Two new papers in TC
Two new paper using Elmer/Ice just published in The Cryosphere !
In Gudmundsson et al. (2012), the stability of grounding line on reverse slope is questioned for three-dimensonal geometries. As an important result, it is found that grounding line is not unconditionally unstable on reverse slope when considering the two horizontal dimensions. Retrograde bed slopes at the grounding lines of marine ice sheets, such as the West Antarctic Ice Sheet (WAIS), do not per se imply an instability, nor do they imply that these regions are close to a threshold of instability. This result clearly questions those estimates of the potential near-future contribution of WAIS to global sea level change based solely on the notion that WAIS, resting on a retrograde slope, must be inherently unstable.
In Gillet-Chaulet et al. (2012), we investigate with Elmer/Ice how current ice loss of the Greenland Ice Sheet may endure over the next century. This relies on three essential developments: the complete solution of the full system of equations governing ice deformation; an unstructured mesh to usefully resolve outlet glaciers and the use of inverse methods to better constrain poorly known parameters using observations. We show that the modelled ice discharge is in good agreement with observations on the continental scale and for individual outlets. By conducting perturbation experiments, we find that increasing ablation tends to reduce outflow and on its own has a stabilising effect, if destabilisation processes maintain themselves over time, current increases in the rate of ice loss are likely to continue. This work was performed using HPC resources from GENCI-CINES and from the Grenoble University High Performance Computing centre. This work is a contribution to the ice2sea project.