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129-650: The flotilla was made up of U-boats dispatched from German home ports, which travelled via the Atlantic and the Strait of Gibraltar , and coastal-type UB- and UC-boats , which were moved in segments by rail to Pola and assembled there at the See-Arsenal of the Austro-Hungarian Navy ( kaiserliche und königliche Kriegsmarine : k.u.k.). The Pola Flotilla had a maximum strength of 33 U-boats. Due to

258-492: A World Heritage Site for their geological value, four of them are considered of "Outstanding Universal Value" based on their cultural and natural criteria: Þingvellir , Iceland; Landscape of the Pico Island Vineyard Culture , Portugal; Gough and Inaccessible Islands , United Kingdom; and Brazilian Atlantic Islands: Fernando de Noronha and Atol das Rocas Reserves, Brazil. Continental shelves in

387-506: A Navy Sonic Depth Finder to draw a continuous map across the bed of the Atlantic. This involved little guesswork because the idea of sonar is straightforward with pulses being sent from the vessel, which bounce off the ocean floor, then return to the vessel. The deep ocean floor is thought to be fairly flat with occasional deeps, abyssal plains , trenches , seamounts , basins , plateaus , canyons , and some guyots . Various shelves along

516-721: A branch of the Gulf Stream which flows northward from the Grand Banks ; and the Subpolar Front , an extension of the North Atlantic Current, a wide, vaguely defined region separating the subtropical gyre from the subpolar gyre. This system of currents transports warm water into the North Atlantic, without which temperatures in the North Atlantic and Europe would plunge dramatically. North of

645-527: A few blue-ice areas , the wind and sublimation remove more snow than is accumulated by precipitation. In the dry valleys, the same effect occurs over a rock base, leading to a barren and desiccated landscape. Antarctica is colder than the Arctic region, as much of Antarctica is over 3,000 m (9,800 ft) above sea level, where air temperatures are colder. The relative warmth of the Arctic Ocean

774-523: A land lasted until the European discovery of Australia . During the early 19th century, explorer Matthew Flinders doubted the existence of a detached continent south of Australia (then called New Holland ) and thus advocated for the "Terra Australis" name to be used for Australia instead. In 1824, the colonial authorities in Sydney officially renamed the continent of New Holland to Australia, leaving

903-525: A mild climate. West Antarctica was partially in the Northern Hemisphere , and during the time, large amounts of sandstones , limestones , and shales were deposited. East Antarctica was at the equator, where seafloor invertebrates and trilobites flourished in the tropical seas. By the start of the Devonian period (416  Ma ), Gondwana was in more southern latitudes, and the climate

1032-457: A native bacterial community within the subterranean water body of Lake Vostok . The existence of life there is thought to strengthen the argument for the possibility of life on Jupiter 's moon Europa , which may have water beneath its water-ice crust. There exists a community of extremophile bacteria in the highly alkaline waters of Lake Untersee . The prevalence of highly resilient creatures in such inhospitable areas could further bolster

1161-701: A number of mountain ranges in the region, the most prominent being the Ellsworth Mountains. The presence of the West Antarctic Rift System has resulted in volcanism along the border between West and East Antarctica, as well as the creation of the Transantarctic Mountains. East Antarctica is geologically varied. Its formation began during the Archean Eon (4,000 Ma–2,500 Ma), and stopped during

1290-637: A process described by ice-sheet dynamics . East Antarctica comprises Coats Land , Queen Maud Land , Enderby Land , Mac . Robertson Land , Wilkes Land , and Victoria Land. All but a small portion of the region lies within the Eastern Hemisphere . East Antarctica is largely covered by the East Antarctic Ice Sheet . There are numerous islands surrounding Antarctica, most of which are volcanic and very young by geological standards. The most prominent exceptions to this are

1419-416: A weak Intertropical Convergence Zone , South Atlantic tropical cyclones are rare. The Atlantic Ocean is underlain mostly by dense mafic oceanic crust made up of basalt and gabbro and overlain by fine clay, silt and siliceous ooze on the abyssal plain. The continental margins and continental shelf mark lower density, but greater thickness felsic continental rock that is often much older than that of

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1548-655: Is 1–3 cm (0.39–1.18 in). From the end of the Neoproterozoic era to the Cretaceous , Antarctica was part of the supercontinent Gondwana . Modern Antarctica was formed as Gondwana gradually broke apart beginning around 183 Ma. For a large proportion of the Phanerozoic , Antarctica had a tropical or temperate climate , and it was covered in forests. During the Cambrian period , Gondwana had

1677-621: Is a complex of four water masses, two that form by deep convection in the open ocean – classical and upper Labrador sea water – and two that form from the inflow of dense water across the Greenland-Iceland-Scotland sill – Denmark Strait and Iceland-Scotland overflow water. Along its path across Earth the composition of the NADW is affected by other water masses, especially Antarctic bottom water and Mediterranean overflow water. The NADW

1806-480: Is being revealed by techniques such as remote sensing , ground-penetrating radar , and satellite imagery . Geologically, West Antarctica closely resembles the South American Andes . The Antarctic Peninsula was formed by geologic uplift and the transformation of sea bed sediments into metamorphic rocks . West Antarctica was formed by the merging of several continental plates , which created

1935-449: Is caused by the emission of chlorofluorocarbons and halons into the atmosphere, which causes ozone to break down into other gases. The extreme cold conditions of Antarctica allow polar stratospheric clouds to form. The clouds act as catalysts for chemical reactions, which eventually lead to the destruction of ozone. The 1987 Montreal Protocol has restricted the emissions of ozone-depleting substances. The ozone hole above Antarctica

2064-470: Is evidence of a large number of volcanoes under the ice, which could pose a risk to the ice sheet if activity levels were to rise. The ice dome known as Dome Argus in East Antarctica is the highest Antarctic ice feature, at 4,091 metres (13,422 ft). It is one of the world's coldest and driest places—temperatures there may reach as low as −90 °C (−130 °F), and the annual precipitation

2193-408: Is expected to add about 11 cm (5 in) to global sea level rise . Marine ice sheet instability may cause West Antarctica to contribute tens of centimeters more if it is triggered before 2100. With higher warming, instability would be much more likely, and could double global, 21st-century sea-level rise. The fresh, 1100-1500 billion tons (GT) per year of meltwater from the ice dilutes

2322-467: Is fed by a flow of warm shallow water into the northern North Atlantic which is responsible for the anomalous warm climate in Europe. Changes in the formation of NADW have been linked to global climate changes in the past. Since human-made substances were introduced into the environment, the path of the NADW can be traced throughout its course by measuring tritium and radiocarbon from nuclear weapon tests in

2451-489: Is floating ice in the form of an ice shelf , 38% consists of ice walls that rest on rock, 13% is ice streams or the edge of glaciers, and the remaining 5% is exposed rock. The lakes that lie at the base of the continental ice sheet occur mainly in the McMurdo Dry Valleys or various oases . Lake Vostok , discovered beneath Russia's Vostok Station , is the largest subglacial lake globally and one of

2580-498: Is found off the eastern coast of Canada. Surface water temperatures, which vary with latitude, current systems, and season and reflect the latitudinal distribution of solar energy, range from below −2 °C (28 °F) to over 30 °C (86 °F). Maximum temperatures occur north of the equator, and minimum values are found in the polar regions. In the middle latitudes, the area of maximum temperature variations, values may vary by 7–8 °C (13–14 °F). From October to June

2709-575: Is interrupted by larger transform faults at two places: the Romanche Trench near the Equator and the Gibbs fracture zone at 53°N . The MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other. The MAR rises 2–3 km (1.2–1.9 mi) above the surrounding ocean floor and its rift valley is the divergent boundary between

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2838-854: Is intersected by two perpendicular ridges: the Azores–Gibraltar Transform Fault , the boundary between the Nubian and Eurasian plates , intersects the MAR at the Azores triple junction , on either side of the Azores microplate, near the 40°N . A much vaguer, nameless boundary, between the North American and South American plates, intersects the MAR near or just north of the Fifteen-Twenty fracture zone , approximately at 16°N . In

2967-524: Is mainly a polar desert , with annual precipitation of over 200 mm (8 in) along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost 60 metres (200 ft). Antarctica holds the record for the lowest measured temperature on Earth , −89.2 °C (−128.6 °F). The coastal regions can reach temperatures over 10 °C (50 °F) in

3096-729: Is now northern and central Brazil. The formation of the Central American Isthmus closed the Central American Seaway at the end of the Pliocene 2.8 Ma ago. The formation of the isthmus resulted in the migration and extinction of many land-living animals, known as the Great American Interchange , but the closure of the seaway resulted in a "Great American Schism" as it affected ocean currents, salinity, and temperatures in both

3225-794: Is now the Carpathian region, that were similar to the Sargasso Sea. It is possible that the population in the Sargasso Sea migrated to the Atlantic as the Tethys closed at the end of the Miocene around 17 Ma. The origin of the Sargasso fauna and flora remained enigmatic for centuries. The fossils found in the Carpathians in the mid-20th century often called the "quasi-Sargasso assemblage", finally showed that this assemblage originated in

3354-582: Is predicted to slowly disappear; by the 2060s, levels of ozone are expected to have returned to values last recorded in the 1980s. The ozone depletion can cause a cooling of around 6 °C (11 °F) in the stratosphere . The cooling strengthens the polar vortex and so prevents the outflow of the cold air near the South Pole, which in turn cools the continental mass of the East Antarctic ice sheet. The peripheral areas of Antarctica, especially

3483-504: Is transferred through the Arctic sea ice and moderates temperatures in the Arctic region. East Antarctica is colder than its western counterpart because of its higher elevation. Weather fronts rarely penetrate far into the continent, leaving the centre cold and dry, with moderate wind speeds. Heavy snowfalls are common on the coastal portion of Antarctica, where snowfalls of up to 1.22 m (48 in) in 48 hours have been recorded. At

3612-933: The Iliad and the Odyssey , this all-encompassing ocean was instead known as Oceanus , the gigantic river that encircled the world; in contrast to the enclosed seas well known to the Greeks: the Mediterranean and the Black Sea. In contrast, the term "Atlantic" originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the West African coast. The term " Aethiopian Ocean ", derived from Ancient Ethiopia ,

3741-797: The Age of Discovery , it was known for separating the New World of the Americas ( North America and South America ) from the Old World of Afro-Eurasia ( Africa , Asia , and Europe ). Through its separation of Afro-Eurasia from the Americas, the Atlantic Ocean has played a central role in the development of human society, globalization, and the histories of many nations. While the Norse were

3870-662: The Beardmore Glacier by Frank Wild on the Nimrod Expedition in 1907, and low-grade coal is known to exist across many parts of the Transantarctic Mountains. The Prince Charles Mountains contain deposits of iron ore . There are oil and natural gas fields in the Ross Sea. Antarctica is the coldest, windiest, and driest of Earth's continents. Near the coast, the temperature can exceed 10 °C in summer and fall to below −40 °C in winter. Over

3999-564: The Carpathian Basin from where it migrated over Sicily to the central Atlantic where it evolved into modern species of the Sargasso Sea. The location of the spawning ground for European eels remained unknown for decades . In the early 19th century it was discovered that the southern Sargasso Sea is the spawning ground for both the European and American eel and that the former migrate more than 5,000 km (3,100 mi) and

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4128-610: The Columbian exchange while occasionally hosting naval battles. Such naval battles, as well as growing trade from regional American powers like the United States and Brazil , both increased in degree during the early 20th century, and while no major military conflicts have taken place in the Atlantic recently, the ocean remains a core component of trade around the world. The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to

4257-641: The Cretaceous period (146–66 Ma), though southern beech trees ( Nothofagus ) became prominent towards the end of the Cretaceous. Ammonites were common in the seas around Antarctica, and dinosaurs were also present, though only a few Antarctic dinosaur genera ( Cryolophosaurus and Glacialisaurus , from the Early Jurassic Hanson Formation of the Transantarctic Mountains, and Antarctopelta , Trinisaura , Morrosaurus and Imperobator from Late Cretaceous of

4386-683: The Early Triassic . The Antarctic Peninsula began to form during the Jurassic period ( 206 to 146 million years ago ). Africa separated from Antarctica in the Jurassic around 160 Ma, followed by the Indian subcontinent in the early Cretaceous (about 125 Ma). Ginkgo trees, conifers, Bennettitales , horsetails , ferns and cycads were plentiful during the time. In West Antarctica, coniferous forests dominated throughout

4515-530: The Equator . The oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC (Sch. A. R. 1. 211): Atlantikôi pelágei (Ancient Greek: Ἀτλαντικῷ πελάγει , ' the Atlantic sea ' , etym . ' Sea of Atlas ' ) and in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Ancient Greek: Ἀτλαντὶς θάλασσα , ' Sea of Atlas ' or '

4644-474: The Icelandic Low produces frequent storms. Icebergs are common from early February to the end of July across the shipping lanes near the Grand Banks of Newfoundland . The ice season is longer in the polar regions, but there is little shipping in those areas. Hurricanes are a hazard in the western parts of the North Atlantic during the summer and autumn. Due to a consistently strong wind shear and

4773-684: The North American and Eurasian plates in the North Atlantic and the South American and African plates in the South Atlantic. The MAR produces basaltic volcanoes in Eyjafjallajökull , Iceland, and pillow lava on the ocean floor. The depth of water at the apex of the ridge is less than 2,700 m (1,500 fathoms ; 8,900  ft ) in most places, while the bottom of the ridge is three times as deep. The MAR

4902-616: The North Atlantic Drift is thought to have at least some influence on climate. For example, the Gulf Stream helps moderate winter temperatures along the coastline of southeastern North America, keeping it warmer in winter along the coast than inland areas. The Gulf Stream also keeps extreme temperatures from occurring on the Florida Peninsula. In the higher latitudes, the North Atlantic Drift, warms

5031-514: The North Atlantic oscillation , occurs. On average, the Atlantic is the saltiest major ocean; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand (3.3–3.7%) by mass and varies with latitude and season. Evaporation, precipitation, river inflow and sea ice melting influence surface salinity values. Although the lowest salinity values are just north of the equator (because of heavy tropical rainfall), in general,

5160-582: The Northern Hemisphere , an eventual decline of fisheries in the Southern Ocean and a potential collapse of certain marine ecosystems . While many Antarctic species remain undiscovered, there are documented increases in Antarctic flora , and large fauna such as penguins are already having difficulty retaining suitable habitat. On ice-free land, permafrost thaws release greenhouse gases and formerly frozen pollution. Scientists have studied

5289-662: The Old French pole antartike (modern pôle antarctique ) attested in 1270, and from there the Middle English pol antartik , found first in a treatise written by the English author Geoffrey Chaucer . Belief by Europeans in the existence of a Terra Australis —a vast continent in the far south of the globe to balance the northern lands of Europe, Asia, and North Africa—had existed as an intellectual concept since classical antiquity . The belief in such

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5418-442: The Scotia Sea , and other tributary water bodies. Including these marginal seas the coast line of the Atlantic measures 111,866 km (69,510 mi) compared to 135,663 km (84,297 mi) for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km (41,100,000 sq mi) or 23.5% of the global ocean and has a volume of 310,410,900 km (74,471,500 cu mi) or 23.3% of

5547-401: The Southern Hemisphere climate and Southern Ocean productivity. The name given to the continent originates from the word antarctic , which comes from Middle French antartique or antarctique ('opposite to the Arctic ') and, in turn, the Latin antarcticus ('opposite to the north'). Antarcticus is derived from the Greek ἀντι- ('anti-') and ἀρκτικός ('of

5676-406: The Southern Ocean . Rivers exist in Antarctica; the longest is the Onyx . Antarctica covers more than 14.2 million km (5,500,000 sq mi), almost double the area of Australia, making it the fifth-largest continent, and comparable to the surface area of Pluto . Its coastline is almost 18,000 km (11,200 mi) long: as of 1983 , of the four coastal types, 44% of the coast

5805-428: The Transantarctic Mountains , which stretch from Victoria Land to the Ross Sea . The vast majority of Antarctica is covered by the Antarctic ice sheet , which averages 1.9 km (1.2 mi) in thickness. The ice sheet extends to all but a few oases , which, with the exception of the McMurdo Dry Valleys, are located in coastal areas. Several Antarctic ice streams flow to one of the many Antarctic ice shelves ,

5934-420: The crust-like lichen Buellia frigida , has been used as a model organism in astrobiology research. The same features can be observed in algae and cyanobacteria , suggesting that they are adaptations to the conditions prevailing in Antarctica. This has led to speculation that life on Mars might have been similar to Antarctic fungi, such as Cryomyces antarcticus and Cryomyces minteri . Some of

6063-521: The meridional overturning circulation (MOC), the northward heat transport of which is threatened by anthropogenic climate change. Large variations in the subpolar gyre on a decade-century scale, associated with the North Atlantic oscillation , are especially pronounced in Labrador Sea Water , the upper layers of the MOC. The South Atlantic is dominated by the anti-cyclonic southern subtropical gyre. The South Atlantic Central Water originates in this gyre, while Antarctic Intermediate Water originates in

6192-414: The ozone layer in the atmosphere above Antarctica since the 1970s. In 1985, British scientists, working on data they had gathered at Halley Research Station on the Brunt Ice Shelf , discovered a large area of low ozone concentration over Antarctica. The 'ozone hole' covers almost the whole continent and was at its largest in September 2006; the longest-lasting event occurred in 2020. The depletion

6321-399: The thermocline of the subtropical gyre. The Sargasso Sea in the western North Atlantic can be defined as the area where two species of Sargassum ( S. fluitans and natans ) float, an area 4,000 km (2,500 mi) wide and encircled by the Gulf Stream , North Atlantic Drift , and North Equatorial Current . This population of seaweed probably originated from Tertiary ancestors on

6450-400: The 1870s, the Challenger expedition discovered parts of what is now known as the Mid-Atlantic Ridge, or: An elevated ridge rising to an average height of about 1,900 fathoms [3,500 m; 11,400 ft] below the surface traverses the basins of the North and South Atlantic in a meridianal direction from Cape Farewell, probably its far south at least as Gough Island, following roughly

6579-434: The 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean. The Atlantic has irregular coasts indented by numerous bays, gulfs and seas. These include the Baltic Sea , Black Sea , Caribbean Sea , Davis Strait , Denmark Strait , part of the Drake Passage , Gulf of Mexico , Labrador Sea , Mediterranean Sea , North Sea , Norwegian Sea , almost all of

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6708-408: The 1959 Antarctic Treaty System . According to the terms of the treaty, military activity, mining, nuclear explosions , and nuclear waste disposal are all prohibited in Antarctica. Tourism , fishing and research are the main human activities in and around Antarctica. During the summer months, about 5,000 people reside at research stations , a figure that drops to around 1,000 in the winter. Despite

6837-411: The 1960s and CFCs . The clockwise warm-water North Atlantic Gyre occupies the northern Atlantic, and the counter-clockwise warm-water South Atlantic Gyre appears in the southern Atlantic. In the North Atlantic, surface circulation is dominated by three inter-connected currents: the Gulf Stream which flows north-east from the North American coast at Cape Hatteras ; the North Atlantic Current ,

6966-402: The Antarctic Circle on 17 January 1773, in December 1773, and again in January 1774. Cook came within about 120 km (75 mi) of the Antarctic coast before retreating in the face of field ice in January 1773. In 1775, he called the existence of a polar continent "probable", and in another copy of his journal he wrote: "[I] firmly believe it and it's more than probable that we have seen

7095-526: The Antarctic Peninsula) have been described. During the early Paleogene , Antarctica remained connected to South America as well as to southeastern Australia. Fauna from the La Meseta Formation in the Antarctic Peninsula, dating to the Eocene , is very similar to equivalent South American faunas; with marsupials , xenarthrans , litoptern , and astrapotherian ungulates , as well as gondwanatheres and possibly meridiolestidans . Marsupials are thought to have dispersed into Australia via Antarctica by

7224-423: The Antarctic Peninsula, are then subjected to higher temperatures, which accelerate the melting of the ice. Models suggest that ozone depletion and the enhanced polar vortex effect may also account for the period of increasing sea ice extent, lasting from when observation started in the late 1970s until 2014. Since then, the coverage of Antarctic sea ice has decreased rapidly. Most species in Antarctica seem to be

7353-441: The Antarctic Peninsula: Deschampsia antarctica (Antarctic hair grass), Colobanthus quitensis (Antarctic pearlwort) and the non-native Poa annua (annual bluegrass). Of the 700 species of algae in Antarctica, around half are marine phytoplankton . Multicoloured snow algae are especially abundant in the coastal regions during the summer. Even sea ice can harbour unique ecological communities, as it expels all salt from

7482-426: The Atlantic and Pacific. Marine organisms on both sides of the isthmus became isolated and either diverged or went extinct. Antarctica Antarctica ( / æ n ˈ t ɑːr k t ɪ k ə / ) is Earth 's southernmost and least-populated continent . Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean ), it contains

7611-407: The Atlantic are wide off Newfoundland, southernmost South America, and northeastern Europe. In the western Atlantic carbonate platforms dominate large areas, for example, the Blake Plateau and Bermuda Rise . The Atlantic is surrounded by passive margins except at a few locations where active margins form deep trenches : the Puerto Rico Trench (8,376 m or 27,480 ft maximum depth) in

7740-468: The Atlantic include the Challenger expedition and the German Meteor expedition ; as of 2001 , Columbia University 's Lamont–Doherty Earth Observatory and the United States Navy Hydrographic Office conduct research on the ocean. The MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2,000 m (6,600 ft) along most of its length, but

7869-403: The Atlantic north of the equator. The coldest zones are in high latitudes, with the coldest regions corresponding to the areas covered by sea ice. Ocean currents influence the climate by transporting warm and cold waters to other regions. The winds that are cooled or warmed when blowing over these currents influence adjacent land areas. The Gulf Stream and its northern extension towards Europe,

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7998-455: The Atlantic sea ' ) where the name refers to "the sea beyond the pillars of Heracles " which is said to be part of the sea that surrounds all land. In these uses, the name refers to Atlas , the Titan in Greek mythology , who supported the heavens and who later appeared as a frontispiece in medieval maps and also lent his name to modern atlases . On the other hand, to early Greek sailors and in ancient Greek mythological literature such as

8127-409: The Bahamas, while coarse river outwash sands and silt are common in shallow shelf areas like the Georges Bank . Coarse sand, boulders, and rocks were transported into some areas, such as off the coast of Nova Scotia or the Gulf of Maine during the Pleistocene ice ages. The break-up of Pangaea began in the central Atlantic, between North America and Northwest Africa, where rift basins opened during

8256-412: The Bear ', 'northern'). The Greek philosopher Aristotle wrote in Meteorology about an "Antarctic region" in c.  350 BCE . The Greek geographer Marinus of Tyre reportedly used the name in his world map from the second century CE, now lost. The Roman authors Gaius Julius Hyginus and Apuleius used for the South Pole the romanised Greek name polus antarcticus , from which derived

8385-418: The Cambrian Period. It is built on a craton of rock, which is the basis of the Precambrian Shield . On top of the base are coal and sandstones, limestones, and shales that were laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains. In coastal areas such as the Shackleton Range and Victoria Land, some faulting has occurred. Coal was first recorded in Antarctica near

8514-404: The European shores of the former Tethys Ocean and has, if so, maintained itself by vegetative growth , floating in the ocean for millions of years. Other species endemic to the Sargasso Sea include the sargassum fish , a predator with algae-like appendages which hovers motionless among the Sargassum . Fossils of similar fishes have been found in fossil bays of the former Tethys Ocean, in what

8643-405: The Late Triassic and Early Jurassic. This period also saw the first stages of the uplift of the Atlas Mountains. The exact timing is controversial with estimates ranging from 200 to 170 Ma. The opening of the Atlantic Ocean coincided with the initial break-up of the supercontinent Pangaea , both of which were initiated by the eruption of the Central Atlantic Magmatic Province (CAMP), one of

8772-468: The North Atlantic Gyre, the cyclonic North Atlantic Subpolar Gyre plays a key role in climate variability. It is governed by ocean currents from marginal seas and regional topography, rather than being steered by wind, both in the deep ocean and at sea level. The subpolar gyre forms an important part of the global thermohaline circulation . Its eastern portion includes eddying branches of the North Atlantic Current which transport warm, saline waters from

8901-425: The Pola Flotilla, eleven of which were lost operationally. In June 1917, the unit was renamed U-Flottille Mittelmeer and in January 1918 it was divided into two separate Flotillas, the first based at Pola, and the second at Cattaro, while the commander, re-titled ( Führer der Unterseeboote im Mittelmeer : U-Boat Leader, Mediterranean) assumed overall command of the forces there and at Constantinople . In 1918 at

9030-437: The South Atlantic, and the "Atmospheric Bridge", which evaporates subtropical Atlantic waters and exports it to the Pacific. The Atlantic Ocean consists of four major, upper water masses with distinct temperature and salinity. The Atlantic subarctic upper water in the northernmost North Atlantic is the source for subarctic intermediate water and North Atlantic intermediate water. North Atlantic central water can be divided into

9159-466: The West Antarctic, the ocean has warmed by 1 °C (1.8 °F) since 1955. The warming of the Southern Ocean around Antarctica has caused the weakening or collapse of ice shelves , which float just offshore of glaciers and stabilize them. Many coastal glaciers have been losing mass and retreating, causing net-annual ice loss across Antarctica, although the East Antarctic ice sheet continues to gain ice inland. By 2100, net ice loss from Antarctica

9288-691: The argument for extraterrestrial life in cold, methane -rich environments. The first international agreement to protect Antarctica's biodiversity was adopted in 1964. The overfishing of krill (an animal that plays a large role in the Antarctic ecosystem) led officials to enact regulations on fishing. The Convention for the Conservation of Antarctic Marine Living Resources , an international treaty that came into force in 1980, regulates fisheries, aiming to preserve ecological relationships. Despite these regulations, illegal fishing —particularly of

9417-475: The atmosphere over the oceans, keeping the British Isles and northwestern Europe mild and cloudy, and not severely cold in winter, like other locations at the same high latitude. The cold water currents contribute to heavy fog off the coast of eastern Canada (the Grand Banks of Newfoundland area) and Africa's northwestern coast. In general, winds transport moisture and air over land areas. Every winter,

9546-416: The biodiversity in Antarctica is still at risk from human activities. Specially protected areas cover less than 2% of the area and provide better protection for animals with popular appeal than for less visible animals. There are more terrestrial protected areas than marine protected areas . Ecosystems are impacted by local and global threats, notably pollution , the invasion of non-native species , and

9675-584: The climate cooled, though flora remained. After deglaciation during the latter half of the Early Permian , the land became dominated by glossopterids (an extinct group of seed plants with no close living relatives), most prominently Glossopteris , a tree interpreted as growing in waterlogged soils, which formed extensive coal deposits. Other plants found in Antarctica during the Permian include Cordaitales , sphenopsids , ferns, and lycophytes . At

9804-510: The continent as a World Park . The Southern Ocean Whale Sanctuary was established in 1994 by the International Whaling Commission . It covers 50 million km (19 million sq mi) and completely surrounds the Antarctic continent. All commercial whaling is banned in the zone, though Japan has continued to hunt whales in the area, ostensibly for research purposes. Despite these protections,

9933-599: The continent's edge, strong katabatic winds off of the polar plateau often blow at storm force . During the summer, more solar radiation reaches the surface at the South Pole than at the equator because of the 24 hours of sunlight received there each day. Climate change caused by greenhouse gas emissions from human activities occurs everywhere on Earth, and while Antarctica is less vulnerable to it than any other continent, climate change in Antarctica has been observed. Since 1959, there has been an average temperature increase of >0.05 °C/decade since 1957 across

10062-471: The continent's remoteness, human activity has a significant effect on it via pollution , ozone depletion , and climate change . The melting of the potentially unstable West Antarctic ice sheet causes the most uncertainty in century-scale projections of sea level rise , and the same melting also affects the Southern Ocean overturning circulation , which can eventually lead to significant impacts on

10191-496: The continent, although it had been uneven. West Antarctica warmed by over 0.1 °C/decade from the 1950s to the 2000s, and the exposed Antarctic Peninsula has warmed by 3 °C (5.4 °F) since the mid-20th century. The colder, stabler East Antarctica had been experiencing cooling until the 2000s. Around Antarctica, the Southern Ocean has absorbed more oceanic heat than any other ocean, and has seen strong warming at depths below 2,000 m (6,600 ft). Around

10320-402: The creation of small yet permanent polar ice caps. As CO 2 levels declined further the ice began to spread rapidly, replacing the forests that until then had covered Antarctica. Tundra ecosystems continued to exist on Antarctica until around 14-10 million years ago, when further cooling lead to their extermination. The geology of Antarctica, largely obscured by the continental ice sheet,

10449-549: The descendants of species that lived there millions of years ago. As such, they must have survived multiple glacial cycles . The species survived the periods of extremely cold climate in isolated warmer areas , such as those with geothermal heat or areas that remained ice-free throughout the colder climate. Invertebrate life of Antarctica includes species of microscopic mites such as Alaskozetes antarcticus , lice , nematodes , tardigrades , rotifers , krill and springtails . The few terrestrial invertebrates are limited to

10578-582: The early Eocene. Around 53 Ma, Australia- New Guinea separated from Antarctica, opening the Tasmanian Passage . The Drake Passage opened between Antarctica and South America around 30 Ma, resulting in the creation of the Antarctic Circumpolar Current that completely isolated the continent. Models of Antarctic geography suggest that this current, as well as a feedback loop caused by lowering CO 2 levels, caused

10707-547: The east, and the Americas to the west. As one component of the interconnected World Ocean , it is connected in the north to the Arctic Ocean , to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south. Other definitions describe the Atlantic as extending southward to Antarctica . The Atlantic Ocean is divided in two parts, the northern and southern Atlantic, by

10836-615: The east, the boundaries of the ocean proper are Europe: the Strait of Gibraltar (where it connects with the Mediterranean Sea  – one of its marginal seas  – and, in turn, the Black Sea , both of which also touch upon Asia) and Africa. In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian , running south from Cape Agulhas to Antarctica defines its border. In

10965-544: The eastern and western North Atlantic central water since the western part is strongly affected by the Gulf Stream and therefore the upper layer is closer to underlying fresher subpolar intermediate water. The eastern water is saltier because of its proximity to Mediterranean water. North Atlantic central water flows into South Atlantic central water at 15°N . There are five intermediate waters: four low-salinity waters formed at subpolar latitudes and one high-salinity formed through evaporation. Arctic intermediate water flows from

11094-489: The elevated inland, it can rise to about −30 °C in summer but fall below −80 °C in winter. The lowest natural air temperature ever recorded on Earth was −89.2 °C (−128.6 °F) at the Russian Vostok Station in Antarctica on 21 July 1983. A lower air temperature of −94.7 °C (−138.5 °F) was recorded in 2010 by satellite—however, it may have been influenced by ground temperatures and

11223-553: The end of that period. During the colder Neogene (17–2.5 Ma), a tundra ecosystem replaced the rainforests. The climate of present-day Antarctica does not allow extensive vegetation to form. A combination of freezing temperatures, poor soil quality , and a lack of moisture and sunlight inhibit plant growth, causing low species diversity and limited distribution. The flora largely consists of bryophytes (25 species of liverworts and 100 species of mosses ). There are three species of flowering plants , all of which are found in

11352-587: The end of the Permian, the climate became drier and hotter over much of Gondwana, and the glossopterid forest ecosystems collapsed, as part of the End-Permian mass extinction . There is no evidence of any tetrapods having lived in Antarctica during the Paleozoic. The continued warming dried out much of Gondwana. During the Triassic, Antarctica was dominated by seed ferns (pteridosperms) belonging to

11481-684: The end of the campaign, the Pola Flotilla was evacuated to Germany. One of its boats, SM  UB-50 sank the battleship HMS  Britannia , the last British warship sunk during the U-Boat Campaign in World War I. Atlantic The Atlantic Ocean is the second-largest of the world's five oceanic divisions , with an area of about 85,133,000 km (32,870,000 sq mi). It covers approximately 17% of Earth's surface and about 24% of its water surface area. During

11610-627: The favourable conditions for commerce raiding in the Mediterranean, they caused a disproportionately large number of Allied losses during the U-boat campaign. 3.6 million tons of the 14 million tons lost by the Allies were sunk in the Mediterranean. Eight of the IGN's top dozen U-boat aces served in the Pola flotilla, including Lothar von Arnauld de la Perière and Waldemar Kophamel . In all, 45 U-boats served in

11739-493: The first known humans to cross the Atlantic, it was the expedition of Christopher Columbus in 1492 that proved to be the most consequential. Columbus' expedition ushered in an age of exploration and colonization of the Americas by European powers , most notably Portugal , Spain , France , and the United Kingdom . From the 16th to 19th centuries, the Atlantic Ocean was the center of both an eponymous slave trade and

11868-402: The gap of 12,000 km (7,456 mi). Large animals such as some cetaceans and birds make the round trip annually. Smaller forms of life, such as sea cucumbers and free-swimming snails , are also found in both polar oceans. Factors that may aid in their distribution include temperature differences between the deep ocean at the poles and the equator of no more than 5 °C (9 °F) and

11997-502: The genus Dicroidium , which grew as trees. Other associated Triassic flora included ginkgophytes , cycadophytes , conifers , and sphenopsids. Tetrapods first appeared in Antarctica during the early Triassic , with the earliest known fossils found in the Fremouw Formation of the Transantarctic Mountains. Synapsids (also known as "mammal-like reptiles") included species such as Lystrosaurus , and were common during

12126-422: The geographic South Pole . Antarctica is the fifth-largest continent, being about 40% larger than Europe , and has an area of 14,200,000 km (5,500,000 sq mi). Most of Antarctica is covered by the Antarctic ice sheet , with an average thickness of 1.9 km (1.2 mi). Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation . It

12255-519: The highly prized Patagonian toothfish which is marketed as Chilean sea bass in the U.S.—remains a problem. In analogy to the 1980 treaty on sustainable fishing , countries led by New Zealand and the United States negotiated a treaty on mining. This Convention on the Regulation of Antarctic Mineral Resource Activities was adopted in 1988. After a strong campaign from environmental organisations, first Australia and then France decided not to ratify

12384-553: The islands of the Kerguelen Plateau , the earliest of which formed around 40 Ma . Vinson Massif , in the Ellsworth Mountains , is the highest peak in Antarctica at 4,892 m (16,050 ft). Mount Erebus on Ross Island is the world's southernmost active volcano and erupts around 10 times each day. Ash from eruptions has been found 300 kilometres (190 mi) from the volcanic crater . There

12513-447: The largest lakes in the world. It was once believed that the lake had been sealed off for millions of years, but scientists now estimate its water is replaced by the slow melting and freezing of ice caps every 13,000 years. During the summer, the ice at the edges of the lakes can melt, and liquid moats temporarily form. Antarctica has both saline and freshwater lakes. Antarctica is divided into West Antarctica and East Antarctica by

12642-517: The latter 2,000 km (1,200 mi). Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and northern Africa. Recent but disputed research suggests that eels possibly use Earth's magnetic field to navigate through the ocean both as larvae and as adults. The climate is influenced by the temperatures of the surface waters and water currents as well as winds. Because of

12771-666: The limits of the oceans and seas in 1953, but some of these definitions have been revised since then and some are not recognized by various authorities, institutions, and countries, for example the CIA World Factbook . Correspondingly, the extent and number of oceans and seas vary. The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait , Greenland Sea , Norwegian Sea and Barents Sea . To

12900-501: The lowest values are in the high latitudes and along coasts where large rivers enter. Maximum salinity values occur at about 25° north and south , in subtropical regions with low rainfall and high evaporation. The high surface salinity in the Atlantic, on which the Atlantic thermohaline circulation is dependent, is maintained by two processes: the Agulhas Leakage/Rings , which brings salty Indian Ocean waters into

13029-885: The major current systems or marine conveyor belts which are able to transport eggs and larva . About 1,150 species of fungi have been recorded in the Antarctic region, of which about 750 are non- lichen -forming. Some of the species, having evolved under extreme conditions, have colonised structural cavities within porous rocks and have contributed to shaping the rock formations of the McMurdo Dry Valleys and surrounding mountain ridges. The simplified morphology of such fungi, along with their similar biological structures , metabolism systems capable of remaining active at very low temperatures, and reduced life cycles, make them well suited to such environments. Their thick-walled and strongly melanised cells make them resistant to UV radiation. An Antarctic endemic species,

13158-514: The margins of the continents constitute about 11% of the bottom topography with few deep channels cut across the continental rise. The mean depth between 60°N and 60°S is 3,730 m (12,240 ft), or close to the average for the global ocean, with a modal depth between 4,000 and 5,000 m (13,000 and 16,000 ft). In the South Atlantic the Walvis Ridge and Rio Grande Rise form barriers to ocean currents. The Laurentian Abyss

13287-664: The maximum depth, the Milwaukee Deep in the Puerto Rico Trench , is 8,376 m (27,480 ft). Top large seas: The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge (MAR). It runs from 87°N or 300 km (190 mi) south of the North Pole to the subantarctic Bouvet Island at 54°S . Expeditions to explore the bathymertry of

13416-471: The moniker Great White South , after which British photographer Herbert Ponting named one of his books on Antarctic photography, possibly as a counterpart to the epithet Great White North for Canada . Positioned asymmetrically around the South Pole and largely south of the Antarctic Circle (one of the five major circles of latitude that mark maps of the world), Antarctica is surrounded by

13545-732: The most extensive and voluminous large igneous provinces in Earth's history associated with the Triassic–Jurassic extinction event , one of Earth's major extinction events . Theoliitic dikes , sills , and lava flows from the CAMP eruption at 200 Ma have been found in West Africa, eastern North America, and northern South America. The extent of the volcanism has been estimated to 4.5 × 10  km (1.7 × 10  sq mi) of which 2.5 × 10  km (9.7 × 10  sq mi) covered what

13674-571: The north to become the source for North Atlantic deep water, south of the Greenland-Scotland sill. These two intermediate waters have different salinity in the western and eastern basins. The wide range of salinities in the North Atlantic is caused by the asymmetry of the northern subtropical gyre and a large number of contributions from a wide range of sources: Labrador Sea, Norwegian-Greenland Sea, Mediterranean, and South Atlantic Intermediate Water. The North Atlantic deep water (NADW)

13803-578: The ocean around Antarctica, including some that normally reside in the Arctic. The emperor penguin is the only penguin that breeds during the winter in Antarctica; it and the Adélie penguin breed farther south than any other penguin. A Census of Marine Life by some 500 researchers during the International Polar Year was released in 2010. The research found that more than 235 marine organisms live in both polar regions, having bridged

13932-425: The ocean's great capacity to store and release heat, maritime climates are more moderate and have less extreme seasonal variations than inland climates. Precipitation can be approximated from coastal weather data and air temperature from water temperatures. The oceans are the major source of atmospheric moisture that is obtained through evaporation. Climatic zones vary with latitude; the warmest zones stretch across

14061-627: The outlines of the coasts of the Old and the New Worlds. The remainder of the ridge was discovered in the 1920s by the German Meteor expedition using echo-sounding equipment. The exploration of the MAR in the 1950s led to the general acceptance of seafloor spreading and plate tectonics . Most of the MAR runs under water but where it reaches the surfaces it has produced volcanic islands. While nine of these have collectively been nominated

14190-651: The pond" or "on the other side of the pond" or "across the pond", rather than to discuss the ocean itself. The term dates to 1640, first appearing in print in a pamphlet released during the reign of Charles I , and reproduced in 1869 in Nehemiah Wallington 's Historical Notices of Events Occurring Chiefly in The Reign of Charles I , where "great Pond" is used in reference to the Atlantic Ocean by Francis Windebank , Charles I's Secretary of State . The International Hydrographic Organization (IHO) defined

14319-539: The saline Antarctic bottom water , weakening the lower cell of the Southern Ocean overturning circulation (SOOC). According to some research, a full collapse of the SOOC may occur a between 1.7 °C (3.1 °F) and 3 °C (5.4 °F) of global warming, although the full effects are expected to occur over multiple centuries; these include less precipitation in the Southern Hemisphere but more in

14448-438: The seafloor. The oldest oceanic crust in the Atlantic is up to 145 million years and is situated off the west coast of Africa and the east coast of North America, or on either side of the South Atlantic. In many places, the continental shelf and continental slope are covered in thick sedimentary layers. For instance, on the North American side of the ocean, large carbonate deposits formed in warm shallow waters such as Florida and

14577-406: The species of fungi, which are apparently endemic to Antarctica, live in bird dung, and have evolved so they can grow inside extremely cold dung, but can also pass through the intestines of warm-blooded animals. Throughout its history, Antarctica has seen a wide variety of plant life. In the Cretaceous , it was dominated by a fern- conifer ecosystem, which changed into a temperate rainforest by

14706-683: The sub-Antarctic islands. The flightless midge Belgica antarctica , the largest purely terrestrial animal in Antarctica, reaches 6 mm ( 1 ⁄ 4  in) in size. Antarctic krill , which congregates in large schools , is the keystone species of the ecosystem of the Southern Ocean, being an important food organism for whales, seals, leopard seals , fur seals, squid , icefish , and many bird species, such as penguins and albatrosses . Some species of marine animals exist and rely, directly or indirectly, on phytoplankton . Antarctic sea life includes penguins , blue whales , orcas , colossal squids and fur seals . The Antarctic fur seal

14835-551: The subtropics to the northeastern Atlantic. There this water is cooled during winter and forms return currents that merge along the eastern continental slope of Greenland where they form an intense (40–50  Sv ) current which flows around the continental margins of the Labrador Sea . A third of this water becomes part of the deep portion of the North Atlantic Deep Water (NADW). The NADW, in turn, feeds

14964-474: The summer. Native species of animals include mites , nematodes , penguins , seals and tardigrades . Where vegetation occurs, it is mostly in the form of lichen or moss . The ice shelves of Antarctica were probably first seen in 1820, during a Russian expedition led by Fabian Gottlieb von Bellingshausen and Mikhail Lazarev . The decades that followed saw further exploration by French, American, and British expeditions. The first confirmed landing

15093-421: The surface is usually covered with sea ice in the Labrador Sea , Denmark Strait , and Baltic Sea. The Coriolis effect circulates North Atlantic water in a clockwise direction, whereas South Atlantic water circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal; that is, two high tides occur every 24 lunar hours. In latitudes above 40° North some east–west oscillation, known as

15222-562: The term "Terra Australis" unavailable as a reference to Antarctica. Over the following decades, geographers used phrases such as "the Antarctic Continent". They searched for a more poetic replacement, suggesting names such as Ultima and Antipodea . Antarctica was adopted in the 1890s, with the first use of the name being attributed to the Scottish cartographer John George Bartholomew . Antarctica has also been known by

15351-428: The total volume of the Earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km (31,570,000 sq mi) and has a volume of 305,811,900 km (73,368,200 cu mi). The North Atlantic covers 41,490,000 km (16,020,000 sq mi) (11.5%) and the South Atlantic 40,270,000 km (15,550,000 sq mi) (11.1%). The average depth is 3,646 m (11,962 ft) and

15480-592: The treaty. Instead, countries adopted the Protocol on Environmental Protection to the Antarctic Treaty (the Madrid Protocol), which entered into force in 1998. The Madrid Protocol bans all mining, designating the continent as a "natural reserve devoted to peace and science". The pressure group Greenpeace established a base on Ross Island from 1987 to 1992 as part of its attempt to establish

15609-637: The upper layers of the circumpolar region, near the Drake Passage and the Falkland Islands. Both these currents receive some contribution from the Indian Ocean. On the African east coast, the small cyclonic Angola Gyre lies embedded in the large subtropical gyre. The southern subtropical gyre is partly masked by a wind-induced Ekman layer . The residence time of the gyre is 4.4–8.5 years. North Atlantic Deep Water flows southward below

15738-470: The various effects of climate change . Early world maps, like the 1513 Piri Reis map , feature the hypothetical continent Terra Australis . Much larger than and unrelated to Antarctica, Terra Australis was a landmass that classical scholars presumed necessary to balance the known lands in the northern hemisphere. Captain James Cook 's ships, HMS  Resolution and Adventure , crossed

15867-412: The water when it freezes, which accumulates into pockets of brine that also harbour dormant microorganisms. When the ice begins to melt, brine pockets expand and can combine to form brine channels, and the algae inside the pockets can reawaken and thrive until the next freeze. Bacteria have also been found as deep as 800 m (0.50 mi) under the ice. It is thought to be likely that there exists

15996-424: The western Atlantic and South Sandwich Trench (8,264 m or 27,113 ft) in the South Atlantic. There are numerous submarine canyons off northeastern North America, western Europe, and northwestern Africa. Some of these canyons extend along the continental rises and farther into the abyssal plains as deep-sea channels. In 1922, a historic moment in cartography and oceanography occurred. The USS Stewart used

16125-494: Was applied to the southern Atlantic as late as the mid-19th century. During the Age of Discovery , the Atlantic was also known to English cartographers as the Great Western Ocean . The pond is a term often used by British and American speakers in reference to the northern Atlantic Ocean, as a form of meiosis , or ironic understatement. It is used mostly when referring to events or circumstances "on this side of

16254-428: Was by a Norwegian team in 1895. In the early 20th century, there were a few expeditions into the interior of the continent. British explorers Robert Falcon Scott and Ernest Shackleton were the first to reach the magnetic South Pole in 1909, and the geographic South Pole was first reached in 1911 by Norwegian explorer Roald Amundsen . Antarctica is governed by about 30 countries , all of which are parties of

16383-585: Was cooler, though fossils of land plants are known from then. Sand and silts were laid down in what is now the Ellsworth, Horlick , and Pensacola Mountains . Antarctica became glaciated during the Late Paleozoic icehouse beginning at the end of the Devonian period (360 Ma), though glaciation would substantially increase during the late Carboniferous . It drifted closer to the South Pole, and

16512-472: Was not recorded at a height of 2 m (7 ft) above the surface as required for official air temperature records. Antarctica is a polar desert with little precipitation ; the continent receives an average equivalent to about 150 mm (6 in) of water per year, mostly in the form of snow. The interior is dryer and receives less than 50 mm (2 in) per year, whereas the coastal regions typically receive more than 200 mm (8 in). In

16641-503: Was very heavily hunted in the 18th and 19th centuries for its pelt by seal hunters from the United States and the United Kingdom. Leopard seals are apex predators in the Antarctic ecosystem and migrate across the Southern Ocean in search of food. There are approximately 40 bird species that breed on or close to Antarctica, including species of petrels , penguins , cormorants , and gulls . Various other bird species visit

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