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88-550: Moscow University Ice Shelf ( 67°S 121°E  /  67°S 121°E  / -67; 121 ) is a narrow ice shelf , about 120 nautical miles (220 km) long, which fringes the Sabrina Coast of Antarctica between Totten Glacier and Paulding Bay . Dalton Iceberg Tongue extends north from the eastern part of the shelf. The feature was partly delineated from aerial photographs taken by U.S. Navy Operation Highjump in 1946–47, and further photographed and mapped by

176-458: A Northwest Passage to "the Western and Southern Ocean of America ". Authors using "Southern Ocean" to name the waters encircling the unknown southern polar regions used varying limits. James Cook 's account of his second voyage implies New Caledonia borders it. Peacock's 1795 Geographical Dictionary said it lay "to the southward of America and Africa"; John Payne in 1796 used 40 degrees as

264-415: A "hotspot of global warming". It broke over a period of three weeks or less, with a factor in this fast break-up being the powerful effects of water; ponds of meltwater formed on the surface during the near 24 hours of daylight in the summertime, flowed down into cracks and, acting like a multitude of wedges, levered the shelf apart. Other likely factors in the break-up were the higher ocean temperatures and

352-643: A captain in the Russian Imperial Navy ; Edward Bransfield , a captain in the Royal Navy ; and Nathaniel Palmer , an American sailor out of Stonington, Connecticut . It is certain that the expedition, led by von Bellingshausen and Lazarev on the ships Vostok and Mirny , reached a point within 32 km (20 mi) from Princess Martha Coast and recorded the sight of an ice shelf at 69°21′28″S 2°14′50″W  /  69.35778°S 2.24722°W  / -69.35778; -2.24722 that became known as

440-515: A huge ice island in 2017. From 31 January 2002 to March 2002 the Larsen B sector partially collapsed and parts broke up, 3,250 km (1,250 sq mi) of ice 220 m (720 ft) thick, an area comparable to the US state of Rhode Island . In 2015, a study concluded that the remaining Larsen B ice-shelf would disintegrate by 2020, based on observations of faster flow and rapid thinning of glaciers in

528-458: A land in 50° S which he called South France, and believed to be the central mass of the southern continent. He was sent out again to complete the exploration of the new land, and found it to be only an inhospitable island which he renamed the Isle of Desolation, but which was ultimately named after him . The obsession of the undiscovered continent culminated in the brain of Alexander Dalrymple ,

616-594: A large crack in the Ward Hunt shelf had begun to form, and in 2003 it was announced that the ice sheet had split completely in two in 2002, releasing a huge pool of freshwater from the largest epishelf lake in the Northern Hemisphere, located in Disraeli Fjord. In April 2008, scientists discovered that the shelf fractured into dozens of deep, multi-faceted cracks. On August 13, 2005, The Ayles Ice Shelf , which

704-523: A note in the publication read: The Antarctic or Southern Ocean has been omitted from this publication as the majority of opinions received since the issue of the 2nd Edition in 1937 are to the effect that there exists no real justification for applying the term Ocean to this body of water, the northern limits of which are difficult to lay down owing to their seasonal change. The limits of the Atlantic, Pacific and Indian Oceans have therefore been extended South to

792-536: A slow melt rate, in contrast to the undefended western portion. According to the American Geophysical Union in a 2021 study, the Thwaites Eastern Ice Shelf (TEIS) buttresses one-third of Thwaites glacier . Removal of the shelf has the potential to increase the contribution of Thwaites glacier to sea level rise by up to 25%. As of 2021 , the ice shelf appears to be losing its grip on

880-454: A submarine shoal that acts as a pinning point and the shear margin that separates the Thwaites Eastern Ice Shelf from the Thwaites glacier Tongue has extended, further weakening the ice shelf connection to the pinning point. A sequence of Sentinel-1 radar imagery shows that parallel wing and comb cracks have recently formed rifts at high angles to the main shear margin and are propagating into

968-734: Is a stub . You can help Misplaced Pages by expanding it . Ice shelf Ice shelves are found in Antarctica and the Arctic ( Greenland , Northern Canada , and the Russian Arctic ), and can range in thickness from about 100–1,000 m (330–3,280 ft). The world's largest ice shelves are the Ross Ice Shelf and the Filchner-Ronne Ice Shelf in Antarctica. The movement of ice shelves

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1056-516: Is about 1028 kg/m and that of glacial ice from about 850 kg/m to well below 920 kg/m , the limit for very cold ice without bubbles. The height of the shelf above the sea can be even larger, if there is much less dense firn and snow above the glacier ice. A large portion of the Antarctic coastline has ice shelves attached. Their aggregate area is over 1,550,000 square kilometers (600,000 square miles). It has been found that of all

1144-604: Is one of the biggest ice shelves in West Antarctica , though it is highly unstable and disintegrating rapidly. Since the 1980s, the Thwaites Glacier , nicknamed the "Doomsday glacier", has had a net loss of over 600 billion tons of ice, though pinning of the Thwaites Ice Shelf has served to slow the process. The Thwaites Ice Shelf has acted like a dam for the eastern portion of glacier, bracing it and allowing for

1232-423: Is principally driven by gravity -induced pressure from the grounded ice. That flow continually moves ice from the grounding line to the seaward front of the shelf. Typically, a shelf front will extend forward for years or decades between major calving events (calving is the sudden release and breaking away of a mass of ice from a glacier , iceberg , ice front , ice shelf, or crevasse ). Snow accumulation on

1320-575: The Antarctic Ocean , comprises the southernmost waters of the world ocean , generally taken to be south of 60° S latitude and encircling Antarctica . With a size of 21,960,000 km (8,480,000 sq mi), it is the second-smallest of the five principal oceanic divisions, smaller than the Pacific , Atlantic and Indian oceans, and larger than the Arctic Ocean . The maximum depth of

1408-618: The Australian National Antarctic Research Expeditions and the Soviet Antarctic Expedition in 1958. It was named by the Soviet expedition after Moscow University . [REDACTED]  This article incorporates public domain material from "Moscow University Ice Shelf" . Geographic Names Information System . United States Geological Survey . This Wilkes Land location article

1496-516: The Fimbul Ice Shelf . On 30 January 1820, Bransfield sighted Trinity Peninsula , the northernmost point of the Antarctic mainland, while Palmer sighted the mainland in the area south of Trinity Peninsula in November 1820. Von Bellingshausen's expedition also discovered Peter I Island and Alexander I Island , the first islands to be discovered south of the circle. In December 1839, as part of

1584-584: The Karpinsky Ice Cap to the south and the Rusanov Ice Cap to the north. In 2012 it ceased to exist. In the last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt, calving , and complete disintegration of some shelves. Well studied examples include disruptions of the Thwaites Ice Shelf , Larsen Ice Shelf , Filchner–Ronne Ice Shelf (all three in

1672-634: The Markham Ice Shelf broke up in 2008. The remaining ice shelves have also lost a significant amount of their area over time, with the Milne Ice Shelf being the last to be affected, with it breaking off in August 2020. The Matusevich Ice Shelf was a 222 square kilometers (86 square miles) ice shelf located in Severnaya Zemlya being fed by some of the largest ice caps on October Revolution Island ,

1760-609: The Strait of Magellan in 1520, assumed that the islands of Tierra del Fuego to the south were an extension of this unknown southern land. In 1564, Abraham Ortelius published his first map, Typus Orbis Terrarum , an eight-leaved wall map of the world, on which he identified the Regio Patalis with Locach as a northward extension of the Terra Australis , reaching as far as New Guinea . European geographers continued to connect

1848-575: The Thwaites Ice Shelf , Larsen Ice Shelf , Filchner–Ronne Ice Shelf (all three in the Antarctic) and the disruption of the Ellesmere Ice Shelf in the Arctic. An ice shelf is "a floating slab of ice originating from land of considerable thickness extending from the coast (usually of great horizontal extent with a very gently sloping surface), resulting from the flow of ice sheets , initially formed by

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1936-672: The United States Exploring Expedition of 1838–42 conducted by the United States Navy (sometimes called "the Wilkes Expedition"), an expedition sailed from Sydney, Australia, on the sloops-of-war USS  Vincennes and USS  Peacock , the brig USS  Porpoise , the full-rigged ship Relief , and two schooners Sea Gull and USS  Flying Fish . They sailed into the Antarctic Ocean, as it

2024-716: The parallel 60° south latitude was discovered by the Englishman William Smith , who sighted Livingston Island on 19 February 1819. A few months later Smith returned to explore the other islands of the South Shetlands archipelago, landed on King George Island , and claimed the new territories for Britain. In the meantime, the Spanish Navy ship San Telmo sank in September 1819 when trying to cross Cape Horn. Parts of her wreckage were found months later by sealers on

2112-399: The "South Land" – described by a half legendary " sieur de Gonneyville " – resulted in the discovery of Bouvet Island in 54°10′ S, and in the navigation of 48° of longitude of ice-cumbered sea nearly in 55° S in 1730. In 1771, Yves Joseph Kerguelen sailed from France with instructions to proceed south from Mauritius in search of "a very large continent". He lighted upon

2200-597: The 16th and the early part of the 17th centuries. The Spaniard Gabriel de Castilla , who claimed having sighted "snow-covered mountains" beyond the 64° S in 1603, is recognized as the first explorer that discovered the continent of Antarctica, although he was ignored in his time. In 1606, Pedro Fernández de Quirós took possession for the king of Spain all of the lands he had discovered in Australia del Espiritu Santo (the New Hebrides ) and those he would discover "even to

2288-511: The 2002 edition the limits of oceans explicitly excluded the seas lying within each of them. The Great Australian Bight was unnamed in the 1928 edition, and delineated as shown in the figure above in the 1937 edition. It therefore encompassed former Southern Ocean waters—as designated in 1928—but was technically not inside any of the three adjacent oceans by 1937. In the 2002 draft edition, the IHO have designated "seas" as subdivisions within "oceans", so

2376-533: The Antarctic Circle, or knew it, if they did. In a voyage from 1822 to 1824, James Weddell commanded the 160-ton brig Jane , accompanied by his second ship Beaufoy captained by Matthew Brisbane. Together they sailed to the South Orkneys where sealing proved disappointing. They turned south in the hope of finding a better sealing ground. The season was unusually mild and tranquil, and on 20 February 1823

2464-544: The Antarctic Continent. Hydrographic Offices who issue separate publications dealing with this area are therefore left to decide their own northern limits (Great Britain uses Latitude of 55 South.) Instead, in the IHO 1953 publication, the Atlantic, Indian and Pacific Oceans were extended southward, the Indian and Pacific Oceans (which had not previously touched pre 1953, as per the first and second editions) now abutted at

2552-477: The Antarctic mix with warmer Subantarctic waters, or not defined at all, with its waters instead treated as the southern limits of the Pacific, Atlantic, and Indian oceans. The International Hydrographic Organization (IHO) finally settled the debate after the full importance of Southern Ocean overturning circulation had been ascertained, and the term Southern Ocean now defines the body of water which lies south of

2640-488: The Antarctic) and the disruption of the Ellesmere Ice Shelf in the Arctic. The effects of climate change are visible in the changes to the cryosphere , such as reduction in sea ice and ice sheets , and disruption of ice shelves. Thwaites Ice Shelf (), is an Antarctic ice shelf in the Amundsen Sea . It was named by ACAN after Fredrik T. Thwaites, a glacial geologist and geomorphologist . The Thwaites Ice Shelf

2728-507: The Bight would have still been within the Southern Ocean in 1937 if the 2002 convention were in place then. To perform direct comparisons of current and former limits of oceans it is necessary to consider, or at least be aware of, how the 2002 change in IHO terminology for "seas" can affect the comparison. The Southern Ocean did not appear in the 1953 third edition of Limits of Oceans and Seas ,

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2816-604: The CIA World Fact Book ) which already adopted the principle that seas are contained within oceans. This difference in practice is markedly seen for the Pacific Ocean in the adjacent figure. Thus, for example, previously the Tasman Sea between Australia and New Zealand was not regarded by the IHO as part of the Pacific, but as of the 2002 draft edition it is. The new delineation of seas as subdivisions of oceans has avoided

2904-537: The Ellesmere Ice Shelf had been in place for at least 3,000 years. During the twentieth century, the Ellesmere Ice Shelf broke up into six separate shelves. From west to east, these were the Serson Ice Shelf , Petersen Ice Shelf , Milne Ice Shelf , Ayles Ice Shelf , Ward Hunt Ice Shelf , and Markham Ice Shelf . The smaller pieces continued to disintegrate. In April 2000, satellite images revealed that

2992-574: The Milne Ice Shelf, also ultimately experienced a major breakup at the end of July 2020, losing over 40% of its area. The Ellesmere Ice Shelf was the largest ice shelf in the Arctic, encompassing about 9,100 square kilometres (3,500 square miles) of the north coast of Ellesmere Island , Nunavut , Canada. The ice shelf was first documented by the British Arctic Expedition of 1875–76, in which Lieutenant Pelham Aldrich 's party went from Cape Sheridan to Cape Alert . The continuous mass of

3080-466: The National Geographic web site have begun to reference the Southern Ocean. A radical shift from past IHO practices (1928–1953) was also seen in the 2002 draft edition when the IHO delineated "seas" as subdivisions within the boundaries of "oceans". While the IHO are often considered the authority for such conventions, the shift brought them into line with the practices of other publications (e.g.

3168-515: The November 2006 sighting of several large icebergs from the coast of the South Island of New Zealand , the first time since 1931 that any icebergs had been observed from the New Zealand mainland. A large group of small icebergs (the largest some 1000 metres in length), were seen off the south-east coast of the island, with one of them drifting close enough to shore to be visible from the hills above

3256-583: The Pole". Francis Drake , like Spanish explorers before him, had speculated that there might be an open channel south of Tierra del Fuego. When Willem Schouten and Jacob Le Maire discovered the southern extremity of Tierra del Fuego and named it Cape Horn in 1615, they proved that the Tierra del Fuego archipelago was of small extent and not connected to the southern land, as previously thought. Subsequently, in 1642, Abel Tasman showed that even New Holland (Australia)

3344-697: The South Atlantic to the Cape of Good Hope between 55° and 60° . He thereby laid open the way for future Antarctic exploration by exploding the myth of a habitable southern continent. Cook's most southerly discovery of land lay on the temperate side of the 60th parallel , and he convinced himself that if land lay farther south it was practically inaccessible and without economic value. Voyagers rounding Cape Horn frequently met with contrary winds and were driven southward into snowy skies and ice-encumbered seas; but so far as can be ascertained none of them before 1770 reached

3432-657: The Southern Ocean as extending as far north as South America, and confers great significance on the Antarctic Convergence , yet its description of the Indian Ocean contradicts this, describing the Indian Ocean as extending south to Antarctica. Other sources, such as the National Geographic Society , show the Atlantic , Pacific , and Indian oceans as extending to Antarctica on its maps, although articles on

3520-458: The Southern Ocean as lying immediately south of Australia (see § Australian standpoint ). The National Geographic Society recognized the ocean officially in June 2021. Prior to this, it depicted it in a typeface different from the other world oceans; instead, it shows the Pacific, Atlantic, and Indian Oceans extending to Antarctica on both its print and online maps. Map publishers using

3608-554: The Southern Ocean was inspired by a belief in the existence of a Terra Australis – a vast continent in the far south of the globe to "balance" the northern lands of Eurasia and North Africa – which had existed since the times of Ptolemy . The rounding of the Cape of Good Hope in 1487 by Bartolomeu Dias first brought explorers within touch of the Antarctic cold, and proved that there was an ocean separating Africa from any Antarctic land that might exist. Ferdinand Magellan , who passed through

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3696-492: The Southern Ocean, using the definition that it lies south of 60th parallel, was surveyed by the Five Deeps Expedition in early February 2019. The expedition's multibeam sonar team identified the deepest point at 60° 28' 46"S, 025° 32' 32"W, with a depth of 7,434 metres (24,390 ft). The expedition leader and chief submersible pilot Victor Vescovo , has proposed naming this deepest point the "Factorian Deep", based on

3784-503: The Southern Ocean. In Australia, cartographical authorities define the Southern Ocean as including the entire body of water between Antarctica and the south coasts of Australia and New Zealand, and up to 60°S elsewhere. Coastal maps of Tasmania and South Australia label the sea areas as Southern Ocean and Cape Leeuwin in Western Australia is described as the point where the Indian and Southern Oceans meet. Exploration of

3872-611: The accumulation of snow, and often filling embayments in the coastline of an ice sheet." In contrast, sea ice is formed on water, is much thinner (typically less than 3 m (9.8 ft)), and forms throughout the Arctic Ocean . It is also found in the Southern Ocean around the continent of Antarctica . The term captured ice shelf has been used for the ice over a subglacial lake , such as Lake Vostok . Ice shelves are thick plates of ice, formed continuously by glaciers, that float atop an ocean. The shelves act as "brakes" for

3960-400: The area. Larsen B was stable for at least 10,000 years, essentially the entire Holocene period since the last glacial period. By contrast, Larsen A was absent for a significant part of that period, reforming about 4,000 years ago. Despite its great age, the Larsen B was clearly in trouble at the time of the collapse. With warm currents eating away the underside of the shelf, it had become

4048-673: The brilliant and erratic hydrographer who was nominated by the Royal Society to command the Transit of Venus expedition to Tahiti in 1769. The command of the expedition was given by the admiralty to Captain James Cook . Sailing in 1772 with Resolution , a vessel of 462 tons under his own command and Adventure of 336 tons under Captain Tobias Furneaux , Cook first searched in vain for Bouvet Island , then sailed for 20 degrees of longitude to

4136-453: The central part of the ice shelf at rates as high as 2 km per year. Satellite data, ground-penetrating radar, and GPS measurements taken in 2021 indicate that collapse of the ice shelf may be initiated by intersection of rifts with hidden basal crevasse zones as soon as 2026. Two sections of Antarctica's Larsen Ice Shelf broke apart into hundreds of unusually small fragments (hundreds of meters wide or less) in 1995 and 2002, Larsen C calved

4224-480: The circulation substantially slowing or even passing a tipping point and collapsing outright. The latter would have adverse impacts on global weather and the function of marine ecosystems here, unfolding over centuries. The ongoing warming is already changing marine ecosystems here. Borders and names for oceans and seas were internationally agreed when the International Hydrographic Bureau ,

4312-714: The city of Dunedin . If these were indeed the remnants of this calving, then over the course of five and a half years they had travelled slowly north and also east around over half the globe, a journey of some 13,500 km. From January 12 and January 13, 2010, an area of sea ice larger than the state of Rhode Island , or one-seventh the size of Wales , broke away from the Ronne–Filchner Ice Shelf and shattered into many smaller pieces. The Moderate-Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua and Terra satellites captured this event in this series of photo-like images. In May 2021, Iceberg A-76 broke off

4400-486: The coast of Tierra del Fuego with the coast of New Guinea on their globes, and allowing their imaginations to run riot in the vast unknown spaces of the south Atlantic, south Indian and Pacific oceans they sketched the outlines of the Terra Australis Incognita ("Unknown Southern Land"), a vast continent stretching in parts into the tropics. The search for this great south land was a leading motive of explorers in

4488-512: The decline of the ice of the peninsula. In October 1998, the iceberg A-38 broke off the Filchner–Ronne ice shelf. It had an extent of roughly 150 by 50 km and was thus larger than Delaware . It later broke up again into three parts. A similar-sized calving in May 2000 created an iceberg 167 by 32 km in extent, dubbed A-43 – the disintegration of this is thought to have been responsible for

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4576-433: The discovery of which he had received news at Cape Town , but from the rough determination of his longitude by Kerguelen, Cook reached the assigned latitude 10° too far east and did not see it. He turned south again and was stopped by ice in 61° 52′ S by 95° E and continued eastward nearly on the parallel of 60° S to 147° E . On 16 March, the approaching winter drove him northward for rest to New Zealand and

4664-549: The expedition regained Tahiti for refreshment. In November 1774, Cook started from New Zealand and crossed the South Pacific without sighting land between 53° and 57° S to Tierra del Fuego; then, passing Cape Horn on 29 December, he rediscovered Roché Island renaming it Isle of Georgia , and discovered the South Sandwich Islands (named Sandwich Land by him), the only ice-clad land he had seen, before crossing

4752-509: The floating ice is above the ocean surface, depending on how much pressurized air is contained in the bubbles within the glacial ice, stemming from compressed snow. The formula for the denominators above is 1 / [ ( ρ seawater − ρ glacial ice ) / ρ seawater ] {\textstyle 1/[(\rho _{\text{seawater}}-\rho _{\text{glacial ice}})/\rho _{\text{seawater}}]} , density of cold seawater

4840-647: The glaciers. These shelves serve another important purpose—"they moderate the amount of melting that occurs on the glaciers' surfaces. Once their ice shelves are removed, the glaciers increase in speed due to meltwater percolation and/or a reduction of braking forces, and they may begin to dump more ice into the ocean than they gather as snow in their catchments. Glacier ice speed increases are already observed in Peninsula areas where ice shelves disintegrated in prior years." The density contrast between glacial ice and liquid water means that at least ⁠ 1 / 9 ⁠ of

4928-473: The ice shelf. The Ellesmere ice shelf was reduced by 90% in the twentieth century, leaving the separate Alfred Ernest , Ayles , Milne , Ward Hunt , and Markham ice shelves. A 1986 survey of Canadian ice shelves found that 48 km (3.3 cubic kilometres) of ice calved from the Milne and Ayles ice shelves between 1959 and 1974. The Ayles Ice Shelf calved entirely on August 13, 2005. The Ward Hunt Ice Shelf,

5016-422: The ice shelves on Earth, nearly all of them are in Antarctica. In steady state, about half of Antarctica's ice shelf mass is lost to basal melt and half is lost to calving , but the relative importance of each process varies significantly between ice shelves. In recent decades, Antarctica's ice shelves have been out of balance, as they have lost more mass to basal melt and calving than has been replenished by

5104-448: The influx of new ice and snow. The Ross Ice Shelf is the largest ice shelf of Antarctica (as of 2013 , an area of roughly 500,809 square kilometres (193,363 sq mi) and about 800 kilometres (500 mi) across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than 600 kilometres (370 mi) long, and between 15 and 50 metres (50 and 160 ft) high above

5192-559: The island in 1775. Edmond Halley 's voyage in HMS ; Paramour for magnetic investigations in the South Atlantic met the pack ice in 52° S in January 1700, but that latitude (he reached 140 mi [230 km] off the north coast of South Georgia ) was his farthest south. A determined effort on the part of the French naval officer Jean-Baptiste Charles Bouvet de Lozier to discover

5280-493: The largest remaining section of thick (>10 meters (33 feet)) landfast sea ice along the northern coastline of Ellesmere Island, lost 600 square kilometers (230 square miles) of ice in a massive calving in 1961–1962. It further decreased by 27% in thickness (13 meters (43 feet)) between 1967 and 1999. In the summer of 2002, the Ward Ice Shelf experienced another major breakup, and other instances of note happened in 2008 and 2010 as well. The last remnant to remain mostly intact,

5368-415: The meridian of South East Cape , and the southern limits of the Great Australian Bight and the Tasman Sea were moved northward. The IHO readdressed the question of the Southern Ocean in a survey in 2000. Of its 68 member nations, 28 responded, and all responding members except Argentina agreed to redefine the ocean, reflecting the importance placed by oceanographers on ocean currents . The proposal for

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5456-534: The name Southern Ocean won 18 votes, beating the alternative Antarctic Ocean . Half of the votes supported a definition of the ocean's northern limit at the 60th parallel south —with no land interruptions at this latitude—with the other 14 votes cast for other definitions, mostly the 50th parallel south , but a few for as far north as the 35th parallel south . Notably the Southern Ocean Observing System collates data from latitudes higher than 40 degrees south. A draft fourth edition of Limits of Oceans and Seas

5544-490: The name of the crewed submersible DSV Limiting Factor , in which he successfully visited the bottom for the first time on February 3, 2019. By way of his voyages in the 1770s, James Cook proved that waters encompassed the southern latitudes of the globe. Yet, geographers have often disagreed on whether the Southern Ocean should be defined as a body of water bound by the seasonally fluctuating Antarctic Convergence - an oceanic zone where cold, northward flowing waters from

5632-467: The need to interrupt the northern boundary of the Southern Ocean where intersected by Drake Passage which includes all of the waters from South America to the Antarctic coast, nor interrupt it for the Scotia Sea , which also extends below the 60th parallel south. The new delineation of seas has also meant that the long-time named seas around Antarctica, excluded from the 1953 edition (the 1953 map did not even extend that far south), are automatically part of

5720-469: The north coast of Livingston Island ( South Shetlands ). It is unknown if some survivor managed to be the first to set foot on these Antarctic islands. The first confirmed sighting of mainland Antarctica cannot be accurately attributed to one single person. It can be narrowed down to three individuals. According to various sources, three men all sighted the ice shelf or the continent within days or months of each other: Fabian Gottlieb von Bellingshausen ,

5808-414: The northern limit of that circulation. The Southern Ocean overturning circulation is important because it makes up the second half of the global thermohaline circulation , after the better known Atlantic meridional overturning circulation (AMOC). Much like AMOC, it has also been substantially affected by climate change , in ways that have increased ocean stratification , and which may also result in

5896-434: The northern limit; the 1827 Edinburgh Gazetteer used 50 degrees. The Family Magazine in 1835 divided the "Great Southern Ocean" into the "Southern Ocean" and the "Antarctick [ sic ] Ocean" along the Antarctic Circle, with the northern limit of the Southern Ocean being lines joining Cape Horn, the Cape of Good Hope, Van Diemen's Land and the south of New Zealand. The United Kingdom's South Australia Act 1834 described

5984-424: The northwest corner of the shelf. At 4320 km , it is larger than Majorca , several times larger than Iceberg A-74 which calved in the same year, or approximately 14% the size of Belgium . The ice of the Filchner–Ronne ice shelf can be as thick as 600 m; the water below is about 1400 m deep at the deepest point. The international Filchner–Ronne Ice Shelf Programme (FRISP) was initiated in 1973 to study

6072-471: The ocean and its definition as the waters south of the 60th parallel south in its 2000 revisions, but this has not been formally adopted, due to continuing impasses about some of the content, such as the naming dispute over the Sea of Japan . The 2000 IHO definition was circulated as a draft edition in 2002, and is used by some within the IHO and other organizations, such as the CIA World Factbook and Merriam-Webster . The Australian Government regards

6160-438: The ocean's northern limit ceased to abut land masses. In the second edition, the Southern Ocean then extended from Antarctica northward to latitude 40°S between Cape Agulhas in Africa (long. 20°E) and Cape Leeuwin in Western Australia (long. 115°E), and extended to latitude 55°S between Auckland Island of New Zealand (165 or 166°E east) and Cape Horn in South America (67°W). As is discussed in more detail below, prior to

6248-432: The other new sea names within the "Southern Ocean", such as the " Cosmonauts Sea ") and Merriam-Webster , scientists and nations – and even by some within the IHO. Some nations' hydrographic offices have defined their own boundaries; the United Kingdom used the 55th parallel south for example. Other organisations favour more northerly limits for the Southern Ocean. For example, Encyclopædia Britannica describes

6336-499: The precursor to the IHO, convened the First International Conference on 24 July 1919. The IHO then published these in its Limits of Oceans and Seas , the first edition being 1928. Since the first edition, the limits of the Southern Ocean have moved progressively southward; since 1953, it has been omitted from the official publication and left to local hydrographic offices to determine their own limits. The IHO included

6424-597: The south, and South America, Africa, Australia, and Broughton Island, New Zealand to the north. The detailed land-limits used were from Cape Horn in Chile eastward to Cape Agulhas in Africa, then further eastward to the southern coast of mainland Australia to Cape Leeuwin , Western Australia . From Cape Leeuwin, the limit then followed eastward along the coast of mainland Australia to Cape Otway , Victoria , then southward across Bass Strait to Cape Wickham , King Island , along

6512-565: The term Southern Ocean on their maps include Hema Maps and GeoNova. "Southern Ocean" is an obsolete name for the Pacific Ocean or South Pacific, coined by the Spanish explorer Vasco Núñez de Balboa , the first European to discover the Pacific, who approached it from the north in Panama . The "South Seas" is a less archaic synonym. A 1745 British Act of Parliament established a prize for discovering

6600-519: The tropical islands of the Pacific. In November 1773, Cook left New Zealand, having parted company with the Adventure , and reached 60° S by 177° W , whence he sailed eastward keeping as far south as the floating ice allowed. The Antarctic Circle was crossed on 20 December and Cook remained south of it for three days, compelled after reaching 67° 31′ S to stand north again in 135° W . A long detour to 47° 50′ S served to show that there

6688-559: The two ships reached latitude 74°15' S and longitude 34°16'45″ W the southernmost position any ship had ever reached up to that time. A few icebergs were sighted but there was still no sight of land, leading Weddell to theorize that the sea continued as far as the South Pole. Another two days' sailing would have brought him to Coat's Land (to the east of the Weddell Sea ) but Weddell decided to turn back. The first land south of

6776-541: The upper surface and melting from the lower surface are also important to the mass balance of an ice shelf. Ice may also accrete onto the underside of the shelf. The effects of climate change are visible in the changes to the cryosphere , such as reduction in sea ice and ice sheets , and disruption of ice shelves. In the last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt, calving , and complete disintegration of some shelves. Well studied examples include disruptions of

6864-537: The water surface. Ninety percent of the floating ice, however, is below the water surface. All Canadian ice shelves are attached to Ellesmere Island and lie north of 82°N. Ice shelves that are still in existence are the Alfred Ernest Ice Shelf , Ward Hunt Ice Shelf , Milne Ice Shelf and Smith Ice Shelf . The M'Clintock Ice Shelf broke up from 1963 to 1966; the Ayles Ice Shelf broke up in 2005; and

6952-512: The waters forming the southern limit of the new province of South Australia as "the Southern Ocean". The Colony of Victoria 's Legislative Council Act 1881 delimited part of the division of Bairnsdale as "along the New South Wales boundary to the Southern ocean". In the 1928 first edition of Limits of Oceans and Seas , the Southern Ocean was delineated by land-based limits: Antarctica to

7040-556: The west coast of King Island, then the remainder of the way south across Bass Strait to Cape Grim , Tasmania . The limit then followed the west coast of Tasmania southward to the South East Cape and then went eastward to Broughton Island, New Zealand, before returning to Cape Horn. The northern limits of the Southern Ocean were moved southward in the IHO's 1937 second edition of the Limits of Oceans and Seas . From this edition, much of

7128-507: The westward in latitude 58° S , and then 30° eastward for the most part south of 60° S , a lower southern latitude than had ever been voluntarily entered before by any vessel. On 17 January 1773 the Antarctic Circle was crossed for the first time in history and the two ships reached 67° 15' S by 39° 35' E , where their course was stopped by ice. Cook then turned northward to look for French Southern and Antarctic Lands , of

7216-510: Was changed. A reservation had also been lodged by Australia regarding the Southern Ocean limits. Effectively, the third edition—which did not delineate the Southern Ocean leaving delineation to local hydrographic offices—has yet to be superseded. Despite this, the fourth edition definition has partial de facto usage by many nations, scientists, and organisations such as the U.S. (the CIA World Factbook uses "Southern Ocean", but none of

7304-458: Was circulated to IHO member states in August 2002 (sometimes referred to as the "2000 edition" as it summarized the progress to 2000). It has yet to be published due to 'areas of concern' by several countries relating to various naming issues around the world – primarily the Sea of Japan naming dispute – and there have been various changes, 60 seas were given new names, and even the name of the publication

7392-523: Was later named the Ross Ice Shelf . Mount Erebus and Mount Terror are named after two ships from his expedition: HMS  Erebus and HMS  Terror . The Imperial Trans-Antarctic Expedition of 1914, led by Ernest Shackleton , set out to cross the continent via the pole, but their ship, Endurance , was trapped and crushed by pack ice before they even landed. The expedition members survived after an epic journey on sledges over pack ice to Elephant Island . Then Shackleton and five others crossed

7480-526: Was located approximately 800 km (500 mi) south of the North Pole , broke away from the coast forming the giant Ayles Ice Island 37 metres (121 ft) thick and measuring around 14 by 5 km (8.7 by 3.1 mi) in size with an area of approximately 66 km (25 sq mi) or 2.6 km (0.62 cu mi) in volume. Southern Ocean Main five oceans division: Further subdivision: The Southern Ocean , also known as

7568-418: Was no land connection between New Zealand and Tierra del Fuego . Turning south again, Cook crossed the Antarctic Circle for the third time at 109° 30′ W before his progress was once again blocked by ice four days later at 71° 10′ S by 106° 54′ W . This point, reached on 30 January 1774, was the farthest south attained in the 18th century. With a great detour to the east, almost to the coast of South America,

7656-479: Was separated by sea from any continuous southern continent. The visit to South Georgia by Anthony de la Roché in 1675 was the first-ever discovery of land south of the Antarctic Convergence , i.e. in the Southern Ocean/Antarctic. Soon after the voyage cartographers started to depict " Roché Island ", honouring the discoverer. James Cook was aware of la Roché's discovery when surveying and mapping

7744-511: Was then known, and reported the discovery "of an Antarctic continent west of the Balleny Islands " on 25 January 1840. That part of Antarctica was later named " Wilkes Land ", a name it maintains to this day. Explorer James Clark Ross passed through what is now known as the Ross Sea and discovered Ross Island (both of which were named for him) in 1841. He sailed along a huge wall of ice that

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