Antarctic Ice Sheet

The Antarctic Ice Sheet (also known as the Antarctic Ice Sheet) is one of the two polar ice caps. It is the largest independent mass of ice on earth and almost completely covers the Antarctic continent (Antarctica). The area of the ice sheet is estimated at 13.856 million square kilometers, the ice volume at 26.37 million cubic kilometers (as of 2005).[4] A value of 2.16 km is assumed for the average ice thickness, the maximum known ice thickness was measured at 4776 meters in Adélieland.[5] A more recent measurement/estimate (as of 2013) indicates a surface of the ice sheet of 13.924 million km² and a volume of 26.92 million km³.[6]

 

icebergs

Typical of the Antarctic are gigantic tabular icebergs that regularly break off from ice shelves or glaciers and can travel thousands of kilometers adrift at sea. It can take several years for a large iceberg to completely melt; however, it can easily break apart into several small ones, for example due to differential ocean currents. This longevity of large icebergs also provided the basis for futuristic projects to transport them to Africa or other dry areas as freshwater storage, for example with tugboats.

On April 30, 1894, an iceberg was sighted in the middle of the Atlantic Ocean at ♁26° 30′ S, 25° 40′ W (southeast of the Brazilian island of Trindade, which is approximately at the latitude of Joinville); it was the northernmost position of an Antarctic iceberg ever recorded.

 

seas

Antarctica is surrounded by the Southern Ocean. There are a number of marginal seas near the coast, including:

• Lake Amundsen

• Bellingshausensee

• davis lake

• McMurdo Sound

• Ross Sea

• Weddell Sea

 

ice shelf areas

Much of the Antarctic coast is made up of ice shelves. The two largest ice shelves, the Filchner-Ronne Ice Shelf and the Ross Ice Shelf, each cover an area larger than Germany. Another large ice shelf is the Larsen Ice Shelf on the east coast of the Antarctic Peninsula.

 

volcanoes

Mount Erebus in Antarctica is the southernmost active volcano on earth. The area between the Antarctic Ross Ice Shelf and the Antarctic Peninsula is said to have one of the highest volcanic densities on earth (-> subglacial volcano). As of 2017, 138 Antarctic volcanoes were known, but many more are suspected. Due to the ice sheet, which is on average 2 km thick, volcanic eruptions are hardly recognizable from outside.

 

Flora and fauna

The Antarctic continent is surrounded by a vast zone of pack ice, which has developed one of the most lush ecosystems in the world due to the oxygen-rich water. The seas are teeming with huge schools of Antarctic krill (Euphausia superba) and other small crustaceans. These krill form the beginning of the food chain for numerous marine and terrestrial animals such as fish, whales, squid, eared seals, harbor seals, penguins and numerous seabirds.

As a result of the increasing melting of the polar ice caps in the course of man-made global warming, typical pioneer plants such as mosses are finding ever better living and development conditions on the increasingly numerous and frequently exposed land areas.

 

flora

In contrast to the diverse life in the oceans and on the ice shelf margins, the few ice-free regions, which are also known as Antarctic oases and which are located in the interior of Antarctica, appear barren and empty, since hardly any highly developed life forms are found here. Instead, these areas are predominantly populated by microorganisms, mosses and lichens and some invertebrates. There are only two flowering plants in all of Antarctica: the Antarctic hairgrass (Deschampsia antarctica) and the clove family Antarctic pearlwort (Colobanthus quitensis). However, the creeping buttercup, the water sedge, the meadow grasses Poa annua and Poa pratensis and the chickweed were also introduced by humans. In addition to various algae, more than 200 species of lichen, more than 100 species of moss and liverworts and about 30 macrofungi have now been found.

Antarctica forms its own floral kingdom, the Antarctic floral kingdom. It includes the South Island of New Zealand, the south-western part of Patagonia and the Antarctic continent and is home to thirteen different plant genera, such as the southern beech (Nothafagus), Gunnera or Fuchsia, most of which are not native to Antarctica itself.

 

life under the ice

Special ecosystems comparable to those found in the groundwater habitat were found in the subglacial lakes under the Antarctic ice sheet, which have now (2020) been examined sporadically.

At the beginning of 2021, research reports were published according to which "sedentary marine life" was found "completely surprising" and "absolutely unexpected" during an ice drilling under the approx. 1 km thick layer of ice of the Filchner-Ronne Ice Shelf, the "second largest permanent ice sheet in Antarctica". , in complete darkness, with a water temperature of about 2 °Celsius.

In East Antarctica, at times highly saline, initially transparent brine (two to three times as salty as seawater) flows out of crevices in a glacier tongue: if it comes into contact with atmospheric oxygen, the heavily enriched iron in it oxidizes, it "rusts" and turns the water blood red, the so-called "Blood Falls". It is suspected that this could be the outflow of a large-scale subglacial aquifer in which the water flows very slowly. Given its chemical composition, it could be very old and isolated from the outside world for millions of years. The strong lye contains no oxygen and remains liquid even at minus 7 °Celsius. It is home to highly specialized bacteria of fewer species ("rod- or spherical") related to marine microorganisms, which may indicate earlier, warmer times in the area, when the Antarctic Ocean was still deep in the valleys of the Antarctic continental shelf (-> fjord).

 

mammals

There are only marine mammals in Antarctica, such as seals and whales. The seal species found in Antarctica are:

• Weddell seal

• Crabeater Seal

• Ross seal

• leopard seal

Various whale species also occur around and under the Antarctic pack ice. It has been estimated that Southern Ocean whales alone eat about 55 million tons of squid; this corresponds to about three quarters of the volume of fish caught by the world's fishing fleets. Blue whales, minke whales, humpback whales, killer whales and various other whale species share this habitat.

 

birds

penguins

There are 18 species of penguins in total, some of which are found only in Antarctica. The species found in Antarctica are listed here:

• emperor penguin

• adelie penguin

• chinstrap penguin

• Gentoo penguin

Only two species of penguins breed on the Antarctic pack ice: the emperor penguin and the Adelie penguin.

 

Birds capable of flying

However, birds breeding on the Antarctic continent also include 19 species of flying birds such as the royal albatross, snow petrel and silver petrel, both of which nest on mountains some hundred kilometers inland that jut out ice-free. Also found in Antarctica is the southern giant petrel, which is one of the natural enemies of emperor penguin colonies. In summer there are more than 100 million migratory birds that breed on the pack ice and the offshore islands.

 

Story

Long before the discovery of the continent of Antarctica in 1820, a vast southern continent was believed to exist to counterbalance the land masses of the northern hemisphere. This continent, called Terra australis, is depicted on numerous early modern world maps. Since some of these representations, for example the 1513 map of Piri Reis, the map of Orontius Finaeus of 1531, the map of Gerhard Mercator of 1569 or the map of Philippe Buache of 1754, show certain similarities with the actual position and shape of Antarctica , there are authors who suggest that Antarctica was discovered long before the official date of 1820. However, this is neither the only nor the most plausible possible interpretation, particularly for Piri Reis's map.

In fact, there is no evidence of human presence in Antarctica before the 19th century. However, voyages of discovery have already been undertaken in the southern polar region, for example the South Shetland Islands were probably discovered as early as 1599 by Dirk Gerritz or Gabriel de Castilla in 1603. James Cook crossed the Southern Ocean between 1772 and 1775, probably becoming the first man to cross the Antarctic Circle in 1773, but pack ice prevented him from seeing Antarctica himself.

 

Discovery and Pole Exploration

The first sighting of Antarctica cannot be pinned down to one event with absolute certainty: Russian Navy Captain Fabian von Bellingshausen, British Navy Captain Edward Bransfield, and US sealer Nathaniel Palmer all sighted Antarctica within days or weeks, probably was Bellingshausen on January 16th. / January 28, 1820greg. the first. The first landing was made just a year later by US seal hunter John Davis on February 7, 1821, when he sent some of his men ashore in a boat to look for seals.[20] In good weather conditions, the English navigator James Weddell was able to advance to latitude 74° 15′ south in the Weddell Sea, which was named after him. The French king then commissioned Jules Dumont d'Urville to break this record, but his 1837–1838 voyage was only successful on the second attempt when he sighted Adelie land.

After the Arctic magnetic pole was located in 1831, James Clark Ross set out for the Antarctic magnetic pole in 1839 with his ships HMS Erebus and HMS Terror. While searching for it, Ross was able to determine its approximate position, but could not reach it. In the process, he also charted the Ross Sea, a lake region later named after him.

But the actual conquest of Antarctica began in 1895 with the 6th International Geographical Congress, which took place at London's Imperial Institute. On August 3, that Congress passed a resolution stating, "that this Congress record its opinion that the exploration of the Antarctic regions is the greatest piece of geographical exploration still to be undertaken," and called on the world's scientists to to plan expeditions there.

A new era of Antarctic discovery began in 1928 with the expeditions of American Richard Evelyn Byrd and Australian Hubert Wilkins. Wilkins performed the world's first powered flight in Antarctica on November 16, 1928 and flew over the Antarctic Peninsula on December 20, 1928 with Carl Ben Eielson. On the second Wilkins-Hearst expedition, Wilkins and other pilots were able to complete several flights over the Antarctic mainland between December 1929 and January 1930. However, Byrd achieved greater success on his first of five Antarctic expeditions, when the aircraft Floyd Bennett, piloted by Bernt Balchen, reached the South Pole on November 29, 1929. On November 23, 1935, the American Lincoln Ellsworth and his pilot Herbert Hollick-Kenyon (1897-1975) started the first successful trans-Antarctic flight.

In his explorations, Byrd placed the main focus on research. During Operation Highjump, the largest Antarctic expedition in history, which took place from December 1946 to April 1947, Byrd brought 4,700 people, 13 ships and 23 aircraft to Little America IV base in McMurdo Sound and had more than 70,000 aerial photographs taken. Byrd's expeditions laid the basis for modern mapping and exploration of the continent.

In 1938, a German expedition headed by the experienced polar captain Alfred Ritscher planned a voyage to the South Pole. The catapult ship Schwabenland was selected as the ship, Lufthansa's floating aircraft base, from which 10-ton Dornier flying boats of the Wal type could take off with the help of steam catapults. Lufthansa had been using this revolutionary technology for airmail traffic with South America since 1934. The Schwabenland was made suitable for the Antarctic expedition in Hamburg shipyards in autumn 1938. After the conversion work on the Schwabenland (it had previously been used mainly in tropical waters), it left Hamburg on December 17, 1938 and reached the Antarctic on January 19, 1939. In the following weeks, almost 600,000 were flown on a total of 15 flights by the two flying boats Boreas and Passat km² area flown over and photographed. 11,000 pictures were taken. Almost 1/5 of the Antarctic area was documented for the first time.

The staff at the Antarctic stations are selected according to strict medical and psychological criteria, as the stations are usually isolated from the outside world for long periods of time. The scientists' medical and psychological observation offers unique opportunities to study, among other things, the influence of day/night rhythms, nutrition and psychological well-being of small groups under high stress.

 

astrophysics

In the course of the 20th century, the possibilities that Antarctica offered for astrophysical studies were recognized: In 1912, Frank Bickerton, a member of the Mawson expedition, accidentally discovered the first meteorite in Antarctica. A systematic search for meteorites has been carried out since 1969, since the Antarctic meteorites are very well preserved and show only slight signs of weathering. Meteoritic objects have been found at a few locations in Antarctica.

Detectors for cosmic rays have been in operation since the 1950s, and since the 1980s the site has been studied and used increasingly for infrared, submillimetre, radio and neutrino astronomy.

 

climatology

The ice cores obtained by glaciologists are an important source of information for climatologists, as conclusions can be drawn about the climate history of the earth from their composition and layer structure. These ice archives go back further into Earth's history than anywhere else on Earth. At the same time, they provide complementary information on the ice cores from the northern hemisphere, such as those from Greenland, since regional differences can be identified due to the large spatial distance in which the samples were taken.

 

meteorology

The Antarctic plays an important role for the weather in the southern hemisphere and, within the framework of one, also for the global climate, which is why extensive meteorological studies are carried out on the continent. These studies have been passed on to the neighboring countries since the 1950s, as they are of great importance for weather forecasts.

In the polar winter, one of the two terrestrial polar vortices forms over the South Pole, which is subject to the Antarctic Oscillation (AAO); their expression and thus possible weather effectiveness is described with the "AAO Index".

Aeronomic investigations of the higher layers of the earth's atmosphere, especially the stratosphere, gained importance in the late 20th century. The focus here is research on the ozone hole, which was first detected in 1985 over the South Pole.

 

politics

Far removed from world trade routes, inhospitable and hostile to life, Antarctica was unaffected by the colonization of the 19th and early 20th centuries. Even the states that assert classic territorial claims had to admit that actually enforcing such claims is simply unrealistic.

On the initiative of the Geophysical Year in 1957/58, a form of international cooperation was found that is just as unique as Antarctica itself exempt Antarctica from economic exploitation and military use. At the height of the Cold War, an international treaty was created that today occupies a key position in international environmental policy.

 

Antarctica in world politics

The Second World War occasionally reached as far as the (sub)Antarctic metropolitan area. In 1940, the German auxiliary cruisers Pinguin, Atlantis and Komet headed for the Kerguelen for supply purposes and repair work. The sailor Bernhard Herrmann had a fatal accident while repairing the Atlantis. His burial place is the southernmost German soldier's grave. The possibility of a German U-boat base on the Kerguelen prompted the Allies to mine some of the anchorages, keeping the Germans off the islands for the rest of the war. In mid-January 1941, the Pinguin captured two whale cookers, a supply ship and eleven fishing boats southwest of Bouvet Island. With Operation Tabarin in 1944, Great Britain reinforced its claim to parts of Antarctica.

Only once did hostilities erupt on the Antarctic continent itself over territorial claims: in 1952, Argentine soldiers shot at British researchers as they attempted to rebuild a destroyed research station. Argentina claimed the Antarctic Peninsula because that tongue of land is only about 900 miles (1480 km) from the southern tip of South America at its northern end.

After Amundsen and Scott, it was not until October 31, 1956 that a person was on the South Pole again, when the US Rear Admiral George J. Dufek landed there in an R4D Skytrain aircraft.

The Antarctic Treaty is an international agreement that stipulates that uninhabited Antarctica between latitude 60 and 90 degrees south is reserved for peaceful use only, particularly scientific research. The treaty was discussed by twelve signatory states at the Antarctic Conference in Washington in 1959 and came into force in 1961. It is of great political importance because it was the first treaty after the end of the Second World War that laid down the principles of peaceful coexistence between states with different social systems.

The Antarctic Treaty was signed on December 1, 1959 and came into effect on June 23, 1961.

 

Traffic

Traffic in the Antarctic is mainly based on the climatic conditions in order to keep the ecological footprint as small as possible.

On November 28, 1979, a McDonnell Douglas DC-10 on Air New Zealand Flight 901 crashed into Mount Erebus as a result of a navigation error. On November 13, 1998, a New York Air National Guard LC-130 Hercules aircraft on a resupply flight became stuck in a crevasse.

 

fishing

In the 1998/99 season, almost 120,000 tons were officially caught in the rich Antarctic fishing grounds, but an estimated five times as much due to illegal fishing. In 1998, eight illegal fishing trawlers were captured by the French and Australian navies.

In the 2009-10 fishing season, 202,000 tonnes of krill were caught in Antarctic waters, or four times the 2002-03 figure, according to the journal PNAS.

Krill fishing in Antarctica has now been largely phased out, with 85% of the krill industry operating in Antarctica having signed a pledge to ban fishing for krill in certain areas. There are also buffer zones, such as around penguin colonies.

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