Aletsch Glacier
The Aletsch Glacier () or Great Aletsch Glacier () is the largest glacier in the Alps. It has a length of about (2014), has about a volume of (2011), and covers about (2011) in the eastern Bernese Alps in the Swiss canton of Valais. The Aletsch Glacier is composed of four smaller glaciers converging at Konkordiaplatz, where its thickness was measured by the ETH to be still near . It then continues towards the valley before giving birth to the Massa. The Aletsch Glacier is – like most glaciers in the world today – a retreating glacier. As of 2016, since 1980 it  lost of its length, since 1870 , and lost also more than of its thickness. The whole area, including other glaciers is part of the Protected Area, which was declared a UNESCO World Heritage Site in 2001. Geography. The Aletsch Glacier is one of the many glaciers located between the cantons of Bern and Valais on the Bernese Alps located east of the Gemmi Pass. The whole area is considered to be the largest glaciated area in western Eurasia. The Fiescher and Aar Glaciers lying on the east have similar extensions. Except the , all the highest summits of the Bernese Alps  are located within the drainage basin of the glacier. The and constitute the northern boundary; the and lie on its east side; finally the culminating point, the () is located on the west side. Before reaching the maximum flow, three smaller glaciers converge at Konkordiaplatz: South of Konkordiaplatz, the glacier runs towards the valley of the (Upper Valais); on the east side, near , lies a small glacier lake, (); from the western side used to enter the , but since the end cof the 20th century the connection with the Aletsch Glacier has been lost. Further down, until about 1880, the did also  enter the Aletsch Glacier at its mouth. But since then both glaciers have been retreating so far that they do not connect anymore (the Upper Aletsch Glacier did retreat about from its connecting point with the Aletsch Glacier), but both serve now only as the source of the river Massa. The river flows through the Lake (a reservoir, and coincidentally representing the glacier's mouth region in the 19th century, which is a retreat of more than ) and a gorge of the same name before reaching the near . Tourism. The area of the Aletsch Glacier and some surrounding valleys is  on the UNESCO World Heritage list, thus it is protected and the facilities are mostly restricted to the external zones. The region between , and (which is called "Aletsch Region") in Valais gives access to the lower part of the glacier. The and are popular view points and are accessible by cable car. The river can be crossed since 2008 by a suspension bridge, thus allowing hikes between the left and the right part of the glacier. The railway station (3,450 m) gives a direct access to the upper Aletsch Glacier as well as the normal route to the . It can  be reached only from in the canton Bern. Hiking paths pass the Hut or the Hollandia Hut, eventually reaching other glaciers in the massif. On the , at 2,065 metres between and the glacier, is located the historic Villa Cassel, former summer residence of many famous and influential guests from the worlds of politics and finance. The house is now one of the centers of the environmental organization Pro Natura, which hosts a permanent exhibition about the site. Panorama. Also at the mouth of the from the east is the small but important (3 km long and averaging 600 m wide ). This firn is connected in the over the glacier pass (3280 m high) to the Glacier in the east. From the , the Aletsch Glacier has a width of approximately 1.5 km and moves at a rate of 180 m per year to the southeast on course with the valley, bordering the in the west and the great in the east. It then takes a great right turn and bends ever closer to the southwest, running through the edge of the and of the Rhône valley. The lowest part of the great Aletsch Glacier is largely covered with detritus of the  lateral and medial moraines. The glacier's toe currently lies about 1560 m high, far beneath the local tree line. From it springs the Massa stream, which flows through the Massa Canyon and is used to generate hydroelectric power. It continues through the upper half of the , eventually entering into the . The great Aletsch Glacier shows considerable ice cover. At the Konkordiaplatz, it has an ice cover of more than 900 m, but as it moves to the south, the greater part of the ice melts, gradually decreasing the cover to around 150 m. The characteristically dark medial moraine, situated  almost in the middle of the glacier, runs protracted in two bands from the along the whole length to the glacier's toe-zone. This medial moraine is collected from the ice of three large ice fields, which all run together. The westernmost medial moraine has been named the , and the easternmost carries the name . Formation and evolution. The Aletsch Glacier resulted from the accumulation and compaction of snow. Glaciers generally form where snow and ice accumulation exceed snow and ice melt. As the snow and ice thicken it reaches a point where it begins to move due to a  combination of gravity and pressure of the overlying snow and ice. During the last glacial periods, the Aletsch Glacier was much larger than now. 18,000 years ago the lower part of the ridge, between and the glacier, was completely covered by ice. Only the summits of the , and the were above the glacier. After an important retreat, the glacier again advanced 11,000 years ago during the last glacial period. The glacier reached the Rhône valley, and its ice the . Remaining moraines are still visible in the Aletsch Forest. Since the last glaciation, the glacier generally retreated. However slight climatic changes  happened and, in 1860, the glacier was 3 km longer and the ice level 200 m higher. As for many other glaciers, records show a major longer-term retreat trend. The Aletsch Glacier receded by since 1870, including since 1980. A record retreat of happened in 2006 alone. Since the end of the Little Ice Age in 1850 the glacier has lost 20 percent of its ice mass, considerably less than other glaciers in Switzerland, which have lost up to 50 percent. This is explained with the large size of the Aletsch Glacier, which reacts much slower to climate change  than smaller glaciers. It is however estimated that, by 2100, the glacier will have only one tenth of its 2018 ice mass. Photo opportunity. On August 18, 2007, photographer Spencer Tunick used hundreds of naked people in a "living sculpture" on the Aletsch Glacier in a photo shoot which he said was intended to draw attention to global warming and the shrinking of the world's glaciers. The temperature was about 10 °C (50 °F) at the time of the photo shoot. The 600 participants on the shrinking glacier said that they had volunteered for Tunick (a collaboration  with Greenpeace) to let the world know about the effects of global warming on the melting Swiss glaciers.