Université de Fribourg

The firn meltwater retention model intercomparison project (retmip) : evaluation of nine firn models at four weather station sites on the greenland ice sheet

Vandecrux, Baptiste ; Mottram, Ruth ; Langen, Peter L. ; Fausto, Robert S. ; Olesen, Martin ; Stevens, C. Max ; Verjans, Vincent ; Leeson, Amber ; Ligtenberg, Stefan ; Munneke, Peter Kuipers ; Marchenko, Sergey ; Pelt, Ward van ; Meyer, Colin R. ; Simonsen, Sebastian B. ; Heilig, Achim ; Samimi, Samira ; Marshall, Shawn ; Machguth, Horst ; MacFerrin, Michael ; Niwano, Masashi ; Miller, Olivia ; Voss, Clifford I. ; Box, Jason E.

In: The Cryosphere, 2020, vol. 14, no. 11, p. 3785-3810

Perennial snow, or firn, covers 80 % of the Greenland ice sheet and has the capacity to retain surface meltwater, influencing the ice sheet mass balance and contribution to sea-level rise. Multilayer firn models are traditionally used to simulate firn processes and estimate meltwater retention. We present, intercompare and evaluate outputs from nine firn models at four sites that represent...

Université de Fribourg

Worldwide version-controlled database of glacier thickness observations

Welty, Ethan ; Zemp, Michael ; Navarro, Francisco ; Huss, Matthias ; Fürst, Johannes J. ; Gärtner-Roer, Isabelle ; Landmann, Johannes ; Machguth, Horst ; Naegeli, Kathrin ; Andreassen, Liss M. ; Farinotti, Daniel ; Li, Huilin ; GlaThiDa Contributors

In: Earth System Science Data, 2020, vol. 12, no. 4, p. 3039–3055

Although worldwide inventories of glacier area have been coordinated internationally for several decades, a similar effort for glacier ice thicknesses was only initiated in 2013. Here, we present the third version of the Glacier Thickness Database (GlaThiDa v3), which includes 3 854 279 thickness measurements distributed over roughly 3000 glaciers worldwide. Overall, 14 % of global...

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...