Université de Fribourg

Potential future lakes from continued glacier shrinkage in the Aosta Valley Region (Western Alps, Italy)

Viani, Cristina ; Machguth, Horst ; Huggel, Christian ; Godio, Alberto ; Franco, Diego ; Perotti, Luigi ; Giardino, Marco

In: Geomorphology, 2020, vol. 355, p. 107068

Aosta Valley (Western Alps, Italy) is the region with the largest glacierized area of Italy. Like other high mountain regions, it has shown a significant glacier retreat starting from the end of the ‘Little Ice Age’ that is expected to continue in the future. As a direct consequence of glacier shrinkage, glacier-bed overdeepenings become exposed, offering suitable geomorphological ...

Université de Fribourg

Rapid expansion of Greenland’s low-permeability ice slabs

MacFerrin, Mike ; Machguth, Horst ; As, Dirk van ; Charalampidis, C. ; Stevens, C. M. ; Heilig, A. ; Vandecrux, B. ; Langen, P. L. ; Mottram, R. ; Fettweis, Xavier ; Broeke, Michiel R. van den ; Pfeffer, W. T. ; Moussavi, M. S. ; Abdalati, W.

In: Nature, 2019, vol. 573, no. 7774, p. 403–407

In recent decades, meltwater runoff has accelerated to become the dominant mechanism for mass loss in the Greenland ice sheet1,2,3. In Greenland’s high- elevation interior, porous snow and firn accumulate; these can absorb surface meltwater and inhibit runoff4, but this buffering effect is limited if enough water refreezes near the surface to restrict percolation5,6. However, the influence...

Université de Fribourg

Ice-penetrating radar survey of the subsurface debris field at Camp Century, Greenland

Karlsson, Nanna B. ; Colgan, William T. ; Binder, Daniel ; Machguth, Horst ; Abermann, Jakob ; Hansen, Karina ; Pedersen, Allan Ø.

In: Cold Regions Science and Technology, 2019, vol. 165, p. 102788

The warming climate is changing the surface dynamics of the Greenland Ice Sheet, including the balance between snowfall and melt. Increasing surface melt impacts the structure of the relatively porous near-surface layer known as firn. Camp Century, a base abandoned in 1967, now comprises a subsurface debris field within the firn in Northwest Greenland. We collected 80 km of 100 or 250 MHz...

Université de Fribourg

Strong contrast in mass and energy balance between a coastal mountain glacier and the Greenland ice sheet

Abermann, Jakob ; As, Dirk Van ; Wacker, Stefan ; Langley, Kirsty ; Machguth, Horst ; Fausto, Robert Schjøtt

In: Journal of Glaciology, 2019, vol. 65, no. 250, p. 263–269

We show a strong difference in surface mass and energy balance of a mountain glacier and two sites on the ice sheet at 64°N in West Greenland using stake and automated weather station observations. Net surface mass balance is on average 2.2 m w.e. less negative at the coast compared with the ice sheet in the same elevation. We find a larger energy turnover at the ice sheet margin on...

Université de Fribourg

A consensus estimate for the ice thickness distribution of all glaciers on Earth

Farinotti, Daniel ; Huss, Matthias ; Fürst, Johannes J. ; Landmann, Johannes ; Machguth, Horst ; Maussion, Fabien ; Pandit, Ankur

In: Nature Geoscience, 2019, vol. 12, no. 3, p. 168–173

Knowledge of the ice thickness distribution of the world’s glaciers is a fundamental prerequisite for a range of studies. Projections of future glacier change, estimates of the available freshwater resources or assessments of potential sea-level rise all need glacier ice thickness to be accurately constrained. Previous estimates of global glacier volumes are mostly based on scaling...

Université de Fribourg

Firn data compilation reveals widespread decrease of firn air content in western Greenland

Vandecrux, Baptiste ; MacFerrin, Michael ; Machguth, Horst ; Colgan, William T. ; As, Dirk van ; Heilig, Achim ; Stevens, C. Max ; Charalampidis, Charalampos ; Fausto, Robert S. ; Morris, Elizabeth M. ; Mosley-Thompson, Ellen ; Koenig, Lora ; Montgomery, Lynn N. ; Miège, Clément ; Simonsen, Sebastian B. ; Ingeman-Nielsen, Thomas ; Box, Jason E.

In: The Cryosphere, 2019, vol. 13, no. 3, p. 845–859

The perennial snow, or firn, on the Greenland ice sheet each summer stores part of the meltwater formed at the surface, buffering the ice sheet’s contribution to sea level. We gathered observations of firn air content, indicative of the space available in the firn to retain meltwater, and find that this air content remained stable in cold regions of the firn over the last 65 years but...

Université de Fribourg

A large impact crater beneath Hiawatha Glacier in northwest Greenland

Kjær, Kurt H. ; Larsen, Nicolaj K. ; Binder, Tobias ; Bjørk, Anders A. ; Eisen, Olaf ; Fahnestock, Mark A. ; Funder, Svend ; Garde, Adam A. ; Haack, Henning ; Helm, Veit ; Houmark-Nielsen, Michael ; Kjeldsen, Kristian K. ; Khan, Shfaqat A. ; Machguth, Horst ; McDonald, Iain ; Morlighem, Mathieu ; Mouginot, Jérémie ; Paden, John D. ; Waight, Tod E. ; Weikusat, Christian ; Willerslev, Eske ; MacGregor, Joseph A.

In: Science Advances, 2018, vol. 4, no. 11, p. eaar8173

We report the discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground...

Université de Fribourg

A snow density dataset for improving surface boundary conditions in greenland ice sheet firn modeling

Fausto, Robert S. ; Box, Jason E. ; Vandecrux, Baptiste ; As, Dirk van ; Steffen, Konrad ; MacFerrin, Michael J. ; Machguth, Horst ; Colgan, William ; Koenig, Lora S. ; McGrath, Daniel ; Charalampidis, Charalampos ; Braithwaite, Roger J.

In: Frontiers in Earth Science, 2018, vol. 6, p. -

The surface snow density of glaciers and ice sheets is of fundamental importance in converting volume to mass in both altimetry and surface mass balance studies, yet it is often poorly constrained. Site-specific surface snow densities are typically derived from empirical relations based on temperature and wind speed. These parameterizations commonly calculate the average density of the top...

Université de Fribourg

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

Cohen, Denis ; Gillet-Chaulet, Fabien ; Haeberli, Wilfried ; Machguth, Horst ; Fischer, Urs H.

In: The Cryosphere, 2018, vol. 12, no. 8, p. 2515–2544

At the Last Glacial Maximum (LGM), the Rhine glacier in the Swiss Alps covered an area of about 16000km2. As part of an integrative study about the safety of repositories for radioactive waste under ice age conditions in Switzerland, we modeled the Rhine glacier using a thermodynamically coupled three-dimensional, transient Stokes flow and heat transport model down to a horizontal resolution...