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Michelle Worek | Center for Energy and Environmental Sciences | Paul Scherrer Institute|
Oeschger Centre for Climate Change Research | University of Bern
New Ice Core from Tödi Summit Reveals Persistent Glaciation of the Alps since Early Holocene at an Altitude of around 3500 m
When we think about glaciation in the Alps, key periods come to mind such as the Last Glacial Maximum or the Little Ice Age. That is for good reason, as these are periods of maximum glacial extent which are well-recorded by moraines and can be dated, establishing a strong understanding of these high stands of glaciation. But what about periods of minimum glacial cover or ice-free conditions in the Alps? Understanding low stands of glaciation throughout the Holocene will help us to better constrain models predicting future Alpine deglaciation. Few available data from ice cores and prehistoric artefacts suggest a strong altitude gradient of Neoglaciation following the Holocene Climatic Optimum. More data from new ice cores will help us better understand the timing of Holocene glacial formation, particularly at high altitude.
Addressing this gap in knowledge is the motivation for my PhD project at the Paul Scherrer Institute and University of Bern. We’ve selected three previously unexplored sites in the Swiss Alps above 3000 m for ice core drilling. The first site, Tödi (3566 m asl), was successfully drilled to bedrock in 2023, and we found the ice still frozen to bed. Firn is no longer present on the summit, indicating the surface age is not modern due to a recent negative mass balance. Through analyses of 210Pb and 3H, we can narrow the surface age to pre-1960. 14C analyses of the deeper ice produce a continuous record extending to 10,000 years ago, indicating the mountain has been persistently glaciated since the Early Holocene. These results will help to refine our understanding of Alpine glaciation throughout the Holocene and emphasize the need to find more ancient, cold ice in the Alps while it is still preserved and unaffected by melting due to climate change.
Through the support of the CH-QUAT Society, I presented my research at the 2024 American Geoscience Union (AGU) Annual Meeting in Washington, D.C. This was a great opportunity to learn about the latest research across all fields of earth science, including the cryosphere and paleoclimatology. I reached the halfway point in my PhD, and as I consider the next stage in my career, this meeting enabled me to start networking with international colleagues and inquire about opportunities for future collaboration. Thank you, CH-QUAT, for helping make this experience at AGU possible!
Contact: Michelle Worek (Michelle Worek@psi.ch)
Robin von Allmen | Geoecology | Department of Environmental Sciences | University of Basel
Method Development and Application of Object Detection and Classification to Quaternary Fossil Pollen sequences from lake sediments and ice cores.
While many research areas such as food sciences and aerobiology experienced a rapid development in automated and assisted workflows for pollen analysis, fossil pollen samples in lake sediment and ice core archives have been neglected so far. Our initial work on the Late Quaternary sediment archive in Burgäschisee and Hütwilersee served as a “proof of principle” for our approach which we now want to replicate and use for other fossil archives such as the ice core from the Belukha Altai Mountain Range.
At AGU24 I presented the results of the initial study and the first preliminary results from the ice core samples by comparing manual and automated counts, respectively. The automated model accurately reproduces the same signals in vegetation change as observed in a manual downcore stratigraphy and does so consistently with similar detection and classification accuracy at all sites. Yet, improvements in imaging quality and the continuous development of faster and better image classification models promise to further elevate taxonomic resolution and detection accuracy in the near future.
I am very grateful for the incredible opportunity to travel to Washington DC and present the latest findings of my work at AGU24. Through presenting my work I was able to reach out to very resourceful companies and research groups that I wouldn’t have encountered otherwise. The network of project leaders and colleagues I’ve build at AGU24 will help me immensely during my Early Career to build bridges between different disciplines and hopefully to find funding partners for future projects.
Thank you, CH-QUAT!
Contact: Robin von Allmen (robinvonallmen@hotmail.com)
Julia Hasler | Geoecology | Department of Environmental Sciences | University of Basel
Global Estimates of Microfossil Concentrations in High-Alpine and Polar Ice Cores to inform Sampling Strategies
Thanks to the support from CH-QUAT, I had the opportunity to present my research at the American Geoscience Union (AGU) Winter Meeting in Washington D.C., USA.
Microfossils preserved in high-alpine and polar ice cores provide a unique window into past environmental conditions, offering insights into past regional vegetation, fire, and pollution patterns. Ice core drilling is costly, and the ice material is highly valuable. My study quantifies microfossils such as pollen and charcoal concentrations in ice cores from global high-altitude and polar regions, to optimize ice core sample quantities for future research. To identify the controlling factors of the microfossil concentrations we compared it with environmental parameters such as altitude, elevation above sea level, ice accumulation rates, and the predominant vegetation type in the surrounding area. Primary results indicate a strong correlation between pollen concentrations and vegetation type, with higher levels observed in boreal and temperate regions (e.g., European Alps, Altai) and lower concentrations in Arctic sites (e.g., Greenland), reflecting limited pollen productivity and greater distances from vegetation sources. Charcoal concentrations were elevated at sites proximal to regions of high fire activity, such as the southern boreal forests, Mediterranean ecosystems, and Andean locations above the Amazon basin.
Presenting this work at AGU enabled me to engage with a diverse community, whose feedback provided valuable perspectives for refining my approach and exploring interdisciplinary applications of my research. I am deeply grateful to CH-QUAT for supporting this opportunity and look forward to advancing this exciting field further!
Contact: Julia Hasler (julia.hasler@unibas.ch)
Balthasar L. Epprecht | Institute of Geological Sciences | University of Bern
Msc Thesis on the formation of down-stepping deltas (Lake Sämtisersee, Switzerland)
Lacustrine deltas that prograde at constant lake-levels form slightly inclined alluvial plains up to the river mouth. In Sämtis Valley, a glacially carved Alpine valley, five such alluvial plains, separated through steep delta front slopes occur on different elevations above today’s lake-level of Sämtisersee. Macroscopic analyses of the sedimentary record and detailed studies on the digital elevation model clearly indicate the terraces to originate from river deltas prograding at various lake-levels. The steep delta fronts and the relative orientation of the studied outcrops yield information about at least three episodic events during which the lake-level dropped by several meters without ever rising again to the old stage.
Glacial retreat since the LGM led to a stepwise reduction of Sämtisersee’s catchment area by dividing it into hydrologically isolated basins. These reductions in catchment area and the eventual full vanishing of the glaciers led to episodically reduced meltwater influx into Sämtisersee. The lithological terrace compositions and a sediment provenance analysis reveal strong evidence that the different terrace levels with the down-stepping terrace morphology in Sämtis Valley are predominantly inflow-controlled. In order to put a timestamp on the various terrace steps, optically stimulated luminescence (OSL) dating was applied. For further clarification of the ages, a piece of wood found in the sandy terrace sediments is currently being dated using radiocarbon dating.
I am grateful for the generous support provided by CH-QUAT, that enabled me to finance the whole field campaign. Being able to return to the field multiple times was immensely important in order to collect further samples for radiocarbon and OSL dating as well as to verify theoretical hypotheses concerning the glacial history of Sämtis Valley directly in the field.
Thank you very much, CH-QUAT!
Contact: Balthasar L. Epprecht (balthasar.epprecht@students.unibe.ch)
Leah Forsythe | Geology | ETH Zurich
CH-QUAT support of workshop attendance in Edinburgh.
Micromorphology is a discipline widely used in the study of glacigenic sediments. It applies basic principles of structural geology, sedimentology, and mapping on a microscale to provide insights into the processes, evolution, and deformation of sediments during glacial periods.
For my MSc thesis, I will utilize these techniques to deepen our understanding of the glacigenic sediments at Bürglen (Albis), where glacial diamicts are interbedded with Early Pleistocene sediments from the Höhere Deckenschotter Group (HDS). By relating micromorphological features to geological processes and macroscale observations, I aim to understand the context of sediment emplacement (e.g., subglacial traction till, subglacial debris flow, etc.) and the subsequent conditions of deformation. This research will contribute to our knowledge of the palaeo-landscape in the Northern Alpine Foreland.
Prior to choosing my thesis topic, micromorphology was a new concept for me. To gain foundational knowledge, I attended a five-day workshop in August 2024, hosted by Emrys Philips at the Lyell Centre (British Geological Survey) in Edinburgh, UK. During this workshop, I learned how to identify microstructures in diamicts, create meaningful morphological maps, and link these observations to geological processes. Under Emrys' supervision, I mapped two thin sections that will be included in my final thesis.
I am grateful for the generous support from CH-QUAT, which enabled me to learn from an expert in the field of glacial micromorphology. This experience has greatly benefited me on a personal level and will be crucial as I write my master's thesis.
Thank you, CH-QUAT!
Contact: Leah Forsythe (lforsythe@student.ethz.ch)
Gabriel Graf | Institute of Geological Science | University of Bern
Holocene lake-level changes controlled by climatic changes (Lake Sämtisersee, E Switzerland)
Lake Sämtis is located in the Alpstein (Appenzell Innerrhoden, E Switzerland). Drainage of the lake is controlled by a subaqueous karst outflow. Historically, the lake level is known to fluctuate seasonally from almost dry during hot summers to a high of ~15 m after heavy rainfall periods. This seasonal behaviour may also indicate a sensitivity to climatic changes on Holocene timescales. Such climatic control is suggested by exposed deltaic terraces indicating higher former lake levels (studied in detail by a second Master’s thesis by B. Epprecht). The aim of my Master's thesis is to reconstruct the palaeoclimatic history of Lake Sämtisersee using sediment cores taken from the lake bed. The core analysis focuses on lake level fluctuations including possible drying phases over the last ~6000 years. In addition, a correlation of the lake sediments with the sediments of the delta terraces will be attempted. By linking the two theses, we aim at a broad understanding of the hydroclimatic changes recorded in Lake Sämtissersee and the Late Quaternary history of the Alpstein area in general. The financial support from CH-Quat will allow me to carry out important fieldwork and radiocarbon dating of the cores. Excellent cores and dates will be a great basis for my Master's thesis. Thank you very much for your support for my research project!
Contact: Gabriel Graf (gabriel.graf@students.unibe.ch)
Simona Breu | Geoecology | Department of Environmental Sciences | University of Basel
Changes in fossil chironomid and cladoceran assemblages along water depth gradients
Thanks to the generous support from CH-QUAT, I had the opportunity to present my research on the use of fossil chironomid assemblages for reconstructing past water depths at the 22nd International Symposium on Chironomidae (ISC22) in Niš, Serbia.
Fossil remains of chironomids, whether in larvae or adult form, provide a unique perspective on the development of aquatic ecosystems over long periods. My study offers new insights into changes in fossil chironomid assemblages along the water depth gradient in Central European lakes. This dataset, detailing the composition of the chironomid assemblages along increasing water depth gradients, was used as a reference dataset to investigate water depth changes in a downcore study from Lake Lucerne (Switzerland). The results generally align with known geological records of water level fluctuations in Lake Lucerne. However, comparison with other proxies like for example pollen could be beneficial to support the current reconstruction.
Presenting my research findings at ISC22 allowed me to get a valuable exchanges of ideas and feedback from fellow researchers. Thank you, CH-QUAT, for making this possible.
Contact: Simona Breu (simona.breu@unibas.ch)
Francois Burgay | Oeschger Centre for Climate Change Research | University of Bern
Non-target screening analysis on ice and snow samples: a new opportunity to enhance our understanding on past and present atmospheric aerosol composition
Ice cores are unique environmental archives used to reconstruct past environmental and climate changes. So far, most studies have focused on the analysis of inorganic species, such as nitrate, sulfate, and trace elements. While their quantification has been extremely important for identifying past wildfires, volcanic eruptions, and the impact of human activities on the environment, these species only represent a small fraction of the submicron atmospheric aerosol mass. The large component is indeed composed of organic compounds. Despite constituting up to 70-90% of the submicron aerosol mass, organic compounds have been largely overlooked in ice-core studies, with few exceptions. This was primarily due to analytical limitations. Today, thanks to the development of high-resolution mass spectrometry and the implementation of non-target screening (NTS) workflows, it is possible to detect and identify an unprecedented number of compounds (several hundreds) from a single ice sample, unlocking the potential to improve our understanding of past environmental conditions.
With the support from CH-QUAT, I presented a poster at the European Geosciences Union General Assembly 2024 (EGU24), where I summarized the main findings obtained during my post-doc at the Laboratory of Environmental Chemistry of the Paul Scherrer Institute, under the supervision of Prof. Margit Schwikowski and Dr. Saša Bjelić. These include the development of a novel and highly sensitive NTS method for snow and ice-core analysis, and its application on two mid-latitude ice cores, namely Belukha (Siberia) and Colle Gnifetti (Europe), covering the period from 1750 to 2000 CE. A clear anthropogenic fingerprint has been identified during the industrial period with the occurrence of new, previously unknown chemical substances, mainly constituted by carbon, hydrogen, oxygen, nitrogen, and sulfur. Also, changes in the oxidation state of the organic compounds were observed, suggesting a possible increase in the oxidative capacity of the atmosphere. The conference represented a unique opportunity to connect with other ice-core and atmospheric scientists, and thanks to this event, exciting collaborations will start soon.
Contact: Francois Burgay (francois.burgay@gmail.com)