Articles | Volume 15, issue 12
https://doi.org/10.5194/tc-15-5409-2021
© Author(s) 2021. 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-15-5409-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
07 Dec 2021
Research article |
| 07 Dec 2021
| 07 Dec 2021
Generation and fate of basal meltwater during winter, western Greenland Ice Sheet
Department of Geosciences, Univ. of Montana, Missoula, MT 59812, USA
Toby Meierbachtol
Department of Geosciences, Univ. of Montana, Missoula, MT 59812, USA
Neil Humphrey
Geology and Geophysics, Univ. of Wyoming, Laramie, Wyoming 82071, USA
Jun Saito
Geology and Geophysics, Univ. of Wyoming, Laramie, Wyoming 82071, USA
Aidan Stansberry
Geology and Geophysics, Univ. of Wyoming, Laramie, Wyoming 82071, USA
Related authors
Alamgir Hossan, Andreas Colliander, Nicole-Jeanne Schlegel, Joel Harper, Lauren Andrews, Jana Kolassa, Julie Z. Miller, and Richard Cullather
EGUsphere, https://doi.org/10.5194/egusphere-2025-2681, https://doi.org/10.5194/egusphere-2025-2681, 2025
This preprint is open for discussion and under review for The Cryosphere (TC).
Short summary
Short summary
Microwave L-band radiometry offers a promising tool for estimating the total surface-to-subsurface liquid water amount (LWA) in the snow and firn in polar ice sheets. An accurate modelling of wet snow effective permittivity is a key to this. Here, we evaluated the performance of ten commonly used microwave dielectric mixing models for estimating LWA in the percolation zone of the Greenland Ice Sheet to help an appropriate choice of dielectric mixing model for LWA retrieval algorithms.
Alamgir Hossan, Andreas Colliander, Baptiste Vandecrux, Nicole-Jeanne Schlegel, Joel Harper, Shawn Marshall, and Julie Z. Miller
EGUsphere, https://doi.org/10.5194/egusphere-2024-2563, https://doi.org/10.5194/egusphere-2024-2563, 2024
Short summary
Short summary
We used L-band observations from the SMAP mission to quantify the surface and subsurface liquid water amounts (LWA) in the percolation zone of the Greenland ice sheet. The algorithm is described, and the validation results are provided. The results demonstrate the potential for creating an LWA data product across GrIS, which will advance our understanding of ice sheet physical processes for better projection of Greenland’s contribution to global sea level rise.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
Caitlyn Florentine, Joel Harper, Daniel Fagre, Johnnie Moore, and Erich Peitzsch
The Cryosphere, 12, 2109–2122, https://doi.org/10.5194/tc-12-2109-2018, https://doi.org/10.5194/tc-12-2109-2018, 2018
Joel Brown, Joel Harper, and Neil Humphrey
The Cryosphere, 11, 669–679, https://doi.org/10.5194/tc-11-669-2017, https://doi.org/10.5194/tc-11-669-2017, 2017
Short summary
Short summary
We use ground-penetrating radar surveys in conjunction with borehole depth and temperature data to estimate the liquid water content (wetness) of glacial ice in the ablation zone of an outlet glacier on the western side of the Greenland Ice Sheet. Our results show that the wetness of a warm basal ice layer is approximately 2.9 % to 4.6 % in our study region. This high level of wetness requires special attention when modelling ice dynamics or estimating ice thickness in the region.
Adam M. Clark, Daniel B. Fagre, Erich H. Peitzsch, Blase A. Reardon, and Joel T. Harper
Earth Syst. Sci. Data, 9, 47–61, https://doi.org/10.5194/essd-9-47-2017, https://doi.org/10.5194/essd-9-47-2017, 2017
Short summary
Short summary
Most of the alpine glaciers in the world are shrinking. Because of the impact glaciers have on watershed hydrology, the US Geological Survey began a surface mass balance measurement program on Sperry Glacier in Glacier National Park, Montana, USA, in 2005. Between then and 2015 the USGS employed standard methods to estimate the mass changes across the surface of the glacier. During this 11-year period, Sperry Glacier had a cumulative mean mass balance loss of 4.37 m of water equivalent.
P. Kuipers Munneke, S. R. M. Ligtenberg, B. P. Y. Noël, I. M. Howat, J. E. Box, E. Mosley-Thompson, J. R. McConnell, K. Steffen, J. T. Harper, S. B. Das, and M. R. van den Broeke
The Cryosphere, 9, 2009–2025, https://doi.org/10.5194/tc-9-2009-2015, https://doi.org/10.5194/tc-9-2009-2015, 2015
Short summary
Short summary
The snow layer on top of the Greenland Ice Sheet is changing: it is thickening in the high and cold interior due to increased snowfall, while it is thinning around the margins. The marginal thinning is caused by compaction, and by more melt.
This knowledge is important: there are satellites that measure volume change of the ice sheet. It can be caused by increased ice discharge, or by compaction of the snow layer. Here, we quantify the latter, so that we can translate volume to mass change.
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
Short summary
Short summary
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.
Alamgir Hossan, Andreas Colliander, Nicole-Jeanne Schlegel, Joel Harper, Lauren Andrews, Jana Kolassa, Julie Z. Miller, and Richard Cullather
EGUsphere, https://doi.org/10.5194/egusphere-2025-2681, https://doi.org/10.5194/egusphere-2025-2681, 2025
This preprint is open for discussion and under review for The Cryosphere (TC).
Short summary
Short summary
Microwave L-band radiometry offers a promising tool for estimating the total surface-to-subsurface liquid water amount (LWA) in the snow and firn in polar ice sheets. An accurate modelling of wet snow effective permittivity is a key to this. Here, we evaluated the performance of ten commonly used microwave dielectric mixing models for estimating LWA in the percolation zone of the Greenland Ice Sheet to help an appropriate choice of dielectric mixing model for LWA retrieval algorithms.
Alamgir Hossan, Andreas Colliander, Baptiste Vandecrux, Nicole-Jeanne Schlegel, Joel Harper, Shawn Marshall, and Julie Z. Miller
EGUsphere, https://doi.org/10.5194/egusphere-2024-2563, https://doi.org/10.5194/egusphere-2024-2563, 2024
Short summary
Short summary
We used L-band observations from the SMAP mission to quantify the surface and subsurface liquid water amounts (LWA) in the percolation zone of the Greenland ice sheet. The algorithm is described, and the validation results are provided. The results demonstrate the potential for creating an LWA data product across GrIS, which will advance our understanding of ice sheet physical processes for better projection of Greenland’s contribution to global sea level rise.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
Caitlyn Florentine, Joel Harper, Daniel Fagre, Johnnie Moore, and Erich Peitzsch
The Cryosphere, 12, 2109–2122, https://doi.org/10.5194/tc-12-2109-2018, https://doi.org/10.5194/tc-12-2109-2018, 2018
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
Short summary
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.
Joel Brown, Joel Harper, and Neil Humphrey
The Cryosphere, 11, 669–679, https://doi.org/10.5194/tc-11-669-2017, https://doi.org/10.5194/tc-11-669-2017, 2017
Short summary
Short summary
We use ground-penetrating radar surveys in conjunction with borehole depth and temperature data to estimate the liquid water content (wetness) of glacial ice in the ablation zone of an outlet glacier on the western side of the Greenland Ice Sheet. Our results show that the wetness of a warm basal ice layer is approximately 2.9 % to 4.6 % in our study region. This high level of wetness requires special attention when modelling ice dynamics or estimating ice thickness in the region.
Adam M. Clark, Daniel B. Fagre, Erich H. Peitzsch, Blase A. Reardon, and Joel T. Harper
Earth Syst. Sci. Data, 9, 47–61, https://doi.org/10.5194/essd-9-47-2017, https://doi.org/10.5194/essd-9-47-2017, 2017
Short summary
Short summary
Most of the alpine glaciers in the world are shrinking. Because of the impact glaciers have on watershed hydrology, the US Geological Survey began a surface mass balance measurement program on Sperry Glacier in Glacier National Park, Montana, USA, in 2005. Between then and 2015 the USGS employed standard methods to estimate the mass changes across the surface of the glacier. During this 11-year period, Sperry Glacier had a cumulative mean mass balance loss of 4.37 m of water equivalent.
P. Kuipers Munneke, S. R. M. Ligtenberg, B. P. Y. Noël, I. M. Howat, J. E. Box, E. Mosley-Thompson, J. R. McConnell, K. Steffen, J. T. Harper, S. B. Das, and M. R. van den Broeke
The Cryosphere, 9, 2009–2025, https://doi.org/10.5194/tc-9-2009-2015, https://doi.org/10.5194/tc-9-2009-2015, 2015
Short summary
Short summary
The snow layer on top of the Greenland Ice Sheet is changing: it is thickening in the high and cold interior due to increased snowfall, while it is thinning around the margins. The marginal thinning is caused by compaction, and by more melt.
This knowledge is important: there are satellites that measure volume change of the ice sheet. It can be caused by increased ice discharge, or by compaction of the snow layer. Here, we quantify the latter, so that we can translate volume to mass change.
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
Short summary
Short summary
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
Discipline: Ice sheets | Subject: Greenland
Brief communication: Storstrømmen Glacier, northeastern Greenland, primed for end-of-decade surge
Historically consistent mass loss projections of the Greenland ice sheet
A comparison of supraglacial meltwater features throughout contrasting melt seasons: southwest Greenland
Enhanced MOIDS-derived ice physical properties within CoLM revealing bare ice-snow-albedo feedback over Greenland
Ice speed of a Greenlandic tidewater glacier modulated by tide, melt, and rain
Seasonal and interannual variability of freshwater sources for Greenland's fjords
A topographically controlled tipping point for complete Greenland ice sheet melt
Projections of precipitation and temperatures in Greenland and the impact of spatially uniform anomalies on the evolution of the ice sheet
Impacts of differing melt regimes on satellite radar waveforms and elevation retrievals
The future of Upernavik Isstrøm through the ISMIP6 framework: sensitivity analysis and Bayesian calibration of ensemble prediction
Firn seismic anisotropy in the Northeast Greenland Ice Stream from ambient-noise surface waves
Factors influencing lake surface water temperature variability in West Greenland and the role of the ice sheet
First results of the polar regional climate model RACMO2.4
Advancing interpretation of incoherent scattering in ice penetrating radar data used for ice core site selection
Calving front monitoring at a subseasonal resolution: a deep learning application for Greenland glaciers
Modeled Greenland Ice Sheet evolution constrained by ice-core-derived Holocene elevation histories
Bias in modeled Greenland ice sheet melt revealed by ASCAT
Mapping the vertical heterogeneity of Greenland's firn from 2011–2019 using airborne radar and laser altimetry
Subglacial valleys preserved in the highlands of south and east Greenland record restricted ice extent during past warmer climates
Coupling MAR (Modèle Atmosphérique Régional) with PISM (Parallel Ice Sheet Model) mitigates the positive melt–elevation feedback
Cloud- and ice-albedo feedbacks drive greater Greenland Ice Sheet sensitivity to warming in CMIP6 than in CMIP5
Evaluating different geothermal heat-flow maps as basal boundary conditions during spin-up of the Greenland ice sheet
Seasonal evolution of the supraglacial drainage network at Humboldt Glacier, northern Greenland, between 2016 and 2020
Choice of observation type affects Bayesian calibration of Greenland Ice Sheet model simulations
Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet
Precursor of disintegration of Greenland's largest floating ice tongue
An evaluation of a physics-based firn model and a semi-empirical firn model across the Greenland Ice Sheet (1980–2020)
Subglacial lake activity beneath the ablation zone of the Greenland Ice Sheet
The control of short-term ice mélange weakening episodes on calving activity at major Greenland outlet glaciers
Weekly to monthly terminus variability of Greenland's marine-terminating outlet glaciers
The contribution of Humboldt Glacier, northern Greenland, to sea-level rise through 2100 constrained by recent observations of speedup and retreat
Observed mechanism for sustained glacier retreat and acceleration in response to ocean warming around Greenland
Assessing bare-ice albedo simulated by MAR over the Greenland ice sheet (2000–2021) and implications for meltwater production estimates
Drill-site selection for cosmogenic-nuclide exposure dating of the bed of the Greenland Ice Sheet
A new Level 4 multi-sensor ice surface temperature product for the Greenland Ice Sheet
High-resolution imaging of supraglacial hydrological features on the Greenland Ice Sheet with NASA's Airborne Topographic Mapper (ATM) instrument suite
The impact of climate oscillations on the surface energy budget over the Greenland Ice Sheet in a changing climate
GBaTSv2: a revised synthesis of the likely basal thermal state of the Greenland Ice Sheet
Unravelling the long-term, locally heterogenous response of Greenland glaciers observed in archival photography
Simulating the Holocene deglaciation across a marine-terminating portion of southwestern Greenland in response to marine and atmospheric forcings
Comparison of ice dynamics using full-Stokes and Blatter–Pattyn approximation: application to the Northeast Greenland Ice Stream
Melt probabilities and surface temperature trends on the Greenland ice sheet using a Gaussian mixture model
Modelling the effect of submarine iceberg melting on glacier-adjacent water properties
Multi-decadal retreat of marine-terminating outlet glaciers in northwest and central-west Greenland
Sources of uncertainty in Greenland surface mass balance in the 21st century
Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
Brief communication: A roadmap towards credible projections of ice sheet contribution to sea level
Automated detection and analysis of surface calving waves with a terrestrial radar interferometer at the front of Eqip Sermia, Greenland
Modeling the Greenland englacial stratigraphy
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model
Jonas K. Andersen, Rasmus P. Meyer, Flora S. Huiban, Mads L. Dømgaard, Romain Millan, and Anders A. Bjørk
The Cryosphere, 19, 1717–1724, https://doi.org/10.5194/tc-19-1717-2025, https://doi.org/10.5194/tc-19-1717-2025, 2025
Short summary
Short summary
Storstrømmen Glacier in northeastern Greenland goes through cycles of sudden flow speed-ups (known as surges) followed by long quiet phases. It is currently in its quiet phase, but recent measurements suggest it may be nearing conditions for a new surge, possibly between 2027 and 2040. We also observed several lake drainages that caused brief increases in glacier flow but did not trigger a surge. Continued monitoring is essential to understand how these processes influence glacier behavior.
Charlotte Rahlves, Heiko Goelzer, Andreas Born, and Petra M. Langebroek
The Cryosphere, 19, 1205–1220, https://doi.org/10.5194/tc-19-1205-2025, https://doi.org/10.5194/tc-19-1205-2025, 2025
Short summary
Short summary
Mass loss from the Greenland ice sheet significantly contributes to rising sea levels, threatening coastal communities globally. To improve future sea-level projections, we simulated ice sheet behavior until 2100, initializing the model with observed geometry and using various climate models. Predictions indicate a sea-level rise of 32 to 228 mm by 2100, with climate model uncertainty being the main source of variability in projections.
Emily Glen, Amber Leeson, Alison F. Banwell, Jennifer Maddalena, Diarmuid Corr, Olivia Atkins, Brice Noël, and Malcolm McMillan
The Cryosphere, 19, 1047–1066, https://doi.org/10.5194/tc-19-1047-2025, https://doi.org/10.5194/tc-19-1047-2025, 2025
Short summary
Short summary
We compare surface meltwater features from optical satellite imagery in the Russell–Leverett glacier catchment during high (2019) and low (2018) melt years. In the high melt year, features appear at higher elevations, meltwater systems are more connected, small lakes are more frequent, and slush is more widespread. These findings provide insights into how a warming climate, where high melt years become common, could alter meltwater distribution and dynamics on the Greenland Ice Sheet.
Shuyang Guo, Yongjiu Dai, Hua Yuan, and Hongbin Liang
EGUsphere, https://doi.org/10.5194/egusphere-2025-230, https://doi.org/10.5194/egusphere-2025-230, 2025
Short summary
Short summary
The Snow, Ice, and Aerosol Radiation Model Version 4 has only been used to evaluate bare ice albedo in land surface models, with necessary ice property data lacking quality control. We integrated this model into our land surface model and improved bare ice properties using quality-controlled satellite data. Our findings show regional warming and reduced snow cover in Greenland’s bare ice region, driven by changes in bare ice properties through the bare ice-snow-albedo feedback.
Shin Sugiyama, Shun Tsutaki, Daiki Sakakibara, Izumi Asaji, Ken Kondo, Yefan Wang, Evgeny Podolskiy, Guillaume Jouvet, and Martin Funk
The Cryosphere, 19, 525–540, https://doi.org/10.5194/tc-19-525-2025, https://doi.org/10.5194/tc-19-525-2025, 2025
Short summary
Short summary
We report flow speed variations near the front of a tidewater glacier in Greenland. Ice flow near the glacier front is crucial for the mass loss of the Greenland ice sheet, but in situ data are hard to obtain. Our unique in situ GPS data revealed fine details of short-term speed variations associated with melting, ocean tides, and rain. The results are important for understanding the response of tidewater glaciers to changing environments, such as warming, more frequent rain, and ice thinning.
Anneke Louise Vries, Willem Jan van de Berg, Brice Noël, Lorenz Meire, and Michiel R. van den Broeke
EGUsphere, https://doi.org/10.5194/egusphere-2024-3735, https://doi.org/10.5194/egusphere-2024-3735, 2025
Short summary
Short summary
Freshwater enters Greenland's fjords from various sources. Solid ice discharge dominates freshwater input into fjords in the southeast and northwest. In contrast, in the southwest, runoff from the ice sheet and tundra are most significant. Seasonally resolved data revealed that fjord precipitation and tundra runoff contribute up to 11 % and 35 % of the total freshwater influx, respectively. Our results provide valuable input for ocean models and for researchers studying fjord ecosystems.
Michele Petrini, Meike D. W. Scherrenberg, Laura Muntjewerf, Miren Vizcaino, Raymond Sellevold, Gunter R. Leguy, William H. Lipscomb, and Heiko Goelzer
The Cryosphere, 19, 63–81, https://doi.org/10.5194/tc-19-63-2025, https://doi.org/10.5194/tc-19-63-2025, 2025
Short summary
Short summary
Anthropogenic warming is causing accelerated Greenland ice sheet melt. Here, we use a computer model to understand how prolonged warming and ice melt could threaten ice sheet stability. We find a threshold beyond which Greenland will lose more than 80 % of its ice over several thousand years, due to the interaction of surface and solid-Earth processes. Nearly complete Greenland ice sheet melt occurs when the ice margin disconnects from a region of high elevation in western Greenland.
Nils Bochow, Anna Poltronieri, and Niklas Boers
The Cryosphere, 18, 5825–5863, https://doi.org/10.5194/tc-18-5825-2024, https://doi.org/10.5194/tc-18-5825-2024, 2024
Short summary
Short summary
Using the latest climate models, we update the understanding of how the Greenland ice sheet responds to climate changes. We found that precipitation and temperature changes in Greenland vary across different regions. Our findings suggest that using uniform estimates for temperature and precipitation for modelling the response of the ice sheet can overestimate ice loss in Greenland. Therefore, this study highlights the need for spatially resolved data in predicting the ice sheet's future.
Alexander C. Ronan, Robert L. Hawley, and Jonathan W. Chipman
The Cryosphere, 18, 5673–5683, https://doi.org/10.5194/tc-18-5673-2024, https://doi.org/10.5194/tc-18-5673-2024, 2024
Short summary
Short summary
We generate a 2010–2021 time series of CryoSat-2 waveform shape metrics on the Greenland Ice Sheet, and we compare it to CryoSat-2 elevation data to investigate the reliability of two algorithms used to derive elevations from the SIRAL radar altimeter. Retracked elevations are found to depend on a waveform's leading-edge width in the dry-snow zone. The study indicates that retracking algorithms must consider significant climate events and snow conditions when assessing elevation change.
Eliot Jager, Fabien Gillet-Chaulet, Nicolas Champollion, Romain Millan, Heiko Goelzer, and Jérémie Mouginot
The Cryosphere, 18, 5519–5550, https://doi.org/10.5194/tc-18-5519-2024, https://doi.org/10.5194/tc-18-5519-2024, 2024
Short summary
Short summary
Inspired by a previous intercomparison framework, our study better constrains uncertainties in glacier evolution using an innovative method to validate Bayesian calibration. Upernavik Isstrøm, one of Greenland's largest glaciers, has lost significant mass since 1985. By integrating observational data, climate models, human emissions, and internal model parameters, we project its evolution until 2100. We show that future human emissions are the main source of uncertainty in 2100, making up half.
Emma Pearce, Dimitri Zigone, Coen Hofstede, Andreas Fichtner, Joachim Rimpot, Sune Olander Rasmussen, Johannes Freitag, and Olaf Eisen
The Cryosphere, 18, 4917–4932, https://doi.org/10.5194/tc-18-4917-2024, https://doi.org/10.5194/tc-18-4917-2024, 2024
Short summary
Short summary
Our study near EastGRIP camp in Greenland shows varying firn properties by direction (crucial for studying ice stream stability, structure, surface mass balance, and past climate conditions). We used dispersion curve analysis of Love and Rayleigh waves to show firn is nonuniform along and across the flow of an ice stream due to wind patterns, seasonal variability, and the proximity to the edge of the ice stream. This method better informs firn structure, advancing ice stream understanding.
Laura Carrea, Christopher J. Merchant, Richard I. Woolway, and Niall McCarroll
EGUsphere, https://doi.org/10.5194/egusphere-2024-2926, https://doi.org/10.5194/egusphere-2024-2926, 2024
Short summary
Short summary
Lakes in Greenland serve as sentinel of climate change. Satellites can be used to monitor water temperature and ice. Using 28 years measurements from satellite, we conclude that lakes are overall warmer than previously thought. The lakes connected to the ice sheet are cooler than the rest because of cold glacial meltwater inflow. Change in water temperature can impact light availability, nutrient cycling, and oxygen levels crucial for lake ecosystem but can also have influence on the ice sheet.
Christiaan T. van Dalum, Willem Jan van de Berg, Srinidhi N. Gadde, Maurice van Tiggelen, Tijmen van der Drift, Erik van Meijgaard, Lambertus H. van Ulft, and Michiel R. van den Broeke
The Cryosphere, 18, 4065–4088, https://doi.org/10.5194/tc-18-4065-2024, https://doi.org/10.5194/tc-18-4065-2024, 2024
Short summary
Short summary
We present a new version of the polar Regional Atmospheric Climate Model (RACMO), version 2.4p1, and show first results for Greenland, Antarctica and the Arctic. We provide an overview of all changes and investigate the impact that they have on the climate of polar regions. By comparing the results with observations and the output from the previous model version, we show that the model performs well regarding the surface mass balance of the ice sheets and near-surface climate.
Ellen Lucinda Mutter and Nicholas Holschuh
EGUsphere, https://doi.org/10.5194/egusphere-2024-2450, https://doi.org/10.5194/egusphere-2024-2450, 2024
Short summary
Short summary
“Ice Penetrating Radar” is a technology that lets us see through ice sheets, capturing their organized, layered structure. But near the ice bottom, radar data are much more complicated, with signals that are disordered and often ignored. Here, we work to better understand these complex signals by comparing radar data to measurements of ice structure from ice cores. We show these signals reflect structural changes in the ice itself, and can inform our search for ancient climate records.
Erik Loebel, Mirko Scheinert, Martin Horwath, Angelika Humbert, Julia Sohn, Konrad Heidler, Charlotte Liebezeit, and Xiao Xiang Zhu
The Cryosphere, 18, 3315–3332, https://doi.org/10.5194/tc-18-3315-2024, https://doi.org/10.5194/tc-18-3315-2024, 2024
Short summary
Short summary
Comprehensive datasets of calving-front changes are essential for studying and modeling outlet glaciers. Current records are limited in temporal resolution due to manual delineation. We use deep learning to automatically delineate calving fronts for 23 glaciers in Greenland. Resulting time series resolve long-term, seasonal, and subseasonal patterns. We discuss the implications of our results and provide the cryosphere community with a data product and an implementation of our processing system.
Mikkel Langgaard Lauritzen, Anne Munck Solgaard, Nicholas Mossor Rathmann, Bo Møllesøe Vinther, Aslak Grindsted, Brice Noël, Guðfinna Aðalgeirsdóttir, and Christine Schøtt Hvidberg
EGUsphere, https://doi.org/10.5194/egusphere-2024-2223, https://doi.org/10.5194/egusphere-2024-2223, 2024
Short summary
Short summary
We study the Holocene period, which started about 11,700 years ago, through 841 computer simulations to better understand the history of the Greenland Ice Sheet. We accurately match historical surface elevation records, verifying our model. The simulations show that an ice bridge that used to connect the Greenland ice sheet to Canada collapsed around 4,900 years ago and still influences the ice sheet. Over the past 500 years, the Greenland ice sheet has contributed 12 millimeters to sea levels.
Anna Puggaard, Nicolaj Hansen, Ruth Mottram, Thomas Nagler, Stefan Scheiblauer, Sebastian B. Simonsen, Louise S. Sørensen, Jan Wuite, and Anne M. Solgaard
EGUsphere, https://doi.org/10.5194/egusphere-2024-1108, https://doi.org/10.5194/egusphere-2024-1108, 2024
Short summary
Short summary
Regional climate models are currently the only source for assessing the melt volume on a global scale of the Greenland Ice Sheet. This study compares the modeled melt volume with observations from weather stations and melt extent observed from ASCAT to assess the performance of the models. It highlights the importance of critically evaluating model outputs with high-quality satellite measurements to improve the understanding of variability among models.
Anja Rutishauser, Kirk M. Scanlan, Baptiste Vandecrux, Nanna B. Karlsson, Nicolas Jullien, Andreas P. Ahlstrøm, Robert S. Fausto, and Penelope How
The Cryosphere, 18, 2455–2472, https://doi.org/10.5194/tc-18-2455-2024, https://doi.org/10.5194/tc-18-2455-2024, 2024
Short summary
Short summary
The Greenland Ice Sheet interior is covered by a layer of firn, which is important for surface meltwater runoff and contributions to global sea-level rise. Here, we combine airborne radar sounding and laser altimetry measurements to delineate vertically homogeneous and heterogeneous firn. Our results reveal changes in firn between 2011–2019, aligning well with known climatic events. This approach can be used to outline firn areas primed for significantly changing future meltwater runoff.
Guy J. G. Paxman, Stewart S. R. Jamieson, Aisling M. Dolan, and Michael J. Bentley
The Cryosphere, 18, 1467–1493, https://doi.org/10.5194/tc-18-1467-2024, https://doi.org/10.5194/tc-18-1467-2024, 2024
Short summary
Short summary
This study uses airborne radar data and satellite imagery to map mountainous topography hidden beneath the Greenland Ice Sheet. We find that the landscape records the former extent and configuration of ice masses that were restricted to areas of high topography. Computer models of ice flow indicate that valley glaciers eroded this landscape millions of years ago when local air temperatures were at least 4 °C higher than today and Greenland’s ice volume was < 10 % of that of the modern ice sheet.
Alison Delhasse, Johanna Beckmann, Christoph Kittel, and Xavier Fettweis
The Cryosphere, 18, 633–651, https://doi.org/10.5194/tc-18-633-2024, https://doi.org/10.5194/tc-18-633-2024, 2024
Short summary
Short summary
Aiming to study the long-term influence of an extremely warm climate in the Greenland Ice Sheet contribution to sea level rise, a new regional atmosphere–ice sheet model setup was established. The coupling, explicitly considering the melt–elevation feedback, is compared to an offline method to consider this feedback. We highlight mitigation of the feedback due to local changes in atmospheric circulation with changes in surface topography, making the offline correction invalid on the margins.
Idunn Aamnes Mostue, Stefan Hofer, Trude Storelvmo, and Xavier Fettweis
The Cryosphere, 18, 475–488, https://doi.org/10.5194/tc-18-475-2024, https://doi.org/10.5194/tc-18-475-2024, 2024
Short summary
Short summary
The latest generation of climate models (Coupled Model Intercomparison Project Phase 6 – CMIP6) warm more over Greenland and the Arctic and thus also project a larger mass loss from the Greenland Ice Sheet (GrIS) compared to the previous generation of climate models (CMIP5). Our work suggests for the first time that part of the greater mass loss in CMIP6 over the GrIS is driven by a difference in the surface mass balance sensitivity from a change in cloud representation in the CMIP6 models.
Tong Zhang, William Colgan, Agnes Wansing, Anja Løkkegaard, Gunter Leguy, William H. Lipscomb, and Cunde Xiao
The Cryosphere, 18, 387–402, https://doi.org/10.5194/tc-18-387-2024, https://doi.org/10.5194/tc-18-387-2024, 2024
Short summary
Short summary
The geothermal heat flux determines how much heat enters from beneath the ice sheet, and thus impacts the temperature and the flow of the ice sheet. In this study we investigate how much geothermal heat flux impacts the initialization of the Greenland ice sheet. We use the Community Ice Sheet Model with two different initialization methods. We find a non-trivial influence of the choice of heat flow boundary conditions on the ice sheet initializations for further designs of ice sheet modeling.
Lauren D. Rawlins, David M. Rippin, Andrew J. Sole, Stephen J. Livingstone, and Kang Yang
The Cryosphere, 17, 4729–4750, https://doi.org/10.5194/tc-17-4729-2023, https://doi.org/10.5194/tc-17-4729-2023, 2023
Short summary
Short summary
We map and quantify surface rivers and lakes at Humboldt Glacier to examine seasonal evolution and provide new insights of network configuration and behaviour. A widespread supraglacial drainage network exists, expanding up the glacier as seasonal runoff increases. Large interannual variability affects the areal extent of this network, controlled by high- vs. low-melt years, with late summer network persistence likely preconditioning the surface for earlier drainage activity the following year.
Denis Felikson, Sophie Nowicki, Isabel Nias, Beata Csatho, Anton Schenk, Michael J. Croteau, and Bryant Loomis
The Cryosphere, 17, 4661–4673, https://doi.org/10.5194/tc-17-4661-2023, https://doi.org/10.5194/tc-17-4661-2023, 2023
Short summary
Short summary
We narrow the spread in model simulations of the Greenland Ice Sheet using velocity change, dynamic thickness change, and mass change observations. We find that the type of observation chosen can lead to significantly different calibrated probability distributions. Further work is required to understand how to best calibrate ensembles of ice sheet simulations because this will improve probability distributions of projected sea-level rise, which is crucial for coastal planning and adaptation.
Johanna Beckmann and Ricarda Winkelmann
The Cryosphere, 17, 3083–3099, https://doi.org/10.5194/tc-17-3083-2023, https://doi.org/10.5194/tc-17-3083-2023, 2023
Short summary
Short summary
Over the past decade, Greenland has experienced several extreme melt events.
With progressing climate change, such extreme melt events can be expected to occur more frequently and potentially become more severe and persistent.
Strong melt events may considerably contribute to Greenland's mass loss, which in turn strongly determines future sea level rise. How important these extreme melt events could be in the future is assessed in this study for the first time.
Angelika Humbert, Veit Helm, Niklas Neckel, Ole Zeising, Martin Rückamp, Shfaqat Abbas Khan, Erik Loebel, Jörg Brauchle, Karsten Stebner, Dietmar Gross, Rabea Sondershaus, and Ralf Müller
The Cryosphere, 17, 2851–2870, https://doi.org/10.5194/tc-17-2851-2023, https://doi.org/10.5194/tc-17-2851-2023, 2023
Short summary
Short summary
The largest floating glacier mass in Greenland, the 79° N Glacier, is showing signs of instability. We investigate how crack formation at the glacier's calving front has changed over the last decades by using satellite imagery and airborne data. The calving front is about to lose contact to stabilizing ice islands. Simulations show that the glacier will accelerate as a result of this, leading to an increase in ice discharge of more than 5.1 % if its calving front retreats by 46 %.
Megan Thompson-Munson, Nander Wever, C. Max Stevens, Jan T. M. Lenaerts, and Brooke Medley
The Cryosphere, 17, 2185–2209, https://doi.org/10.5194/tc-17-2185-2023, https://doi.org/10.5194/tc-17-2185-2023, 2023
Short summary
Short summary
To better understand the Greenland Ice Sheet’s firn layer and its ability to buffer sea level rise by storing meltwater, we analyze firn density observations and output from two firn models. We find that both models, one physics-based and one semi-empirical, simulate realistic density and firn air content when compared to observations. The models differ in their representation of firn air content, highlighting the uncertainty in physical processes and the paucity of deep-firn measurements.
Yubin Fan, Chang-Qing Ke, Xiaoyi Shen, Yao Xiao, Stephen J. Livingstone, and Andrew J. Sole
The Cryosphere, 17, 1775–1786, https://doi.org/10.5194/tc-17-1775-2023, https://doi.org/10.5194/tc-17-1775-2023, 2023
Short summary
Short summary
We used the new-generation ICESat-2 altimeter to detect and monitor active subglacial lakes in unprecedented spatiotemporal detail. We created a new inventory of 18 active subglacial lakes as well as their elevation and volume changes during 2019–2020, which provides an improved understanding of how the Greenland subglacial water system operates and how these lakes are fed by water from the ice surface.
Adrien Wehrlé, Martin P. Lüthi, and Andreas Vieli
The Cryosphere, 17, 309–326, https://doi.org/10.5194/tc-17-309-2023, https://doi.org/10.5194/tc-17-309-2023, 2023
Short summary
Short summary
We characterized short-lived episodes of ice mélange weakening (IMW) at the front of three major Greenland outlet glaciers. Through a continuous detection at the front of Kangerdlugssuaq Glacier during the June-to-September period from 2018 to 2021, we found that 87 % of the IMW episodes occurred prior to a large-scale calving event. Using a simple model for ice mélange motion, we further characterized the IMW process as self-sustained through the existence of an IMW–calving feedback.
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
Short summary
Short summary
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.
Trevor R. Hillebrand, Matthew J. Hoffman, Mauro Perego, Stephen F. Price, and Ian M. Howat
The Cryosphere, 16, 4679–4700, https://doi.org/10.5194/tc-16-4679-2022, https://doi.org/10.5194/tc-16-4679-2022, 2022
Short summary
Short summary
We estimate that Humboldt Glacier, northern Greenland, will contribute 5.2–8.7 mm to global sea level in 2007–2100, using an ensemble of model simulations constrained by observations of glacier retreat and speedup. This is a significant fraction of the 40–140 mm from the whole Greenland Ice Sheet predicted by the recent ISMIP6 multi-model ensemble, suggesting that calibrating models against observed velocity changes could result in higher estimates of 21st century sea-level rise from Greenland.
Evan Carnahan, Ginny Catania, and Timothy C. Bartholomaus
The Cryosphere, 16, 4305–4317, https://doi.org/10.5194/tc-16-4305-2022, https://doi.org/10.5194/tc-16-4305-2022, 2022
Short summary
Short summary
The Greenland Ice Sheet primarily loses mass through increased ice discharge. We find changes in discharge from outlet glaciers are initiated by ocean warming, which causes a change in the balance of forces resisting gravity and leads to acceleration. Vulnerable conditions for sustained retreat and acceleration are predetermined by the glacier-fjord geometry and exist around Greenland, suggesting increases in ice discharge may be sustained into the future despite a pause in ocean warming.
Raf M. Antwerpen, Marco Tedesco, Xavier Fettweis, Patrick Alexander, and Willem Jan van de Berg
The Cryosphere, 16, 4185–4199, https://doi.org/10.5194/tc-16-4185-2022, https://doi.org/10.5194/tc-16-4185-2022, 2022
Short summary
Short summary
The ice on Greenland has been melting more rapidly over the last few years. Most of this melt comes from the exposure of ice when the overlying snow melts. This ice is darker than snow and absorbs more sunlight, leading to more melt. It remains challenging to accurately simulate the brightness of the ice. We show that the color of ice simulated by Modèle Atmosphérique Régional (MAR) is too bright. We then show that this means that MAR may underestimate how fast the Greenland ice is melting.
Jason P. Briner, Caleb K. Walcott, Joerg M. Schaefer, Nicolás E. Young, Joseph A. MacGregor, Kristin Poinar, Benjamin A. Keisling, Sridhar Anandakrishnan, Mary R. Albert, Tanner Kuhl, and Grant Boeckmann
The Cryosphere, 16, 3933–3948, https://doi.org/10.5194/tc-16-3933-2022, https://doi.org/10.5194/tc-16-3933-2022, 2022
Short summary
Short summary
The 7.4 m of sea level equivalent stored as Greenland ice is getting smaller every year. The uncertain trajectory of ice loss could be better understood with knowledge of the ice sheet's response to past climate change. Within the bedrock below the present-day ice sheet is an archive of past ice-sheet history. We analyze all available data from Greenland to create maps showing where on the ice sheet scientists can drill, using currently available drills, to obtain sub-ice materials.
Ioanna Karagali, Magnus Barfod Suhr, Ruth Mottram, Pia Nielsen-Englyst, Gorm Dybkjær, Darren Ghent, and Jacob L. Høyer
The Cryosphere, 16, 3703–3721, https://doi.org/10.5194/tc-16-3703-2022, https://doi.org/10.5194/tc-16-3703-2022, 2022
Short summary
Short summary
Ice surface temperature (IST) products were used to develop the first multi-sensor, gap-free Level 4 (L4) IST product of the Greenland Ice Sheet (GIS) for 2012, when a significant melt event occurred. For the melt season, mean IST was −15 to −1 °C, and almost the entire GIS experienced at least 1 to 5 melt days. Inclusion of the L4 IST to a surface mass budget (SMB) model improved simulated surface temperatures during the key onset of the melt season, where biases are typically large.
Michael Studinger, Serdar S. Manizade, Matthew A. Linkswiler, and James K. Yungel
The Cryosphere, 16, 3649–3668, https://doi.org/10.5194/tc-16-3649-2022, https://doi.org/10.5194/tc-16-3649-2022, 2022
Short summary
Short summary
The footprint density and high-resolution imagery of airborne surveys reveal details in supraglacial hydrological features that are currently not obtainable from spaceborne data. The accuracy and resolution of airborne measurements complement spaceborne measurements, can support calibration and validation of spaceborne methods, and provide information necessary for process studies of the hydrological system on ice sheets that currently cannot be achieved from spaceborne observations alone.
Tiago Silva, Jakob Abermann, Brice Noël, Sonika Shahi, Willem Jan van de Berg, and Wolfgang Schöner
The Cryosphere, 16, 3375–3391, https://doi.org/10.5194/tc-16-3375-2022, https://doi.org/10.5194/tc-16-3375-2022, 2022
Short summary
Short summary
To overcome internal climate variability, this study uses k-means clustering to combine NAO, GBI and IWV over the Greenland Ice Sheet (GrIS) and names the approach as the North Atlantic influence on Greenland (NAG). With the support of a polar-adapted RCM, spatio-temporal changes on SEB components within NAG phases are investigated. We report atmospheric warming and moistening across all NAG phases as well as large-scale and regional-scale contributions to GrIS mass loss and their interactions.
Joseph A. MacGregor, Winnie Chu, William T. Colgan, Mark A. Fahnestock, Denis Felikson, Nanna B. Karlsson, Sophie M. J. Nowicki, and Michael Studinger
The Cryosphere, 16, 3033–3049, https://doi.org/10.5194/tc-16-3033-2022, https://doi.org/10.5194/tc-16-3033-2022, 2022
Short summary
Short summary
Where the bottom of the Greenland Ice Sheet is frozen and where it is thawed is not well known, yet knowing this state is increasingly important to interpret modern changes in ice flow there. We produced a second synthesis of knowledge of the basal thermal state of the ice sheet using airborne and satellite observations and numerical models. About one-third of the ice sheet’s bed is likely thawed; two-fifths is likely frozen; and the remainder is too uncertain to specify.
Michael A. Cooper, Paulina Lewińska, William A. P. Smith, Edwin R. Hancock, Julian A. Dowdeswell, and David M. Rippin
The Cryosphere, 16, 2449–2470, https://doi.org/10.5194/tc-16-2449-2022, https://doi.org/10.5194/tc-16-2449-2022, 2022
Short summary
Short summary
Here we use old photographs gathered several decades ago to expand the temporal record of glacier change in part of East Greenland. This is important because the longer the record of past glacier change, the better we are at predicting future glacier behaviour. Our work also shows that despite all these glaciers retreating, the rate at which they do this varies markedly. It is therefore important to consider outlet glaciers from Greenland individually to take account of this differing behaviour.
Joshua K. Cuzzone, Nicolás E. Young, Mathieu Morlighem, Jason P. Briner, and Nicole-Jeanne Schlegel
The Cryosphere, 16, 2355–2372, https://doi.org/10.5194/tc-16-2355-2022, https://doi.org/10.5194/tc-16-2355-2022, 2022
Short summary
Short summary
We use an ice sheet model to determine what influenced the Greenland Ice Sheet to retreat across a portion of southwestern Greenland during the Holocene (about the last 12 000 years). Our simulations, constrained by observations from geologic markers, show that atmospheric warming and ice melt primarily caused the ice sheet to retreat rapidly across this domain. We find, however, that iceberg calving at the interface where the ice meets the ocean significantly influenced ice mass change.
Martin Rückamp, Thomas Kleiner, and Angelika Humbert
The Cryosphere, 16, 1675–1696, https://doi.org/10.5194/tc-16-1675-2022, https://doi.org/10.5194/tc-16-1675-2022, 2022
Short summary
Short summary
We present a comparative modelling study between the full-Stokes (FS) and Blatter–Pattyn (BP) approximation applied to the Northeast Greenland Ice Stream. Both stress regimes are implemented in one single ice sheet code to eliminate numerical issues. The simulations unveil minor differences in the upper ice stream but become considerable at the grounding line of the 79° North Glacier. Model differences are stronger for a power-law friction than a linear friction law.
Daniel Clarkson, Emma Eastoe, and Amber Leeson
The Cryosphere, 16, 1597–1607, https://doi.org/10.5194/tc-16-1597-2022, https://doi.org/10.5194/tc-16-1597-2022, 2022
Short summary
Short summary
The Greenland ice sheet has seen large amounts of melt in recent years, and accurately modelling temperatures is vital to understand how much of the ice sheet is melting. We estimate the probability of melt from ice surface temperature data to identify which areas of the ice sheet have experienced melt and estimate temperature quantiles. Our results suggest that for large areas of the ice sheet, melt has become more likely over the past 2 decades and high temperatures are also becoming warmer.
Benjamin Joseph Davison, Tom Cowton, Andrew Sole, Finlo Cottier, and Pete Nienow
The Cryosphere, 16, 1181–1196, https://doi.org/10.5194/tc-16-1181-2022, https://doi.org/10.5194/tc-16-1181-2022, 2022
Short summary
Short summary
The ocean is an important driver of Greenland glacier retreat. Icebergs influence ocean temperature in the vicinity of glaciers, which will affect glacier retreat rates, but the effect of icebergs on water temperature is poorly understood. In this study, we use a model to show that icebergs cause large changes to water properties next to Greenland's glaciers, which could influence ocean-driven glacier retreat around Greenland.
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
Short summary
Short summary
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.
Katharina M. Holube, Tobias Zolles, and Andreas Born
The Cryosphere, 16, 315–331, https://doi.org/10.5194/tc-16-315-2022, https://doi.org/10.5194/tc-16-315-2022, 2022
Short summary
Short summary
We simulated the surface mass balance of the Greenland Ice Sheet in the 21st century by forcing a snow model with the output of many Earth system models and four greenhouse gas emission scenarios. We quantify the contribution to uncertainty in surface mass balance of these two factors and the choice of parameters of the snow model. The results show that the differences between Earth system models are the main source of uncertainty. This effect is localised mostly near the equilibrium line.
David W. Ashmore, Douglas W. F. Mair, Jonathan E. Higham, Stephen Brough, James M. Lea, and Isabel J. Nias
The Cryosphere, 16, 219–236, https://doi.org/10.5194/tc-16-219-2022, https://doi.org/10.5194/tc-16-219-2022, 2022
Short summary
Short summary
In this paper we explore the use of a transferrable and flexible statistical technique to try and untangle the multiple influences on marine-terminating glacier dynamics, as measured from space. We decompose a satellite-derived ice velocity record into ranked sets of static maps and temporal coefficients. We present evidence that the approach can identify velocity variability mainly driven by changes in terminus position and velocity variation mainly driven by subglacial hydrological processes.
Andy Aschwanden, Timothy C. Bartholomaus, Douglas J. Brinkerhoff, and Martin Truffer
The Cryosphere, 15, 5705–5715, https://doi.org/10.5194/tc-15-5705-2021, https://doi.org/10.5194/tc-15-5705-2021, 2021
Short summary
Short summary
Estimating how much ice loss from Greenland and Antarctica will contribute to sea level rise is of critical societal importance. However, our analysis shows that recent efforts are not trustworthy because the models fail at reproducing contemporary ice melt. Here we present a roadmap towards making more credible estimates of ice sheet melt.
Adrien Wehrlé, Martin P. Lüthi, Andrea Walter, Guillaume Jouvet, and Andreas Vieli
The Cryosphere, 15, 5659–5674, https://doi.org/10.5194/tc-15-5659-2021, https://doi.org/10.5194/tc-15-5659-2021, 2021
Short summary
Short summary
We developed a novel automated method for the detection and the quantification of ocean waves generated by glacier calving. This method was applied to data recorded with a terrestrial radar interferometer at Eqip Sermia, Greenland. Results show a high calving activity at the glacier front sector ending in deep water linked with more frequent meltwater plumes. This suggests that rising subglacial meltwater plumes strongly affect glacier calving in deep water, but weakly in shallow water.
Andreas Born and Alexander Robinson
The Cryosphere, 15, 4539–4556, https://doi.org/10.5194/tc-15-4539-2021, https://doi.org/10.5194/tc-15-4539-2021, 2021
Short summary
Short summary
Ice penetrating radar reflections from the Greenland ice sheet are the best available record of past accumulation and how these layers have been deformed over time by the flow of ice. Direct simulations of this archive hold great promise for improving our models and for uncovering details of ice sheet dynamics that neither models nor data could achieve alone. We present the first three-dimensional ice sheet model that explicitly simulates individual layers of accumulation and how they deform.
Tamara Annina Gerber, Christine Schøtt Hvidberg, Sune Olander Rasmussen, Steven Franke, Giulia Sinnl, Aslak Grinsted, Daniela Jansen, and Dorthe Dahl-Jensen
The Cryosphere, 15, 3655–3679, https://doi.org/10.5194/tc-15-3655-2021, https://doi.org/10.5194/tc-15-3655-2021, 2021
Short summary
Short summary
We simulate the ice flow in the onset region of the Northeast Greenland Ice Stream to determine the source area and past accumulation rates of ice found in the EastGRIP ice core. This information is required to correct for bias in ice-core records introduced by the upstream flow effects. Our results reveal that the increasing accumulation rate with increasing upstream distance is predominantly responsible for the constant annual layer thicknesses observed in the upper 900 m of the ice core.
Cited articles
Abe, T. and Furuya, M.: Winter speed-up of quiescent surge-type glaciers in Yukon, Canada, The Cryosphere, 9, 1183–1190, https://doi.org/10.5194/tc-9-1183-2015, 2015.
Anderson, R. S., Hallet, B., Walder, J., and Aubry, B. F.: Observations in a cavity beneath Grinnell Glacier, Earth Surf. Process. Landf., 7, 63–70, https://doi.org/10.1002/esp.3290070108, 1982.
Andrews, L. C., Catania, G. A., Hoffman, M. J., Gulley, J. D., Lüthi, M.
P., Ryser, C., Hawley, R. L., and Neumann, T. A.: Direct observations of
evolving subglacial drainage beneath the Greenland Ice Sheet, Nature,
514, 80–83, https://doi.org/10.1038/nature13796, 2014.
Booth, A. D., Clark, R. A., Kulessa, B., Murray, T., Carter, J., Doyle, S., and Hubbard, A.: Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA) analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland, The Cryosphere, 6, 909–922, https://doi.org/10.5194/tc-6-909-2012, 2012.
Brinkerhoff, D. J., Meierbachtol, T. W., Johnson, J. V., and Harper, J. T.:
Sensitivity of the frozen-melted basal boundary to perturbations of basal
traction and geothermal heat flux: Isunnguata Sermia, western Greenland,
Ann. Glaciol., 52, 43–50, 2011.
Brown, J., Harper, J., and Humphrey, N.: Liquid water content in ice estimated through a full-depth ground radar profile and borehole measurements in western Greenland, The Cryosphere, 11, 669–679, https://doi.org/10.5194/tc-11-669-2017, 2017.
Chu, W., Schroeder, D. M., Seroussi, H., Creyts, T. T., Palmer, S. J., and Bell, R. E.: Extensive winter subglacial water storage beneath the Greenland Ice Sheet, Geophys. Res. Lett., 43, 12484–12492, https://doi.org/10.1002/2016GL071538, 2016.
Cuffey, K. M. and Paterson, W. S. B.: The physics of glaciers, 4th edn., Elsevier, Oxford,
2010.
Derkacheva, A., Mouginot, J., Millan, R., Maier, N., and Gillet-Chaulet, F.:
Data reduction using statistical and regression approaches for ice velocity
derived by Landsat-8, Sentinel-1 and Sentinel-2, Remote Sens., 2020,
1935, https://doi.org/10.3390/rs12121935, 2020.
Dow, C. F., Hubbard, A., Booth, A. D., Doyle, S. H., Gusmeroli, A., and
Kulessa, B.: Seismic evidence of mechanically weak sediments underlying
Russell Glacier, West Greenland, Ann. Glaciol., 54, 135–141,
https://doi.org/10.3189/2013AoG64A032, 2013.
Downs, J. Z., Johnson, J. V., Harper, J. T., Meierbachtol, T., and Werder, M.
A.: Dynamic hydraulic conductivity reconciles mismatch between modeled and
observed winter subglacial water pressure, J. Geophys. Res.-Earth Surf.,
123, 818–836, https://doi.org/10.1002/2017JF004522, 2018.
Fitzpatrick, A. A. W., Hubbard, A., Joughin, I., Quincey, D. J., Van As, D.,
Mikkelsen, A. P. B., Doyle, S. H., Hasholt, B., and Jones, G. A.: Ice flow
dynamics and surface meltwater flux at a land-terminating sector of the
Greenland ice sheet, J. Glaciol., 59, 687–696,
https://doi.org/10.3189/2013JoG12J143, 2013.
GRASS Development Team: Geographic Resources Analysis Support System
(GRASS), available at: https://grass.osgeo.org (last access: 14 April 2021), 2020.
Harper, J. T., Humphrey, N. F., Meierbachtol, T. W., Graly, J. A., and
Fischer, U. H.: Borehole measurements indicate hard bed conditions,
Kangerlussuaq sector, western Greenland Ice Sheet, J. Geophys. Res.-Earth
Surf., 122, 1–14, https://doi.org/10.1002/2017JF004201, 2017.
Harrington, J. A., Humphrey, N. F., and Harper, J. T.: Temperature
distribution and thermal anomalies along a flowline of the Greenland Ice
Sheet, Ann. Glaciol., 56, 98–104, https://doi.org/10.3189/2015AoG70A945, 2015.
Herring, T., King, R., and McClusky, S.: GAMIT/GLOBK Reference Manuals,
Release 10.4, Massachusetts Institute of Technology, Cambridge, MA, USA,
2010.
Hewitt, I. J.: Modelling distributed and channelized subglacial drainage:
The spacing of channels, J. Glaciol., 57, 302–314,
https://doi.org/10.3189/002214311796405951, 2011.
Hills, B.: Near-surface ice temperature measurements from Western Greenland, 2011–2017, Arctic Data Center [data set], https://doi.org/10.18739/A2QV3C418, 2018.
Hills, B. H., Harper, J. T., Humphrey, N. F., and Meierbachtol, T. W.:
Measured horizontal temperature gradients constrain heat transfer mechanisms
in Greenland ice, Geophys. Res. Lett., 44, 9778–9785,
https://doi.org/10.1002/2017GL074917, 2017.
Hills, B. H., Harper, J. T., Meierbachtol, T. W., Johnson, J. V., Humphrey, N. F., and Wright, P. J.: Processes influencing heat transfer in the near-surface ice of Greenland's ablation zone, The Cryosphere, 12, 3215–3227, https://doi.org/10.5194/tc-12-3215-2018, 2018.
Iken, A.: The effect of the subglacial water pressure on the sliding
velocity of a glacier in an idealized numerical model, J. Glaciol., 27,
407–421, https://doi.org/10.1017/S0022143000011448, 1981.
Iken, A. and Truffer, M.: The relationship between subglacial water pressure
and velocity of Findelengletscher, Switzerland, during its advance and
retreat, J. Glaciol., 43, 328–338, 1997.
Jaquet, O., Namar, R., Siegel, P., Harper, J., and Jansson, P.: Groundwater
flow modelling under transient ice sheet – conditions in Greenland, Swedish
Nucl. Fuel Waste Manag. Organ., SKB R-19-1, 1–123, 2019.
Joughin, I., Das, S. B., King, M. A., Smith, B. E., and Howat, I. M.:
Seasonal speedup along the flank of the Greenland Ice Sheet, Science, 320, 781–783, https://doi.org/10.1126/science.1153288, 2008.
Joughin, I., Smith, B. E., Howat, I. M., Scambos, T., and Moon, T.: Greenland
flow variability from ice-sheet-wide velocity mapping, J. Glaciol., 56,
415–430, https://doi.org/10.3189/002214310792447734, 2010.
Joughin, I., Smith, B. E., and Howat, I.: Greenland Ice Mapping Project: ice flow velocity variation at sub-monthly to decadal timescales, The Cryosphere, 12, 2211–2227, https://doi.org/10.5194/tc-12-2211-2018, 2018a.
Joughin, I., Smith, B., Howat, I., and Scambos, T.: MEaSUREs Greenland Ice
Sheet velocity map from InSAR data, Version 2, User Manual, National Snow and Ice Data Center (NSIDC), https://doi.org/10.5067/OC7B04ZM9G6Q, 2018b.
Kamb, B.: Glacier surge mechanism based on linked cavity configuration of
the basal water conduit system, J. Geophys. Res., 92, 9083–9100, 1987.
Kamb, B. and Echelmeyer, K.: Stress-gradient coupling in glacier flow: 1.
Longitudinal averaging of the influence of ice thickness and surface slope,
J. Glaciol., 32, 267–284, 1986.
Kulessa, B., Hubbard, A. L., Booth, A. D., Bougamont, M., Dow, C. F., Doyle,
S. H., Christoffersen, P., Lindbäck, K., Pettersson, R., Fitzpatrick, A.
A. W., and Jones, G. A.: Seismic evidence for complex sedimentary control of
Greenland Ice Sheet flow, Sci. Adv., 3, 1–9, https://doi.org/10.1126/sciadv.1603071,
2017.
Lemieux, J. M., Sudicky, E. A., Peltier, W. R., and Tarasov, L.: Dynamics of
groundwater recharge and seepage over the Canadian landscape during the
Wisconsinian glaciation, J. Geophys. Res.-Earth Surf., 113, 1–18,
https://doi.org/10.1029/2007JF000838, 2008.
Lüthi, M., Funk, M., Iken, A., Gogineni, S., and Truffer, M.: Mechanisms
of fast flow in Jakobshavn Isbræ, West Greenland: Part III. Measurements
of ice deformation, temperature and cross-borehole conductivity in boreholes
to the bedrock, J. Glaciol., 48, 369–385,
https://doi.org/10.3189/172756502781831322, 2002.
MacGregor, J. A., Fahnestock, M. A., Catania, G. A., Aschwanden, A., Clow,
G. D., Colgan, W. T., Gogineni, S. P., Morlighem, M., Nowicki, S. M. J.,
Paden, J. D., Price, S. F., and Seroussi, H.: A synthesis of the basal
thermal state of the Greenland Ice Sheet, J. Geophys. Res.-Earth Surf.,
121, 1328–1350, https://doi.org/10.1002/2015JF003803, 2016.
Maier, N.: Global Positioning System (GPS) positions and in situ ice deformation from borehole inclinometry measurements in Western Greenland, winter 2015–16, Arctic Data Center [data set], https://doi.org/10.18739/A2154DP90, 2019.
Maier, N., Humphrey, N., Harper, J., Meierbachtol. T., and Meierbachtol, T.:
Sliding dominates slow-flowing margin regions, Greenland Ice Sheet, Sci.
Adv., 5, eaaw5406, https://doi.org/10.1126/sciadv.aaw5406, 2019.
Meierbachtol, T.: Basal water pressure measured in boreholes drilled to the bed of Western Greenland: 2014–2017, Arctic Data Center [data set], https://doi.org/10.18739/A2VQ2SB3C, 2017.
Meierbachtol, T., Harper, J., and Humphrey, N.: Basal drainage system
response to increasing surface melt on the Greenland Ice Sheet, Science, 341, 777–779, https://doi.org/10.1126/science.1235905, 2013.
Meierbachtol, T., Harper, J., Johnson, J., Humphrey, N., and Brinkerhoff, D.:
Thermal boundary conditions on western Greenland: Observational constraints
and impacts on the modeled thermomechanical state, J. Geophys. Res.-Earth
Surf., 120, 623–636, https://doi.org/10.1002/2014JF003375, 2015.
Meierbachtol, T., Harper, J. T., Humphrey, N. F., and Wright, P.:
Mechanical forcing on water pressure in a hydrologically isolated reach
beneath Western Greenland's ablation zone, Ann. Glaciol., 57, 1–9,
https://doi.org/10.1017/aog.2016.5, 2016a.
Meierbachtol, T., Harper, J., and Johnson, J.: Force balance along
isunnguata Sermia, west Greenland, Front. Earth Sci., 4, 1–9,
https://doi.org/10.3389/feart.2016.00087, 2016b.
Moon, T., Joughin, I., Smith, B., Van Den Broeke, M. R., Van De Berg, W. J.,
Noël, B., and Usher, M.: Distinct patterns of seasonal Greenland glacier
velocity, Geophys. Res. Lett., 41, 7209–7216, https://doi.org/10.1002/2014GL061836,
2014.
Morlighem, M., Williams, C. N., Rignot, E., An, L., Arndt, J. E., Bamber, J.
L., Catania, G., Chauché, N., Dowdeswell, J. A., Dorschel, B., Fenty,
I., Hogan, K., Howat, I., Hubbard, A., Jakobsson, M., Jordan, T. M.,
Kjeldsen, K. K., Millan, R., Mayer, L., Mouginot, J., Noël, B. P. Y.,
O'Cofaigh, C., Palmer, S., Rysgaard, S., Seroussi, H., Siegert, M. J.,
Slabon, P., Straneo, F., van den Broeke, M. R., Weinrebe, W., Wood, M., and
Zinglersen, K. B.: BedMachine v3: Complete bed topography and ocean
bathymetry mapping of Greenland from multibeam echo sounding combined with
mass conservation, Geophys. Res. Lett., 44, 11051–11061,
https://doi.org/10.1002/2017GL074954, 2017.
Noël, B., van de Berg, W. J., van Wessem, J. M., van Meijgaard, E., van As, D., Lenaerts, J. T. M., Lhermitte, S., Kuipers Munneke, P., Smeets, C. J. P. P., van Ulft, L. H., van de Wal, R. S. W., and van den Broeke, M. R.: Modelling the climate and surface mass balance of polar ice sheets using RACMO2 – Part 1: Greenland (1958–2016), The Cryosphere, 12, 811–831, https://doi.org/10.5194/tc-12-811-2018, 2018.
Pitcher, L. H., Smith, L. C., Gleason, C. J., Miège, C., Ryan, J. C., Hagedorn, B., van As, D., Chu, W., and Forster, R. R.: Direct Observation of Winter Meltwater Drainage From the Greenland Ice Sheet, Geophys. Res. Lett., 47, 1–10, https://doi.org/10.1029/2019GL086521, 2020.
Ryser, C., Lüthi, M. P., Andrews, L. C., Catania, G. A., Funk, M.,
Hawley, R., Hoffman, M., and Neumann, T. A.: Caterpillar-like ice motion in
the ablation zone of the Greenland ice sheet, J. Geophys. Res.-Earth Surf.,
119, 2258–2271, https://doi.org/10.1002/2013JF003067, 2014a.
Ryser, C., Lüthi, M. P., Andrews, L. C., Hoffman, M. J., Catania, G. A.,
Hawley, R. L., Neumann, T. A., and Kristensen, S. S.: Sustained high basal
motion of the Greenland ice sheet revealed by borehole deformation, J.
Glaciol., 60, 647–660, https://doi.org/10.3189/2014JoG13J196, 2014b.
Schoof, C.: Ice-sheet acceleration driven by melt supply variability,
Nature, 468, 803–806, https://doi.org/10.1038/nature09618, 2010.
Shepherd, A., Hubbard, A., Nienow, P., King, M., McMillan, M., and Joughin,
I.: Greenland ice sheet motion coupled with daily melting in late summer,
Geophys. Res. Lett., 36, L01501, https://doi.org/10.1029/2008GL035758, 2009.
Sole, A., Nienow, P., Bartholomew, I., Mair, D., Cowton, T., Tedstone, A.,
and King, M. A.: Winter motion mediates dynamic response of the Greenland
Ice Sheet to warmer summers, Geophys. Res. Lett., 40, 3940–3944,
https://doi.org/10.1002/grl.50764, 2013.
Stevens, L. A., Behn, M. D., Das, S. B., Joughin, I., Noël, B. P. Y.,
van den Broeke, M. R., and Herring, T.: Greenland Ice Sheet flow response to
runoff variability, Geophys. Res. Lett., 43, 11295–11303,
https://doi.org/10.1002/2016GL070414, 2016.
van de Wal, R. S. W., Boot, W., van den Broeke, M. R., Smeets, C. J. P. P.,
Reijmer, C. H., Donker, J. J. A., and Oerlemans, J.: Large and rapid
melt-induced velocity changes in the ablation zone of the Greenland Ice
Sheet, Science, 321, 111–113, https://doi.org/10.1126/science.1158540,
2008.
van de Wal, R. S. W., Smeets, C. J. P. P., Boot, W., Stoffelen, M., van Kampen, R., Doyle, S. H., Wilhelms, F., van den Broeke, M. R., Reijmer, C. H., Oerlemans, J., and Hubbard, A.: Self-regulation of ice flow varies across the ablation area in south-west Greenland, The Cryosphere, 9, 603–611, https://doi.org/10.5194/tc-9-603-2015, 2015.
Walder, J. and Hallet, B.: Geometry of former subglacial water channels and cavities, J. Glaciol., 23, 335–346, 1979.
Werder, M. A., Hewitt, I. J., Schoof, C. G., and Flowers, G. E.: Modeling channelized and distributed subglacial drainage in two dimensions, J. Geophys. Res.-Earth Surf., 118, 2140–2158, https://doi.org/10.1002/jgrf.20146, 2013.
Wright, P., Harper, J., Humphrey, N., and Meierbachtol, T.: Measured basal
water pressure variability of the western Greenland Ice Sheet: Implications
for hydraulic potential, J. Geophys. Res.-Earth Surf., 121, 1134–1147,
https://doi.org/10.1002/2016JF003819, 2016.
Zoet, L. K. and Iverson, N. R.: Experimental determination of a
double-valued drag relationship for glacier sliding, J. Glaciol., 61,
1–7, https://doi.org/10.3189/2015JoG14J174, 2015.
Zwally, H. J., Abdalati, W., Herring, T., Larson, K., Saba, J., and Steffen,
K.: Surface Melt – Induced Acceleration of Greenland Ice-Sheet Flow,
Science, 297, 218–222, 2002.
Short summary
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.
We use surface and borehole measurements to investigate the generation and fate of basal...
