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126-495: Tanna (sometimes misspelled Tana ) is an island in southern Vanuatu . Tanna is the most populous island of Tafea Province , and the third most populous in the whole country (after Efate and Espiritu Santo ). It is home to five indigenous languages , which also rank among the most vibrant in the whole archipelago, ranging from 3500 to 11500 speakers. Tanna is the most internationally renowned island of Vanuatu, and has been featured in numerous documentaries or TV shows around

252-578: A continent by plate tectonics , and oceanic islands, which have never been part of a continent. Oceanic islands can be formed from volcanic activity, grow into atolls from coral reefs , and form from sediment along shorelines, creating barrier islands . River islands can also form from sediment and debris in rivers. Artificial islands are those made by humans, including small rocky outcroppings built out of lagoons and large-scale land reclamation projects used for development. Islands are host to diverse plant and animal life. Oceanic islands have

378-451: A "commuting" distance to an island that has enough resources to be sustainable. The presence of an island is marked by seabirds , differences in cloud and weather patterns, as well as changes in the direction of waves. It is also possible for human populations to have gone extinct on islands, evidenced by explorers finding islands that show evidence of habitation but no life. Not all islands were or are inhabited by maritime cultures. In

504-509: A "rafting event". This phenomenon is known as oceanic dispersal . Tropical storms have the capacity to transport species over great distances. Animals like tortoises can live for weeks without food or water, and are able to survive floating on debris in the sea. One case study showed that in 1995, fifteen iguanas survived a 300 km journey to Anguilla in the Caribbean , an island which no iguana had lived on previously. They survived floating on

630-556: A cooler West Pacific and a warmer East Pacific, leading to a shift of cloudiness and rainfall towards the East Pacific. This situation is called El Niño. The opposite occurs if trade winds are stronger than average, leading to a warmer West Pacific and a cooler East Pacific. This situation is called La Niña and is associated with increased cloudiness and rainfall over the West Pacific. The close relationship between ocean temperatures and

756-581: A decrease in the strength of the Pacific trade winds , and a reduction in rainfall over eastern and northern Australia. La Niña episodes are defined as sustained cooling of the central and eastern tropical Pacific Ocean, thus resulting in an increase in the strength of the Pacific trade winds , and the opposite effects in Australia when compared to El Niño. Although the Southern Oscillation Index has

882-426: A detailed review of 1,288 islands found that they were home to 1,189 highly-threatened vertebrate species, which was 41 percent of the global figure. Coral bleaching is expected to occur with more frequency, threatening marine ecosystems, some of which island economies are dependent on. Some islands that are low-lying may cease to exist given high enough amounts of sea level rise. Tuvalu received media attention for

1008-609: A few meters high, and are usually temporary. Changes in the flow speed, water level, and sediment content of the river may effect the rate of fluvial island formation and depletion. Permanent river islands also exist, the largest of which (that is completely inland) is Bananal Island in the Tocantins of Brazil, which has a maximum width of 55 kilometers. Lakes form for a variety of reasons, including glaciers , plate tectonics, and volcanism. Lake islands can form as part of these processes. The field of insular biogeography studies

1134-402: A higher carrying capacity also have more genetic diversity , which promotes speciation . Oceanic islands, ones that have never been connected to shore, are only populated by life that can cross the sea. This means that any animals present on the island had to have flown there, in the case of birds or bats , were carried by such animals, or were carried in a sea current in what is known as

1260-485: A larger EP ENSO occurrence, or even displaying opposite conditions from the observed ones in the other Niño regions when accompanied by Modoki variations. ENSO Costero events usually present more localized effects, with warm phases leading to increased rainfall over the coast of Ecuador, northern Peru and the Amazon rainforest , and increased temperatures over the northern Chilean coast, and cold phases leading to droughts on

1386-533: A long station record going back to the 1800s, its reliability is limited due to the latitudes of both Darwin and Tahiti being well south of the Equator, so that the surface air pressure at both locations is less directly related to ENSO. To overcome this effect, a new index was created, named the Equatorial Southern Oscillation Index (EQSOI). To generate this index, two new regions, centered on

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1512-472: A loss of almost all the infrastructure in Dominica. Sea level rise and other climate changes can reduce freshwater reserves, resulting in droughts . These risks are expected to decrease the habitability of islands, especially small ones. Beyond risks to human life, plant and animal life are threatened. It has been estimated that almost 50 percent of land species threatened by extinction live on islands. In 2017,

1638-403: A mass of uprooted trees from a storm. Plant species are thought to be able to travel great distances of ocean. New Zealand and Australia share 200 native plant species, despite being separated by 1500 km. Continental islands, islands that were at one point connected to a continent, are expected to share a common history of plant and animal life up until the point that the island broke away from

1764-782: A minimum. Some islands became host to humans due to a land bridge or a continental island splitting from the mainland. Today, up to 10% of the world's population lives on islands. Islands are popular targets for tourism due to their perceived natural beauty, isolation, and unique cultures. Islands became the target of colonization by Europeans, resulting in the majority of islands in the Pacific being put under European control. Decolonization has resulted in some but not all island nations becoming self-governing , with lasting effects related to industrialisation , invasive species , nuclear weapons testing , and tourism . Islands and island countries are threatened by climate change . Sea level rise threatens to submerge nations such as Maldives ,

1890-743: A minority. Cultural attitudes related to communal ownership of land as well as a lack of individualistic decision-making may make some island cultures less compatible with the global capitalist economy, causing these nations to experience less economic growth. Islands have long been a popular target for tourism , thanks to their unique climates, cultures, and natural beauty. However, islands may suffer from poor transportation connectivity from airplanes and boats and strains on infrastructure from tourist activity. Islands in colder climates often rely on seasonal tourists seeking to enjoy nature or local cultures, and may only be one aspect of an island's economy. In contrast, tourism on tropical islands can often make up

2016-411: A negative SSH anomaly (lowered sea level) via contraction. The El Niño–Southern Oscillation is a single climate phenomenon that quasi-periodically fluctuates between three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases which require certain changes to take place in both the ocean and the atmosphere before an event is declared. The cool phase of ENSO is La Niña, with SST in

2142-599: A permanent caisson , a steel or concrete structure built in a closed loop and then filled with sand. Some modern islands have been constructed by pouring millions of tons of sand into the sea, such as with Pearl Island in Qatar or the Palm Islands in Dubai. These islands are usually created for real estate development , and are sold for private ownership or construction of housing. Offshore oil platforms have also been described as

2268-524: A phenomenon where new oceanic crust is formed, pushing away older crust. Islands sitting on the continental shelf may be called continental islands. Other islands, like those that make up New Zealand , are what remains of continents that shrank and sunk beneath the sea. It was estimated that Zealandia , the continent-like area of crust that New Zealand sits on, has had 93% of its original surface area submerged. Some islands are formed when coral reefs grow on volcanic islands that have submerged beneath

2394-423: A press conference publicizing the ongoing submerging of the island country. Tuvalu signed a cooperation agreement with Australia agreeing to annually allow 280 of its citizens to become permanent residents of Australia. The Marshall Islands, a country of 1,156 islands, have also been identified as a country that may be existentially threatened by rising seas. Increasing intensity of tropical storms also increases

2520-483: A priority target of conservation efforts, to prevent the extinction of these species. Despite high levels of endemism, the total species richness , the total number of unique species in a region, is lower on islands than on mainlands. The level of species richness on islands is proportional to the area of that island, a phenomenon known as the species-area relationship . This is because larger areas have more resources and thus can support more organisms. Populations with

2646-517: A quarter of the planet, and particularly in the form of temperature at the ocean surface, can have a significant effect on weather across the entire planet. Tropical instability waves visible on sea surface temperature maps, showing a tongue of colder water, are often present during neutral or La Niña conditions. La Niña is a complex weather pattern that occurs every few years, often persisting for longer than five months. El Niño and La Niña can be indicators of weather changes across

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2772-411: A restricted set of natural resources. However, these nations control some of the largest fisheries in the world, deposits of copper , gold , and nickel , as well as oil deposits . The natural beauty of island nations also makes them a magnet for tourism . Islands also have geopolitical value for naval bases , weapons testing , and general territorial control. One such example is French Polynesia ,

2898-425: A secondary peak in sea surface temperature across the far eastern equatorial Pacific Ocean sometimes follows the initial peak. An especially strong Walker circulation causes La Niña, which is considered to be the cold oceanic and positive atmospheric phase of the broader El Niño–Southern Oscillation (ENSO) weather phenomenon, as well as the opposite of El Niño weather pattern, where sea surface temperature across

3024-468: A selection pressure for smaller animals that require less food. Having fewer predators would mean these animals did not need not be large to survive. Charles Darwin formulated the theory of natural selection through the study of island ecology. The species he observed on the Galápagos Islands , including tanager birds, contributed to his understanding of how evolution works. He first traveled to

3150-509: A specific property known as adaptive radiation . In this process, a species that arrives on a group of islands rapidly becomes more diverse over time, splitting off into new species or subspecies. A species that reaches an island ecosystem may face little competition for resources, or may find that the resources that they found in their previous habitat are not available. These factors together result in individual evolutionary branches with different means of survival. The classical example of this

3276-414: A territory that receives substantial military expenditure and aid from France. Since the first discoveries of Polynesian, Micronesian , and other islands by Westerners, these nations have been the subject of colonization. Islands were the target of Christian missionaries . These missionaries faced resistance, but found success when some local chiefs used European support to centralize power. Beginning in

3402-462: A tree that is present in Australia, New Zealand, parts of South American, and New Guinea, places that today are geographically distant. A possible explanation for this phenomenon is that these landmasses were once all part of the continent Gondwana and separated by tectonic drift. However, there are competing theories that suggest this species may have reached faraway places by way of oceanic dispersal. Species that colonize island archipelagos exhibit

3528-603: A type of island. Some atolls have been covered in concrete to create artificial islands for military purposes, such as those created by China in the South China Sea . These atolls were previously low-tide elevations, landmasses that are only above water during low tide . The United Nations Convention on the Law of the Sea indicates that these islands may not have the same legal status as a naturally occurring island, and as such may not confer

3654-507: Is Darwin's finches , a group of up to fifteen tanager species that are endemic to the Galápagos Islands. These birds evolved different beaks in order to eat different kinds of food available on the islands. The large ground finch has a large bill used to crack seeds and eat fruit. The Genovesa cactus finch prefers cacti as a food source, and has a beak adapted for removing pulp and flowers from cacti. The green warbler-finch (in

3780-588: Is actually a cognate of Swedish ö and German Aue , and more distantly related to Latin aqua (water). The spelling of the word was modified in the 15th century because of a false etymology caused by an association with the Old French loanword isle , which itself comes from the Latin word insula . Islands often are found in archipelagos or island chains, which are collections of islands. These chains are thought to form from volcanic hotspots , areas of

3906-583: Is an oscillation in surface air pressure between the tropical eastern and the western Pacific Ocean waters. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI). The SOI is computed from fluctuations in the surface air pressure difference between Tahiti (in the Pacific) and Darwin, Australia (on the Indian Ocean). El Niño episodes have negative SOI, meaning there

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4032-471: Is detailed. There are five main languages spoken on Tanna: the southern language of Kwamera and the Southwestern language adjacent to the slopes of Tokosmera, of which there are many dialects spoken by very small groupings, constitute two of the languages. The remaining majority of Tanna islanders speak four dialects, being North Tanna in the northwest, Lénakel in the west-central area near Lénakel, and

4158-405: Is known as Ekman transport . Colder water from deeper in the ocean rises along the continental margin to replace the near-surface water. This process cools the East Pacific because the thermocline is closer to the ocean surface, leaving relatively little separation between the deeper cold water and the ocean surface. Additionally, the northward-flowing Humboldt Current carries colder water from

4284-520: Is longer, it is classified as an El Niño "episode". It is thought that there have been at least 30 El Niño events between 1900 and 2024, with the 1982–83 , 1997–98 and 2014–16 events among the strongest on record. Since 2000, El Niño events have been observed in 2002–03, 2004–05, 2006–07, 2009–10, 2014–16 , 2018–19, and 2023–24 . Major ENSO events were recorded in the years 1790–93, 1828, 1876–78, 1891, 1925–26, 1972–73, 1982–83, 1997–98, 2014–16, and 2023–24. During strong El Niño episodes,

4410-553: Is lower pressure over Tahiti and higher pressure in Darwin. La Niña episodes on the other hand have positive SOI, meaning there is higher pressure in Tahiti and lower in Darwin. Low atmospheric pressure tends to occur over warm water and high pressure occurs over cold water, in part because of deep convection over the warm water. El Niño episodes are defined as sustained warming of the central and eastern tropical Pacific Ocean, thus resulting in

4536-532: Is one of Vanuatu's three official languages (together with English and French). The island is one of the most fertile in Vanuatu and produces kava , coffee , coconut , copra , and other fruits and vegetables. Recently, tourism has become more important, as tourists are attracted to the volcano and traditional culture. To help preserve the integrity of culture as a tourism asset, only local people are permitted to act as guides. There are various types of accommodation on

4662-529: Is set on the island, and was nominated for the Best Foreign Language Film at the 89th Academy Awards . The island is served by Whitegrass Airport . God is American , feature documentary (2007, 52 min), by Richard Martin-Jordan, on John Frum 's cult at Tanna. Island An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from

4788-497: Is the apple snail , initially introduced to the U.S. by aquarium owners. It has since been transported by hurricanes across the Gulf Coast and neighboring islands. These species compete for resources with native animals, and some may grow so densely that they displace other forms of existing life. For hundreds of years, islands have been created through land reclamation . One of the first recorded instances of this when people of

4914-628: Is the giant tortoise of the Seychelles , though it is unknown if it grew in size before or after reaching the island. Larger animals such as the hippopotamus tend to become smaller, such as in the case of the pygmy hippopotamus . This is known as insular dwarfism . In the case of smaller animals, it has been hypothesized that animals on islands may have fewer predators and competitors, resulting in selection pressure towards larger animals. Larger animals may exhaust food resources quickly due to their size, causing malnutrition in their young, resulting in

5040-517: Is the Bjerknes feedback (named after Jacob Bjerknes in 1969) in which the atmospheric changes alter the sea temperatures that in turn alter the atmospheric winds in a positive feedback. Weaker easterly trade winds result in a surge of warm surface waters to the east and reduced ocean upwelling on the equator . In turn, this leads to warmer sea surface temperatures (called El Niño), a weaker Walker circulation (an east-west overturning circulation in

5166-741: Is the centre of the Prince Philip movement , which reveres Prince Philip, Duke of Edinburgh , the late husband of Queen Elizabeth II . The cult is examined by British writer Matthew Baylis in his 2013 book Man Belong Mrs Queen: Adventures with the Philip Worshippers . Five men from the cargo cult were brought to the United Kingdom as part of the Channel 4 reality show Meet the Natives in 2007. Part of their itinerary included an off-screen meeting with

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5292-406: Is typically around 0.5 m (1.5 ft) higher than near Peru because of the buildup of water in the West Pacific. The thermocline , or the transitional zone between the warmer waters near the ocean surface and the cooler waters of the deep ocean , is pushed downwards in the West Pacific due to this water accumulation. The total weight of a column of ocean water is almost the same in

5418-529: The Atlantic Ocean in search of an alternate route to the East Indies . These historians theorize that successful explorers were rewarded with recognition and wealth, leading others to attempt possibly dangerous expeditions to discover more islands, usually with poor results. About 10% of the world's population lives on islands. The study of the culture of islands is known as island studies . The interest in

5544-518: The International Date Line and 120°W ), including the area off the west coast of South America , as upwelling of cold water occurs less or not at all offshore. This warming causes a shift in the atmospheric circulation, leading to higher air pressure in the western Pacific and lower in the eastern Pacific, with rainfall reducing over Indonesia, India and northern Australia, while rainfall and tropical cyclone formation increases over

5670-679: The John Frum cult remains strong on Tanna today, especially at Sulphur Bay in the southeast and Green Point in the southwest of the Island. The documentary Waiting for John (2015) by Jessica Sherry provides a history and overview of the current scene regarding these beliefs. A secessionist movement began in the 1970s, and the Nation of Tanna was proclaimed on 24 March 1974. While the British were more open to allowing its holdings in Vanuatu to achieve independence, it

5796-569: The Marshall Islands , and Tuvalu completely. Increases in the frequency and intensity of tropical cyclones can cause widespread destruction of infrastructure and animal habitats. Species that live exclusively on islands are some of those most threatened by extinction . An island is an area of land surrounded by water on all sides that is distinct from a continent. There is no standard of size that distinguishes islands and continents . Continents have an accepted geological definition – they are

5922-501: The Polynesians . Many of the previous island settlements required traveling distances of less than 100 km (62 mi), whereas Polynesians may have traveled 2,000–3,200 km (1,200–2,000 mi) to settle islands such as Tahiti . They would send navigators to sail the ocean without the aid of navigational instruments to discover new islands for settlement. Between 1100 and 800 BC, Polynesians sailed East from New Guinea and

6048-869: The Solomon Islands and reached the islands that make up the modern-day Fiji and Samoa . The furthest extent of this migration would be Easter Island in the East, and New Zealand in the South, with New Zealand's first settlements between 1250 and 1300. Historians have sought to understand why some remote islands have always been uninhabited, while others, especially in the Pacific Ocean , have long been populated by humans. Generally, larger islands are more likely to be able to sustain humans and thus are more likely to have been settled. Small islands that cannot sustain populations on their own can still be habitable if they are within

6174-493: The Solomon Islands created eighty such islands by piling coral and rock in the Lau Lagoon . One traditional way of constructing islands is with the use of a revetment . Sandbags or stones are dropped with a barge into the sea to bring the land level slightly out of the water. The island area is then filled with sand or gravel, followed by a construction of this revetment to hold it together. Islands have also been constructed with

6300-578: The Southern Ocean to the tropics in the East Pacific . The combination of the Humboldt Current and upwelling maintains an area of cooler ocean waters off the coast of Peru. The West Pacific lacks a cold ocean current and has less upwelling as the trade winds are usually weaker than in the East Pacific, allowing the West Pacific to reach warmer temperatures. These warmer waters provide energy for

6426-414: The lithosphere where the mantle is hotter than the surrounding area. These hotspots would give rise to volcanoes whose lava would form the rock the islands are made of. For some islands, the movement of tectonic plates above stationary hotspots would form islands in a linear chain, with the islands further away from the hotspot being progressively older and more eroded , before disappearing under

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6552-450: The sea as a natural barrier to the introduction of new species, causing the species that do reach the island to evolve in isolation. Continental islands share animal and plant life with the continent they split from. Depending on how long ago the continental island formed, the life on that island may have diverged greatly from the mainland due to natural selection . Humans have lived on and traveled between islands for thousands of years at

6678-474: The upward movement of air . As a result, the warm West Pacific has on average more cloudiness and rainfall than the cool East Pacific. ENSO describes a quasi-periodic change of both oceanic and atmospheric conditions over the tropical Pacific Ocean. These changes affect weather patterns across much of the Earth. The tropical Pacific is said to be in one of three states of ENSO (also called "phases") depending on

6804-522: The 16th century, European states placed most of Oceania in under colonial administration . Pohnpei was colonized by Spain as early as 1526. It changed hands from Germany to Japan to the United States before joining the Federated States of Micronesia in 1982, maintaining a "free association" status with the U.S. Guam was a Spanish territory until 1898, and now is a unincorporated territory of

6930-658: The 19th century. The first on record was the Rose in February 1804. The last known such visit was by the Sea Ranger in September 1871. Tanna was not a principal site of World War II , but about 1,000 people from Tanna were recruited to work on the American military base on Éfaté . Exposure to First World living standards may have led to the development of cargo cults . Many have died out, but

7056-569: The Bjerknes feedback naturally triggers negative feedbacks that end and reverse the abnormal state of the tropical Pacific. This perspective implies that the processes that lead to El Niño and La Niña also eventually bring about their end, making ENSO a self-sustaining process. Other theories view the state of ENSO as being changed by irregular and external phenomena such as the Madden–Julian oscillation , tropical instability waves , and westerly wind bursts . The three phases of ENSO relate to

7182-474: The Coastal Niño Index (ICEN), strong El Niño Costero events include 1957, 1982–83, 1997–98 and 2015–16, and La Niña Costera ones include 1950, 1954–56, 1962, 1964, 1966, 1967–68, 1970–71, 1975–76 and 2013. Currently, each country has a different threshold for what constitutes an El Niño event, which is tailored to their specific interests, for example: In climate change science, ENSO is known as one of

7308-603: The EP and CP types, and some scientists argue that ENSO exists as a continuum, often with hybrid types. The effects of the CP ENSO are different from those of the EP ENSO. The El Niño Modoki is associated with more hurricanes more frequently making landfall in the Atlantic. La Niña Modoki leads to a rainfall increase over northwestern Australia and northern Murray–Darling basin , rather than over

7434-492: The El Niño state. This process is known as Bjerknes feedback . Although these associated changes in the ocean and atmosphere often occur together, the state of the atmosphere may resemble a different ENSO phase than the state of the ocean or vice versa. Because their states are closely linked, the variations of ENSO may arise from changes in both the ocean and atmosphere and not necessarily from an initial change of exclusively one or

7560-491: The El Niños of 2006-07 and 2014-16 were also Central Pacific El Niños. Recent years when La Niña Modoki events occurred include 1973–1974, 1975–1976, 1983–1984, 1988–1989, 1998–1999, 2000–2001, 2008–2009, 2010–2011, and 2016–2017. The recent discovery of ENSO Modoki has some scientists believing it to be linked to global warming. However, comprehensive satellite data go back only to 1979. More research must be done to find

7686-541: The Equator, were defined. The western region is located over Indonesia and the eastern one over the equatorial Pacific, close to the South American coast. However, data on EQSOI goes back only to 1949. Sea surface height (SSH) changes up or down by several centimeters in Pacific equatorial region with the ESNO: El Niño causes a positive SSH anomaly (raised sea level) because of thermal expansion while La Niña causes

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7812-506: The Hawaiian islands being home to irrigated fields of taro, whereas in some islands, like Tahiti, breadfruit was more widely cultivated and fermented in order to preserve it. There is archeological evidence that Canary Islanders would chew the roots of ferns for sustenance, a practice that wore heavily on their molars . These islanders would also grow barley and raised livestock such as goats . Many island nations have little land and

7938-666: The Origin of Species . The first evidence of humans colonizing islands probably occurred in the Paleolithic era, 100,000 to 200,000 years ago. Reaching the Indonesian islands of Flores and Timor would have required crossing distances of water of at least 29 km (18 mi). Some islands, such as Honshu , were probably connected to the mainland with a land bridge that allowed humans to colonize it before it became an island. The first people to colonize distant oceanic islands were

8064-520: The Pacific Ocean and are dependent on agriculture and fishing. In climate change science, ENSO is known as one of the internal climate variability phenomena. Future trends in ENSO due to climate change are uncertain, although climate change exacerbates the effects of droughts and floods. The IPCC Sixth Assessment Report summarized the scientific knowledge in 2021 for the future of ENSO as follows: "In

8190-481: The U.S. The decolonization era saw many island states achieve independence or some form of self-governance . Nuclear weapons testing on the Marshall Islands left many atolls destroyed or uninhabitable, causing the forced displacement of people from their home islands as well as increases in cancer rates due to radiation . Colonization has resulted in a decline of observance of traditional cultural practices in places such as Hawaii, where Native Hawaiians are now

8316-453: The Walker circulation, which was named after Gilbert Walker who discovered the Southern Oscillation during the early twentieth century. The Walker circulation is an east-west overturning circulation in the vicinity of the equator in the Pacific. Upward air is associated with high sea temperatures, convection and rainfall, while the downward branch occurs over cooler sea surface temperatures in

8442-454: The West Pacific northeast of Australia averages around 28–30 °C (82–86 °F). SSTs in the East Pacific off the western coast of South America are closer to 20 °C (68 °F). Strong trade winds near the equator push water away from the East Pacific and towards the West Pacific. This water is slowly warmed by the Sun as it moves west along the equator. The ocean surface near Indonesia

8568-460: The West Pacific to a depth of about 30 m (90 ft) in the East Pacific. Cooler deep ocean water takes the place of the outgoing surface waters in the East Pacific, rising to the ocean surface in a process called upwelling . Along the western coast of South America, water near the ocean surface is pushed westward due to the combination of the trade winds and the Coriolis effect . This process

8694-429: The asymmetric nature of the warm and cold phases of ENSO, some studies could not identify similar variations for La Niña, both in observations and in the climate models, but some sources could identify variations on La Niña with cooler waters on central Pacific and average or warmer water temperatures on both eastern and western Pacific, also showing eastern Pacific Ocean currents going to the opposite direction compared to

8820-438: The atmosphere) and even weaker trade winds. Ultimately the warm waters in the western tropical Pacific are depleted enough so that conditions return to normal. The exact mechanisms that cause the oscillation are unclear and are being studied. Each country that monitors the ENSO has a different threshold for what constitutes an El Niño or La Niña event, which is tailored to their specific interests. El Niño and La Niña affect

8946-436: The atmospheric and oceanic conditions. When the tropical Pacific roughly reflects the average conditions, the state of ENSO is said to be in the neutral phase. However, the tropical Pacific experiences occasional shifts away from these average conditions. If trade winds are weaker than average, the effect of upwelling in the East Pacific and the flow of warmer ocean surface waters towards the West Pacific lessen. This results in

9072-406: The continent. For example, the presence of freshwater fish on an island surrounded by ocean would indicate that it once was attached to a continent, since these fish cannot traverse the ocean on their own. Over the course of time, evolution and extinction changes the nature of animal life on a continental island, but only once it splits from the mainland. An example is that of the southern beech ,

9198-591: The correlation and study past El Niño episodes. More generally, there is no scientific consensus on how/if climate change might affect ENSO. There is also a scientific debate on the very existence of this "new" ENSO. A number of studies dispute the reality of this statistical distinction or its increasing occurrence, or both, either arguing the reliable record is too short to detect such a distinction, finding no distinction or trend using other statistical approaches, or that other types should be distinguished, such as standard and extreme ENSO. Likewise, following

9324-543: The currents in traditional La Niñas. Coined by the Peruvian Comité Multisectorial Encargado del Estudio Nacional del Fenómeno El Niño (ENFEN), ENSO Costero, or ENSO Oriental, is the name given to the phenomenon where the sea-surface temperature anomalies are mostly focused on the South American coastline, especially from Peru and Ecuador. Studies point many factors that can lead to its occurrence, sometimes accompanying, or being accompanied, by

9450-451: The deposition of sediment by waves . These islands erode and grow as the wind and waves shift. Barrier islands have the effect of protecting coastal areas from severe weather because they absorb some of the energy of large waves before they can reach the shore. A fluvial island is an island that forms from the erosion and sedimentation of debris in rivers; almost all rivers have some form of fluvial islands. These islands may only be

9576-426: The distances and frequency with which invasive species may be transported to islands. Floodwaters from these storms may also wash plants further inland than they would travel on their own, introducing them to new habitats. Agriculture and trade also have introduced non-native life to islands. These processes result in an introduction of invasive species to ecosystems that are especially small and fragile. One example

9702-449: The dual concepts of space and time." The island is the centre of the John Frum religious movement, which attracts tourist interest as a cargo cult . The first John appeared at night as a spirit at a place called Green Point beach and told the people to return to their traditional way of life, or kastom. From that time kastom on Tanna has been seen as an alternative to the modernity encouraged by many missionary denominations. Yaohnanen

9828-461: The east. During El Niño, as the sea surface temperatures change so does the Walker Circulation. Warming in the eastern tropical Pacific weakens or reverses the downward branch, while cooler conditions in the west lead to less rain and downward air, so the Walker Circulation first weakens and may reverse.   The Southern Oscillation is the atmospheric component of ENSO. This component

9954-614: The eastern Pacific below average, and air pressure high in the eastern Pacific and low in the western Pacific. The ENSO cycle, including both El Niño and La Niña, causes global changes in temperature and rainfall. If the temperature variation from climatology is within 0.5 °C (0.9 °F), ENSO conditions are described as neutral. Neutral conditions are the transition between warm and cold phases of ENSO. Sea surface temperatures (by definition), tropical precipitation, and wind patterns are near average conditions during this phase. Close to half of all years are within neutral periods. During

10080-479: The eastern Pacific. However, in the 1990s and 2000s, variations of ENSO conditions were observed, in which the usual place of the temperature anomaly (Niño 1 and 2) is not affected, but an anomaly also arises in the central Pacific (Niño 3.4). The phenomenon is called Central Pacific (CP) ENSO, "dateline" ENSO (because the anomaly arises near the dateline ), or ENSO "Modoki" (Modoki is Japanese for "similar, but different"). There are variations of ENSO additional to

10206-404: The eastern equatorial part of the central Pacific Ocean will be lower than normal by 3–5 °C (5.4–9 °F). The phenomenon occurs as strong winds blow warm water at the ocean's surface away from South America, across the Pacific Ocean towards Indonesia. As this warm water moves west, cold water from the deep sea rises to the surface near South America. The movement of so much heat across

10332-621: The eastern portion of the country as in a conventional EP La Niña. Also, La Niña Modoki increases the frequency of cyclonic storms over Bay of Bengal , but decreases the occurrence of severe storms in the Indian Ocean overall. The first recorded El Niño that originated in the central Pacific and moved toward the east was in 1986. Recent Central Pacific El Niños happened in 1986–87, 1991–92, 1994–95, 2002–03, 2004–05 and 2009–10. Furthermore, there were "Modoki" events in 1957–59, 1963–64, 1965–66, 1968–70, 1977–78 and 1979–80. Some sources say that

10458-400: The ecological processes that take place on islands, with a focus on what factors effect the evolution , extinction , and richness of species. Scientists often study islands as an isolated model of how the process of natural selection takes place. Island ecology studies organisms on islands and their environment. It has yielded important insights for its parent field of ecology since

10584-718: The following years: Transitional phases at the onset or departure of El Niño or La Niña can also be important factors on global weather by affecting teleconnections . Significant episodes, known as Trans-Niño, are measured by the Trans-Niño index (TNI). Examples of affected short-time climate in North America include precipitation in the Northwest US and intense tornado activity in the contiguous US. The first ENSO pattern to be recognised, called Eastern Pacific (EP) ENSO, to distinguish if from others, involves temperature anomalies in

10710-534: The global climate and disrupt normal weather patterns, which as a result can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term surface cooling. Therefore, the relative frequency of El Niño compared to La Niña events can affect global temperature trends on timescales of around ten years. The countries most affected by ENSO are developing countries that are bordering

10836-409: The globe. Atlantic and Pacific hurricanes can have different characteristics due to lower or higher wind shear and cooler or warmer sea surface temperatures. La Niña events have been observed for hundreds of years, and occurred on a regular basis during the early parts of both the 17th and 19th centuries. Since the start of the 20th century, La Niña events have occurred during

10962-498: The habit of true warbler species) consumes spiders and insects that live on plants. Other examples of this phenomenon exist worldwide, including in Hawaii and Madagascar, and are not limited to island ecosystems. Species endemic to islands show a common evolutionary trajectory. Foster's rule (also known as the island rule), states that small mammals such as rodents evolve to become larger, known as island gigantism . One such example

11088-511: The higher altitude villages are known as kastom villages, where modern inventions are restricted, the inhabitants wear penis sheaths ( Bislama : nambas ) and grass skirts, and the children do not go to public school. According to anthropologist Joël Bonnemaison , author of "The Tree and the Canoe: history and ethnography of Tanna," their resistance to change derives from their traditional worldview and how they "perceive, internalise, and account for

11214-471: The internal climate variability phenomena. The other two main ones are Pacific decadal oscillation and Atlantic multidecadal oscillation . La Niña impacts the global climate and disrupts normal weather patterns, which can lead to intense storms in some places and droughts in others. El Niño events cause short-term (approximately 1 year in length) spikes in global average surface temperature while La Niña events cause short term cooling. Therefore,

11340-449: The island to become part of the newly independent nation of Vanuatu on 30 July 1980. Tanna and nearby Erromango were devastated by Cyclone Pam in March 2015, with reports of an unknown number of deaths, complete destruction of the island’s infrastructure and permanent shelters, and no drinking water. Following this, an El Niño -spurred drought further impacted on the people of Tanna. It is

11466-666: The island. In 2009 the Travel Channel aired Meet the Natives: USA , which brought five men from another group from Tanna to the United States . Their tribe reveres John Frum, an American World War II sailor who generations ago had taught the inhabitants to live in peace. The Tanna ambassadors were taken across, visiting five states, and eventually meeting former United States Secretary of State Colin Powell and verifying with him that

11592-454: The islands as a naturalist on HMS Beagle in 1835, as part of a five-year circumnavigation of Earth. He wrote that "the different islands to a considerable extent are inhabited by a different set of beings". Through the study of the finches and other animals he realized that organisms survive by changing to adapt to their habitat. It would be over twenty years before he published his theories in On

11718-468: The lake burst down the valley into Sulphur Bay , destroying the village with no loss of life. Mount Yasur is an accessible active volcano which is located on the southeast coast. Tanna was first settled about 400 BC by Melanesians from the surrounding islands. The glowing light of Mount Yasur attracted James Cook , the first European to visit the island, in August 1774, where he landed in an inlet on

11844-643: The largest landmass of a particular tectonic plate . Islands can occur in any body of water, including lakes , rivers , seas . Low-tide elevations , areas of land that are not above the surface during a high tide , are generally not considered islands. Islands that have been bridged or otherwise joined to a mainland with land reclamation are sometimes considered "de-islanded", but not in every case. The word island derives from Middle English iland , from Old English igland (from ig or ieg , similarly meaning 'island' when used independently, and -land carrying its contemporary meaning. Old English ieg

11970-427: The last several decades, the number of El Niño events increased, and the number of La Niña events decreased, although observation of ENSO for much longer is needed to detect robust changes. Studies of historical data show the recent El Niño variation is most likely linked to global warming. For example, some results, even after subtracting the positive influence of decadal variation, are shown to be possibly present in

12096-528: The long term, it is very likely that the precipitation variance related to El Niño–Southern Oscillation will increase". The scientific consensus is also that "it is very likely that rainfall variability related to changes in the strength and spatial extent of ENSO teleconnections will lead to significant changes at regional scale". The El Niño–Southern Oscillation is a single climate phenomenon that periodically fluctuates between three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases in

12222-404: The mainland, they had no need for boats. The motivation for island exploration has been the subject of research and debate. Some early historians previously argued that early island colonization was unintentional, perhaps by a raft being swept out to sea. Others compare the motivations of Polynesian and similar explorers with those of Christopher Columbus , the explorer who sailed westward over

12348-589: The majority of the local economy and built environment . These islands sometimes also require consistent foreign aid on top of tourism in order to ensure economic growth. This reliance can result in social inequality and environmental degradation . During tourism downturns, these economies struggle to make up the lost inflow of cash with other industries. Climate change threatens human development on islands due to sea level rise , more dangerous tropical cyclones , coral bleaching , and an increase in invasive species . For example, in 2017 Hurricane Maria caused

12474-598: The middle bush dialect in the central plateau of the island, which is very close to Lenakel Whitesands in the northeast near Whitesands . The five languages of Tanna feature among the most populous among all the indigenous languages of Vanuatu : These are grouped into the Tanna languages family, which is a subgroup of the South Vanuatu languages , a branch of the Oceanic languages . Many people on Tanna also speak Bislama , which

12600-472: The most populous island in Tafea Province , and one of the most populous islands in the country with a population of about 29,000 in 2009, which grew to 30,770 in 2015. Isangel , the provincial administrative capital, is on the west coast near the island's largest town of Lénakel . Tanna is populated almost entirely by Melanesians, and they follow a more traditional lifestyle than many other islands. Some of

12726-629: The neutral ENSO phase, other climate anomalies/patterns such as the sign of the North Atlantic Oscillation or the Pacific–North American teleconnection pattern exert more influence. El Niño conditions are established when the Walker circulation weakens or reverses and the Hadley circulation strengthens, leading to the development of a band of warm ocean water in the central and east-central equatorial Pacific (approximately between

12852-400: The observed phenomenon of more frequent and stronger El Niño events occurs only in the initial phase of the global warming, and then (e.g., after the lower layers of the ocean get warmer, as well), El Niño will become weaker. It may also be that the stabilizing and destabilizing forces influencing the phenomenon will eventually compensate for each other. The consequences of ENSO in terms of

12978-636: The oscillation which are deemed to occur when specific ocean and atmospheric conditions are reached or exceeded. An early recorded mention of the term "El Niño" ("The Boy" in Spanish) to refer to climate occurred in 1892, when Captain Camilo Carrillo told the geographical society congress in Lima that Peruvian sailors named the warm south-flowing current "El Niño" because it was most noticeable around Christmas. Although pre-Columbian societies were certainly aware of

13104-415: The other. Conceptual models explaining how ENSO operates generally accept the Bjerknes feedback hypothesis. However, ENSO would perpetually remain in one phase if Bjerknes feedback were the only process occurring. Several theories have been proposed to explain how ENSO can change from one state to the next, despite the positive feedback. These explanations broadly fall under two categories. In one view,

13230-515: The past, some societies were found to have lost their seafaring ability over time, such as the case of the Canary Islands , which were occupied by an indigenous people since the island's first discovery in the first century until being conquered by the Spanish Empire in 1496. It has been hypothesized that since the inhabitants had little incentive for trade and had little to any contact with

13356-417: The peruvian coast, and increased rainfall and decreased temperatures on its mountainous and jungle regions. Because they don't influence the global climate as much as the other types, these events present lesser and weaker correlations to other significant ENSO features, neither always being triggered by Kelvin waves , nor always being accompanied by proportional Southern Oscillation responses. According to

13482-483: The phenomenon, the indigenous names for it have been lost to history. The capitalized term El Niño refers to the Christ Child , Jesus , because periodic warming in the Pacific near South America is usually noticed around Christmas . Originally, the term El Niño applied to an annual weak warm ocean current that ran southwards along the coast of Peru and Ecuador at about Christmas time. However, over time

13608-539: The prince. In An Idiot Abroad , Series 2, Episode 1, Karl Pilkington visited Tanna and discussed the Prince Philip Movement and met those who visited Windsor Castle . Christian missionary John Gibson Paton served in Tanna in the mid 19th century. Cannibalism was practiced before Christianity swept the island. In the biography of Paton, the horror of the pagan practice of abusing and murdering disobedient wives

13734-406: The relative frequency of El Niño compared to La Niña events can affect global temperature trends on decadal timescales. There is no sign that there are actual changes in the ENSO physical phenomenon due to climate change. Climate models do not simulate ENSO well enough to make reliable predictions. Future trends in ENSO are uncertain as different models make different predictions. It may be that

13860-686: The same legal rights. El Ni%C3%B1o El Niño is associated with higher than normal air sea level pressure over Indonesia, Australia and across the Indian Ocean to the Atlantic . La Niña has roughly the reverse pattern: high pressure over the central and eastern Pacific and lower pressure through much of the rest of the tropics and subtropics. The two phenomena last a year or so each and typically occur every two to seven years with varying intensity, with neutral periods of lower intensity interspersed. El Niño events can be more intense but La Niña events may repeat and last longer. A key mechanism of ENSO

13986-399: The same meaning. Tanna is 40 kilometres (25 miles) long and 19 kilometres (12 miles) wide, with a total area of 550 square kilometres (212 square miles). Its highest point is the 1,084-metre (3,556-foot) summit of Mount Tukosmera in the south of the island. Siwi Lake was located in the east, northeast of the peak, close to the coast until mid-April 2000 when following unusually heavy rain,

14112-775: The sea entirely. An example is the Hawaiian Islands , with the oldest island being 25 million years old, and the youngest, Hawaii , still being an active volcano . However, not all island chains are formed this way. Some may be formed all at once by fractures in the tectonic plates themselves, simultaneously creating multiple islands. One supporting piece of evidence is that of the Line Islands , which are all estimated to be 8 million years old, rather than being different ages. Other island chains form due to being separated from existing continents. The Japanese archipelago may have been separated from Eurasia due to seafloor spreading ,

14238-406: The southeastern tip of the island that he named Port Resolution after his ship HMS Resolution . In the 19th century, traders and missionaries (chiefly Presbyterian ) arrived. The Tannese stuck to their traditions more strongly than other islands; there remain fewer Christians in comparison with the other islands of Vanuatu. Whaling vessels were some of the first regular visitors to the island in

14364-526: The spirit of peace taught by John Frum lives on in then US President, Barack Obama . While visiting with a family on Fort Stewart , US Army Major-General Tony Cucolo conferred a World War II Victory Medal and an Asiatic-Pacific Campaign Medal upon the chief in representation of the contribution the people of Tanna in World War II. Tanna , a film depicting the true story of a couple who decided to marry for love, rather than obey their parents' wishes,

14490-431: The strength of the trade winds was first identified by Jacob Bjerknes in 1969. Bjerknes also hypothesized that ENSO was a positive feedback system where the associated changes in one component of the climate system (the ocean or atmosphere) tend to reinforce changes in the other. For example, during El Niño, the reduced contrast in ocean temperatures across the Pacific results in weaker trade winds, further reinforcing

14616-549: The study of islands is due to their unique cultures and natural environments that differ from mainland cultures. This is for a few reasons: First, the obvious political and geographic isolation from mainland cultures. Second, unique restraints on resources and ecology creating marine-focused cultures with a focus on fishing and sailing. Third, a lasting historical and political significance of islands. The Polynesian diet got most of its protein from fishing. Polynesians were known to fish close to shore, as well as in deep water. It

14742-450: The surface. When these coral islands encircle a central lagoon , the island is known as an atoll . The formation of reefs and islands related to those reefs is aided by the buildup of sediment in shallow patches of water. In some cases, tectonic movements lifting a reef out of the water by as little as 1 meter can cause sediment to accumulate and an island to form. Barrier islands are long, sandy bars that form along shorelines due to

14868-521: The temperature anomalies and precipitation and weather extremes around the world are clearly increasing and associated with climate change . For example, recent scholarship (since about 2019) has found that climate change is increasing the frequency of extreme El Niño events. Previously there was no consensus on whether climate change will have any influence on the strength or duration of El Niño events, as research alternately supported El Niño events becoming stronger and weaker, longer and shorter. Over

14994-618: The term has evolved and now refers to the warm and negative phase of the El Niño–Southern Oscillation (ENSO). The original phrase, El Niño de Navidad , arose centuries ago, when Peruvian fishermen named the weather phenomenon after the newborn Christ. La Niña ("The Girl" in Spanish) is the colder counterpart of El Niño, as part of the broader ENSO climate pattern . In the past, it was also called an anti-El Niño and El Viejo, meaning "the old man." A negative phase exists when atmospheric pressure over Indonesia and

15120-438: The time of Charles Darwin . In biology, endemism is defined as the phenomenon where species or genus is only found in a certain geographical area. Islands isolate land organisms from others with water, and isolate aquatic organisms living on them with land. Island ecosystems have the highest rates of endemism globally. This means that islands contribute heavily to global biodiversity . Areas with high lives of biodiversity are

15246-452: The tropical Pacific Ocean. The low-level surface trade winds , which normally blow from east to west along the equator, either weaken or start blowing from the other direction. El Niño phases are known to happen at irregular intervals of two to seven years, and lasts nine months to two years. The average period length is five years. When this warming occurs for seven to nine months, it is classified as El Niño "conditions"; when its duration

15372-466: The west Pacific is abnormally high and pressure over the east Pacific is abnormally low, during El Niño episodes, and a positive phase is when the opposite occurs during La Niña episodes, and pressure over Indonesia is low and over the west Pacific is high. On average, the temperature of the ocean surface in the tropical East Pacific is roughly 8–10 °C (14–18 °F) cooler than in the tropical West Pacific . The sea surface temperature (SST) of

15498-441: The western and east Pacific. Because the warmer waters of the upper ocean are slightly less dense than the cooler deep ocean, the thicker layer of warmer water in the western Pacific means the thermocline there must be deeper. The difference in weight must be enough to drive any deep water return flow. Consequently, the thermocline is tilted across the tropical Pacific, rising from an average depth of about 140 m (450 ft) in

15624-561: The world. This is partly due to Mount Yasur , an active volcano and a major touristic attraction. It is also famous for its vibrant Melanesian culture , through dances and festivals. The island has also attracted the attention of many anthropologists for its cargo cults . The name Tanna , first cited by James Cook , is derived from the word tana in the Kwamera language , meaning "earth". Etymologically, Tanna goes back to Proto-Oceanic * tanoq , from Proto-Malayo-Polynesian * taneq , with

15750-579: Was opposed by the French colonists and finally suppressed by the Anglo-French Condominium authorities on 29 June 1974. In 1980, there was another attempt to secede, declaring the Tafea Nation on 1 January 1980, its name coming from the initials of the five islands that were to be part of the nation (Tanna, Aniwa , Futuna , Erromango and Aneityum ). British forces intervened on 26 May 1980, allowing

15876-470: Was reported that Rapa Nui people were known to fish as far as 500 km (310 mi) from shore at coral reefs. Spear , line , and net fishing were all used, to catch tuna as well as sharks and stingrays . Island cultures also cultivate native and non-native crops. Polynesians grew the native yam , taro , breadfruit , banana , coconut and other fruits and vegetables. Different island climates made different resources more important, such as

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