As a result of continued warming, the polar ice caps melted and much of Gondwana became a desert. In Eastern Antarctica, seed ferns or pteridosperms became abundant and large amounts of sandstone and shale were laid down at this time. Synapsids , commonly known as "mammal-like reptiles", were common in Antarctica during the Early Triassic and included forms such as Lystrosaurus.
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Ginkgo trees, conifers, bennettites, horsetails, ferns and cycads were plentiful during this period. Ammonites were common in the seas around Antarctica, and dinosaurs were also present, though only three Antarctic dinosaur genera Cryolophosaurus and Glacialisaurus , from the Hanson Formation , [58] and Antarctopelta have been described to date.
However, there is some evidence of antarctic marine glaciation during the Cretaceous period. The cooling of Antarctica occurred stepwise, as the continental spread changed the oceanic currents from longitudinal equator-to-pole temperature-equalising currents to latitudinal currents that preserved and accentuated latitude temperature differences.
Models of the changes suggest that declining CO 2 levels became more important. Since about 15 Ma, the continent has been mostly covered with ice. Fossil Nothofagus leaves in the Meyer Desert Formation of the Sirius Group show that intermittent warm periods allowed Nothofagus shrubs to cling to the Dominion Range as late as 3—4 Ma mid-late Pliocene.
The geological study of Antarctica has been greatly hindered by nearly all of the continent being permanently covered with a thick layer of ice. This sediment uplift was accompanied by igneous intrusions and volcanism. The most common rocks in West Antarctica are andesite and rhyolite volcanics formed during the Jurassic period.
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There is also evidence of volcanic activity, even after the ice sheet had formed, in Marie Byrd Land and Alexander Island. The only anomalous area of West Antarctica is the Ellsworth Mountains region, where the stratigraphy is more similar to East Antarctica. It is composed of a metamorphic and igneous platform which is the basis of the continental shield. On top of this base are coal and various modern rocks, such as sandstones , limestones and shales laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains.
In coastal areas such as Shackleton Range and Victoria Land some faulting has occurred. The main mineral resource known on the continent is coal. The Prince Charles Mountains contain significant deposits of iron ore. The most valuable resources of Antarctica lie offshore, namely the oil and natural gas fields found in the Ross Sea in Exploitation of all mineral resources is banned until by the Protocol on Environmental Protection to the Antarctic Treaty. Antarctica is the coldest of Earth 's continents.
It used to be ice-free until about 34 million years ago, when it became covered with ice. Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it. Given the latitude, long periods of constant darkness or constant sunlight create climates unfamiliar to human beings in much of the rest of the world.
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. Despite the lack of precipitation over the central portion of the continent, ice there lasts for extended periods. Heavy snowfalls are common on the coastal portion of the continent, where snowfalls of up to 1.
At the edge of the continent, strong katabatic winds off the polar plateau often blow at storm force. In the interior, wind speeds are typically moderate. During clear days in summer, more solar radiation reaches the surface at the South Pole than at the equator because of the 24 hours of sunlight each day at the Pole.
Antarctica is colder than the Arctic for three reasons. Second, the Arctic Ocean covers the north polar zone: Third, the Earth is at aphelion in July i. The orbital distance contributes to a colder Antarctic winter and a warmer Antarctic summer but the first two effects have more impact. The aurora australis , commonly known as the southern lights, is a glow observed in the night sky near the South Pole created by the plasma-full solar winds that pass by the Earth.
Another unique spectacle is diamond dust , a ground-level cloud composed of tiny ice crystals. It generally forms under otherwise clear or nearly clear skies, so people sometimes also refer to it as clear-sky precipitation. A sun dog , a frequent atmospheric optical phenomenon , is a bright "spot" beside the true sun. Several governments maintain permanent manned research stations on the continent. The number of people conducting and supporting scientific research and other work on the continent and its nearby islands varies from about 1, in winter to about 5, in the summer, giving it a population density between 70 and inhabitants per million square kilometres and per million square miles at these times.
Many of the stations are staffed year-round, the winter-over personnel typically arriving from their home countries for a one-year assignment. An Orthodox church — Trinity Church , opened in at the Russian Bellingshausen Station —is manned year-round by one or two priests, who are similarly rotated every year. The first semi-permanent inhabitants of regions near Antarctica areas situated south of the Antarctic Convergence were British and American sealers who used to spend a year or more on South Georgia , from onward.
During the whaling era, which lasted until , the population of that island varied from over 1, in the summer over 2, in some years to some in the winter. Most of the whalers were Norwegian, with an increasing proportion of Britons. Managers and other senior officers of the whaling stations often lived together with their families. Among them was the founder of Grytviken, Captain Carl Anton Larsen , a prominent Norwegian whaler and explorer who, along with his family, adopted British citizenship in She was a daughter of Fridthjof Jacobsen, the assistant manager of the whaling station, and Klara Olette Jacobsen.
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Jacobsen arrived on the island in and became the manager of Grytviken, serving from to ; two of his children were born on the island. Emilio Marcos Palma was the first person born south of the 60th parallel south the continental limit according to the Antarctic Treaty , [77] as well as the first one born on the Antarctic mainland, in at Base Esperanza , on the tip of the Antarctic Peninsula; [78] [79] his parents were sent there along with seven other families by the Argentine government to determine if the continent was suitable for family life. Several bases are now home to families with children attending schools at the station.
Few terrestrial vertebrates live in Antarctica, and those that do are limited to the sub-Antarctic islands.
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Some species of marine animals exist and rely, directly or indirectly, on the phytoplankton. Antarctic sea life includes penguins , blue whales , orcas , colossal squids and fur seals. The southern rockhopper penguin has distinctive feathers around the eyes, giving the appearance of elaborate eyelashes. King penguins , chinstrap penguins , and gentoo penguins also breed in the Antarctic. The Antarctic fur seal was very heavily hunted in the 18th and 19th centuries for its pelt by sealers from the United States and the United Kingdom.
Antarctic krill , which congregate in large schools , is the keystone species of the ecosystem of the Southern Ocean , and is an important food organism for whales, seals, leopard seals , fur seals, squid , icefish , penguins, albatrosses and many other birds. A census of sea life carried out during the International Polar Year and which involved some researchers was released in The research is part of the global Census of Marine Life and has disclosed some remarkable findings. Large animals such as some cetaceans and birds make the round trip annually.
More surprising are small forms of life such as sea cucumbers and free-swimming snails found in both polar oceans. About 1, species of fungi have been recorded from Antarctica, of which about are non-lichen-forming and are lichen-forming. The apparently simple morphology, scarcely differentiated structures, metabolic systems and enzymes still active at very low temperatures, and reduced life cycles shown by such fungi make them particularly suited to harsh environments such as the McMurdo Dry Valleys.
In particular, their thick-walled and strongly melanised cells make them resistant to UV light. Those features can also be observed in algae and cyanobacteria , suggesting that these are adaptations to the conditions prevailing in Antarctica. This has led to speculation that, if life ever occurred on Mars, it might have looked similar to Antarctic fungi such as Cryomyces antarcticus , and Cryomyces minteri. Endemic Antarctic fungi also include certain dung-inhabiting species which have had to evolve in response to the double challenge of extreme cold while growing on dung, and the need to survive passage through the gut of warm-blooded animals.
About million years ago Permian forests started to cover the continent, and tundra vegetation survived as late as 15 million years ago, [92] but the climate of present-day Antarctica does not allow extensive vegetation to form. A combination of freezing temperatures, poor soil quality, lack of moisture, and lack of sunlight inhibit plant growth. As a result, the diversity of plant life is very low and limited in distribution.
The flora of the continent largely consists of bryophytes.
There are about species of mosses and 25 species of liverworts , but only three species of flowering plants , all of which are found in the Antarctic Peninsula: Deschampsia antarctica Antarctic hair grass , Colobanthus quitensis Antarctic pearlwort and the non-native Poa annua annual bluegrass. Seven hundred species of algae exist, most of which are phytoplankton. Multicoloured snow algae and diatoms are especially abundant in the coastal regions during the summer.
The Protocol on Environmental Protection to the Antarctic Treaty also known as the Environmental Protocol or Madrid Protocol came into force in , and is the main instrument concerned with conservation and management of biodiversity in Antarctica. The Antarctic Treaty Consultative Meeting is advised on environmental and conservation issues in Antarctica by the Committee for Environmental Protection.
A major concern within this committee is the risk to Antarctica from unintentional introduction of non-native species from outside the region. The passing of the Antarctic Conservation Act in the U. The introduction of alien plants or animals can bring a criminal penalty, as can the extraction of any indigenous species. The overfishing of krill , which plays a large role in the Antarctic ecosystem, led officials to enact regulations on fishing. Several countries claim sovereignty in certain regions. While a few of these countries have mutually recognised each other's claims, [99] the validity of these claims is not recognised universally.
New claims on Antarctica have been suspended since , although in Norway formally defined Queen Maud Land as including the unclaimed area between it and the South Pole. This was the first arms control agreement established during the Cold War. In the Antarctic Treaty Parties began negotiations on a convention to regulate mining in Antarctica. They proposed instead that a comprehensive regime to protect the Antarctic environment be negotiated in its place.
The Antarctic Treaty prohibits any military activity in Antarctica , including the establishment of military bases and fortifications, military manoeuvres, and weapons testing. Military personnel or equipment are permitted only for scientific research or other peaceful purposes. The Argentine, British and Chilean claims all overlap, and have caused friction. The areas shown as Australia's and New Zealand's claims were British territory until they were handed over following the countries' independence.
Australia currently claims the largest area. Other countries participating as members of the Antarctic Treaty have a territorial interest in Antarctica, but the provisions of the Treaty do not allow them to make their claims while it is in force. There is no economic activity in Antarctica at present, except for fishing off the coast and small-scale tourism , both based outside Antarctica. Although coal, hydrocarbons , iron ore, platinum , copper , chromium , nickel , gold and other minerals have been found, they have not been in large enough quantities to exploit.
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In , a compromise agreement was reached to place an indefinite ban on mining, to be reviewed in , further limiting economic development and exploitation. The primary economic activity is the capture and offshore trading of fish. Travel is largely by small or medium ship, focusing on specific scenic locations with accessible concentrations of iconic wildlife. A total of 37, tourists visited during the —07 Austral summer with nearly all of them coming from commercial ships; 38, were recorded in — There has been some concern over the potential adverse environmental and ecosystem effects caused by the influx of visitors.
Some environmentalists and scientists have made a call for stricter regulations for ships and a tourism quota. Antarctic sightseeing flights which did not land operated out of Australia and New Zealand until the fatal crash of Air New Zealand Flight in on Mount Erebus, which killed all aboard. Qantas resumed commercial overflights to Antarctica from Australia in the mids.
About thirty countries maintain about seventy research stations 40 year-round or permanent, and 30 summer-only in Antarctica, with an approximate population of in summer and in winter. Different country calling codes and currencies [] are used for different settlements, depending on the administrating country. The Antarctican dollar, a souvenir item sold in the United States and Canada, is not legal tender.
Each year, scientists from 28 different nations conduct experiments not reproducible in any other place in the world. In the summer more than 4, scientists operate research stations ; this number decreases to just over 1, in the winter. Researchers include biologists , geologists , oceanographers , physicists , astronomers , glaciologists , and meteorologists. Geologists tend to study plate tectonics , meteorites from outer space , and resources from the breakup of the supercontinent Gondwana. Glaciologists in Antarctica are concerned with the study of the history and dynamics of floating ice, seasonal snow , glaciers , and ice sheets.
Biologists, in addition to examining the wildlife, are interested in how harsh temperatures and the presence of people affect adaptation and survival strategies in a wide variety of organisms. Medical physicians have made discoveries concerning the spreading of viruses and the body's response to extreme seasonal temperatures. Astrophysicists at Amundsen—Scott South Pole Station study the celestial dome and cosmic microwave background radiation.
Many astronomical observations are better made from the interior of Antarctica than from most surface locations because of the high elevation, which results in a thin atmosphere; low temperature, which minimises the amount of water vapour in the atmosphere; and absence of light pollution , thus allowing for a view of space clearer than anywhere else on Earth. Since the s an important focus of study has been the ozone layer in the atmosphere above Antarctica.
In , three British scientists working on data they had gathered at Halley Station on the Brunt Ice Shelf discovered the existence of a hole in this layer. It was eventually determined that the destruction of the ozone was caused by chlorofluorocarbons CFCs emitted by human products.
With the ban of CFCs in the Montreal Protocol of , climate projections indicate that the ozone layer will return to levels between and In The Polar Geospatial Center was founded. The Polar Geospatial Center uses geospatial and remote sensing technology to provide mapping services to American federally funded research teams. On 6 September Belgian-based International Polar Foundation unveiled the Princess Elisabeth station , the world's first zero-emissions polar science station in Antarctica to research climate change. Belgian polar explorer Alain Hubert stated: The biggest eruption in Antarctica in the last 10, years, the volcanic ash was found deposited on the ice surface under the Hudson Mountains , close to Pine Island Glacier.
Meteorites from Antarctica are an important area of study of material formed early in the solar system ; most are thought to come from asteroids , but some may have originated on larger planets. The first meteorite was found in , and named the Adelie Land meteorite. In , a Japanese expedition discovered nine meteorites. Most of these meteorites have fallen onto the ice sheet in the last million years. Motion of the ice sheet tends to concentrate the meteorites at blocking locations such as mountain ranges, with wind erosion bringing them to the surface after centuries beneath accumulated snowfall.
Compared with meteorites collected in more temperate regions on Earth, the Antarctic meteorites are well-preserved. This large collection of meteorites allows a better understanding of the abundance of meteorite types in the solar system and how meteorites relate to asteroids and comets.
New types of meteorites and rare meteorites have been found. Among these are pieces blasted off the Moon, and probably Mars, by impacts. Because meteorites in space absorb and record cosmic radiation, the time elapsed since the meteorite hit the Earth can be determined from laboratory studies. The elapsed time since fall, or terrestrial residence age, of a meteorite represents more information that might be useful in environmental studies of Antarctic ice sheets.
In January reports emerged of a 2-kilometre 1. Satellite images from 25 years ago seemingly show it. Due to its location at the South Pole, Antarctica receives relatively little solar radiation except along the southern summer. This means that it is a very cold continent where water is mostly in the form of ice. Precipitation is low most of Antarctica is a desert and almost always in the form of snow, which accumulates and forms a giant ice sheet which covers the land.
Parts of this ice sheet form moving glaciers known as ice streams , which flow towards the edges of the continent. Next to the continental shore are many ice shelves. These are floating extensions of outflowing glaciers from the continental ice mass. Offshore, temperatures are also low enough that ice is formed from seawater through most of the year. It is important to understand the various types of Antarctic ice to understand possible effects on sea levels and the implications of global cooling.
Sea ice extent expands annually in the Antarctic winter and most of this ice melts in the summer. This ice is formed from the ocean water and floats in the same water and thus does not contribute to rise in sea level. The extent of sea ice around Antarctica has remained roughly constant in recent decades, although the thickness changes are unclear.
Melting of floating ice shelves ice that originated on the land does not in itself contribute much to sea-level rise since the ice displaces only its own mass of water. However, it is the outflow of the ice from the land to form the ice shelf which causes a rise in global sea level. This effect is offset by snow falling back onto the continent. Recent decades have witnessed several dramatic collapses of large ice shelves around the coast of Antarctica, especially along the Antarctic Peninsula.
Concerns have been raised that disruption of ice shelves may result in increased glacial outflow from the continental ice mass. A single study by H. Jay Zwally et al. East Antarctica is a cold region with a ground base above sea level and occupies most of the continent. This area is dominated by small accumulations of snowfall which becomes ice and thus eventually seaward glacial flows. The mass balance of the East Antarctic Ice Sheet as a whole is thought to be slightly positive lowering sea level or near to balance. Some of Antarctica has been warming up; particularly strong warming has been noted on the Antarctic Peninsula.
This study also noted that West Antarctica has warmed by more than 0. This is partly offset by autumn cooling in East Antarctica. Instead the recent increases in glacier outflow are believed to be due to an inflow of warm water from the deep ocean, just off the continental shelf. In the Antarctic Peninsula's Larsen-B ice shelf collapsed. A study published in Nature Geoscience in online in December identified central West Antarctica as one of the fastest-warming regions on Earth. The researchers present a complete temperature record from Antarctica's Byrd Station and assert that it "reveals a linear increase in annual temperature between and by 2.
There is a large area of low ozone concentration or " ozone hole " over Antarctica. This hole covers almost the whole continent and was at its largest in September , when the longest lasting hole on record remained until the end of December. The ozone hole is attributed to the emission of chlorofluorocarbons or CFCs into the atmosphere, which decompose the ozone into other gases. Some scientific studies suggest that ozone depletion may have a dominant role in governing climatic change in Antarctica and a wider area of the Southern Hemisphere.
This cooling has the effect of intensifying the westerly winds which flow around the continent the polar vortex and thus prevents outflow of the cold air near the South Pole. As a result, the continental mass of the East Antarctic ice sheet is held at lower temperatures, and the peripheral areas of Antarctica, especially the Antarctic Peninsula, are subject to higher temperatures, which promote accelerated melting.
From Wikipedia, the free encyclopedia. This article is about the continent. For other uses, see Antarctica disambiguation. Polar continent in the Earth's southern hemisphere. List of Antarctic expeditions and Women in Antarctica. Historical claims to continental Antarctica. Extreme points of Antarctica and List of Antarctic and subantarctic islands. Meyer Desert Formation biota. Antarctic ecozone , Antarctic flora , Antarctic microorganism , and Wildlife of Antarctica.
Territorial claims in Antarctica. Research stations in Antarctica. Current sea level rise. Global warming in Antarctica and Antarctic sea ice. Government of the United States. Retrieved 14 September The Fight for English. Retrieved 16 November Retrieved 6 January Archived from the original on 13 November Retrieved 13 November Alan 18 January Archived from the original on 4 March Retrieved 7 February Retrieved 12 July In Crane, Gregory R. Retrieved 18 November Book II, Part 5. A Treatise on the Astrolabe. Lying for the Admiralty: Captain Cook's Endeavour Voyage.
Retrieved 25 January Archived from the original on 7 February Retrieved 12 February Penguin Books, , p. Archived PDF from the original on 17 February Retrieved 6 February Archived from the original on 2 February University of the City of San Diego. Archived from the original on 10 February Additionally, they were quick to see the conflict in Vietnam as a civil war. This gave the students a different understanding of wartime atrocities from American students.
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While condemning violence, my students in Slovenia and Colombia were much more likely to argue that there can be no effective rules governing wartime behavior because a warring nation and its people will do whatever is necessary to win. Strom in Villa de Leyva, a Spanish colonial city high in the Andes. What were your favorite parts of the experience outside the classroom? While I was in residence in the two countries, I tried to travel as much as possible.
I did a number of jungle hikes and saw pink dolphins in the river. It was quite an amazing experience. Quite a different experience stands out from my time in Slovenia. The city is quite lovely but still bears the scars from being besieged by Serbian forces in the s. The siege lasted nearly four years, and more than 10, residents were killed as they went about their daily lives—shopping, going to school, getting water.
After the conclusion of hostilities, the city reburied its dead in huge graveyards with white headstones that can be seen from the air as you fly in. They were a moving and disturbing sight. A couple of years ago, the Rollins history department sponsored a Fulbright Research Scholar from Slovenia. Was that connected to your Fulbright in Slovenia? Kornelija Ajlec in to come to Rollins as a Fulbright Scholar. She was developing a project on U. She spent six weeks on campus, during which time we met regularly to discuss her research.
She also gave a public lecture and engaged with our students in and out of the classroom. She was fascinated by the type of pedagogy she saw at Rollins and wanted to learn more. This resulted in my invitation to team-teach with her in Slovenia. You also used your time in Colombia and Slovenia to develop a pair of future field studies.
Can you tell us more about that process and what those field studies might look like? Right now, we are imagining focusing on several areas of interest: We want to explore the environmental diversity of Colombia with side trips in the Andes and to the Amazon; we want to investigate the strategies that are being used to integrate the FARC guerillas successfully into mainstream Colombian society; and we want to set up at least one meeting with faculty members at Colombian institutions to compare research and teaching ideas.
The second trip that I am planning, with Rollins history professor Hannah Ewing, is a field study for history students and others. It will also explore how the conflict in the Balkans magnified extant ethnic conflicts, fostering violence that lasted into the s and included the Siege of Sarajevo. In addition to teaching and field study planning, you also conducted research throughout your sabbatical. Can you tell us more about that work? This was an intensive research project that required reading the entire journal, and my time in Colombia gave me the space to do this.
We surveyed the students about their perceptions of the course and also talked about what we had learned from the co-teaching experiment.