology and modelling suggest a ~ 2,000-year period of dynamic thinning in the recent geological past.

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Section: Introductionmentioning

confidence: 99%

Mid-Holocene thinning of David Glacier, Antarctica: Chronology and Controls

Stutz¹,

Mackintosh²,

Norton³

et al. 2020

Preprint

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“…Throughout this period, Antarctic mass balance changes were driven by a wide spectrum of external forcings: changes in atmospheric temperatures, accumulation rates, oceanic conditions and sea level (Tigchelaar et al, 2018a). There is substantial spatial variability in the sensitivity of the AIS to these forcings, as indicated, for example, by surface exposure chronologies since the Last Glacial Maximum (LGM) (e.g., RAISED Consortium et al, 2014;Hillenbrand et al, 2014;Spector et al, 2017;Goehring et al, 2019). So far, however, the relative contributions of different external drivers of past AIS vari-ability and their synergies have not been quantified in modeling studies.…”

Section: Introductionmentioning

confidence: 99%

“…Looking at individual forcings allows us to identify which are important, which need modeling improvement, and how they might interact nonlinearly in future Antarctic change. These simulations can also be used to aid in interpretation of the rich AIS deglaciation record (RAISED Consortium et al, 2014;Hillenbrand et al, 2014;Spector et al, 2017;Goehring et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Nonlinear response of the Antarctic Ice Sheet to late Quaternary sea level and climate forcing

et al. 2019

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Abstract. Antarctic ice volume has varied substantially during the late Quaternary, with reconstructions suggesting a glacial ice sheet extending to the continental shelf break and interglacial sea level highstands of several meters. Throughout this period, changes in the Antarctic Ice Sheet were driven by changes in atmospheric and oceanic conditions and global sea level; yet, so far modeling studies have not addressed which of these environmental forcings dominate and how they interact in the dynamical ice sheet response. Here, we force an Antarctic Ice Sheet model with global sea level reconstructions and transient, spatially explicit boundary conditions from a 408 ka climate model simulation, not only in concert with each other but, for the first time, also separately. We find that together these forcings drive glacial–interglacial ice volume changes of 12–14 ms.l.e., in line with reconstructions and previous modeling studies. None of the individual drivers – atmospheric temperature and precipitation, ocean temperatures, or sea level – single-handedly explains the full ice sheet response. In fact, the sum of the individual ice volume changes amounts to less than half of the full ice volume response, indicating the existence of strong nonlinearities and forcing synergy. Both sea level and atmospheric forcing are necessary to create full glacial ice sheet growth, whereas the contribution of ocean melt changes is found to be more a function of ice sheet geometry than climatic change. Our results highlight the importance of accurately representing the relative timing of forcings of past ice sheet simulations and underscore the need for developing coupled climate–ice sheet modeling frameworks that properly capture key feedbacks.

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“…Collectively these data suggest glacier advance and/or fluctuations at close to maximum thickness from ~14-8 kyr BP. At Lake Wellman, Magnis Valley, and Bibra/Dubris Valleys ice was at its maximum limit at 9.5 kyr BP, a time when large outlet glaciers in the southern TAM were thinning at their mouths (Todd et al, 2010;Spector et al, 2017), and the grounding line of the Ross Sea Ice Sheet was retreating southwards (Hall et al, 2013;Goehring et al, 2019b). Dates of maximum thickness are not demonstrably different between the three sites on Hatherton Glacier, which also differs from the diachronous behavior of upper and middle Reedy Glacier (Todd et al, 2010), although the sizes of these glaciers and the distance between sites are very different.…”

Section: Summary Of Geochronologic Constraintsmentioning

confidence: 99%

Holocene thinning and grounding-line retreat of Darwin and Hatherton Glaciers, Antarctica

Hillebrand

Stone

Koutnik

et al. 2020

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Abstract. We present exposure ages of glacial deposits at three locations alongside Darwin Glacier and its tributary Hatherton Glacier that record several hundred meters of late Pleistocene to early Holocene thickening relative to present. As the grounding-line of the Ross Sea Ice Sheet retreated rapidly southward, Hatherton Glacier thinned steadily from about 9 kyr BP until about 3 kyr BP. Our data are equivocal about the maximum thickness and mid-to-early Holocene history at the mouth of Darwin Glacier, allowing for two possible deglaciation scenarios: (1) ~500 m of steady thinning from 9 kyr BP to 3 kyr BP, similar to Hatherton Glacier, or (2) ~950 m of thinning, with a rapid pulse of ~600 m thinning at around 5 kyr BP. We test these two scenarios using a 1.5-dimensional flowband model of Darwin and Hatherton Glaciers, forced by ice-thickness changes at the mouth of Darwin Glacier and evaluated by fit to the chronology of deposits at Hatherton Glacier. Our modeling shows that the constraints from Hatherton Glacier are consistent with the interpretation that the mouth of Darwin Glacier thinned steadily by ~500 m from 9 kyr BP to 3 kyr BP; rapid pulses of thinning at the mouth of Darwin Glacier are ruled out by the data at Hatherton Glacier. This contrasts with some of the available records from the mouths of other outlet glaciers in the Transantarctic Mountains, many of which thinned by hundreds of meters over roughly a one-thousand-year period in the early Holocene. The deglaciation histories of Darwin and Hatherton Glaciers are best matched by a steady decrease in catchment area through the Holocene, suggesting that Byrd and/or Mulock glaciers may have captured roughly half of the catchment area of Darwin and Hatherton Glaciers during the last deglaciation. An ensemble of three-dimensional ice-sheet model simulations suggest that Darwin and Hatherton Glaciers are strongly buttressed by convergent flow with ice from neighboring Byrd and Mulock glaciers, and by lateral drag past Minna Bluff, which could have led to a pattern of retreat distinct from other glaciers throughout the Transantarctic Mountains.

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Late-glacial grounding line retreat in the northern Ross Sea, Antarctica

Cited by 33 publications

References 26 publications

Mid-Holocene thinning of David Glacier, Antarctica: Chronology and Controls

Mid-Holocene thinning of David Glacier, Antarctica: Chronology and Controls

Nonlinear response of the Antarctic Ice Sheet to late Quaternary sea level and climate forcing

Holocene thinning and grounding-line retreat of Darwin and Hatherton Glaciers, Antarctica

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