Articles | Volume 10, issue 1
https://doi.org/10.5194/tc-10-193-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/tc-10-193-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
21 Jan 2016
Research article |
| 21 Jan 2016
Sheet, stream, and shelf flow as progressive ice-bed uncoupling: Byrd Glacier, Antarctica and Jakobshavn Isbrae, Greenland
T. Hughes
CORRESPONDING AUTHOR
School of Earth and Climate Sciences, Climate Change Institute,
University of Maine, Orono, ME, USA
A. Sargent
School of Science and Humanities, Husson University, Bangor, ME, USA
J. Fastook
Computer Sciences Department, Climate Change Institute
University of Maine, Orono, ME, USA
K. Purdon
Center for Remote Sensing of Ice Sheets, School of Engineering,
University of Kansas, Lawrence, KS, USA
Center for Remote Sensing of Ice Sheets, School of Engineering,
University of Kansas, Lawrence, KS, USA
J.-B. Yan
Center for Remote Sensing of Ice Sheets, School of Engineering,
University of Kansas, Lawrence, KS, USA
S. Gogineni
Center for Remote Sensing of Ice Sheets, School of Engineering,
University of Kansas, Lawrence, KS, USA
Related authors
Zhongshi Zhang, Qing Yan, Elizabeth J. Farmer, Camille Li, Gilles Ramstein, Terence Hughes, Martin Jakobsson, Matt O'Regan, Ran Zhang, Ning Tan, Camille Contoux, Christophe Dumas, and Chuncheng Guo
Clim. Past Discuss., https://doi.org/10.5194/cp-2018-79, https://doi.org/10.5194/cp-2018-79, 2018
Revised manuscript not accepted
Short summary
Short summary
Our study challenges the widely accepted idea that the Laurentide-Eurasian ice sheets gradually extended across North America and Northwest Eurasia, and suggests the growth of the NH ice sheets is much more complicated. We find climate feedbacks regulate the distribution of the NH ice sheets, producing swings between two distinct ice sheet configurations: the Laurentide-Eurasian and a circum-Arctic configuration, where large ice sheets existed over Northeast Siberia and the Canadian Rockies.
Terence J. Hughes
The Cryosphere, 11, 1685–1689, https://doi.org/10.5194/tc-11-1685-2017, https://doi.org/10.5194/tc-11-1685-2017, 2017
Short summary
Short summary
Two approaches to ice-sheet modeling are available. Analytical modeling is the traditional approach. It solves the force (momentum), mass, and energy balances to obtain three-dimensional solutions over time. Geometrical modeling employs simple geometry to solve the force and mass balance in one dimension along ice flow. It is useful primarily to provide the first-order physical basis of ice-sheet modeling for students with little background in mathematics. The two approaches are compared.
T. Hughes, A. Sargent, J. Fastook, K. Purdon, J. Li, J.-B. Yan, and S. Gogineni
The Cryosphere Discuss., https://doi.org/10.5194/tcd-8-2043-2014, https://doi.org/10.5194/tcd-8-2043-2014, 2014
Revised manuscript not accepted
Renée M. Fredensborg Hansen, Henriette Skourup, Eero Rinne, Arttu Jutila, Isobel R. Lawrence, Andrew Shepherd, Knut V. Høyland, Jilu Li, Fernando Rodriguez-Morales, Sebastian B. Simonsen, Jeremy Wilkinson, Gaelle Veyssiere, Donghui Yi, René Forsberg, and Taniâ G. D. Casal
EGUsphere, https://doi.org/10.5194/egusphere-2024-2854, https://doi.org/10.5194/egusphere-2024-2854, 2024
Short summary
Short summary
In December 2022, an airborne campaign collected unprecedented coincident multi-frequency radar and lidar data over sea ice along a CryoSat-2 and ICESat-2 (CRYO2ICE) orbit in the Weddell Sea useful for evaluating microwave penetration. We found limited snow penetration at Ka- and Ku-bands, with significant contributions from the air-snow interface, contradicting traditional assumptions. These findings challenge current methods for comparing air- and spaceborne altimeter estimates of sea ice.
Isobel Rowell, Carlos Martin, Robert Mulvaney, Helena Pryer, Dieter Tetzner, Emily Doyle, Hara Madhav Talasila, Jilu Li, and Eric Wolff
Clim. Past, 19, 1699–1714, https://doi.org/10.5194/cp-19-1699-2023, https://doi.org/10.5194/cp-19-1699-2023, 2023
Short summary
Short summary
We present an age scale for a new type of ice core from a vulnerable region in West Antarctic, which is lacking in longer-term (greater than a few centuries) ice core records. The Sherman Island core extends to greater than 1 kyr. We provide modelling evidence for the potential of a 10 kyr long core. We show that this new type of ice core can be robustly dated and that climate records from this core will be a significant addition to existing regional climate records.
Jilu Li, Fernando Rodriguez-Morales, Xavier Fettweis, Oluwanisola Ibikunle, Carl Leuschen, John Paden, Daniel Gomez-Garcia, and Emily Arnold
The Cryosphere, 17, 175–193, https://doi.org/10.5194/tc-17-175-2023, https://doi.org/10.5194/tc-17-175-2023, 2023
Short summary
Short summary
Alaskan glaciers' loss of ice mass contributes significantly to ocean surface rise. It is important to know how deeply and how much snow accumulates on these glaciers to comprehend and analyze the glacial mass loss process. We reported the observed seasonal snow depth distribution from our radar data taken in Alaska in 2018 and 2021, developed a method to estimate the annual snow accumulation rate at Mt. Wrangell caldera, and identified transition zones from wet-snow zones to ablation zones.
Jilu Li, Jose A. Vélez González, Carl Leuschen, Ayyangar Harish, Prasad Gogineni, Maurine Montagnat, Ilka Weikusat, Fernando Rodriguez-Morales, and John Paden
The Cryosphere, 12, 2689–2705, https://doi.org/10.5194/tc-12-2689-2018, https://doi.org/10.5194/tc-12-2689-2018, 2018
Short summary
Short summary
Ice properties inferred from multi-polarization measurements can provide insight into ice strain, viscosity, and ice flow. The Center for Remote Sensing of Ice Sheets used a ground-based radar for multi-channel and multi-polarization measurements at the NEEM site. This paper describes the radar system, antenna configurations, data collection, and processing and analysis of this data set. Comparisons between the radar observations, simulations, and ice core fabric data are in very good agreement.
Zhongshi Zhang, Qing Yan, Elizabeth J. Farmer, Camille Li, Gilles Ramstein, Terence Hughes, Martin Jakobsson, Matt O'Regan, Ran Zhang, Ning Tan, Camille Contoux, Christophe Dumas, and Chuncheng Guo
Clim. Past Discuss., https://doi.org/10.5194/cp-2018-79, https://doi.org/10.5194/cp-2018-79, 2018
Revised manuscript not accepted
Short summary
Short summary
Our study challenges the widely accepted idea that the Laurentide-Eurasian ice sheets gradually extended across North America and Northwest Eurasia, and suggests the growth of the NH ice sheets is much more complicated. We find climate feedbacks regulate the distribution of the NH ice sheets, producing swings between two distinct ice sheet configurations: the Laurentide-Eurasian and a circum-Arctic configuration, where large ice sheets existed over Northeast Siberia and the Canadian Rockies.
Hafeez Jeofry, Neil Ross, Hugh F. J. Corr, Jilu Li, Mathieu Morlighem, Prasad Gogineni, and Martin J. Siegert
Earth Syst. Sci. Data, 10, 711–725, https://doi.org/10.5194/essd-10-711-2018, https://doi.org/10.5194/essd-10-711-2018, 2018
Short summary
Short summary
Accurately characterizing the complexities of the ice-sheet dynamic specifically close to the grounding line across the Weddell Sea (WS) sector in the ice-sheet models provides challenges to the scientific community. Our main objective is to comprehend these complexities, adding accuracy to the projection of future ice-sheet dynamics. Therefore, we have developed a new bed elevation digital elevation model across the WS sector, which will be of value to ice-sheet modelling experiments.
Terence J. Hughes
The Cryosphere, 11, 1685–1689, https://doi.org/10.5194/tc-11-1685-2017, https://doi.org/10.5194/tc-11-1685-2017, 2017
Short summary
Short summary
Two approaches to ice-sheet modeling are available. Analytical modeling is the traditional approach. It solves the force (momentum), mass, and energy balances to obtain three-dimensional solutions over time. Geometrical modeling employs simple geometry to solve the force and mass balance in one dimension along ice flow. It is useful primarily to provide the first-order physical basis of ice-sheet modeling for students with little background in mathematics. The two approaches are compared.
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, https://doi.org/10.5194/tc-9-1005-2015, https://doi.org/10.5194/tc-9-1005-2015, 2015
Short summary
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.
A. Levermann, R. Winkelmann, S. Nowicki, J. L. Fastook, K. Frieler, R. Greve, H. H. Hellmer, M. A. Martin, M. Meinshausen, M. Mengel, A. J. Payne, D. Pollard, T. Sato, R. Timmermann, W. L. Wang, and R. A. Bindschadler
Earth Syst. Dynam., 5, 271–293, https://doi.org/10.5194/esd-5-271-2014, https://doi.org/10.5194/esd-5-271-2014, 2014
P. Schmidt, B. Lund, J-O. Näslund, and J. Fastook
Solid Earth, 5, 371–388, https://doi.org/10.5194/se-5-371-2014, https://doi.org/10.5194/se-5-371-2014, 2014
T. Hughes, A. Sargent, J. Fastook, K. Purdon, J. Li, J.-B. Yan, and S. Gogineni
The Cryosphere Discuss., https://doi.org/10.5194/tcd-8-2043-2014, https://doi.org/10.5194/tcd-8-2043-2014, 2014
Revised manuscript not accepted
A. Sargent and J. L. Fastook
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmdd-7-1829-2014, https://doi.org/10.5194/gmdd-7-1829-2014, 2014
Revised manuscript has not been submitted
J. Kleman, J. Fastook, K. Ebert, J. Nilsson, and R. Caballero
Clim. Past, 9, 2365–2378, https://doi.org/10.5194/cp-9-2365-2013, https://doi.org/10.5194/cp-9-2365-2013, 2013
J. L. Bamber, J. A. Griggs, R. T. W. L. Hurkmans, J. A. Dowdeswell, S. P. Gogineni, I. Howat, J. Mouginot, J. Paden, S. Palmer, E. Rignot, and D. Steinhage
The Cryosphere, 7, 499–510, https://doi.org/10.5194/tc-7-499-2013, https://doi.org/10.5194/tc-7-499-2013, 2013
Related subject area
Ice Sheets
Probabilistic projections of the Amery Ice Shelf catchment, Antarctica, under conditions of high ice-shelf basal melt
Reconstructing dynamics of the Baltic Ice Stream Complex during deglaciation of the Last Scandinavian Ice Sheet
The influence of firn-layer material properties on surface crevasse propagation in glaciers and ice shelves
Assessing the potential for ice flow piracy between the Totten and Vanderford glaciers, East Antarctica
Stagnant ice and age modelling in the Dome C region, Antarctica
Polar firn properties in Greenland and Antarctica and related effects on microwave brightness temperatures
A model of the weathering crust and microbial activity on an ice-sheet surface
PISM-LakeCC: Implementing an adaptive proglacial lake boundary in an ice sheet model
Remapping of Greenland ice sheet surface mass balance anomalies for large ensemble sea-level change projections
Brief communication: On calculating the sea-level contribution in marine ice-sheet models
A simple stress-based cliff-calving law
Scaling of instability timescales of Antarctic outlet glaciers based on one-dimensional similitude analysis
A statistical fracture model for Antarctic ice shelves and glaciers
Modelled fracture and calving on the Totten Ice Shelf
Design and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison
Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years
Influence of temperature fluctuations on equilibrium
ice sheet volume
GPS-derived estimates of surface mass balance and ocean-induced basal melt for Pine Island Glacier ice shelf, Antarctica
Analysis of ice shelf flexure and its InSAR representation in the grounding zone of the southern McMurdo Ice Shelf
Boundary layer models for calving marine outlet glaciers
Liquid water content in ice estimated through a full-depth ground radar profile and borehole measurements in western Greenland
Dynamic influence of pinning points on marine ice-sheet stability: a numerical study in Dronning Maud Land, East Antarctica
Persistence and variability of ice-stream grounding lines on retrograde bed slopes
Similitude of ice dynamics against scaling of geometry and physical parameters
An ice-sheet-wide framework for englacial attenuation from ice-penetrating radar data
Inversion of geothermal heat flux in a thermomechanically coupled nonlinear Stokes ice sheet model
The influence of a model subglacial lake on ice dynamics and internal layering
SeaRISE experiments revisited: potential sources of spread in multi-model projections of the Greenland ice sheet
Elevation change of the Greenland Ice Sheet due to surface mass balance and firn processes, 1960–2014
Ice sheet mass loss caused by dust and black carbon accumulation
Temporal variations in the flow of a large Antarctic ice stream controlled by tidally induced changes in the subglacial water system
Evolution of ice-shelf channels in Antarctic ice shelves
Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning
How do icebergs affect the Greenland ice sheet under pre-industrial conditions? – a model study with a fully coupled ice-sheet–climate model
Seismic wave propagation in anisotropic ice – Part 1: Elasticity tensor and derived quantities from ice-core properties
Seismic wave propagation in anisotropic ice – Part 2: Effects of crystal anisotropy in geophysical data
Simulating the Greenland ice sheet under present-day and palaeo constraints including a new discharge parameterization
Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2
The importance of insolation changes for paleo ice sheet modeling
Parameterization of basal friction near grounding lines in a one-dimensional ice sheet model
A range correction for ICESat and its potential impact on ice-sheet mass balance studies
Brief Communication: Further summer speedup of Jakobshavn Isbræ
Creep deformation and buttressing capacity of damaged ice shelves: theory and application to Larsen C ice shelf
Scatter of mass changes estimates at basin scale for Greenland and Antarctica
Influence of ice-sheet geometry and supraglacial lakes on seasonal ice-flow variability
Hindcasting to measure ice sheet model sensitivity to initial states
Surface undulations of Antarctic ice streams tightly controlled by bedrock topography
Manufactured solutions and the verification of three-dimensional Stokes ice-sheet models
Greenland ice sheet contribution to sea-level rise from a new-generation ice-sheet model
Radar diagnosis of the subglacial conditions in Dronning Maud Land, East Antarctica
Sanket Jantre, Matthew J. Hoffman, Nathan M. Urban, Trevor Hillebrand, Mauro Perego, Stephen Price, and John D. Jakeman
The Cryosphere, 18, 5207–5238, https://doi.org/10.5194/tc-18-5207-2024, https://doi.org/10.5194/tc-18-5207-2024, 2024
Short summary
Short summary
We investigate potential sea-level rise from Antarctica's Lambert Glacier, once considered stable but now at risk due to projected ocean warming by 2100. Using statistical methods and limited supercomputer simulations, we calibrated our ice-sheet model using three observables. We find that, under high greenhouse gas emissions, glacier retreat could raise sea levels by 46–133 mm by 2300. This study highlights the need for better observations to reduce uncertainty in ice-sheet model projections.
Izabela Szuman, Jakub Z. Kalita, Christiaan R. Diemont, Stephen J. Livingstone, Chris D. Clark, and Martin Margold
The Cryosphere, 18, 2407–2428, https://doi.org/10.5194/tc-18-2407-2024, https://doi.org/10.5194/tc-18-2407-2024, 2024
Short summary
Short summary
A Baltic-wide glacial landform-based map is presented, filling in a geographical gap in the record that has been speculated about by palaeoglaciologists for over a century. Here we used newly available bathymetric data and provide landform evidence of corridors of fast ice flow that we interpret as ice streams. Where previous ice-sheet-scale investigations inferred a single ice source, our mapping identifies flow and ice margin geometries from both Swedish and Bothnian sources.
Theo Clayton, Ravindra Duddu, Tim Hageman, and Emilio Martinez-Paneda
EGUsphere, https://doi.org/10.5194/egusphere-2024-660, https://doi.org/10.5194/egusphere-2024-660, 2024
Short summary
Short summary
We develop and validate new analytical solutions that quantitatively consider how the properties of ice vary along the depth of ice shelves and can be readily used in existing ice sheet models. Depth-varying firn properties are found to have a profound impact on ice sheet fracture and calving events. Our results show that grounded glaciers are less vulnerable than previously anticipated while floating ice shelves are significantly more vulnerable to fracture and calving.
Felicity S. McCormack, Jason L. Roberts, Bernd Kulessa, Alan Aitken, Christine F. Dow, Lawrence Bird, Benjamin K. Galton-Fenzi, Katharina Hochmuth, Richard S. Jones, Andrew N. Mackintosh, and Koi McArthur
The Cryosphere, 17, 4549–4569, https://doi.org/10.5194/tc-17-4549-2023, https://doi.org/10.5194/tc-17-4549-2023, 2023
Short summary
Short summary
Changes in Antarctic surface elevation can cause changes in ice and basal water flow, impacting how much ice enters the ocean. We find that ice and basal water flow could divert from the Totten to the Vanderford Glacier, East Antarctica, under only small changes in the surface elevation, with implications for estimates of ice loss from this region. Further studies are needed to determine when this could occur and if similar diversions could occur elsewhere in Antarctica due to climate change.
Ailsa Chung, Frédéric Parrenin, Daniel Steinhage, Robert Mulvaney, Carlos Martín, Marie G. P. Cavitte, David A. Lilien, Veit Helm, Drew Taylor, Prasad Gogineni, Catherine Ritz, Massimo Frezzotti, Charles O'Neill, Heinrich Miller, Dorthe Dahl-Jensen, and Olaf Eisen
The Cryosphere, 17, 3461–3483, https://doi.org/10.5194/tc-17-3461-2023, https://doi.org/10.5194/tc-17-3461-2023, 2023
Short summary
Short summary
We combined a numerical model with radar measurements in order to determine the age of ice in the Dome C region of Antarctica. Our results show that at the current ice core drilling sites on Little Dome C, the maximum age of the ice is almost 1.5 Ma. We also highlight a new potential drill site called North Patch with ice up to 2 Ma. Finally, we explore the nature of a stagnant ice layer at the base of the ice sheet which has been independently observed and modelled but is not well understood.
Haokui Xu, Brooke Medley, Leung Tsang, Joel T. Johnson, Kenneth C. Jezek, Macro Brogioni, and Lars Kaleschke
The Cryosphere, 17, 2793–2809, https://doi.org/10.5194/tc-17-2793-2023, https://doi.org/10.5194/tc-17-2793-2023, 2023
Short summary
Short summary
The density profile of polar ice sheets is a major unknown in estimating the mass loss using lidar tomography methods. In this paper, we show that combing the active radar data and passive radiometer data can provide an estimation of density properties using the new model we implemented in this paper. The new model includes the short and long timescale variations in the firn and also the refrozen layers which are not included in the previous modeling work.
Tilly Woods and Ian J. Hewitt
The Cryosphere, 17, 1967–1987, https://doi.org/10.5194/tc-17-1967-2023, https://doi.org/10.5194/tc-17-1967-2023, 2023
Short summary
Short summary
Solar radiation causes melting at and just below the surface of the Greenland ice sheet, forming a porous surface layer known as the weathering crust. The weathering crust is home to many microbes, and the growth of these microbes is linked to the melting of the weathering crust and vice versa. We use a mathematical model to investigate what controls the size and structure of the weathering crust, the number of microbes within it, and its sensitivity to climate change.
Sebastian Hinck, Evan J. Gowan, Xu Zhang, and Gerrit Lohmann
The Cryosphere, 16, 941–965, https://doi.org/10.5194/tc-16-941-2022, https://doi.org/10.5194/tc-16-941-2022, 2022
Short summary
Short summary
Proglacial lakes were pervasive along the retreating continental ice margins after the Last Glacial Maximum. Similarly to the marine ice boundary, interactions at the ice-lake interface impact ice sheet dynamics and mass balance. Previous numerical ice sheet modeling studies did not include a dynamical lake boundary. We describe the implementation of an adaptive lake boundary condition in PISM and apply the model to the glacial retreat of the Laurentide Ice Sheet.
Heiko Goelzer, Brice P. Y. Noël, Tamsin L. Edwards, Xavier Fettweis, Jonathan M. Gregory, William H. Lipscomb, Roderik S. W. van de Wal, and Michiel R. van den Broeke
The Cryosphere, 14, 1747–1762, https://doi.org/10.5194/tc-14-1747-2020, https://doi.org/10.5194/tc-14-1747-2020, 2020
Short summary
Short summary
Future sea-level change projections with process-based ice sheet models are typically driven with surface mass balance forcing derived from climate models. In this work we address the problems arising from a mismatch of the modelled ice sheet geometry with the one used by the climate model. The proposed remapping method reproduces the original forcing data closely when applied to the original geometry and produces a physically meaningful forcing when applied to different modelled geometries.
Heiko Goelzer, Violaine Coulon, Frank Pattyn, Bas de Boer, and Roderik van de Wal
The Cryosphere, 14, 833–840, https://doi.org/10.5194/tc-14-833-2020, https://doi.org/10.5194/tc-14-833-2020, 2020
Short summary
Short summary
In our ice-sheet modelling experience and from exchange with colleagues in different groups, we found that it is not always clear how to calculate the sea-level contribution from a marine ice-sheet model. This goes hand in hand with a lack of documentation and transparency in the published literature on how the sea-level contribution is estimated in different models. With this brief communication, we hope to stimulate awareness and discussion in the community to improve on this situation.
Tanja Schlemm and Anders Levermann
The Cryosphere, 13, 2475–2488, https://doi.org/10.5194/tc-13-2475-2019, https://doi.org/10.5194/tc-13-2475-2019, 2019
Short summary
Short summary
We provide a simple stress-based parameterization for cliff calving of ice sheets. According to the resulting increasing dependence of the calving rate on ice thickness, the parameterization might lead to a runaway ice loss in large parts of Greenland and Antarctica.
Anders Levermann and Johannes Feldmann
The Cryosphere, 13, 1621–1633, https://doi.org/10.5194/tc-13-1621-2019, https://doi.org/10.5194/tc-13-1621-2019, 2019
Short summary
Short summary
Using scaling analysis we propose that the currently observed marine ice-sheet instability in the Amundsen Sea sector might be faster than all other potential instabilities in Antarctica.
Veronika Emetc, Paul Tregoning, Mathieu Morlighem, Chris Borstad, and Malcolm Sambridge
The Cryosphere, 12, 3187–3213, https://doi.org/10.5194/tc-12-3187-2018, https://doi.org/10.5194/tc-12-3187-2018, 2018
Short summary
Short summary
The paper includes a model that can be used to predict zones of fracture formation in both floating and grounded ice in Antarctica. We used observations and a statistics-based model to predict fractures in most ice shelves in Antarctica as an alternative to the damage-based approach. We can predict the location of observed fractures with an average success rate of 84% for grounded ice and 61% for floating ice and mean overestimation error of 26% and 20%, respectively.
Sue Cook, Jan Åström, Thomas Zwinger, Benjamin Keith Galton-Fenzi, Jamin Stevens Greenbaum, and Richard Coleman
The Cryosphere, 12, 2401–2411, https://doi.org/10.5194/tc-12-2401-2018, https://doi.org/10.5194/tc-12-2401-2018, 2018
Short summary
Short summary
The growth of fractures on Antarctic ice shelves is important because it controls the amount of ice lost as icebergs. We use a model constructed of multiple interconnected blocks to predict the locations where fractures will form on the Totten Ice Shelf in East Antarctica. The results show that iceberg calving is controlled not only by fractures forming near the front of the ice shelf but also by fractures which formed many kilometres upstream.
Heiko Goelzer, Sophie Nowicki, Tamsin Edwards, Matthew Beckley, Ayako Abe-Ouchi, Andy Aschwanden, Reinhard Calov, Olivier Gagliardini, Fabien Gillet-Chaulet, Nicholas R. Golledge, Jonathan Gregory, Ralf Greve, Angelika Humbert, Philippe Huybrechts, Joseph H. Kennedy, Eric Larour, William H. Lipscomb, Sébastien Le clec'h, Victoria Lee, Mathieu Morlighem, Frank Pattyn, Antony J. Payne, Christian Rodehacke, Martin Rückamp, Fuyuki Saito, Nicole Schlegel, Helene Seroussi, Andrew Shepherd, Sainan Sun, Roderik van de Wal, and Florian A. Ziemen
The Cryosphere, 12, 1433–1460, https://doi.org/10.5194/tc-12-1433-2018, https://doi.org/10.5194/tc-12-1433-2018, 2018
Short summary
Short summary
We have compared a wide spectrum of different initialisation techniques used in the ice sheet modelling community to define the modelled present-day Greenland ice sheet state as a starting point for physically based future-sea-level-change projections. Compared to earlier community-wide comparisons, we find better agreement across different models, which implies overall improvement of our understanding of what is needed to produce such initial states.
Alex S. Gardner, Geir Moholdt, Ted Scambos, Mark Fahnstock, Stefan Ligtenberg, Michiel van den Broeke, and Johan Nilsson
The Cryosphere, 12, 521–547, https://doi.org/10.5194/tc-12-521-2018, https://doi.org/10.5194/tc-12-521-2018, 2018
Short summary
Short summary
We map present-day Antarctic surface velocities from Landsat imagery and compare to earlier estimates from radar. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and the western Antarctic Peninsula, account for 89 % of the observed increase in ice discharge. In contrast, glaciers draining the East Antarctic have been remarkably stable. Our work suggests that patterns of mass loss are part of a longer-term phase of enhanced flow.
ice sheet volume
Troels Bøgeholm Mikkelsen, Aslak Grinsted, and Peter Ditlevsen
The Cryosphere, 12, 39–47, https://doi.org/10.5194/tc-12-39-2018, https://doi.org/10.5194/tc-12-39-2018, 2018
Short summary
Short summary
The atmospheric temperature increase poses a real risk of ice sheets collapsing. We show that this risk might have been underestimated since variations in temperature will move the ice sheets to the tipping point of destabilization.
We show this by using a simple computer model of a large ice sheet and investigate what happens if the temperature varies from year to year. The total volume of the ice sheet decreases because a cold year followed by an equally warm year do not cancel out.
David E. Shean, Knut Christianson, Kristine M. Larson, Stefan R. M. Ligtenberg, Ian R. Joughin, Ben E. Smith, C. Max Stevens, Mitchell Bushuk, and David M. Holland
The Cryosphere, 11, 2655–2674, https://doi.org/10.5194/tc-11-2655-2017, https://doi.org/10.5194/tc-11-2655-2017, 2017
Short summary
Short summary
We used long-term GPS data and interferometric reflectometry (GPS-IR) to measure velocity, strain rate and surface elevation for the PIG ice shelf – a site of significant mass loss in recent decades. We combined these observations with high-res DEMs and firn model output to constrain surface mass balance and basal melt rates. We document notable spatial variability in basal melt rates but limited temporal variability from 2012 to 2014 despite significant changes in sub-shelf ocean heat content.
Wolfgang Rack, Matt A. King, Oliver J. Marsh, Christian T. Wild, and Dana Floricioiu
The Cryosphere, 11, 2481–2490, https://doi.org/10.5194/tc-11-2481-2017, https://doi.org/10.5194/tc-11-2481-2017, 2017
Short summary
Short summary
Predicting changes of the Antarctic Ice Sheet involves fully understanding ice dynamics at the transition between grounded and floating ice. We map tidal bending of ice by satellite using InSAR, and we use precise GPS measurements with assumptions of tidal elastic bending to better interpret the satellite signal. It allows us to better define the grounding-line position and to refine the shape of tidal flexure profiles.
Christian Schoof, Andrew D. Davis, and Tiberiu V. Popa
The Cryosphere, 11, 2283–2303, https://doi.org/10.5194/tc-11-2283-2017, https://doi.org/10.5194/tc-11-2283-2017, 2017
Short summary
Short summary
We show mathematically and computationally how discharge of ice from ocean-terminating glaciers is controlled by a combination of different forces acting on ice near the grounding line of a glacier and how that combination of forces is affected by the process of iceberg formation, which limits the length of floating ice tongues extending in front of the glacier. We show that a deeper fjord may lead to a longer ice tongue providing greater drag on the glacier, slowing the rate of ice discharge.
Joel Brown, Joel Harper, and Neil Humphrey
The Cryosphere, 11, 669–679, https://doi.org/10.5194/tc-11-669-2017, https://doi.org/10.5194/tc-11-669-2017, 2017
Short summary
Short summary
We use ground-penetrating radar surveys in conjunction with borehole depth and temperature data to estimate the liquid water content (wetness) of glacial ice in the ablation zone of an outlet glacier on the western side of the Greenland Ice Sheet. Our results show that the wetness of a warm basal ice layer is approximately 2.9 % to 4.6 % in our study region. This high level of wetness requires special attention when modelling ice dynamics or estimating ice thickness in the region.
Lionel Favier, Frank Pattyn, Sophie Berger, and Reinhard Drews
The Cryosphere, 10, 2623–2635, https://doi.org/10.5194/tc-10-2623-2016, https://doi.org/10.5194/tc-10-2623-2016, 2016
Short summary
Short summary
We demonstrate the short-term unstable retreat of an East Antarctic outlet glacier triggered by imposed sub-ice-shelf melt, compliant with current values, using a state-of-the-art ice-sheet model. We show that pinning points – topographic highs in contact with the ice-shelf base – have a major impact on ice-sheet stability and timing of grounding-line retreat. The study therefore calls for improving our knowledge of sub-ice-shelf bathymetry in order to reduce uncertainties in future ice loss.
Alexander A. Robel, Christian Schoof, and Eli Tziperman
The Cryosphere, 10, 1883–1896, https://doi.org/10.5194/tc-10-1883-2016, https://doi.org/10.5194/tc-10-1883-2016, 2016
Short summary
Short summary
Portions of the Antarctic Ice Sheet edge that rest on upward-sloping beds have the potential to collapse irreversibly and raise global sea level. Using a numerical model, we show that changes in the slipperiness of sediments beneath fast-flowing ice streams can cause them to persist on upward-sloping beds for hundreds to thousands of years before reversing direction. This type of behavior is important to consider as a possibility when interpreting observations of ongoing ice sheet change.
Johannes Feldmann and Anders Levermann
The Cryosphere, 10, 1753–1769, https://doi.org/10.5194/tc-10-1753-2016, https://doi.org/10.5194/tc-10-1753-2016, 2016
T. M. Jordan, J. L. Bamber, C. N. Williams, J. D. Paden, M. J. Siegert, P. Huybrechts, O. Gagliardini, and F. Gillet-Chaulet
The Cryosphere, 10, 1547–1570, https://doi.org/10.5194/tc-10-1547-2016, https://doi.org/10.5194/tc-10-1547-2016, 2016
Short summary
Short summary
Ice penetrating radar enables determination of the basal properties of ice sheets. Existing algorithms assume stationarity in the attenuation rate, which is not justifiable at an ice sheet scale. We introduce the first ice-sheet-wide algorithm for radar attenuation that incorporates spatial variability, using the temperature field from a numerical model as an initial guess. The study is a step toward ice-sheet-wide data products for basal properties and evaluation of model temperature fields.
Hongyu Zhu, Noemi Petra, Georg Stadler, Tobin Isaac, Thomas J. R. Hughes, and Omar Ghattas
The Cryosphere, 10, 1477–1494, https://doi.org/10.5194/tc-10-1477-2016, https://doi.org/10.5194/tc-10-1477-2016, 2016
Short summary
Short summary
We study how well the basal geothermal heat flux can be inferred from surface velocity observations using a thermomechanically coupled nonlinear Stokes ice sheet model. The prospects and limitations of this inversion is studied in two and three dimensional model problems. We also argue that a one-way coupled approach for the adjoint equations motivated by staggered solvers for forward multiphysics problems can lead to an incorrect gradient and premature termination of the optimization iteration.
Eythor Gudlaugsson, Angelika Humbert, Thomas Kleiner, Jack Kohler, and Karin Andreassen
The Cryosphere, 10, 751–760, https://doi.org/10.5194/tc-10-751-2016, https://doi.org/10.5194/tc-10-751-2016, 2016
Short summary
Short summary
This paper explores the influence of a subglacial lake on ice dynamics and internal layers by means of numerical modelling as well as simulating the effect of a subglacial drainage event on isochrones. We provide an explanation for characteristic dip and ridge features found at the edges of many subglacial lakes and conclude that draining lakes can result in travelling waves at depth within isochrones, thus indicating the possibility of detecting past drainage events with ice penetrating radar.
F. Saito, A. Abe-Ouchi, K. Takahashi, and H. Blatter
The Cryosphere, 10, 43–63, https://doi.org/10.5194/tc-10-43-2016, https://doi.org/10.5194/tc-10-43-2016, 2016
Short summary
Short summary
This article, as the title denotes, is a follow-up study of an ice-sheet intercomparison project SeaRISE, which focuses on the response of the Greenland ice sheet to future global warming. The projections of the different SeaRISE prticipants show diversion, which has not been examined in detail to date. This study detects the main sources of the diversion by a number of sensitivity experiments and shows the importance of initialization methods as well as climate forcing methods.
P. Kuipers Munneke, S. R. M. Ligtenberg, B. P. Y. Noël, I. M. Howat, J. E. Box, E. Mosley-Thompson, J. R. McConnell, K. Steffen, J. T. Harper, S. B. Das, and M. R. van den Broeke
The Cryosphere, 9, 2009–2025, https://doi.org/10.5194/tc-9-2009-2015, https://doi.org/10.5194/tc-9-2009-2015, 2015
Short summary
Short summary
The snow layer on top of the Greenland Ice Sheet is changing: it is thickening in the high and cold interior due to increased snowfall, while it is thinning around the margins. The marginal thinning is caused by compaction, and by more melt.
This knowledge is important: there are satellites that measure volume change of the ice sheet. It can be caused by increased ice discharge, or by compaction of the snow layer. Here, we quantify the latter, so that we can translate volume to mass change.
T. Goelles, C. E. Bøggild, and R. Greve
The Cryosphere, 9, 1845–1856, https://doi.org/10.5194/tc-9-1845-2015, https://doi.org/10.5194/tc-9-1845-2015, 2015
Short summary
Short summary
Soot (black carbon) and dust particles darken the surface of ice sheets and glaciers as they accumulate. This causes more ice to melt, which releases more particles from within the ice. This positive feedback mechanism is studied with a new two-dimensional model, mimicking the conditions of Greenland, under different climate warming scenarios. In the warmest scenario, the additional ice sheet mass loss until the year 3000 is up to 7%.
S. H. R. Rosier, G. H. Gudmundsson, and J. A. M. Green
The Cryosphere, 9, 1649–1661, https://doi.org/10.5194/tc-9-1649-2015, https://doi.org/10.5194/tc-9-1649-2015, 2015
Short summary
Short summary
We use a full-Stokes model to investigate the long period modulation of Rutford Ice Stream flow by the ocean tide. We find that using a nonlinear sliding law cannot fully explain the measurements and an additional mechanism, whereby tidally induced subglacial pressure variations are transmitted upstream from the grounding line, is also required to match the large amplitude and decay length scale of the observations.
R. Drews
The Cryosphere, 9, 1169–1181, https://doi.org/10.5194/tc-9-1169-2015, https://doi.org/10.5194/tc-9-1169-2015, 2015
Short summary
Short summary
Floating ice shelves extend the continental ice of Antarctica seawards and mediate ice-ocean interactions. Many ice shelves are incised with channels where basal melting is enhanced. With data and modeling it is shown how the channel geometry depends on basal melting and along-flow advection (also for channels which are not freely floating), and how channel formation imprints the general flow pattern. This opens up the opportunity to map the channel formation from surface velocities only.
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, https://doi.org/10.5194/tc-9-1005-2015, https://doi.org/10.5194/tc-9-1005-2015, 2015
Short summary
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.
M. Bügelmayer, D. M. Roche, and H. Renssen
The Cryosphere, 9, 821–835, https://doi.org/10.5194/tc-9-821-2015, https://doi.org/10.5194/tc-9-821-2015, 2015
A. Diez and O. Eisen
The Cryosphere, 9, 367–384, https://doi.org/10.5194/tc-9-367-2015, https://doi.org/10.5194/tc-9-367-2015, 2015
A. Diez, O. Eisen, C. Hofstede, A. Lambrecht, C. Mayer, H. Miller, D. Steinhage, T. Binder, and I. Weikusat
The Cryosphere, 9, 385–398, https://doi.org/10.5194/tc-9-385-2015, https://doi.org/10.5194/tc-9-385-2015, 2015
R. Calov, A. Robinson, M. Perrette, and A. Ganopolski
The Cryosphere, 9, 179–196, https://doi.org/10.5194/tc-9-179-2015, https://doi.org/10.5194/tc-9-179-2015, 2015
Short summary
Short summary
Ice discharge into the ocean from outlet glaciers is an important
component of mass loss of the Greenland ice sheet. Here, we present a
simple parameterization of ice discharge for coarse resolution ice
sheet models, suitable for large ensembles or long-term palaeo
simulations. This parameterization reproduces in a good approximation
the present-day ice discharge compared with estimates, and the
simulation of the present-day ice sheet elevation is considerably
improved.
V. Helm, A. Humbert, and H. Miller
The Cryosphere, 8, 1539–1559, https://doi.org/10.5194/tc-8-1539-2014, https://doi.org/10.5194/tc-8-1539-2014, 2014
A. Robinson and H. Goelzer
The Cryosphere, 8, 1419–1428, https://doi.org/10.5194/tc-8-1419-2014, https://doi.org/10.5194/tc-8-1419-2014, 2014
G. R. Leguy, X. S. Asay-Davis, and W. H. Lipscomb
The Cryosphere, 8, 1239–1259, https://doi.org/10.5194/tc-8-1239-2014, https://doi.org/10.5194/tc-8-1239-2014, 2014
A. A. Borsa, G. Moholdt, H. A. Fricker, and K. M. Brunt
The Cryosphere, 8, 345–357, https://doi.org/10.5194/tc-8-345-2014, https://doi.org/10.5194/tc-8-345-2014, 2014
I. Joughin, B. E. Smith, D. E. Shean, and D. Floricioiu
The Cryosphere, 8, 209–214, https://doi.org/10.5194/tc-8-209-2014, https://doi.org/10.5194/tc-8-209-2014, 2014
C. P. Borstad, E. Rignot, J. Mouginot, and M. P. Schodlok
The Cryosphere, 7, 1931–1947, https://doi.org/10.5194/tc-7-1931-2013, https://doi.org/10.5194/tc-7-1931-2013, 2013
V. R. Barletta, L. S. Sørensen, and R. Forsberg
The Cryosphere, 7, 1411–1432, https://doi.org/10.5194/tc-7-1411-2013, https://doi.org/10.5194/tc-7-1411-2013, 2013
I. Joughin, S. B. Das, G. E. Flowers, M. D. Behn, R. B. Alley, M. A. King, B. E. Smith, J. L. Bamber, M. R. van den Broeke, and J. H. van Angelen
The Cryosphere, 7, 1185–1192, https://doi.org/10.5194/tc-7-1185-2013, https://doi.org/10.5194/tc-7-1185-2013, 2013
A. Aschwanden, G. Aðalgeirsdóttir, and C. Khroulev
The Cryosphere, 7, 1083–1093, https://doi.org/10.5194/tc-7-1083-2013, https://doi.org/10.5194/tc-7-1083-2013, 2013
J. De Rydt, G. H. Gudmundsson, H. F. J. Corr, and P. Christoffersen
The Cryosphere, 7, 407–417, https://doi.org/10.5194/tc-7-407-2013, https://doi.org/10.5194/tc-7-407-2013, 2013
W. Leng, L. Ju, M. Gunzburger, and S. Price
The Cryosphere, 7, 19–29, https://doi.org/10.5194/tc-7-19-2013, https://doi.org/10.5194/tc-7-19-2013, 2013
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, https://doi.org/10.5194/tc-6-1561-2012, https://doi.org/10.5194/tc-6-1561-2012, 2012
S. Fujita, P. Holmlund, K. Matsuoka, H. Enomoto, K. Fukui, F. Nakazawa, S. Sugiyama, and S. Surdyk
The Cryosphere, 6, 1203–1219, https://doi.org/10.5194/tc-6-1203-2012, https://doi.org/10.5194/tc-6-1203-2012, 2012
Cited articles
Anandakrishnan, A. and Alley, R. B.: Tidal forcing of basal seismicity of ice
stream C, West Antarctica, observed far inland, J. Geophys. Res., 102,
15183–15196, 1997.
Benn, D., Gulley, J., Luckman, A., Adamek, A., and Glowacki, P.: Englacial
drainage system formed by hydrologically driven crevasse propagation, J.
Glaciol., 55, 513–523, 2009.
Bindschadler, R. A.: Jakobshavns Glacier drainage basin: a balance
assessment, J. Geophys. Res., 89, 2066–2072, 1984.
Blatter, H.: Velocity and stress fields in grounded glaciers: a simple
algorithm for including deviatoric stress gradients, J. Glaciol., 41,
333–344, 1995.
Blatter, H., Greve, R., and Abe-Ouchi, A.: Present State and Prospects of Ice
Sheet and Glacier Modelling, Surv. Geophys., Springer, New York, 2011.
Bougamont, M., Price, S., Christoffersen, P., and Payne, A. J.: Dynamic
patterns of ice stream flow in a 3-D higher-order ice sheet model with
plastic bed and simplified hydrology, J. Geophys. Res., 116, F04018,
https://doi.org/10.1029/2011JF002025,
2011.
Brecher, H. H.: Photogrammetric determination of surface velocities and
elevations on Byrd Glacier, Antarct. J. US, 17, 79–81, 1982.
Budd, W. F., Jensen, D., and Radok, U.: Derived Physical Characteristics of
the Antarctic Ice Sheet, Meteorology Department Australian National Antarctic
Research Expeditions (ANARE) Interim Reports, Series A (IV), Glaciology 120,
University of Melbourne, Melbourne, 1971.
Bueler, E. and Brown, J.: Shallow shelf approximation as a “sliding law” in
a thermomechanically coupled ice sheet model, J. Geophys. Res., 114, F03008,
https://doi.org/10.1029/2008JF001179,
2009.
Carbonnell, M. and Bauer, A.: Exploitation des couvertures photographiques
aériennes répétées du front des glaciers vêlant dans
Diske Bugt en Umanak Fjord, Juin-Juillet, 1964, Meddelelser om Groenland,
173, 1–78, 1968.
Carlson, A. E., Jenson, J. W., and Clark, P. U.: Modeling the subglacial
hydrology of the James Lobe of the Laurentide Ice Sheet, Quaternary Sci.
Rev., 26, 1384–1397, 2007.
Clark, P. U.: Surface form of the southern Laurentide Ice Sheet and its
implications to ice-sheet dynamics, Geol. Soc. Am. Bull., 104, 595–605,
1992.
Cook, A. C., Vel, S. S., Gerbi, C., and Johnson, S. E.: Computational
analysis of nonlinear creep of polyphase aggregates: influence of phase
morphology, J. Geophys. Res., 119, 29 pp.,
https://doi.org/10.1002/2014JB011197,
2014.
Denton, G. H. and Hughes, T. J. (Eds.): The Last Great Ice Sheets,
Wiley-Interscience, New York, 1981.
Denton, G. H., Hughes, T. J., and Karlen, W.: Global ice-sheet system
interlocked by sea level, Quat. Res., 26, 3–26, 1986.
Drewry, D. J. (Ed.): Antarctica: Glaciological and Geophysical Folio, Scott
Polar Research Institute, University of Cambridge, Cambridge, 1983.
Dupont, T. and Alley, R. B.: Assessment of the importance of ice-shelf
buttressing to ice-sheet flow, Geophys. Res. Lett., 32, L04503,
https://doi.org/10.1029/2004GL022024,
2005.
Dupont, T. and Alley, R. B.: Role of small ice shelves in sea-level rise,
Geophys. Res. Lett., 33, L09503,
https://doi.org/10.1029/2005GL025665,
2006.
Echelmeyer, K., Clarke, T. S., and Harrison, W. D.: Surficial glaciology of
Jakobshavns Isbræ, West Greenland: Part I. Surface morphology,
J. Glaciol., 37, 368–382, 1991.
Echelmeyer, K., Harrison, W. D., Clarke, T. S., and Benson, C.: Surficial
glaciology of Jakobshavns Isbræ, West Greenland: Part II. Ablation,
accumulation and temperature, J. Glaciol., 38, 169–181, 1992.
Engelhardt, H. and Kamb, B.: Ice stream flow history and surge potential,
Ann. Glaciol., 54, 287–298, 2013.
Fastook, J. L. and Hughes, T. J.: New perspectives on paleoglaciology,
Quaternary Sci. Rev., 80, 169–194, 2013.
Fastook, J. L. and Prentice, M.: A finite-element model of Antarctica;
sensitivity test for meteorological mass-balance relationship, J. Glaciol.,
40, 167–175, 1994.
Fastook, J. L., Brecher, H. H., and Hughes, T. J.: Derived bedrock
elevations, strain rates, and stresses from measured surface elevations and
velocities: Jakobshavn Glacier, Greenland, J. Glaciol., 41, 161–173, 1995.
Fricker, H. A. and Scambos, T.: Connected subglacial lake activity on lower
Mercer and Whillans Ice Streams, 2003–2008, J. Glaciol., 55, 303–315, 2009.
Funk, M., Echelmeyer, K., and Iken, A.: Mechanisms of fast flow in
Jakobshavns Isbrae, West Greenland: Part II – Modeling of englacial
temperatures, J. Glaciol., 40, 569–585, 1994.
Gagliardini, O., Durand, G., Zwinger, T., Hindmarsh, R. C. A., and Le
Meur, E.: Coupling of ice-sheet melting and buttressing is a key process in
ice-sheet dynamics, Geophys. Res. Lett., 37, L14501
https://doi.org/10.1029/2010GL043334,
2010.
Gerbi, C., Johnson, S. E., Cook, A., and Senthil, S. V.: Effect of phase
morphology on bulk strength for power-law materials, Geophys. J. Int., 200,
374–389, 2015.
Glen, J. W.: The Flow Law of Ice, Int. Assoc. Scient. Hydrol., 47, 171–183,
1858.
Gogineni, S., Yan, J.-B., Paden, J., Leuschen, C., Li, J.,
Rodrigues-Morales, F., Braaten, D., Purdon, K., Wang, Z., Liu, W., and
Gauch, J.: Bed topography of Jakobshavn Isbrae, Greenland, and Byrd Glacier,
Antarctica, J. Glaciol., 60, 813–833,
https://doi.org/10.3189/2014JoG14J129,
2014.
Gow, A. J., Meese, D. A., Alley, R. B., Fitzpatrick, J. J.,
Anandakrishnan, S., Woods, G. A., and Elder, B. C.: Physical and structural
properties of the Greenland Ice Sheet Project 2 ice cores: a review,
J. Geophys. Res., 102, 26559–26575, 1997.
Greve, R.: A continuum-mechanical formulation for shallow polythermal ice
sheets, Philos. T. Roy. Soc. A, 355, 921–974,
https://doi.org/10.1098/rsta.1997.0050,
1997.
Hofstede, C. and Hughes, T.: Can ice sheets self-destruct and cause rapid
climate change? A case study: Jakobshavn Isbrae, Greenland, in: Horizons in
Earth Sciences, Vol. 11, chapter 4, edited by: Veress, B. and Szigethy, J.,
Nova Science Publishers, Inc., Hauppauge, NY, 2014.
Holland, D. R., Thomas, R., Young, B. de, Ribergaard, M., and Lyberth, B.:
Acceleration of Jakobshavn Isbrae triggered by warm subsurface ocean waters,
Nat. Geosci., 1, 659–664,
https://doi.org/10.1038/ngeo316, 2008.
Hooke, R. LeB., Holmlund, P., and Iverson, N. R.: Extrusion flow demonstrated
by bore-hole deformation measurements over a riegel, Shorglaciaren, Sweden,
J. Glaciol., 33), 72–78, 1987.
Hughes, T.: Ice Streamline Cooperative Antarctic Project, ISCAP Bulletin
No. 1: Scientific Justification, Institute of Polar Studies, The Ohio State
University, Columbus, Ohio, 1972.
Hughes, T.: Is the West Antarctic Ice Sheet disintegrating?, J. Geophys.
Res., 78, 7884–7910, 1973.
Hughes, T.: A differential ablation-longitudinal compression mechanism for
generating wave trains on cold alpine glaciers, in: IASH – AISH Publication
Number 104, Snow and Ice Symposium – Neiges et Glaces, Proceedings of the
Moscow Symposium, August 1971, Actes du Colloque de Moscou, aout 1971 Moscou,
1975.
Hughes, T.: West Antarctic ice streams, Rev. Geophys. Space Ge., 15, 1–46,
https://doi.org/10.1029/RG015i001p00001,
1977.
Hughes, T.: Numerical Reconstruction of Paleo-Ice Sheets, in: The Last Great
Ice Sheets, edited by: Denton, G. H. and Hughes, T. J., Wiley-Interscience,
New York, 221–261, 1981.
Hughes, T.: On the disintegration of ice shelves: the role of thinning, Ann.
Glaciol., 3, 146–151, 1982.
Hughes, T.: On the disintegration of ice shelves: the role of fracture,
J. Glaciol., 29, 98–117, 1983.
Hughes, T.: The Jakobshavns effect, Geophys. Res. Lett., 13, 46–48, 1986.
Hughes, T.: Deluge II and the continent of doom: rising sea level and
collapsing Antarctic ice, Boreas, 16, 89–100, 1987.
Hughes, T.: On the pulling power of ice streams, J. Glaciol., 38, 125–151,
1992.
Hughes, T.: Ice Sheets, Oxford University Press, New York, 1998.
Hughes, T.: The geometrical force balance in glaciology, J. Geophys. Res.,
108, 2526,
https://doi.org/10.1029/2003JB002557,
2003.
Hughes, T.: Variations of ice-bed coupling, beneath and beyond ice streams:
the force balance, J. Geophys. Res., 114, B01410,
https://doi.org/10.1029/2008JB005714,
2009a.
Hughes, T.: Correction to “Variations of ice-bed coupling beneath and beyond
ice streams: the force balance”, J. Geophys. Res., 114, B04499,
https://doi.org/10.1029/2009JB006426,
2009b.
Hughes, T.: A simple holistic hypothesis for the self-destruction of ice
sheets, Quaternary Sci. Rev., 30, 1829–1845, 2011.
Hughes, T.: Holistic Ice Sheet Modeling: a First-Order Approach, Nova Science
Publishers, Inc., Hauppauge, New York, 2012.
Hughes, T. J. and Fastook, J. L.: Byrd Glacier: 1978–1979 field results,
Antarct. J. US, 16, 86–89, 1981.
Hughes, T., Sargent, A., and Fastook, J.: Ice-bed coupling beneath and beyond
ice streams: Byrd Glacier, Antarctica, J. Geophys. Res., 116, 1–17, 2011.
Hulbe, C. L. and Fahnestock, M. A.: West Antarctic ice stream discharge
variability: mechanism, controls, and pattern of grounding line retreat,
J. Glaciol., 50, 471–484, 2004.
Iken, A.: The effect of subglacial water pressure on the sliding velocity of
a glacier in an idealized numerical model, J. Glaciol., 27, 407–422, 1981.
Iken, A. and Bindschadler, R. A.: Combined measurements of subglacial water
pressure and surface velocity of Findelengletscher, Switzerland: conclusions
about drainage system and sliding mechanism, J. Glaciol., 32, 101–119, 1986.
Iken, A., Echelmeyer, K., Harrison, W., and Funk, M.: Mechanics of fast flow
in Jakobshavns Isbrae, West Greenland: Part I. Measurements of temperature
and water level in deep boreholes, J. Glaciol., 39, 15–25, 1993.
Jenson, J. W., Clark, P. U., MacAyeal, D. R., Ho, C. L., and Vela, J. C.:
Numerical modeling of advective transport of saturated deforming sediment
beneath the Lake Michigan Lobe, Laurentide Ice Sheet, Geomorphology, 14,
157–166, 1995.
Jenson, J. W., MacAyeal, D. R., Clark, P. U., Ho, C. L., and Vela, J. C.:
Numerical modeling of subglacial sediment deformation: implications for the
behavior of the Lake Michigan Lobe, Laurentide Ice Sheet, J. Geophys. Res.,
101, 8717–8728, 1996.
Joughin, I., Smith, B. E., Shean, D. E., and Floricioiu, D.: Brief
Communication: Further summer speedup of Jakobshavn Isbræ, The
Cryosphere, 8, 209–214,
https://doi.org/10.5194/tc-8-209-2014,
2014.
Joughin, I. R., Howat, I. M., Fahnestock, M. A., Smith, B., Krabill, W. B.,
Alley, R. B., Stern, H., and Truffer, M.: Continued evolution of Jakobshavn
Isbrae following its rapid speedup, J. Geophys. Res., 113, F04006,
https://doi.org/10.1029/2008JF001023,
2008.
Kamb, B.: Basal zone of the West Antarctic ice streams and its role in
lubrication of their rapid motion, in: The West Antarctic Ice Sheet: Behavior
and Environment, edited by: Alley, R. B. and Bindschadler, R. A., Antarctic
Research Series, American Geophysical Union, Washington, D.C., 157–200,
2001.
Kenneally, J. P. and Hughes, T.: Calving giant icebergs: old principles, new
applications, Antarct. Sci., 18, 409–419, 2006.
Larour, E., Setousi, H., Morlighem, M., and Rignot, E.: Continental scale,
high order, high spatial resolution, ice sheet modeling using the Ice Sheet
System Model (ISSM), J. Geophys. Res., 117, F01022,
https://doi.org/10.1029/2011JF002140,
2012.
Lliboutry, L.: General theory of subglacial cavitation and sliding of
temperate glaciers, J. Glaciol., 7, 21–58, 1968.
Lüthi, M., Funk, M., Iken, A., Gogineni, S. P., and Truffer, M.:
Mechanism of fast flow in Jakobshavns Isbrae, West Greenland.
Part III. Measurements of ice deformationm, temperpature and cross-borehole
conductivity in boreholes to the bedrock, J. Glaciol., 48, 369–385, 2002.
MacAyeal, D. R.: Large-scale ice flow over a viscous basal sediment: Theory
and application to Ice Stream B, Antarctica, J. Geophys. Res., 94,
4071–4087, 1989.
Nye, J. F.: The mechanics of glacier flow, J. Glaciol., 2, 82–93, 1952.
Paterson, W. S. B.: The Physics of Glaciers, 3rd Edn., Butterworth-Heineman,
Oxford, 481 pp., 1994.
Pattyn, F.: A new three-dimensional higher-order thermomechanical ice sheet
model: basic sensitivity, ice stream development, and ice flow across
subglacial lakes, J. Geophys. Res., 108, 2382,
https://doi.org/10.1029/2002JB002329,
2003.
Pelto, M. S., Hughes, T. J., and Brecher, H. H.: Equilibrium state of
Jakobshavns Isbrae, West Greenland, Ann. Glaciol., 12, 127–131, 1989.
Pfeffer, W. T. and Bretherton, C. S.: The effect of crevasses on the solar
heating of a glacier surface, in: IASH Publiction No. 170, The Physical Basis
of Ice Sheet Modeling, Proceeedings of the Vancouver Symposium, August 1987,
Vancouver, 191–205, 1987.
Pfeffer, W. T., Harper, J. T., and O'Neel, S.: Kinematic constraints on
glacier contributions to 21st Century sea-level rise, Science, 321,
1340–1343, 2008.
Pingree, K., Lurie, M., and Hughes, T.: Is the East Antarctic Ice Sheet
stable?, Quaternary Res., 75, 417–429, 2011.
Pollard, D. and DeConto, R. M.: Description of a hybrid ice sheet-shelf
model, and application to Antarctica, Geosci. Model Dev., 5, 1273–1295,
https://doi.org/10.5194/gmd-5-1273-2012,
2012.
Prescott, P. R., Kenneally, J. P., and Hughes, T. J.: Relating crevassing to
nonlinear strain in the floating part of Jakobshavns Isbrae, West Greenland,
Ann. Glaciol., 36, 149–156, 2003.
Pritchard, H. D., Arthern, D. G., Vaughan, D. G., and Edwards, L. A.:
Extensie dynamic thinning on the margins of the Greenland and Antarctic ice
sheets, Nature, 461, 803–806,
https://doi.org/10.1038/Nature08471, 2009.
Rathbun, A. P., Marone, C., Alley, R. B., and Anandakrishnan, S.: Laboratory
study of the frictional rheology of sheared till, J. Geophys. Res., 113,
F02020,
https://doi.org/10.1029/2007JF000815,
2008.
Reeh, N.: A plasticity approach to the steady-state shape of a
three-dimensional ice sheet, J. Glaciol., 7, 215–232, 1982.
Reeh, N.: Reconstruction of the glacial ice covers of Greenland and the
Canadian Arctic islands by three-dimensional, perfectly plastic ice-sheet
modeling, Ann. Glaciol., 5, 115–121, 1984.
Reusch, D. and Hughes, T. J.: Surfaxe “waves” on Byrd Glacier, Antarct.
Sci., 15, 547–555,
https://doi.org/10.1017/S0954102003001664,
2003.
Rignot, E. and Kanagaratnam, P.: Changes in the velocity structure of the
Greenland Ice Sheet, Science, 311, 986–990, 2006.
Rignot, E., Casassa, G., Gogineni, P., Krabill, W., Rivera, A., and
Thomas, R.: Accelerated ice discharge from the Antarctic Peninsula following
the collapse of Larsen B ice shelf, Geophys. Res. Lett., 31, L18401,
https://doi.org/10.1029/2004GL020697,
2004.
Rignot, E., Mouginet, J., and Scheuchl, B.: NASA research yields field map of
Antarctic ice flow, NASA News, available at:
www.jpl.nasa.gov/news/news.php?release=2011-256 (last access:
August 2015), 2011a.
Rignot, E., Mouginot, J., and Scheuchl, B.: Ice flow of the Antarctic Ice
Sheet, Science, 333, 1427–1430, 2011b.
Rowden-Rich, R. J. M. and Wilson, C. J. L.: Models for strain localization in
Law Dome, East Antarctica, Ann. Glaciol., 23, 396–401, 1996.
Saito, F. and Abe-Ouchi, A.: Sensitivity of Greenland ice sheet simulation to
the numerical procedure employed for ice-sheet dynamics, Ann. Glaciol., 42,
331–336,
https://doi.org/10.3189/172756405781813069,
2005.
Sanderson, T. J. O.: Equilibrium profile of ice shelves, J. Glaciol., 22,
435–460, 1979.
Sane, S. M., Desai, C. S., Jenson, J. W., Contractor, D. N., Carlson, A. E.,
and Clark, P. U.: Disturbed state constitutive modeling of two Pleistocene
tills, Quaternary Sci. Rev., 27, 267–283, 2008.
Sargent, A.: Modeling Ice Streams, PhD thesis, University of Maine, Orono,
106 pp., 2009.
Sargent, A. and Fastook, J. L.: Manufactured analytical solutions for
isothermal full-Stokes ice sheet models, The Cryosphere, 4, 285–311,
https://doi.org/10.5194/tc-4-285-2010,
2010.
Scambos, T. A., Bohlander, J. A., Shuman, A., and Skvarca. P.: Glacier
acceleration and thinning after ice shelf collapse in the Larsen B embayment,
Antarctica, Geophys. Res. Lett., 31, L18402l,
https://doi.org/10.1029/2004GL020670,
2004.
Schoof, C.: Marine ice-sheet dynamics. Part 1. The case of rapid sliding,
J. Fluid Mech., 573, 27–55, 2007.
Schoof, C.: Ice-sheet acceleration driven by melt supply variability, Nature,
468, 803–806, 2010.
Schoof, C. and Hindmarsh, R. C. A.: Thin-film flows with wall slip: an
asymptotic analsis of higher order glacier flow models, Q. J. Mech. Appl.
Math., 63, 73–114,
https://doi.org/10.1093/qjmam/hbp025,
2010.
Schulson, E. M. and Duval, P.: Creep and Fracture of Ice, Cambridge
University Press, Cambridge, UK, 401 pp., 2009.
Scofield, J. P., Fastook, J. L., and Hughes, T. J.: Evidence for a frozen
bed, Byrd Glacier, Antarctica, J. Geophys. Res., 96, 11649–11655,
https://doi.org/10.1029/91JB00839, 1991.
Seddik, H., Greve, R., Zwinger, T., Gillet-Chaulet, F., and Gagliardini, O.:
Simulations of the Greenland Ice Sheet 100 years into the future with the
full Stokes model Elmer/Ice, J. Glaciol., 58, 427–440,
https://doi.org/10.3189/2012JoG11J177,
2012.
Siegert, M. J.: Comments on “Calculating basal thermal zones beneath the
Antarctic Ice Sheet” by Wilch and Hughes, J. Glaciol., 46, 159–160, 2001.
Smith, B. E., Fricker, H. A., Joughin, I. R., and Tulaczyk, S.: An inventory
of active subglacial lakes in Antarctica detected by ICESat (2003–2008),
J. Glaciol., 55, 573–595, 2009.
Stearns, L. A., Smith, B. E., and Hamilton, G. S.: Increased flow speed on a
large East Antarctic outlet glacier due to subglacial floods, Nat. Geosci.,
1, 827–831, 2008.
Swithinbank, C. W.: Ice movement of valley glaciers flowing into the Ross Ice
Shelf, Antarctica, Science, 141, 523–524, 1963.
Thomas, R. H.: The creep of ice shelves: theory, J. Glaciol., 12, 45–53,
1973a.
Thomas, R. H.: The creep of ice shelves: interpretation of observed
behaviour, J. Glaciol., 12, 55–70, 1973b.
Thomas, R. H.: Force-perturbation analysis of recent thinning and
acceleration of Jakobshavns Isbrae, Greenland, J. Glaciol., 50, 57–66, 2004.
Thomas, R. H. and MacAyeal, D. R.: Derived characteristics of the Ross Ice
Shelf, J. Glaciol., 28, 397–412, 1982.
Thomas, R. H., Rignot, E. J., Kanagaratnam, P., Krabill, W. B., and
Casassa, G.: Force-perturbation analysis of Pine Island Glacier, Antarctica,
suggests cause for recent acceleration, Ann. Glaciol., 39, 133–138, 2004.
Van der Veen, C. J.: A note on the equilibrium profile of a free floating ice
shelf, The Netherlands, Institut voor Meteorologie en Oceanografie,
Rijksuniversiteit-Utrecht, Utrecht, 1–15, 1983.
Van der Veen, C. J.: Fracture mechanics approach to penetration of surface
crevasses on glaciers, Cold Reg. Sci. Technol., 27, 31–47, 1998a.
Van der Veen, C. J.: Fracture mechanics approach to penetration of bottom
crevasses on glaciers, Cold Reg. Sci. Technol., 27 213–223, 1998b.
Van der Veen, C. J.: Fundamentals of Glacier Dynamics, A. A. Balkema,
Rotterdam, 462 pp., 1999.
Van der Veen, C. J., Stearns, L. A., Johnson, J., and Csatho, B.: Flow
dynamics of Byrd Glacier, East Antarctica, J. Glaciol., 60,
https://doi.org/10.3189/2014JoG14J052,
2014.
Weertman, J.: On the sliding of glaciers, J. Glaciol., 3, 33–38, 1957a.
Weertman, J.: Deformation of floating ice shelves, J. Glaciol., 3, 38–42,
1957b.
Weertman, J.: Stability of the junction of an ice sheet and an ice shelf,
J. Glaciol., 13, 3–11, 1974.
Weideck, A. and Bennike, O.: Quaternary Glaciation History and Glaciology of
Jakobshavn Isbrae and the Disko Bugt Region, West Greenland: a Review,
Ministry of Climate and Energy, Copenhagen, Denmark, 2007.
Whillans, I. M., Chen, Y. H., Van der Veen, C. J., and Hughes, T.: Force
Budget III: application to three-dimensional flow of Byrd Glacier,
Antarctica, J. Glaciol., 35, 68–80, 1989.
Wilch, E. and Hughes, T.: Mapping basal thermal zones beneath the Antarctic
ice sheet, J. Glaciol., 46, 297–310, 2000.
Zhao, Z.: Measurement, analysis, and modeling deformation of the shelf-flow,
Byrd Glacier, PhD thesis, University of Maine, Orono, 108 pp., 1990.
Zwally, H. J., Abdalati, W., Herring, T., Larson, K., Savba, J., and
Steffen, K.: Surface melt-induced acceleration of Greenland Ice-Sheet flow,
Science, 297, 218–222, 2002.
Short summary
The Antarctic and Greenland ice sheets are drained primarily by fast ice streams that end as ice shelves if they become afloat. Smooth transitions from slow sheet flow to fast stream flow to confined shelf flow are obtained and applied to Byrd Glacier in Antarctica after two upstream subglacial lakes suddenly drained in 2006, and to Jakobshavn Isbrae in Greenland after a confined ice shelf suddenly disintegrated in 2002. Byrd Glacier quickly stabilized, but Jakobshavn Isbrae remains unstable.
The Antarctic and Greenland ice sheets are drained primarily by fast ice streams that end as ice...
