Andreas Bauder

Last Name

Bauder

First Name

Andreas

ORCID

0000-0001-7197-7706

Organisational unit

09599 - Farinotti, Daniel / Farinotti, Daniel

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Publications1 - 10 of 79

Evolution of Rhonegletscher, Switzerland, over the past 125 years and in the future: application of an improved flowline model
Sugiyama, Shin; Bauder, Andreas; Zahno, Conradin; et al. (2007)
Annals of Glaciology ~ Papers from the International Symposium on Cryospheric Indicators of Global Climate Change: held in Cambridge, UK, on 21-25 August, 2006
To study the past and future evolution of Rhonegletscher, Switzerland, a flowline model was developed to include valley shape effects more accurately than conventional flowband models. In the model, the ice flux at a gridpoint was computed by a two-dimensional ice-flow model applied to the valley cross-section. The results suggested the underestimation of the accumulation area, which seems to be a general problem of flowline modelling arising from the model’s one-dimensional nature. The corrected mass balance was coupled with the equilibrium-line altitude (ELA) change, which was reconstructed for the period 1878–2003 from temperature and precipitation records, to run the model for the past 125 years. The model satisfactorily reproduced both changes in the terminus position and the total ice volume derived from digital elevation models of the surface obtained by analyses of old maps and aerial photographs. This showed the model’s potential to simulate glacier evolution when an accurate mass balance could be determined. The future evolution of Rhonegletscher was evaluated with three mass-balance conditions: the mean for the period 1994–2003, and the most negative (2003) and positive (1978) mass-balance values for the past 50 years. The model predicted volume changes of –18%, –58% and +38% after 50 years for the three conditions, respectively.
Host–virome associations in the weathering crust of a rapidly retreating temperate Alpine glacier
Varliero, Gilda; Bauder, Andreas; Stierli, Beat; et al. (2025)
Microbial Genomics
Glaciers are retreating rapidly, altering ecosystem dynamics and increasing meltwater outflow into populated areas. Understanding microbial-virome interactions is crucial for predicting the consequences of this release. We sampled ice from four shallow pits in the weathering crust of the Rhonegletscher, Swiss Alps, and found a microbiome dominated by bacteria and microeukaryotes, alongside a metavirome infecting both groups. Viruses exhibited variable host specificity, with some targeting particular taxa and others showing a broader infectivity range. Variable genomic regions, including metagenomic and metaviromic islands, were enriched in genes related to replication, recombination, repair and transposable elements. Detected auxiliary metabolic genes were primarily involved in host coenzyme biosynthesis, uptake or utilization and in altering bacterial methylation patterns to evade detection. These findings underscore the major role of viruses in regulating microbial dynamics in glaciers and their potential downstream environmental impacts.
Glacier-dammed lake outburst events of Gornersee, Switzerland
Huss, Matthias; Bauder, Andreas; Werder, Mauro; et al. (2007)
Journal of Glaciology
Gornersee, Switzerland, is an ice-marginal lake, which drains almost every year, subglacially, within a few days. We present an analysis of the lake outburst events between 1950 and 2005, as well as results of detailed field investigations related to the lake drainage in 2004 and 2005. The latter include measurements of lake geometry, water pressure in nearby boreholes and glacier surface motion. A distributed temperature-index melt model coupled to a linear-reservoir runoff model is used to calculate hourly discharge from the catchment of Gornergletscher in order to distinguish between the melt/precipitation component and the outburst component of the discharge hydrograph. In this way, drainage volume and timing are determined. From 1950 there is a clear trend for the outburst flood to occur earlier in the melt season, but there is no trend in lake discharge volumes. Peak discharges from the lake lie significantly below the values obtained using the empirical relation proposed by Clague and Mathews (1973). The shapes of the 2004 and 2005 lake outflow hydrographs differ substantially, suggesting different drainage mechanisms. From water balance considerations we infer a leakage of the glacier-dammed lake in 2005, starting 1 week prior to the lake outburst. During the drainage events, up to half of the lake water is temporarily stored in the glacial system, causing substantial uplift of the glacier surface.
The Swiss Glaciers 2005/06 and 2006/07
Bauder, Andreas; Funk, Martin; Huss, Matthias; et al. (2011)
The Swiss Glaciers. Glaciological Report
During the 127th and 128th year under review by the Cryospheric Commission, Swiss glaciers continued to lose both length and mass. The dominant weather conditions of this measurement period and the effects of global warming left clear traces. In autumn 2006, a length variation was determined for 92 of the 98 glaciers observed, while one year later such a result was obtained for 91 of 95 glaciers. In the two observation periods, 2005/2006 and 2006/2007, Swiss glaciers experienced further losses in length. Most of the measurement values lie between 0 and -30 m in both of these periods. Detailed mass balance figures were obtained for the three glaciers Bas`odino, Gries and Silvretta, and point measurements were taken at several additional glaciers. The glaciers suffered significant mass losses in both periods. The two periods rank third and forth negative in the long-term statistics only exceeded by the two extreme periods 2002/03 and 1997/98. In contrast to the period 2002/03 with the hot summer the negative balances in the two reported periods are mainly due to reduced precipitation in winter. Flow measurements were taken at selected glaciers in the Mauvoisin and Mattmark regions. The trend continued toward diminishing velocities, a clear reflection of the reduction in ice thickness due to lasting negative mass balances of the glaciers. The awareness of the role of the glaciers as a component in the water cycle has grown in the general public in recent years. High melt rates in summer are observed with increasing concern. Large attention received the impacts of continuous glacier retreat, as of Unterer Grindelwaldgletscher where a large rock mass collapsed due to the no longer existing back pressure by the thinned glacier tongue.
Proglacial erosion rates and processes in a glacierized catchment in the Swiss Alps
Delaney, Ian A.; Bauder, Andreas; Huss, Matthias; et al. (2018)
Earth Surface Processes and Landforms
In the Swiss Alps, climatic changes have not only caused glacier retreat, but also likely increased sedimentation downstream of glaciers. This material either originates from below the glacier or from periglacial environments, which are exposed as glaciers retreat, and often consist of easily erodible sediment. Griesgletscher's catchment in the Swiss Alps was examined to quantify erosion in the proglacial area, possible hydrological drivers and contributions of the sub‐ and periglacial sources. Digital elevation models, created from annual aerial photographs, were subtracted to determine annual volume changes in the proglacial area from 1986 to 2014. These data show a strong increase in proglacial erosion in the decade prior to 2012, coincident with increasing proglacial area size. However, examination of the gradient between discharge and sediment evacuation, and modeled sediment transport, could suggest that the proglacial area began to stabilize and sediment supply is limited. The large influx of sediment into the proglacial reservoir, which is roughly 2.5 times greater than the amount of sediment eroded from the proglacial area, demonstrates the importance of subglacial erosion to the catchment's sediment budget. Although far more sediment originates subglacially, erosion rates in the proglacial area are over 50 times greater than the rest of the catchment. In turn, both sub‐ and periglacial processes, in addition to constraining sediment supply, must be considered for assessing future sediment dynamics as glacier area shrinks and proglacial areas grow.
Cold ice in the ablation zone: Its relation to glacier hydrology and ice water content
Ryser, Claudia; Lüthi, Martin; Blindow, Norbert; et al. (2013)
Journal of Geophysical Research: Earth Surface
Cold ice within a polythermal ice body controls its flow dynamics through the temperature dependence of viscosity, and affects glacier hydrology by blocking water flow paths. Lakes on the surface, linked by persistent, deeply incised meltwater streams, are hallmark features of cold ice in the ablation zone of a glacier or ice sheet. Ice radar is a convenient method to map scattering from internal water bodies present in ice at the pressure melting temperature (PMT). Consequently, lack of internal scatters is indicative of cold ice. We use a helicopter-borne 30 MHz ice radar to delineate the extent of cold ice within Grenzgletscher (Zermatt, Swiss Alps). The inferred thermal structure is validated with temperature measurements in 15 deep boreholes, showing excellent agreement. The cold ice occupies 80–90 % of the total ice thickness in a 400 m wide flow band along the central flow line. Quantitative interpretation of ice radar scattering power indicates a decrease of ice water content between PMT and 0.5 K below PMT, as predicted by theory, and observed in the laboratory. The cold ice which emerges at the surface in the lower ablation zone is impermeable to water, and is thus devoid of moulins if not crevassed. The surface water from melt and rain is routed through deeply incised, persistent streams and lakes, and cryoconite holes are frequent, in stark contrast to the adjacent temperate ice from other tributaries. The cold ice thus has a strong control on glacier hydrology, but is likely to change due to continued warming.
Ultrasonic velocity experiments on ice cores to complement fabric measurements
Hellmann, Sebastian; Kerch, Johanna; Grab, Melchior; et al. (2021)
EGUsphere
The ice crystal structure and in particular the crystal orientation fabrics (COF) provide valuable information about the deformation history of ice sheets and glaciers. Therefore, COF analysis has been among the standard measurement techniques for most deep ice core drilling projects in the last three decades. The analysis depends on carefully prepared thin sections of ice that are measured with cross-polarised light microscopy or electron backscattering and diffraction (EBSD). The preparation of thin sections is labour-intensive and therefore only a discrete number of samples along the ice core is usually analysed. Geophysical methods such as ultrasonic sounding along the ice core could be employed to complement the discrete fabric data by providing data to fill the gaps. A suitable method needs to be reasonably fast, ideally non-invasive and provides unambiguous information in combination with the established methods. In our study, we demonstrate the feasibility of such ultrasonic experiments applied to an ice core to support the approved cross-polarised light microscopy method. Point-contact transducers transmitted ultrasonic waves into ice core samples from a temperate glacier. X-ray computer tomography measurements provide the required information to consider the effect of a two-phase medium (ice and air bubbles) in a porosity correction of the velocity. We determined the azimuthal variation of the seismic velocity. This variation is a result of seismic anisotropy due to the crystal orientation within the ice core volume. The measurements can be acquired within minutes and do not require an extensive preparation of ice samples. In addition, the COF of adjacent ice core samples was measured with cross-polarised light spectroscopy. From this, we derived the elasticity tensor and finally calculated the associated seismic velocities for the same azimuth and inclination angle as for the ultrasonic experiments. We compare these two velocity profiles and discover a significant discrepancy in presence of large ice grains. However, with an increasing number of ice grains both methods provide similar results. Although the ultrasonic measurements reveal some ambiguities, these can be resolved when considering the information derived from the standard analysis. We conclude that ultrasonic measurements along the ice core are suitable to support the established COF analysis for sufficiently small grains as found in polar cores. We recommend further exploration of the potential of the presented technique as it provides both the chance to obtain a continuous fabric profile and a direct link to large-scale seismic measurements in the vicinity of ice core drilling sites.
Ice-volume changes of selected glaciers in the Swiss Alps since the end of the 19th century
Bauder, Andreas; Funk, Martin; Huss, Matthias (2007)
Annals of Glaciology ~ Papers from the International Symposium on Cryospheric Indicators of Global Climate Change: Held in the City of Cambridge, England, 21-25 August, 2006
The evolution of surface topography of glaciers in the Swiss Alps is well documented with high-resolution aerial photographs repeatedly recorded since the 1960s and further back in time with topographic maps including elevation contour lines first surveyed in the mid-19th century. In order to quantify and interpret glacier changes in the Swiss Alps, time series of volume changes over the last 100–150 years have been collected. The available datasets provide a detailed spatial resolution for the retreat period since the end of the Little Ice Age. The spatial distribution as well as temporal variations of the thickness change were analyzed. A significant ice loss since the end of the 19th century was observed in the ablation area, while the changes in the accumulation area were small. We found moderate negative secular rates until the 1960s, followed by steady to positive rates for about two decades and strong ice loss starting in the 1980s which has lasted until the present. An evaluation of 19 glaciers revealed a total ice volume loss of about 13km3 since the 1870s, of which 8.7 km3 occurred since the 1920s and 3.5 km3 since 1980. Decadal mean net balance rates for the periods 1920–60, 1960–80 and 1980–present are –0.29, –0.03 and –0.53ma–1w.e., respectively.
Hazard assessment investigations due to recent changes in Triftgletscher, Bernese Alps, Switzerland
Dalban Canassy, Pierre; Bauder, Andreas; Dost, Michael; et al. (2011)
Natural Hazards and Earth System Sciences
The details and the consequences of the recent retreat of Triftgletscher (Gadmertal, Bernese Alps, Switzerland) have been investigated. Geodetic volume changes indicate a strong decrease since 1929 while the position of the terminus remained practically unchanged until 1990. The role played by calving in the tongue retreat running from 2000 to 2006 is confirmed by means of a mass balance model including a calving criterion. Results show that without calving, it would have taken two years longer for the lake to form than has been observed. The consequences of the ensuing tongue destabilization are surveyed, first with an ice avalanche model and second with a hydraulic study of the potential impulse wave triggered by the impact of the falling ice mass in the lake. Results point out that ice avalanches with volumes greater that 1 × 106 m3 will flow into the lake and that in the worst scenario, a discharge of 400 m3 s−1 is expected to reach the endangered area in Gadmertal 11 min after the break-off. In order to detect surface motion precursors to such ice avalanches, a photographic monitoring system was installed. The results indicate seasonal variations with peak velocity in summer and no significant change during the other months. Spectacular velocity increases were not observed so far.
Comment on ‘Integrated monitoring of mountain glaciers as key indicators of global climate change: the European Alps’ by Haeberli and others
Lüthi, Martin P.; Funk, Martin; Bauder, Andreas (2008)
Journal of Glaciology

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