Unit 10: Oceania
The region of Oceania includes Australia, New Zealand, the islands of the South Pacific, Antarctica, and the world's oceans. This vast area has few human settlements compared to the other regions, but its physical geography is affected by human activities all over the world.
Oceania shares several themes with the other regions, including colonialism, urbanization, globalization, and human-environmental interaction. Since the region is dominated by water, it includes issues of territorial claims over the world's oceans. Antarctica is also the subject of international claims. Australia and New Zealand have flora and fauna found nowhere else on Earth.
There has been little industrial development in the South Pacific. Most of the islands in the South Pacific were claimed or colonized by the imperial powers of Europe, Japan, and the United States. They are considered peripheral to the overall global economy. Tourism is the major activity in the South Pacific, and research is the major activity in Antarctica. Both areas have opportunities for greater economic development in the future.
Oceania is uniquely affected by climate change. Rising temperatures melt the polar caps, which in turn contribute to rising sea levels. Changes in precipitation patterns seriously affect the biodiversity of tropical islands in the Pacific, and changes in temperature affect agricultural activity and tourism.
We explore the physical geography of this region by introducing its sub-regions before you read about them in the text: Australia and New Zealand, Micronesia, Melanesia, Polynesia, and Antarctica.
This is a particularly difficult region to characterize due to its vast extent and the diversity of its physical geography. We begin with Australia and New Zealand because they dominate the region in terms of population. We move to the Pacific Islands and consider them as a group even though they are separated by great ocean distances. In spite of this separation, they have many characteristics in common and share many of the same challenges. Finally, we explore Antarctica separately because it is a continent like no other. As the coldest continent on Earth, with no permanent human habitation, Antarctica is one of the world's remaining frontiers.
Completing this unit should take you approximately 5 hours.
Upon successful completion of this unit, you will be able to:
- describe how the different landscapes in Oceania relate to their distance from tectonic plate boundaries and factors that have contributed to their high levels of biodiversity;
- explain how political struggles among members of the international community have influenced Antarctica and the world's oceans;
- relate the dynamic nature of the polar regions to climate change, including how the physical attributes of the countries in Oceania affect their ability to respond;
- describe the factors contributing to Oceania's varied degrees of urbanization, economic activities, and patterns of settlement;
- summarize the human geography of Oceania before and after colonialism and the role isolation plays in the region in terms of global connectivity; and
- summarize the main environmental concerns of the Pacific islands, including how different types of islands respond to the effects of climate change.
10.1: Maps of Oceania
Let's begin our examination of Oceania by studying some maps of the region.
Study these maps of Australia and New Zealand, the Pacific, and Antarctica so that you are familiar with the locations of the countries, cities, and some of the major water bodies.
10.2: The Physical Geography of Australia and New Zealand
Australia is an island, country, and continent – it is the smallest and only island continent. Australia is a large mainland and includes the island of Tasmania to the south. The Indian Ocean surrounds Australia's western and southern coasts. Indonesia and Papua New Guinea lie to the north, separated by the Timor Sea and the Arafura Sea. The Gulf of Carpentaria extends to the north along Australia's eastern coast, almost reaching Papua New Guinea.
The Great Barrier Reef runs for more than 2,575 km off the continent's northeastern shores, with the Coral Sea, which separates the Great Barrier Reef from the South Pacific. The Great Australian Bight, an open bay, and the island of Tasmania are on the southern side of Australia. Australia is tectonically stable and is the flattest of the continents, with low-relief deserts, grassy plateaus, and scrublands that dominate its interior.New Zealand has two main islands – the North Island and South Island, separated by the Cook Strait – and more than 700 small islands. The Tasman Sea separates New Zealand from Australia.
While we often group New Zealand with Australia, its tectonic setting and landforms are really quite different. The country is tectonically active, with rugged coastlines, mountain ranges, and volcanoes. Many consider it part of Polynesia. New Zealand experiences frequent and intense earthquakes since it is located along the southwest rim of the Pacific Ring of Fire. Although there is evidence of past volcanism throughout New Zealand, the only active volcanoes are on the North Island and the smaller, outlying islands.
For those who reside in the northern hemisphere, remember that December, January, and February are summer months for Australia and New Zealand because they are in the southern hemisphere. Their winter months are in June, July, and August. Although their latitudinal locations are similar, the climates of Australia and New Zealand are quite different.
Australia's larger landmass makes its temperatures more extreme than New Zealand's (See Figure 10.1 and Figure 10.2). Australia is dominated by arid to semi-arid climates in the west and interior. It becomes more temperate as you approach the east coast. Since the northernmost tip of Australia, Cape York, is just 10° south of the Equator, Australia's northern coast experiences tropical conditions.
Temperate climates prevail in New Zealand. Snow falls on the South Island in the winter and at higher elevations on the North Island. The west coasts of New Zealand receive more rain than the east coasts due to the rain shadow effect of the Southern Alps.
10.3: The Physical Geography of Melanesia, Micronesia, and Polynesia
Hundreds of islands surrounded by the Pacific Ocean comprise the three island groups of the South Pacific: Melanesia, Micronesia, and Polynesia. These three groups make up the largest geographic area in the world and are grouped according to their physical geography, local inhabitants, and location.
All three groups are vulnerable to natural disasters, which are particularly difficult to respond to given their remote locations. Evacuation and repair efforts are severely hampered.Melanesia, shown in Figure 10.3, includes Papua New Guinea, the largest country in the Pacific Islands. Papua New Guinea shares the island of New Guinea with Indonesia. All of the countries in Melanesia are independent except for New Caledonia, which is still under French control.
Melanesia is tectonically active like the insular countries of East and Southeast Asia. Active volcanoes, earthquakes, and tsunamis are common in Melanesia. Figure 9.3 in Section 9.2 shows how close Melanesia and the other island groups are to the Pacific Ring of Fire.- Mount Wilhelm, or Enduwa Kombuglu, the highest peak in the mountains of Papua New Guinea, reaches 4,509 meters. At that elevation, Mount Wilhelm and some of the other mountains occasionally receive snow despite their proximity to the Equator.
Tropical forests cover most of Papua New Guinea and the islands of Melanesia. Figure 10.4 shows the tropical forests in Fiji's highlands. - Micronesia is east of the Philippines and north of Indonesia and Melanesia (see Figure 10.5). Most of Micronesia's islands are low islands composed of coral. Some, such as the Mariana Islands, are high islands of volcanic origin.
The Mariana Island archipelago is divided into two jurisdictions: the northern part is the U.S. Commonwealth of the Northern Mariana Islands, and the southern part is the U.S. territory of Guam. The northern islands are volcanic (see Figure 10.6). The Mariana Islands were formed by the subduction of the Pacific plate by the Mariana plate (note geographers say Mariana and Marianas interchangeably). It also created the Mariana Trench, the deepest part of the Earth's oceans and the lowest part of the surface of the Earth's crust. The maximum known depth of the Mariana Trench is 10,984 meters, which exceeds the elevation of Mount Everest by more than 2,000 meters.
Vegetation on the islands of Micronesia depends on whether it is a high island or a low island. The volcanic islands have rich soils that can support a variety of vegetation, while the coral islands have much poorer soils. Figure 10.7 shows the coral island of Nauru.Polynesia covers much of the mid- and southern Pacific Ocean (see Figure 10.8). Composed of more than 1,000 islands, Polynesia includes islands with high mountains, such as Hawai'i, and low-lying coral atolls, such as some of the Tongan islands. The islands that have mountains with elevations high enough to condense moisture from the clouds receive adequate precipitation. However, the low-elevation islands lack this ability and suffer from shortages of fresh water, making human settlement a challenge.
Many volcanic islands in Polynesia occur in the interior of a tectonic plate rather than along a plate boundary. These are hotspot volcanoes. A hotspot is a large plume of hot mantle material that rises from deep within the Earth.
A line of volcanoes develops as a tectonic plate moves over a hotspot (see Figure 10.9). The plate continues to move, but the hotspot remains in the same place. When a volcano moves away from an oceanic hotspot, it starts to erode and is eventually no longer visible above the surface of the water.Watch this animation to see how volcanoes form over a hotspot and eventually submerge as the plate moves over the hotspot.
Volcanoes developed on the Hawaiian islands as the Pacific plate moved over a hotspot (see Figure 10.10). The only active volcanoes are on the islands of Hawaii and Maui. Kīlauea is the youngest and most active, followed by Mauna Loa, which is the largest volcano on Earth. Only two more volcanoes are active in Hawaii: Hualālai and Mauna Kea. Haleakalā is the only remaining volcano on Maui. Kama'ehuakanaloa is the only known active Hawaiian submarine volcano – it is labeled Lō'ihi in Figure 10.10.
As the Pacific plate continues to move, Kama'ehuakanaloa will break the surface of the water. These are shield volcanoes rather than the stratovolcanoes introduced in Section 9.3. Consequently, the Hawaiian island volcanoes are much less explosive. They are characterized by thin lava flows that cover large areas rather than pyroclastic flows.
10.4: The Physical Geography of Antarctica
Nearly all of Antarctica rests south of the Antarctic Circle. South America is its closest continent. Antarctica is a desert because it receives so little annual precipitation. Because it is so cold, the small amount of snow that falls rarely melts. Eventually, this snow compresses the layers of snow below, forcing it to recrystallize into granules that become denser as the air space between the grains decreases.
Freshly-fallen snow has a density of 50 to 70 kg m-3. Firn, or partially compacted snow that has no pore space remaining between the flakes or crystals, has a density of 400 to 830 kg m-3. Glacial ice has a density of 830 to 923 kg m-3. This process takes more than a hundred years (see Figure 10.11). Figure 10.12 shows a cross-section with snow at the top, blue glacial ice at the bottom, and firn in between.
Although Antarctica began icing about 45.5 million years ago, scientists have only been able to extract samples dating 800,000 years old. The terrain below Antarctica's ice sheet is mountainous – it has the highest average elevation of any continent in the world at 2,500 meters.
The Transantarctic Mountains, one of the longest mountain ranges on Earth, bisects Antarctica. Some of its peaks have elevations higher than 4,500 meters above sea level and are ice-free. The Ellsworth Mountains to the west of the Transantarctic range include Mount Vinson, the highest point on the continent at 4,900 meters.
Volcanoes which are likely due to the West Antarctic Rift System, exist under Antarctica's ice sheet. These volcanoes, including Mount Erebus, exist where the Antarctic tectonic plate is thinning. This is similar to the tectonic activity we saw along the East African Rift. See Figure 10.13 to study the locations of these features.Read this text, which introduces some of the parts of the vast region of Oceania.
Figure 10.14 shows that Australia was once part of the supercontinent Pangaea. The southern portion of Pangaea (known as Gondwana or Gondwanaland) dominated the southern hemisphere. About 180 million years ago, Gondwanaland broke up to form the landmasses of Africa, South America, the Indian subcontinent, the Arabian Peninsula, Antarctica, Australia, and New Zealand. Consequently, any species that lived together on these landmasses were separated and evolved independently.
Figure 10.14 also shows the stages of the break up of the supercontinents and their drift to their present locations. Australia and New Zealand were particularly isolated given their distance from other landmasses and the length of time they have been separated. Tectonic stability in Australia, climate patterns, and other factors over geologic time have contributed to the high number of unique species on the continent. Scientists estimate that more than 80% of Australia's mammals are not found anywhere else in the world. Although many of Australia's and New Zealand's species are descendants of those that existed on Gondwana, some flew there, floated there, or were brought by humans.Wallace's and Weber's Lines (see Figure 10.15) are hypothetical lines geographers have drawn to separate biogeographical realms. Some call these lines "faunal boundaries". The naturalist Alfred Russel Wallace created a line to separate the species of Asian and Austral origin between Borneo and Sulawesi and between Bali and Lombok.
Max Carl Wilhelm Weber, a biogeographer and zoologist, believed the boundary between the species was farther east, between Sulawesi and Buru, coming much closer to the island of New Guinea and the continent of Australia.
During the ice ages, colder global temperatures meant that glaciers could advance, and sea levels were lower. Consequently, animals were able to cross from one landmass to another across land bridges. However, the continental shelf may have been too deep for animals to cross in some locations. For example, we only find Marsupials on the Austral side because they were unable to cross to the Asian side.
10.5: The World's Oceans and Polar Frontiers
Let's consider the oceans in terms of international territorial control and the claims countries have made on the territories that are part of this region. Many are interested due to its fossil fuel resources.
Watch this video for a description of the extreme weather conditions Ben Saunders and fellow explorer Tarka L'Herpinieres experienced for 105 days when they retraced Captain Robert Falcon Scott's 1,800-mile expedition to the South Pole.
Saunders recounts this trek on the coldest, windiest, and highest-altitude continent on the planet. However, he recounts that reaching his destination at the South Pole was anticlimactic because it houses a well-equipped research station (see the Amundsen-Scott Research Station in Figure 10.16).
Getting to Antarctica and traveling between these research stations is treacherous, even when you are not traveling on foot. Most researchers approach Antarctica from South America or the Falkland Islands by plane or ice breaker ship. Equipment is usually shipped to one of the research stations in advance.
Once in Antarctica, most scientists travel to field sites by plane (like the De Havilland Twin Otter), snowmobile, or on vehicles modified for the conditions. Since many parts of Antarctica are protected, no vehicles are allowed to enter – researchers must drag their supplies to the field on sleds.Read this text to learn more about the human interest in this landscape.
This map shows the Amundsen-Scott Research Station at the South Pole in Antarctica.
Scientists come to Antarctica from all over the world. Many are based at research stations like the Amundsen-Scott facility and collect data from great distances.
Watch this video where Dustin Schroeder, a geophysicist from Stanford University, describes his work capturing data on rising sea levels. He uses radar technology to study the subglacial and englacial (inside a glacier) conditions of Antarctica's rapidly changing ice sheets.Researchers use ice cores to study the ice sheets and climate conditions of Antarctica. In Figure 10.17, a scientist uses an auger to drill into the ice sheet to retrieve a shallow ice core like the one shown in Figure 10.18.
Watch this video to learn about a drilling project that retrieved ice deposited as snow 115,000 to 130,000 years ago.
In addition to global navigation satellite system (GNSS) surveys and ice-flow modeling, scientists use radar to locate drill sites, such as the Hercules Dome near the Thiel Mountains, as shown in Figure 10.13. The best locations for drilling are at ice divides because researchers can avoid disturbances associated with horizontal ice movement. Like a drainage divide, this is where the ice flows in opposite directions, as shown in Figure 10.19.
10.6: Human Settlement and Economic Activity in Oceania
Let's return to Australia, New Zealand, and the Pacific islands to explore the settlement patterns and economic activities that developed. We will not include Antarctica since it does not have a permanent population.
Read this text, which introduces the region's indigenous populations, European colonization, patterns of human settlement, and economic development.
Like the indigenous populations in the United States and Canada, the Australian Aboriginals and Māori were subject to assimilation and became (and were treated) like minorities in their native lands. For example, they took children from their families and communities, prohibited them from learning and speaking their language, forced them to assimilate into European customs, and confiscated Aboriginal and Māori lands for their own.
Read this article where the descendant of an Irish immigrant describes how his grandfather seized the Māori land for himself.Australia's Human Rights Commission and New Zealand's Ministry of Justice have created truth and reconciliation inquiries to settle claims and pay reparations to those affected by government assimilation policies. In addition to discriminating against the indigenous population, Australia implemented the White Australia Policy.
The Immigration Restriction Act of 1901 sought to "keep" Australia "British". It subsidized the relocation of British citizens to Australia and limited the immigration of non-Whites, particularly Asians. New Zealand adopted a similar policy for the same reasons. By the 1970s, both countries eliminated these policies.
While most of Australia's population is White with British ancestry, new immigrants account for nearly 30% of Australia's population, the highest proportion among Western countries. The thematic map in
Figure 10.20 shows the number of immigrants from each country. Most are from the United Kingdom, China, and New Zealand. Fewer than three percent of the population is Aboriginal.
New Zealand has experienced a nearly identical situation. Most of their population is also White with British ancestry. In 2018 nearly one-third of New Zealand's population was born outside New Zealand. Nearly one-fourth of the immigrants are from the United Kingdom, followed by China, India, Australia, South Africa, Fiji, and Samoa. Fewer than 17% of the population is Māori.Figure 10.21 traces the pattern of urban development along Australia's coast due to British colonization. From 1787–1868, Britain shipped its convicts to Australia to alleviate its overcrowded prisons. Sydney of New South Wales was its first penal colony. The British also created penal colonies in Brisbane in Queensland, Perth in Western Australia, and other locations. Many Australians can trace their lineage to these transported convicts.
The coastal cities anchor Australia's two core areas. The Western Core Area is anchored by the city of Perth, and the Eastern Core Area is anchored by the capital, Canberra, and the cities of Brisbane, Sydney, Melbourne, and Adelaide. The inland areas that buffer Australia's core form the peripheral regions, which provide the food, raw materials, and other goods needed to support the core regions. Nearly 70% of Australia's population lives in these urbanized regions rather than in the interior.
Great Britain took advantage of Australia's natural resources when the British government and private interests seized and converted Aboriginal land into agricultural and mining operations. Several gold rushes in South Australia during the mid-19th century brought immigrants from Europe, North America, and China. Miners also discovered silver, lead, and copper in the region. However, these newcomers never compensated the Aboriginal people for the land they stole, which the Aborigines had lived on for more than 25,000 years.New Zealand's population is also coastal (see Figure 10.22). The Digital Elevation Model (DEM) of New Zealand in Figure 10.23 shows South Island is dominated by the Southern Alps, which explains why it has such a low population density. The Southern Alps are along the convergent boundary between the Australian and Pacific tectonic plates.
Generally, the Pacific islands are not densely populated. They are about 35 percent urbanized, but, like many other developing sub-regions, they are undergoing rapid urbanization. Birth rates are high, and the relatively young populations are seeking job opportunities beyond agriculture and fishing.
Read this article to learn how the COVID-19 pandemic wreaked economic havoc on the Pacific island countries in addition to the illness and death residents experienced. The Pacific island economies suffered from the downturn in tourism, which has become a major source of revenue due to the island's attractive climate and sunny beaches. The population has become increasingly dependent on tourism in the core regions.
Overfishing due to human population growth has depleted the fishing industry, which has long supported the economies of the Pacific Islands. Some islands have natural resources, such as the phosphates mined on the Micronesian island of Nauru.Several islands and archipelagos are under the jurisdiction of the United States, France, the United Kingdom, and New Zealand due to their strategic locations in the Pacific Ocean. Thus, western culture has significantly influenced the traditional cultures of Guam, the Northern Mariana Islands, Wake Island, American Samoa, the Hawaiian Islands, New Caledonia, French Polynesia, Pitcairn Islands, and the Cook Islands.
Although they continue to be remote, the islands of the Pacific are not as isolated as they once were. Modern technology has promoted globalization even among the independent countries of the Pacific Island realm. This physical connectedness was demonstrated on Jan. 15, 2022, when the Hunga Tonga volcano erupted and triggered a Pacific-wide tsunami that killed five people and caused significant damage to many coastal communities in the Tonga island groups of Ha`apai and Tongatapu (see Animation 10.1).The volcanic eruption severed the undersea cable that connects Tonga to the internet. Tonga is one of many Pacific islands that has only one undersea cable to provide internet service to its residents. The world only learned what had occurred one week after the eruption. The undersea cable took more than a month to repair, while Tonga had to rely on its satellite connections.
Read this article, where Karen Scott complains that the United Nations Convention on the Law of the Sea (UNCLOS) signed in 2016 inadequately addresses these issues. Several key countries have not yet ratified UNCLOS. For example, the United States, which has yet to sign, says it will abide by the regulations but is not legally bound to do so.
10.7: Oceania's Environmental Challenges
Oceania's low-lying Pacific islands are vulnerable to sea level rise caused by the melting polar regions. Climate change also threatens the oceans and their ecosystems as our oceans become more acidic due to increased atmospheric carbon dioxide (acidification). Rising water temperatures cause our coral reefs to bleach.
Mineral extraction, deforestation, and overgrazing are also degrading the environment of Oceania. Invasive species are depleting the biodiversity of this region.
Surrounded by salt water, the islands of the Pacific must rely on rainfall to replenish their freshwater resources. However, the population on many of these islands is increasing and straining freshwater supplies. Meanwhile, the world's garbage is polluting the oceans and washing ashore on Pacific islands.Read this section for more information on these environmental challenges.
Kiribati, an island group that spans 3.5 million km2 of the Pacific Ocean and extends into Polynesia and Micronesia, is at high risk if sea levels rise. Interestingly, Kiribati is the only country with land in all four hemispheres: north and south of the equator and on both sides of the 180° meridian. Figure 10.25 shows the extent of Kiribati and the shift of the International Dateline so all of Kiribati's islands are in the same day.
Although Kiribati's islands are atolls (or coral islands in the case of Banaba), the risks associated with sea level rise are not limited to being submerged by ocean waves. Encroaching seawater threatens freshwater resources and increases soil salinization, which destroys arable land.
Some argue the atoll and reef islands may be able to adjust if the sea level rises slowly – coral polyp activity will continue to occur, and the reef will rise in accordance with the sea level. However, the rise could be catastrophic if it is too rapid and outpaces coral polyp activity. In addition, ocean acidification causes coral bleaching that will inhibit or kill reef growth.
The situation in Kiribati is precarious, even in the best-case scenario. In 1999, the ocean completely inundated two of its small, uninhabited islands.
Watch this video where Anote Tong, president of Kiribati in 1915, discusses climate change and the fate of his country.The continent of Antarctica is also vulnerable to climate change. Polar scientist Ted Scambos notes that the activity of Antarctica's ice sheets above the surface only indicates more dramatic occurrences below. An ice sheet grounded below sea level can destabilize quickly once it begins to melt or thin. The embedded animation illustrates how quickly Antarctica's ice mass has decreased during the past 20 years, particularly since 2006. The embedded video illustrates how this acceleration is occurring.
Because seawater is denser than ice, ice sheets with ice below sea level only remain where they are because of their own weight. Once the ice starts to thin, it no longer exceeds the mass of the seawater, and the grounding line (or grounding zone) is pushed back. The ice sheet is now thicker at the new location of the grounding line; if the underlying bedrock's slope is great enough, the ice flow increases. This is what has occurred in the case of Thwaites Glacier.
Eventually, the overlying ice may no longer be heavy enough to keep the ice below sea level from lifting off the ground. When it does, water penetrates beneath the ice sheet. Consequently, more ice breaks off into the ocean and, over time, melts in the warmer seawater. Since this causes the ice sheet to lose mass, the grounding line is pushed back even more, and this self-reinforcing mechanism causes instability.
Read this article. Be sure to watch the embedded animation and video.In addition to the loss of polar ice and rising sea levels, Finlayson cites other examples of environmental degradation that continue to plague the Pacific Islands. For example, during World War II, troops from Japan, the United States, and New Zealand all used islands in the Pacific. Guam, Hawaii, Fiji, and New Caledonia have been particularly affected by deforestation, ordnance dumping, and the introduction of invasive species, among other forms of environmental damage.
Figure 10.26 shows unexploded World War II ordnances found on the Peleliu Island of Palau. Residents of these islands still die from unexpected explosions from bombs buried underground.
After World War II, several countries used islands in the Pacific to test their nuclear weapons during the Cold War. For example, the United States detonated nuclear weapons in eastern Micronesia on the Bikini Atoll, which is part of the Marshall Islands. Radioactive fallout remains a concern there and in other areas where the United Kingdom and France tested nuclear weapons.
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