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Over the last million years, cyclical changes in Earth's orbital parameters have been responsible for climate fluctuations and ice ages that have shaped our landscape. Current climate change, on the other hand, is caused by human greenhouse gas emissions and the CO2 content in the atmosphere exceeds the maximum value of the last 800,000 years by far. This is the main cause of current global climate change, which will affect human beings, and the whole ecosystem far into the future.While public awareness of climate change has increased massively over the last years, many misconceptions are still widespread. In order to increase awareness about the human impact versus natural processes, we are designing an interactive «Ice Age Machine», which will be placed at popular vantage points in Switzerland from September 2023 onwards. These interactive stations will allow groups of users to actively experience past ice ages as well as the corresponding environmental changes thanks to an innovative design and new visualization techniques based on artificial intelligence. The visitors will learn about the history of glaciations in the Alps, the extreme impact of human being on climate and what the future effects could be. The users have the opportunity to retrieve a photo showing them in action at the station in front of the panoramic ice age view to share via social media. To increase the visibility of the machine beyond the vantage points, communication activities on site and in the digital space (website, social media) will accompany the project., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

In this study we present a series of sensitivity experiments conducted for the Last Glacial Maximum (LGM, ~21000 years ago) over Europe using the regional climate Weather Research and Forecasting model (WRF). Using a 4 step 2-way nesting approach, we are able to reach a convection-permitting horizontal resolution over the inner part of the study area, covering Central Europe and the Alpine region. The main objective of the paper is to evaluate a model version including a series of new developments better suitable for the simulation of paleo-glacial time slices with respect to the ones employed in former studies. The evaluation of the model is conducted against newly available pollen-based reconstructions of the LGM European climate and takes into account the effect of two main sources of model uncertainty: a different height of continental glaciers at higher latitudes of the northern hemisphere and different land cover. Model results are in good agreement with evidence from the proxies, in particular for temperatures. Importantly, the consideration of different ensemble members for characterizing model uncertainty allows to increase the agreement of the model against the proxy reconstructions that would be obtained when considering a single model realization. The spread of the produced ensemble is relatively small for temperature, beside areas surrounding glaciers in summer. On the other hand, differences between the different ensemble members are very pronounced for precipitation, in particular in winter over areas highly affected by moisture advection from the Atlantic. This highlights the importance of the considered sources of uncertainty for the study of European LGM climate and allows to determine where the results of an RCM are more likely to be uncertain for the considered case study. Finally, the results are also used to demonstrate the added value of convection-permitting resolutions, at both local and regional scales, under glacial conditions.

In the 1950s and 1960s, specific radionuclides were released into the atmosphere as a result of nuclear weapons testing. This radioactive fallout left its signature on the accumulated layers of glaciers worldwide, thus providing a tracer for ice particles traveling within the gravitational ice flow and being released into the ablation zone. For surface ice dating purposes, we analyze here the activity of 239Pu, 240Pu and 236U radionuclides derived from more than 200 ice samples collected along five flowlines at the surface of Gauligletscher, Switzerland. It was found that contaminations appear band-wise along most of the sampled lines, revealing a V-shaped profile consistent with the ice flow field already observed. Similarities to activities found in ice cores permit the isochronal lines at the glacier from 1960 and 1963 to be identified. Hence this information is used to fine-tune an ice flow/mass balance model, and to accurately map the age of the entire glacier ice. Our results indicate the strong potential for combining radionuclide contamination and ice flow modeling in two different ways. First, such tracers provide unique information on the long-term ice motion of the entire glacier (and not only at its surface), and on the long-term mass balance, and therefore offer an extremely valuable data tool for calibrating ice flows within a model. Second, the dating of surface ice is highly relevant when conducting “horizontal ice core sampling”, i.e., when taking chronological samples of surface ice from the distant past, without having to perform expensive and logistically complex deep ice-core drilling. In conclusion, our results show that an airplane which crash-landed on the Gauligletscher in 1946 will likely soon be released from the ice close to the place where pieces have emerged in recent years, thus permitting the prognosis given in an earlier model to be revised considerably., The Cryosphere, 14 (11), ISSN:1994-0416, ISSN:1994-0424

Projections of future ice sheet mass loss and thus sea level rise rely on the parametrization of iceberg calving in ice sheet models. The interconnection between submarine melt-induced undercutting and calving is still poorly understood, which makes predicted contributions of tidewater glaciers to sea level rise uncertain. Here, we compare detailed 3-D simulations of fracture initiation obtained with the Helsinki Discrete Element Model (HiDEM) to observations, prior to a major calving event at Bowdoin Glacier, Northwest Greenland. Observations of a plume surfacing at the calving location suggest that local melt-undercutting influenced the size of the major calving event. Therefore, several experiments are conducted with various local and distributed (front-wide) undercut geometries. Although the number of undercut experiments is limited by computational requirements, one of the conjectured undercut geometries reproduces the crevasse leading to the observed major calving event in great detail. Our simulations show that undercutting leads to initiation of wider fractures more than 100 m upstream of the terminus, well-beyond the directly undercut region. When combining a moderate distributed undercut with local amplified undercuts at the two observed plumes, fracture initiation also increases in between the local undercuts. Thus, our results agree with previous studies suggesting the existence of a “calving amplifier” effect by submarine melt, both upglacier and across-glacier. Consequently, the simulations show the potentially large impact of submarine melt-induced undercutting on iceberg size., Frontiers in Earth Science, 8, ISSN:2296-6463

Measuring the ice flow motion accurately is essential to better understand the time evolution of glaciers and ice sheets and therefore to better anticipate the future consequence of climate change in terms of sea level rise. Although there are a variety of remote sensing methods to fill this task, in situ measurements are always needed for validation or to capture high-temporal-resolution movements. Yet glaciers are in general hostile environments where the installation of instruments might be tedious and risky when not impossible. Here we report the first-ever in situ measurements of ice flow motion using a remotely controlled unmanned aerial vehicle (UAV). We used a quadcopter UAV to land on a highly crevassed area of Eqip Sermia Glacier, West Greenland, to measure the displacement of the glacial surface with the aid of an onboard differential GNSS receiver. We measured approximately 70 cm of displacement over 4.36 h without setting foot onto the glacier – a result validated by applying UAV photogrammetry and template matching techniques. Our study demonstrates that UAVs are promising instruments for in situ monitoring and have great potential for capturing continuous ice flow variations in inaccessible glaciers – a task that remote sensing techniques can hardly achieve. ISSN:2193-0856 ISSN:2193-0864

Modelling paleo-glacier networks in mountain ranges on the millennial timescales requires ice flow approximations. Hybrid models calculating ice flow by combining vertical shearing (shallow ice approximation) and longitudinal stretching (shallow shelf approximation) have been applied to model paleo-glacier networks on steep terrain, yet their validity has not yet been assessed quantitatively. Moreover, hybrid models consistently yield higher ice thicknesses than Last Glacial Maximum geomorphological reconstructions in the European Alps. Here, we compare results based on the hybrid Parallel Ice Sheet Model (PISM) and the Stokes model Elmer/Ice on the Rhine Glacier, a catchment of the former European Alpine Icefield. For PISM, we also test two magnitudes of flux limitation in a scheme that reduces shearing velocities. We find that the flux limitation typically used in PISM yields significantly reduced shearing speeds and increases ice thicknesses by up to 500 m, partly explaining previous overestimations. However, reducing the ice flux limitation allows the hybrid model to minimize this mismatch and captures sliding speeds, ice thicknesses, ice extent and basal temperatures in close agreement with those obtained with the Stokes model., Journal of Glaciology, 65 (254), ISSN:0022-1430, ISSN:1727-5652