Antarctica is the southernmost continent on Earth, located in the Antarctic region of the Southern Hemisphere and home to the astronomical Antarctica. Most of Antarctica is within the Antarctic Circle, surrounded by the Southern Ocean. Antarctica is the fifth largest continent in the world, with an area of about 14 million square kilometers, accounting for one-tenth of the Earth's land and air footprint, after Asia, Africa, North and South America, and twice as large as Oceania. With the exception of the northernmost part of the Antarctic Peninsula, about 98% of the continent is obscured by ice with a uniform thickness of 1.9 km [2].
Antarctica is the coldest, boring and windy continent on Earth, the only continent that straddles all meridians [3], with an average altitude of 2350 meters, the highest uniform altitude in the world, the whole territory is covered by ice and snow, accounting for more than 80% of the earth's ice sheet. It receives only 200 mm of annual precipitation along the coast and even less inland [4]. The uniform temperature in Antarctica is as low as -63°C during the coldest time of the year, with an observed minimum temperature of -89.2°C in 1983. Antarctica's native species include algae, bacteria, fungi, plants (including mosses), protists, and animals that adapt to cold environments such as penguins, seals, nematodes, tardigrades, mites, etc. Antarctica has no permanent inhabitants, but between 1,000 and 5,000 researchers live here every year.
Although there were myths and conjectures about the "unknown southern continent" (Latin: Terra Australis) a long time ago, it was not until 1820, when Russian explorers Mikhail Lazarev and Fabian Gottlieb von Bellingsgaujin came to the Finbull Ice Shelf on the warships Vostok and War, that humans first witnessed it. Due to its harsh climate, lack of resources and astronomical isolation, Antarctica did not attract attention in the nineteenth century.
Antarctica is now a de jure condominium territory, governed by consultation among the member states of the Antarctic Treaty System. In 1959, 12 countries signed the Antarctic Treaty, followed by 38 countries. The Treaty is intended to support scientific research and the maintenance of the Antarctic Bioastronomical Dispersal Zone and to halt all military activities, nuclear explosive experiments and the disposal of radioactive materials in Antarctica. As of 2016, Antarctica has 135 permanent scientific research stations, which have attracted more than 4,000 scientists from all over the world to stop scientific experiments.
Adélie penguins in Antarctica.
The English title "Antarctica" is derived from the Romanized Greek feminine compound word "antarktiké" (Greek: ἀνταρκτική), meaning "opposite the North Pole".
Around 350 BC, Aristotle mentioned the "Antarctic region" in his book The Theory of Celestial Phenomena.[8] It is said that in the second century AD, Malinass of Tyre (present-day Lebanon) used this title in his world map. The ancient Roman writers Xuchenus and Apulius (1–2nd century AD) used the Romanized Greek word "polus antarcticus" to describe the South Pole.[9][10] The Old French word "pole antartike" (modern French "pôle antarctique") was proved to have originated from this in 1270. The Middle English derivative of the word, "pol antartik" ("Antarctic Pole" in modern English), was first presented in a scientific paper written by Geoffrey Chaucer in 1391.[11]
Before being given a truly astronomical significance, these terms were often used to describe the South in a broad sense.[12] For example, in the sixteenth century, the short-term French colony in Brazil was called "France Antarctique", or "French Southern Territory".
In 1890, Scottish cartographer John George Bartholomew made the term "Antarctica" the official astronomical term for Antarctica.
Astronomical
stratified color map
of Antarctica Antarctica is the southernmost continent on Earth, mostly located in the Antarctic Circle, surrounded by the Southern Ocean, beyond which is the southern part of the Stable Ocean, the Atlantic Ocean and the Indian Ocean, and is also located in the southernmost part of the World Ocean. Antarctica covers an area of more than 14 million square kilometers[1], about 30% more than Europe, and is the fifth largest continent in the world. The coastline of Antarctica is 17,968 km long[1], and its main features are closely related to the appearance of ice, as shown in the following table:
Antarctica coast type[15]
Type Proportion
of ice shelter 44% ice wall 38%
ice flow, glacier injection 13
Rocky shore 5% total 100%
Antarctica is 98%
covered by ice sheets, with ice uniform thickness of at least 1.6 km. Antarctica is home to about 90% of the world's ice and 70% of its fresh water, and if all of this ice melts, sea levels would rise by about 60 metres [16]. In the interior of Antarctica, precipitation in large areas is very small, with annual precipitation of only 20mm. However, in a few blue ice shed areas, precipitation is less than evaporation, so that the local ice is gradually reduced. The McMurdo Valley is an extremely boring center, and it is also the only center in Antarctica that is not covered by ice and snow, showing a desert shape. [17]
Topographic
main articles: List of Antarctic peaks and List of Antarctic volcanoes
View from Cape Harrett to Mount Herschel (3335 m above sea level)
See also: List of
islands around Antarctica The marginal seas of Antarctica include the Bellingsgaugin Sea, the Ross Sea, the Amundsen Sea, which belongs to the South Atlantic Ocean, and the Weddell Sea, which belongs to the South Atlantic. The main islands are Auckland Islands, Bouvet Islands, South Shetland Islands, South Orkney Islands, Adelaide, Alexandria, Peter I Island, South Georgia, Prince Edward Islands, and South Sandwich Islands. [18] [19]
The topography of the Antarctic continent can be divided into two types: one is the visible terrain composed of rocks and ice exposed to the surface, and the other is the subglacial bedrock terrain measured by seismic technology or remote sensing technology. The Trans-Antarctic Mountain Range near the Ross Sea and the Weddell Sea divides Antarctica into two parts, East Antarctica and West Antarctica, which roughly runs parallel to the Greenwich Meridian and is more than 3,000 kilometers long.
The Antarctic Canyon is the largest canyon in the world, located in Antarctica's Princess Elizabeth Land, with a length of about 1,000 kilometers, with some central depths of up to 1,000 meters. [20]
The part west of the Weddell Sea and east of the Ross Sea is West Antarctica; The rest of the region is East Antarctica, which accounts for most of the entire Antarctica. [21] West Antarctica is covered by the West Antarctic ice sheet. In recent years, there has been great concern about the state of the West Antarctic ice sheet, which will cause sea level rise due to its occasional collapse. About 10% of the ice sheet turns into ice streams and travels to the coast to form ice sheets. [22] East Antarctica is a part of the Indian Ocean and the Trans-Antarctic Mountains, most of which is located in the Eastern Hemisphere and consists of Coatesland, Queen Maud Land, Enderbye Land, MacRobertson Land, Wilkes Land, and Victoria Land. East Antarctica is mainly covered by the East Antarctic ice sheet. [23]
Mount Vincennes is the highest mountain in Antarctica, reaching a height of 4892 meters and belongs to the Ellsworth Mountains. Antarctica has many peaks that lie on the continent of Antarctica and surrounding islands. Mount Eripers on Ross Island is the southernmost active volcano in the world. Another well-known volcano is located on Scam Island, which attracted worldwide attention for its eruption in 1970. In addition, other dormant volcanoes in Antarctica may reactivate [24]. In 2004, a potentially active underwater volcano on the Antarctic Peninsula was discovered by scientists in the United States and Canada [25].
Antarctica Mountain
Range Designation Highest Elevation Illustrate Map
Allardyce Mountains 2,934 m South Georgia and the South Sandwich Islands Antarctica.svg
Tengger Mountains 1,700 m Livingston Island
Queen Maud Mountains 4,068 m Part of the Trans-Antarctic Mountain Range including the Bush Mountains, the Commonwealth Mountains, the Dominion Mountains, the Gothic Mountains, the Herbert Mountains, the Prince Olaf Mountains, the Hughes Mountains, the Supporter Mountains The Admeralty Mountains 4,165 m It is part of the Trans-Antarctic Mountains
.
Black Mai-Fronte Mountains 2,711 m Queen Maud Landsa
Pensacola Mountains 2,150 m The
Salveson Mountains, part of the Trans-Antarctic Mountains 2,330 m Ellsworth Mountains, South Georgia and the South Sandwich Islands
4,892 m Mount Vincennes, the highest mountain range in Antarctica, the highest peak.
Gamburzev Mountains 3,500 m Near the left of the Ice Dome A in East Antarctica[26]
During the
polar day, the warmer areas of the Antarctic coast will have ice and snow melting, and the melting snow water will accumulate into some trickles. The largest river on the Antarctic continent is the Onyx River at White Rock in East Antarctica. On the islands surrounding the mainland, summer snow and ice water can also gather into seasonal seasonal streams that flow into the sea. No matter which part of the Antarctic you are in, when winter comes, all the rivers disappear. [27]
There are numerous lakes on the Antarctic continent, ranging from freshwater to saltwater (salt lakes). Freshwater lakes are scattered along the edges of the Antarctic continent. Another saltwater lake is unique to the Antarctic continent, such as Lake Vantaa in Wright in Victoria and Lake Bonny in Taylor Valley.[28] Its characteristics are that the lake water is light and salty, the lake surface is frozen with a layer of 2~3 meters thick ice, the salt content of the lake water increases with the increase of depth, constituting a layered phenomenon, and the salt content of the bottom water is about 10 times higher than that of the surface water; The temperature of the lake also increases with depth, and the temperature at the bottom of the lake is still as high as 25°C in an environment with an average annual temperature of minus 20 degrees.
There are about 70 large subglacial lakes under the East Antarctic continental ice sheet, with a total area estimated at 14,000 square kilometers, and constitute intact freshwater ecosystems [29]. In 1966, Vostok Lake (Lake Vostochny) was discovered under the Vostok station in Russia, covering an area of about 8,000 square kilometers and an ice sheet thickness of 4 kilometers. It is the largest subglacial lake ever discovered. It was thought that these lakes had been frozen in ice for half a million to a million years. However, the latest study shows that every once in a while, a large amount of water moves between different lakes. [30] Evidence of ice cores drilled 400 m above the waterline suggests the presence of microorganisms in the waters of Lake Vostok. The frozen lake is similar in nature to Europa, and if there is life in the lake, it is clear that there may also be life on Europa.[31][32] On February 7, 2008, a NASA team went to Lake Wintersay to conduct a study in an attempt to find basophils living in highly alkaline water, which, if found, would provide evidence for extraterrestrial organisms to survive in extremely cold and methane-rich environments [33]. Subsequent studies have also indicated that there are indeed new species, such as the strain UL7-96mG [34].
The climate
is located in the Transantarctic Mountains, and Lake Fricksell is hidden by blue ice. The glaciers in Lake Fricksell are formed by the confluence of glacial meltwater from glaciers in Canada and other Xiaoice rivers and solidified.
Coastal areas in December look mild, and Antarctica is the coldest continent on Earth,
with average annual temperatures of −25 °C (−13.0 °F), inland winters can reach temperatures below −80 °C (−112 °F), and coastal summer temperatures are around 5 °C (41 °F) to 15 °C (59 °F). On July 21, 1983, the Soviet Vostok station in Antarctica measured a low temperature of −89.2 °C (−128.6 °F). This is the lowest temperature recorded in aerial observatories since the dawn of human climate records [35]. This temperature is lower than the temperature at which dry ice sublimates at one atmosphere (−78.5 °C (−109.3 °F))[a]. Satellite observations suggest that the extreme value of the minimum winter temperature in Antarctica may be lower than this recorded value [36]. Antarctica is a frozen desert with very little rainfall, with an average annual precipitation of less than 200 mm [37].
The snow surface of Ice Dome C is similar to that of the rest of the Antarctic continent.
Affected by the topography of the plateau, the edge of the Antarctic continent is often hit by the intense landing winds from the Antarctic plateau, and there are often no strong winds in the interior of the continent. The year-round falling winds rarely allow hot and humid air currents to enter the interior of Antarctica, which forms a cold and boring central continent [b], while the coastal area is relatively mild and humid: the annual uniform temperature in the inland area of Antarctica is −40 °C (−40 °F) to −50 °C (−58 °F), and the annual precipitation is only about 30 mm, but there is almost no precipitation near the pole; The coastal region has a uniform annual temperature of −17 °C (1 °F) to −20 °C (−4 °F) and frequent heavy snowfall, with annual precipitation reaching about 500 mm and a record of 1.22 m in 48 hours. In addition, due to the high altitude of East Antarctica, the climate is much colder than in the west. [1] [38]
There are three factors that make Antarctica colder than the Arctic: first, the local area of Antarctica is above 3,000 meters above sea level, and the entire Arctic region is almost to the left of sea level[c]; Second, most of the Arctic region is the Arctic Ocean, while most of the Antarctic region is land. Because the land has less specific heat, warming and cooling are faster than that, and Antarctica cools faster at night; Third, the Earth reaches aphelion in July and perihelion in January[d], and variations in the Sun-Earth interval expose Antarctica to less radiation in winter than to the Arctic during winter. The first two are the primary causes and the latter are the secondary causes. [39]
The Antarctic continent is covered by snow and ice throughout the year, which results in a very high albedo in the Antarctic region. Since the snow reflects almost all ultraviolet rays, sunburn and cataracts are common well-being problems in Antarctica [37]. Antarctica is located in high latitudes and has long polar days and nights, which are quite unfamiliar to people living in other centers. On clear summer days, the density of solar radiation in the uniform solar radiation is greater than in the equatorial region due to the sunshine of the Antarctic continent 24 hours a day. The night sky near the left of Antarctica sometimes shows the aurora aurora[e]. A cloud of micro Xiaoice crystals made of microcrystals is sometimes seen near the left of the Antarctic sky. Known as "diamond dust," this cloud is a common sight in Antarctica. Since "diamond dust" is only produced in clear or near-clear weather, it is sometimes referred to as "clear sky precipitation". In addition, the illusionary sun phenomenon can also be observed in Antarctica[f][37].
Folded Antarctic
Months January February March April May June July August September October November December Year-round
historical maximum °C(°F) −14(7) −20
(−4
) −26
(−15) −27
(−17) −30
(−22) −31
(−24) −33
(−27) −32
(−26) −29
(−20) −29
(−20) −18
(0) −12.3
(9.9) −12.3(9.9) Uniform high temperature °C(°F) −25.9
(−14.6) −38.1
(−36.6) −50.3
(−58.5)
−54.2
(−65.6) −53.9
(−65.0) −54.4
(−65.9) −55.9
(−68.6) −55.6
(−68.1) −55.1
(−67.2) −48.4
(−55.1) −36.9(−34.4) −26.5
(−15.7) −46.3(−51.3
) uniform low temperature °C (°F) −29.4
(−20.9
)
−42.7
(−44.9) −57.0
(−70.6) −61.2
(−78.2) −61.7
(−79.1) −61.2
(−78.2) −62.8
(−81.0) −62.5
(−80.5) −62.4
(−80.3) −53.8
(−64.8) −40.4
(−40.7) −29.3
(−20.7) −52.0
(−61.6)
Historical low °C(°F) −41(−42) −57
(−71) −71(−96) −75<b1<b1131>
132>(−103) −78
(−108) −82
(−116) −80
(−112) −77
(−107) −79
(−110) −71
(−96) −55
(−67) −38(−36) −82.8
(−117.0)
Average monthly sunshine hours 558 480 217 0 0 0 0 0 0 60 434 600 589 2,938
Data source 1: [40]
Data source 2: Cool Antarctica[41]
Creature
See: An Antarctic emperor penguin (scientific name: Aptenodytes forsteri) jumps
out of the water.
Only
a small number of terrestrial vertebrates live in Antarctica [42]. Invertebrates are mostly microorganisms, including lice, nematodes, tardigrades, rotalists, krill, bullettails, and mites (such as the Antarctic beetle mite). The Antarctic midge, which is endemic to Antarctica, is a midge without flight talent, and its body size can reach 6 mm, which is the largest pure terrestrial organism in Antarctica [43]. The snow shearwater is one of only three species of birds that breed in Antarctica.[44]
Many marine animals depend directly or indirectly on phytoplankton, including penguins, blue whales, killer whales, king squids and fur seals. Gathering in large flocks that feed on plankton, Antarctic krill are a key species in the Southern Ocean ecosystem and an important food for whales, seals, leopard seals, fur seals, squid, whitebaits, penguins, albatrosses and many other birds. [45]
Penguins are representative species of the Antarctic region, and common penguin species include emperor penguins, king penguins, Adélie penguins, Antarctic penguins and Papuan penguins [46]. Rockhopping penguins have a thick ring of fur around their eyes, which makes them appear more common. With the exception of rockhopping penguins, which mainly congregate in the Falkland Islands outside Antarctica, most local penguins breed in Antarctica. Among them, the emperor penguin is the only penguin that stops breeding in the winter in Antarctica, while the Adélie penguin breeds further south to the center than other penguins.
A variety of aquatic mammals live in the left offshore waters of Antarctica, for example, between the 18th and 19th centuries, Antarctic fur sea lions were extensively hunted by seal hunters in the United States and Britain for their fur; The Weddell Seals are named after Sir James Weddell, commander of the party on the Weddell Sea expedition; Crab-eating seals live near the left Antarctica and are named after the yellow stains commonly found on the side of their mouths.
During the International Polar Year, about 500 researchers participated in a census of marine life, the results of which were released in 2010. The study is part of the Census of Marine Life (CoML), and many of its findings are noteworthy. The results indicate that more than 235 species of marine life are scattered at both poles, which has exceeded 12,000 kilometers (the distance between Antarctica and the Arctic). Local birds and large animals such as cetaceans alternate between the poles every year. Unexpectedly, some small creatures such as sea cucumbers and freely swimming snails also spread at the north and south poles. It is speculated that the reason may be that the temperature difference between the poles and the equator in the deep sea region is not large, less than 5°C, and that the ocean current system acts like an ocean conveyor belt to transport the eggs and larvae of organisms to each center. [47]
The climate of plant
Antarctica does not allow vegetation to be composed in large quantities. Cold environments, poor soil quality, lack of water and lack of sunlight inhibit plant growth. This results in very low plant diversity and very limited dispersal. There are more than seven hundred species of algae in Antarctica, the vast majority of which are phytoplankton. In summer, the coast is rich in varieties of polar snow algae and diatoms of many colors [48]. The flora on the continent is mostly composed of bryophytes. Antarctica has about 100 species of bryophytes and 25 species of land money. However, only three species of angiosperms have been found in the Antarctic continent, namely Antarctic hairgrass, Antarctic lacquer grass, and non-native precocious grasses [49]. The growth of the plant is limited to a few weeks in the summer [48][50] .
Other biological
fungi]
watermelon snow
on King George Island, Antarctica About 1,150 species of fungi have been found in Antarctica, of which about 750 are non-lichen-type fungi and 400 are lichen-type fungi [50][51]. Because they evolved under extreme conditions, some species are cave-growing and form peculiar rocks in the McMurdo Valley and surrounding ridges. The simple morphology and indistinguishable structure of fungi allow their metabolic systems and enzymes to remain active at very low temperatures, which, combined with their shortened life cycles, make them particularly suitable for surviving in harsh environments like McMurdo's Dry Valley. Their thick cell walls and intense melanin make them resistant to ultraviolet rays. Algae and blue-green algae plants also have the above characteristics, which means they can adapt to the Antarctic environment. It has been speculated that if life had ever appeared on Mars, its structure might resemble that of an Antarctic fungus (such as Cryptomyces minteri (a filarial fungus)).[52] In addition, some fungi are endemic to Antarctica, such as certain dung-dwelling species. As species develop, they must evolve to cope with a dual response: growing in feces to adapt to extremely cold environments and entering the intestines of warm-blooded animals to ensure survival.[53]
Bacteria
in Taylor Glacier, the red liquid constitutes a blood waterfall, and the red color of the liquid is due to the abundance of iron oxides.
It was once discovered that bacteria existed at depths of 800 meters under the extremely cold and dark ice [54].
In
1992, waste was dumped at the Belinskaugin station in Russia, containing old vehicles. Since the entry into force of the Protocol on the Protection of the Environment in 1998, environmental destruction such as the dumping of waste in Antarctica has been stopped.
In 1998, the Antarctic Treaty (also known as the Environmental Protection Agreement or the Madrid Protocol) relating to environmental conservation entered into force, which is the main means of maintaining and managing Antarctica's biodiversity. The Committee on Environmental Conservation initiated the Antarctic Treaty Consultative Meeting on the conservation of the Antarctic environment. One of the main concerns of the committee is to be aware of the risks posed by introduced alien species to the native ecology of Antarctica. [55]
The Antarctica Maintenance Act, passed by the United States in 1978, imposed some restrictions on activities in Antarctica. The introduction of alien plants or animals into Antarctica is punishable by criminal punishment, as if any species native to Antarctica were captured. As a result of the overfishing of krill, which play a large role in the Antarctic ecosystem, government officials have enacted fisheries regulations. The treaty, developed by the Conservation of Antarctic Marine Living Resources (CCAMLR) and entered into force in 1980, invites all Southern Ocean fishermen to consider the potential impact of their actions on the entire Antarctic ecosystem[1]. But even with these new laws in place, lack of regulation and irregularity remain a serious problem, particularly for the small-scaled toothed Antarctic fish, which is sold as Chilean bass in the United States. Illegal fishing of toothfish is increasing, reaching an estimated 32,000 tonnes (35,300 U.S. tons) in 2000.[56][57]
In October 2016, the member states of CCAMLR agreed to establish a marine maintenance area of 1.55 million square kilometers in Antarctica, of which 1.12 million square kilometers would stop fishing, which is expected to be the largest marine maintenance area in the world by that time[58].
The rockbed topography of the geological Antarctic continent is key to understanding the
dynamic movement of ice sheets.
The topography and water depth
beneath the bottom bedrock of the Antarctic Ice Sheet shows the morphology beneath the Antarctic Ice Sheet. In the legend on the left, the blue parts represent continents below sea level, and the other colors represent the parts above sea level. The height difference between adjacent colors is 760 meters. The height on the image does not correct for the potential impact of sea level rise and equilibrium rebound from the melting of the Antarctic ice sheet. <B1191 >
topographic map of Antarctica after removing the ice sheet, correcting the impact of crustal equilibrium rebound and sea level rise. Thus, the map represents what Antarctica looked like 35 million years ago when the Earth was warm enough not to produce a large ice sheet.
History of geology and paleontology
More than 170 million years ago, Antarctica was part of the Gondwana supercontinent. Over time, the Gondwana supercontinent gradually collapsed with plate movements. What is now known as Antarctica was formed 25 million years ago. Antarctica is not always cold and boring, thousands of miles frozen. For a time, Antarctica was much more northerly than it is today, and thus had a tropical and temperate climate, and was also home to many paleontological habitats. [59]
Paleozoic era (540 million years – 250 million years ago).
The Cambrian supercontinent had a mild climate. At that time, part of West Antarctica was in the northern hemisphere, and a large amount of sandstone, limestone and shale were also accumulated during this period. East Antarctica is located at the equator, the seabed that is home to invertebrates and trilobites. From the beginning of the Devonian period 416 million years ago, the Gondwana supercontinent drifted further south to the central and the climate gradually cooled, although fossils prove that plants still grew on land at that time. During this time, large amounts of sand and silt accumulated in the present-day Ellsworth Mountains, Holyck Mountains, and Pensacola Mountains. The glacial age of the Gondwana supercontinent began at the end of the Devonian period 360 million years ago, when the center of the supercontinent had reached the south pole and the climate was colder, but there was still flora on the continent. During the Permian period, terrestrial plants were dominated by seed plants, such as the genus Glossophyllum (a seed fern that grew in swamps). Over time, these wetlands became coal seams that ran beneath the Transantarctic Mountains. At the end of the Permian, large parts of the Gondwana supercontinent became hot and dry due to the continued warming of the climate. [60]
Mesozoic era (250 million years – 66 million years ago).
The continued warming of the climate has caused the polar ice caps to melt, and large parts of the Gondwana supercontinent have become deserts. East Antarctica was dotted with seed ferns and massive accumulations of sandstone and shale. In the early Triassic , mammal-like zygosycephals were common in Antarctica, including water dragons. The Antarctic Peninsula began to form during the Jurassic period (206–146 million years ago), and the surrounding islands also began to surface. Ginkgo, pine cypress, benle cycads, wood thieves, true ferns, and cycads were all quite lush during this period. The taiga occupied West Antarctica throughout the Cretaceous period (146–66 million years ago). In addition, plants of the family Australis became more and more prosperous at the end of the Cretaceous, and ammonites were also common in the seas around Antarctica. Dinosaurs were also found in Antarctica, but only three genera (Cryospinosaurus, Glaciersaurus [61] and Antarctic Ankylosaurus) have been found.[62] In addition, the Gondwana supercontinent was united from this period.
However, local indications point to the existence of marine glacial movements in Antarctica during the Cretaceous period. [63]
The collapse of the Gondwana continent (160 million years – 23 million years ago) Due
to continental expansion, ocean currents along the meridian, which originally operated between the equator and the poles, began to move in the direction of latitude. This change has changed the function of ocean currents from favoring heat exchange between the equator and the polar regions to insisting on and even increasing the temperature difference between the two. With this change, the Antarctic continent began to gradually cool.
During the Jurassic period (about 160 million years ago), the African continent separated from the Antarctic continent, and then during the Cretaceous period (about 125 million years ago), the Indian subcontinent also separated from the Antarctic continent. Until the end of the Cretaceous period, about 66 million years ago, Antarctica (then connected to Australia) had subtropical climatic types and vegetation, with marsupial fauna scattered on it [64]. After entering the Reborn era, Australia-New Guinea separated from Antarctica during the Eocene, about 40 million years ago. This change caused ocean currents moving along the latitude to separate Australia from the Antarctic continent, further affecting temperatures in Antarctica and the beginning of the ice. At the same time, during the Eocene-Oligocene extinction event about 34 million years ago, the greenhouse gas carbon dioxide levels fell to 760 ppm [65], lower than the level of more than 1000 ppm in earlier geological epochs.
About 23 million years ago, the Drake Strait between Antarctica and South America was finally completely separated, which led to the formation of the Antarctic circumpolar current. This intense current, which runs along the latitude direction, eventually separates Antarctica from the warm, low-latitude waters. Models show that further reductions in atmospheric carbon dioxide levels during the same period also have a significant impact on the temperature of the Antarctic continent [66]. As a result, the ice cover area of the Antarctic continent began to expand, and the original forest was slowly replaced by the ice sheet.
During the Neogene (23 million years ago – 50,000 years ago),
large parts of the Antarctic continent were covered by ice since about 15 million years ago. [67]
The Mel Desert flora of the Sirius Formation of the Mel Desert biophase
contains fossils of plants of the Austrolaceae family, indicating that there was an intermittent warming period in the Dominion Mountains as late as 3 million to 4 million years ago (mid-to-late Pliocene), allowing the plants of the Austral family to remain on the mountains [68]. After the Pleistocene, ice ages swept across the continent again and caused the extinction of all major plants.[69]
Antarctica's exterior hides a thick layer of ice, but long-standing geological research on Antarctica
has been blank. However, this situation has been greatly improved, and through remote sensing technologies such as ground-penetrating radar and satellite imagery, the structure of the ice under Antarctica has been gradually reminded. [70]
Geologically speaking, West Antarctica resembles the Andes Mountains of South America.[60] The Antarctic Peninsula is composed of late Paleozoic and early Mesozoic uplift and seabed sediment metamorphosis. This accumulation uplift is accompanied by ignition into intrusion and volcanic activity. In the West Antarctic region, the most common rocks are two volcanic rocks, Andesite and rhyolite, which were formed during the Jurassic period. Evidence of volcanic eruptions has also been found in the area around Mary Byrd and Alexander I Island, which continued until after the formation of the Antarctic ice sheet. The Ellsworth Mountains are a unique and unusual area of geological structure in West Antarctica, where the stratigraphic conditions are closer to East Antarctica.
The geological formations of East Antarctica are becoming more diverse. Measurements of Precambrian geology have been halted and some rocks have been found to be formed more than 3 billion years ago, mainly metamorphites and igneous rocks, which form the basis of the shield of this area. [71] On top of this substrate are rocks such as sandstone, limestone, shale that formed the Transantarctic Mountains during the Devonian and Jurassic periods, and coal seams. Some faults are also present in coastal areas such as the Shackleton Mountains and Victoria Land.
Mineral resources
: The proven mineral resources of the Antarctic continent are mainly coal [67]. The earliest record is that Frank Wilder discovered the presence of coal near the left of the Bildermore Glacier during the Nim Rhode expedition. It is now known that low-grade coal is widely dispersed throughout the Transantarctic Mountains. Most of Antarctica's major mineral resources are scattered in offshore areas. Iron ore is the largest mineral found on the Antarctic continent, mainly in the Prince Charles Mountains of East Antarctica. Its iron ore reserves are initially budgeted for 200 years for worldwide development and application.[72] In addition to iron and coal, copper, molybdenum and small amounts of gold, silver, chromium, nickel and cobalt from the Antarctic Peninsula; copper, lead, zinc, silver, tin and gold in the Trans-Antarctic Mountain Range; More than 100 deposits and occurrences have been discovered in East Antarctica such as copper, silver, tin, manganese, titanium and uranium. [73] Antarctica's oil reserves are about 50 billion ~ 100 billion barrels, and natural gas reserves are about 3,000 billion ~ 5,000 billion cubic meters, mainly scattered in the Ross Sea, the Weddell Sea and the Bellingsgaugen Sea and the Antarctic continental shelf [74][75][76].
With regard to these mineral resources, the Protocol on the Protection of the Environment of the Antarctic Treaty prohibits exploitation (except for scientific research) and is valid for 50 years from 1998, but there is currently no post-validity development agreement. [77]
See Population
: Antarctic Research Station
Some countries have permanent seminar stations in Antarctica. In winter, there are about 1,000 people working in scientific research or other related work on the continent of Antarctica and its islands near left, and about 5,000 in summer, so the population density of Antarctica is 70 and 350 people per million square kilometers in winter and summer, respectively. Many of the stations are manned throughout the year, and those wintering in Antarctica are usually on missions that last a full year. In 2004, a Trinity Church of the Russian Orthodox Church was established at the Belinsgaujin station in Russia, where one or two priests were stationed in turn every year.[78][79]
The first semi-permanent inhabitants of Antarctica near the left (south of the Antarctic Convergence) were British and American seal hunters who spent more than a year in South Georgia and the South Sandwich Islands from 1786.[71] During the whaling period, the number of people on the island exceeded 1,000 (and sometimes more than 2,000) in the summer and around 200 in the winter, until 1966. Among the whaling hunters, Norwegians made up the majority, while the British gradually increased. Their settlements include Gulidviken, Leith Harbour, King Edward Point, Stromness, Huswick, Prince Olaf, Ocean Harbour and Goldsour Bay. The director and senior personnel of the whaling station often lived with their families, including Captain Carl Anton Larsen, the founder of the Glitwiggen base. A well-known Norwegian whaler and adventurer, he obtained British citizenship with his family in 1910.
The first person to be born in the Antarctic Bands was a Norwegian baby girl, Zorfaig Jacobsen Kampotjörge. She was born in Glitwigan on 8 October 1913 and was written off by officials in South Georgia and the South Sandwich Islands. Her father was Frida Tjörf Jacobson, deputy director of the whaling station, and her mother was Clara Ollett Jacobson. Jacobson came to the island in 1904 and served as director of Glitwigan from 1914 to 1921, where two children were born [80] .
Emilio Marco Sparma was the first person to be born south of the 60th parallel (the border of Antarctica established in the Antarctic Treaty system).[81] and the first to be born on the continent. In 1978, he was born at the station of Esperanza located at the apex of the Antarctic peninsula [82][83] . His parents and seven other families arrived in Antarctica from Argentina to determine whether Antarctica was suitable for living. In 1984, Juan Pablo Camacho was born at the Eduardo Frey Montalva presidential base, becoming the first Chilean born in Antarctica. Today, several bases in Antarctica have families with small children who attend schools set up in the seminar station [84] . As of 2009, 11 children have been born in Antarctica (south of the 60th parallel), eight of whom were born at the Esperanza base in Argentina [85] and three at the Fremontalva base in Chile [86] .
At the research station
Amundsen-Scott South Pole, the full moon and an exposure time of up to 25 seconds allow the camera to be fully exposed. The survey station on the far left, the power station in the middle, and the mechanical garage in the lower right are clearly visible, while the green light in the background is the aurora.
Every year, scientists from 28 countries stop a series of experiments in Antarctica that cannot be stopped in other environments. In the summer, more than 4,000 scientists are working in scientific research stations, and by winter, the number decreases to just over 1,000.[1] McMurdo Station is the largest survey station in Antarctica, accommodating more than 1,000 scientists, visitors, and visitors at the same time.[142]
Researchers include biologists, geologists, oceanographers, physicists, astronomers, glaciologists, and climatologists: geologists focus on plate structure theory, meteorites from outer space, and geological research materials related to the collapse of Gondwana; Glaciologists focus on the history and dynamics of pack ice, seasonal snow cover, glaciers and ice sheets; In addition to studying wildlife, biologists also study the impact of harsh temperature environment and human presence on the adaptation and survival strategies of various wildlife. Doctors discuss the spread of the virus in extreme temperatures and the human body's repercussions; Astrophysicists at Amundsen-Scott South Pole Station study the celestial sphere and the cosmic microwave background radiation. Because the atmosphere at high altitudes is thin and the temperature is extremely low, the atmospheric water vapor content is low, and there is no light pollution, Antarctica has a clearer view of space than any center on Earth. As a result, astronomical observations in Antarctica are better than in other regions; In addition, 2 km below the Amundsen-Scott South Pole Station there is the world's largest neutrino telescope, which uses Antarctic ice as a shield and observation medium to observe neutrinos [143].
Since the beginning of the 70s of the 20th century, the study of the ozone layer in the atmosphere above Antarctica has become a key research direction. In 1985, three British Empire scientists dissected data collected at the Halley Research Station on the Brent Ice Shelf and found that there was an "empty" ozone layer above Antarctica. It was conclusively proven that the ozone layer was formed by human-produced chlorofluorocarbons. In 1989, the Montreal Protocol for chlorofluorocarbons entered into force, and it was estimated that the ozone layer would need to return to 1980 levels between 2050 and 2070. Under today's destruction, it may have to wait until the 22nd century.
NASA satellite data in September 2006 showed that the area of the ozone layer above Antarctica had reached 2.75 million square kilometers, the highest on record.[145] At present, researchers do not fully understand the impact of the thinning of the ozone layer on the climate of Antarctica.
In 2007, the Polar Astronomical Space Center was established. With the help of geospatial information science and remote sensing techniques, the Space Centre provided mapping services to a United States federal government-sponsored workshop. Today, the center is able to produce intact 50-centimeter-accurate maps of Antarctica every 45 days.
On September 6, 2007, the Belgian-led International Polar Foundation launched the Princess Elizabeth Station programme. Princess Elizabeth Station is the first polar science station to complete zero emissions. Its main research direction is climate change. As part of the 2008 International Year of Polar Affairs, the $17.5 million, prefabricated science station was shipped from Belgium to Antarctica at the end of the year to study and monitor the state of the environment in the polar region. Belgian polar explorer Alain Hubert said: "This science station is the first zero-emission polar science station and will be a model for how people should use energy in Antarctica." Johan Berte, the design team leader, will lead the project manager for the climatology, glaciology and microbiology workshops at the science station.
In January 2008, a team of scientists from the British Antarctic Survey (BAS), led by Hugh Cole and David Vaughn, published the results in the journal Nature Geoscience: aerial measurements of radar images indicate that a volcano erupted 2200 years ago under the Antarctic ice sheet. This burst will be the largest volcanic burst in nearly 10,000 years. Deposits of volcanic ash can be found on the ice surface beneath the Hudson Mountains, near the Pine Island glacier.
A 2014 study showed that the East Antarctic ice sheet thinned by at least 500 meters during the Pleistocene. The study also points out that the East Antarctic ice sheet has thinned by less than 50 meters since the last glacial maximum, probably starting from about 14,000 years ago.
Antarctica is known to be the center with the most meteorites , especially in East Antarctica. Meteorites from Antarctica are an important category for studying the early composition of the solar system, mostly from the collision between several asteroids in the asteroid belt to form meteorites splashing in, and carrying some material around the solar system, eventually falling to the Earth, but some may have been formed on planets. The first meteorite to be discovered in Antarctica was the Adely Land meteorite, discovered in 1912. In 1969, a Japanese expedition discovered nine meteorites, most of which had fallen on the ice over the past millions of years. The movement of the ice concentrates these meteorites in obstructive locations, such as the foot of a mountain. They were buried under snowfall for centuries before being carried to the surface by wind corrosion. Compared to meteorites collected in warmer regions of Earth, Antarctic meteorites are relatively well preserved. [150]
The abundance of meteorites allows scientists to better understand the abundance of meteorite types in the solar system and the correlations between meteorites, asteroids and comets. Some new types and rare meteorites have been discovered. They may have come from debris from the impact of the Moon and Mars. These specimens (notably ALH84001 discovered by ANSMET) are central evidence for the debate about whether microbes can exist on Mars. Because meteorites absorb and record cosmic radiation in space, laboratory studies can confirm the timing of meteorites hitting Earth. In addition to the time of the fall , meteorites can provide more useful information about the Antarctic ice environment. [150]
In 2006, a team of researchers from The Ohio State University discovered the 480-kilometer-wide Wilkes Land crater using NASA's GRACE satellite. This crater may have been formed 250 million years ago.
In January 2013, during the Belgian Antarctic Meteorite Search Mission (SAMBA), a meteorite weighing 18 kilograms was discovered on the Nansen ice sheet.
In January 2015, scientists discovered a 1.2-kilometer circular section in the surface snow of the King Baudouin Ice Shelf, which was initially speculated to be a crater. In addition, a satellite image from 25 years ago recorded exactly this location.
imitation
animation of ice bodies and global sea level
glacier movements in Antarctica Due to its proximity to the South Pole, Antarctica receives relatively little solar radiation. This means that on this extremely icy continent, water exists mainly in the form of ice. Most parts of Antarctica receive less precipitation and are dominated by snowfall. Snowfall gradually accumulates large ice sheets that cover the land,[154] while local ice sheets form ice currents that flow towards continental margins. There are also a large number of ice shelves floating on the sea near the left side of the coast of Antarctica. They are made up of glaciers flowing out into the sea [155] . For most of the year, the temperature near the left side of the coast is low enough to freeze the sea. The study of the Antarctic Ice Sheet has contributed to the understanding of its possible impact on global sea level and temperature [154].
Sea ice in Antarctica increases every winter, and most of the added sea ice melts in summer. This ice is formed by condensing from seawater and floats in the resulting waters, so it does not incur sea level rise. The area of sea ice covering the left near Antarctica has not changed much in recent decades, but researchers have not controlled for changes in its thickness. [156] [157]
Ice shelf melting does not have much impact on sea level, which can be deduced from the principle of buoyancy and the density relationship between water and ice, but if you consider that the ice that makes up the ice shelf comes from the interior of Antarctica, the melting of the ice shelf as a whole will still cause global sea level rise, although local melting water may return to land with snowfall. In recent decades, several violent ice shelf collapses have occurred near the left of the coast of Antarctica, especially around the Antarctic Peninsula. Concerned researchers are also concerned that the disturbance of the ice shelf will lead to accelerated outflow of inland ice. [158]
The ice in the interior of Antarctica contains about 70% of the world's freshwater resources [16]. The ice in this ice sheet increases with snowfall and decreases with outflow to the sea. Overall, it will increase its volume by about 82 Gt per year, resulting in an even global sea level drop of about 0.23 mm per year.
The base soil of eastern Antarctica, which occupies most of the Antarctic continent, is generally higher than sea level. Snowfall in this icy region gradually accumulates to form ice, and in some cases glaciers that flow out to the sea. It is believed that the volume increase and decrease of the East Antarctic ice sheet is generally balanced, and sometimes the volume of the ice sheet will increase slightly.[160][161][162] However, some areas of the region are showing signs of accelerated ice outflow.
Impact
of global warming on Antarctica: Temperatures are rising in parts of Antarctica, especially near the left of the Antarctic Peninsula. A study published in 2009 showed that the Antarctic continent warmed by more than 0.05°C per decade between 1957 and 2006, and West Antarctica warmed by more than 0.1°C per decade over 50 years. This phenomenon is particularly pronounced in winter and spring, and warming is partially offset by autumn cooling in East Antarctica [164]. There have also been studies suggesting that Antarctica's warming is caused by human carbon dioxide emissions, but this claim is still controversial. Although the surface warming of West Antarctica is large, it has not formed a large-scale melting of ice in the region, nor has it directly affected the effect of the West Antarctic ice sheet on sea level rise. Conversely, the accelerated outflow of glaciers in recent years is thought to have been formed by warm water flowing into the deep ocean on the left side of the continental shelf. The net impact on sea level in the Antarctic Peninsula is more likely to be caused by greater atmospheric warming].
In 2002, the Larsen Ice Shelf on the Antarctic Peninsula collapsed [170] . Between February 28 and March 8, 2008, about 570 square kilometers of ice in the Wilkins Ice Shelf on the southwestern side of the Antarctic Peninsula also collapsed. The remaining 15,000 square kilometers of ice are supported by a band of ice about 6 kilometers wide and are also on the verge of collapse. On April 5, 2009, the ice collapsed completely. According to NASA, in 2005, the largest melting of the outer surface ice of the Antarctic continent in 30 years, a piece of ice about the size of California, the United States, was frozen again after a brief melt. This may have been formed by local temperatures of up to 5°C [175]. A study published in 2013 showed that central Antarctica may be one of the fastest warming regions on Earth. The researchers presented records of the average annual temperature at Bird Station from 1958 to 2010, showing that the average annual temperature in this area increased linearly by 2.4±1.2°C during this time.
The area over Antarctica that is the area of the ozone layer formed by the accumulation of chlorofluorocarbons reached its highest recorded level in September 2006.
Main article: Ozone layer is empty
Every year from August to October, the ozone layer is flooded over Antarctica. In this region, atmospheric ozone levels are quite low. This emptiness simply obscures the entire Antarctic continent. In 1985, a British Antarctic team described the ozone layer in an article published in the journal Nature. This report has drawn the world's attention to this issue. Since its observation, the area of the ozone layer has remained high. In September 2006, its area reached its highest level on record. According to existing records, the longest-standing void will continue to exist until the beginning of January of the following year. The ozone layer is formed by the release of chlorofluorocarbons into the atmosphere, which catalyze the conversion of ozone into oxygen.
Some scientific studies have shown that the ozone layer is one of the leading factors of climate change in Antarctica and other regions of the southern hemisphere. Ozone absorbs large amounts of ultraviolet rays radiated into the stratosphere and converts them into heat. The ozone layer over Antarctica will form the temperature of the stratosphere in this area, dropping by about 6 °C. This effect will strengthen the polar vortex formed by the westerly winds around the continent, and the cold air near the left of the South Pole will not flow out, further causing the temperature of the ice in East Antarctica to decrease, and the ice temperature in the surrounding area of Antarctica, especially the Antarctic Peninsula, will increase, and accelerate the condensation of ice in the region [179]. The modelling analysis also suggests that the abundance of the ozone layer and the strengthening of polar vortexes are also responsible for the recent increase in left-near ice floes along the coast of the Antarctic continent.