Articles | Volume 9, issue 6
https://doi.org/10.5194/tc-9-2183-2015
© Author(s) 2015. 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-9-2183-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
20 Nov 2015
Research article |
| 20 Nov 2015
A new methodology to simulate subglacial deformation of water-saturated granular material
A. Damsgaard
CORRESPONDING AUTHOR
Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
D. L. Egholm
Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
J. A. Piotrowski
Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
S. Tulaczyk
Department of Earth and Planetary Sciences, University of California, Santa Cruz, California 95064, USA
N. K. Larsen
Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, 1350 Copenhagen K, Denmark
C. F. Brædstrup
Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
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Niels J. Korsgaard, Kristian Svennevig, Anne S. Søndergaard, Gregor Luetzenburg, Mimmi Oksman, and Nicolaj K. Larsen
Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2023-32, https://doi.org/10.5194/nhess-2023-32, 2023
Preprint under review for NHESS
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A tsunami wave will leave evidence of erosion and deposition in coastal lakes, making it possible to determine the run-up height and when it occurred. Here, we use six lakes today located at elevations 19–134 m. a.s.l. close to the settlement of Saqqaq, West Greenland, to show that at least two giant tsunamis occurred 7300–7600 years ago with run-up heights larger than 40 m. We infer, that any tsunamis from at least nine giga-scale landslides must have happened 8500–10000 years ago.
Ricardo Garza-Giron and Slawek M. Tulaczyk
The Cryosphere Discuss., https://doi.org/10.5194/tc-2023-44, https://doi.org/10.5194/tc-2023-44, 2023
Preprint under review for TC
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By analyzing temperature time series over more than 20 years, we have found a discrepancy between the 2-meter temperature values reported by the ERA5 reanalysis and the Automatic Weather Stations in the McMurdo Sound, Antarctica. The ERA5 reanalysis temperatures are systematically colder by ~5 °C.
Hilary A. Dugan, Peter T. Doran, Denys Grombacher, Esben Auken, Thue Bording, Nikolaj Foged, Neil Foley, Jill Mikucki, Ross A. Virginia, and Slawek Tulaczyk
The Cryosphere, 16, 4977–4983, https://doi.org/10.5194/tc-16-4977-2022, https://doi.org/10.5194/tc-16-4977-2022, 2022
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In the McMurdo Dry Valleys of Antarctica, a deep groundwater system has been hypothesized to connect Don Juan Pond and Lake Vanda, both surface waterbodies that contain very high concentrations of salt. This is unusual, since permafrost in polar landscapes is thought to prevent subsurface hydrologic connectivity. We show results from an airborne geophysical survey that reveals widespread unfrozen brine in Wright Valley and points to the potential for deep valley-wide brine conduits.
Sarah U. Neuhaus, Slawek M. Tulaczyk, Nathan D. Stansell, Jason J. Coenen, Reed P. Scherer, Jill A. Mikucki, and Ross D. Powell
The Cryosphere, 15, 4655–4673, https://doi.org/10.5194/tc-15-4655-2021, https://doi.org/10.5194/tc-15-4655-2021, 2021
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We estimate the timing of post-LGM grounding line retreat and readvance in the Ross Sea sector of Antarctica. Our analyses indicate that the grounding line retreated over our field sites within the past 5000 years (coinciding with a warming climate) and readvanced roughly 1000 years ago (coinciding with a cooling climate). Based on these results, we propose that the Siple Coast grounding line motions in the middle to late Holocene were driven by relatively modest changes in regional climate.
Tun Jan Young, Carlos Martín, Poul Christoffersen, Dustin M. Schroeder, Slawek M. Tulaczyk, and Eliza J. Dawson
The Cryosphere, 15, 4117–4133, https://doi.org/10.5194/tc-15-4117-2021, https://doi.org/10.5194/tc-15-4117-2021, 2021
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If the molecules that make up ice are oriented in specific ways, the ice becomes softer and enhances flow. We use radar to measure the orientation of ice molecules in the top 1400 m of the Western Antarctic Ice Sheet Divide. Our results match those from an ice core extracted 10 years ago and conclude that the ice flow has not changed direction for the last 6700 years. Our methods are straightforward and accurate and can be applied in places across ice sheets unsuitable for ice coring.
Krista F. Myers, Peter T. Doran, Slawek M. Tulaczyk, Neil T. Foley, Thue S. Bording, Esben Auken, Hilary A. Dugan, Jill A. Mikucki, Nikolaj Foged, Denys Grombacher, and Ross A. Virginia
The Cryosphere, 15, 3577–3593, https://doi.org/10.5194/tc-15-3577-2021, https://doi.org/10.5194/tc-15-3577-2021, 2021
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Lake Fryxell, Antarctica, has undergone hundreds of meters of change in recent geologic history. However, there is disagreement on when lake levels were higher and by how much. This study uses resistivity data to map the subsurface conditions (frozen versus unfrozen ground) to map ancient shorelines. Our models indicate that Lake Fryxell was up to 60 m higher just 1500 to 4000 years ago. This amount of lake level change shows how sensitive these systems are to small changes in temperature.
Svend Funder, Anita H. L. Sørensen, Nicolaj K. Larsen, Anders A. Bjørk, Jason P. Briner, Jesper Olsen, Anders Schomacker, Laura B. Levy, and Kurt H. Kjær
Clim. Past, 17, 587–601, https://doi.org/10.5194/cp-17-587-2021, https://doi.org/10.5194/cp-17-587-2021, 2021
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Cosmogenic 10Be exposure dates from outlying islets along 300 km of the SW Greenland coast indicate that, although affected by inherited 10Be, the ice margin here was retreating during the Younger Dryas. These results seem to be corroborated by recent studies elsewhere in Greenland. The apparent mismatch between temperatures and ice margin behaviour may be explained by the advection of warm water to the ice margin on the shelf and by increased seasonality, both caused by a weakened AMOC.
Slawek M. Tulaczyk and Neil T. Foley
The Cryosphere, 14, 4495–4506, https://doi.org/10.5194/tc-14-4495-2020, https://doi.org/10.5194/tc-14-4495-2020, 2020
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Much of what we know about materials hidden beneath glaciers and ice sheets on Earth has been interpreted using radar reflection from the ice base. A common assumption is that electrical conductivity of the sub-ice materials does not influence the reflection strength and that the latter is controlled only by permittivity, which depends on the fraction of water in these materials. Here we argue that sub-ice electrical conductivity should be generally considered when interpreting radar records.
Maxime Bernard, Philippe Steer, Kerry Gallagher, and David Lundbek Egholm
Earth Surf. Dynam., 8, 931–953, https://doi.org/10.5194/esurf-8-931-2020, https://doi.org/10.5194/esurf-8-931-2020, 2020
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Detrital thermochronometric age distributions of frontal moraines have the potential to retrieve ice erosion patterns. However, modelling erosion and sediment transport by the Tiedemann Glacier ice shows that ice velocity, the source of sediment, and ice flow patterns affect age distribution shape by delaying sediment transfer. Local sampling of frontal moraine can represent only a limited part of the catchment area and thus lead to a biased estimation of the spatial distribution of erosion.
Anne Sofie Søndergaard, Nicolaj Krog Larsen, Olivia Steinemann, Jesper Olsen, Svend Funder, David Lundbek Egholm, and Kurt Henrik Kjær
Clim. Past, 16, 1999–2015, https://doi.org/10.5194/cp-16-1999-2020, https://doi.org/10.5194/cp-16-1999-2020, 2020
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We present new results that show how the north Greenland Ice Sheet responded to climate changes over the last 11 700 years. We find that the ice sheet was very sensitive to past climate changes. Combining our findings with recently published studies reveals distinct differences in sensitivity to past climate changes between northwest and north Greenland. This highlights the sensitivity to past and possible future climate changes of two of the most vulnerable areas of the Greenland Ice Sheet.
Sarah U. Neuhaus, Slawek M. Tulaczyk, and Carolyn Branecky Begeman
The Cryosphere, 13, 1785–1799, https://doi.org/10.5194/tc-13-1785-2019, https://doi.org/10.5194/tc-13-1785-2019, 2019
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Relatively few studies have been carried out on icebergs inside fjords, despite the fact that the majority of recent sea level rise has resulted from glaciers terminating in fjords. We examine the size and spatial distribution of icebergs in Columbia Fjord, Alaska, over a period of 8 months to determine their influence on fjord dynamics.
Brent C. Christner, Heather F. Lavender, Christina L. Davis, Erin E. Oliver, Sarah U. Neuhaus, Krista F. Myers, Birgit Hagedorn, Slawek M. Tulaczyk, Peter T. Doran, and William C. Stone
The Cryosphere, 12, 3653–3669, https://doi.org/10.5194/tc-12-3653-2018, https://doi.org/10.5194/tc-12-3653-2018, 2018
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Solar radiation that penetrates into the glacier heats the ice to produce nutrient-containing meltwater and provides light that fuels an ecosystem within the ice. Our analysis documents a near-surface photic zone in a glacier that functions as a liquid water oasis in the ice over half the annual cycle. Since microbial growth on glacier surfaces reduces the amount of solar radiation reflected, microbial processes at depths below the surface may also darken ice and accelerate meltwater production.
Jacob C. Yde, Niels T. Knudsen, Jørgen P. Steffensen, Jonathan L. Carrivick, Bent Hasholt, Thomas Ingeman-Nielsen, Christian Kronborg, Nicolaj K. Larsen, Sebastian H. Mernild, Hans Oerter, David H. Roberts, and Andrew J. Russell
Hydrol. Earth Syst. Sci., 20, 1197–1210, https://doi.org/10.5194/hess-20-1197-2016, https://doi.org/10.5194/hess-20-1197-2016, 2016
C. F. Brædstrup, D. L. Egholm, S. V. Ugelvig, and V. K. Pedersen
Earth Surf. Dynam., 4, 159–174, https://doi.org/10.5194/esurf-4-159-2016, https://doi.org/10.5194/esurf-4-159-2016, 2016
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When studying long-term glacial landscape evolution one must make simplifying assumptions about the nature of glacial flow. In this study we show that for two different numerical models such simplifications are mostly unimportant in the setting of glacial landscape evolution. Following this we find that glacial erosion is most intense in the early stages of glaciation and its effects are reduced with time due to flow patterns in the ice removing areas of highest resistance to flow.
J. L. Andersen, D. L. Egholm, M. F. Knudsen, J. D. Jansen, and S. B. Nielsen
Earth Surf. Dynam., 3, 447–462, https://doi.org/10.5194/esurf-3-447-2015, https://doi.org/10.5194/esurf-3-447-2015, 2015
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An increasing number of studies demonstrates links between the intensity of periglacial processes and bedrock erosion in steep mountain landscapes. Here, we quantify the dependence of periglacial processes on temperature and sediment thickness. This allows us to model frost processes across the full range of settings encountered in mountain landscapes. We find that sediment mantle thickness strongly modulates the relation between climate and periglacial weathering and sediment transport.
D. L. Egholm, J. L. Andersen, M. F. Knudsen, J. D. Jansen, and S. B. Nielsen
Earth Surf. Dynam., 3, 463–482, https://doi.org/10.5194/esurf-3-463-2015, https://doi.org/10.5194/esurf-3-463-2015, 2015
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We incorporate relations between climate, sediment thickness and periglacial processes quantified in the accompanying paper into a landscape evolution model. This allows us to time-integrate the periglacial contribution to mountain topography on million-year time scales. It is a robust result of our simulations that periglacial processes lead to topographic smoothing. Owing to the climate dependency, this smoothing leads to formation of low-relief surfaces at altitudes controlled by temperature.
Related subject area
Subglacial Processes
Compensating errors in inversions for subglacial bed roughness: same steady state, different dynamic response
Channelized, distributed, and disconnected: spatial structure and temporal evolution of the subglacial drainage under a valley glacier in the Yukon
Towards modelling of corrugation ridges at ice-sheet grounding lines
Drainage and refill of an Antarctic Peninsula subglacial lake reveal an active subglacial hydrological network
Persistent, extensive channelized drainage modeled beneath Thwaites Glacier, West Antarctica
Filling and drainage of a subglacial lake beneath the Flade Isblink ice cap, northeast Greenland
Radar sounding survey over Devon Ice Cap indicates the potential for a diverse hypersaline subglacial hydrological environment
Long-period variability in ice-dammed glacier outburst floods due to evolving catchment geometry
Seasonal evolution of basal environment conditions of Russell sector, West Greenland, inverted from satellite observation of surface flow
Grounding zone subglacial properties from calibrated active-source seismic methods
Subglacial carbonate deposits as a potential proxy for a glacier's former presence
Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica
Subglacial lakes and hydrology across the Ellsworth Subglacial Highlands, West Antarctica
The role of electrical conductivity in radar wave reflection from glacier beds
Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard
Review article: Geothermal heat flow in Antarctica: current and future directions
Quantification of seasonal and diurnal dynamics of subglacial channels using seismic observations on an Alpine glacier
Exceptionally high heat flux needed to sustain the Northeast Greenland Ice Stream
Glaciohydraulic seismic tremors on an Alpine glacier
Subglacial roughness of the Greenland Ice Sheet: relationship with contemporary ice velocity and geology
Airborne radionuclides and heavy metals in high Arctic terrestrial environment as the indicators of sources and transfers of contamination
Subglacial hydrological control on flow of an Antarctic Peninsula palaeo-ice stream
Pervasive cold ice within a temperate glacier – implications for glacier thermal regimes, sediment transport and foreland geomorphology
Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet, Greenland Ice Sheet
Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica
Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream
Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming
Brief Communication: Twelve-year cyclic surging episodes at Donjek Glacier in Yukon, Canada
Tremor during ice-stream stick slip
Transition of flow regime along a marine-terminating outlet glacier in East Antarctica
Boundary conditions of an active West Antarctic subglacial lake: implications for storage of water beneath the ice sheet
A balanced water layer concept for subglacial hydrology in large-scale ice sheet models
The "tipping" temperature within Subglacial Lake Ellsworth, West Antarctica and its implications for lake access
Interaction between ice sheet dynamics and subglacial lake circulation: a coupled modelling approach
Constantijn J. Berends, Roderik S. W. van de Wal, Tim van den Akker, and William H. Lipscomb
The Cryosphere, 17, 1585–1600, https://doi.org/10.5194/tc-17-1585-2023, https://doi.org/10.5194/tc-17-1585-2023, 2023
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The rate at which the Antarctic ice sheet will melt because of anthropogenic climate change is uncertain. Part of this uncertainty stems from processes occurring beneath the ice, such as the way the ice slides over the underlying bedrock.
Inversion methodsattempt to use observations of the ice-sheet surface to calculate how these sliding processes work. We show that such methods cannot fully solve this problem, so a substantial uncertainty still remains in projections of sea-level rise.
Camilo Andrés Rada Giacaman and Christian Schoof
The Cryosphere, 17, 761–787, https://doi.org/10.5194/tc-17-761-2023, https://doi.org/10.5194/tc-17-761-2023, 2023
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Water flowing at the base of glaciers plays a crucial role in controlling the speed at which glaciers move and how glaciers react to climate. The processes happening below the glaciers are extremely hard to observe and remain only partially understood. Here we provide novel insight into the subglacial environment based on an extensive dataset with over 300 boreholes on an alpine glacier in the Yukon Territory. We highlight the importance of hydraulically disconnected regions of the glacier bed.
Kelly A. Hogan, Katarzyna L. P. Warburton, Alastair G. C. Graham, Jerome A. Neufeld, Duncan R. Hewitt, Julian A. Dowdeswell, and Robert D. Larter
The Cryosphere Discuss., https://doi.org/10.5194/tc-2022-222, https://doi.org/10.5194/tc-2022-222, 2022
Revised manuscript accepted for TC
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Delicate seafloor ridges – corrugation ridges – that form by tidal motion at Antarctic grounding lines record extremely fast retreat of ice streams in the past. Here we use a mathematical model, constrained by real-world observations from Thwaites Glacier, West Antarctica, to explore how corrugation ridges form. We identify “till extrusion”, whereby deformable sediment is squeezed out from under the ice like toothpaste as it settles down at each low-tide position, as the most likely process.
Dominic A. Hodgson, Tom A. Jordan, Neil Ross, Teal R. Riley, and Peter T. Fretwell
The Cryosphere, 16, 4797–4809, https://doi.org/10.5194/tc-16-4797-2022, https://doi.org/10.5194/tc-16-4797-2022, 2022
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This paper describes the drainage (and refill) of a subglacial lake on the Antarctic Peninsula resulting in the collapse of the overlying ice into the newly formed subglacial cavity. It provides evidence of an active hydrological network under the region's glaciers and close coupling between surface climate processes and the base of the ice.
Alexander O. Hager, Matthew J. Hoffman, Stephen F. Price, and Dustin M. Schroeder
The Cryosphere, 16, 3575–3599, https://doi.org/10.5194/tc-16-3575-2022, https://doi.org/10.5194/tc-16-3575-2022, 2022
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The presence of water beneath glaciers is a control on glacier speed and ocean-caused melting, yet it has been unclear whether sizable volumes of water can exist beneath Antarctic glaciers or how this water may flow along the glacier bed. We use computer simulations, supported by observations, to show that enough water exists at the base of Thwaites Glacier, Antarctica, to form "rivers" beneath the glacier. These rivers likely moderate glacier speed and may influence its rate of retreat.
Qi Liang, Wanxin Xiao, Ian Howat, Xiao Cheng, Fengming Hui, Zhuoqi Chen, Mi Jiang, and Lei Zheng
The Cryosphere, 16, 2671–2681, https://doi.org/10.5194/tc-16-2671-2022, https://doi.org/10.5194/tc-16-2671-2022, 2022
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Using multi-temporal ArcticDEM and ICESat-2 altimetry data, we document changes in surface elevation of a subglacial lake basin from 2012 to 2021. The long-term measurements show that the subglacial lake was recharged by surface meltwater and that a rapid drainage event in late August 2019 induced an abrupt ice velocity change. Multiple factors regulate the episodic filling and drainage of the lake. Our study also reveals ~ 64 % of the surface meltwater successfully descended to the bed.
Anja Rutishauser, Donald D. Blankenship, Duncan A. Young, Natalie S. Wolfenbarger, Lucas H. Beem, Mark L. Skidmore, Ashley Dubnick, and Alison S. Criscitiello
The Cryosphere, 16, 379–395, https://doi.org/10.5194/tc-16-379-2022, https://doi.org/10.5194/tc-16-379-2022, 2022
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Recently, a hypersaline subglacial lake complex was hypothesized to lie beneath Devon Ice Cap, Canadian Arctic. Here, we present results from a follow-on targeted aerogeophysical survey. Our results support the evidence for a hypersaline subglacial lake and reveal an extensive brine network, suggesting more complex subglacial hydrological conditions than previously inferred. This hypersaline system may host microbial habitats, making it a compelling analog for bines on other icy worlds.
Amy Jenson, Jason M. Amundson, Jonathan Kingslake, and Eran Hood
The Cryosphere, 16, 333–347, https://doi.org/10.5194/tc-16-333-2022, https://doi.org/10.5194/tc-16-333-2022, 2022
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Outburst floods are sudden releases of water from glacial environments. As glaciers retreat, changes in glacier and basin geometry impact outburst flood characteristics. We combine a glacier flow model describing glacier retreat with an outburst flood model to explore how ice dam height, glacier length, and remnant ice in a basin influence outburst floods. We find storage capacity is the greatest indicator of flood magnitude, and the flood onset mechanism is a significant indicator of duration.
Anna Derkacheva, Fabien Gillet-Chaulet, Jeremie Mouginot, Eliot Jager, Nathan Maier, and Samuel Cook
The Cryosphere, 15, 5675–5704, https://doi.org/10.5194/tc-15-5675-2021, https://doi.org/10.5194/tc-15-5675-2021, 2021
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Along the edges of the Greenland Ice Sheet surface melt lubricates the bed and causes large seasonal fluctuations in ice speeds during summer. Accurately understanding how these ice speed changes occur is difficult due to the inaccessibility of the glacier bed. We show that by using surface velocity maps with high temporal resolution and numerical modelling we can infer the basal conditions that control seasonal fluctuations in ice speed and gain insight into seasonal dynamics over large areas.
Huw J. Horgan, Laurine van Haastrecht, Richard B. Alley, Sridhar Anandakrishnan, Lucas H. Beem, Knut Christianson, Atsuhiro Muto, and Matthew R. Siegfried
The Cryosphere, 15, 1863–1880, https://doi.org/10.5194/tc-15-1863-2021, https://doi.org/10.5194/tc-15-1863-2021, 2021
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The grounding zone marks the transition from a grounded ice sheet to a floating ice shelf. Like Earth's coastlines, the grounding zone is home to interactions between the ocean, fresh water, and geology but also has added complexity and importance due to the overriding ice. Here we use seismic surveying – sending sound waves down through the ice – to image the grounding zone of Whillans Ice Stream in West Antarctica and learn more about the nature of this important transition zone.
Matej Lipar, Andrea Martín-Pérez, Jure Tičar, Miha Pavšek, Matej Gabrovec, Mauro Hrvatin, Blaž Komac, Matija Zorn, Nadja Zupan Hajna, Jian-Xin Zhao, Russell N. Drysdale, and Mateja Ferk
The Cryosphere, 15, 17–30, https://doi.org/10.5194/tc-15-17-2021, https://doi.org/10.5194/tc-15-17-2021, 2021
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The U–Th ages of subglacial carbonate deposits from a recently exposed surface previously occupied by the disappearing glacier in the SE European Alps suggest the glacier’s presence throughout the entire Holocene. These thin deposits, formed by regelation, would have been easily eroded if exposed during previous Holocene climatic optima. The age data indicate the glacier’s present unprecedented level of retreat and the potential of subglacial carbonates to act as palaeoclimate proxies.
Andrew O. Hoffman, Knut Christianson, Daniel Shapero, Benjamin E. Smith, and Ian Joughin
The Cryosphere, 14, 4603–4609, https://doi.org/10.5194/tc-14-4603-2020, https://doi.org/10.5194/tc-14-4603-2020, 2020
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The West Antarctic Ice Sheet has long been considered geometrically prone to collapse, and Thwaites Glacier, the largest glacier in the Amundsen Sea, is likely in the early stages of disintegration. Using observations of Thwaites Glacier velocity and elevation change, we show that the transport of ~2 km3 of water beneath Thwaites Glacier has only a small and transient effect on glacier speed relative to ongoing thinning driven by ocean melt.
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, https://doi.org/10.5194/tc-14-4507-2020, https://doi.org/10.5194/tc-14-4507-2020, 2020
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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.
Slawek M. Tulaczyk and Neil T. Foley
The Cryosphere, 14, 4495–4506, https://doi.org/10.5194/tc-14-4495-2020, https://doi.org/10.5194/tc-14-4495-2020, 2020
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Much of what we know about materials hidden beneath glaciers and ice sheets on Earth has been interpreted using radar reflection from the ice base. A common assumption is that electrical conductivity of the sub-ice materials does not influence the reflection strength and that the latter is controlled only by permittivity, which depends on the fraction of water in these materials. Here we argue that sub-ice electrical conductivity should be generally considered when interpreting radar records.
Andreas Alexander, Jaroslav Obu, Thomas V. Schuler, Andreas Kääb, and Hanne H. Christiansen
The Cryosphere, 14, 4217–4231, https://doi.org/10.5194/tc-14-4217-2020, https://doi.org/10.5194/tc-14-4217-2020, 2020
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In this study we present subglacial air, ice and sediment temperatures from within the basal drainage systems of two cold-based glaciers on Svalbard during late spring and the summer melt season. We put the data into the context of air temperature and rainfall at the glacier surface and show the importance of surface events on the subglacial thermal regime and erosion around basal drainage channels. Observed vertical erosion rates thereby reachup to 0.9 m d−1.
Alex Burton-Johnson, Ricarda Dziadek, and Carlos Martin
The Cryosphere, 14, 3843–3873, https://doi.org/10.5194/tc-14-3843-2020, https://doi.org/10.5194/tc-14-3843-2020, 2020
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The Antarctic ice sheet is the largest source for sea level rise. However, one key control on ice sheet flow remains poorly constrained: the effect of heat from the rocks beneath the ice sheet (known as
geothermal heat flow). Although this may not seem like a lot of heat, beneath thick, slow ice this heat can control how well the ice flows and can lead to melting of the ice sheet. We discuss the methods used to estimate this heat, compile existing data, and recommend future research.
Ugo Nanni, Florent Gimbert, Christian Vincent, Dominik Gräff, Fabian Walter, Luc Piard, and Luc Moreau
The Cryosphere, 14, 1475–1496, https://doi.org/10.5194/tc-14-1475-2020, https://doi.org/10.5194/tc-14-1475-2020, 2020
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Our study addresses key questions on the subglacial drainage system physics through a novel observational approach that overcomes traditional limitations. We conducted, over 2 years, measurements of the subglacial water-flow-induced seismic noise and of glacier basal sliding speeds. We then inverted for the subglacial channel's hydraulic pressure gradient and hydraulic radius and investigated the links between the equilibrium state of subglacial channels and glacier basal sliding.
Silje Smith-Johnsen, Basile de Fleurian, Nicole Schlegel, Helene Seroussi, and Kerim Nisancioglu
The Cryosphere, 14, 841–854, https://doi.org/10.5194/tc-14-841-2020, https://doi.org/10.5194/tc-14-841-2020, 2020
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The Northeast Greenland Ice Stream (NEGIS) drains a large part of Greenland and displays fast flow far inland. However, the flow pattern is not well represented in ice sheet models. The fast flow has been explained by abnormally high geothermal heat flux. The heat melts the base of the ice sheet and the water produced may lubricate the bed and induce fast flow. By including high geothermal heat flux and a hydrology model, we successfully reproduce NEGIS flow pattern in an ice sheet model.
Fabian Lindner, Fabian Walter, Gabi Laske, and Florent Gimbert
The Cryosphere, 14, 287–308, https://doi.org/10.5194/tc-14-287-2020, https://doi.org/10.5194/tc-14-287-2020, 2020
Michael A. Cooper, Thomas M. Jordan, Dustin M. Schroeder, Martin J. Siegert, Christopher N. Williams, and Jonathan L. Bamber
The Cryosphere, 13, 3093–3115, https://doi.org/10.5194/tc-13-3093-2019, https://doi.org/10.5194/tc-13-3093-2019, 2019
Edyta Łokas, Agata Zaborska, Ireneusz Sobota, Paweł Gaca, J. Andrew Milton, Paweł Kocurek, and Anna Cwanek
The Cryosphere, 13, 2075–2086, https://doi.org/10.5194/tc-13-2075-2019, https://doi.org/10.5194/tc-13-2075-2019, 2019
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Cryoconite granules built of mineral particles, organic substances and living organisms significantly influence fluxes of energy and matter at glacier surfaces. They contribute to ice melting, give rise to an exceptional ecosystem, and effectively trap contaminants. This study evaluates contamination levels of radionuclides in cryoconite from Arctic glaciers and identifies sources of this contamination, proving that cryoconite is an excellent indicator of atmospheric contamination.
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, https://doi.org/10.5194/tc-13-1583-2019, https://doi.org/10.5194/tc-13-1583-2019, 2019
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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.
Benedict T. I. Reinardy, Adam D. Booth, Anna L. C. Hughes, Clare M. Boston, Henning Åkesson, Jostein Bakke, Atle Nesje, Rianne H. Giesen, and Danni M. Pearce
The Cryosphere, 13, 827–843, https://doi.org/10.5194/tc-13-827-2019, https://doi.org/10.5194/tc-13-827-2019, 2019
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Cold-ice processes may be widespread within temperate glacier systems but the role of cold-ice processes in temperate glacier systems is relatively unknown. Climate forcing is the main control on glacier mass balance but potential for heterogeneous thermal conditions at temperate glaciers calls for improved model assessments of future evolution of thermal conditions and impacts on glacier dynamics and mass balance. Cold-ice processes need to be included in temperate glacier land system models.
Joseph Graly, Joel Harrington, and Neil Humphrey
The Cryosphere, 11, 1131–1140, https://doi.org/10.5194/tc-11-1131-2017, https://doi.org/10.5194/tc-11-1131-2017, 2017
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At a major outlet of the Greenland Ice Sheet in West Greenland, we find that the chemical solutes in the emerging subglacial waters are out of phase with water discharge and can spike in concentration during waning flow. This suggests that the subglacial waters are spreading out across a large area of the glacial bed throughout the day, stimulating chemical weathering beyond the major water distribution channels.
Benjamin E. Smith, Noel Gourmelen, Alexander Huth, and Ian Joughin
The Cryosphere, 11, 451–467, https://doi.org/10.5194/tc-11-451-2017, https://doi.org/10.5194/tc-11-451-2017, 2017
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In this paper we investigate elevation changes of Thwaites Glacier, West Antarctica, one of the main sources of excess ice discharge into the ocean. We find that in early 2013, four subglacial lakes separated by 100 km drained suddenly, discharging more than 3 km3 of water under the fastest part of the glacier in less than 6 months. Concurrent ice-speed measurements show only minor changes, suggesting that ice dynamics are not strongly sensitive to changes in water flow.
Byeong-Hoon Kim, Choon-Ki Lee, Ki-Weon Seo, Won Sang Lee, and Ted Scambos
The Cryosphere, 10, 2971–2980, https://doi.org/10.5194/tc-10-2971-2016, https://doi.org/10.5194/tc-10-2971-2016, 2016
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Kamb Ice Stream (KIS) in Antarctica ceased rapid ice flow approximately 160 years ago, still influencing on the current mass balance of the West Antarctic Ice Sheet. We identify two previously unknown subglacial lakes beneath the stagnated trunk of the KIS. Rapid fill-drain hydrologic events over several months indicate that the lakes are probably connected by a subglacial drainage network. Our findings support previously published conceptual models of the KIS shutdown.
Maarten Krabbendam
The Cryosphere, 10, 1915–1932, https://doi.org/10.5194/tc-10-1915-2016, https://doi.org/10.5194/tc-10-1915-2016, 2016
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The way that ice moves over rough ground at the base of an ice sheet is important to understand and predict the behaviour of ice sheets. Here, I argue that if basal ice is at the melting temperature, as is locally the case below the Greenland Ice Sheet, this basal motion is easier and faster than hitherto thought. A thick (tens of metres) layer of ice at the melting temperature may better explain some ice streams and needs to be taken into account when modelling future ice sheet behaviour.
Takahiro Abe, Masato Furuya, and Daiki Sakakibara
The Cryosphere, 10, 1427–1432, https://doi.org/10.5194/tc-10-1427-2016, https://doi.org/10.5194/tc-10-1427-2016, 2016
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We identified 12-year cyclic surging episodes at Donjek Glacier in Yukon, Canada. The surging area is limited within the ~20km section from the terminus, originating in an area where the flow width significantly narrows downstream. Our results suggest strong control of the valley constriction on the surge dynamics.
B. P. Lipovsky and E. M. Dunham
The Cryosphere, 10, 385–399, https://doi.org/10.5194/tc-10-385-2016, https://doi.org/10.5194/tc-10-385-2016, 2016
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Small repeating earthquakes occur at the ice-bed interface of the Whillans Ice Stream, West Antarctica. The earthquakes occur as rapidly as 20 earthquakes/s. We conduct numerical simulations of these earthquakes that include elastic and frictional forces as well as seismic wave propagation. We create synthetic seismograms and compare these synthetics to observed seismograms in order to constrain subglacial parameters. We comment on decadal-scale changes in these parameters.
D. Callens, K. Matsuoka, D. Steinhage, B. Smith, E. Witrant, and F. Pattyn
The Cryosphere, 8, 867–875, https://doi.org/10.5194/tc-8-867-2014, https://doi.org/10.5194/tc-8-867-2014, 2014
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, https://doi.org/10.5194/tc-8-15-2014, https://doi.org/10.5194/tc-8-15-2014, 2014
S. Goeller, M. Thoma, K. Grosfeld, and H. Miller
The Cryosphere, 7, 1095–1106, https://doi.org/10.5194/tc-7-1095-2013, https://doi.org/10.5194/tc-7-1095-2013, 2013
M. Thoma, K. Grosfeld, C. Mayer, A. M. Smith, J. Woodward, and N. Ross
The Cryosphere, 5, 561–567, https://doi.org/10.5194/tc-5-561-2011, https://doi.org/10.5194/tc-5-561-2011, 2011
M. Thoma, K. Grosfeld, C. Mayer, and F. Pattyn
The Cryosphere, 4, 1–12, https://doi.org/10.5194/tc-4-1-2010, https://doi.org/10.5194/tc-4-1-2010, 2010
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Short summary
This paper details a new algorithm for performing computational experiments of subglacial granular deformation. The numerical approach allows detailed studies of internal sediment and pore-water dynamics under shear. Feedbacks between sediment grains and pore water can cause rate-dependent strengthening, which additionally contributes to the plastic shear strength of the granular material. Hardening can stabilise patches of the subglacial beds with implications for landform development.
This paper details a new algorithm for performing computational experiments of subglacial...
