Articles | Volume 11, issue 3
https://doi.org/10.5194/tc-11-1131-2017
© Author(s) 2017. 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-11-1131-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
05 May 2017
Research article |
| 05 May 2017
Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet, Greenland Ice Sheet
Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave.
Laramie, WY 82071, USA
Joel Harrington
Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave.
Laramie, WY 82071, USA
Neil Humphrey
Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave.
Laramie, WY 82071, USA
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Anja Løkkegaard, Kenneth D. Mankoff, Christian Zdanowicz, Gary D. Clow, Martin P. Lüthi, Samuel H. Doyle, Henrik H. Thomsen, David Fisher, Joel Harper, Andy Aschwanden, Bo M. Vinther, Dorthe Dahl-Jensen, Harry Zekollari, Toby Meierbachtol, Ian McDowell, Neil Humphrey, Anne Solgaard, Nanna B. Karlsson, Shfaqat A. Khan, Benjamin Hills, Robert Law, Bryn Hubbard, Poul Christoffersen, Mylène Jacquemart, Julien Seguinot, Robert S. Fausto, and William T. Colgan
The Cryosphere, 17, 3829–3845, https://doi.org/10.5194/tc-17-3829-2023, https://doi.org/10.5194/tc-17-3829-2023, 2023
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This study presents a database compiling 95 ice temperature profiles from the Greenland ice sheet and peripheral ice caps. Ice viscosity and hence ice flow are highly sensitive to ice temperature. To highlight the value of the database in evaluating ice flow simulations, profiles from the Greenland ice sheet are compared to a modeled temperature field. Reoccurring discrepancies between modeled and observed temperatures provide insight on the difficulties faced when simulating ice temperatures.
Joel Harper, Toby Meierbachtol, Neil Humphrey, Jun Saito, and Aidan Stansberry
The Cryosphere, 15, 5409–5421, https://doi.org/10.5194/tc-15-5409-2021, https://doi.org/10.5194/tc-15-5409-2021, 2021
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We use surface and borehole measurements to investigate the generation and fate of basal meltwater in the ablation zone of western Greenland. The rate of basal meltwater generation at borehole study sites increases by up to 20 % over the winter period. Accommodation of all basal meltwater by expansion of isolated subglacial cavities is implausible. Other sinks for water do not likely balance basal meltwater generation, implying water evacuation through a connected drainage system in winter.
Ian E. McDowell, Neil F. Humphrey, Joel T. Harper, and Toby W. Meierbachtol
The Cryosphere, 15, 897–907, https://doi.org/10.5194/tc-15-897-2021, https://doi.org/10.5194/tc-15-897-2021, 2021
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Ice temperature controls rates of internal deformation and the onset of basal sliding. To identify heat transfer mechanisms and englacial heat sources within Greenland's ablation zone, we examine a 2–3-year continuous temperature record from nine full-depth boreholes. Thermal decay after basal crevasses release heat in the near-basal ice likely produces the observed cooling. Basal crevasses in Greenland can affect the basal ice rheology and indicate a potentially complex basal hydrologic system.
Rosemary Leone, Joel Harper, Toby Meierbachtol, and Neil Humphrey
The Cryosphere, 14, 1703–1712, https://doi.org/10.5194/tc-14-1703-2020, https://doi.org/10.5194/tc-14-1703-2020, 2020
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Horizontal ice flow transports the firn layer of Greenland’s Percolation Zone as it undergoes burial by accumulation. Here we show that the firn density and temperature fields can reflect horizontal advection of the firn column across climate gradients, the magnitude of which varies around the ice sheet. Further, time series of melt features in ice cores from the percolation zone can contain a signature from ice motion that should not be conflated with that from climate change.
Benjamin H. Hills, Joel T. Harper, Toby W. Meierbachtol, Jesse V. Johnson, Neil F. Humphrey, and Patrick J. Wright
The Cryosphere, 12, 3215–3227, https://doi.org/10.5194/tc-12-3215-2018, https://doi.org/10.5194/tc-12-3215-2018, 2018
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At its surface, an ice sheet is closely connected to the climate. Assessing heat transfer between near-surface ice and the overlying atmosphere is important for understanding how the ice sheet is melting at the surface. We measured ice temperature within 20 m of the surface of the Greenland Ice Sheet. Resulting ice temperatures are warmer than the air, a peculiar result which implies the role of some nonconductive heat transfer processes such as latent heating by refreezing meltwater.
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
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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.
C. Cox, N. Humphrey, and J. Harper
The Cryosphere, 9, 691–701, https://doi.org/10.5194/tc-9-691-2015, https://doi.org/10.5194/tc-9-691-2015, 2015
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On the Greenland Ice Sheet, a significant quantity of surface melt water refreezes after infiltrating into the cold underlying firn. This paper presents a new method for estimating the amount of water refreezing using temperature measurements. The method is applied to temperature data from a transect of 11 sites and the results provide some of the first measurement-based estimates of refreezing quantities which can be used to improve modeling and better understand the refreezing process.
Related subject area
Subglacial Processes
Misidentified subglacial lake beneath the Devon Ice Cap, Canadian Arctic: a new interpretation from seismic and electromagnetic data
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard
Geothermal heat source estimations through ice flow modelling at Mýrdalsjökull, Iceland
Improved monitoring of subglacial lake activity in Greenland
Impact of shallow sills on circulation regimes and submarine melting in glacial fjords
Basal conditions of Denman Glacier from glacier hydrology and ice dynamics modeling
Mapping age and basal conditions of ice in the Dome Fuji region, Antarctica, by combining radar internal layer stratigraphy and flow modeling
Towards modelling of corrugation ridges at ice-sheet grounding lines
Differential impact of isolated topographic bumps on ice sheet flow and 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
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
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
A new methodology to simulate subglacial deformation of water-saturated granular material
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
Siobhan F. Killingbeck, Anja Rutishauser, Martyn J. Unsworth, Ashley Dubnick, Alison S. Criscitiello, James Killingbeck, Christine F. Dow, Tim Hill, Adam D. Booth, Brittany Main, and Eric Brossier
The Cryosphere, 18, 3699–3722, https://doi.org/10.5194/tc-18-3699-2024, https://doi.org/10.5194/tc-18-3699-2024, 2024
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A subglacial lake was proposed to exist beneath Devon Ice Cap in the Canadian Arctic based on the analysis of airborne data. Our study presents a new interpretation of the subglacial material beneath the Devon Ice Cap from surface-based geophysical data. We show that there is no evidence of subglacial water, and the subglacial lake has likely been misidentified. Re-evaluation of the airborne data shows that overestimation of a critical processing parameter has likely occurred in prior studies.
Coline Bouchayer, Ugo Nanni, Pierre-Marie Lefeuvre, John Hult, Louise Steffensen Schmidt, Jack Kohler, François Renard, and Thomas V. Schuler
The Cryosphere, 18, 2939–2968, https://doi.org/10.5194/tc-18-2939-2024, https://doi.org/10.5194/tc-18-2939-2024, 2024
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We explore the interplay between surface runoff and subglacial conditions. We focus on Kongsvegen glacier in Svalbard. We drilled 350 m down to the glacier base to measure water pressure, till strength, seismic noise, and glacier surface velocity. In the low-melt season, the drainage system adapted gradually, while the high-melt season led to a transient response, exceeding drainage capacity and enhancing sliding. Our findings contribute to discussions on subglacial hydro-mechanical processes.
Alexander H. Jarosch, Eyjólfur Magnússon, Krista Hannesdóttir, Joaquín M. C. Belart, and Finnur Pálsson
The Cryosphere, 18, 2443–2454, https://doi.org/10.5194/tc-18-2443-2024, https://doi.org/10.5194/tc-18-2443-2024, 2024
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Geothermally active regions beneath glaciers not only influence local ice flow as well as the mass balance of glaciers but also control changes of subglacial water reservoirs and possible subsequent glacier lake outburst floods. In Iceland, such outburst floods impose danger to people and infrastructure and are therefore monitored. We present a novel computer-simulation-supported method to estimate the activity of such geothermal areas and to monitor its evolution.
Louise Sandberg Sørensen, Rasmus Bahbah, Sebastian B. Simonsen, Natalia Havelund Andersen, Jade Bowling, Noel Gourmelen, Alex Horton, Nanna B. Karlsson, Amber Leeson, Jennifer Maddalena, Malcolm McMillan, Anne Solgaard, and Birgit Wessel
The Cryosphere, 18, 505–523, https://doi.org/10.5194/tc-18-505-2024, https://doi.org/10.5194/tc-18-505-2024, 2024
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Under the right topographic and hydrological conditions, lakes may form beneath the large ice sheets. Some of these subglacial lakes are active, meaning that they periodically drain and refill. When a subglacial lake drains rapidly, it may cause the ice surface above to collapse, and here we investigate how to improve the monitoring of active subglacial lakes in Greenland by monitoring how their associated collapse basins change over time.
Weiyang Bao and Carlos Moffat
The Cryosphere, 18, 187–203, https://doi.org/10.5194/tc-18-187-2024, https://doi.org/10.5194/tc-18-187-2024, 2024
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A shallow sill can promote the downward transport of the upper-layer freshwater outflow in proglacial fjords. This sill-driven transport reduces fjord temperature and stratification. The sill depth, freshwater discharge, fjord temperature, and stratification are key parameters that modulate the heat supply towards glaciers. Additionally, the relative depth of the plume outflow, the fjord, and the sill can be used to characterize distinct circulation and heat transport regimes in glacial fjords.
Koi McArthur, Felicity S. McCormack, and Christine F. Dow
The Cryosphere, 17, 4705–4727, https://doi.org/10.5194/tc-17-4705-2023, https://doi.org/10.5194/tc-17-4705-2023, 2023
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Using subglacial hydrology model outputs for Denman Glacier, East Antarctica, we investigated the effects of various friction laws and effective pressure inputs on ice dynamics modeling over the same glacier. The Schoof friction law outperformed the Budd friction law, and effective pressure outputs from the hydrology model outperformed a typically prescribed effective pressure. We propose an empirical prescription of effective pressure to be used in the absence of hydrology model outputs.
Zhuo Wang, Ailsa Chung, Daniel Steinhage, Frédéric Parrenin, Johannes Freitag, and Olaf Eisen
The Cryosphere, 17, 4297–4314, https://doi.org/10.5194/tc-17-4297-2023, https://doi.org/10.5194/tc-17-4297-2023, 2023
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We combine radar-based observed internal layer stratigraphy of the ice sheet with a 1-D ice flow model in the Dome Fuji region. This results in maps of age and age density of the basal ice, the basal thermal conditions, and reconstructed accumulation rates. Based on modeled age we then identify four potential candidates for ice which is potentially 1.5 Myr old. Our map of basal thermal conditions indicates that melting prevails over the presence of stagnant ice in the study area.
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, 17, 2645–2664, https://doi.org/10.5194/tc-17-2645-2023, https://doi.org/10.5194/tc-17-2645-2023, 2023
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Delicate sea floor 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.
Marion A. McKenzie, Lauren E. Miller, Jacob S. Slawson, Emma J. MacKie, and Shujie Wang
The Cryosphere, 17, 2477–2486, https://doi.org/10.5194/tc-17-2477-2023, https://doi.org/10.5194/tc-17-2477-2023, 2023
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Topographic highs (“bumps”) across glaciated landscapes have the potential to affect glacial ice. Bumps in the deglaciated Puget Lowland are assessed for streamlined glacial features to provide insight on ice–bed interactions. We identify a general threshold in which bumps significantly disrupt ice flow and sedimentary processes in this location. However, not all bumps have the same degree of impact. The system assessed here has relevance to parts of the Greenland Ice Sheet and Thwaites Glacier.
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.
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.
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.
A. Damsgaard, D. L. Egholm, J. A. Piotrowski, S. Tulaczyk, N. K. Larsen, and C. F. Brædstrup
The Cryosphere, 9, 2183–2200, https://doi.org/10.5194/tc-9-2183-2015, https://doi.org/10.5194/tc-9-2183-2015, 2015
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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.
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
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.
At a major outlet of the Greenland Ice Sheet in West Greenland, we find that the chemical...
