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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: Airplane views of the Alps

Imaggeo on Mondays: Airplane views of the Alps

The forward scattering of sunlight, which is caused by a large number of aerosol particles (moist haze) in Alpine valleys, gives the mountain massifs a rather plastic appearance.

The hazy area in the foreground lies above the Koenigsee lake; behind it the Watzmann, Hochkalter, Loferer Steinberge and Wilder Kaiser massifs loom up behind one other to the right of the centre line. Behind them is the wide Inn valley, which extends right across the picture. In the far distance in the middle of the picture, the Wetterstein massif projects upwards with the Zugspitze mountain as its highest peak.

The left side shows Steinernes Meer, Leoganger Steinberge and a sequence of at least 10 mountain chains that extend as far as Kellerjoch, which is in front of the whitish area of haze above Innsbruck. The noon sounding from Munich showed that relative humidity exceeded 75% up to 1,400 m above sea level, with distinctly lower values above (less than 20 %).

The view is from an aircraft window approximately 10 km to the east of the Salzach valley.

Description by Hans Volkert, as published previously on imaggeo.egu.eu

February GeoRoundUp: the best of the Earth sciences from around the web

Comparing the TRAPPIST-1 planets

Drawing inspiration from popular stories on our social media channels, as well as  unique and quirky research news, this monthly column aims to bring you the best of the Earth and planetary sciences from around the web.

Major story

Undoubtedly the story of the month is the discovery of a star system of seven Earth-sized planets just 40 light-years away from our own. What makes the finding so exciting is that three of the planets lie in the habitable zone. All could have oceans and atmospheres, making them good candidates to search for extraterrestrial life.

The seven Earth-sized worlds orbit the ultra-cool dwarf star, TRAPPIST-1, which has been known to astronomers for some time. As the planets passed in front of TRAPPIST-1, the star’s light output dipped. Using a combination of ground and spaced based telescopes, the changes in the light output were used to detect the planets and gather information about their size, composition and orbit, explains the press release by the European Southern Observatory.

This simple GIF by New Scientist illustrates the principle of how the remarkable planets were found (while at the same time highlighting the fact there is a mind-blowing number of exoplanets scattered throughout space!).

The ultra-cool dwarf star and its planetary system has an even cooler website, which comes complete with great posters, videos, short stories, poems and graphic novels; as well as a detailed timeline of all the years of work which took place behind the scenes and culminated in the announcement made earlier this month.

Our top pick for a science poem honouring the discovery is In Search of New Life by Sam Illingworth, a lecturer at Manchester Metropolitan University.  You can also find an audio version of the poem here.

Far into space, amongst the darkest Sea

New planets sit like marbles in a row.

We turn our eyes to find out what might be

And search for patterns in their ether’s flow;

Then try to see what else might lie below.

And as we probe how life’s rich web was spun,

Do they look back towards our distant sun?

 

What you might have missed

The discovery of a previously unknown continent below New Zealand and New Caledonia dominated headlines towards the middle of the month.

Dr. Mortimer, of GNS Science and lead author of the study, argues that “being more than 1 million square kilometers in area, and bounded by well-defined geologic and geographic limits, Zealandia [the name given to the newly discovered continent] is, by our definition, large enough to be termed a continent.”

But without an official authority which designates the existence of continents, it will be for the broader scientific community to recognise Zealandia as one. And the jury is still out, as Alex Witze finds in this Nature News & Comment article:

“Claiming that Zealandia is a continent is a bit like stamp collecting,” says Peter Cawood, a geologist at Monash University in Melbourne, Australia. “So what?”

While the (potentially) new Antipodean continent dominated headlines, you might have missed the discovery of another lost continent. Deep under the waters of the Indian Ocean, sandwiched between Madagascar and India, lie the scattered pieces of an ancient, drowned, microcontient called Mauritia. The authors of the study, published earlier this month in Nature Communications, dated zircons of up to 3 billion years old from Mauritanian volcanic rocks. Considering Mauritania is much younger, the researchers argue the zircons must have come from another, already existing continent.

Meanwhile, in the southern-most reaches of our planet, a huge iceberg is set to breakaway from the Larsen C Ice Shelf, on the northeastern coast of the Antarctic Peninsula. A large crack in the ice was spotted in natural-colour satellite imagery captured by NASA back in August 2016. Int January 2017 alone, the crack grew by more than 10 km in length and now stretches 175 km over the ice.

British Antarctic Survey (BAS) scientists recently captured footage of the huge crack. The video highlights what the calving of such a large iceberg might mean for the Larsen C ice shelf, while this Nature News and Comment story highlights how far glaciology has come since similar calving events in the 90s and 00s. Scientists now have a much better understanding of what might happen in the weeks and months to come.

Five links we liked

The EGU story

After long-awaited snowfall in January, parts of the Alps are now covered with fresh powder and happy skiers. But the Swiss side of the iconic mountain range had the driest December since record-keeping began over 150 years ago, and 2016 was the third year in a row with scarce snow over the Christmas period. A study published this month in The Cryosphere, a journal of the European Geosciences Union, shows bare Alpine slopes could be a much more common sight in the future.

The new research, by scientists based at the Institute for Snow and Avalanche Research (SLF) and at the CRYOS Laboratory at the École Polytechnique Fédérale in Switzerland, shows that the Alps could lose as much as 70% of snow cover by the end of the century. However, if humans manage to keep global warming below 2°C, the snow-cover reduction would be limited to 30% by 2100.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

Imaggeo on Mondays: Glarus Alps

Undoubtedly, the Alps are one of the best studied mountain ranges in the world. Appreciating their immense beauty and geological wealth can be difficult from the ground, given their vast scale and the inaccessibility of some of their more challenging peaks. Kurt Stüwe, along with alpine photographer Ruedi Homberger, set about changing this by undertaking the ambitious task of photographing the length of the Alps, from Nice to Vienna, in a small aircraft. The result is a compilation of stunning photographs that capture the magnificence of the Alps and contribute to a better understanding of their geological history.

Glarus Alps. (Credit: Kurt Stüwe, via imaggeo.egu.eu

Glarus Alps. (Credit: Kurt Stüwe, via imaggeo.egu.eu)

The photo shows the Bifertenstock in the Glarus Alps looking east. The region in the middle ground is part of the “Tectonics Arena Sardona“, which is a UNESCO nature world heritage region featuring also the Glarus Thrust – arguably the most famous structure in the Alps. The rocks in the foreground of the picture are part of the Mesozoic (spanning ages between 252 and 66 million years ago) cover sequence that overlies the Variscan gneisses of the Aare Massif in eastern Switzerland. The 300 million year old Variscan gneisses can be seen in the lower reaches of the photograph on both sides of the mountain in the Linth valley (at left) and Rhine valley (at right). The distinctly orange dolomite (sedimentary carbonate rocks) bed separates gneisses from marine sediments.

In much of the Alps, the onset of deposition of Mesozoic sediments onto the Palaeozoic (Variscan) gneisses in the Permian and Triassic was the beginning of a prolonged period of sedimentation that lasted almost 200 million years until the Eocene. The sedimentation was the consequence of slow continuous cooling and thickening of the mantle part of the Adriatic lithosphere following dramatic lithospheric thinning events in the Permian. In the Jurassic this thickening ultimately led to negative buoyancy of the entire continental lithosphere and thus to the onset of intracontinental subduction inside the Adriatic plate. As such, the Mesozoic sedimentation may be viewed as the trigger of the Alpine orogenic cycle. In other parts of the Swiss Alps, these sediments were late sheared off their own basement and transported north forming the famous Helvetic nappes of Switzerland.

The photo was taken as part of a multiyear project in which the entire Alpine chain was photographed from a geological perspective from a two seated Piper Supercub aircraft. The present photo was taken on a late afternoon while returning from a photo flight in the Bernese Oberland back to Arosa. You can see more photos from the project on the project website.

Helvetic Nappes of Switzerland. (Credit: Kurt Stüwe, via imaggeo.egu.eu)

Helvetic Nappes of Switzerland. (Credit: Kurt Stüwe, via imaggeo.egu.eu)

 

By Prof. Dr. Kurt Stüwe, Earth Sciences Department, Graz University, Austria.

Reference

Schster, R. & Stüwe, K., Permian metamorphic event in the Alps, Geology, 36,8, 603-606, 2008

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

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