Sensitivity of the dynamics of Pine Island Glacier, West Antarctica, to climate forcing for the next 50 years

Abstract. Pine Island Glacier, a major contributor to sea level rise in West Antarctica, has been undergoing significant changes over the last few decades. Here, we employ a three-dimensional, higher-order model to simulate its evolution over the next 50 yr in response to changes in its surface mass balance, the position of its calving front and ocean-induced ice shelf melting. Simulations show that the largest climatic impact on ice dynamics is the rate of ice shelf melting, which rapidly affects the glacier speed over several hundreds of kilometers upstream of the grounding line. Our simulations show that the speedup observed in the 1990s and 2000s is consistent with an increase in sub-ice-shelf melting. According to our modeling results, even if the grounding line stabilizes for a few decades, we find that the glacier reaction can continue for several decades longer. Furthermore, Pine Island Glacier will continue to change rapidly over the coming decades and remain a major contributor to sea level rise, even if ocean-induced melting is reduced.

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Sensitivity of the dynamics of Pine Island Glacier, West Antarctica, to climate forcing for the next 50 years

The Cryosphere Discussions ◽

10.5194/tcd-8-1873-2014 ◽

2014 ◽

Vol 8 (2) ◽

pp. 1873-1894 ◽

Cited By ~ 3

Author(s):

H. Seroussi ◽

M. Morlighem ◽

E. Rignot ◽

J. Mouginot ◽

E. Larour ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Three Dimensional ◽

Climate Forcing ◽

Major Contributor ◽

West Antarctica ◽

Climatic Impact ◽

Ice Shelf ◽

Ice Dynamics ◽

Surface Mass

Abstract. Pine Island Glacier, a major contributor to sea level rise in West Antarctica, has been undergoing significant changes over the last few decades. Here, we employ a three-dimensional, higher-order model to simulate its evolution over the next fifty years in response to changes in its surface mass balance, the position of its calving front and ocean-induced ice shelf melting. Simulations show that the largest climatic impact on ice dynamics is the rate of ice shelf melting, which rapidly affects the glacier speed over several hundreds of kilometers upstream of the grounding line. Our simulations show that the speedup observed in the 1990s and 2000s is consistent with an increase in sub-ice-shelf melting. According to our modeling results, Pine Island Glacier will continue to change rapidly over the coming decades and remain a major contributor to sea level rise, even if ocean-induced melting is reduced.

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Stopping the Flood: Could We Use Targeted Geoengineering to Mitigate Sea Level Rise?

10.5194/tc-2018-95 ◽

2018 ◽

Cited By ~ 1

Author(s):

Michael J. Wolovick ◽

John C. Moore

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Dynamic Feedback ◽

West Antarctica ◽

Ice Shelf ◽

Long Run ◽

Grounding Line ◽

Individual Source ◽

Engineering Projects

Abstract. The Marine Ice Sheet Instability (MISI) is a dynamic feedback that can cause an ice sheet to enter a runaway collapse. Thwaites Glacier, West Antarctica, is the largest individual source of future sea level rise and may have already entered the MISI. Here, we use a suite of coupled ice–ocean flowband simulations to explore whether targeted geoengineering using an artificial sill or artificial ice rises could counter a collapse. Successful interventions occur when the floating ice shelf regrounds on the pinning points, increasing buttressing and reducing ice flux across the grounding line. Regrounding is more likely with a continuous sill that is able to block warm water transport to the grounding line. The smallest design we consider is comparable in scale to existing civil engineering projects but has only a 30 % success rate, while larger designs are more effective. There are multiple possible routes forward to improve upon the designs that we considered, and with decades or more to research designs it is plausible that the scientific community could come up with a plan that was both effective and achievable. While reducing emissions remains the short-term priority for minimizing the effects of climate change, in the long run humanity may need to develop contingency plans to deal with an ice sheet collapse.

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Simulating Antarctic subglacial hydrology processes underneath Pine Island Glacier, West Antarctica, using GlaDS model in Elmer/Ice

10.5194/egusphere-egu2020-8344 ◽

2020 ◽

Author(s):

yufang zhang ◽

John Moore ◽

Michael Wolovick ◽

Rupert Gladstone ◽

Thomas Zwinger ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Drainage System ◽

The State ◽

Effective Pressure ◽

West Antarctica ◽

Ice Dynamics ◽

Grounding Line ◽

Basal Sliding

Abstract: Very little is known about the subglacial hydrologic system under the Antarctic Ice Sheet due to the difficulty of directly observing the bottom of the ice sheet. Hydrology modeling is a powerful tool to simulate the spatial distribution of crucial hydrologic properties under the ice sheet. Here, we use the state-of-art two-dimensional Glacier Drainage System model (GlaDS) to simulate both distributed sheet flow and continuous channels under Pine Island Glacier (PIG), West Antarctica, one of the largest contributors to sea level rise in Antarctica.We adopt an unstructured triangular mesh which enables channels to form along element edges. We drive the model with meltwater computed from an inversion and steady temperature simulation of PIG using a Stokes flow ice dynamic model. Our domain comprises the full PIG catchment. We aim to study the pattern and development of water pressure, hydraulic potential, water sheet thickness and discharge, as well as channel area and flux, which together describe the state of the basal system.Our results for hydraulic potential correctly route water towards the grounding line, while we find near-zero effective pressure underneath the main trunk of PIG, consistent with the low basal drag and low driving stress there. This has implications for the representation of sliding in ice dynamic models: typical assumptions about hydrology connectivity to the ocean will overestimate effective pressure. When run forward in time, efficient channels evolve near the grounding line indicating an efficient drainage system where water fluxes are high in the downstream part of the PIG.By applying GlaDS to a real marine ice sheet catchment we can better understand how basal hydrology modulates ice dynamics through basal sliding. We plan to compare our model predictions of effective pressure and drainage system with driving stress and inversions of basal drag. This will allow us to see the relationship between basal hydrology and basal sliding under PIG, and provide us better tools to predict the evolution of the region in view of future climate scenarios. Moving forward, we plan to couple the hydrology model with the ice dynamics model to make more accurate projections of sea level rise from PIG.Key Words: West Antarctica, subglacial hydrology, drainage system, GlaDS, Elmer/Ice, Pine Island Glacier

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Stopping the flood: could we use targeted geoengineering to mitigate sea level rise?

The Cryosphere ◽

10.5194/tc-12-2955-2018 ◽

2018 ◽

Vol 12 (9) ◽

pp. 2955-2967 ◽

Cited By ~ 12

Author(s):

Michael J. Wolovick ◽

John C. Moore

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Dynamic Feedback ◽

West Antarctica ◽

Ice Shelf ◽

Long Run ◽

Grounding Line ◽

Individual Source ◽

Engineering Projects

Abstract. The Marine Ice Sheet Instability (MISI) is a dynamic feedback that can cause an ice sheet to enter a runaway collapse. Thwaites Glacier, West Antarctica, is projected to be the largest individual source of future sea level rise and may have already entered MISI. Here, we use a suite of coupled quasi-2-D ice–ocean simulations to explore whether targeted geoengineering using either a continuous artificial sill or isolated artificial pinning points could counter a collapse. Successful interventions occur when the floating ice shelf regrounds on the structure, increasing buttressing and reducing ice flux across the grounding line. Regrounding is more likely with a continuous sill that is able to block warm water transport to the grounding line. The smallest design we consider is comparable in scale to existing civil engineering projects but only has a 30 % success rate, while larger designs are more effective. There are multiple possible routes forward to improve upon the designs that we considered, and with decades or more to research designs it is plausible that the scientific community could come up with a plan that is both effective and achievable. While reducing emissions remains the short-term priority for minimizing the effects of climate change, in the long run humanity may need to develop contingency plans to deal with an ice sheet collapse.

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Damage accelerates ice shelf instability and mass loss in Amundsen Sea Embayment

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1912890117 ◽

2020 ◽

Vol 117 (40) ◽

pp. 24735-24741 ◽

Cited By ~ 1

Author(s):

Stef Lhermitte ◽

Sainan Sun ◽

Christopher Shuman ◽

Bert Wouters ◽

Frank Pattyn ◽

...

Keyword(s):

Sea Level ◽

Rapid Development ◽

Shear Zones ◽

West Antarctica ◽

Ice Shelf ◽

Damage Development ◽

Amundsen Sea ◽

Ice Shelves ◽

Grounding Line ◽

Global Sea Level

Pine Island Glacier and Thwaites Glacier in the Amundsen Sea Embayment are among the fastest changing outlet glaciers in West Antarctica with large consequences for global sea level. Yet, assessing how much and how fast both glaciers will weaken if these changes continue remains a major uncertainty as many of the processes that control their ice shelf weakening and grounding line retreat are not well understood. Here, we combine multisource satellite imagery with modeling to uncover the rapid development of damage areas in the shear zones of Pine Island and Thwaites ice shelves. These damage areas consist of highly crevassed areas and open fractures and are first signs that the shear zones of both ice shelves have structurally weakened over the past decade. Idealized model results reveal moreover that the damage initiates a feedback process where initial ice shelf weakening triggers the development of damage in their shear zones, which results in further speedup, shearing, and weakening, hence promoting additional damage development. This damage feedback potentially preconditions these ice shelves for disintegration and enhances grounding line retreat. The results of this study suggest that damage feedback processes are key to future ice shelf stability, grounding line retreat, and sea level contributions from Antarctica. Moreover, they underline the need for incorporating these feedback processes, which are currently not accounted for in most ice sheet models, to improve sea level rise projections.

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Retreat of Thwaites Glacier, West Antarctica, over the next 100 years using various ice flow models, ice shelf melt scenarios and basal friction laws

The Cryosphere ◽

10.5194/tc-12-3861-2018 ◽

2018 ◽

Vol 12 (12) ◽

pp. 3861-3876 ◽

Cited By ~ 12

Author(s):

Hongju Yu ◽

Eric Rignot ◽

Helene Seroussi ◽

Mathieu Morlighem

Keyword(s):

Sea Level ◽

Initial Conditions ◽

Numerical Models ◽

West Antarctica ◽

Ice Shelf ◽

Flow Models ◽

Friction Laws ◽

Basal Friction ◽

Grounding Line ◽

Western Side

Abstract. Thwaites Glacier (TG), West Antarctica, has experienced rapid, potentially irreversible grounding line retreat and mass loss in response to enhanced ice shelf melting. Results from recent numerical models suggest a large spread in the evolution of the glacier in the coming decades to a century. It is therefore important to investigate how different approximations of the ice stress balance, parameterizations of basal friction and ice shelf melt parameterizations may affect projections. Here, we simulate the evolution of TG using ice sheet models of varying levels of complexity, different basal friction laws and ice shelf melt to quantify their effect on the projections. We find that the grounding line retreat and its sensitivity to ice shelf melt are enhanced when a full-Stokes model is used, a Budd friction is used and ice shelf melt is applied on partially floating elements. Initial conditions also impact the model results. Yet, all simulations suggest a rapid, sustained retreat of the glacier along the same preferred pathway. The fastest retreat rate occurs on the eastern side of the glacier, and the slowest retreat occurs across a subglacial ridge on the western side. All the simulations indicate that TG will undergo an accelerated retreat once the glacier retreats past the western subglacial ridge. Combining all the simulations, we find that the uncertainty of the projections is small in the first 30 years, with a cumulative contribution to sea level rise of 5 mm, similar to the current rate. After 30 years, the contribution to sea level depends on the model configurations, with differences up to 300 % over the next 100 years, ranging from 14 to 42 mm.

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Trends and projections in ice sheet mass balance

10.5194/egusphere-egu2020-20660 ◽

2020 ◽

Author(s):

Andrew Shepherd ◽

Keyword(s):

Mass Balance ◽

Sea Level Rise ◽

Sea Level ◽

Ice Sheets ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Dynamics ◽

Surface Mass ◽

Sea Levels ◽

Global Sea Level

In recent decades, the Antarctic and Greenland Ice Sheets have been major contributors to global sea-level rise and are expected to be so in the future. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the degree and trajectory of today&#8217;s imbalance remain uncertain. Here we compare and combine 26 individual satellite records of changes in polar ice sheet volume, flow and gravitational potential to produce a reconciled estimate of their mass balance. Since the early 1990&#8217;s, ice losses from Antarctica and Greenland have caused global sea-levels to rise by 18.4 millimetres, on average, and there has been a sixfold increase in the volume of ice loss over time. Of this total, 41 % (7.6 millimetres) originates from Antarctica and 59 % (10.8 millimetres) is from Greenland. In this presentation, we compare our reconciled estimates of Antarctic and Greenland ice sheet mass change to IPCC projection of sea level rise to assess the model skill in predicting changes in ice dynamics and surface mass balance. &#160;Cumulative ice losses from both ice sheets have been close to the IPCC&#8217;s predicted rates for their high-end climate warming scenario, which forecast an additional 170 millimetres of global sea-level rise by 2100 when compared to their central estimate.

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1512482112 ◽

2015 ◽

Vol 112 (46) ◽

pp. 14191-14196 ◽

Cited By ~ 62

Author(s):

Johannes Feldmann ◽

Anders Levermann

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Horizontal Resolution ◽

West Antarctica ◽

Amundsen Sea ◽

Ice Dynamics ◽

Antarctic Ice Sheet ◽

Topographic Features ◽

Global Sea Level

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.

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Changes in ice dynamics and mass balance of the Antarctic ice sheet

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2006.1793 ◽

2006 ◽

Vol 364 (1844) ◽

pp. 1637-1655 ◽

Cited By ~ 77

Author(s):

Eric Rignot

Keyword(s):

Mass Balance ◽

Sea Level ◽

Ice Sheet ◽

East Antarctica ◽

West Antarctica ◽

Ice Shelf ◽

Ice Dynamics ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

The Antarctic

The concept that the Antarctic ice sheet changes with eternal slowness has been challenged by recent observations from satellites. Pronounced regional warming in the Antarctic Peninsula triggered ice shelf collapse, which led to a 10-fold increase in glacier flow and rapid ice sheet retreat. This chain of events illustrated the vulnerability of ice shelves to climate warming and their buffering role on the mass balance of Antarctica. In West Antarctica, the Pine Island Bay sector is draining far more ice into the ocean than is stored upstream from snow accumulation. This sector could raise sea level by 1 m and trigger widespread retreat of ice in West Antarctica. Pine Island Glacier accelerated 38% since 1975, and most of the speed up took place over the last decade. Its neighbour Thwaites Glacier is widening up and may double its width when its weakened eastern ice shelf breaks up. Widespread acceleration in this sector may be caused by glacier ungrounding from ice shelf melting by an ocean that has recently warmed by 0.3 °C. In contrast, glaciers buffered from oceanic change by large ice shelves have only small contributions to sea level. In East Antarctica, many glaciers are close to a state of mass balance, but sectors grounded well below sea level, such as Cook Ice Shelf, Ninnis/Mertz, Frost and Totten glaciers, are thinning and losing mass. Hence, East Antarctica is not immune to changes.

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Recent retreat of Greenland's marine terminating glaciers has a lasting impact on velocity and mass loss during the 21st Century

10.5194/egusphere-egu21-9908 ◽

2021 ◽

Author(s):

Isabel Nias ◽

Sophie Nowicki ◽

Denis Felikson

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Initial State ◽

Ice Dynamics ◽

Total Contribution ◽

Surface Mass ◽

Glacier Terminus

Mass loss from the Greenland Ice Sheet (GrIS) can be partitioned between surface mass balance (SMB) and discharge due to ice dynamics through its marine-terminating outlet glaciers. A perturbation to a glacier terminus (e.g. a calving event) results in an instantaneous response in velocity and mass loss, but also a diffusive response due to the evolution of ice thickness over time. This diffusive response means the total impact of a retreat event can take decades to be fully realised. Here we model the committed response of the GrIS to recent observed changes in terminus position, neglecting any future climate perturbations. Our simulations quantify the sea level contribution that is locked in due to the slow dynamic response of the ice. Using the Ice Sheet System Model (ISSM), we run forward simulations starting from an initial state representative of the 2007 ice sheet. We apply perturbations to the marine-terminating glacier termini that represent recent observed changes, and simulate the response over the 21st Century, holding the climate forcing constant. The sensitivity of the ice sheet response to model parameter uncertainty is explored with in an ensemble framework, and GRACE data is used to constrain the results. We find that terminus retreat observed between 2007 and 2015 results in approximately 6 mm of sea level rise by 2100, with retreat having a lasting impact on velocity and mass loss. Our results complement the ISMIP6 projections, which report the ice sheet response to future forcing, excluding the background committed response. In this way, we can obtain estimates of Greenland&#8217;s total contribution to sea level rise by 2100.

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