Elmer/Ice News

Controls on calving at a Greenland tidewater glacier

Choosing the location Sermeq Kujalleq (Store Glacier), the calving behaviour of a typical Greenlandic tidewater glacier  was Difference in first principal deviatoric stress for undercut ‘retreated’ configurations compared with the non-undercut case, and fractures modelled in HiDEMinvestigated using the crevasse-depth (CD) calving law in Elmer/Ice and compared to results with the discrete element model HiDEM as well as observational data. This particular glacier has a stable front position due to a compressive arch between lateral pinning points,  which regularly lets ice that advances seawards across this arch calve back, whereas any undercut land inwards is countered by a readvance to the stable front position, which acts as an attractor between unstable super-critical and sub-critical regimes. It turns out that such a self-organising critical system can be very well described with a CD calving law in combination with a position (rather than a rate-based) calving algorithm in a continuum ice-flow model (Elmer/Ice) that resolves the major stress components at the ice front.

Read more:

Benn, D.I., J. Todd, A. Luckman, S. Bevan, T.R. Chudley, J. Åström, T. Zwinger, S. Cook, P. Christoffersen, 2023. Controls on calving at a large Greenland tidewater glacier: stress regime, self-organised criticality and the crevasse-depth calving lawJournal of Glaciology 1-17. doi:10.5194/10.1017/jog.2023.81


Elmer/Ice

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A closer look on ISMIP6-Antarctica results

In this latest article on ISMIP6-Antarctica intercomparison (including contribution from Elmer/Ice),  a closer look is taken on the results for high carbon emission tc 17 5197 2023 avatar webscenarios. The work focuses on key glaciers around the Antarctic Ice Sheet in order to quantify their projected dynamic mass loss through increased ice discharge into the ocean in response to changing oceanic conditions. Particular attention is given to glaciers contributing the most to sea level rise, as well as their vulnerability to changes in oceanic conditions.  These key glaciers - alongside the whole ice-sheet - in the further are investigated for the different sources of uncertainty and their relative role in projections. The findings are that in addition to the "usual suspects" in W-Antarctic ice-sheet (that be Thwaites and Pine Island) also outlet systems in E-Antarctica (Moscow University and Totten) show high sensitivity to increased oceanic ice-melt. Further, the uncertainties of the choice of climate models and the parametrization of the ocean melt have been investigated. Yet, overall, the highest uncertainty in dynamic ice-loss seems to be coming from the choice of the ice-sheet model. 

Read more:

Seroussi, H., Verjans, V., Nowicki, S., Payne, A. J., Goelzer, H., Lipscomb, W. H., Abe-Ouchi, A., Agosta, C., Albrecht, T., Asay-Davis, X., Barthel, A., Calov, R., Cullather, R., Dumas, C., Galton-Fenzi, B. K., Gladstone, R., Golledge, N. R., Gregory, J. M., Greve, R., Hattermann, T., Hoffman, M. J., Humbert, A., Huybrechts, P., Jourdain, N. C., Kleiner, T., Larour, E., Leguy, G. R., Lowry, D. P., Little, C. M., Morlighem, M., Pattyn, F., Pelle, T., Price, S. F., Quiquet, A., Reese, R., Schlegel, N.-J., Shepherd, A., Simon, E., Smith, R. S., Straneo, F., Sun, S., Trusel, L. D., Van Breedam, J., Van Katwyk, P., van de Wal, R. S. W., Winkelmann, R., Zhao, C., Zhang, T., and Zwinger, T., 2023. Insights into the vulnerability of Antarctic glaciers from the ISMIP6 ice sheet model ensemble and associated uncertaintyThe Cryosphere 17. doi:10.5194/tc-17-5197-2023

ISMIP6, Elmer/Ice

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GeoMIP scenarios applied to the Greenland ice sheet

Stratospheric Aerosol Injection (SAI) is a highly debated topic. The more it is important to look into the science (objectively,jgrf21835 fig 0006 m small without an agenda).  In order to contribute to this process, two ice dynamic models (SICOPOLIS and Elmer/Ice) driven by changes in surface mass balance (SMB) from four climate models to estimate the SLR contribution under the Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathway (RCP) 4.5, and 8.5, and Geoengineering Model Intercomparison Project G4 scenarios were deployed for the Greenland ice sheet. The G4 scenario adds 5 Tg/yr sulfate aerosols to the equatorial lower stratosphere (equivalent of 1/4 the 1991 Mt Pinatubo SO2 eruption) to the IPCC RCP4.5 scenario, which itself approximates the greenhouse gas emission commitments agreed in Paris in 2015. In the applied setups for the 2020–2090 period, the two ice sheet models show a reduction of mass loss between 31%–38% for the G4 compared to RCP4.5 scenario, which itself compared to RCP8.5 shows a lowering of 36%–48%. Both, the G4 and the 4.5 scenario indicate a lowering of the ice-flux across the grounding line into the ocean, as glaciers retreat from the coast and become land-terminated, with an exception of low-lying catchments (e.g., Jakobshavn, 79N, Zachariae Isstrøm, and Petermann glaciers)  that show an increased flux under RCP 4.5 compared to G4. Despite a dominating  variation of calving losses compared to differences in SMB between SICOPOLIS and Elmer/Ice, ice discharge losses are significant, ranging from 15% up to 42%, depending on the scenario. Picture (taken from the publication) to the right shows differences of the ensembles in flux and ice thickness between G4 and RCP4.5 runs.

Read more:

Moore, J. C., R. Greve, C. Yue, T.  Zwinger, F. Gillet-Chaulet, and L. Zhao, 2023. Reduced Ice Loss From Greenland Under Stratospheric Aerosol InjectionJournal of Geophysical Research: Earth Surface, 128. doi:10.1029/2023JF007112

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