Articles | Volume 12, issue 5
Research article 04 May 2018
Research article | 04 May 2018
How dynamic are ice-stream beds?
Damon Davies et al.
No articles found.
Helen Ockenden, Robert G. Bingham, Andrew Curtis, and Daniel Goldberg
The Cryosphere Discuss.,
Preprint under review for TCShort summary
Hills and valleys hidden under the ice of Thwaites Glacier have an impact on ice flow and future ice loss, but there are not many three dimensional observations of their location or size. We apply a mathematical theory to new high resolution observations of the ice surface to predict the bed topography beneath the ice. There is a good correlation with ice-penetrating radar observations. The method may be useful in areas with few direct observations, or as a further constraint for other methods.
Alex M. Brisbourne, Michael Kendall, Sofia-Katerina Kufner, Thomas S. Hudson, and Andrew M. Smith
The Cryosphere, 15, 3443–3458,Short summary
How ice sheets flowed in the past is written into the structure and texture of the ice sheet itself. Measuring this structure and properties of the ice can help us understand the recent behaviour of the ice sheets. We use a relatively new technique, not previously attempted in Antarctica, to measure the seismic vibrations of a fibre optic cable down a borehole. We demonstrate the potential of this technique to unravel past ice flow and see hints of these complex signals from the ice flow itself.
Martin Horwath, Benjamin D. Gutknecht, Anny Cazenave, Hindumathi Kulaiappan Palanisamy, Florence Marti, Ben Marzeion, Frank Paul, Raymond Le Bris, Anna E. Hogg, Inès Otosaka, Andrew Shepherd, Petra Döll, Denise Cáceres, Hannes Müller Schmied, Johnny A. Johannessen, Jan Even Øie Nilsen, Roshin P. Raj, René Forsberg, Louise Sandberg Sørensen, Valentina R. Barletta, Sebastian B. Simonsen, Per Knudsen, Ole Baltazar Andersen, Heidi Randall, Stine K. Rose, Christopher J. Merchant, Claire R. Macintosh, Karina von Schuckmann, Kristin Novotny, Andreas Groh, Marco Restano, and Jérôme Benveniste
Earth Syst. Sci. Data Discuss.,
Preprint under review for ESSDShort summary
Global mean sea level change observed from 1993 to 2016 (at a mean rate of 3.05 mm per year) matches the combined effect of changes in water density (thermal expansion) and ocean mass. Ocean mass change is assessed through the contributions from glaciers, ice sheets and land water storage or directly from satellite data since 2003. Our budget assessments of linear trends and monthly anomalies utilise new datasets and uncertainty characterisations developed within ESA's Climate Change Initiative.
Felipe Napoleoni, Stewart S. R. Jamieson, Neil Ross, Michael J. Bentley, Andrés Rivera, Andrew M. Smith, Martin J. Siegert, Guy J. G. Paxman, Guisella Gacitúa, José A. Uribe, Rodrigo Zamora, Alex M. Brisbourne, and David G. Vaughan
The Cryosphere, 14, 4507–4524,Short summary
Subglacial water is important for ice sheet dynamics and stability. Despite this, there is a lack of detailed subglacial-water characterisation in West Antarctica (WA). We report 33 new subglacial lakes. Additionally, a new digital elevation model of basal topography was built and used to simulate the subglacial hydrological network in WA. The simulated subglacial hydrological catchments of Pine Island and Thwaites glaciers do not match precisely with their ice surface catchments.
Alex Brisbourne, Bernd Kulessa, Thomas Hudson, Lianne Harrison, Paul Holland, Adrian Luckman, Suzanne Bevan, David Ashmore, Bryn Hubbard, Emma Pearce, James White, Adam Booth, Keith Nicholls, and Andrew Smith
Earth Syst. Sci. Data, 12, 887–896,Short summary
Melting of the Larsen C Ice Shelf in Antarctica may lead to its collapse. To help estimate its lifespan we need to understand how the ocean can circulate beneath. This requires knowledge of the geometry of the sub-shelf cavity. New and existing measurements of seabed depth are integrated to produce a map of the ocean cavity beneath the ice shelf. The observed deep seabed may provide a pathway for circulation of warm ocean water but at the same time reduce rapid tidal melt at a critical location.
Robert D. Larter, Kelly A. Hogan, Claus-Dieter Hillenbrand, James A. Smith, Christine L. Batchelor, Matthieu Cartigny, Alex J. Tate, James D. Kirkham, Zoë A. Roseby, Gerhard Kuhn, Alastair G. C. Graham, and Julian A. Dowdeswell
The Cryosphere, 13, 1583–1596,Short summary
We present high-resolution bathymetry data that provide the most complete and detailed imagery of any Antarctic palaeo-ice stream bed. These data show how subglacial water was delivered to and influenced the dynamic behaviour of the ice stream. Our observations provide insights relevant to understanding the behaviour of modern ice streams and forecasting the contributions that they will make to future sea level rise.
Dominic A. Hodgson, Tom A. Jordan, Jan De Rydt, Peter T. Fretwell, Samuel A. Seddon, David Becker, Kelly A. Hogan, Andrew M. Smith, and David G. Vaughan
The Cryosphere, 13, 545–556,Short summary
The Brunt Ice Shelf in Antarctica is home to Halley VIa, the latest in a series of six British research stations that have occupied the ice shelf since 1956. A recent rapid growth of rifts in the Brunt Ice Shelf signals the onset of its largest calving event since records began. Here we consider whether this calving event will lead to a new steady state for the ice shelf or an unpinning from the bed, which could predispose it to accelerated flow or collapse.
Edward C. King, Jan De Rydt, and G. Hilmar Gudmundsson
The Cryosphere, 12, 3361–3372,Short summary
Ice shelves are thick sheets of ice floating on the ocean off the coasts of Antarctica and Greenland. They help regulate the flow of ice off the continent. Ice shelves undergo a natural cycle of seaward flow, fracture, iceberg production and regrowth. The Brunt Ice Shelf recently developed two large cracks. We used ground-penetrating radar to find out how the internal structure of the ice might influence the present crack development and the future stability of the ice shelf.
Frazer D. W. Christie, Robert G. Bingham, Noel Gourmelen, Eric J. Steig, Rosie R. Bisset, Hamish D. Pritchard, Kate Snow, and Simon F. B. Tett
The Cryosphere, 12, 2461–2479,Short summary
With a focus on the hitherto little-studied Marie Byrd Land coastline linking Antarctica's more comprehensively studied Amundsen and Ross Sea Embayments, this paper uses both satellite remote sensing (Landsat, ASTER, ICESat, and CryoSat2) and climate and ocean records (i.e. ERA-Interim, Met Office EN4 data) to examine links between ice recession, inter-decadal atmosphere-ocean forcing and other influences acting upon the Pacific-facing coastline of West Antarctica.
Dominic A. Hodgson, Kelly Hogan, James M. Smith, James A. Smith, Claus-Dieter Hillenbrand, Alastair G. C. Graham, Peter Fretwell, Claire Allen, Vicky Peck, Jan-Erik Arndt, Boris Dorschel, Christian Hübscher, Andrew M. Smith, and Robert Larter
The Cryosphere, 12, 2383–2399,Short summary
We studied the Coats Land ice margin, Antarctica, providing a multi-disciplinary geophysical assessment of the ice sheet configuration through its last advance and retreat; a description of the physical constraints on the stability of the past and present ice and future margin based on its submarine geomorphology and ice-sheet geometry; and evidence that once detached from the bed, the ice shelves in this region were predisposed to rapid retreat back to coastal grounding lines.
Adriano Lemos, Andrew Shepherd, Malcolm McMillan, Anna E. Hogg, Emma Hatton, and Ian Joughin
The Cryosphere, 12, 2087–2097,Short summary
We present time-series of ice surface velocities on four key outlet glaciers in Greenland, derived from sequential satellite imagery acquired between October 2014 and February 2017. We demonstrate it is possible to resolve seasonal and inter-annual changes in outlet glacier with an estimated certainty of 10 %. These datasets are key for the timely identification of emerging signals of dynamic imbalance and for understanding the processes driving ice velocity change.
Thomas Slater, Andrew Shepherd, Malcolm McMillan, Alan Muir, Lin Gilbert, Anna E. Hogg, Hannes Konrad, and Tommaso Parrinello
The Cryosphere, 12, 1551–1562,Short summary
We present a new digital elevation model of Antarctica derived from 6 years of elevation measurements acquired by ESA's CryoSat-2 satellite radar altimeter. We compare our elevation model to an independent set of NASA IceBridge airborne laser altimeter measurements and find the overall accuracy to be 9.5 m – a value comparable to or better than that of other models derived from satellite altimetry. The new CryoSat-2 digital elevation model of Antarctica will be made freely available.
Jan De Rydt, G. Hilmar Gudmundsson, Thomas Nagler, Jan Wuite, and Edward C. King
The Cryosphere, 12, 505–520,Short summary
We provide an unprecedented view into the dynamics of two active rifts in the Brunt Ice Shelf through a unique set of field observations, novel satellite data products, and a state-of-the-art ice flow model. We describe the evolution of fracture width and length in great detail, pushing the boundaries of both spatial and temporal coverage, and provide a deeper insight into the process of iceberg formation, which exerts an important control over the mass balance of the Antarctic Ice Sheet.
Edward C. King, Hamish D. Pritchard, and Andrew M. Smith
Earth Syst. Sci. Data, 8, 151–158,Short summary
Large, fast-moving glaciers create long, linear mounds of sediments covering large areas. Understanding how these features form has been hampered by a lack of data from the bed of modern-day ice sheets. We give a detailed view of the landscape beneath an Antarctic glacier called Rutford Ice Stream. We towed a radar system back and forth across the glacier to measure the ice thickness every few metres. This is the first place such a highly detailed view of the sub-ice landscape has been created.
S. L. Cornford, D. F. Martin, A. J. Payne, E. G. Ng, A. M. Le Brocq, R. M. Gladstone, T. L. Edwards, S. R. Shannon, C. Agosta, M. R. van den Broeke, H. H. Hellmer, G. Krinner, S. R. M. Ligtenberg, R. Timmermann, and D. G. Vaughan
The Cryosphere, 9, 1579–1600,Short summary
We used a high-resolution ice sheet model capable of resolving grounding line dynamics (BISICLES) to compute responses of the major West Antarctic ice streams to projections of ocean and atmospheric warming. This is computationally demanding, and although other groups have considered parts of West Antarctica, we think this is the first calculation for the whole region at the sub-kilometer resolution that we show is required.
P. R. Holland, A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming
The Cryosphere, 9, 1005–1024,Short summary
Antarctic Peninsula ice shelves have collapsed in recent decades. The surface of Larsen C Ice Shelf is lowering, but the cause of this has not been understood. This study uses eight radar surveys to show that the lowering is caused by both ice loss and a loss of air from the ice shelf's snowpack. At least two different processes are causing the lowering. The stability of Larsen C may be at risk from an ungrounding of Bawden Ice Rise or ice-front retreat past a 'compressive arch' in strain rates.
K. C. Rose, N. Ross, T. A. Jordan, R. G. Bingham, H. F. J. Corr, F. Ferraccioli, A. M. Le Brocq, D. M. Rippin, and M. J. Siegert
Earth Surf. Dynam., 3, 139–152,Short summary
We use ice-penetrating-radar data to identify a laterally continuous, gently sloping topographic block, comprising two surfaces separated by a distinct break in slope, preserved beneath the Institute and Möller ice streams, West Antarctica. We interpret these features as extensive erosion surfaces, showing that ancient (pre-glacial) surfaces can be preserved at low elevations beneath ice sheets. Different erosion regimes (e.g. fluvial and marine) may have formed these surfaces.
A. P. Wright, A. M. Le Brocq, S. L. Cornford, R. G. Bingham, H. F. J. Corr, F. Ferraccioli, T. A. Jordan, A. J. Payne, D. M. Rippin, N. Ross, and M. J. Siegert
The Cryosphere, 8, 2119–2134,
T. Howard, A. K. Pardaens, J. L. Bamber, J. Ridley, G. Spada, R. T. W. L. Hurkmans, J. A. Lowe, and D. Vaughan
Ocean Sci., 10, 473–483,
M. J. Siegert, N. Ross, H. Corr, B. Smith, T. Jordan, R. G. Bingham, F. Ferraccioli, D. M. Rippin, and A. Le Brocq
The Cryosphere, 8, 15–24,
A. M. Brisbourne, A. M. Smith, E. C. King, K. W. Nicholls, P. R. Holland, and K. Makinson
The Cryosphere, 8, 1–13,
P. Dutrieux, D. G. Vaughan, H. F. J. Corr, A. Jenkins, P. R. Holland, I. Joughin, and A. H. Fleming
The Cryosphere, 7, 1543–1555,
P. Fretwell, H. D. Pritchard, D. G. Vaughan, J. L. Bamber, N. E. Barrand, R. Bell, C. Bianchi, R. G. Bingham, D. D. Blankenship, G. Casassa, G. Catania, D. Callens, H. Conway, A. J. Cook, H. F. J. Corr, D. Damaske, V. Damm, F. Ferraccioli, R. Forsberg, S. Fujita, Y. Gim, P. Gogineni, J. A. Griggs, R. C. A. Hindmarsh, P. Holmlund, J. W. Holt, R. W. Jacobel, A. Jenkins, W. Jokat, T. Jordan, E. C. King, J. Kohler, W. Krabill, M. Riger-Kusk, K. A. Langley, G. Leitchenkov, C. Leuschen, B. P. Luyendyk, K. Matsuoka, J. Mouginot, F. O. Nitsche, Y. Nogi, O. A. Nost, S. V. Popov, E. Rignot, D. M. Rippin, A. Rivera, J. Roberts, N. Ross, M. J. Siegert, A. M. Smith, D. Steinhage, M. Studinger, B. Sun, B. K. Tinto, B. C. Welch, D. Wilson, D. A. Young, C. Xiangbin, and A. Zirizzotti
The Cryosphere, 7, 375–393,
F. Gillet-Chaulet, O. Gagliardini, H. Seddik, M. Nodet, G. Durand, C. Ritz, T. Zwinger, R. Greve, and D. G. Vaughan
The Cryosphere, 6, 1561–1576,
Related subject area
Discipline: Ice sheets | Subject: GeomorphologyFormation of ribbed bedforms below shear margins and lobes of palaeo-ice streamsA quasi-annual record of time-transgressive esker formation: implications for ice-sheet reconstruction and subglacial hydrologyIce-stream flow switching by up-ice propagation of instabilities along glacial marginal troughsBasal control of supraglacial meltwater catchments on the Greenland Ice SheetSubglacial drainage patterns of Devon Island, Canada: detailed comparison of rivers and subglacial meltwater channels
Jean Vérité, Édouard Ravier, Olivier Bourgeois, Stéphane Pochat, Thomas Lelandais, Régis Mourgues, Christopher D. Clark, Paul Bessin, David Peigné, and Nigel Atkinson
The Cryosphere, 15, 2889–2916,Short summary
Subglacial bedforms are commonly used to reconstruct past glacial dynamics and investigate processes occuring at the ice–bed interface. Using analogue modelling and geomorphological mapping, we demonstrate that ridges with undulating crests, known as subglacial ribbed bedforms, are ubiquitous features along ice stream corridors. These bedforms provide a tantalizing glimpse into (1) the former positions of ice stream margins, (2) the ice lobe dynamics and (3) the meltwater drainage efficiency.
Stephen J. Livingstone, Emma L. M. Lewington, Chris D. Clark, Robert D. Storrar, Andrew J. Sole, Isabelle McMartin, Nico Dewald, and Felix Ng
The Cryosphere, 14, 1989–2004,Short summary
We map series of aligned mounds (esker beads) across central Nunavut, Canada. Mounds are interpreted to have formed roughly annually as sediment carried by subglacial rivers is deposited at the ice margin. Chains of mounds are formed as the ice retreats. This high-resolution (annual) record allows us to constrain the pace of ice retreat, sediment fluxes, and the style of drainage through time. In particular, we suggest that eskers in general record a composite signature of ice-marginal drainage.
Etienne Brouard and Patrick Lajeunesse
The Cryosphere, 13, 981–996,Short summary
Modifications in ice-stream networks have major impacts on ice sheet mass balance and global sea level. However, the mechanisms controlling ice-stream switching remain poorly understood. We report a flow switch in an ice-stream system that occurred on the Baffin Island shelf through the erosion of a marginal trough. Up-ice propagation of ice streams through marginal troughs can lead to the piracy of neighboring ice catchments, which induces an adjacent ice-stream switch and shutdown.
Josh Crozier, Leif Karlstrom, and Kang Yang
The Cryosphere, 12, 3383–3407,Short summary
Understanding ice sheet surface meltwater routing is important for modeling and predicting ice sheet evolution. We determined that bed topography underlying the Greenland Ice Sheet is the primary influence on 1–10 km scale ice surface topography, and on drainage-basin-scale surface meltwater routing. We provide a simple means of predicting the response of surface meltwater routing to changing ice flow conditions and explore the implications of this for subglacial hydrology.
Anna Grau Galofre, A. Mark Jellinek, Gordon R. Osinski, Michael Zanetti, and Antero Kukko
The Cryosphere, 12, 1461–1478,Short summary
Water accumulated at the base of ice sheets is the main driver of glacier acceleration and loss of ice mass in Arctic regions. Previously glaciated landscapes sculpted by this water carry information about how ice sheets collapse and ultimately disappear. The search for these landscapes took us to the high Arctic, to explore channels that formed under kilometers of ice during the last ice age. In this work we describe how subglacial channels look and how they helped to drain an ice sheet.
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This paper investigates the dynamics of ice stream beds using repeat geophysical surveys of the bed of Pine Island Glacier, West Antarctica; 60 km of the bed was surveyed, comprising the most extensive repeat ground-based geophysical surveys of an Antarctic ice stream; 90 % of the surveyed bed shows no significant change despite the glacier increasing in speed by up to 40 % over the last decade. This result suggests that ice stream beds are potentially more stable than previously suggested.
This paper investigates the dynamics of ice stream beds using repeat geophysical surveys of the...