Ice mass loss sensitivity to the Antarctic ice sheet basal thermal state

Dawson, Eliza; Schroeder, Dustin M.; Chu, Winnie; Mantelli, Elisa; Seroussi, Hélène

doi:10.1038/s41467-022-32632-2

Cited by 15 publications

(28 citation statements)

References 66 publications

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“…The basal thermal state can also transition over time via thawing or refreezing (Engelhardt, 2004; Wilch & Hughes, 2000). While both basal thawing and refreezing can modulate ice flow, recent analysis shows that the effect of thawing could lead to significantly increased ice mass loss in Adélie‐George V Land (Dawson et al., 2022). These findings suggest that the current ice configuration of the region could be sensitive to changes in subglacial conditions.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Basal Thermal Conditions Underpinning the Adélie‐George V Coast, East Antarctica

Dawson,

Schroeder,

Chu

et al. 2024

Geophysical Research Letters

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Adélie‐George V Land in East Antarctica, encompassing the vast Wilkes Subglacial Basin, has a configuration that could be prone to ice sheet instability: the basin's retrograde bed slope could make its marine terminating glaciers vulnerable to warm seawater intrusion and irreversible retreat under predicted climate forcing. However, future projections are uncertain, due in part to limited subglacial observations near the grounding zone. Here, we develop a novel statistical approach to characterize subglacial conditions from radar sounding observations. Our method reveals intermixed frozen and thawed bed within 100 km of the grounding‐zone near the Wilkes Subglacial Basin outflow, and enables comparisons to ice sheet model‐inferred thermal states. The signs of intermixed or near thawed conditions raises the possibility that changes in basal thermal state could impact the stability of Adélie‐George V Land, adding to the region's potentially vulnerable topographic configuration and sensitivity to ocean forcing driven grounding line retreat.

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Section: Introductionmentioning

confidence: 99%

Heterogeneous Basal Thermal Conditions Underpinning the Adélie‐George V Coast, East Antarctica

Dawson,

Schroeder,

Chu

et al. 2024

Geophysical Research Letters

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“…Although the shape of lakes is not a reliable measure of the intensity of glacial erosion, we compare elongation of lakes in regions that contained paleo‐ice streams (Húnaflói and Bakkaheiði) with a region that did not contain a paleo‐ice stream (Vestfirðir). Studies of modern ice streams in Antarctica and Greenland provide evidence for warm‐based ice (e.g., Beem et al, 2010; Dawson et al, 2022; Fahnestock et al, 2001; Keisling et al, 2014). Ice streams are important mass balance regulators within ice sheets via transport of ice to the ocean for calving or to lower elevations for melting, and they are also significant agents of erosion at ice sheet beds that regulate sediment transport to ice‐sheet margins (Evans et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Mastro,

Principato,

Sobel

et al. 2023

Earth Surf Processes Landf

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Glacial erosion rates on the Iceland landscape throughout the Pleistocene are not well quantified. Ice scour lakes provide an opportunity to investigate glacial erosive activity and relative intensity because they commonly form in areas beneath ice sheets due to intense quarrying. This study evaluates ice scour lake morphology and density as a potential proxy for paleo‐ice flow direction and basal thermal regime for parts of the Iceland Ice Sheet. Using GIS analysis, properties of ice scour lakes are examined in regions that experienced different rates of ice flow during and following the Last Glacial Maximum (LGM), as interpreted from streamlined subglacial landforms. The primary input datasets were topographic, hydrologic and bedrock data. Lake distribution and morphology were quantified for all natural lakes of Iceland (n = 30 169), with close examination of three 400 km2 sub‐regions in Vestfirðir (n = 904), Húnaflói (n = 69) and Bakkaheiði (n = 232). Lake distribution parameters include density, packing and centroid elevation. PolyMorph‐2D was used to quantify lake morphology including orientation, area and elongation ratio. Ice scour lake density, packing and elevation were all greatest on Vestfirðir. The high density and packing of lakes across Vestfirðir suggests unique ice dynamics relative to the other two sub‐regions, and multidirectional flow of lake axes supports the presence of an independent ice cap covering Vestfirðir. Differential intensity of glacial erosion interpreted from regions of high and low lake density on Bakkaheiði supports a proposed ice divide in Northeast Iceland. The orientation of lakes align with the flow directions of proposed LGM ice streams in Northern and Northeast Iceland. Ice scour lakes were most elongate on average on Bakkaheiði, which supports fast ice flow. Improving understanding of former ice sheet basal thermal regime and paleo‐ice flow velocity serves to inform modern controls on ice sheet stability and ice sheet basal processes.

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“… Influences on ice‐sheet dynamics showing basins over (a) geothermal heat flux estimated from geophysical data (Lösing & Ebbing, 2021) (b) surface ice sheet velocity derived from InSAR phase mapping (Mouginot et al., 2019) (c) inferred basal friction coefficient derived by inverting for basal conditions using the Ice sheet and Sea level System Model (Dawson et al., 2022) and (d) subglacial hydrology, including subglacial lakes (Livingstone et al., 2022), and a modern‐day drainage network (Le Brocq et al., 2013). Numbers indicate ice stream systems with sedimentary basins beneath fast flowing ice including 1‐Mercer and Whillans, 2‐Bindschadler and MacAyeal, 3‐Institute, 4‐Academy and Support Force, 5‐Jutulstraumen, 6‐West and Central Ragnhild, 7‐Cook.…”

Section: Implications For Antarctic Ice Sheet Dynamicsmentioning

confidence: 99%

Antarctic Sedimentary Basins and Their Influence on Ice‐Sheet Dynamics

Aitken,

Li,

Kulessa

et al. 2023

Reviews of Geophysics

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Knowledge of Antarctica’s sedimentary basins builds our understanding of the coupled evolution of tectonics, ice, ocean, and climate. Sedimentary basins have properties distinct from basement‐dominated regions that impact ice‐sheet dynamics, potentially influencing future ice‐sheet change. Despite their importance, our knowledge of Antarctic sedimentary basins is restricted. Remoteness, the harsh environment, the overlying ice sheet, ice shelves and sea ice all make fieldwork challenging. Nonetheless, in the past decade the geophysics community has made great progress in internationally coordinated data collection and compilation with parallel advances in data processing and analysis supporting a new insight into Antarctica’s subglacial environment. Here, we summarize recent progress in understanding Antarctica’s sedimentary basins. We review advances in the technical capability of radar, potential fields, seismic and electromagnetic techniques to detect and characterize basins beneath ice and advances in integrated multi‐data interpretation including machine‐learning approaches. These new capabilities permit a continent‐wide mapping of Antarctica’s sedimentary basins and their characteristics, aiding definition of the tectonic development of the continent. Crucially, Antarctica’s sedimentary basins interact with the overlying ice sheet through dynamic feedbacks that have the potential to contribute to rapid ice‐sheet change. Looking ahead, future research directions include techniques to increase data coverage within logistical constraints, and resolving major knowledge gaps, including insufficient sampling of the ice‐sheet bed and poor definition of subglacial basin structure and stratigraphy. Translating the knowledge of sedimentary basin processes into ice‐sheet modelling studies is critical to underpin better capacity to predict future change.

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Ice mass loss sensitivity to the Antarctic ice sheet basal thermal state

Cited by 15 publications

References 66 publications

Heterogeneous Basal Thermal Conditions Underpinning the Adélie‐George V Coast, East Antarctica

Heterogeneous Basal Thermal Conditions Underpinning the Adélie‐George V Coast, East Antarctica

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Antarctic Sedimentary Basins and Their Influence on Ice‐Sheet Dynamics

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