Recent Dramatic Thinning of Largest West Antarctic Ice Stream Triggered by Oceans

Payne, Antony J.; Vieli, Andreas; Shepherd, Andrew; Rignot, Eric

doi:10.1002/9781118782033.ch13

Cited by 70 publications

(103 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The recently inferred destabilization of the Amundsen Sea sector coincides with an increase in the volume and temperature of relatively warm circumpolar deep water that reaches into the ice-shelf cavities in the Amundsen Sea (15,16). The resulting substantially enhanced sub-ice-shelf melting facilitated the retreat of the grounding line of several tributaries onto the potentially unstable down-sloping bed section.…”

mentioning

confidence: 99%

Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin

Feldmann

Levermann

2015

Proc. Natl. Acad. Sci. U.S.A.

186

152

View full text Add to dashboard Cite

The future evolution of the Antarctic Ice Sheet represents the largest uncertainty in sea-level projections of this and upcoming centuries. Recently, satellite observations and high-resolution simulations have suggested the initiation of an ice-sheet instability in the Amundsen Sea sector of West Antarctica, caused by the last decades' enhanced basal ice-shelf melting. Whether this localized destabilization will yield a full discharge of marine ice from West Antarctica, associated with a global sea-level rise of more than 3 m, or whether the ice loss is limited by ice dynamics and topographic features, is unclear. Here we show that in the Parallel Ice Sheet Model, a local destabilization causes a complete disintegration of the marine ice in West Antarctica. In our simulations, at 5-km horizontal resolution, the region disequilibrates after 60 y of currently observed melt rates. Thereafter, the marine ice-sheet instability fully unfolds and is not halted by topographic features. In fact, the ice loss in Amundsen Sea sector shifts the catchment's ice divide toward the Filchner-Ronne and Ross ice shelves, which initiates grounding-line retreat there. Our simulations suggest that if a destabilization of Amundsen Sea sector has indeed been initiated, Antarctica will irrevocably contribute at least 3 m to global sea-level rise during the coming centuries to millennia.West Antarctic Ice Sheet | sea-level rise | tipping point | instability | marine ice-sheet instability T he Antarctic Ice Sheet is losing mass at an accelerating rate, and thus increasingly contributes to global sea-level rise (1,2). To what extent this is caused by anthropogenic warming of the atmosphere is unclear. The Amundsen Sea sector of West Antarctica accounts for the largest part of the ice loss, manifesting in a speed-up, thinning, and retreat of tributaries such as Pine Island Glacier and Thwaites Glacier during the last 4 decades (3-5). Large portions of the West Antarctic Ice Sheet (WAIS) are grounded on bedrock below sea level (6, 7). These so-called marine parts of the ice sheet hold an ice volume that would elevate global mean sea level by about 3.3 m (8). The bed below this marine ice is generally down-sloping in the inland direction. A grounding line (the line that separates the grounded ice sheet from the floating ice shelf) that is located on such bed has been shown to be potentially unstable (9, 10). The associated marine ice-sheet instability (i.e., self-sustained ice-sheet retreat) can be hindered by the buttressing of ice shelves, which has been investigated in different modeling frameworks (11)(12)(13)(14).The recently inferred destabilization of the Amundsen Sea sector coincides with an increase in the volume and temperature of relatively warm circumpolar deep water that reaches into the ice-shelf cavities in the Amundsen Sea (15, 16). The resulting substantially enhanced sub-ice-shelf melting facilitated the retreat of the grounding line of several tributaries onto the potentially unstable down-sloping bed section. Complex, high...

show abstract

mentioning

confidence: 99%

Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin

Feldmann

Levermann

2015

Proc. Natl. Acad. Sci. U.S.A.

186

152

View full text Add to dashboard Cite

show abstract

“…Results of computer simulations are equivocal; the pattern of ice thinning and acceleration at the PIG is reproduced through modest reductions in basal shear stress inland or the reduction in lateral and basal stress resulting from thinning and grounding line retreat Payne et al, 2004]. For PIG, at least, models of this scenario appear to explain the satellite observations effectively, but ice discharge from the TG increased only moderately over the same period through widening of its fast flowing section , and so the nature of the grounded AS mass instability remains uncertain.…”

mentioning

confidence: 99%

“…Thinning reduces lateral traction, and, through grounding line retreat, basal traction. Computer simulations Payne et al, 2004] predict that these events lead to accelerated ice flow and thinning directly upstream, which can then diffuse rapidly further inland Payne et al, submitted manuscript, 2004]. To the extent these models reproduce the actual dynamics of AS outlet glaciers, enhanced ocean melting explains their synchronised imbalance [Shepherd et al, 2002].…”

mentioning

confidence: 99%

“…[3] Speculation as to the source of the AS sector imbalance has considered the effects of both internal and external disturbances Thomas and Rignot, 2004;Payne et al, 2004]. Results of computer simulations are equivocal; the pattern of ice thinning and acceleration at the PIG is reproduced through modest reductions in basal shear stress inland or the reduction in lateral and basal stress resulting from thinning and grounding line retreat Payne et al, 2004].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Warm Ocean is Eroding West Antarctic Ice Sheet

Shepherd¹,

Rignot²

2009

Collected Reprint Series

Self Cite

119

146

View full text Add to dashboard Cite

[1] Satellite radar measurements show that ice shelves in Pine Island Bay have thinned by up to 5.5 m yr À1 over the past decade. The pattern of shelf thinning mirrors that of their grounded tributaries -the Pine Island, Thwaites and Smith glaciers -and ocean currents on average 0.5°C warmer than freezing appear to be the source. The synchronised imbalance of the inland glaciers is the result of reduced lateral and basal tractions at their termini, and the drawdown of grounded ice shows that Antarctica is more sensitive to changing climates than was previously considered.

show abstract

“…propagate inland on decadal timescales [Payne et al, 2004]. These fluctuations in CDW 531 input are in turn driven by decadal variability in large-scale atmospheric circulation (e.g., 532…”

Section: Island Glacier Ice Shelf Is Determined By the Properties Andmentioning

confidence: 99%

Amundsen Sea sea-ice variability, atmospheric circulation, and spatial variations in snow isotopic composition from new West Antarctic firn cores

Criscitiello¹

2014

View full text Add to dashboard Cite

Recent work has documented dramatic changes in the West Antarctic Ice Sheet (WAIS) over the past 30 years (e.g., mass loss, glacier acceleration, surface warming) due largely to the influence of the marine environment. WAIS is particularly vulnerable to largescale atmospheric dynamics that remotely influence the transport of marine aerosols to the ice sheet. Understanding seasonal-to decadal-scale changes in the marine influence on WAIS (particularly sea-ice concentration) is vital to our ability to predict future change. In this thesis, I develop tools that enable us to reconstruct the source and transport variability of marine aerosols to West Antarctica in the past. I validate new firn-core sea-ice proxies over the satellite era; results indicate that firn-core glaciochemical records from this dynamic region may provide a proxy for reconstructing Amundsen Sea and Pine Island Bay polynya variability prior to the satellite era. I next investigate the remote influence of tropical Pacific variability on marine aerosol transport to West Antarctica. Results illustrate that both source and transport of marine aerosols to West Antarctica are controlled by remote atmospheric forcing, linking local dynamics (e.g., katabatic winds) with large-scale teleconnections to the tropics (e.g., Rossby waves). Oxygen isotope records allow me to further investigate the relationship between West Antarctic firn-core records and temperature, precipitation origin, sea-ice variability, and large-scale atmospheric circulation. I show that the tropical Pacific remotely influences the source and transport of the isotopic signal to the coastal ice sheet. The regional firn-core array reveals a spatially varying response to remote tropical Pacific forcing. Finally, I investigate longer-term (~200 year) ocean and ice-sheet changes using the methods and results gleaned from the previous work. I utilize sea-ice proxies to reconstruct long-term changes in sea-ice and polynya variability in the Amundsen Sea, and show that the tropics remotely influence West Antarctica over decadal timescales. This thesis utilizes some of the highest-resolution, most coastal records in the region to date, and provides some of the first analyses of the seasonal-to decadal-scale controls on source and transport of marine aerosols to West Antarctica. , 1975]. The instability of WAIS is largely a consequence of its bedrock, which lies below sea level and slopes downward from the margins of the ice sheet to its interior. Removal of the fringing ice shelves may result in the rapid and irreversible inland migration of the grounding line [Thomas et al., 1979].While collapse is a low-probability, high-impact event, its potential contribution to sealevel rise (SLR) combined with recent changes in mass balance and outlet glacier velocities highlight the importance of focusing efforts on better understanding the dynamics in this key region. Pine Island and Thwaites Glaciers are two of the largest Antarctic contributors to recent SLR [Rignot et al., 2008; Shepherd et ...

show abstract

Recent Dramatic Thinning of Largest West Antarctic Ice Stream Triggered by Oceans

Cited by 70 publications

References 18 publications

Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin

Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin

Warm Ocean is Eroding West Antarctic Ice Sheet

Amundsen Sea sea-ice variability, atmospheric circulation, and spatial variations in snow isotopic composition from new West Antarctic firn cores

Contact Info

Product

Resources

About