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Imaggeo on Mondays: Tongue of a small giant

Imaggeo on Mondays: Tongue of a small giant

In a world where climate change causes many mountain glaciers to shrink away, bucking the ‘melting’ trend is not easy. In today’s post, Antonello Provenzale, a researcher in Italy, tells us of one glacier in the Alps which is doing just that.

Mountain glaciers are retreating worldwide, with the possible exception of the Karakoram area. For most glaciers, ablation (ice melt) during the warm season is stronger than the accumulation of new ice by snowfall. As a result, while glacier ice flows downhill, the accelerated melting at lower elevation forces the terminus of the glacier to retreat uphill, with a net loss of ice volume.

Such behavior is especially evident on the southern flank of the Alps, where many mountain glaciers have dramatically reduced their dimensions, often fragmenting into smaller, detached pieces.

An important exception is represented by the Miage glacier in Val Veny, Val d’Aosta, northwestern Italy, at the base of the Mount Blanc massif. This glacier is covered with a thick layer of debris, which protects the underlying ice from the direct heating by sunlight. The rocks which make up the debris are poor heat conductors and thus preserve the ice beneath them, making this glacier particularly stable.

This glacier is so stationary that vegetation and trees have grown on its margins and on the debris. Several ponds punctuate the surface of the glacier, as well as some areas on its sides. The Miage lake, for example, is directly in contact with the slowly flowing ice and it is sometimes run by large outburst waves generated by huge blocks of ice and rock falling into the lake water.

This picture was taken in September 2014, during a field excursion of the Italian Glaciological Committee. The image is a composition (stitch) of several images taken with a moderate wide angle lens on a rangefinder digital camera.

By Antonello Provenzale studies Geophysical Fluid Dynamics, Earth System processes and Geosphere-Biosphere interactions at the Institute of Geosciences and Earth Resources of the National Research Council of Italy.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Sneaking up from above

Imaggeo on Mondays: Sneaking up from above

Take some ice, mix in some rock, snow and maybe a little mud and the result is a rock glacier. Unlike ice glaciers (the ones we are most familiar with), rock glaciers have very little ice at the surface. Looking at today’s featured image, you’d be forgiven for thinking the Morenas Coloradas rock glacier wasn’t a glacier at all. But appearances can be misleading; as Jan Blöthe (a researcher at the University of Bonn) explains in today’s post.

The picture shows the Morenas Coloradas rock glacier, a pivotal example of actively creeping permafrost (ground that remains frozen for periods longer than two consecutive years) in the dry central Andes of Argentina. The rock glacier is located in the “Cordon del Plata” range, some 50 km east of the city of Mendoza.

The rock glacier fills the entire valley and slowly creeps downslope creating impressive lobes and tongues with steep fronts. With more than 4 km length, the Morenas Coloradas is one of the largest rock glaciers of the central Andes.

Taken from a drone, the picture looks straight up the rock glacier into the main amphitheatre-like valley formed by glacial erosion located at ~4500 m.a.s.l. From there, large amounts of loose debris are moved down the valley at speeds on the order of a few meters per year. The creeping process forms tongues of material that override each other, producing the characteristic surface with steps, ridges and furrows.

The central Andes of Argentina are semi-arid, receiving less than 500 mm of precipitation per year, mainly falling as snow during the winter. The region is famous for its wines, which are grow in the dry Andean foreland that is heavily dependent on meltwater from the mountains. How much of this meltwater is actually stored in ice-rich permafrost landforms is unknown.

As opposed to ice glaciers, rock glaciers show a delayed reaction to a changing climate, as large amounts of debris cover the ground ice, isolating it from rising air temperatures. With large areas located above the lower altitudinal limit of mountain permafrost of ~3600 m.a.s.l., the central Andes of Argentina might store significant amounts of water in the subsurface.

Using mainly near-surface geophysics, our research tries to quantify the water storage capacities in the very abundant and impressive rock glaciers of the region. The Morenas Coloradas rock glacier is of special importance in this regard, as first geophysical measurements date back to the 1980s. Since then, active layer thickness has dramatically increased in the lower parts of the rock glacier, indicating that also the ground ice of the permafrost domain of the central Andes is suffering under the currently warming climate.

A final remark: Thanks goes to the entire team of this research project, namely Christian Halla, Estefania Bottegal, Joachim Götz, Lothar Schrott, Dario Trombotto, Floreana Miesen, Lorenz Banzer, Julius Isigkeit, Henning Clemens, and Thorsten Höser.

By Jan Blöthe, University of Bonn, Germany

Imaggeo on Mondays: Why does a Norwegian glacier look blue?

Imaggeo on Mondays: Why does a Norwegian glacier look blue?

This picture shows the outlet glacier Engabreen running down from the plateau of Svartisen in Norway. Svartisen ice cap comprises two glacier systems of which the Vestre (western) Svartisen is Norway’s second largest glacier. Located right at the polar circle, Svartisen covers a total of 369 km² of the Nordland region. These coastal mountains accumulate a snowpack of 5-7 m depth through the winter season, which feeds the glaciers.

Actually, Svartisen means black ice. However, the ice of the glacier tongue of Engabreen, an outlet glacier of Svartisen ice cap, looks pretty blue in the flat light of a late afternoon in August.  The ice, which is mostly free of air bubbles, transmits the blue colour more than the rest of the visible spectrum of light. Thus, by having to travel a distance of approx. 3 m through the ice body, the blue light is particularly visible.

More than the colour, it is the hydrology and the ice flow of Engabreen which are studied with attention by the Norwegian Water Resources and Energy Directorate (NVE). A tunnel system was built partly underneath the glacier in the 1990’s to collect the waters from Svartisen for hydro power production., The Svartisen Subglacial Laboratory  is located at one end of the tunnel, providing a unique opportunity for direct access to the bed of a temperate glacier. The privileged location means that sub-glacial parameters can be obtained from experiments right at the bottom of a 200 m thick ice pack.

The waters of Holandsfjord have to be crossed to visit the beautiful area of the glacier lake Svartisvatnet and Engabreen. This can be either done by boat shuttle or, as we did, by kayak [ find a magazine article about Kay’s adventure here – in German -].

 By Kay Helfricht, researcher at the Institute for Interdisciplinary Mountain Research of the Austrian Academy of Sciences, Austria

Editor’s note: this text was revised on Tuesday 25th October 2016 following comments from Terje Solbakk.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

 

Imaggeo on Mondays: Glacier de la Pilatte

Imaggeo on Mondays: Glacier de la Pilatte

The relentless retreat of glaciers, globally, is widely studied and reported. The causes for the loss of these precious landforms are complex and the dynamics which govern them difficult to unravel. So are the consequences and impacts of reduced glacial extent atop the world’s high peaks, as Alexis Merlaud, explains in this week’s edition of Imaggeo on Mondays.

This picture was taken on 20 August 2009 at the Pilatte Hutt (44.87° N, 6.33° E,  2572 m.a.s.l.), located in the massif des Ecrins in the French Alps. It shows the Pilatte Glacier, which  was recently described as being 2.64km2 wide and 2.6 km long.

As most of the glaciers in the world, the Pilatte Glacier has been retreating over the last decades as can be seen from the two pictures in figure 1, taken respectively in 1921 and 2003, and from quantitative measurements since the 19th century. The glacier has lost 1.8 km since the end of the Little Ice Age (1850).

Figure 1: Retreat of the Pilatte Glacier over the last decades (pictures adapted from Bonet et al, 2005, time series from Reynaud and Vincent, 2000).

Figure 1: Retreat of the Pilatte Glacier over the last decades (pictures adapted from Bonet et al, 2005, time series from Reynaud and Vincent, 2000).

Two climatic variables affect glacier extents in opposite directions: the amount of winter precipitations (which accumulates snow converting to ice on the glacier) and the summer temperatures (which determines the melting altitude and thus the glacier ablation area – the zone where ice is lost from the glacier, commonly via melting).

The initial retreat of the Alpine glaciers in the 19th century can’t be explained by summer temperatures which remained stable until the 20th century. It has thus been explained by a reduction in snowfall . On the other hand, a recent study suggests that industrial black carbon could have triggered the end of the little ice age in Europe, by reducing the glaciers’albedo. But the globally observed glacier retreat from the 20th century is attributed to the increasing summer temperatures.

Figure 2: Global mean temperature series (Oerlemans, 2005, supporting online material)

Figure 2: Global mean temperature series (Oerlemans, 2005, supporting online material)

Understanding the relationship between glacier dynamics and climate enables to use glacier extents  as proxies to reconstruct global temperature time series, as was done by Oerlemans (2005). Using 169 glacier across the globe, this study provided independent evidences on the timing and magnitude of the warming, that are useful to corroborate other time series obtained through other proxies (such as tree rings) or by direct temperature measurements (see Figure. 2), all showing a temperature increase by around 0.5K across the 20th century.

Glaciers continued to retreat in the 20th century, at an accelerating rate. In the 2015 foreword of the Bulletin of the World Glacier Monitoring Service, its director Michael Zemp writes: “The record ice loss of  the 20thcentury, observed in 1998, was exceeded in 2003, 2006, 2011, 2013, and probably again in 2014 (based on the ‘reference’ glacier sample)”. Using climate models, it appears now possible to distinguish an increasing anthropogenic signature in this phenomenon.

Figure 3: Average glacier retreat worldwide from 1980 in mm of water equivalent (mm.w.e), a unit representing the average thickness of a glacier (WGMS website)

Figure 3: Average glacier retreat worldwide from 1980 in mm of water equivalent (mm.w.e), a unit representing the average thickness of a glacier (WGMS website)

One of the many problems caused by glaciers depletion is the impact on water supplies: glaciers are huge reservoirs of fresh water and their vanishings affect drinking water stock and irrigation for the neighboring population. In the Alps, the idea of replacing the glaciers by dams is already studied. This solution would probably be more difficult to implement in other parts of the world, such as in nothern Pakistan, an area covered with over 5000 glaciers, whose melting is already problematic, causing in particular severe floods.

 

By Alexis Merlaud, Belgian Institute for Space Aeronomy, Brussels, Belgium

References

Bonet, R., Arnaud, F., Bodin, X., Bouche, M., Boulangeat, I., Bourdeau, P., … Thuiller, W. (2015). Indicators of climate: Ecrins National Park participates in long-term monitoring to help determine the effects of climate change. Eco.mont (Journal on Protected Mountain Areas Research), 8(1), 44–52. http://doi.org/10.1553/eco.mont-8-1s44

Ravanel, L., Dubois, L., Fabre, S., Duvillard, P.-A., & Deline, P. (2015). The destabilization of the Pilatte hut (2577 m a.s.l. – Ecrins massif, France), a paraglacial process? EGU General Assembly 2015, Held 12-17 April, 2015 in Vienna, Austria.  id.8720, 17.

Reynaud, L., Vincent, C., & Vincent, C. (2000). Relevés de fluctuations sur quelques glaciers des Alpes Françaises. La Houille Blanche, (5), 79–86. http://doi.org/10.1051/lhb/2000052

Pointer, T. H., Flanner, M. G., Kaser, G., Marzeion, B., VanCuren, R. A., & Abdalati, W. (2013). End of the Little Ice Age in the Alps forced by industrial black carbon. Proceedings of the National Academy of Sciences of the United States of America, 110(38), 15216–21. http://doi.org/10.1073/pnas.1302570110

Vincent, C., Le Meur, E., Six, D., & Funk, M. (2005). Solving the paradox of the end of the Little Ice Age in the Alps. Geophysical Research Letters, 32(9), L09706. http://doi.org/10.1029/2005GL022552

Oerlemans, J. (2005). Extracting a climate signal from 169 glacier records. Science (New York, N.Y.), 308(5722), 675–7. http://doi.org/10.1126/science.1107046

Farinotti, D., Pistocchi, A., Huss, M., al, A. A. et, Barnett T P, A. J. C. and L. D. P., Bavay M, L. M. J. T. and L. H., … Zemp M, H. W. H. M. and P. F. (2016). From dwindling ice to headwater lakes: could dams replace glaciers in the European Alps? Environmental Research Letters, 11(5), 054022. http://doi.org/10.1088/1748-9326/11/5/054022

Marzeion, B., Cogley, J. G., Richter, K., Parkes, D., Gregory, J. M., White, N. J., … Adams, W. (2014). Glaciers. Attribution of global glacier mass loss to anthropogenic and natural causes. Science (New York, N.Y.), 345(6199), 919–21. http://doi.org/10.1126/science.1254702

WGMS (2008): Global Glacier Changes: facts and figures. Zemp, M., Roer, I., Kääb, A., Hoelzle, M., Paul, F. and Haeberli, W. (eds.), UNEP, World Glacier Monitoring Service, Zurich, Switzerland: 88 pp

 

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/

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