3rd CLIMACT Seminar Series - Episode #8

Special seminar with 4 recipients of the 2021 CLIMACT Starting Grants!

Zoom link: epfl.zoom.us/j/63821341998

Investigation of permafrost instability based on a thermo-mechanical numerical model

The rise in global mean temperatures induced by climate change causes accelerated permafrost degradation. In high mountain rock slopes, rock falls in permafrost areas are triggered by decreasing restraining forces such as friction loss in joints or fatigue of rock bridges. Although our knowledge of the thermal influence on permafrost degradation has improved over the last decades, its mechanical effect on rock slope destabilization remains rather poorly understood.

In this presentation, Johan Gaume and his team modeled the Mont fort geological structure (Verbier, CH) using the 3D Distinct Elements Numerical Method (3DEC software) to simulate and analyze rock failure processes. Their developed thermo-mechanical joint model simulates the main permafrost rock destabilization processes, i.e. joint strength temperature dependency. The results show that temperature changes affect the rock stability deeper than the active layer.

The study advances the understanding of thermo-mechanical failure processes in permafrost rock slopes, with several potential applications in structural engineering and natural hazards.

Presented by Grégoire Bobillier, Post-doctoral researcher in the Alpine Mass Movements research group I WSL-SLF
 

Enhanced weathering for carbon sequestration: A case study for Swiss agricultural soils

In the context of current climate change trajectory, carbon dioxide removal technologies are receiving increasing interest. Among existing approaches, enhanced weathering (EW) represents a promising methodology relying on soil amendment with powdered silicate rocks to accelerate natural chemical weathering and associated atmospheric CO₂ uptake. However, EW is still in early stages of evaluation with efficiency estimates often based on simplified representations of soil biogeochemical and hydrological transport processes, either from small-scale experiments or global-scale models.

Here, the project team developed a synthetic model linking expected CO₂ capture with natural and technology-related CO₂ emissions to assess the relevance of EW in Swiss croplands. Combining available techno-economic and specific carbon sequestration data with usually unaccounted geochemical processes, they show that the timescales to achieve net CO₂ sequestration are highly variable and generally not satisfying current mitigation targets. These results provide a critical assessment of EW implementation and identify major blind spots underlying its effectiveness.

Presented by Nicolas Escoffier, First assistant at the LAKES research group of the Faculty of Geosciences and Environment I UNIL
 

Did you say starting (grant)? Towards a data base and methodology to study Swiss urban soils environmental functions

In this presentation, Antoine Vialle will briefly summarize the goal and developed approached of my Climact-granted research project on carbon sequestration in urban soils within urban requalification projects. In particular, he will highlight how he took advantage of the so called “starting” grant as a seed money at an early stage of his researcher career by commenting the significant deviations from his initial proposal in terms of main scientific and societal outputs, but also critical challenges.

Presented by Antoine Vialle, Project leader at the Competence Centre in Sustainability (CCD) I UNIL

Stone pine colonisation in the Alps: ups and downs through a valley and the project

The project team combines modern aircraft-based sensors with deep-learning data analysis and in-situ observations to generate spatially explicit inventories of species in the treeline ecotone within one Alpine valley. When validated, the approach is intended to be extended over broad regions where in-situ measurements are not feasible and satellite imagery does not provide a sufficient level of detail. This information should enhance the forecasting capacity of species distribution models designed to predict the evolution of vegetation as a result of climate warming.

Jan Skaloud presents the methodology to achieve this goal after the envisaged approach had to be redesigned during the project, as the data collected by the world’s finest imaging spectrometer for the study did not meet the localization accuracy required. This highlights the importance of having the ability to implement and control all stages of the processing chain in-house and to present data openly in their raw form.

Presented by Jan Skaloud, Senior Scientist at the Geodetic Engineering Laboratory of the School of Architecture, Civil and Environmental Engineering (ENAC) I EPFL