Effect of ice thickness distribution on glacier evolution

Stage de M2 ou de fin d’étude de 4 à 6 mois, début de stage souhaité en juin 2021

The effects of climate change on water resources and sea-level are largely determined by the size of the ice reservoirs around the world. Specifically, the spatial distribution of the ice masses influence the timing of their responses to climate changes, and in turn of their contributions to sea-level [SROCC et al., 2019]. Despite mountain glaciers represent only around 1% of the today global ice volume (the rest comes from the large Greenland and Antarctic ice sheets), they had represented between 20 and 30% of contribution to sea-level rise during the last decades, and are expected to contribute to the same proportion during the remaining 21st century. However, mountain glacier ice thickness estimates are still largely uncertain at global scale, and current models are affected by strong artifacts due to the use of simplified modeling approaches [Rabatel et al., 2018]. While the surface flow velocity of glaciers is closely linked to the spatial distribution of the ice thicknesses, this parameter has not yet been used in models due to a lack of observations. At IGE, we have developed an automatic processing chain to derive glacier surface flow velocity at regional scale using satellite observations from multiple sensor (optical, radar). This workflow was used to provide the first comprehensive view of the flow of the world’s glacier at a resolution of 50 m. This new database of glacier surface flow velocity has been used to construct an updated global ice volume based on the well-known Shallow Ice Approximation approach, providing the first global thickness estimates based on the inversion of surface velocities. The results highlight important disparities with existing state of the art estimates, and specifically in the Arctic where most of the ice volume is located. These large differences are likely to influence the timing of glacier retreat, the dynamical response of glacier to climate change but also the spatial interactions in
between adjacent drainage basins for ice caps and ice fields.

The goal of this internship is to conduct simulation of glacier evolution in the coming century using the open source Open Global Glacier Model [OGGM, Maussion et al., 2019]. Simulations will be launched for a set of glaciers located in the Russian and Canadian Arctic, the Patagonian Icefields and the Himalayas, as well as regionally. The candidate will use different initial ice thickness estimates derived from the inversion of ice velocity and from the state-of-the-art literature [Millan et al., submitted, 2021 ; Farinotti et al., 2019]. The candidate will compare the dynamical responses and glacier ice melt evolution using various glacier initial states under the standard RCP or SSP scenarios used in the IPCC reports where climatological data are extracted from CMIP5/6 experiments. Additionally, the candidate will document the evolution of glacier drainage basin evolution and specifically the dynamical interactions of neighboring glaciers. We are looking for a Master student in Earth Sciences, with a good knowledge of python programming and of the physics of glaciers. The internship is for a duration between 4/5 and 6 months and will be held at the IGE laboratory in Grenoble, supervised by Nicolas Champollion (nicolas.champollion univ-grenoble-alpes.fr) and Romain Millan (romain.millan univ-grenoble-alpes.fr).