Oceania

Open ocean, flocking seabirds, and thousands of islands, from low-lying atolls to high mountains, spanning across an enormous area of Earth, called Oceania. In the 18th century, Captain James Cook asked, “how shall we account for this nation having spread itself to so many detached islands so widely disjoined from each other in every quarter of the Pacific Ocean?” Magellan, another European explorer, echoed a similar sentiment, stating, "a sea so vast the human mind can scarcely grasp it." The indigenous people of the Pacific, however, were used to a world of water. Tongan and Fijian intellectual and writer, Epeli Hauʻofa, described how the indigenous people of this region viewed their world as more than just islands, Hauʻofa writes:

“Their universe comprised not only land surfaces, but the surrounding ocean as far as they could traverse and exploit it, the underworld with its fire-controlling and earth-shaking denizens, and the heavens above with their hierarchies of powerful gods and named stars and constellations that people could count on to guide their ways across the seas” (pg.152).

“People raised in this environment were at home with the ocean” (Hauʻofa, pg.153). To the indigenous people, this is the region where water connects people more than land. In contrast to common Western views, Melanesians, Micronesians, and Polynesians have long considered Oceania to be a “ sea of islands ” rather than “islands in a far sea.” Characterizing Oceania as a "sea of islands" better reflects Pacific Islander life through the interconnectedness and relationships between remote islands made possible by hundreds of years of ancient navigation, trade, and communication. The latter views Oceania as small states separated by the vast ocean, and far away from the world’s largest powers.

Oceania is a vast region that stretches from the North Central to the Southwestern Pacific Ocean. It is made up of thousands of diverse islands. The U.S.-controlled Pacific Islands region (Fig *) includes Hawaiʻi, as well as the U.S.-Affiliated Pacific Islands (USAPI): the Territories of Guam and American Sāmoa (AS), the Commonwealth of the Northern Mariana Islands (CNMI), the Republic of Palau (RP), the Federated States of Micronesia (FSM), and the Republic of the Marshall Islands (RMI). Larger countries in this region also in this region are the continental islands of Australia, Aotearoa (New Zealand), and New Guinea (Fig. *). Oceania has a land area of 8.5-kilometer squares and a population of 41 million people.

The physical environment spans the deepest point in the ocean (Mariana Trench National Monument) to the alpine summits of Hawaiʻi Island. The countries, island states, and territories in this region are all connected to the Pacific Ocean, which covers one-third of the Earth. The Pacific is surrounded by the Pacific Rim, also known as the Pacific Ring of Fire. Subduction zones that surround the Pacific Ocean are home to many volcanoes—about 75% of the world’s volcanoes are located here along with the strongest earthquakes—90% of the world’s with the earthquakes occur along its path. These are attributed to the amount of movement of tectonic plates in the area.

To understand the distribution of these islands in the Pacific, it is important to understand the theory of Plate tectonics. It is based on the idea that the Earth's rigid outer layer (the crust or lithosphere) consists of about a dozen large pieces called tectonic plates. These plates rest on top of the mantle, a layer below the crust that has a molten, flexible quality, and moves relative to one another. At the subduction zones, denser oceanic plates are subducting underneath the less dense continental plates. This is where the recycling of the lithosphere, beings. Oceanic plate melts under heat and pressure, turning back into molten magma, then eventually erupts into a volcano that forms islands.

Fig. * illustrates the Pacific Plate and is moving northwest at a speed of 56–102 mm (2.2–4.0 in)/year. Note the subduction zones—along the western boundary of the Pacific plate—and segments of transform and divergent plate boundaries.

There are three general types of islands in Oceania: continental islands, high islands, and low islands. Most of Oceania’s islands were created by two distinct processes, either volcanic eruptions or alternatively, core reef-building. When a volcanic island emerges from the ocean, the outer edges provide critical habitat for coral reef growth. Over time, as the island is exposed to atmospheric elements, it erodes away and gradually sinks into the ocean. The reef surrounding the volcanic island continues to grow and eventually, the volcanic center may disappear, leaving an arc-shaped reef with a lagoon center where the island core had once been.

Learn more about atoll formation  here .

Australia's physical landscape differs from New Zealand's.

In general, the islands of the Pacific have a warm, tropical climate with little seasonal variations in temperature. There are a few islands that experience season rainfall, primarily during the winter months brought on by orographic lifting, which occurs when the wind blows against high mountains and air is forced to rise, this produces orographic clouds and rain. In Hawaiʻi, “trade winds” persistently blows from the East Northeast direction, therefore the windward slopes are often cloudy with wet conditions. Trade winds coupled with topography define the rainfall patterns in Hawaiʻi, and the windward mountain slopes receive abundant rainfall annually (Fig *).

In New Zealand, the climates are defined by latitude, the Pacific Ocean, and local topography, however, it is primarily a maritime climate. The majority of Australia’s coastal areas have higher rainfall, whereas the interior is dry and receives less rain annually, due to a dominant subtropical high pressure. The northern parts of Australia’s climate are classified as tropical rainy and can experience monsoonal rains, during the Southern Hemisphere’s summer months, December to March, the opposite occurs in the winter, June to September.

Wildlife in this region is one of the most distinct in the world due to its relative isolation from other continents. The study of the spatial distribution of the world’s flora (plants) and fauna (animal life) is called biogeography. Australia, New Zealand, and the Pacific islands are home to species found nowhere else in the world (endemism). The Hawaiian Archipelago, the most isolated group of islands in the world, is home to a large number of endemic species, has the highest number of animals in danger of becoming extinct, and it is often referred to as the “endangered species capital of the world.” This is mainly due to native habitat destruction by humans, and the introduction of alien species, plants, animals, and microorganisms that occur in a particular place unnaturally, and invasive species, species that spreads rapidly and causes problems for the native species, that drove and are driving many endemic species to extinction.

Oceania is home to globally important marine and terrestrial ecosystems, as well as unique cultural diversity. Changes in the atmosphere, land, and ocean result in impacts to multiple sectors and communities, including built infrastructure, natural ecosystems, and human health. For example, climate change, such as changing rainfall patterns and sea-level rise are impacting groundwater and groundwater-fed surface environments (e.g., wetlands, lakes, and ponds) in low islands. For residents living on atolls, they depend on shallow aquifers for basic needs and for food production. Inundation of seawater contaminates freshwater supplies. Large-scale climate variability, such as El Nino-Southern Oscillation, can significantly affect rainfall, air and ocean temperature, sea surface height, storms, and trade winds in the Pacific Islands region. Significant temperature changes have already been observed in this region. In Hawaiʻi (Fig *a), over the past 100 years (1917-2016), the temperature has warmed significantly at 0.052°C/decade (0.094°F). This warming trend amounts to more than half the global rate over the past century of 0.098°C/decade (0.18°F,  NOAA/NCEI, 2017 ).

High temperatures increase evaporation, which in turn reduces water supply and increases water demand. Check out the article (link below) to learn how residents of American Samoa are adapting to these changes in climate and what they are doing to preserve their water supply.

Migration is a major theme in Oceania, beginning with the earliest settlement of the large islands of New Guinea and Australia by Aborigines approximately 60,000 years ago—who came from Southeast Asia—to prehistoric Polynesian long-distance navigators, who settled Hawaii by 800 CE, to the more recent European emigrants that populated Australia and New Zealand.

For thousands of years, traditional Polynesian navigation was used to make long arduous voyages across thousands of miles of the open Pacific Ocean. Polynesian navigators had (and have) a deep understanding of coordinate locations and the navigation guides to move between them. Dennis Kawaharada of the Polynesian Voyaging Society gives a  summary of wayfinding techniques . The successful migration across the Pacific Ocean and settlement on remote islands by these ancient navigators proved to be an extraordinary odyssey because they mastered these techniques and the knowledge was passed by oral traditions for generations, usually in the form of a mele (song).

In 2014,  Hōkūleʻa  (Star of Gladness) celebrated 40 years of voyaging in the Pacific. Launched from the sacred shores of Kualoa in Kaneohe Bay on Oahu on March 8, 1975, she helped begin a generation of renewal for Hawaii's people. In 1999, Hōkūleʻa voyaged to Rapa Nui closing the Polynesia Triangle. The Polynesia Triangle (Fig. *), which includes Hawaiʻi, Rapa Nui, and Aotearoa (New Zealand) covers ten million square miles of water. Along with the revitalization of Polynesian voyaging and navigation traditions, Hōkūleʻa introduced newfound respect and appreciation for Hawaiian culture and language in the state of Hawaii and beyond.

The Hōkūleʻa recently concluded its epic three-year sail around the globe and returned home to the Hawaiian Islands in June 2017. The mission of this voyage was to spread the message of Malama Honua, or caring for Island Earth, by promoting environmental consciousness, fostering learning environments, bringing together island communities, and growing a global movement towards a more sustainable world. The voyage has celebrated a resurgence of pride and respect for native cultures and has created an opportunity for people throughout the world to honor the shared Hawaiian heritage. The Malama Honua sail included over 150 ports, 18 nations, and 8 UNESCO Marine World Heritage sites. Check out the  map of the voyage  and the visual  history of Hōkūleʻa  and the Polynesian Voyaging Society.

Historically, Native Hawaiians had an efficient and sustainable communal land management system called the ahupuaʻa—traditional Hawaiian land division and socio-economic sections that usually ran from the mountains to the sea. Each ahupuaʻa was carefully designed to provide within its borders the natural resources a community required to meet its own needs—mountain to ocean resources.

Estimates vary on the size of the Hawaiian population at the time Europeans arrived -- it is conceivable that it was about a million people -- not that different from today. So, how did a population of that size survive without the Matson ships that we all rely on today? It is nothing short of amazing. Hawaiians regarded nature as familial and ancestral, sacred, and valuable and their intensive agricultural practices have supported the substantial population in Hawaii, estimated at 400,000 - 800,000, prior to European contact in 1778 (Gon et al., 2018). These self-sustaining units serve as a model for sustainability in Hawaiʻi today.

Gon, S. M., Tom, S. L., & Woodside, U. (2018). ʻĀina Momona, Honua Au Loli—Productive Lands, Changing World: Using the Hawaiian Footprint to Inform Biocultural Restoration and Future Sustainability in Hawai ‘i. Sustainability, 10(10), 3420.

Kabutaulaka et al. (2017). Health and Environment in the Pacific. Honolulu: Center for Pacific Islands Studies, University of Hawai'i–Mānoa.

Keener, V., D. Helweg, S. Asam, S. Balwani, M. Burkett, C. Fletcher, T. Giambelluca, Z. Grecni, M. NobregaOlivera, J. Polovina, and G. Tribble, 2018: Hawai‘i and U.S.-Affiliated Pacific Islands. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 1242–1308. doi:  10.7930/NCA4.2018.CH27 

McKenzie, M. M., Giambelluca, T. W., & Diaz, H. F. (2019). Temperature trends in Hawaiʻi: A century of change, 1917–2016. International Journal of Climatology, 39(10), 3987-4001.

Hau'Ofa, E. (1994). Our sea of islands. The Contemporary Pacific, 148-161.