Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet

Morlighem, Mathieu; Rignot, Eric; Binder, Tobias; Blankenship, D. D.; Drews, Reinhard; Eagles, Graeme; Eisen, Olaf; Ferraccioli, Fausto; Forsberg, R.; Fretwell, Peter T.; Goel, Vikram; Greenbaum, J. S.; Gudmundsson, G. Hilmar; Guo, Jingxue; Helm, Veit; Hofstede, Coen; Howat, I. M.; Humbert, Angelika; Jokat, Wilfried; Karlsson, Nanna B.; Lee, Won Sang; Matsuoka, Kenichi; Millan, Romain; Mouginot, J.; Paden, John; Pattyn, Frank; Roberts, JL; Rosier, Sebastian; Ruppel, Antonia; Seroussi, H. L.; Smith, Emma C.; Steinhage, Daniel; Sun, Bо; Broeke, Michiel Rvan Den M.R.v.d.; Ommen, Tas Dvan T.D.v.; Wessem, Jan Melchior van; Young, Duncan

doi:10.1038/s41561-019-0510-8

Cited by 696 publications

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“…They indicate a variation of 6.8% of the total ice mass among the simulations, between 2.31 and 2.49 × 10 7 Gt, and a variation of 7.7% in the total ice mass above floatation, between 1.99 and 2.15 × 10 7 Gt or between 55.0 and 59.4 m of SLE, when the latest estimate is 57.9 ± 0.9 m (Morlighem et al, 2019a). Figure 3 shows the root mean square error (RMSE) between modeled 285 and observed thickness and velocity at the beginning of the experiments.…”

mentioning

confidence: 88%

“…The JPL_ISSM ice sheet model configuration relies on data assimilation of present-day conditions, followed by a short model relaxation as described in Schlegel et al (2018). The model domain covers present-day Antarctic Ice Sheet, and its geometry is based on an early version of BedMachine Antarctica (Morlighem et al, 2019a). The model is based on the 2D Shelfy-…”

Section: Jpl_issmmentioning

confidence: 99%

“…We use an identical approach to the one described in Golledge et al (2019). Starting from initial bedrock and ice thickness 760 conditions from Morlighem et al (2019a), together with reference climatology from van Wessem et al (2014) we run a multistage spinup that guarantees well-evolved thermal and dynamic conditions without loss of accuracy in terms of geometry. This is achieved through an iterative nudging procedure, in which incremental grid refinement steps are employed that also include resetting of ice thicknesses to initial values.…”

Section: Vuw_pismmentioning

confidence: 99%

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ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

Seroussi¹,

Goelzer²,

Morlighem³

2020

Preprint

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122

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Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and inform on the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimated the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes and the forcings employed. This study presents results from 18 simulations from 15 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015-2100, forced with different scenarios from the Cou-5 pled Model Intercomparison Project Phase 5 (CMIP5) representative of the spread in climate model results. The contribution of the Antarctic ice sheet in response to increased warming during this period varies between -7.8 and 30.0 cm of Sea Level Equivalent (SLE). The evolution of the West Antarctic Ice Sheet varies widely among models, with an overall mass loss up to 21.0 cm SLE in response to changes in oceanic conditions. East Antarctica mass change varies between -6.5 and 16.5 cm SLE, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario 10 forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional mass loss of 8 mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 AOGCMs show an overall mass loss of 10 mm SLE compared to simulations done under present-day 15 conditions, with limited mass gain in East Antarctica.

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mentioning

confidence: 88%

Section: Jpl_issmmentioning

confidence: 99%

Section: Vuw_pismmentioning

confidence: 99%

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ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

Seroussi¹,

Goelzer²,

Morlighem³

2020

Preprint

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122

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“…EWM: Ellsworth-Whitmore Mountain (in red, polygon from Jordan et al (2013)); ESH: Ellsworth Subglacial Highlands (in black). In the background is Bedmachine elevation model (500 m) (Morlighem et al, 2019), with contour lines every 500 m. Projection: Antarctic Polar Stereographic (EPSG 3031).…”

Section: Introductionmentioning

confidence: 99%

Subglacial lakes and hydrology across the Ellsworth Subglacial Highlands, West Antarctica

Napoleoni¹,

Jamieson²,

Ross³

et al. 2020

Preprint

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Abstract. Subglacial water plays an important role in ice sheet dynamics and stability. It is often located at the onset of ice streams and has the potential to enhance ice flow downstream by lubricating the ice-bed interface. The most recent subglacial lake inventory of Antarctica mapped nearly 400 lakes, of which ~ 14 % are found in West Antarctica. Despite the potential importance of subglacial water for ice dynamics, there is a lack of detailed subglacial water characterization in West Antarctica. Using radio-echo sounding data, we analyse the ice-bed interface to detect subglacial lakes. We report 37 previously uncharted subglacial lakes and present a systematic analysis of their physical properties. This represents a ~ 60 % increase in subglacial lakes in the region. Additionally, a new digital elevation model of basal topography was built and used to create a detailed hydropotential model of Ellsworth Subglacial Highlands to simulate the subglacial hydrological network. This approach allows us to characterize basal hydrology, subglacial water catchments and connections between them. Furthermore, the simulated subglacial hydrological catchments of Rutford Ice Stream, Pine Island Glacier and Thwaites Glacier do not match precisely with their ice surface catchments.

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“…Recent studies have highlighted a lack of sub‐ice‐shelf bathymetry as a “major limitation” (Pattyn et al, 2017) for future projections of Antarctic mass balance. Improved bathymetric mapping allows determination of water access pathways and calculation of spatially and temporally variable melt rates (e.g., Cochran et al, 2014; Goldberg et al, 2019; Milillo et al, 2019; Morlighem et al, 2020; Pattyn et al, 2017; Tinto et al, 2019). In addition, sub‐ice‐shelf bathymetry also provides information about ice dynamic history.…”

Section: Introductionmentioning

confidence: 99%

Detailed Seismic Bathymetry Beneath Ekström Ice Shelf, Antarctica: Implications for Glacial History and Ice‐Ocean Interaction

Smith

Hattermann

Kuhn

et al. 2020

Geophysical Research Letters

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The shape of ice shelf cavities are a major source of uncertainty in understanding ice-ocean interactions. This limits assessments of the response of the Antarctic ice sheets to climate change. Here we use vibroseis seismic reflection surveys to map the bathymetry beneath the Ekström Ice Shelf, Dronning Maud Land. The new bathymetry reveals an inland-sloping trough, reaching depths of 1,100 m below sea level, near the current grounding line, which we attribute to erosion by palaeo-ice streams. The trough does not cross-cut the outer parts of the continental shelf. Conductivity-temperature-depth profiles within the ice shelf cavity reveal the presence of cold water at shallower depths and tidal mixing at the ice shelf margins. It is unknown if warm water can access the trough. The new bathymetry is thought to be representative of many ice shelves in Dronning Maud Land, which together regulate the ice loss from a substantial area of East Antarctica.Plain Language Summary Antarctica is surrounded by floating ice shelves, which play a crucial role in regulating the flow of ice from the continent into the oceans. The ice shelves are susceptible to melting from warm ocean waters beneath them. In order to better understand the melting, knowledge of the shape and depth of the ocean cavity beneath ice shelves is crucial. In this study, we present new measurements of the sea floor depth beneath Ekström Ice Shelf in East Antarctica. The measurements reveal a much deeper sea floor than previously known. We discuss the implications of this for access of warm ocean waters, which can melt the base of the ice shelf and discuss how the observed sea floor features were formed by historical ice flow regimes. Although Ekström Ice Shelf is relatively small, the geometry described here is thought to be representative of the topography beneath many ice shelves in this region, which together regulate the ice loss from a substantial area of East Antarctica.

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Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet

Cited by 696 publications

References 33 publications

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

Subglacial lakes and hydrology across the Ellsworth Subglacial Highlands, West Antarctica

Detailed Seismic Bathymetry Beneath Ekström Ice Shelf, Antarctica: Implications for Glacial History and Ice‐Ocean Interaction

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