Impact of Subglacial Freshwater Discharge on Pine Island Ice Shelf

Nakayama, Yoshihiro; Cai, Chuangjian; Seroussi, Hélène

doi:10.1029/2021gl093923

Cited by 50 publications

(56 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While the source is presumed to be sub-ice shelf and/or grounding-zone ice melt, the sedimentary evidence of meltwater-derived deposition in cores KC04 and KC08 suggests subglacial drainage is an important contributor to this freshwater signal. Conversely, the substantial inflow of warm water to the east of H2 (Figure 1B; Wåhlin et al, 2021) supports the likelihood of enhanced turbulent mixing with fresh meltwater outflow along the grounding zone of western Thwaites Glacier, as is recently suggested for neighboring Pine Island Glacier (Nakayama et al, 2021). Numerical modelling of channelized drainage pathways beneath Thwaites Glacier predicts persistent drainage that discharges beneath the TGT (Hager et al, 2021).…”

Section: Connection Of Meltwater Plumes To the Contemporary Ice-ocean...supporting

confidence: 73%

“…Subglacial meltwater expulsion into the ocean and subsequent buoyancy-driven turbulence is linked to both enhanced ice melt at or near the grounding zone (Gourmelen et al, 2017;Wei et al, 2020;Nakayama et al, 2021) and ice-shelf basal channel formation (Le Brocq et al, 2013;Marsh et al, 2016). The seaward extension of subglacial channels carved upward into the ice-shelf base encourages concentrated melt by warm marine waters (e.g., Alley et al, 2016) and may lead to ice-shelf fracture (Vaughan et al, 2012;Alley et al, 2016;Dow et al, 2018) and ultimately collapse (Borstad et al, 2012;Borstad et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica

et al. 2022

View full text Add to dashboard Cite

Subglacial meltwater drainage can enhance localized melting along grounding zones and beneath the ice shelves of marine-terminating glaciers. Efforts to constrain the evolution of subglacial hydrology and the resulting influence on ice stability in space and on decadal to millennial timescales are lacking. Here, we apply sedimentological, geochemical, and statistical methods to analyze sediment cores recovered offshore Thwaites Glacier, West Antarctica to reconstruct meltwater drainage activity through the pre-satellite era. We find evidence for a long-lived subglacial hydrologic system beneath Thwaites Glacier and indications that meltwater plumes are the primary mechanism of sedimentation seaward of the glacier today. Detailed core stratigraphy revealed through computed tomography scanning captures variability in drainage styles and suggests greater magnitudes of sediment-laden meltwater have been delivered to the ocean in recent centuries compared to the past several thousand years. Fundamental similarities between meltwater plume deposits offshore Thwaites Glacier and those described in association with other Antarctic glacial systems imply widespread and similar subglacial hydrologic processes that occur independently of subglacial geology. In the context of Holocene changes to the Thwaites Glacier margin, it is likely that subglacial drainage enhanced submarine melt along the grounding zone and amplified ice-shelf melt driven by oceanic processes, consistent with observations of other West Antarctic glaciers today. This study highlights the necessity of accounting for the influence of subglacial hydrology on grounding-zone and ice-shelf melt in projections of future behavior of the Thwaites Glacier ice margin and marine-based glaciers around the Antarctic continent.

show abstract

Section: Connection Of Meltwater Plumes To the Contemporary Ice-ocean...supporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Melting rates in the grounding zone (the region immediately seaward of the grounding line where tides drive intermittent grounding and ungrounding of the ice shelf) are estimated to be 10–20 m a −1 (Brancato et al., 2020), a rate that could be supported by the observed ocean thermal forcing. Very high melt rates near the grounding line of the Pine Island Glacier have recently been attributed to subglacial freshwater discharge, but the influence on melt rates was found to be limited to the immediate vicinity of the grounding line (Nakayama et al., 2021). A similar situation may hold for the Denman, with subglacial freshwater discharge contributing to high melt rates at the grounding line and ocean thermal forcing driving lower, but more widespread, basal melt.…”

Section: Discussionmentioning

confidence: 99%

Vulnerability of Denman Glacier to Ocean Heat Flux Revealed by Profiling Float Observations

Wijk

Rintoul

Wallace

et al. 2022

Geophysical Research Letters

View full text Add to dashboard Cite

Denman Glacier, which drains a marine‐based sector of the East Antarctic Ice Sheet with an ice volume equivalent to 1.5 m of global sea level rise, has accelerated and undergone grounding line retreat in recent decades. A deep trough and retrograde bed slope inward of the grounding line leave this glacier prone to marine ice sheet instability. The ocean heat flux to the ice shelf cavity is a critical factor determining the susceptibility of the glacier to unstable retreat. Profiling float observations show modified Circumpolar Deep Water as warm as −0.16°C reaches a deep trough extending beneath the Denman Ice Tongue. The ocean heat transport (0.77 ± 0.35 TW) is sufficient to drive high rates of basal melt (70.8 ± 31.5 Gt y−1), consistent with rates inferred from glaciological observations. These results suggest the Denman Glacier is potentially at risk of unstable retreat triggered by transport of warm water to the ice shelf cavity.

show abstract

“…Inaccuracies in a parametrization based on the approximation derived here might also arise from our neglect of frazil ice dynamics, which can significantly alter the behaviour of subglacial plumes in regions where the melt rate is negative [43]. Furthermore, we have neglected subglacial discharge; although subglacial discharge is expected to have a negligible influence on the plume dynamics on the lengthscale of the entire ice shelf, there is evidence that it is responsible for the high melt rates close to the grounding line of Pine Island Glacier [51]. This is especially pertinent because enhanced melt rates close to the grounding line may disproportionately impact the dynamics of the ice sheet [7,52].…”

Section: Discussionmentioning

confidence: 99%

Asymptotic analysis of subglacial plumes in stratified environments

et al. 2022

View full text Add to dashboard Cite

Accurate predictions of basal melt rates on ice shelves are necessary for precise projections of the future behaviour of ice sheets. The computational expense associated with completely resolving the cavity circulation using an ocean model makes this approach unfeasible for multi-century simulations, and parametrizations of melt rates are required. At present, some of the most advanced melt rate parametrizations are based on a one-dimensional approximation to the melt rate that emerges from the theory of subglacial plumes applied to ice shelves with constant basal slopes and uniform ambient ocean conditions; in this work, we present an asymptotic analysis of the corresponding equations in which non-constant basal slopes and typical ambient conditions are imposed. This analysis exploits the small aspect ratio of ice shelf bases, the relatively weak thermal driving and the relative slenderness of the region separating warm, salty water at depth and cold, fresh water at the surface in the ambient ocean. We construct an approximation to the melt rate that is based on this analysis, which shows good agreement with numerical solutions in a wide variety of cases, suggesting a path towards improved predictions of basal melt rates in ice-sheet models.

show abstract

Impact of Subglacial Freshwater Discharge on Pine Island Ice Shelf

Cited by 50 publications

References 70 publications

Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica

Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica

Vulnerability of Denman Glacier to Ocean Heat Flux Revealed by Profiling Float Observations

Asymptotic analysis of subglacial plumes in stratified environments

Contact Info

Product

Resources

About