CR
Cryospheric Sciences

The Alps

Image of the week – Skiing, a myth for our grandchildren?

Image of the week – Skiing, a myth for our grandchildren?

Ski or water ski? Carnival season is typically when many drive straight to the mountains to indulge in their favorite winter sport. However, by the end of the century, models seem to predict a very different future for Carnival, with a drastic reduction in the number of snow days we get per year. This could render winter skiing something of the past, a bedtime story we tell our grandchildren at night…


Christoph Marty and colleagues investigated two Swiss regions reputed for their great skiing resorts and show that the number of snow days (defined as a day with at least 5 cm of snow on the ground) could go down to zero by 2100, if fuel emissions and economic growth continue at present-day levels, and this scenario is less dramatic than the IPCC’s most pessimistic climate change scenario (Marty et al., 2017). They show that temperature change will have the strongest influence on snow cover. Using snow depth as representative for snow volume, they predict that snow depth maxima will all be lower than today’s except for snow at elevations of 3000 m and higher. This implies that even industrially-sized stations like Avoriaz in the French Alps, with a top elevation of 2466 m, will soon suffer from very short ski seasons.

Marty et al. (2017) predict a 70% reduction in total snow volume by 2100 for the two Swiss regions, with no snow left for elevations below 500 m and only 50% snow volume left above 3000 m. Only in an intervention-type scenario where global temperatures are restricted to a warming of 2ºC since the pre-industrial period, can we expect snow reduction to be limited to 30% after the middle of the century.

Recent work by Raftery et al (2017) shows that a 2ºC warming threshold is likely beyond our reach, however limiting global temperature rise, even above the 2ºC target, could help stabilize snow volume loss over the next century. We hold our future in our hands!

Further reading/references

  • Marty, C., Schlögl, S., Bavay, M. and Lehning, M., 2017. How much can we save? Impact of different emission scenarios on future snow cover in the Alps. The Cryosphere, 11(1), p.517.
  • Raftery, A.E., Zimmer, A., Frierson, D.M., Startz, R. and Liu, P., 2017. Less than 2 C warming by 2100 unlikely. Nature Climate Change, 7(9), p.637.
  • Less snow and a shorter ski season in the Alps | EGU Press release

Edited by Sophie Berger


Marie Cavitte just finished her PhD at the University of Texas at Austin, Institute for Geophysics (USA) where she studied the paleo history of East Antarctica’s interior using airborne radar isochrone data. She is involved in the Beyond EPICA Oldest Ice European project to recover 1.5 million-year-old ice. She tweets as @mariecavitte.

Image of The Week – A Game of Drones (Part 1: A Debris-Covered Glacier)

Image of The Week – A Game of Drones (Part 1: A Debris-Covered Glacier)

What are debris-covered glaciers?

Many alpine glaciers are covered with a layer of surface debris (rock and sediment), which is sourced primarily from glacier headwalls and valley flanks. So-called ‘debris-covered glaciers’ are found in most glacierized regions, with concentrations in the European Alps, the Caucasus, Hindu-Kush-Himalaya, Karakoram and Tien Shan, the Andes, and Alaska and the western Cordillera of North America. Debris cover is important for ice dynamics for several reasons:

  • A layer of surface debris thicker than a few centimetres suppresses ice ablation (Brock et al., 2010), as it insulates the underlying ice from atmospheric heat and insolation.
  • In contrast, a thin layer of debris serves to enhance melt rates through reduced albedo (reflectance) and enhanced heat transfer to underlying ice.
  • A continuous or near-continuous layer of debris can result in debris-covered glaciers persisting at lower elevations than, and attaining lengths which exceed those of their ‘clean ice’ counterparts (Anderson and Anderson, 2016).

Miage Glacier – the largest debris-covered glacier in the European Alps

The Ghiacciaio del Miage, or Miage Glacier, is Italy’s longest glacier and is the largest debris-covered glacier in the European Alps. It is situated in the Aosta Valley, on the southwest flank of the Mont Blanc/Monte Bianco massif. The glacier descends from ~3800 m to ~1700 m above sea level (a.s.l.) across a distance of around 10 km, and is fed by four tributary glaciers. The glacier surface is extensively debris-covered below ~2400 m a.s.l., and the average surface debris thickness is 0.25 m across the lower 5 km of the glacier (Foster et al., 2012).

 

Figure 2: Up-glacier view of Miage Glacier, in which three of the glacier’s four tributaries are visible – from upper centre-left: Tête Carée Glacier, Bionnassay Glacier, Dome Glacier.

Figure 2: Up-glacier view of Miage Glacier, in which three of the glacier’s four tributaries are visible – from upper centre-left: Tête Carée Glacier, Bionnassay Glacier, Dome Glacier.

Glacier surveying using Unmanned Aerial Vehicles

Researchers from Northumbria University, UK, acquired these images of the glacier using a lightweight unmanned aerial vehicle (UAV) during a recent field visit to Miage Glacier. During the visit the team carried out a range of activities including the installation and maintenance of a network of weather stations and temperature loggers across the glacier and geomorphological surveying of the glacier and its catchment, whilst undergraduate students collected data for their final-year research projects. The UAV imagery reveals the emergence of surface debris cover from beneath winter snow cover and the persistence of a channelized hydrological network in the snowpack, characterised as a cascade of streams and storage ponds. A recent study by Fyffe et al. (2015) found that high early-season melt rates and runoff concentration in intermoraine troughs promotes the development of a channelized subglacial hydrological system in mid-glacier areas, whilst the drainage system beneath continuously debris-covered areas down-glacier is largely inefficient due to lower melt inputs and hummocky topography.

(Edited by Emma Smith and Sophie Berger)


Matt Westoby is a postdoctoral researcher at Northumbria University, UK. He is a quantitative geomorphologist, and uses novel high-resolution surveying technologies including repeat UAV-based Structure-from-Motion to quantify surface processes and landscape evolution in glacial and ice-marginal environments. Fieldwork on the Miage Glacier in June 2016 was supported in part by an Early Career Researcher Grant from the British Society for Geomorphology. He tweets as @MattWestoby Contact e-mail: mjwestoby@gmail.com

Image of The Week – Tumbling Rocks

Image of The Week – Tumbling Rocks

This photo captures a rockfall at the summit of Tour de Ronde, 3792 m above sea level in the Mont Blanc Massif. On 27 August 2015, around 15000 m3  of rock fell from the steep walls of the mountain.

Why do mountains crumble ?

Rockfalls such as the one on the photo have been linked to thawing permafrost. The exact mechanism that leads to these events is not fully understood, however, it is thought that areas of the mountain becoming destabilised during thaw periods (Luethi et al, 2015). Records show that during heat waves — as for instance the one that happened in the summer of 2015 in the Mont Blanc Massif — there are many more rockfalls than during colder years. Researchers at the Université Savoie Mont Blanc have been monitoring this area of the Alps for many years, installing a network of temperature sensors on the surface and in boreholes drilled into the rock to try and better understand the link between temperature and rock slope stability (see Magnin et al, 2015).

What can we do about it? 

The short answer is that there is not a lot that can be done to prevent it. However, long term monitoring studies, such as the one from Magnin et al (2015), help to better understand what conditions are likely to result in rockfall activity and therefore predict when they are likely to happen. By doing this in the Mont Blanc region the team from Université-Savoie Mont Blanc has been able to put in place an alert network to warn the local community to increased rockfall activity. This means that the potential damage can be minimised, for example, by closing climbing routes in risky areas.


Further reading

Check out our blog post about how cryospheric research can transform lives.

  • Magnin, F., Deline, P., Ravanel, L., Noetzli, J., and Pogliotti, P. (2015) : Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l), The Cryosphere, 9, 109-121, doi:10.5194/tc-9-109-2015
  • Luethi, R., Gruber, S. and Ravanel, L., (2015) Modelling transient ground surface temperatures of past rockfall events: towards a better understanding of failure mechanisms in changing periglacial environments. Geografiska Annaler: Series A, Physical Geography, 97, 753767. doi: 10.1111/geoa.12114

Edited by Emma Smith and Sophie Berger

Image of the Week — Last Glacial Maximum in Europe

Image of the Week — Last Glacial Maximum in Europe

During the last ice age*, ~70,000 to 20,000 years ago, the climate was much colder in Europe.

As a result, the northern part of Europe was fully covered by the Fennoscandian (a.k.a the Scandinavian ) ice sheet, which extended up to the British Isles and some parts of Poland and Germany. In central Europe, the Alps were also almost fully glaciated.

The storage of all this ice on the continent lowered the sea level (seedark green), which substantially reduced the extent of the North Sea.

*This period is referred to as the Weichselian glaciation and the Würm glaciation in Northern Europe and the Alps, respectively.

 

More information

A more complete and accurate dataset (including GIS maps) of Europe during the last glacial maximum is freely available :

Becker, D., Verheul, J., Zickel, M., Willmes, C. (2015): LGM paleoenvironment of Europe – Map. CRC806-Database, DOI: http://dx.doi.org/10.5880/SFB806.15

LGM_Europe_Map_v1

 

Image of the Week: Under a Glacier

Image of the Week: Under a Glacier

What is happening under a glacier? This is a difficult questions to answer as accessing the glacier bed is usually not that easy. Here, we are getting a rare glimpse of the different processes and materials that are often found at the ice-bed interface. The photograph shows both sediments and hard rock, clear ice and dirty ice, and of course flowing water. No wonder these processes are complicated to say the least!

The photo was taken by Ilkka Matero (University of Leeds, U.K) during the excursion to Hochjochferner at the Karthaus summer school. See also the Image of the Week post from 18th of September to get an outside view of the side of the glacier.

Image of the Week: Hochjochferner

Image of the Week: Hochjochferner

The margin of the glacier “Hochjochferner” on the border between Austria and Italy. This glacier has been monitored with an Automatic Weather Station for several years by the Institute for Marine and Atmospheric research in Utrecth, NL.It is also the destination of the field trip that takes place during the annual Karthaus summer school in ice and climate. Here, students are exploring the margin of the glacier, where the sound of water rushing under the ice could clearly be heard.