Pure water (H2O) converts into a solid form at a temperature of 0 °C – it freezes into ice. Contrary to other liquids, water expands when freezing and increases its volume by approx. 9 %. Ice, therefore, has a lower density than water (it is lighter) which explains why it floats on the water’s surface. The freezing point is below 0 °C if salt or other substances are dissolved in water. For this reason salt is used on the roads in winter to help prevent black ice. Ice can be found on earth in all manners of shapes and forms: in polar ice streams, icebergs in the sea, alpine glaciers, hexagonal snowflakes, hailstones, frost on windows, frozen waterfalls, rivers and lakes … The uppermost molecules of ice are only loosely connected. Thanks to this “liquid” surface it is possible to ski, ice skate, form snowballs and build igloos. It is only at temperatures of -60 °C and colder that the ice surface becomes viscous. Apart from its’ physical characteristics, ice possesses amazing expressive qualities. The infinite varying shades of aquamarine are an amazing visual experience,which leaves the question, why is ice so “blue”? All colours of the rainbow are absorbed by ice except the colour blue, which is reflected, thus creating the fascinating visual impression of a glacier actually being blue.

Even though most of us live far away from „icy“ areas, the world is actually an icy planet! Up to 11 % of the earth’s surface area is covered by glaciers and almost a quarter is covered by a mantle of snow for longer than 4 months of the year. In total, 91 %of the world’s ice can be found in the Antarctic and 8 % in Greenland. All glaciers worldwide add up to only 1 % of the entire ice mass of the world! Glaciers can be found anywhere on earth – from the North and South Poles to the Equator. In the equatorial belt in Africa glaciers can be found for example at Kilimanjaro, Mount Kenya and in the Rwenzori Mountains, which are all mountain ranges with heights of over 5,000 metres above sea level. At the North and South Poles it is cold enough for glaciers to exist at sea level. In South America there are many glaciers in the tropical Andes. Furthermore, on the second largest island of the world, Papau New Guinea (north of Australia) glaciers can be found on the 5,000 metre high Mount Puncak Jaya. The Lambert Glacier in East Antarctica is the largest glacier, or ice stream, in the world spanning over 400 km in length and almost 50 km wide. The largest glacier outside of Greenland and the Antarctic is the Vatnajökull (or the Glacier of Rivers) in Iceland. With a surface area of over 8,000 km², it is 2/3 of the size of Tyrol (12,648 km2) and approx. 70 times the size of the largest glacier in the Alps, the Aletsch Glacier (117 km2, Switzerland). The largest glacier in Austria is the Pasterze at Großglockner, which is approx. 18,5 km2. Germany’s largest glacier is the Schneeferner on the Zugspitze, which covers a surface area of around 50 hectares.

 

Glaciers are ice streams and ice sheets respectively which are nourished, or rather an accumulation of ice, which occurs in high mountain ranges or Polar areas situated above the snow line, where more precipitation falls in a solid form per year than
actually melts. As more and more snow builds up in winter, the weight of the snow on top starts to compress the snow on the bottom, turning the underlying snow to ice. The top layer of snow repeatedly melts in summer, forcing water to penetrate between the ice crystals which, in part, freeze again. This process of ice crystals repeatedly melting and refreezing transform the ice into what is known as “Firn snow” and then eventually, glacial ice. The existence and survival of glaciers depends long term on a fine balance sustenance. In the accumulation area more snow remains lying on the ground than actually melts. After about 10 years the compacted crystals of Firn snow turn into watertight ice. The former snow now has a density of approx. The many layers of compressed ice formed over numerous summers and winters are very flexible (scientists use the term plastic) and gravitational forces propel the glacier downhill, between the sides of a mountain. The lower ege of the glacier is called the ablation area, where temperatures are warmer and more snow and ice melts than accumulates. A glacier with a much larger average accumulation area is growing. Surprisingly, air temperature in summer is not a decisive factor regarding glacial melt – up to two thirds is caused by natural radiation! Rocks ranging in a size of approx. 15 cm and upwards actually protect the glacier from solar rays. Smaller stones are heated up by the sun and sink into the top layer of ice forming cylindrical melt holes, known as cryoconite holes. For this reason it is very important that it snows often in summer on glaciers, so the glacier surface is white and damaging sun rays are reflected.

At first glance, ice appears to be an inflexible entity. If this was the case and ice was frozen solid underground, year after year more ice would accumulate on mountains, as well as the North and South Poles, meaning that glaciers would continually grow in size. In fact, glaciers “flow” down the mountain through a glacial valley. This is also true of the Hintertuxer Glacier An ice particle in the accumulation area will migrate deeper into the glacier, as more and more snow builds up over the years. The “ice flow” then continually transports it valley downwards where, after many years, it will eventually surface in the ablation area during
the annual thaw. The higher up an ice particle begins its glacial journey, the longer it takes before it comes out on “the other side”. For this reason the oldest ice is always found at the front end of a glacier, known as the “terminus”. Furthermore, stones and other materials that fall on a glacier will also eventually emerge at the glacier terminus. The duration of an ice particle‘s journey from the Firn region to terminus of an alpine glacier depends on the size of the glacier and can range from anything between 100 to 1,000 years! In Greenland snow crystals are ensnared in ice for up to 100,000 years and in the Antarctic for up to 400,000 years! The ice at the Hintertuxer Glacier is between 500 and 1,000 years old. The measuring of glacial flow was stigated in Switzerland and Austria approximately 100 years ago. According to the size of the glacier and climate conditions, alpine glaciers shift between 1 m and 200 m annually. Glaciers in Greenland and the Antarctic can move thousands of metres per year! Although small in comparison, shifts of up to 60 metres per year have been measured at the Hintertuxer Glacier. The Kuhtiah Glacier in Pakistan holds the record for the fastest glacial surge in the world. In 1953 it raced more than 12 km in 3 months, averaging about 112 metres per day! If a great deal of snow falls during winter in the accumulation area, glacial flow speed will subsequently increase in the following year.

 

Glaciers move at varying speeds depending on the underlying terrain; for example over rocky ridges or around corners. These accelerations in glacier speed cause tension and can initiate a crevasse at or near the glacier‘s surface. The depth of the crevasse depends on the overlaying pressure exerted. The maximum depth of a dry crevasse in alpine glaciers is usually about 30 metres. Commonly referred to as A or V crevices, there are in fact only V crevices. These are wider at the top and close together at the bottom forming a V shape, reaching depths of approx. 30 metres. Experience shows that an A form is usually a
snow-covered crevice with an apparently narrow opening which, on inspection, gives the impression of being much wider below the surface. In fact, snow or the Firn layers covering the crevice entrance give the misleading impression of the opening being narrower than it actually is.

Climate changes have been going on since the beginning of time and extreme temperature changes have been occurring worldwide for millions of years. Drawing on scientific evidence using ice core data from Greenland and the Antarctic, we know that our planet has been and will be affected approximately every 100,000 years by a recurring Ice Age. The last glacial epoch culminated approx. 20,000 years ago, when average temperatures were around. 8 °C less than those of the present day. During this time inhabiting the Alps would have been absolutely inconceivable! Ice streams of up to 2,000 metres in depth were
inexorably forcing their way through alpine valleys carving, amongst others, the Hintertuxer Glacier and the Tuxer Valley into their present day form. The Olperer (3,476 m) was at that time ice free, due to the thence prevailing strong and dry winds.
During the last 11,000 years the majority of alpine glaciers were actually smaller than they are at present. Proof of this is remnants of trees which have emerged during thaws at the glacier terminus. It is entirely conceivable that these areas, now filled by the snout of a majestic glacier, were once thick forests of larch and pine trees. At around the time of the birth of Christ the Medieval Warm Period (MWP), otherwise known as the Medieval Climate Optimum occurred, which was a 1,000 year period of unusually warm weather. During these mild climatic times the Roman Empire and wine growing regions stretched as far as Great Britain. This was followed by a distinctly cold phase, and led to the well documented Germanic Migration Period. Around 900 AD the climate changed once again for the better and turned warmer. This warm period ended at around the 15th Century which marked the beginning of the “Little Ice Age”. The Little Ice Age (between the 15th and 19th Centuries) was characterized by a relatively cold climate during which Europe was dominated by incredibly cold winters. Even the English Thames and Dutch canals were frozen for long periods of time. In the middle of the 17th century Alpine glaciers forged their way down valley beds, threatening farm lands and settlements. This continued until around 1850, when the alpine glacier levels peaked and from then on have been gradually receding. Still visible in Hintertux today are imposing lateral moraines (parallel ridges of debris deposited along the sides of a glacier) stretching well down into the valley. This is impressive natural documentation of the magnitude of the glacier during this period.

In Austria there are around 840 virtually untouched glaciers. Only relatively small glaciers with little ice movement and not a great deal of crevice formation are suitable for building ski lift systems on. The extremely complex construction work and the difficulties associated with mounting the lift supports on an ice base, which must then be moved several times a year due to shifting ice, are reason enough to think twice before embarking on such a project. At present in Austria there are ski lifts on 8 glaciers which provide glacier skiing, 5 of which are situated in Tyrol. Of these, the Hintertuxer Glacier is the only glacier ski region open to skiers and boarders all year round – even in summer! The annual precipitation in Tyrol is approximately equal to the amount of all the water stored in Tyrol’s glaciers. These glacial waters cannot be considered, however, as a drink water reservoir, as the water itself is lacking in mineral nutrients and untreated, is not suitable for human consumption.