Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica

Wåhlin, Anna; Graham, Alastair G C; Hogan, Kelly; Queste, Bastien Y.; Boehme, Lars; Larter, Robert D; Pettit, E. C.; Wellner, Julia S.; Heywood, Karen J.

doi:10.1126/sciadv.abd7254

Cited by 56 publications

(72 citation statements)

References 41 publications

(49 reference statements)

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“…Our results are impacted by several limitations. High-resolution data, including the deep channels and other topographic features at the ice shelf base, are critical to capture detailed water pathways, sub-ice shelf circulation, and melt pattern (Adusumilli et al, 2020;Dutrieux et al, 2013;Nakayama et al, 2018;Shean et al, 2019;Wåhlin et al, 2021). Another limitation is the lack of feedback between ice melt from ocean heat flux and ice shelf draft elevation.…”

Section: Satellitementioning

confidence: 99%

Impact of Subglacial Freshwater Discharge on Pine Island Ice Shelf

Nakayama

Cai

Seroussi

2021

Geophysical Research Letters

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These changes were triggered by increasing amounts of sub-ice shelf melt under Pine Island ice shelf (PIIS), caused by intrusions of warm modified Circumpolar Deep Water (mCDW, about 3 E C warmer than the in situ freezing point) that is transported onto the continental shelf through submarine glacial troughs (Dutrieux et al., 2014;Jacobs et al., 2011;Nakayama et al., 2013;Pritchard et al., 2012). Satellite-based estimates of ice shelf melt rate close to the grounding line of Pine Island reach E 200 m 1 yr E  locally (Shean et al., 2019) and the rapid melting close to the grounding line impacts its grounding line evolution as well as its future contribution to sea-level rise (

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Section: Satellitementioning

confidence: 99%

Impact of Subglacial Freshwater Discharge on Pine Island Ice Shelf

Nakayama

Cai

Seroussi

2021

Geophysical Research Letters

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“…The two yellow stars in panel (b) mark the locations of GPS and barometric pressure records used for tidal analysis (AMIGOS stations). The red and blue arrows in panel (c) indicate the pathways of warm Circumpolar Deep Water and cold ice-shelf meltwater (Wåhlin et al, 2021). Coordinates in an Antarctic polar stereographic projection (EPSG:3031).…”

Section: Introductionmentioning

confidence: 99%

Weakening of the pinning point buttressing Thwaites Glacier, West Antarctica

et al. 2022

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Abstract. The Thwaites Eastern Ice Shelf buttresses a significant portion of Thwaites Glacier through contact with a pinning point 40 km offshore of the present grounding line. Predicting future rates of Thwaites Glacier’s contribution to sea-level rise depends on the evolution of this pinning point and the resultant change in the ice-shelf stress field since the breakup of the Thwaites Western Glacier Tongue in 2009. Here we use Landsat-8 feature tracking of ice velocity in combination with ice-sheet model perturbation experiments to show how past changes in flow velocity have been governed in large part by changes in lateral shear and pinning point interactions with the Thwaites Western Glacier Tongue. We then use recent satellite altimetry data from ICESat-2 to show that Thwaites Glacier’s grounding line has continued to retreat rapidly; in particular, the grounded area of the pinning point is greatly reduced from earlier mappings in 2014, and grounded ice elevations are continuing to decrease. This loss has created two pinned areas with ice flow now funneled between them. If current rates of surface lowering persist, the Thwaites Eastern Ice Shelf will unpin from the seafloor in less than a decade, despite our finding from airborne radar data that the seafloor underneath the pinning point is about 200 m shallower than previously reported. Advection of relatively thin and mechanically damaged ice onto the remaining portions of the pinning point and feedback mechanisms involving basal melting may further accelerate the unpinning. As a result, ice discharge will likely increase up to 10 % along a 45 km stretch of the grounding line that is currently buttressed by the Thwaites Eastern Ice Shelf.

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“…This substantial reduction in WSIE and seasonal sea-ice cover would have reduced brine rejection and likely decreased the rates of deepwater and bottom-water formation in the Weddell Sea, causing a warming of the abyssal waters (Bouttes et al, 2010;Marzocchi and Jansen, 2019). Deepwater warming would have promoted the basal melting and retreat of Weddell Sea ice shelves and marine-terminating ice streams and caused substantial Antarctic ice-sheet mass loss (Hellmer et al, 2012;Rignot et al, 2019;Wahlin et al, 2021). We hypothesize that substantial mass loss from the Weddell Sea sector of the WAIS (Turney et al, 2020) drove the Atlantic sector WSI resurgence at ∼ 126 ± 2.6 ka, as suggested by the model experiments of Menviel et al (2010), and contributed to the global sea-level rise at this time (Kopp et al, 2013;Sime et al, 2019).…”

Section: Wider Implicationsmentioning

confidence: 99%

Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e

et al. 2022

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Abstract. Environmental conditions during Marine Isotope Stage (MIS) 5e (130–116 ka) represent an important “process analogue” for understanding the climatic responses to present and future anthropogenic warming. The response of Antarctic sea ice to global warming is particularly uncertain due to the short length of the observational record. Reconstructing Antarctic winter sea-ice extent during MIS 5e therefore provides insights into the temporal and spatial patterns of sea-ice change under a warmer-than-present climate. This study presents new MIS 5e records from nine marine sediment cores located south of the Antarctic Polar Front between 55 and 70∘ S. Winter sea-ice extent and sea-surface temperatures are reconstructed using marine diatom assemblages and a modern analogue technique transfer function, and changes in these environmental variables between the three Southern Ocean sectors are investigated. The Atlantic and East Indian sector records show much more variable MIS 5e winter sea-ice extent and sea-surface temperatures than the Pacific sector records. High variability in the Atlantic sector winter sea-ice extent is attributed to high glacial meltwater flux in the Weddell Sea, indicated by increased abundances of the diatom species Eucampia antarctica and Fragilariopsis cylindrus. The high variability in the East Indian sector winter sea-ice extent is conversely believed to result from large latitudinal migrations of the flow bands of the Antarctic Circumpolar Current, inferred from latitudinal shifts in the sea-surface temperature isotherms. Overall, these findings suggest that Pacific sector winter sea ice displays a low sensitivity to warmer climates. The different variability and sensitivity of Antarctic winter sea-ice extent in the three Southern Ocean sectors during MIS 5e may have significant implications for the Southern Hemisphere climatic system under future warming.

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Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica

Cited by 56 publications

References 41 publications

Impact of Subglacial Freshwater Discharge on Pine Island Ice Shelf

Impact of Subglacial Freshwater Discharge on Pine Island Ice Shelf

Weakening of the pinning point buttressing Thwaites Glacier, West Antarctica

Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e

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