RESEARCH

Reconciling geological and modelled reconstructions of Alpine glacier evolution from the Last Glacial Maximum into the Holocene

Project (Co-PI) funded by the Swiss National Science Foundation (grant 200020-213077), ongoing (2023–2026).

Research summary

Quaternary glaciations have left numerous geological footprints in the landscape of the European Alps, especially during and after the Last Glacial Maximum (LGM). Despite extensive field evidence and dating constraints, the chronology of the glacier evolution is far from being well understood. Yet, understanding the relationship between climate change and glacial response since the LGM is important for setting current global warming and related glacier response into a long-term and dynamic context. Numerical models accounting for the glacier thermo-dynamics and mass balance have proven to be promising tools for simulating ice extent evolution under a variable climate. However, existing flow modelling reconstructions of the LGM Alpine Ice Field generally produce far too thick ice compared to observed trimlines, and the comparison of modelled extents to geological records such as moraines remains so far limited to maximum extents and largely ignores the transient record of deglaciation. These discrepancies between field- and model-based reconstructions is largely due to spatially too coarse models (≥ 1 km) that do not resolve the complex relief of the Alps.

Clearly, none of the existing and well-established traditional ice flow models can achieve the resolution required (200 m) in large scale and over timescales of several tens of millennia, either because they are computationally too expensive or because they are lacking essential physical processes. In contrast, the new Instructed Glacier Model (IGM) (Jouvet et al. 2022, J. Glac.) utilizes deep-learning to manufacture a cheap ice flow emulator trained from physical glacier models. This permits in turn to speed-up the overall model by several orders of magnitudes with minor loss in accuracy, and thereby to achieve very high-resolution. Building on this IGM approach we aim in this project to simulate the maximum state and deglaciation of the last glaciation in the European Alps in agreement with the geological record. This will be done by (i) further developing IGM to include ice thermo-mechanical effects and a module for sediment transport and moraine production, and by (ii) performing with this model a large number of transient simulations of palaeo glacier evolution in the Alps since the LGM and through the Holocene. These applications will aim to (i) resolve the issue of LGM ice thickness (ice sheet versus ice field) and (ii) produce dynamic simulations of deglaciation and Holocene glacier fluctuations (including minimum extent) by newly integrating geological records (such as trimlines, dated moraine sequences, erratic boulders, etc.). Ultimately this project will produce a well constrained high-resolution transient reconstruction of ice extent over the Alps and enhance our ability to interpret the palaeo record and our understanding of the spatio-temporal response of glaciers to climate variations from the LGM through the Holocene.

Keywords

Glacier, climate, geomorphology, ice flow modelling, deep learning, European Alps.

Long-term response of the mountain cryosphere to climate change – a comparative perspective of the Andes of central Chile and the European Alps

Project (Scientific Exchange) funded by the Swiss National Science Foundation (grant IZSEZ0_215412), completed (2023).

Research summary

Over the last two decades the importance of the Andean cryosphere, particularly as water resource, has been recognized in both the scientific literature and the public sphere. However, lack of field studies and limited knowledge regarding long-term cryosphere evolution has precluded basic knowledge for water-resource management and planning, particularly in the Andes of central Chile, a region that has been experiencing accelerated warming and a dramatic drought spell. There is an urgent need for more detailed mapping, geochronologic and geophysical data to help unravel the ice evolution in the Andes and the fate of this precious water reserve.

To contribute to this research gap, this project aims to build a network of scientists to support collaborative fieldwork research in the Andes of Chile and the European Alps. One of the main aims of the exchange is to discuss and train latest state-of-the-art field methods and techniques as widely used in the Glaciology and Geomorphodynamics Group of the Department of Geography at the University of Zurich. In addition, together with the Geochronology Group, we aim to assess the potential of applying 36Cl cosmogenic exposure-dating of moraines to unravel the cryosphere context previous to the 20th and 21st centuries climate change. Remote-sensing mapping of a glacial catchment in central Chile is jointly developed to interpret the past-to-present cryo-geomorphic record. In addition, geophysical methods are jointly trained, to be applied later in the field (first at test sites in the Swiss Alps, later in the Chilean Andes).

By applying common scientific efforts to assess future scenarios of the mountain cryosphere and associated water reserves for ecosystems and human use, this collaboration contributes to state-of-the-art knowledge critical for decision makers. The research benefits from the existing collaboration experience between the Chilean and Swiss partners and brings together expertise from Switzerland and Chile, two mountain countries that have an intrinsic interest in making known the value of their mountains.

Keywords

Deglaciation, glacial geomorphology, geochronology, palaeoglaciology, Andes, European Alps, Holocene, Late glacial.

Integration of historical glacier images into the Euro-Climhist database

Pilot project funded by the Sebastiana-Stiftung, ongoing (2022–2023).

Research summary

Glaciers are excellent climate indicators, and worldwide glacier retreat serves as a warning signal for current climate change, with its dramatic effects on humankind and environment. The visualization of glacier change by means of images is able to reach the most diverse sections of the population. Historical glacier images, especially from the so-called Little Ice Age (ca. 1300 to 1850 in the European Alps), show the earlier glacier fluctuations in a particularly impressive way and give us a unique insight into the climatic events of that time. These findings are in turn key to understanding present and possible future climate changes.

The present project aims to secure historical glacier images for the long term and make them accessible to a broad public. For this purpose, within the framework of a research collaboration between the Universities of Zurich and Bern, the Euro-Climhist database is conceptually extended to include glacier images. Subsequently, glacier images (Grindelwald, Mont Blanc area) and the corresponding metadata are be integrated into the Euro-Climhist database.

Read more: Integration von historischen Gletscherbildern in die Euro-Climhist-Datenbank

Keywords

Historical data, glacier images, glacier reconstructions, European Alps, Little Ice Age (LIA), perception.

Past and current deglaciation in the Central Andes of Chile – an integrative geomorphological and geochronological approach (DeglaciAndes)

Seed Money Grant 2018, funded by the Centro Latinoamericano-Suizo de la Universidad de San Gallen, Leading House Latin America, completed (2019–2020).

Research summary

The reconstruction and analysis of the past and current evolution of the cryosphere is crucial to assessing future changes and related consequences, especially those that have a high-impact, such as the change in freshwater resources. In this project, we aim at unraveling the processes of deglaciation in the semi-arid Central Andes of Chile (32°–38° S) to understand the long-term evolution of landscape during warming periods such as the current one. Dramatic changes in the local cryo-geomorphology have been observed during recent times, which we intend to put into long-term context of Holocene mountain environmental change. We target well-preserved glacial and paraglacial geomorphology, which can be used to identify a temporal sequence of geo-cryospheric evolution linked to climate.

To determine past glacier extents during Holocene maxima and the detailed reconstruction of subsequent glacier retreat, the project combines geomorphological mapping in the field and remote-sensing data with novel surface exposure dating techniques. Rock samples are gathered during joint fieldwork, pre-processed using the lab facilities available at both the Swiss and Chilean University, and eventually dated using 10Be and 36Cl cosmogenic nuclides. Finally, an integrated geo-cryospheric model of the evolution of the glacial environment at this part of the Andes is developed. The proposed methods allow a composite view on the evolution of landforms and Holocene glacier and climate history in the Central Andes of Chile, which will serve as a baseline for developing near future scenarios and for assessing the related impacts.

The project contributes to a better knowledge of the current water resources stored in ice bodies in the Central Andes of Chile, and of the past evolution of those ice bodies. Ice bodies such as glaciers and rock glaciers (permafrost indicators) in the high mountains provide a substantial part of the fresh-water resources, which is used for many economic activities in the lowlands. Despite the great importance of water as a critical resource especially in the dry summer months, little is known about the evolution of those ice bodies since the last deglaciation (i.e. Holocene, last ~12,000 years) in the Andes. This is striking given the projected climate change, because it is also unknown whether these natural resources can be used as a sustainable fresh-water source in the future.

The purpose of the partnership is to exchange geomorphological expertise during joint fieldwork. Moreover, knowledge transfer will strengthen the cosmogenic dating lab recently set up at the Chilean institution (incl. training of Chilean PhD student at Swiss lab). An expert workshop serves at discussing the results and further enhancing the research network of all partners through follow-up projects.

Keywords

Glaciers, deglaciation, geomorphology, water resources, surface exposure dating, Andes, Chile, Holocene.

Cryospheric changes in the central Andes of Chile (33° S) – an integrative remote sensing approach

Joint project between the Universities of Fribourg, Zurich, and Católica de Chile (Santiago), data from the German Aerospace Centre (DLR), ongoing.

Research summary

Loss of glacier ice is recognized as the largest contributor to the present sea-level rise, greatly affects available water resources for consumption and irrigation especially in dry areas, and may change local hazard situations. Glacier mass balance is a direct and an immediate response to atmospheric conditions, and has been recognized as an essential variable of climate system monitoring. Data of glacier mass balances are stored at, and made available through the World Glacier Monitoring Service (WGMS). However, these data are unevenly distributed around the globe, and very few information is available e.g. for the Andes. On the other hand, glacier information based on historical information (aerial photographs, maps) exist for certain Andean regions and can be compared with recent glacier behaviour and distribution, spanning a relatively long observation period to bear a full climatological signal. However, the sample of suitable glaciers is small and their regional representativeness needs to be assessed. Furthermore, the reliability of the individual time series can only be guaranteed if they are compared with a set of neighbouring glaciers.

TanDEM-X data are considered to be of unique value to assess glacier changes in the study region. In this project, we apply TanDEM-X data to calculate geodetic mass balances, and to investigate the representativeness of selected well-investigated glaciers (e.g., Loma Larga glacier in the Maipo valley of the central Andes of Chile) on a regional scale. In a second step, other glaciers such as Nieves Negras (Maipo valley) or Juncal Norte (Juncal valley) will be included in the analysis.

World Glacier Monitoring Service (WGMS)

Main funding through the Swiss GCOS Office at the Federal Office of Meteorology and Climatology MeteoSwiss and the Department of Geography, University of Zurich, ongoing.

Summary

The WGMS collects standardized observations on changes in mass, volume, area and length of glaciers with time (glacier fluctuations), as well as statistical information on the distribution of perennial surface ice in space (glacier inventories). Such glacier fluctuation and inventory data represent high-priority key indicators of climate change and are monitored as terrestrial variables within global climate-related observing systems directed by WMO, UNESCO, UNEP, IUGG/IACS and ICSU/WDS. They form a basis for hydrological modelling with respect to possible effects of atmospheric warming, and provide fundamental information in glaciology, glacial geomorphology and quaternary geology.

For more information: https://www.wgms.ch

Glacier variations in the western and central Alps: reconstruction of the LIA-glacier history by historical documents, connection to climate variability, art and perception

No dedicated funding, but still ongoing.

1. Mer de Glace – art & science

This interdisciplinary project tries to give an overview of the actual state of knowledge of the Mer de Glace, the largest glacier in France and the western Alps. Geomorphological and dendrogeomorphic studies allow the reconstruction of the palaeogeography (e.g. the last maximal glaciation). A great number of historical documents results in a concise history of the Mer de Glace during the Little Ice Age (LIA). The recent fluctuations of the glacier facing climate change are shown, ending in scenarios of the future (changing surface cover, reduced attractiveness of the landscape, growing natural hazards, big change of public perception of the glaciers).

More information: Click here

2. Die Grindelwaldgletscher – Kunst und Wissenschaft

This interdisciplinary project tries to reconstruct the history of the two Grindelwald glaciers in the Holocene using different methods (e.g. historical documents, dendrochronology, speleothems). The great number of visually rich historical documents (with a lot of newly discovered mid-19th century photographs) allows detailed results of the LIA frontal fluctuations. The impact of climate change on the future glacier extension until the end of the 21st century is estimated by model calculations. The huge ice loss in the last years resulted not only in a dramatic change of landscape, but also in a growing number of natural hazards. The change of the public perception of the famous two glaciers, especially in the last 200 years, is discussed.

More information: Click here

Promoting Sustainable Mountain Development for Global Change (SMD4GC)

Project funded by the Swiss Agency for Development and Cooperation (SDC/DEZA), completed (2014–2019).

Project summary

Mountain regions are key contexts for sustainable global development because (1) mountains provide critical and indispensable goods and services to a significant proportion of humankind; and (2) mountains are among the most disadvantaged regions in a global perspective: they are among the regions with the highest poverty rates, and among those most vulnerable to global (climate) change and related risks, which exacerbates already existing challenges and increases the pressure on mountain people and resources. With the SMD4GC programme, support to sustainable mountain development (SMD) is provided to increase the resilience of the mountain population, which is increasingly vulnerable due to the ongoing global changes.

The overall goal of SMD4GC is to essentially contribute to SMD under uncertain changes in climatic, environmental and socio-economic conditions, focusing on poverty and risk reduction. The objectives are to launch (policy instruments for SMD at different levels by local, national and international stakeholders and decision makers, and to implement knowledge-based SMD activities. These objectives will be pursued by generating the following key outputs:
        - Raised awareness on SMD issues
        - Increased promotion of and support to SMD activities
        - Enhanced capacities for SMD knowledge generation
        - Improved access to SMD knowledge and know-how
        - Increased stakeholder capacity
        - Application of knowledge and know-how in pilot studies

Read more: Why mountains matter for sustainable development

Cryospheric variations in the central Andes: an integrative geomorphological approach (CryoAndes)

Seed Money Grant for Latin America 2015, funded by the EPFL Leading House for the development and coordination of joint research cooperation programmes, completed (2015–2016).

Research summary

Water in the central Andes (32°–38° S), a semi-arid mountainous area, is of great importance and a critical resource especially in the dry summer months. Ice bodies, such as glaciers and rock glaciers (permafrost) in the high mountains, provide a substantial part of the fresh-water resources but also for intensive economical use for the lowlands including Santiago metropolitan region, Chile. However the evolution of these ice bodies since the last deglaciation (i.e., Holocene, last ~12,000 years), and in particular during historical times, and their feedback with climate is fairly unknown. In view of projected climate change, this is striking because it is also unknown whether these natural resources could be used as sustainable fresh-water source in the future. Understanding ice variability in the semi-arid Andes of Chile during past centuries (i.e., pre-instrumental time) can provide the urgent climate background context before the 20th/21st century global warming and from here to assess local atmosphere-cryosphere linkages. Nonetheless, this important palaeoclimate aspect has remained unappreciated until present.

The main objective of the proposed project is to develop and to apply an integrative geomorphologic approach to study cryospheric landforms such as glaciers, debris-covered glaciers and rock glaciers and their long-term evolution in the central Andes of Chile. We combine geomorphologic mapping using remote-sensing and field data with an innovative surface exposure dating technique to determine the ages of distinct moraine ridges. Surface exposure dating has been successfully applied in the northern and southern, but not in the central, Andes of Chile. This is a climatically very sensitive zone between the southern humid and northern arid Andes, embracing a key location for uncovering past migration of the southern westerlies, the main driver of local climate variability. The project will generate knowledge about a multifarious, patrimonial natural heritage and geological archive in the central Andes, which is nowadays not only threatened by climatic change but also economic activities (e.g., mining).

Keywords

Glaciers, moraines, water resources, geomorphology, mapping, surface exposure dating, central Andes, Chile, Holocene.

Glacier variations in southern South America: extension of the historical glacier record and connection to climate variability

Continental-scale glacier variations in Europe (Alps, Scandinavia) and their connection to climate: past – present – future

Project funded by the Swiss National Science Foundation (grant 200021-116354), completed (2007–2010).

Research summary

The understanding of long-term, natural climate variability on different spatial and temporal scales is crucial to assess the recent climate change in a global to regional context. Since glaciers are considered as very important climate indicators, the understanding of past and present glacier variations is a key task for evaluating current climate change. Alpine and Scandinavian glaciers react differently to variations of energy balance, temperature, precipitation and atmospheric circulation. The project investigates the importance of regional/continental temperature and precipitation as driving factors for glacier dynamics (retreats, advances) during the period from the Little Ice Age (LIA) to the early 21st century.

Historical information from different sources and archives allows the reconstruction of glacier length fluctuations and mass balances from (western) Scandinavian glaciers and of a transect from the western to the eastern Alps. Further, the sensitivity of Alpine and Scandinavian glaciers to variations in temperature and precipitation, including glacier advances and retreats covering half a millennium, are studied by means of (non-linear) statistical approaches. A complementary method by reconstruction of mass balances for the Alps and Scandinavia using a continuity approach is also applied. Finally, in combination with climate data based on multi-proxy reconstructions, this enables a synoptical analysis of European climate related to its significance for glacier fluctuations for the last half millennium.

We also address the question of a changing perception of the glaciers in the Alps and in Scandinavia for the last few centuries. The fear of threat by glaciers in early times has changed today to a fear of loss of glaciers as beautiful landscape by the current rapid change of climate.

The long-term glacier length record for the Alps and Scandinavia is stored in the existing database of the Global Terrestrial Network for Glaciers (GTN-G) as part of the World Glacier Monitoring Service (WGMS). A close cooperation between the Universities in Bern/Zurich and Bergen, Norway (Bjerknes Centre for Climate Research), ensures a mutual enrichment of the scientific research by data and knowledge exchange. Finally, to inform the public about the consequences of the current glacier change is crucial, and glaciers are excellent indicators for the public perception of climate change in mountainous areas.

Keywords

Glacier reconstructions, historical data, glacier mass balance, glacier variations, glacier simulations, Alps, Scandinavia, Little Ice Age (LIA), synoptic climatology, perception.

Department of Geography | University of Zurich | © Samuel Nussbaumer, 2024