Papua New Guinea
Wallis and Futuna
Oceania is the collective name for the vast accumulation of
islands and atolls in the central and western parts of the Pacific
Ocean. The borders of Oceania are arbitrary. The island of New
Guinea is considered to be the western border, Easter Island is the
eastern border. As a rule, Oceania does not include Australia, as
well as the islands and archipelagos of Southeast Asia, the Far East
and North America. In the section of geography, country studies,
Oceania is studying an independent discipline - ocean studies.
Oceania is the world's largest cluster of islands located in the southwestern and central parts of the Pacific Ocean, between the subtropical latitudes of the Northern and temperate Southern Hemispheres. When all land is divided into parts of the world, Oceania is usually united with Australia into a single part of the world, Australia and Oceania, although sometimes it stands out as an independent part of the world.
Geographically, Oceania is divided into several regions: Micronesia (in the north-west), Melanesia (in the west), and Polynesia (in the east); New Zealand is sometimes singled out.
The total area of the islands of Oceania, the largest of which is New Guinea, is 1.26 million km² (together with Australia 8.52 million km²), the population is about 10.7 million people. (together with Australia 32.6 million people). Excluding Australia, Oceania in terms of total area and total population is comparable to the African state of Chad.
The islands of Oceania are washed by numerous Pacific seas (Coral Sea, Tasman Sea, Fiji Sea, Koro Sea, Solomon Sea, New Guinea Sea, Philippine Sea) and Indian Oceans (Arafura Sea).
Equator and the international date line pass through Oceania. It is a broken line, most of which runs along the 180 ° meridian.
Across the whole of Oceania, along the equator, are the warm Northern Passat and Southern Passat currents and the Passat countercurrent. In the southwestern part of Oceania, a warm East Australian Current passes. Characteristic of Oceania is the absence of cold sea currents (with the exception of the Pacific Ocean region southeast of New Zealand), which largely determines the climate of this region.
In terms of geology, Oceania is not a continent: only Australia, New Caledonia, New Zealand, New Guinea and Tasmania are of continental origin, having formed on the site of the hypothetical mainland of Gondwana. In the past, these islands constituted a single land, however, as a result of sea level rise, a significant part of the surface was under water. The relief of these islands is mountainous and strongly dissected. For example, the highest mountains of Oceania, including Mount Jaya (5029 m), are located on the island of New Guinea.
Most of the islands of Oceania are of volcanic origin: some of them are peaks of large submarine volcanoes, some of which still exhibit high volcanic activity (for example, the Hawaiian Islands).
Other islands are of coral origin, being atolls that formed as a result of the formation of coral buildings around volcanoes submerged under water (for example, Gilbert Islands, Tuamotu). A distinctive feature of such islands are large lagoons, which are surrounded by numerous islands, or motu, whose average height does not exceed three meters. In Oceania, there is an atoll with the largest lagoon in the world - Kwajalein in the Marshall Islands archipelago. Despite the fact that its land area is only 16.32 km² (or 6.3 sq. Miles), the lagoon area is 2174 km² (or 839.3 sq. Miles). The largest atoll in terms of land area is Christmas Island (or Kiritimati) in the Line archipelago (or Central Polynesian Sporades) - 322 km². However, among the atolls there is also a special type — the elevated (or elevated) atoll, which is a limestone plateau up to 50-60 m above sea level. This type of island has no lagoon or there are traces of its past existence. Examples of such atolls are Nauru, Niue, Banaba.
The relief and geological structure of the bottom of the Pacific Ocean in the region of Oceania has a complex structure. From the Alaska Peninsula (which is part of North America) to New Zealand, there are a large number of hollows of the marginal seas, deep-sea ocean trenches (Tonga, Kermadek, Bougainville), which form a geosynclinal belt characterized by active volcanism, seismicity, and a contrasting relief.
There are no minerals on most islands of Oceania, only the largest of them are under development: nickel (New Caledonia), oil and gas (New Guinea island, New Zealand), copper (Bougainville island in Papua New Guinea), gold (New Guinea , Fiji), phosphates (on most islands, deposits are almost or already developed, for example, in Nauru, on the islands of Banaba, Makatea). In the past, active development of guano, decomposed seabird droppings, which was used as nitrogen and phosphorus fertilizer, was carried out on many islands of the region. On the ocean floor of the exclusive economic zone of a number of countries, there are large accumulations of iron-manganese nodules, as well as cobalt, however, at the moment, no development is being carried out due to economic inexpediency.
Oceania is located within several climatic zones: equatorial, subequatorial, tropical, subtropical, temperate. Most of the islands have a tropical climate. The subequatorial climate dominates the islands near Australia and Asia, as well as east of 180 meridian in the equatorial zone, the equatorial climate west of 180 meridian, subtropical - north and south of the tropics, temperate - on most of the South Island in New Zealand.
The climate of the islands of Oceania is determined mainly by the trade winds, therefore, most of them have heavy rainfall. The average annual rainfall varies from 1,500 to 4,000 mm, although on some islands (in particular, due to the topography and the leeward side), the climate may be more arid or more humid. Oceania has one of the wettest places on the planet: up to 11,430 mm of precipitation falls annually on the eastern slope of Mount Waiaaleale on the island of Kauai (the absolute maximum was reached in 1982: then 16,916 mm fell). Near the tropics, the average temperature is about 23 ° C, at the equator - 27 ° C, with a slight difference between the hottest and coldest months.
The climate of the islands of Oceania is also greatly affected by such anomalies as the El Niño and La Niña currents. During El Niño, the intertropical convergence zone moves north towards the equator, while at La Niña it moves south towards the equator. In the latter case, the islands experience severe drought; in the former, heavy rains.
Most islands in Oceania are subject to the devastating effects of
natural disasters: volcanic eruptions (Hawaiian Islands, New
Hebrides), earthquakes, tsunamis, cyclones, accompanied by typhoons
and heavy rains, droughts. Many of them lead to significant material
and human losses. For example, the tsunami in Papua New Guinea
killed 2200 people in July 1999.
There are glaciers high in the mountains on the South Island in New Zealand and on the island of New Guinea, however, due to the process of global warming, their area is gradually decreasing.