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Elastic deformation plays a non-negligible role in Greenland’s outlet glacier flow (2021)

Christmann, Julia ; Helm, Veit ; Khan, Shfaqat Abbas ; [et al.]

Nature Publishing Group UK

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Publication Date: 2023-11-13

Description: Future projections of global mean sea level change are uncertain, partly because of our limited understanding of the dynamics of Greenland’s outlet glaciers. Here we study Nioghalvfjerdsbræ, an outlet glacier of the Northeast Greenland Ice Stream that holds 1.1 m sea-level equivalent of ice. We use GPS observations and numerical modelling to investigate the role of tides as well as the elastic contribution to glacier flow. We find that ocean tides alter the basal lubrication of the glacier up to 10 km inland of the grounding line, and that their influence is best described by a viscoelastic rather than a viscous model. Further inland, sliding is the dominant mechanism of fast glacier motion, and the ice flow induces persistent elastic strain. We conclude that elastic deformation plays a role in glacier flow, particularly in areas of steep topographic changes and fast ice velocities.

Description: Ice flow dynamics in Greenland’s outlet glaciers are influenced by elastic deformation, both in the area of tidal influence up to 14 km inland from the grounding line and further upstream, suggest analyses of GPS observations and numerical simulations.

Description: Bundesministerium für Bildung und Forschung (Federal Ministry of Education and Research) https://doi.org/10.13039/501100002347

Description: European Union’s Horizon 2020 Research and Innovation Programme

Description: https://doi.org/10.1594/PANGAEA.928940

Description: https://nsidc.org/data/IDBMG4

Description: https://gitlab.awi.de/jchristm/viscoelastic-79ng-greenland

Description: https://doi.org/10.5281/zenodo.5507115

Description: https://doi.org/10.5281/zenodo.5506953

Keywords: ddc:551.31 ; Climate change ; Cryospheric science ; Hydrology

Language: English

Type: doc-type:article

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Return to rapid ice loss in Greenland and record loss in 2019 detected by the GRACE-FO satellites (2020)

Sasgen, Ingo ; Wouters, Bert ; Gardner, Alex S. ; [et al.]

Nature Publishing Group UK

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Publication Date: 2023-11-16

Description: Between 2003-2016, the Greenland ice sheet (GrIS) was one of the largest contributors to sea level rise, as it lost about 255 Gt of ice per year. This mass loss slowed in 2017 and 2018 to about 100 Gt yr〈sup〉−1〈/sup〉. Here we examine further changes in rate of GrIS mass loss, by analyzing data from the GRACE-FO (Gravity Recovery and Climate Experiment – Follow On) satellite mission, launched in May 2018. Using simulations with regional climate models we show that the mass losses observed in 2017 and 2018 by the GRACE and GRACE-FO missions are lower than in any other two year period between 2003 and 2019, the combined period of the two missions. We find that this reduced ice loss results from two anomalous cold summers in western Greenland, compounded by snow-rich autumn and winter conditions in the east. For 2019, GRACE-FO reveals a return to high melt rates leading to a mass loss of 223 ± 12 Gt month〈sup〉−1〈/sup〉 during the month of July alone, and a record annual mass loss of 532 ± 58 Gt yr〈sup〉−1〈/sup〉.

Description: Mass loss from the Greenland ice sheet returned to record levels in 2019, following unusually small loss in 2017-18, according to an analysis of satellite data from GRACE and its follow-on mission GRACE-FO.

Description: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Alfred-Wegener- Institute, Helmholtz Centre for Polar and Marine Research) https://doi.org/10.13039/501100003207

Description: Helmholtz Association https://doi.org/10.13039/501100009318

Description: http://geoweb.princeton.edu/people/simons/software.html

Keywords: ddc:551 ; Climate change ; Cryospheric science ; Greenland ; ice loss

Language: English

Type: doc-type:article

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Exploration of an ice-cliff grounding zone in Antarctica reveals frozen-on meltwater and high productivity (2021)

Owsianowski, Nils ; Richter, Claudio ; Owsianowski, Nils; Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany ; [et al.]

Nature Publishing Group UK

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Publication Date: 2024-01-19

Description: Ice fluxes across the grounding zone affect global ice-sheet mass loss and sea level rise. Although recent changes in ice fluxes are well constrained by remote sensing, future projections remain uncertain, because key environments affecting ice-sheet dynamics – the ice-sheet bed and grounding zone – are largely unknown. Here, we used a remotely operated vehicle to explore the grounding zone of a Weddell Sea tidewater ice cliff. At 148 m we found a 0.3–0.5 m gap between the ice and the seafloor and a 0.4 m clear facies of debris- and bubble-free basal ice, suggesting freeze-on of meltwater in the distal marine portion of the ice sheet over the last 400 yr. Ploughmarks and low epifauna cover reveal recent grounding line retreat, as corroborated by satellite remote sensing. We found dense algal tufts on the ice cliff and high phytoplankton pigment concentrations, suggesting high productivity fuelled by nutrients from ice melt. As grounded tidewater ice cliffs rim 38% of the Antarctic continent, sinking and downwelling of organic matter along with low benthic turnover may contribute to enhanced carbon sequestration, providing a potentially important feedback to climate.

Description: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Alfred-Wegener- Institute, Helmholtz Centre for Polar and Marine Research) https://doi.org/10.13039/501100003207

Description: https://doi.org/10.1594/PANGAEA.909526

Description: https://doi.org/10.1594/PANGAEA.924822

Keywords: ddc:577.7 ; Cryospheric science ; Environmental impact ; Marine biology ; Physical oceanography

Language: English

Type: doc-type:article

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