Territorial claims in Antarctica
There are seven sovereign states who maintain de jure symbolic territorial claims in Antarctica: Argentina, Chile, New Zealand and the United Kingdom. These countries have tended to place their Antarctic scientific observation and study facilities within their respective claimed territories. According to Argentina and Chile, the Spanish Empire had claims on Antarctica; the capitulación granted to the conquistador Pedro Sánchez de la Hoz explicitly included all lands south of the Straits of Magellan. This grant established, according to Argentina and Chile, that an animus occupandi existed on the part of Spain in Antarctica. Spain's sovereignty claim over parts of Antarctica was, according to Chile and Argentina, internationally recognized with the Inter caetera bull of 1493 and the Treaty of Tordesillas of 1494. Argentina and Chile treat these treaties as legal international treaties mediated by the Catholic Church, at that time a recognized arbiter in such matters; each country has claim a sector of the Antarctic continent, more or less directly south of its national antarctic-facing lands.
The United Kingdom reasserted sovereignty over the Falkland Islands in the far South Atlantic in 1833 and maintained a continuous presence there. In 1908, the British government extended its territorial claim by declaring sovereignty over "South Georgia, the South Orkneys, the South Shetlands, the Sandwich Islands, Graham's Land, situated in the South Atlantic Ocean and on the Antarctic continent to the south of the 50th parallel of south latitude, lying between the 20th and the 80th degrees of west longitude". All these territories were administered as Falkland Islands Dependencies from Stanley by the Governor of the Falkland Islands; the motivation for this declaration lay in the need to regulate and tax the whaling industry effectively. Commercial operators would hunt whales in areas outside the official boundaries of the Falkland Islands and its dependencies, there was a need to close this loophole. In 1917, the wording of the claim was modified, so as to unambiguously include all the territory in the sector stretching to the South Pole.
The new claim covered "all islands and territories whatsoever between the 20th degree of west longitude and the 50th degree of west longitude which are situated south of the 50th parallel of south latitude. It was the ambition of Leopold Amery Under-Secretary of State for the Colonies, that Britain incorporate the entire continent into the Empire. In a memorandum to the governors-general for Australia and New Zealand, he wrote that'with the exception of Chile and Argentina and some barren islands belonging to France... it is desirable that the whole of the Antarctic should be included in the British Empire.' The first step was taken on 30 July 1923, when the British government passed an Order in Council under the British Settlements Act 1887, defining the new borders for the Ross Dependency—"that part of His Majesty's Dominions in the Antarctic Seas, which comprises all the islands and territories between the 160th degree of East Longitude and the 150th degree of West Longitude which are situated south of the 60th degree of South Latitude shall be named the Ross Dependency."
The Order in Council went on to appoint the Governor-General and Commander-in Chief of New Zealand as the Governor of the territory. In 1930, the United Kingdom claimed Enderby Land. In 1933, a British imperial order transferred territory south of 60° S and between meridians 160° E and 45° E to Australia as the Australian Antarctic Territory. Following the passing of the Statute of Westminster in 1931, the government of the United Kingdom relinquished all control over the government of New Zealand and Australia; this however had no bearing on the obligations of the governors-general of both countries in their capacity as Governors of the Antarctic territories. The basis for the claim to Adélie Land by France depended on the discovery of the coastline in 1840 by the French explorer Jules Dumont d'Urville, who named it after his wife, Adèle.. He erected the French flag and took possession of the land for France, on January 21st, 1840 at 5:30 PM; the British decided to recognize this claim, the border between Adélie Land and the Australian Antarctic Territory was fixed definitively in 1938.
These developments concerned Norwegian whaling interests, which wished to avoid British taxation of whaling stations in the Antarctic and felt concerns that they would be commercially excluded from the continent. The whale-ship owner Lars Christensen financed several expeditions to the Antarctic with the view to claiming land for Norway and to establishing stations on Norwegian territory to gain better privileges; the first expedition, led by Nils Larsen and Ola Olstad, landed on Peter I Island in 1929 and claimed the island for Norway. On 6 March 1931 a Norwegian royal proclamation declared the island under Norwegian sovereignty and on 23 March 1933 the island was declared a dependency; the 1929 expedition led by Hjalmar Riiser-Larsen and Finn Lützow-Holm named t
International Geophysical Year
The International Geophysical Year was an international scientific project that lasted from July 1, 1957, to December 31, 1958. It marked the end of a long period during the Cold War when scientific interchange between East and West had been interrupted. Sixty-seven countries participated in IGY projects, although one notable exception was the mainland People's Republic of China, protesting against the participation of the Republic of China. East and West agreed to nominate the Belgian Marcel Nicolet as secretary general of the associated international organization; the IGY encompassed eleven Earth sciences: aurora and airglow, cosmic rays, gravity, ionospheric physics and latitude determinations, oceanography and solar activity. The timing of the IGY was suited for studying some of these phenomena, since it covered the peak of solar cycle 19. Both the Soviet Union and the U. S. launched artificial satellites for this event. Other significant achievements of the IGY included the discovery of the Van Allen radiation belts by Explorer 1 and the defining of mid-ocean submarine ridges, an important confirmation of plate-tectonic theory.
Detected was the rare occurrence of hard solar corpuscular radiation that could be dangerous for manned space flight. The origin of the International Geophysical Year can be traced to the International Polar Years held in 1882–1883 in 1932–1933 and the last one was in March 2007 to March 2009. On 5 April 1950, several top scientists, met in James Van Allen's living room and suggested that the time was ripe to have a worldwide Geophysical Year instead of a Polar Year considering recent advances in rocketry and computing. Berkner and Chapman proposed to the International Council of Scientific Unions that an International Geophysical Year be planned for 1957–58, coinciding with an approaching period of maximum solar activity. In 1952, the IGY was announced. Joseph Stalin's death in 1953 opened the way for international collaboration with the Soviet Union. On 29 July 1955, James C. Hagerty, president Dwight D. Eisenhower's press secretary, announced that the United States intended to launch "small Earth circling satellites" between 1 July 1957 and 31 December 1958 as part of the United States contribution to the International Geophysical Year.
Project Vanguard would be managed by the Naval Research Laboratory and to be based on developing sounding rockets, which had the advantage that they were used for non-military scientific experiments. Four days at the Sixth Congress of International Astronautical Federation in Copenhagen, scientist Leonid I. Sedov spoke to international reporters at the Soviet embassy, announced his country's intention to launch a satellite as well, in the "near future". To the surprise of many, the USSR launched Sputnik 1 as the first artificial Earth satellite on October 4, 1957. After several failed Vanguard launches, Wernher von Braun and his team convinced President Dwight D. Eisenhower to use one of their US Army missiles for the Explorer program. On November 8, 1957, the US Secretary of Defense instructed the US Army to use a modified Jupiter-C rocket to launch a satellite; the US achieved this goal only four months with Explorer 1, on February 1, 1958, but after Sputnik 2 in November 3, 1957, making Explorer 1 the third artificial Earth satellite.
Vanguard 1 became the fourth, launched on March 17, 1958. The Soviet victory in the "Space Race" would be followed by considerable political consequences, one of, the creation of the US space agency NASA on July 29, 1958; the British-American survey of the Atlantic, carried out between September 1954 and July 1959, that discovered full length of the mid-Atlantic ridges, was a major discovery during the IGY. Although the 1932 Polar Year accomplished many of its goals, it fell short on others because of the advance of World War II. In fact, because of the war, much of the data collected and scientific analyses completed during the 1932 Polar Year were lost forever, something, troubling to the IGY organizing committee; the committee resolved that "all observational data shall be available to scientists and scientific institutions in all countries." They felt that without the free exchange of data across international borders, there would be no point in having an IGY. In April 1957, just three months before the IGY began, scientists representing the various disciplines of the IGY established the World Data Center system.
The United States hosted World Data Center "A" and the Soviet Union hosted World Data Center "B." World Data Center "C" was subdivided among countries in Western Europe and Japan. Today, NOAA hosts seven of the fifteen World Data Centers in the United States; each World Data Center would archive a complete set of IGY data to deter losses prevalent during the International Polar Year of 1932. Each World Data Center was equipped to handle many different data formats, including computer punch cards and tape—the original computer media. In addition, each host country agreed to abide by the organizing committee’s resolution that there should be a free and open exchange of data among nations. ICSU-WDS goals are to preserve quality assured scientific data and information, to facilitate open access, promote the adoption of standards. ICSU World Data System created in 2008 superseded the World Data Centeres and Fed
France Antarctique
France Antarctique was a French colony south of the Equator, in Rio de Janeiro, which existed between 1555 and 1567, had control over the coast from Rio de Janeiro to Cabo Frio. The colony became a haven for the Huguenots, was destroyed by the Portuguese in 1567. Europeans first arrived in Brazil in April 1500, when a fleet commanded by Pedro Álvares Cabral on behalf of the Portuguese crown arrived in present-day Porto Seguro, Bahia. Except for Salvador and São Vicente, the territory still remained unexplored half a century later. Early expeditions of French Norman sailors to the New World have been suggested: Jean Cousin has been said to have discovered the New World in 1488, four years before Christopher Columbus, when he landed in Brazil around the mouth of the Amazon, but this remains unproven, his travels were succeeded by that of Binot Paulmier de Gonneville in 1504 onboard L'Espoir, properly recorded and brought back a Native American person named Essomericq. Gonneville affirmed that when he visited Brazil, French traders from Saint-Malo and Dieppe had been trading there for several years.
France continued to trade with Portugal loading Brazilwood, for its use as a red dyes for textiles. In 1550, in the royal entry for Henry II of France, at Rouen, about fifty men depicted naked Indians and a battle between the Tupinamba allies of the French, the Tabajaras Indians. On November 1, 1555, French vice-admiral Nicolas Durand de Villegaignon, a Catholic knight of the Order of Malta, who would help the Huguenots to find a refuge against persecution, led a small fleet of two ships and 600 soldiers and colonists, took possession of the small island of Serigipe in the Guanabara Bay, in front of present-day Rio de Janeiro, where they built a fort named Fort Coligny; the fort was named in honor of Gaspard de Coligny, an admiral who supported the expedition and would use the colony in order to protect his Reformed co-religionists. To the still undeveloped mainland village, Villegaignon gave the name of Henriville, in honour of Henry II, the King of France, who knew of and approved the expedition, had provided the fleet for the trip.
Villegaignon secured his position by making an alliance with the Tamoio and Tupinambá Indians of the region, who were fighting the Portuguese. Unchallenged by the Portuguese, who took little notice of his landing, Villegaignon endeavoured to expand the colony by calling for more colonists in 1556, he sent one of his ships, the Grande Roberge, to Honfleur, entrusted with letters to King Henry II, Gaspard de Coligny and according to some accounts, the Protestant leader John Calvin. After one ship was sent to France to ask for additional support, three ships were financed and prepared by the king of France and put under the command of Sieur De Bois le Comte, a nephew of Villegaignon, they were joined by 14 Calvinists from Geneva, led by Philippe de Corguilleray, including theologians Pierre Richier and Guillaume Chartrier. The new colonists, numbering around 300, included 5 young women to be wed, 10 boys to be trained as translators, as well as 14 Calvinists sent by Calvin, Jean de Léry, who would write an account of the colony.
They arrived in March 1557. The relief fleet was composed of: The Petite Roberge, with 80 soldiers and sailors was led by Vice Admiral Sieur De Bois le Comte; the Grande Roberge, with about 120 on board, captained by Sieur de Sainte-Marie dit l'Espine. The Rosée, with about 90 people, led by Captain Rosée. Doctrinal disputes arose between Villegaignon and the Calvinists in relation to the Eucharist, in October 1557 the Calvinists were banished from Coligny island as a result, they settled among the Tupinamba until January 1558, when some of them managed to return to France by ship together with Jean de Léry, five others chose to return to Coligny island where three of them were drowned by Villegaignon for refusing to recant. In 1560 Mem de Sá, the new Governor-General of Brazil, received from the Portuguese government the command to expel the French. With a fleet of 26 warships and 2,000 soldiers, on 15 March 1560, he attacked and destroyed Fort Coligny within three days, but was unable to drive off their inhabitants and defenders, because they escaped to the mainland with the help of the Native Brazilians, where they continued to live and to work.
Admiral Villegaignon had returned to France in 1558, disgusted with the religious tension that existed between French Protestants and Catholics, who had come with the second group. Urged by two influential Jesuit priests who had come to Brazil with Mem de Sá, named José de Anchieta and Manuel da Nóbrega, who had played a big role in pacifying the Tamoios, Mem de Sá ordered his nephew, Estácio de Sá to assemble a new attack force. Estácio de Sá founded the city of Rio de Janeiro on March 1, 1565, fought the Frenchmen for two more years. Helped by a military reinforcement sent by his uncle, on January 20, 1567, he imposed final defeat on the French forces and decisively expelled them from Brazil, but died a month from wounds inflicted in the battle. Coligny's and Villegaignon's dream had lasted a mere 12 years. In response to the two attempts of France to conquer territory in Brazil, between 1612 and 1615, the Portuguese crown decided to expand its colonization efforts in Brazil. Other projects were made for the occupation of parts of Brazil in 1579, following the death of Sebastia
Crozet Islands
The Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Antarctic Lands; the Crozet Islands were discovered on 24 January 1772 by the expedition of French explorer Marc-Joseph Marion du Fresne, aboard Le Mascarin. His second-in-command Jules Crozet landed on Île de la Possession, claiming the archipelago for France; the expedition continued east and landed at New Zealand, where Captain Marion and much of his crew were killed and cannibalized by Maori. Crozet survived the disaster, led the survivors back to their base at Mauritius. In 1776 Crozet met James Cook at Cape Town, at the onset of Cook's third voyage. Crozet shared the charts of his ill-fated expedition, as Cook sailed eastward he stopped at the islands, naming the western group Marion and the eastern group Crozet. In the following years, sealers visiting the islands referred to both the eastern and western groups as the Crozet Islands, Marion Island became the name of the larger of the two Prince Edward Islands, which were discovered by Captain Marion on the same expedition.
In the early 19th century, the islands were visited by sealers, to the extent that the seals had been nearly exterminated by 1835. Between 1804 and 1911, 153 vessels visited the island for seals, seven of which wrecked on the coast. Subsequently, whaling was the main activity around the islands by the whalers from Massachusetts. In 1841 there were a dozen whaleships around the islands. Within a couple of years this had increased to twenty from the United States alone; such exploitation was short-lived, the islands were visited for the rest of the century. Shipwrecks occurred at the Crozet Islands; the British sealer, Princess of Wales, sank in 1821, the survivors spent two years on the islands. The Strathmore was wrecked in 1875. In 1887, the French Tamaris was wrecked and her crew stranded on Île des Cochons, they tied a note to the leg of an albatross, found seven months in Fremantle, but the crew was never recovered. Because shipwrecks around the islands were so common, for some time the Royal Navy dispatched a ship every few years to look for stranded survivors.
The steamship Australasian checked for survivors en route to Australia. Between 1924 and 1955, France administered the islands as a dependency of Madagascar. Crozet Islands became part of the French Southern Territories in 1955. In 1938, the Crozet Islands were declared a nature reserve. In 1961, a first research station was set up, but it was not until 1963 that the permanent station Alfred Faure opened at Port Alfred on Île de la Possession; the station is staffed by 18 to 30 people and does meteorological and geological research, maintains a seismograph and a geomagnetic observatory. The Comprehensive Nuclear Test Ban Treaty Organization has listening equipment on the island after the CTBTO disclosed that two of its stations, the other being on Ascension Island, detected what is believed to be an underwater, non-nuclear explosion off the coast of Argentina and believed to be a fatal accident of the ARA San Juan submarine in 2017; the islands lie on the Antarctic Plate between the Kerguelen hotspot and Madagascar and southern Africa.
The oldest East Island formed 9 million years ago from a hotspot which has continued forming islands to the west until, the present. Despite this young age, no volcanic activity has been observed to date on any of the islands. Not including minor islets or rock reefs etc. the Crozet group consists of six islands. From west to east: Group of two major islands and about 20 pinnacle rocks; the Eastern and Western Groups are 94.5 kilometres apart The Crozet Islands are uninhabited, except for the research station Alfred Faure on the East side of Île de la Possession, continuously manned since 1963. Previous scientific stations included La Petite Manchotière; the Crozet islands have a maritime-influenced tundra climate. Monthly temperatures average around 2.9 7.9 °C in winter and summer respectively. Precipitation is high, with over 2,000 mm per year, it rains on average 300 days a year, winds exceeding 100 km/h occur on 100 days a year. The temperatures may rise to 18 °C in summer and go below −5 °C in winter.
The islands are part of the Southern Indian Ocean Islands tundra ecoregion that includes several subantarctic islands. In this cold climate plant life is limited to grasses and lichens, while the main animals are insects along with large populations of seabirds and penguins; the Crozet Islands are home to four species of penguins. Most abundant are the macaroni penguin, of which some 2 million pairs breed on the islands, the king penguin, home to 700,000 breeding pairs; the eastern rockhopper penguin can be found, there is a small colony of gentoo penguins. There is an endemic subspecies of the duck Eaton's pintail. Other birds include black-faced sheathbills and albatross, including the wandering albatross. Mammals living on the Crozet Islands include fur seals, southern elephant seals. Killer whales have been observed preying upon the seals; the transient killer whales of the Crozet Islands are famous for intentionally beaching themselves while activ
French Southern and Antarctic Lands
The French Southern and Antarctic Lands is an overseas territory of France. It consists of: Kerguelen Islands, a group of volcanic islands in the southern Indian Ocean, southeast of Africa equidistant between Africa and Australia; the territory is sometimes referred to as the French Southern Lands or French Southern Territories to emphasize non-recognition of French sovereignty over Adélie Land as part of the Antarctic Treaty system. The territory has no permanent civilian population; those resident consist of visiting military personnel, scientific researchers and support staff. The French Southern and Antarctic Lands have formed a territoire d'outre-mer of France since 1955, they were administered from Paris by an administrateur supérieur assisted by a secretary-general. The territory is divided into five districts: a According to new law 2007-224 of February 21, 2007, the Scattered Islands constitute the TAAF's fifth district; the TAAF website does not mention their population. The data are not included in the totals.b.
The headquarters of the district chief lies beyond the TAAF, in Saint-Pierre on Réunion Island.c The Territory's principal station is Martin-de-Viviès on Île Amsterdam. The capital and headquarters of the Territorial administrator lies beyond the TAAF, in Saint-Pierre on Réunion Island; each district is headed by a district chief. Because there is no permanent population, there is no elected assembly, nor does the territory send representatives to the national parliament; the territory includes Amsterdam Island, Saint-Paul Island, Crozet Islands, the Kerguelen Islands in the southern Indian Ocean near 43°S, 67°E, along with Adélie Land, the sector of Antarctica claimed by France, named by the French explorer Jules Dumont d'Urville after his wife. Adélie Land and the islands, totaling 7,781 km2, have no indigenous inhabitants, though in 1997 there were about 100 researchers whose numbers varied from winter to summer. Amsterdam Island and Saint-Paul Island are extinct volcanoes and have been delineated as the Amsterdam and Saint-Paul Islands temperate grasslands ecoregion.
The highest point in the territory is Mont Ross on Kerguelen Island at 1,850 m. There are few airstrips on the islands, only existing on islands with weather stations, the 1,232 km of coastline have no ports or harbors, only offshore anchorages; the islands in the Indian Ocean are supplied by the special ship Marion Dufresne sailing out of Le Port in Réunion Island. Terre Adélie is supplied by Astrolabe sailing out of Hobart in Tasmania. However, the territory has a merchant marine fleet totaling 2,892,911 GRT/5,165,713 tonnes deadweight, including seven bulk carriers, five cargo ships, ten chemical tankers, nine container ships, six liquefied gas carriers, 24 petroleum tankers, one refrigerated cargo ship, ten roll-on-roll-off carriers; this fleet is maintained as a subset of the French register that allows French-owned ships to operate under more liberal taxation and manning regulations than permissible under the main French register. This register, however, is to vanish; the territory's natural resources are limited to fish and crustaceans.
Economic activity is limited to servicing meteorological and geophysical research stations and French and other fishing fleets. The main fish resources are Patagonian spiny lobster. Both are poached by foreign fleets; such arrests can result in heavy fines and/or the seizure of the ship. France sold licenses to foreign fisheries to fish the Patagonian toothfish; the territory takes in revenues of about €16 million a year. The French Southern Territories have been given the following country codes: FS and TF. France Outline of France French overseas departments and territories Administrative divisions of France Islands controlled by France in the Indian and Pacific oceans French colonial empire List of French possessions and colonies Wikimedia Atlas of the French Southern and Antarctic Lands Official website French Southern and Antarctic Lands – Official French website "French Southern and Antarctic Lands"; the World Factbook. Central Intelligence Agency. French Southern Territories at Curlie Southern & Antarctic Territories Crozet Archipelago Kerguelen Archipelago Terre Adélie
Wilkes Land
Wilkes Land is a large district of land in eastern Antarctica, formally claimed by Australia as part of the Australian Antarctic Territory, though the validity of this claim has been placed for the period of the operation of the Antarctic Treaty, to which Australia is a signatory. It fronts on the southern Indian Ocean between Queen Mary Coast and Adelie Land, extending from Cape Hordern in 100°31' E to Pourquoi Pas Point, in 136°11' E; the region extends as a sector about 2600 km towards the South Pole, with an estimated land area of 2,600,000 km² glaciated. It is further subdivided in the following coastal areas which can be thought of as sectors extending to the South Pole: Knox Land: 100°31' E to 109°16' E Budd Land: 109°16' E to 115°33' E Sabrina Land: 115°33' E to 122°05' E Banzare Land: 122°05' E to 130°10' E Clarie Land: 130°10' E to 136°11' EIn a wider sense, Wilkes Land extends further East to Point Alden in 142°02' E, thereby including Adélie Land, claimed by France. Wilkes Land is named after Lieutenant Charles Wilkes, the American explorer who commanded the 1838–42 United States Exploring Expedition.
The naming is in recognition of Wilkes' discovery of the continental margin over a distance of 2,400 km of coast, thus providing substantial proof that Antarctica is a continent. This definition of extent excludes the area east of 142°02' E, George V Land, sighted by Wilkes but has been shown by expeditions to be further south than the positions assigned by him. In 2006 a team of researchers led by Ralph von Frese and Laramie Potts used gravity measurements by NASA's GRACE satellites to discover the 300-mile-wide Wilkes Land crater, which formed about 250 million years ago. Wilkes Land is featured prominently in the 1998 film The X-Files. Fox Mulder journeys to Antarctica to save his partner Dana Scully, being held there against her will. In the process, they discover a huge secret lab under the surface run by the Cigarette-Smoking Man. Adélie Valley
Antarctic ice sheet
The Antarctic ice sheet is one of the two polar ice caps of the Earth. It is the largest single mass of ice on Earth, it covers an area of 14 million square kilometres and contains 26.5 million cubic kilometres of ice. A cubic kilometer of ice weighs one metric gigaton, meaning that the ice sheet weighs 26,500,000 gigatons. 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet, an amount equivalent to about 58 m of sea-level rise. In East Antarctica, the ice sheet rests on a major land mass, while in West Antarctica the bed can extend to more than 2,500 m below sea level. In contrast to the melting of the Arctic sea ice, sea ice around Antarctica was expanding as of 2013. Satallite measurements by NASA indicate a still increasing sheet thickness above the continent, outweighing the losses at the edge; the reasons for this are not understood, but suggestions include the climatic effects on ocean and atmospheric circulation of the ozone hole, and/or cooler ocean surface temperatures as the warming deep waters melt the ice shelves.
The icing of Antarctica began in the middle Eocene about 45.5 million years ago and escalated during the Eocene–Oligocene extinction event about 34 million years ago. CO2 levels were about 760 ppm and had been decreasing from earlier levels in the thousands of ppm. Carbon dioxide decrease, with a tipping point of 600 ppm, was the primary agent forcing Antarctic glaciation; the glaciation was favored by an interval when the Earth's orbit favored cool summers but oxygen isotope ratio cycle marker changes were too large to be explained by Antarctic ice-sheet growth alone indicating an ice age of some size. The opening of the Drake Passage may have played a role as well though models of the changes suggest declining CO2 levels to have been more important; the Western Antarctic ice sheet declined somewhat during the warm early Pliocene epoch 5 to 3 million years ago. But there was no significant decline in the land-based Eastern Antarctic ice sheet. According to a 2009 study, the continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05 °C/decade since 1957.
West Antarctica has warmed by more than 0.1 °C/decade in the last 50 years, this warming is strongest in winter and spring. Although this is offset by fall cooling in East Antarctica, this effect is restricted to the 1980s and 1990s. Ice enters the sheet through precipitation as snow; this snow is compacted to form glacier ice which moves under gravity towards the coast. Most of it is carried to the coast by fast moving ice streams; the ice passes into the ocean forming vast floating ice shelves. These shelves melt or calve off to give icebergs that melt. If the transfer of the ice from the land to the sea is balanced by snow falling back on the land there will be no net contribution to global sea levels; the general trend shows that a warming climate in the southern hemisphere would transport more moisture to Antarctica, causing the interior ice sheets to grow, while calving events along the coast will increase, causing these areas to shrink. A 2006 paper derived from satellite data, measuring changes in the gravity of the ice mass, suggests that the total amount of ice in Antarctica has begun decreasing in the past few years.
A 2008 study compared the ice leaving the ice sheet, by measuring the ice velocity and thickness along the coast, to the amount of snow accumulation over the continent. This found that the East Antarctic Ice Sheet was in balance but the West Antarctic Ice Sheet was losing mass; this was due to acceleration of ice streams such as Pine Island Glacier. These results agree with the gravity changes. An estimate published in November 2012 and based on the GRACE data as well as on an improved glacial isostatic adjustment model discussed systematic uncertainty in the estimates, by studying 26 separate regions, estimated an average yearly mass loss of 69 ± 18 Gt/y from 2002 to 2010; the mass loss was geographically uneven occurring along the Amundsen Sea coast, while the West Antarctic Ice Sheet mass was constant and the East Antarctic Ice Sheet gained in mass. Antarctic sea ice anomalies have followed the pattern of warming, with the greatest declines occurring off the coast of West Antarctica. East Antarctica sea ice has been increasing since 1978, though not at a statistically significant rate.
The atmospheric warming has been directly linked to the mass losses in West Antarctica of the first decade of the twenty-first century. This mass loss is more to be due to increased melting of the ice shelves because of changes in ocean circulation patterns. Melting of the ice shelves in turn causes; the melting and disappearance of the floating ice shelves will only have a small effect on sea level, due to salinity differences. The most important consequence of their increased melting is the speed up of the ice streams on land which are buttressed by these ice shelves. A group of scientists with the University of California updated previous results ranging from 1979 to 2017, which improved time series for more accurate results, their article, published January 2019, covered four decades of information in Antarctica, revealing the total mass loss which increased per decade. 40 ± 9 Gt/y from 1979 to 1990, 50 ± 14 Gt/y from 1989 to 2000, 166 ±18 Gt/y from 1999 to 2009 and 252 ±26 Gt/y from 2009 to 2017.
The majority of mass loss
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