Glacier Surge After Ice Shelf Collapse

Angelis, Hernán De; Skvarca, Pedro

doi:10.1126/science.1077987

Cited by 373 publications

(241 citation statements)

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“…Faster than previously anticipated, ice streams feeding the ice shelves respond to changes in the ice shelf geometry (De Angelis and Skvarca 2003), thus increasing the mass loss of the Antarctic ice sheet and contributing to sea level rise. Satellite observations reveal that various ice streams of the West Antarctic Ice Sheet (WAIS) are thinning (Wingham et al 2006) and accelerating (Rignot 2008).…”

Section: Introductionmentioning

confidence: 99%

A box model of circulation and melting in ice shelf caverns

Olbers

Hellmer

2009

Ocean Dynamics

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A simple box model of the circulation into and inside the ocean cavern beneath an ice shelf is used to estimate the melt rates of Antarctic glaciers and ice shelves. The model uses simplified cavern geometries and includes a coarse parameterization of the overturning circulation and vertical mixing. The melting/freezing physics at the ice shelf/ocean interface are those usually implemented in high resolution circulation models of ice shelf caverns. The model is driven by the thermohaline inflow conditions and coupling to the heat and freshwater exchanges at the sea surface in front of the cavern. We tune the model for Pine Island Glacier and then apply it to six other major caverns. The dependence of the melting rate on thermohaline conditions at the ice shelf front is investigated for this set of caverns, including sensitivity studies, alternative parameterizations, and warming scenarios. An analytical relation between the melting rate and the inflow temperature is derived for a particular model version, showing a quadratic dependence of basal melting on a small temperature difference between the inflow and the grounding zone which changes to a linear dependence for larger differences.The model predicts melting at all ice shelf bases in agreement with observations, ranging from below a meter per year for Ronne Ice Shelf to about 25 m/y for the Pine Island Glacier. In a warming scenario with a one degree increase of the inflow temperature the latter glacier responds with a 1.4 fold increase of the melting rate. Other caverns respond by more than a ten fold increase, as e.g. Ronne Ice Shelf. The model is suitable for use as simple fast module in coarse large-scale ocean models.

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Section: Introductionmentioning

confidence: 99%

A box model of circulation and melting in ice shelf caverns

Olbers

Hellmer

2009

Ocean Dynamics

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“…The loss of ice shelves on the Antarctic Peninsula has been followed by many-fold increases in the velocity of the glaciers that fed them (Rott et al, 2002;Rignot et al, 2004a;Scambos et al, 2004) and in considerable thinning of these glaciers (De Angelis and Skvarca, 2003;Scambos et al, 2004). Given the very different geometry (seaward-sloping bed) of these glaciers compared to WAIS ice streams, it is arguable how relevant these results are, but similar acceleration and thinning of Jacobshavns Isbrae in Greenland in response to shrinkage of its floating tongue (Thomas, 2004) undoubtedly add to our confidence that the removal of ice shelves will cause glacierflow to accelerate.…”

Section: Bindschadler Et Al (2002) Went Back To the Few Useful Visibmentioning

confidence: 99%

West Antarctic Ice Sheet collapse – the fall and rise of a paradigm

Vaughan

2008

Climatic Change

115

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It is now almost 30 years since John Mercer (1978) first presented the idea that climate change could eventually cause a rapid deglaciation, or "collapse", of a large part of the West Antarctic ice sheet (WAIS), raising world sea levels by 5 metres and causing untold economic and social impacts. This idea, apparently simple and scientifically plausible, created a vision of the future, sufficiently alarming that it became a paradigm for a generation of researchers and provided an icon for the green movement. Through the 1990s, however, a lack of observational evidence for ongoing retreat in WAIS and improved understanding of the complex dynamics of ice streams meant that estimates of likelihood of collapse seemed to be diminishing. In the last few years, however, satellite studies over the apparently inaccessible Amundsen Sea sector of West Antarctica have shown clear evidence of ice sheet retreat showing all the features that might have been predicted for emergent collapse. These studies are re-invigorating the paradigm, albeit in a modified form, and debate about the future stability of WAIS. Since much of WAIS appears to be stable, it may, no longer be reasonable to suggest there is an imminent threat of a 5-m rise in sea level resulting from complete collapse of the West Antarctic ice sheet, but there is strong evidence that the Amundsen Sea embayment is changing rapidly. This area alone, contains the potential to raise sea level by around ~1.5 m, but more importantly it seems likely that it could, alter rapidly enough, to make a significant addition to the rate of sea-level rise over coming two centuries. Furthermore, a plausible connection between contemporary climate change and the fate of the ice sheet appears to be developing. The return of the paradigm presents a dilemma for policy-makers, and establishes a renewed set of priorities for the glaciological community. In particular, we must establish whether the hypothesized instability in WAIS is real, or simply an oversimplification resulting from inadequate understanding of the feedbacks that allow ice sheets to achieve equilibrium: and whether there is any likelihood that contemporary climate change could initiate collapse.

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“…Ocean currents on average 0.5°C warmer than freezing appear to have precipitated a sizable drawdown of ice from the WAIS interior. Elsewhere, ice shelf erosion and disintegration have preceded increased discharge from glaciers upstream [De Angelis and Skvarca, 2003]. The consequences of a warming ocean on the grounded Antarctic ice mass needs more attention than it has received to date [Warwick et al, 1996].…”

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confidence: 99%

Warm Ocean is Eroding West Antarctic Ice Sheet

Shepherd¹,

Rignot²

2009

Collected Reprint Series

119

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[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.

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Glacier Surge After Ice Shelf Collapse

Cited by 373 publications

References 16 publications

A box model of circulation and melting in ice shelf caverns

A box model of circulation and melting in ice shelf caverns

West Antarctic Ice Sheet collapse – the fall and rise of a paradigm

Warm Ocean is Eroding West Antarctic Ice Sheet

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