TheSouthern Ocean, also known as theAntarctic Ocean,[1][note 4] comprises the southernmost waters of theworld ocean, generally taken to be south of60° S latitude and encirclingAntarctica.[5] With a size of 21,960,000 km2 (8,480,000 sq mi), it is the second-smallest of the five principal oceanic divisions, smaller than thePacific,Atlantic andIndian oceans, and larger than theArctic Ocean.[6]
The maximum depth of the Southern Ocean, using the definition that it lies south of 60th parallel, was surveyed by theFive 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 the name of the crewed submersibleDSV Limiting Factor, in which he successfully visited the bottom for the first time on February 3, 2019.[7]
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 fluctuatingAntarctic Convergence — anoceanic zone where cold, northward flowing waters from the Antarctic mix with warmerSubantarctic waters[8] — or not defined at all, with its waters instead treated as the southern limits of the Pacific, Atlantic, and Indian oceans. TheInternational Hydrographic Organization (IHO) finally settled the debate after the full importance ofSouthern Ocean overturning circulation had been ascertained, and the termSouthern Ocean now defines the body of water which lies south of the northern limit of that circulation.[9]
The Southern Ocean overturning circulation is important because it makes up the second half of the globalthermohaline circulation, after the better knownAtlantic meridional overturning circulation (AMOC).[10] Much like AMOC, it has also been substantially affected byclimate change, in ways that have increasedocean stratification,[11] and which may also result in the circulation substantially slowing or even passing atipping point and collapsing outright. The latter would have adverse impacts on global weather and the function ofmarine ecosystems here, unfolding over centuries.[12][13] The ongoing warming is already changing marine ecosystems here.[14]
TheInternational Hydrographic Organization's delineation of the "Southern Ocean" has moved steadily southward since the original 1928 edition of itsLimits of Oceans and Seas.[5]
Borders and names for oceans and seas were internationally agreed when theInternational Hydrographic Bureau, the precursor to the IHO, convened the First International Conference on 24 July 1919. The IHO then published these in itsLimits 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 the ocean and its definition as the waters south of the60th parallel south in its 2000 revisions, but this has not been formally adopted, due to continuing impasses about some of the content, such as thenaming dispute over theSea 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 theCIA World Factbook andMerriam-Webster.[6][15]
The Australian Government regards the Southern Ocean as lying immediately south of Australia (see§ Australian standpoint).[16][17]
TheNational Geographic Society recognized the ocean officially in June 2021.[18][19] Prior to this, it depicted it in a typeface different from the other world oceans; instead, it showed the Pacific, Atlantic, and Indian Oceans extending to Antarctica on both its print and online maps.[20][21] Map publishers using the term Southern Ocean on their maps include Hema Maps[22] and GeoNova.[23]
"Southern Ocean" as alternative to theAethiopian Ocean, 18th century
"Southern Ocean" is an obsolete name for the Pacific Ocean or South Pacific, coined by the Spanish explorerVasco Núñez de Balboa, the first European to discover the Pacific, who approached it from the north inPanama.[24] The "South Seas" is a less archaic synonym. A 1745 BritishAct of Parliament established a prize for discovering aNorthwest Passage to "the Western and Southern Ocean ofAmerica".[25]
Authors using "Southern Ocean" to name the waters encircling the unknown southern polar regions used varying limits.James Cook's account ofhis second voyage impliesNew Caledonia borders it.[26] Peacock's 1795Geographical Dictionary said it lay "to the southward of America and Africa";[27] John Payne in 1796 used 40 degrees as the northern limit;[28] the 1827Edinburgh Gazetteer used 50 degrees.[29] TheFamily 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.[30]
In the 1928 first edition ofLimits of Oceans and Seas, the Southern Ocean was delineated by land-based limits: Antarctica to the south, and South America, Africa, Australia, andBroughton Island, New Zealand to the north.
The detailed land-limits used were fromCape Horn in Chile eastward toCape Agulhas in Africa, then further eastward to the southern coast of mainland Australia toCape Leeuwin,Western Australia. From Cape Leeuwin, the limit then followed eastward along the coast of mainland Australia toCape Otway,Victoria, then southward acrossBass Strait toCape Wickham,King Island, along the west coast of King Island, then the remainder of the way south across Bass Strait toCape Grim,Tasmania.
The limit then followed the west coast of Tasmania southward to theSouth East Cape and then went eastward to Broughton Island, New Zealand, before returning to Cape Horn.[32]
The northern limits of the Southern Ocean were moved southward in the IHO's 1937 second edition of theLimits of Oceans and Seas. From this edition, much of 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 betweenCape Agulhas in Africa (long. 20°E) andCape Leeuwin in Western Australia (long. 115°E), and extended to latitude 55°S betweenAuckland Island of New Zealand (165 or 166°E east) andCape Horn in South America (67°W).[33]
As is discussed in more detail below, prior to the 2002 edition the limits of oceans explicitly excluded the seas lying within each of them. TheGreat 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 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 ofLimits of Oceans and Seas, 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 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.)[34]: 4
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 the meridian ofSouth East Cape, and the southern limits of theGreat Australian Bight and theTasman Sea were moved northward.[34]
Area inside the black line indicates the area constituting the Pacific Ocean prior to 2002; darker blue areas are its informal current borders following the recreation of the Southern Ocean and the reinclusion of marginal seas.[35]
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 onocean currents. The proposal for the nameSouthern Ocean won 18 votes, beating the alternativeAntarctic Ocean. Half of the votes supported a definition of the ocean's northern limit at the60th parallel south—with no land interruptions at this latitude—with the other 14 votes cast for other definitions, mostly the50th parallel south, but a few for as far north as the35th parallel south. Notably, theSouthern Ocean Observing System collates data from latitudes higher than 40 degrees south.
A draft fourth edition ofLimits of Oceans and Seas was circulated to IHO member states in August 2002 (sometimes referred to as the "2000 edition" as it summarized the progress to 2000).[36] It has yet to be published due to 'areas of concern' by several countries relating to various naming issues around the world – primarily theSea of Japan naming dispute – and there have been various changes: 60 seas were given new names, and even the name of the publication was changed.[37] A reservation had also been lodged by Australia regarding the Southern Ocean limits.[38] Effectively, the third edition—which did not delineate the Southern Ocean leaving delineation to local hydrographic offices—has yet to be superseded.
Continents and islands of the Southern Ocean
Despite this, the fourth edition definition has partialde facto usage by many nations, scientists, and organisations such as the U.S. (theCIA World Factbook uses "Southern Ocean", but none of the other new sea names within the "Southern Ocean", such as the "Cosmonauts Sea") andMerriam-Webster,[6][15][21] scientists and nations – and even by some within the IHO.[39] Some nations' hydrographic offices have defined their own boundaries; the United Kingdom used the55th parallel south for example.[34] Other organisations favour more northerly limits for the Southern Ocean. For example,Encyclopædia Britannica describes the Southern Ocean as extending as far north as South America, and confers great significance on theAntarctic Convergence, yet its description of the Indian Ocean contradicts this, describing the Indian Ocean as extending south to Antarctica.[40][41]
Other sources, such as theNational Geographic Society, show theAtlantic,Pacific, andIndian oceans as extending to Antarctica on its maps, although articles on the National Geographic web site have begun to reference the Southern Ocean.[21]
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. the CIAWorld Fact Book) which already adopted the principle that seas are contained within oceans. This difference in practice is markedly seen for thePacific Ocean in the adjacent figure. Thus, for example, previously theTasman 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 the need to interrupt the northern boundary of the Southern Ocean where intersected byDrake Passage which includes all of the waters from South America to the Antarctic coast, nor interrupt it for theScotia 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 the Southern Ocean.
A map of Australia's official interpretation of the names and limits of oceans and seas around Australia
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.[42] Coastal maps ofTasmania andSouth Australia label the sea areas asSouthern Ocean[43] andCape Leeuwin inWestern Australia is described as the point where the Indian and Southern Oceans meet.[44]
The 1564Typus Orbis Terrarum, a map byAbraham Ortelius, showed the imagined link between the proposed continent of Antarctica andSouth America.
Exploration of the Southern Ocean was inspired by a belief in the existence of aTerra 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 ofPtolemy. The rounding of theCape of Good Hope in 1487 byBartolomeu 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.[45]Ferdinand Magellan, who passed through theStrait of Magellan in 1520, assumed that the islands ofTierra 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 theRegio Patalis withLocach as a northward extension of theTerra Australis, reaching as far asNew Guinea.[46][47]
European geographers continued to connect 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 theTerra 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 the 16th and the early part of the 17th centuries.[45]
TheSpaniardGabriel de Castilla, who claimed having sighted "snow-covered mountains" beyond the64° 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 (theNew Hebrides) and those he would discover "even to the Pole".[45]
Francis Drake, like Spanish explorers before him, had speculated that there might be an open channel south of Tierra del Fuego. WhenWillem Schouten andJacob Le Maire discovered the southern extremity of Tierra del Fuego and named itCape 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 evenNew Holland (Australia) was separated by sea from any continuous southern continent.[45]
The visit toSouth Georgia byAnthony de la Roché in 1675 was the first-ever discovery of land south of theAntarctic Convergence, i.e. in the Southern Ocean/Antarctic.[48][49] 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 the island in 1775.[50]
Edmond Halley's voyage inHMS Paramour for magnetic investigations in the South Atlantic met the pack ice in52° S in January 1700, but that latitude (he reached 140 mi [230 km] off the north coast ofSouth Georgia) was his farthest south. A determined effort on the part of the French naval officerJean-Baptiste Charles Bouvet de Lozier to discover the "South Land" – described by a half legendary "sieur de Gonneyville" – resulted in the discovery ofBouvet Island in 54°10′ S, and in the navigation of48° of longitude of ice-cumbered sea nearly in55° S in 1730.[45]
In 1771,Yves Joseph Kerguelen sailed fromFrance with instructions to proceed south fromMauritius in search of "a very large continent". He lighted upon a land in50° 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 whichwas ultimately named after him.[45]
"Terres Australes" [sic] label without any charted landmassJames Weddell's second expedition in 1823, depicting the brigJane and thecutterBeaufroy
The obsession of the undiscovered continent culminated in the brain ofAlexander Dalrymple, the brilliant and erratichydrographer who was nominated by theRoyal Society to command theTransit of Venus expedition toTahiti in 1769. The command of the expedition was given by the admiralty to CaptainJames Cook. Sailing in 1772 withResolution, a vessel of 462 tons under his own command andAdventure of 336 tons under CaptainTobias Furneaux, Cook first searched in vain forBouvet Island, then sailed for 20 degrees of longitude to the westward inlatitude 58° S, and then 30° eastward for the most part south of60° S, a lower southern latitude than had ever been voluntarily entered before by any vessel. On 17 January 1773 theAntarctic Circle was crossed for the first time in history and the two ships reached67° 15' S by39° 35' E, where their course was stopped by ice.[45]
Famous official portrait of CaptainJames Cook who proved that waters encompassed the southern latitudes of the globe."He holds his own chart of the Southern Ocean on the table and his right hand points to the east coast of Australia on it."[51]
Cook then turned northward to look forFrench Southern and Antarctic Lands, of the discovery of which he had received news atCape 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 in61° 52′ S by 95° E and continued eastward nearly on the parallel of60° S to147° E. On 16 March, the approaching winter drove him northward for rest to New Zealand and the tropical islands of the Pacific. In November 1773, Cook left New Zealand, having parted company with theAdventure, and reached60° S by177° 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 reaching67° 31′ S to stand north again in135° W.[45]
A long detour to47° 50′ S served to show that there was no land connection between New Zealand andTierra del Fuego. Turning south again, Cook crossed the Antarctic Circle for the third time at109° 30′ W before his progress was once again blocked by ice four days later at71° 10′ S by106° 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, the expedition regained Tahiti for refreshment. In November 1774, Cook started from New Zealand and crossed the South Pacific without sighting land between53° and57° S to Tierra del Fuego; then, passing Cape Horn on 29 December, he rediscoveredRoché Island renaming itIsle of Georgia, and discovered theSouth Sandwich Islands (namedSandwich Land by him), the only ice-clad land he had seen, before crossing the South Atlantic to the Cape of Good Hope between55° and60°. 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 the60th parallel, and he convinced himself that if land lay farther south it was practically inaccessible and without economic value.[45]
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 the Antarctic Circle, or knew it, if they did.
In a voyage from 1822 to 1824,James Weddell commanded the 160-tonbrigJane, accompanied by his second shipBeaufoy captained by Matthew Brisbane. Together they sailed to the South Orkneys wheresealing 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 the two ships reachedlatitude 74°15' S andlongitude 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 toCoat's Land (to the east of theWeddell Sea) but Weddell decided to turn back.[52]
In the meantime, the Spanish Navy shipSan Telmo sank in September 1819 when trying to cross Cape Horn. Parts of her wreckage were found months later by sealers on the north coast ofLivingston Island (South Shetlands). It is unknown if some survivor managed to be the first to set foot on these Antarctic islands.
Historical maps showing a southern ocean between Antarctica and the continents of South America, Africa and Australia
1683 map by French cartographerAlain Manesson Mallet from his publicationDescription de L'Univers. Shows a sea below both the Atlantic and Pacific oceans at a time whenTierra del Fuego was believed joined to Antarctica. Sea is namedMer Magellanique afterFerdinand Magellan.
A New Map of Asia, from the Latest Authorities, byJohn Cary, Engraver, 1806, shows theSouthern Ocean lying to the south of both the Indian Ocean and Australia.
Freycinet Map of 1811 – resulted from the 1800–1803 FrenchBaudin expedition to Australia and was the first full map of Australia ever to be published. In French, the map named the ocean immediately below Australia as theGrand Océan Austral ('Great Southern Ocean').
1863 map of Australia shows theSouthern Ocean lying immediately to the south of Australia.
1906 map by German publisherJustus Perthes showing Antarctica encompassed by anAntarktischer (Sudl. Eismeer) Ocean – the 'Antarctic (South Arctic) Ocean'.
USS Vincennes at Disappointment Bay, Antarctica in early 18401911 South Polar Regions exploration map
In December 1839, as part of theUnited States Exploring Expedition of 1838–42 conducted by theUnited States Navy (sometimes called "the Wilkes Expedition"), an expedition sailed from Sydney, Australia, on the sloops-of-warUSS Vincennes andUSS Peacock, the brigUSS Porpoise, the full-rigged shipRelief, and two schoonersSea Gull andUSS Flying Fish. They sailed into the Antarctic Ocean, as it was then known, and reported the discovery "of an Antarctic continent west of theBalleny Islands" on 25 January 1840. That part of Antarctica was later named "Wilkes Land", a name it maintains to this day.
TheImperial Trans-Antarctic Expedition of 1914, led byErnest 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 toElephant Island. Then Shackleton and five others crossed the Southern Ocean, in an open boat calledJames Caird, and then trekked overSouth Georgia to raise the alarm at the whaling stationGrytviken.
In 1946, US Navy Rear AdmiralRichard E. Byrd and more than 4,700 military personnel visited the Antarctic in an expedition calledOperation Highjump. Reported to the public as a scientific mission, the details were kept secret and it may have actually been a training or testing mission for the military. The expedition was, in both military or scientific planning terms, put together very quickly. The group contained an unusually high amount of military equipment, including an aircraft carrier, submarines, military support ships, assault troops and military vehicles. The expedition was planned to last for eight months but was unexpectedly terminated after only two months. With the exception of some eccentric entries in Admiral Byrd's diaries, no real explanation for the early termination has ever been officially given.
CaptainFinn Ronne, Byrd's executive officer, returned to Antarctica withhis own expedition in 1947–1948, with Navy support, three planes, and dogs. He disproved the notion that the continent was divided in two and established that East and West Antarctica was one single continent, i.e. that the Weddell Sea and the Ross Sea are not connected.[58] The expedition explored and mapped large parts of Palmer Land and the Weddell Sea coastline, and identified theRonne Ice Shelf, named by him for his wifeJackie Ronne.[59] He covered 3,600 miles (5,790 km) by ski and dog sled – more than any other explorer in history.[60] TheRonne Antarctic Research Expedition discovered and mapped the last unknown coastline in the world and was the first Antarctic expedition to ever include women.[61]
MSExplorer in Antarctica in January 1999. She sank on 23 November 2007 after hitting aniceberg.
TheAntarctic Treaty was signed on 1 December 1959 and came into force on 23 June 1961. Among other provisions, this treaty limitsmilitary activity in the Antarctic to the support of scientific research.
The first person to sail single-handed to Antarctica was the New ZealanderDavid Henry Lewis, in 1972, in a 10-metre (30 ft) steel sloopIce Bird.
A baby, namedEmilio Marcos de Palma, was born nearHope Bay on 7 January 1978, becoming the first baby born on the continent. He also was born further south than anyone in history.[62]
TheMV Explorer was acruise ship operated by theSwedish explorerLars-Eric Lindblad. Observers point toExplorer's 1969 expeditionary cruise toAntarctica as the frontrunner for today's[when?] sea-based tourism in that region.[63][64]Explorer was the first cruise ship used specifically to sail the icy waters of the Antarctic Ocean and the first to sink there[65] when she struck an unidentified submerged object on 23 November 2007, reported to be ice, which caused a 10 by 4 inches (25 by 10 cm) gash in the hull.[66]Explorer was abandoned in the early hours of 23 November 2007 after taking on water near theSouth Shetland Islands in the Southern Ocean, an area which is usually stormy but was calm at the time.[67]Explorer was confirmed by theChilean Navy to have sunk at approximately position: 62° 24′ South, 57° 16′ West,[68] in roughly 600 m of water.[69]
British engineerRichard Jenkins designed anunmanned saildrone[70] that completed the first autonomous circumnavigation of the Southern Ocean on 3 August 2019 after 196 days at sea.[71]
The first completelyhuman-powered expedition on the Southern Ocean was accomplished on 25 December 2019 by a team of rowers comprising captainFiann Paul (Iceland), first mateColin O'Brady (US),Andrew Towne (US),Cameron Bellamy (South Africa), Jamie Douglas-Hamilton (UK) and John Petersen (US).[72]
The Southern Ocean, geologically the youngest of the oceans, was formed when Antarctica andSouth America moved apart, opening theDrake Passage, roughly 30 million years ago. The separation of the continents allowed the formation of theAntarctic Circumpolar Current.
With a northern limit at60°S, the Southern Ocean differs from the other oceans in that its largest boundary, the northern boundary, does not abut a landmass (as it did with the first edition ofLimits of Oceans and Seas). Instead, the northern limit is with the Atlantic, Indian and Pacific Oceans.
One reason for considering it as a separate ocean stems from the fact that much of the water of the Southern Ocean differs from the water in the other oceans. Water gets transported around the Southern Ocean fairly rapidly because of theAntarctic Circumpolar Current which circulates around Antarctica. Water in the Southern Ocean south of, for example, New Zealand, resembles the water in the Southern Ocean south of South America more closely than it resembles the water in the Pacific Ocean.
The Southern Ocean has typical depths of between 4,000 and 5,000 m (13,000 and 16,000 ft) over most of its extent with only limited areas of shallow water. The Southern Ocean's greatest depth of 7,236 m (23,740 ft) occurs at the southern end of theSouth Sandwich Trench, at 60°00'S, 024°W. TheAntarctic continental shelf appears generally narrow and unusually deep, its edge lying at depths up to 800 m (2,600 ft), compared to a global mean of 133 m (436 ft).
Equinox to equinox in line with the sun's seasonal influence, the Antarctic ice pack fluctuates from an average minimum of 2.6 million square kilometres (1.0×10^6 sq mi) in March to about 18.8 million square kilometres (7.3×10^6 sq mi) in September, more than a sevenfold increase in area.
Subdivisions of oceans are geographical features such as "seas", "straits", "bays", "channels", and "gulfs". There are many sudivisions of the Southern Ocean defined in the never-approved 2002 draft fourth edition of the IHO publicationLimits of Oceans and Seas. In clockwise order these include (with sector):
A number of these such as the 2002 Russian-proposed "Cosmonauts Sea", "Cooperation Sea", and "Somov (mid-1950s Russian polar explorer) Sea" are not included in the 1953 IHO document which remains currently in force,[34] because they received their names largely originated from 1962 onward. Leading geographic authorities and atlases do not use these latter three names, including the 2014 10th edition World Atlas from the United States'National Geographic Society and the 2014 12th edition of the BritishTimes Atlas of the World, but Soviet and Russian-issued maps do.[73][74]
The Southern Ocean probably contains large, and possibly giant,oil andgas fields on thecontinental margin.Placer deposits, accumulation of valuable minerals such as gold, formed by gravity separation during sedimentary processes are also expected to exist in the Southern Ocean.[5]
Manganese nodules are expected to exist in the Southern Ocean. Manganese nodules are rockconcretions on thesea bottom formed of concentric layers ofiron andmanganesehydroxides around a core. The core may be microscopically small and is sometimes completely transformed into manganese minerals bycrystallization. Interest in the potential exploitation of polymetallic nodules generated a great deal of activity among prospective mining consortia in the 1960s and 1970s.[5]
Theicebergs that form each year around in the Southern Ocean hold enoughfresh water to meet the needs of every person on Earth for several months. For several decades there have been proposals, none yet to be feasible or successful, to tow Southern Ocean icebergs to more arid northern regions (such as Australia) where they can be harvested.[78]
Icebergs can occur at any time of year throughout the ocean. Some may have drafts up to several hundred meters; smaller icebergs, iceberg fragments and sea-ice (generally 0.5 to 1 m thick) also pose problems for ships. The deep continental shelf has a floor of glacial deposits varying widely over short distances.
Sailors know latitudes from40 to70 degrees south as the "Roaring Forties", "Furious Fifties" and "Shrieking Sixties" due to high winds and large waves that form as winds blow around the entire globe unimpeded by any land-mass. Icebergs, especially in May to October, make the area even more dangerous. The remoteness of the region makes sources of search and rescue scarce.
While the Southern is the second smallest ocean it contains the unique and highly energeticAntarctic Circumpolar Current which moves perpetually eastward – chasing and joining itself, and at 21,000 km (13,000 mi) in length – it comprises the world's longest ocean current, transporting 130 million cubic metres per second (4.6×10^9 cu ft/s) of water – 100 times the flow of all the world's rivers.[79]
Associated with the Circumpolar Current is theAntarctic Convergence encircling Antarctica, where cold northward-flowing Antarctic waters meet the relatively warmer waters of thesubantarctic, Antarctic waters predominantly sink beneath subantarctic waters, while associated zones of mixing andupwelling create a zone very high in nutrients. These nurture high levels ofphytoplankton with associated copepods andAntarctic krill, and resultant foodchains supporting fish, whales, seals, penguins, albatrosses and a wealth of other species.[80]
The Antarctic Convergence is considered to be the best natural definition of the northern extent of the Southern Ocean.
Large-scaleupwelling is found in the Southern Ocean. Strong westerly (eastward) winds blow aroundAntarctica, driving a significant flow of water northward. This is actually a type of coastal upwelling. Since there are no continents in a band of open latitudes betweenSouth America and the tip of theAntarctic Peninsula, some of this water is drawn up from great depths. In many numerical models and observational syntheses, the Southern Ocean upwelling represents the primary means by which deep dense water is brought to the surface. Shallower, wind-driven upwelling is also found off the west coasts of North and South America, northwest and southwest Africa, and southwest andsoutheast Australia, all associated with oceanic subtropical high pressure circulations.
Sea ice has been noted to persist in the central area of the Ross Gyre.[81] There is some evidence thatglobal warming has resulted in some decrease of thesalinity of the waters of the Ross Gyre since the 1950s.[82]
Due to theCoriolis effect acting to the left in theSouthern Hemisphere and the resultingEkman transport away from the centres of the Weddell Gyre, these regions are very productive due to upwelling of cold, nutrient rich water.
Observation of the Southern Ocean is coordinated through theSouthern Ocean Observing System (SOOS).[83][84] This provides access to meta data for a significant proportion of the data collected in the regions over the past decades including hydrographic measurements and ocean currents. The data provision is set up to emphasize records that are related toEssential Ocean Variables (EOVs)[85] for the ocean region south of 40°S.
Sea temperatures vary from about −2 to 10 °C (28 to 50 °F). Cyclonic storms travel eastward around the continent and frequently become intense because of the temperature contrast between ice andopen ocean. The ocean from aboutlatitude 40 south to the Antarctic Circle has the strongest average winds found anywhere on Earth.[86] In winter the ocean freezes outward to65 degrees south latitude in the Pacific sector and55 degrees south latitude in the Atlantic sector, lowering surface temperatures well below 0 degrees Celsius. At some coastal points, persistent intense drainage winds from the interior keep the shoreline ice-free throughout the winter.
Clouds over the Southern Ocean, with continent labels
Even under the most intense climate change scenario, which is currently considered unlikely,[91][92] the Southern Ocean would continue to function as a strong sink in the 21st century, and take up an increasing amount ofcarbon dioxide (left) and heat (middle). However, it would take up a smallerfraction of heat per every additional degree of warming than it does now (right),[93] as well as a smallerfraction of emissions.[94]
As human-causedgreenhouse gas emissions cause increased warming, one of the most notableeffects of climate change on oceans is the increase inocean heat content, which accounted for over 90% of the totalglobal heating since 1971.[95] Since 2005, from 67% to 98% of this increase has occurred in the Southern Ocean.[96] InWest Antarctica, the temperature in the upper layer of the ocean has warmed 1 °C (1.8 °F) since 1955, and theAntarctic Circumpolar Current (ACC) is also warming faster than the global average.[97] This warming directly affects the flow of warm and cold water masses which make up the overturning circulation, and it also reduces the cover ofsea ice (which is highly reflective and so elevates thealbedo of Earth's surface) in theSouthern Hemisphere, as well asmass balance of Antarctica's ice shelves and peripheral glaciers.[98] For these reasons,climate models consistently show that the year when global warming will reach 2 °C (3.6 °F) (inevitable in allclimate change scenarios wheregreenhouse gas emissions have not been strongly lowered) depends on the status of the circulation more than any other factor besides the emissions themselves.[99]
Greater warming of this ocean water increases ice loss from Antarctica, and also generates more freshmeltwater, at a rate of 1100–1500 billion tons (GT) per year.[98]: 1240 This meltwater from theAntarctic ice sheet then mixes back into the Southern Ocean, making its water fresher.[100] This freshening of the Southern Ocean causes increased stratification and stabilization of its layers,[101][98]: 1240 [102] and this has the single largest impact on the long-term properties of Southern Ocean circulation.[103] These changes in the Southern Ocean cause the upper cell circulation to speed up, accelerating the flow of major currents,[104] while the lower cell circulation slows down, as it is dependent on the highly salineAntarctic bottom water, which already appears to have been observably weakened by the freshening, in spite of the limited recovery during 2010s.[105][106][107][98]: 1240 Since the 1970s, the upper cell has strengthened by 3–4sverdrup (Sv; represents a flow of 1 millioncubic meters per second), or 50–60% of its flow, while the lower cell has weakened by a similar amount, but because of its larger volume, these changes represent a 10–20% weakening.[108][89] However, they were not fully caused by climate change, as the natural cycle ofInterdecadal Pacific Oscillation had also played an important role.[109][110]
Since the 1970s, the upper cell of the circulation has strengthened, while the lower cell weakened.[89]Evidence suggests that the Antarctic bottom water requires a temperature range close to current conditions to be at full strength. During theLast Glacial Maximum (a cold period), it was too weak to flow out of theWeddell Sea and the overturning circulation was much weaker than now. It was also weaker during the periods warmer than now.[111]
Similar processes are taking place withAtlantic meridional overturning circulation (AMOC), which is also affected by the ocean warming and by meltwater flows from the decliningGreenland ice sheet.[112] It is possible that both circulations may not simply continue to weaken in response to increased warming and freshening, but eventually collapse to a much weaker state outright, in a way which would be difficult to reverse and constitute an example oftipping points in the climate system.[99] There ispaleoclimate evidence for the overturning circulation being substantially weaker than now during past periods that were both warmer and colder than now.[111] However,Southern Hemisphere is only inhabited by 10% of the world's population, and the Southern Ocean overturning circulation has historically received much less attention than the AMOC. Consequently, while multiple studies have set out to estimate the exact level of global warming which could result in AMOC collapsing, the timeframe over which such collapse may occur, and the regional impacts it would cause, much less equivalent research exists for the Southern Ocean overturning circulation as of the early 2020s. There has been a suggestion that its collapse may occur between 1.7 °C (3.1 °F) and 3 °C (5.4 °F), but this estimate is much less certain than for many other tipping points.[99]
The impacts of Southern Ocean overturning circulation collapse have also been less closely studied, though scientists expect them to unfold over multiple centuries. A notable example is the loss ofnutrients from Antarctic bottom water diminishing ocean productivity and ultimately the state of Southern Oceanfisheries, potentially leading to theextinction of some species offish, and thecollapse of somemarine ecosystems.[113] Reduced marine productivity would also mean that the ocean absorbs less carbon (though not within the 21st century[93]), which could increase the ultimate long-term warming in response to anthropogenic emissions (thus raising the overallclimate sensitivity) and/or prolong the time warming persists before it starts declining on the geological timescales.[87] There is also expected to be a decline inprecipitation in theSouthern Hemisphere countries likeAustralia, with a corresponding increase in theNorthern Hemisphere. However, the decline or an outright collapse of the AMOC would have similar but opposite impacts, and the two would counteract each other up to a point. Both impacts would also occur alongside the othereffects of climate change on the water cycle andeffects of climate change on fisheries.[113]
Thebenthic communities of the seafloor are diverse and dense, with up to 155,000 animals found in 1 square metre (10.8 sq ft). As the seafloor environment is very similar all around the Antarctic, hundreds of species can be found all the way around the mainland, which is a uniquely wide distribution for such a large community.Deep-sea gigantism is common among these animals.[115]
A census of sea life carried out during theInternational Polar Year and which involved some 500 researchers was released in 2010. The research is part of the globalCensus of Marine Life (CoML) and has disclosed some remarkable findings. More than 235 marine organisms live in both polar regions, having bridged the gap of 12,000 km (7,500 mi). Large animals such as some cetaceans and birds make the round trip annually. More surprising are small forms of life such as mudworms,sea cucumbers and free-swimming snails found in both polar oceans. Various factors may aid in their distribution – fairly uniform temperatures of the deep ocean at the poles and the equator which differ by no more than 5 °C (9.0 °F), and the major current systems or marineconveyor belt which transport egg and larva stages.[116] Among smaller marine animals generally assumed to be the same in the Antarctica and the Arctic, more detailed studies of each population have often—but not always—revealed differences, showing that they are closely relatedcryptic species rather than a single bipolar species.[117][118][119]
The flightlesspenguins are all located in theSouthern Hemisphere, with the greatest concentration located on and around Antarctica. Four of the 18 penguin species live and breed on the mainland and its close offshore islands. Another four species live on the subantarctic islands.[122]Emperor penguins have four overlapping layers of feathers, keeping them warm. They are the only Antarctic animal to breed during the winter.[123]
There are relatively few fish species in fewfamilies in the Southern Ocean. The most species-rich family are thesnailfish (Liparidae), followed by thecod icefish (Nototheniidae)[124] andeelpout (Zoarcidae). Together the snailfish, eelpouts andnotothenioids (which includes cod icefish and several other families) account for almost9⁄10 of the more than 320 described fish species of the Southern Ocean (tens ofundescribed species also occur in the region, especially among the snailfish).[125] Southern Ocean snailfish are generally found in deep waters, while the icefish also occur in shallower waters.[124]
Fish of theNotothenioidei suborder, such as this young icefish, are mostly restricted to the Antarctic and Subantarctic.
Cod icefish (Nototheniidae), as well as several other families, are part of theNotothenioidei suborder, collectively sometimes referred to as icefish. The suborder contains many species withantifreeze proteins in their blood and tissue, allowing them to live in water that is around or slightly below 0 °C (32 °F).[126][127] Antifreeze proteins are also known from Southern Ocean snailfish.[128]
Thecrocodile icefish (family Channichthyidae), also known as white-blooded fish, are only found in the Southern Ocean. They lackhemoglobin in their blood, resulting in their blood being colourless. One Channichthyidae species, themackerel icefish (Champsocephalus gunnari), was once the most common fish in coastal waters less than 400 metres (1,312 ft) deep, but wasoverfished in the 1970s and 1980s. Schools of icefish spend the day at the seafloor and the night higher in thewater column eating plankton and smaller fish.[126]
There are two species from the genusDissostichus, theAntarctic toothfish (Dissostichus mawsoni) and thePatagonian toothfish (Dissostichus eleginoides). These two species live on the seafloor 100–3,000 metres (328–9,843 ft) deep, and can grow to around 2 metres (7 ft) long weighing up to 100 kilograms (220 lb), living up to 45 years. The Antarctic toothfish lives close to the Antarctic mainland, whereas the Patagonian toothfish lives in the relatively warmer subantarctic waters. Toothfish are commercially fished, and overfishing has reduced toothfish populations.[126][129]
Another abundant fish group is the genusNotothenia, which like the Antarctic toothfish have antifreeze in their bodies.[126]
An unusual species of icefish is theAntarctic silverfish (Pleuragramma antarcticum), which is the only trulypelagic fish in the waters near Antarctica.[130]
Weddell seals (Leptonychotes weddellii) are the most southerly of Antarctic mammals.
Sevenpinniped species inhabit Antarctica. The largest, theelephant seal (Mirounga leonina), can reach up to 4,000 kilograms (8,818 lb), while females of the smallest, theAntarctic fur seal (Arctophoca gazella), reach only 150 kilograms (331 lb). These two species live north of the sea ice, and breed inharems on beaches. The other four species can live on the sea ice.Crabeater seals (Lobodon carcinophagus) andWeddell seals (Leptonychotes weddellii) form breeding colonies, whereasleopard seals (Hydrurga leptonyx) andRoss seals (Ommatophoca rossii) live solitary lives. Although these species hunt underwater, they breed on land or ice and spend a great deal of time there, as they have no terrestrial predators.[131]
The four species that inhabit sea ice are thought to make up 50% of the total biomass of the world's seals.[132] Crabeater seals have a population of around 15 million, making them one of the most numerous large animals on the planet.[133] TheNew Zealand sea lion (Phocarctos hookeri), one of the rarest and most localised pinnipeds, breeds almost exclusively on the subantarcticAuckland Islands, although historically it had a wider range.[134] Out of all permanent mammalian residents, the Weddell seals live the furthest south.[135]
There are 10cetacean species found in the Southern Ocean: sixbaleen whales, and fourtoothed whales. The largest of these, theblue whale (Balaenoptera musculus), grows to 24 metres (79 ft) long weighing 84 tonnes. Many of these species aremigratory, and travel totropical waters during the Antarctic winter.[136]
Five species ofkrill, small free-swimmingcrustaceans, have been found in the Southern Ocean.[137] TheAntarctic krill (Euphausia superba) is one of the most abundant animal species on earth, with abiomass of around 500 million tonnes. Each individual is 6 centimetres (2.4 in) long and weighs over 1 gram (0.035 oz).[138] The swarms that form can stretch for kilometres, with up to 30,000 individuals per 1 cubic metre (35 cu ft), turning the water red.[137] Swarms usually remain in deep water during the day, ascending during the night to feed onplankton. Many larger animals depend on krill for their own survival.[138] During the winter when food is scarce, adult Antarctic krill can revert to a smaller juvenile stage, using their own body as nutrition.[137]
Many benthic crustaceans have a non-seasonal breeding cycle, and some raise their young in abrood pouch.Glyptonotus antarcticus is an unusually large benthicisopod, reaching 20 centimetres (8 in) in length weighing 70 grams (2.47 oz).Amphipods are abundant in soft sediments, eating a range of items, fromalgae to other animals.[115] The amphipods are highly diverse with more than 600 recognized species found south of the Antarctic Convergence and there are indications that many undescribed species remain. Among these are several "giants", such as the iconicepimeriids that are up to 8 cm (3.1 in) long.[139]
Slow movingsea spiders are common, sometimes growing as large as a human hand. They feed on thecorals,sponges, andbryozoans that litter the seabed.[115]
There are around 70cephalopod species in the Southern Ocean,[140] the largest of which is thecolossal squid (Mesonychoteuthis hamiltoni), which at up to 14 metres (46 ft) is among the largest invertebrate in the world.[141]Squid makes up most of the diet of some animals, such asgrey-headed albatrosses andsperm whales, and thewarty squid (Moroteuthis ingens) is one of the subantarctic's most preyed upon species by vertebrates.[140]
Thesea urchin genusAbatus burrow through the sediment eating the nutrients they find in it.[115] Two species ofsalps are common in Antarctic waters:Salpa thompsoni andIhlea racovitzai.Salpa thompsoni is found in ice-free areas, whereasIhlea racovitzai is found in the high-latitude areas near ice. Due to their low nutritional value, they are normally only eaten by fish, with larger animals such as birds and marine mammals only eating them when other food is scarce.[142]
Antarcticsponges are long-lived and sensitive to environmental changes due to the specificity of thesymbiotic microbial communities within them. As a result, they function as indicators of environmental health.[143]
Increased solarultraviolet radiation resulting from the Antarcticozone hole has reduced marine primary productivity (phytoplankton) by as much as 15% and has started damaging theDNA of some fish.[144]Illegal, unreported and unregulated fishing, especially the landing of an estimated five to six times morePatagonian toothfish than the regulated fishery, likely affects the sustainability of the stock. Long-line fishing for toothfish causes a high incidence of seabird mortality.
An adult and sub-adultMinke whale are dragged aboard the Japanese whaling vesselNisshin Maru.
All international agreements regarding the world's oceans apply to the Southern Ocean. It is also subject to several regional agreements:
TheSouthern Ocean Whale Sanctuary of theInternational Whaling Commission (IWC) prohibits commercialwhaling south of40 degrees south (south of60 degrees south between50 degrees and130 degrees west).Japan regularly does not recognize this provision, because the sanctuary violates IWC charter. Since the scope of the sanctuary is limited to commercial whaling, in regard to its whaling permit and whaling for scientific research, a Japanese fleet carried out an annual whale-hunt in the region. On 31 March 2014, theInternational Court of Justice ruled that Japan's whaling program, which Japan has long claimed is for scientific purposes, was a cloak for commercial whaling, and no further permits would be granted.
Many nations prohibit the exploration for and the exploitation ofmineral resources south of the fluctuatingAntarctic Convergence,[147] which lies in the middle of the Antarctic Circumpolar Current and serves as the dividing line between the very cold polar surface waters to the south and the warmer waters to the north. TheAntarctic Treaty covers the portion of the globe south of60 degrees south;[148] it prohibits new claims to Antarctica.[149]
TheConvention for the Conservation of Antarctic Marine Living Resources applies to the area south of 60° South latitude as well as the areas further north up to the limit of the Antarctic Convergence.[150]
Between 1 July 1998 and 30 June 1999, fisheries landed 119,898tonnes (118,004 long tons; 132,165 short tons), of which 85% consisted ofkrill and 14% ofPatagonian toothfish. International agreements came into force in late 1999 to reduce illegal, unreported, and unregulated fishing, which in the 1998–99 season landed five to six times more Patagonian toothfish than the regulated fishery.
Few ports or harbors exist on the southern (Antarctic) coast of the Southern Ocean, since ice conditions limit use of most shores to short periods in midsummer; even then some requireicebreaker escort for access. Most Antarctic ports are operated by government research stations and, except in an emergency, remain closed to commercial or private vessels; vessels in any port south of60 degrees south are subject to inspection by Antarctic Treaty observers.
Even though organizers of severalyacht races define their routes as involving the Southern Ocean, the actual routes don't enter the actual geographical boundaries of the Southern Ocean. The routes involve insteadSouth Atlantic,South Pacific andIndian Ocean.[152][153][154]
^Also a translation of its former French name (Grand Océan Austral) in reference to its position below thePacific, the "Grand Océan".
^Used byDr. Hooker in his accounts of his Antarctic voyages.[4] Also a translation of the ocean'sJapanese nameNankyoku Kai (南極海).
^Also a translation of the ocean'sChinese nameNánbīng Yáng (南冰洋).
^Historic names include the "South Sea",[2] the "Great Southern Ocean",[3][note 1] the "South Polar Ocean" or "South-Polar Ocean",[note 2] and the "Southern Icy Ocean".[2][note 3]
^Hooker, Joseph Dalton (1843),Flora Antarctica: The Botany of the Antarctic Voyage, London: Reeve
^abcd"Geography – Southern Ocean".CIA Factbook. Retrieved16 July 2012.... the Southern Ocean has the unique distinction of being a large circumpolar body of water totally encircling the continent of Antarctica; this ring of water lies between 60 degrees south latitude and the coast of Antarctica and encompasses 360 degrees of longitude.
^abc"Introduction – Southern Ocean".CIA Factbook. Retrieved16 July 2012....As such, the Southern Ocean is now the fourth largest of the world's five oceans (after the Pacific Ocean, Atlantic Ocean, and Indian Ocean, but larger than the Arctic Ocean).
^Lenton, T. M.; Armstrong McKay, D.I.; Loriani, S.; Abrams, J.F.; Lade, S.J.; Donges, J.F.; Milkoreit, M.; Powell, T.; Smith, S.R.; Zimm, C.; Buxton, J.E.; Daube, Bruce C.; Krummel, Paul B.; Loh, Zoë; Luijkx, Ingrid T. (2023).The Global Tipping Points Report 2023 (Report). University of Exeter.
^Wong, Wilson (10 June 2021)."National Geographic adds 5th ocean to world map".ABC News. NBC Universal. Retrieved11 June 2021.National Geographic announced Tuesday that it is officially recognizing the body of water surrounding the Antarctic as the Earth's fifth ocean: the Southern Ocean.
^"Balboa, or Pan-Pacific Day".The Mid-Pacific Magazine.20 (10).Pan-Pacific Union: 16.He named it the Southern Ocean, but in 1520 Magellan sailed into the Southern Ocean and named it Pacific
^Tomlins, Sir Thomas Edlyne;Raithby, John (1811)."18 George II c. 17".The statutes at large, of England and of Great-Britain: from Magna Carta to the union of the kingdoms of Great Britain and Ireland. Printed by G. Eyre and A. Strahan. p. 153. Retrieved1 November 2015.
^Cook, James (1821)."March 1775".Three Voyages of Captain James Cook Round the World. Longman. p. 244. Retrieved1 November 2015.These voyages of the French, though undertaken by private adventurers, have contributed something toward exploring the Southern Ocean. That of Captain Surville, clears up a mistake, which I was led into, in imagining the shoals off the west end of New Caledonia was to extend to the west, but as far as New Holland.
^Peter Barber, "Ortelius' great world map", National Library of Australia,Mapping our World: Terra Incognita to Australia, Canberra, National Library of Australia, 2013, p. 95.
^Weddel, James (1970) [1825].A voyage towards the South Pole: performed in the years 1822–24, containing an examination of the Antarctic Sea. United States Naval Institute. p. 44.
^abLiu, Y.; Moore, J. K.; Primeau, F.; Wang, W. L. (22 December 2022). "Reduced CO2 uptake and growing nutrient sequestration from slowing overturning circulation".Nature Climate Change.13:83–90.doi:10.1038/s41558-022-01555-7.OSTI2242376.S2CID255028552.
^Marshall, John; Speer, Kevin (26 February 2012). "Closure of the meridional overturning circulation through Southern Ocean upwelling".Nature Geoscience.5 (3):171–180.Bibcode:2012NatGe...5..171M.doi:10.1038/ngeo1391.
^Phiddian, Ellen (5 April 2022)."Explainer: IPCC Scenarios".Cosmos. Retrieved30 September 2023."The IPCC doesn't make projections about which of these scenarios is more likely, but other researchers and modellers can. TheAustralian Academy of Science, for instance, released a report last year stating that our current emissions trajectory had us headed for a 3°C warmer world, roughly in line with the middle scenario.Climate Action Tracker predicts 2.5 to 2.9°C of warming based on current policies and action, with pledges and government agreements taking this to 2.1°C.
^Stewart, K. D.; Hogg, A. McC.; England, M. H.; Waugh, D. W. (2 November 2020). "Response of the Southern Ocean Overturning Circulation to Extreme Southern Annular Mode Conditions".Geophysical Research Letters.47 (22): e2020GL091103.Bibcode:2020GeoRL..4791103S.doi:10.1029/2020GL091103.hdl:1885/274441.S2CID229063736.
^abcLenton, T. M.; Armstrong McKay, D.I.; Loriani, S.; Abrams, J.F.; Lade, S.J.; Donges, J.F.; Milkoreit, M.; Powell, T.; Smith, S.R.; Zimm, C.; Buxton, J.E.; Daube, Bruce C.; Krummel, Paul B.; Loh, Zoë; Luijkx, Ingrid T. (2023).The Global Tipping Points Report 2023 (Report). University of Exeter.
^abcdeAustralian Antarctic Division (12 August 2010)."Seabed (benthic) communities". Government of Australia.Archived from the original on 19 March 2013. Retrieved8 April 2013.
^Uriz, M.J.; J.M. Gili; C. Orejas; A.R. Perez-Porro (2011). "Do bipolar distributions exist in marine sponges? Stylocordyla chupachups sp.nv. (Porifera: Hadromerida) from the Weddell Sea (Antarctic), previously reported as S. borealis (Lovén, 1868)".Polar Biol.34 (2):243–255.Bibcode:2011PoBio..34..243U.doi:10.1007/s00300-010-0876-y.S2CID25074505.
^Australian Antarctic Division (12 August 2010)."Flying Birds". Government of Australia.Archived from the original on 19 March 2013. Retrieved6 April 2013.
^British Antarctic Survey."Land Animals of Antarctica". Natural Environment Research Council. Archived fromthe original on 22 November 2012. Retrieved18 March 2013.
^Australian Antarctic Division."Penguins". Government of Australia.Archived from the original on 19 March 2013. Retrieved6 April 2013.
^Australian Antarctic Division."Adapting to the cold". Government of Australia.Archived from the original on 18 January 2013. Retrieved5 April 2013.
^abcdAustralian Antarctic Division (13 December 2012)."Fish". Government of Australia.Archived from the original on 19 March 2013. Retrieved5 April 2013.
^Jung, A.; P. Johnson; J.T. Eastman; A.L. Devries (1995). "Protein content and freezing avoidance properties of the subdermal extracellular matrix and serum of the Antarctic snailfish, Paraliparis devriesi".Fish Physiol Biochem.14 (1):71–80.Bibcode:1995FPBio..14...71J.doi:10.1007/BF00004292.PMID24197273.S2CID1792885.
^Australian Antarctic Division."Seals and sea lions". Government of Australia.Archived from the original on 19 March 2013. Retrieved8 April 2013.
^Australian Antarctic Division."Pack-ice seal species". Government of Australia.Archived from the original on 26 August 2012. Retrieved8 April 2013.
^Australian Antarctic Division."Salps". Government of Australia.Archived from the original on 19 August 2012. Retrieved8 April 2013.
^Australian Antarctic Division."Sea lions". Government of Australia.Archived from the original on 3 August 2012. Retrieved8 April 2013.
^Australian Antarctic Division."Weddell seals". Government of Australia.Archived from the original on 4 August 2012. Retrieved8 April 2013.
^Australian Antarctic Division (26 April 2012)."What is a whale?". Government of Australia.Archived from the original on 30 May 2012. Retrieved8 April 2013.
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