Articles | Volume 14, issue 12
https://doi.org/10.5194/tc-14-4603-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-14-4603-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Brief communication
| Highlight paper
| 
18 Dec 2020
Brief communication | Highlight paper |
| 18 Dec 2020
| 18 Dec 2020
Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica
Andrew O. Hoffman
CORRESPONDING AUTHOR
Department of Earth and Space Sciences, University of Washington, Seattle, WA 98115, USA
Knut Christianson
CORRESPONDING AUTHOR
Department of Earth and Space Sciences, University of Washington, Seattle, WA 98115, USA
Daniel Shapero
Applied Physics Laboratory, University of Washington, Seattle, WA 98115, USA
Benjamin E. Smith
Applied Physics Laboratory, University of Washington, Seattle, WA 98115, USA
Ian Joughin
Applied Physics Laboratory, University of Washington, Seattle, WA 98115, USA
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Michelle L. Maclennan, Jan T. M. Lenaerts, Christine A. Shields, Andrew O. Hoffman, Nander Wever, Megan Thompson-Munson, Andrew C. Winters, Erin C. Pettit, Theodore A. Scambos, and Jonathan D. Wille
The Cryosphere, 17, 865–881, https://doi.org/10.5194/tc-17-865-2023, https://doi.org/10.5194/tc-17-865-2023, 2023
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Atmospheric rivers are air masses that transport large amounts of moisture and heat towards the poles. Here, we use a combination of weather observations and models to quantify the amount of snowfall caused by atmospheric rivers in West Antarctica which is about 10 % of the total snowfall each year. We then examine a unique event that occurred in early February 2020, when three atmospheric rivers made landfall over West Antarctica in rapid succession, leading to heavy snowfall and surface melt.
Daniel R. Shapero, Jessica A. Badgeley, Andrew O. Hoffman, and Ian R. Joughin
Geosci. Model Dev., 14, 4593–4616, https://doi.org/10.5194/gmd-14-4593-2021, https://doi.org/10.5194/gmd-14-4593-2021, 2021
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This paper describes a new software package called "icepack" for modeling the flow of ice sheets and glaciers. Glaciologists use tools like icepack to better understand how ice sheets flow, what role they have played in shaping Earth's climate, and how much sea level rise we can expect in the coming decades to centuries. The icepack package includes several innovations to help researchers describe and solve interesting glaciological problems and to experiment with the underlying model physics.
Andrew Bliss, Regine Hock, Gabriel Wolken, Erin Whorton, Caroline Aubry-Wake, Juliana Braun, Alessio Gusmeroli, Will Harrison, Andrew Hoffman, Anna Liljedahl, and Jing Zhang
Earth Syst. Sci. Data, 12, 403–427, https://doi.org/10.5194/essd-12-403-2020, https://doi.org/10.5194/essd-12-403-2020, 2020
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Extensive field observations were conducted in the Upper Susitna basin in central Alaska in 2012–2014. This paper describes the weather, glacier mass balance, snow cover, and soils of the basin. We found that temperatures over the glacier are cooler than over land at the same elevation. The glaciers have been losing mass faster in recent years than in the 1980s. Measurements of glacier mass change with traditional methods closely matched radar measurements.
Andrew O. Hoffman, Hans Christian Steen-Larsen, Knut Christianson, and Christine Hvidberg
Geosci. Instrum. Method. Data Syst., 8, 149–159, https://doi.org/10.5194/gi-8-149-2019, https://doi.org/10.5194/gi-8-149-2019, 2019
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We present the design considerations and deployment of an autonomous modular terrestrial rover for ice-sheet exploration that is inexpensive, easy to construct, and allows for instrumentation customization. The rover proved capable of driving over 20 km on a single charge with a drawbar pull of 250 N, which is sufficient to tow commercial ground-penetrating radars. Due to its low cost, low power requirements, and simple modular design, mass deployments of this rover design are practicable.
Twila A. Moon, Benjamin Cohen, Taryn E. Black, Kristin L. Laidre, Harry L. Stern, and Ian Joughin
The Cryosphere, 18, 4845–4872, https://doi.org/10.5194/tc-18-4845-2024, https://doi.org/10.5194/tc-18-4845-2024, 2024
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The complex geomorphology of southeast Greenland (SEG) creates dynamic fjord habitats for top marine predators, featuring glacier-derived floating ice, pack and landfast sea ice, and freshwater flux. We study the physical environment of SEG fjords, focusing on surface ice conditions, to provide a regional characterization that supports biological research. As Arctic warming persists, SEG may serve as a long-term refugium for ice-dependent wildlife due to the persistence of regional ice sheets.
Reuben W. Nixon-Hill, Daniel Shapero, Colin J. Cotter, and David A. Ham
Geosci. Model Dev., 17, 5369–5386, https://doi.org/10.5194/gmd-17-5369-2024, https://doi.org/10.5194/gmd-17-5369-2024, 2024
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Scientists often use models to study complex processes, like the movement of ice sheets, and compare them to measurements for estimating quantities that are hard to measure. We highlight an approach that ensures accurate results from point data sources (e.g. height measurements) by evaluating the numerical solution at true point locations. This method improves accuracy, aids communication between scientists, and is well-suited for integration with specialised software that automates processes.
Michael Studinger, Benjamin E. Smith, Nathan Kurtz, Alek Petty, Tyler Sutterley, and Rachel Tilling
The Cryosphere, 18, 2625–2652, https://doi.org/10.5194/tc-18-2625-2024, https://doi.org/10.5194/tc-18-2625-2024, 2024
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We use green lidar data and natural-color imagery over sea ice to quantify elevation biases potentially impacting estimates of change in ice thickness of the polar regions. We complement our analysis using a model of scattering of light in snow and ice that predicts the shape of lidar waveforms reflecting from snow and ice surfaces based on the shape of the transmitted pulse. We find that biased elevations exist in airborne and spaceborne data products from green lidars.
Ian Joughin, Daniel Shapero, and Pierre Dutrieux
The Cryosphere, 18, 2583–2601, https://doi.org/10.5194/tc-18-2583-2024, https://doi.org/10.5194/tc-18-2583-2024, 2024
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The Pine Island and Thwaites glaciers are losing ice to the ocean rapidly as warmer water melts their floating ice shelves. Models help determine how much such glaciers will contribute to sea level. We find that ice loss varies in response to how much melting the ice shelves are subjected to. Our estimated losses are also sensitive to how much the friction beneath the glaciers is reduced as it goes afloat. Melt-forced sea level rise from these glaciers is likely to be less than 10 cm by 2300.
Allison M. Chartrand, Ian M. Howat, Ian R. Joughin, and Benjamin E. Smith
EGUsphere, https://doi.org/10.5194/egusphere-2024-1132, https://doi.org/10.5194/egusphere-2024-1132, 2024
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This study uses high-resolution remote sensing data to show that shrinking of the West Antarctic Thwaites Glacier’s ice shelf (floating extension) is exacerbated by the presence of sub–ice shelf meltwater channels that form as the glacier transitions from full contact with the bed to fully floating. In mapping these channels, the position of the transition zone, and thinning rates of the Thwaites Glacier, this work elucidates important processes driving its rapid contribution to sea level rise.
Andrew O. Hoffman, Knut Christianson, Ching-Yao Lai, Ian Joughin, Nicholas Holschuh, Elizabeth Case, Jonathan Kingslake, and the GHOST science team
EGUsphere, https://doi.org/10.5194/egusphere-2023-2956, https://doi.org/10.5194/egusphere-2023-2956, 2024
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We use satellite and ice-penetrating radar technology to segment crevasses in the Amundsen Sea Embayment. Inspection of satellite time series reveals inland expansion of crevasses where surface stresses have increased. We develop a simple model for the strength of densifying snow and show that these crevasses are likely restricted to the near surface. This result bridges discrepancies between satellite and lab experiments and reveals the importance of porosity on surface crevasse formation.
Benjamin Smith, Michael Studinger, Tyler Sutterley, Zachary Fair, and Thomas Neumann
The Cryosphere Discuss., https://doi.org/10.5194/tc-2023-147, https://doi.org/10.5194/tc-2023-147, 2023
Revised manuscript has not been submitted
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This study investigates errors (biases) that may result when green lasers are used to measure the elevation of glaciers and ice sheets. These biases are important because if the snow or ice on top of the ice sheet changes, it can make the elevation of the ice appear to change by the wrong amount. We measure these biases over the Greenland Ice Sheet with a laser system on an airplane, and explore how the use of satellite data can let us correct for the biases.
Andrew O. Hoffman, Michelle Maclennan, Jan Lenaerts, Kristine M. Larson, and Knut Chrsitianson
The Cryosphere Discuss., https://doi.org/10.5194/tc-2023-114, https://doi.org/10.5194/tc-2023-114, 2023
Preprint under review for TC
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Traditionally, glaciologists have used GNSS to measure the surface elevation, and velocity of glaciers to understand processes associated with ice flow. Using the interference of GNSS signals that bounce off of the ice sheet surface, we measure the surface height change of several receivers in the Amundsen Sea Embayment. From surface height change, we infer accumulation records and use these records to understand the drivers of extreme precipitation on Thwaites Glacier.
Alice C. Frémand, Peter Fretwell, Julien A. Bodart, Hamish D. Pritchard, Alan Aitken, Jonathan L. Bamber, Robin Bell, Cesidio Bianchi, Robert G. Bingham, Donald D. Blankenship, Gino Casassa, Ginny Catania, Knut Christianson, Howard Conway, Hugh F. J. Corr, Xiangbin Cui, Detlef Damaske, Volkmar Damm, Reinhard Drews, Graeme Eagles, Olaf Eisen, Hannes Eisermann, Fausto Ferraccioli, Elena Field, René Forsberg, Steven Franke, Shuji Fujita, Yonggyu Gim, Vikram Goel, Siva Prasad Gogineni, Jamin Greenbaum, Benjamin Hills, Richard C. A. Hindmarsh, Andrew O. Hoffman, Per Holmlund, Nicholas Holschuh, John W. Holt, Annika N. Horlings, Angelika Humbert, Robert W. Jacobel, Daniela Jansen, Adrian Jenkins, Wilfried Jokat, Tom Jordan, Edward King, Jack Kohler, William Krabill, Mette Kusk Gillespie, Kirsty Langley, Joohan Lee, German Leitchenkov, Carlton Leuschen, Bruce Luyendyk, Joseph MacGregor, Emma MacKie, Kenichi Matsuoka, Mathieu Morlighem, Jérémie Mouginot, Frank O. Nitsche, Yoshifumi Nogi, Ole A. Nost, John Paden, Frank Pattyn, Sergey V. Popov, Eric Rignot, David M. Rippin, Andrés Rivera, Jason Roberts, Neil Ross, Anotonia Ruppel, Dustin M. Schroeder, Martin J. Siegert, Andrew M. Smith, Daniel Steinhage, Michael Studinger, Bo Sun, Ignazio Tabacco, Kirsty Tinto, Stefano Urbini, David Vaughan, Brian C. Welch, Douglas S. Wilson, Duncan A. Young, and Achille Zirizzotti
Earth Syst. Sci. Data, 15, 2695–2710, https://doi.org/10.5194/essd-15-2695-2023, https://doi.org/10.5194/essd-15-2695-2023, 2023
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This paper presents the release of over 60 years of ice thickness, bed elevation, and surface elevation data acquired over Antarctica by the international community. These data are a crucial component of the Antarctic Bedmap initiative which aims to produce a new map and datasets of Antarctic ice thickness and bed topography for the international glaciology and geophysical community.
Inès N. Otosaka, Andrew Shepherd, Erik R. Ivins, Nicole-Jeanne Schlegel, Charles Amory, Michiel R. van den Broeke, Martin Horwath, Ian Joughin, Michalea D. King, Gerhard Krinner, Sophie Nowicki, Anthony J. Payne, Eric Rignot, Ted Scambos, Karen M. Simon, Benjamin E. Smith, Louise S. Sørensen, Isabella Velicogna, Pippa L. Whitehouse, Geruo A, Cécile Agosta, Andreas P. Ahlstrøm, Alejandro Blazquez, William Colgan, Marcus E. Engdahl, Xavier Fettweis, Rene Forsberg, Hubert Gallée, Alex Gardner, Lin Gilbert, Noel Gourmelen, Andreas Groh, Brian C. Gunter, Christopher Harig, Veit Helm, Shfaqat Abbas Khan, Christoph Kittel, Hannes Konrad, Peter L. Langen, Benoit S. Lecavalier, Chia-Chun Liang, Bryant D. Loomis, Malcolm McMillan, Daniele Melini, Sebastian H. Mernild, Ruth Mottram, Jeremie Mouginot, Johan Nilsson, Brice Noël, Mark E. Pattle, William R. Peltier, Nadege Pie, Mònica Roca, Ingo Sasgen, Himanshu V. Save, Ki-Weon Seo, Bernd Scheuchl, Ernst J. O. Schrama, Ludwig Schröder, Sebastian B. Simonsen, Thomas Slater, Giorgio Spada, Tyler C. Sutterley, Bramha Dutt Vishwakarma, Jan Melchior van Wessem, David Wiese, Wouter van der Wal, and Bert Wouters
Earth Syst. Sci. Data, 15, 1597–1616, https://doi.org/10.5194/essd-15-1597-2023, https://doi.org/10.5194/essd-15-1597-2023, 2023
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By measuring changes in the volume, gravitational attraction, and ice flow of Greenland and Antarctica from space, we can monitor their mass gain and loss over time. Here, we present a new record of the Earth’s polar ice sheet mass balance produced by aggregating 50 satellite-based estimates of ice sheet mass change. This new assessment shows that the ice sheets have lost (7.5 x 1012) t of ice between 1992 and 2020, contributing 21 mm to sea level rise.
Michelle L. Maclennan, Jan T. M. Lenaerts, Christine A. Shields, Andrew O. Hoffman, Nander Wever, Megan Thompson-Munson, Andrew C. Winters, Erin C. Pettit, Theodore A. Scambos, and Jonathan D. Wille
The Cryosphere, 17, 865–881, https://doi.org/10.5194/tc-17-865-2023, https://doi.org/10.5194/tc-17-865-2023, 2023
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Atmospheric rivers are air masses that transport large amounts of moisture and heat towards the poles. Here, we use a combination of weather observations and models to quantify the amount of snowfall caused by atmospheric rivers in West Antarctica which is about 10 % of the total snowfall each year. We then examine a unique event that occurred in early February 2020, when three atmospheric rivers made landfall over West Antarctica in rapid succession, leading to heavy snowfall and surface melt.
Benjamin E. Smith, Brooke Medley, Xavier Fettweis, Tyler Sutterley, Patrick Alexander, David Porter, and Marco Tedesco
The Cryosphere, 17, 789–808, https://doi.org/10.5194/tc-17-789-2023, https://doi.org/10.5194/tc-17-789-2023, 2023
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We use repeated satellite measurements of the height of the Greenland ice sheet to learn about how three computational models of snowfall, melt, and snow compaction represent actual changes in the ice sheet. We find that the models do a good job of estimating how the parts of the ice sheet near the coast have changed but that two of the models have trouble representing surface melt for the highest part of the ice sheet. This work provides suggestions for how to better model snowmelt.
Taryn E. Black and Ian Joughin
The Cryosphere, 17, 1–13, https://doi.org/10.5194/tc-17-1-2023, https://doi.org/10.5194/tc-17-1-2023, 2023
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The frontal positions of most ice-sheet-based glaciers in Greenland vary seasonally. On average, these glaciers begin retreating in May and begin advancing in October, and the difference between their most advanced and most retreated positions is 220 m. The timing may be related to the timing of melt on the ice sheet, and the seasonal length variation may be related to glacier speed. These seasonal variations can affect glacier behavior and, consequently, how much ice is lost from the ice sheet.
Brooke Medley, Thomas A. Neumann, H. Jay Zwally, Benjamin E. Smith, and C. Max Stevens
The Cryosphere, 16, 3971–4011, https://doi.org/10.5194/tc-16-3971-2022, https://doi.org/10.5194/tc-16-3971-2022, 2022
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Satellite altimeters measure the height or volume change over Earth's ice sheets, but in order to understand how that change translates into ice mass, we must account for various processes at the surface. Specifically, snowfall events generate large, transient increases in surface height, yet snow fall has a relatively low density, which means much of that height change is composed of air. This air signal must be removed from the observed height changes before we can assess ice mass change.
Sophie Goliber, Taryn Black, Ginny Catania, James M. Lea, Helene Olsen, Daniel Cheng, Suzanne Bevan, Anders Bjørk, Charlie Bunce, Stephen Brough, J. Rachel Carr, Tom Cowton, Alex Gardner, Dominik Fahrner, Emily Hill, Ian Joughin, Niels J. Korsgaard, Adrian Luckman, Twila Moon, Tavi Murray, Andrew Sole, Michael Wood, and Enze Zhang
The Cryosphere, 16, 3215–3233, https://doi.org/10.5194/tc-16-3215-2022, https://doi.org/10.5194/tc-16-3215-2022, 2022
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Terminus traces have been used to understand how Greenland's glaciers have changed over time; however, manual digitization is time-intensive, and a lack of coordination leads to duplication of efforts. We have compiled a dataset of over 39 000 terminus traces for 278 glaciers for scientific and machine learning applications. We also provide an overview of an updated version of the Google Earth Engine Digitization Tool (GEEDiT), which has been developed specifically for the Greenland Ice Sheet.
Taryn E. Black and Ian Joughin
The Cryosphere, 16, 807–824, https://doi.org/10.5194/tc-16-807-2022, https://doi.org/10.5194/tc-16-807-2022, 2022
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We used satellite images to create a comprehensive record of annual glacier change in northwest Greenland from 1972 through 2021. We found that nearly all glaciers in our study area have retreated and glacier retreat accelerated from around 1996. Comparing these results with climate data, we found that glacier retreat is most sensitive to water runoff and moderately sensitive to ocean temperatures. These can affect glacier fronts in several ways, so no process clearly dominates glacier retreat.
Daniel R. Shapero, Jessica A. Badgeley, Andrew O. Hoffman, and Ian R. Joughin
Geosci. Model Dev., 14, 4593–4616, https://doi.org/10.5194/gmd-14-4593-2021, https://doi.org/10.5194/gmd-14-4593-2021, 2021
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This paper describes a new software package called "icepack" for modeling the flow of ice sheets and glaciers. Glaciologists use tools like icepack to better understand how ice sheets flow, what role they have played in shaping Earth's climate, and how much sea level rise we can expect in the coming decades to centuries. The icepack package includes several innovations to help researchers describe and solve interesting glaciological problems and to experiment with the underlying model physics.
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.
Rupert Gladstone, Benjamin Galton-Fenzi, David Gwyther, Qin Zhou, Tore Hattermann, Chen Zhao, Lenneke Jong, Yuwei Xia, Xiaoran Guo, Konstantinos Petrakopoulos, Thomas Zwinger, Daniel Shapero, and John Moore
Geosci. Model Dev., 14, 889–905, https://doi.org/10.5194/gmd-14-889-2021, https://doi.org/10.5194/gmd-14-889-2021, 2021
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Retreat of the Antarctic ice sheet, and hence its contribution to sea level rise, is highly sensitive to melting of its floating ice shelves. This melt is caused by warm ocean currents coming into contact with the ice. Computer models used for future ice sheet projections are not able to realistically evolve these melt rates. We describe a new coupling framework to enable ice sheet and ocean computer models to interact, allowing projection of the evolution of melt and its impact on sea level.
John Erich Christian, Alexander A. Robel, Cristian Proistosescu, Gerard Roe, Michelle Koutnik, and Knut Christianson
The Cryosphere, 14, 2515–2535, https://doi.org/10.5194/tc-14-2515-2020, https://doi.org/10.5194/tc-14-2515-2020, 2020
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We use simple, physics-based models to compare how marine-terminating glaciers respond to changes at their marine margin vs. inland surface melt. Initial glacier retreat is more rapid for ocean changes than for inland changes, but in both cases, glaciers will continue responding for millennia. We analyze several implications of these differing pathways of change. In particular, natural ocean variability must be better understood to correctly identify the anthropogenic role in glacier retreat.
Andrew Bliss, Regine Hock, Gabriel Wolken, Erin Whorton, Caroline Aubry-Wake, Juliana Braun, Alessio Gusmeroli, Will Harrison, Andrew Hoffman, Anna Liljedahl, and Jing Zhang
Earth Syst. Sci. Data, 12, 403–427, https://doi.org/10.5194/essd-12-403-2020, https://doi.org/10.5194/essd-12-403-2020, 2020
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Extensive field observations were conducted in the Upper Susitna basin in central Alaska in 2012–2014. This paper describes the weather, glacier mass balance, snow cover, and soils of the basin. We found that temperatures over the glacier are cooler than over land at the same elevation. The glaciers have been losing mass faster in recent years than in the 1980s. Measurements of glacier mass change with traditional methods closely matched radar measurements.
Ian Joughin, David E. Shean, Benjamin E. Smith, and Dana Floricioiu
The Cryosphere, 14, 211–227, https://doi.org/10.5194/tc-14-211-2020, https://doi.org/10.5194/tc-14-211-2020, 2020
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Jakobshavn Isbræ, considered to be Greenland's fastest glacier, has varied its speed and thinned dramatically since the 1990s. Here we examine the glacier's behaviour over the last decade to better understand this behaviour. We find that when the floating ice (mélange) in front of the glacier freezes in place during the winter, it can control the glacier's speed and thinning rate. A recently colder ocean has strengthened this mélange, allowing the glacier to recoup some of its previous losses.
David A. Lilien, Ian Joughin, Benjamin Smith, and Noel Gourmelen
The Cryosphere, 13, 2817–2834, https://doi.org/10.5194/tc-13-2817-2019, https://doi.org/10.5194/tc-13-2817-2019, 2019
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We used a number of computer simulations to understand the recent retreat of a rapidly changing group of glaciers in West Antarctica. We found that significant melt underneath the floating extensions of the glaciers, driven by relatively warm ocean water at depth, was likely needed to cause the large retreat that has been observed. If melt continues around current rates, retreat is likely to continue through the coming century and extend beyond the present-day drainage area of these glaciers.
David E. Shean, Ian R. Joughin, Pierre Dutrieux, Benjamin E. Smith, and Etienne Berthier
The Cryosphere, 13, 2633–2656, https://doi.org/10.5194/tc-13-2633-2019, https://doi.org/10.5194/tc-13-2633-2019, 2019
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We produced an 8-year, high-resolution DEM record for Pine Island Glacier (PIG), a site of substantial Antarctic mass loss in recent decades. We developed methods to study the spatiotemporal evolution of ice shelf basal melting, which is responsible for ~ 60 % of PIG mass loss. We present shelf-wide basal melt rates and document relative melt rates for kilometer-scale basal channels and keels, offering new indirect observations of ice–ocean interaction beneath a vulnerable ice shelf.
Andrew O. Hoffman, Hans Christian Steen-Larsen, Knut Christianson, and Christine Hvidberg
Geosci. Instrum. Method. Data Syst., 8, 149–159, https://doi.org/10.5194/gi-8-149-2019, https://doi.org/10.5194/gi-8-149-2019, 2019
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We present the design considerations and deployment of an autonomous modular terrestrial rover for ice-sheet exploration that is inexpensive, easy to construct, and allows for instrumentation customization. The rover proved capable of driving over 20 km on a single charge with a drawbar pull of 250 N, which is sufficient to tow commercial ground-penetrating radars. Due to its low cost, low power requirements, and simple modular design, mass deployments of this rover design are practicable.
Ian M. Howat, Claire Porter, Benjamin E. Smith, Myoung-Jong Noh, and Paul Morin
The Cryosphere, 13, 665–674, https://doi.org/10.5194/tc-13-665-2019, https://doi.org/10.5194/tc-13-665-2019, 2019
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The Reference Elevation Model of Antarctica (REMA) is the first continental-scale terrain map at less than 10 m resolution, and the first with a time stamp, enabling measurements of elevation change. REMA is constructed from over 300 000 individual stereoscopic elevation models (DEMs) extracted from submeter-resolution satellite imagery. REMA is vertically registered to satellite altimetry, resulting in errors of less than 1 m over most of its area and relative uncertainties of decimeters.
Nicholas Holschuh, Knut Christianson, Howard Conway, Robert W. Jacobel, and Brian C. Welch
The Cryosphere, 12, 2821–2829, https://doi.org/10.5194/tc-12-2821-2018, https://doi.org/10.5194/tc-12-2821-2018, 2018
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Models of the Antarctic Sheet are tuned using observations of historic ice-sheet behavior, but we have few observations that tell us how inland ice behaved over the last few millennia. A 2 km tall volcano sitting under the ice sheet has left a record in the ice as it flows by, and that feature provides unique insight into the regional ice-flow history. It indicates that observed, rapid changes in West Antarctica flow dynamics have not affected the continental interior over the last 5700 years.
Ian Joughin, Ben E. Smith, and Ian Howat
The Cryosphere, 12, 2211–2227, https://doi.org/10.5194/tc-12-2211-2018, https://doi.org/10.5194/tc-12-2211-2018, 2018
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We describe several new ice velocity maps produced using Landsat 8 and Copernicus Sentinel 1A/B data. We focus on several sites where we analyse these data in conjunction with earlier data from this project, which extend back to the year 2000. In particular, we find that Jakobshavn Isbræ began slowing substantially in 2017. The growing duration of these records will allow more robust analyses of the processes controlling fast flow and how they are affected by climate and other forcings.
David A. Lilien, Ian Joughin, Benjamin Smith, and David E. Shean
The Cryosphere, 12, 1415–1431, https://doi.org/10.5194/tc-12-1415-2018, https://doi.org/10.5194/tc-12-1415-2018, 2018
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We used remotely sensed data and a numerical model to study the processes controlling the stability of two rapidly changing ice shelves in West Antarctica. Both these ice shelves have been losing mass since at least 1996, primarily as a result of ocean-forced melt. We find that this imbalance likely results from changes initiated around 1970 or earlier. Our results also show that the shelves’ differing speedup is controlled by the strength of their margins and their grounding-line positions.
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
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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.
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.
D. N. Goldberg, P. Heimbach, I. Joughin, and B. Smith
The Cryosphere, 9, 2429–2446, https://doi.org/10.5194/tc-9-2429-2015, https://doi.org/10.5194/tc-9-2429-2015, 2015
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We calibrate a time-dependent ice model through optimal fit to transient observations of surface elevation and velocity, a novel procedure in glaciology and in particular for an ice stream with a dynamic grounding line. We show this procedure gives a level of confidence in model projections that cannot be achieved through more commonly used glaciological data assimilation methods. We show that Smith Glacier is in a state of retreat regardless of climatic forcing for the next several decades.
I. M. Howat, C. Porter, M. J. Noh, B. E. Smith, and S. Jeong
The Cryosphere, 9, 103–108, https://doi.org/10.5194/tc-9-103-2015, https://doi.org/10.5194/tc-9-103-2015, 2015
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In the summer of 2011, a large crater appeared in the surface of the Greenland Ice Sheet. It formed when a subglacial lake, equivalent to 10,000 swimming pools, catastrophically drained in less than 14 days. This is the first direct evidence that surface meltwater that drains through cracks to the bed of the ice sheet can build up in subglacial lakes over long periods of time. The sudden drainage may have been due to more surface melting and an increase in meltwater reaching the bed.
R. T. W. L. Hurkmans, J. L. Bamber, C. H. Davis, I. R. Joughin, K. S. Khvorostovsky, B. S. Smith, and N. Schoen
The Cryosphere, 8, 1725–1740, https://doi.org/10.5194/tc-8-1725-2014, https://doi.org/10.5194/tc-8-1725-2014, 2014
I. M. Howat, A. Negrete, and B. E. Smith
The Cryosphere, 8, 1509–1518, https://doi.org/10.5194/tc-8-1509-2014, https://doi.org/10.5194/tc-8-1509-2014, 2014
B. Medley, I. Joughin, B. E. Smith, S. B. Das, E. J. Steig, H. Conway, S. Gogineni, C. Lewis, A. S. Criscitiello, J. R. McConnell, M. R. van den Broeke, J. T. M. Lenaerts, D. H. Bromwich, J. P. Nicolas, and C. Leuschen
The Cryosphere, 8, 1375–1392, https://doi.org/10.5194/tc-8-1375-2014, https://doi.org/10.5194/tc-8-1375-2014, 2014
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
Related subject area
Discipline: Glaciers | Subject: Subglacial Processes
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard
Geothermal heat source estimations through ice flow modelling at Mýrdalsjökull, Iceland
Impact of shallow sills on circulation regimes and submarine melting in glacial fjords
Differential impact of isolated topographic bumps on ice sheet flow and subglacial processes
Channelized, distributed, and disconnected: spatial structure and temporal evolution of the subglacial drainage under a valley glacier in the Yukon
Persistent, extensive channelized drainage modeled beneath Thwaites Glacier, West Antarctica
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
Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard
Quantification of seasonal and diurnal dynamics of subglacial channels using seismic observations on an Alpine glacier
Glaciohydraulic seismic tremors on an Alpine glacier
Airborne radionuclides and heavy metals in high Arctic terrestrial environment as the indicators of sources and transfers of contamination
Pervasive cold ice within a temperate glacier – implications for glacier thermal regimes, sediment transport and foreland geomorphology
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
Cited articles
Carter, S., Blankenship, D., Peters, M., Young, D., Holt, J., and Morse, D.:
Radar-based subglacial lake classification in Antarctica,
Geochem. Geophy. Geosy.,
8, 3, https://doi.org/10.1029/2006GC001408, 2007.
Chen, G.:
GPS kinematics positioning for airborne laser altimetry at Long Valley,
PhD thesis,
Mass. Inst. of Technol., Cambridge, 1998.
Christianson, K., Bushuk, M., Dutrieux, P., Dutrieux, P., Parizek, B. R., Joughin, I. R., Alley, R. B., Shean, D. E., Polv, Abrahamsen, E., Anadakrishnan, S., Heywood, K. J., Tae-Wan, K., Hoon, Lee, S., Nicholls, K., Stanton, T., Truffer, M., Webber, B. G. M., Jenkins, A., Jacobs, S., Bindschadler, R., and Holland, D. M.:
Sensitivity of Pine Island Glacier to observed ocean forcing,
Geophys. Res. Lett.,
43, 10817–10825, https://doi.org/10.1002/2016GL070500, 2016.
Fricker, H. A., Scambos, T., Bindshadler, R., and Padman, L.:
An Active Subglacial Water System in West Antarctica Mapped from Space,
Science,
315, 1544–1548, https://doi.org/10.1126/science.1136897, 2007.
Friedl, P., Weiser, F., Fluhrer, A., and Braun, M. H.:
Remote sensing of glacier and ice sheet grounding lines: A review,
Earth-Sci. Rev.,
201, 102948, https://doi.org/10.1016/j.earscirev.2019.102948, 2020.
Gray, L., Joughin, I., Tulaczyk, S., Spikes, V. B., Bindschadler, R., and Jezek, K.:
Evidence for subglacial water transport in the West Antarctic Ice Sheet through threedimensional satellite radar interferometry,
Geophys. Res. Lett.,
32, L03501, https://doi.org/10.1029/2004gl021387, 2005.
Haran, T., Bohlander, J., Scambos, T., Painter, T., and Fahnestock, M.:
MODIS Mosaic of Antarctica 2008–2009 (MOA2009) Image Map,
Version 1, Boulder, Colorado, USA, NASA National Snow and Ice Data Center Distributed Active Archive Center, https://doi.org/10.7265/N5KP8037, 2014.
Holschuh, N., Christianson, K., Paden, J., Alley, R. B., and Anandakrishnan, S.:
Linking postglacial landscapes to glacier dynamics using swath radar at Thwaites Glacier, Antarctica,
Geology,
48, 268–272, https://doi.org/10.1130/G46772.1, 2020.
Joughin, I.:
MEaSUREs Greenland Monthly Ice Sheet Velocity Mosaics from SAR and Landsat, Version 1,
NASA National Snow and Ice Data Center Distributed Active Archive Center, Boulder, Colorado, USA,
https://doi.org/10.5067/OPFQ9QDEUFFY, 2018, updated 2019.
Joughin, I., Tulaczyk, S., Bamber, J., Blankenship, D., Holt, J., Scambos, T., and Vaughan, D.:
Basal conditions for Pine Island and Thwaites Glaciers, West Antarctica, determined using satellite and airborne data,
J. Glaciol.,
55, 245–257, https://doi.org/10.3189/002214309788608705, 2009.
Joughin I., Smith, B., and Abdalati, W.:
Glaciological advances made with interferometric synthetic aperture radar,
J. Glaciol.,
56, 1026–1042, 2010.
Joughin, I., Smith, B. E., and Medley, B.:
Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica,
Science,
344, 6185, 735–738, https://doi.org/10.1126/science.1249055, 2014.
Moore, J., Gladstone, R., Zwinger, T., and Wolovick, M.:
Geoengineering polar glaciers to slow sea-level rise,
Nature,
555, 303–305, https://doi.org/10.1038/d41586-018-03036-4, 2018.
Oswald, G. K. A. and Robin, G. De Q.:
Lakes Beneath the Antarctic Ice Sheet,
Nature,
245, 251–254, 1973.
Press, W. H., Teukolsky, S. A., Vetterling, W. T., and Flannery, B. P.:
Numerical Recipes, 3rd edn.,
Cambridge Univ. Press, Cambridge, UK, 2007.
Rignot, E., Mouginot, J., Morlighem, M., Seroussi, H., and Scheuchl, B.:
Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011,
Geophys. Res. Lett.,
41, 3502–3509, https://doi.org/10.1002/2014GL060140, 2014.
Robin, G. De Q., Evans, S., and Bailey, J. T.: Interpretation of radio echo sounding in polar ice sheets, Philos. Trans. R. Soc. London, Ser. A, 265, 437–505, 1969.
Shapero, D., Badgeley J., and Hoffman, A.: icepack: glacier flow modeling with the finite element
method in Python, Zenado, https://doi.org/10.5281/zenodo.4318150, 2020.
Shreve, R. L.:
Movement of water in glaciers,
J. Glaciol.,
11, 205–214, 1972.
Siegfried, M. R., Fricker, H. A., Roberts, M., Scambos, T. A., and Tulaczlyk, S.:
A decade of West Antarctic subglacial lake interactions from combined ICESat and CryoSat-2 altimetry,
Geophy. Res. Lett.,
41, 3, 891–898, https://doi.org/10.1002/2013GL058616, 2014.
Siegfried, M. R., Fricker, H. A., Carter, S. P., and Tulaczlyk, S.:
Episodic ice velocity fluctuations triggered by a subglacial flood in West Antarctica,
Geophy. Res. Lett.,
43, 2640–2648, https://doi.org/10.1002/2016GL067758, 2016.
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.
Smith, B. E., Gourmelen, N., Huth, A., and Joughin, I.: Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica, The Cryosphere, 11, 451–467, https://doi.org/10.5194/tc-11-451-2017, 2017.
Wilson, T., Bevis, M., Smalley Jr., R., Dalziel, I., Kendrick, E., Konfal, S., Saddler, D., and Willlis, M.: Antarctica-POLENET GPS Network – LTHW-Lower Thwaites Glacier P.S., The GAGE Facility operated by UNAVCO, Inc., GPS/GNSS Observations Dataset, https://doi.org/10.7283/T5NK3C7D, 2009a.
Wilson, T., Bevis, M., Smalley Jr., R., Dalziel, I., Kendrick, E., Konfal, S., Saddler, D., abd Willlis, M.: Antarctica-POLENET GPS Network – UTHW-Up Thwaites Glacier P.S., The GAGE Facility operated by UNAVCO, Inc., GPS/GNSS Observations Dataset, https://doi.org/10.7283/T50P0XBC, 2009b.
Wingham, D. J., Siegert, M. J., Shepherd, A., and Muir, A.:
Rapid discharge connects Antarctic subglacial lakes,
Nature,
440, 1033–1036, 2006.
Short summary
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.
The West Antarctic Ice Sheet has long been considered geometrically prone to collapse, and...
