Magazine article New Internationalist

Planet Pacific: The South Pacific Was the Last Habitable Region on Earth to Be Settled by Human Beings. It Is Now Becoming the First to Be Made Uninhabitable

Magazine article New Internationalist

Planet Pacific: The South Pacific Was the Last Habitable Region on Earth to Be Settled by Human Beings. It Is Now Becoming the First to Be Made Uninhabitable

Article excerpt

Planet Pacific

The South Pacific was the last habitable region on earth to be settled by human beings. It is now becoming the first be made uninhabitable.

GONDWANALAND

About 160 million years ago Antarctica, Australia, South America, India and part of South - East Asia formed the single supercontinent Gondwanaland. It gradually broke into 'tectonic plates' which are still moving today. Where they pull apart, molten magma sometimes breaks the surface to form ridges. Where they come together, one plate plunges beneath the other, throwing up mountainous ridges to one side and deep oceanic trenches to the other. Most of the islands of the South Pacific are formed by one of these two forces. The Pacific remains the most volatile geological region on earth.

FREEZE AND FLOOD

During the past two million years there have been at least 20 occasions when the earth's climate was colder than it is now. At such times, because water cooled and contracted, sealevels fell. The islands of the South Pacific were then larger and fewer. At the height of the last ice age, 18,000 years ago, the sealevel in Fiji was between 120 and 150 metres below the current level. By the end of the Ice Age most of the older island ecosystems became stabilized with grassland, woodland and tropical rainforest. This made them suitable for human settlement.

MIRACULOUS MIGRATIONS

People probably first moved from Indonesia to New Guinea and Australia between 40,000 and 50,000 years ago, when sealevels were low. With the end of the Ice Age sealevels rose and longer - distance migrations in dug - out canoes began. By the time of the 'Little Climate Optimum' between 1200 and 650 BC temperatures were higher than they are now, with persistent trade winds, clear skies and few storms. These were favourable conditions for oceanic migrations: among the greatest feats of navigation ever accomplished. People finally reached the Marquesas Islands to the east about 2,000 years ago. From there they went on to form the 'Polynesian Triangle', with Hawai'i to the north and Aotearoa/New Zealand to the south, by about 750 AD - though evidence of earlier settlement is now being examined.

HUMAN IMPACT

Migration brought great changes to island ecosystems. New crops and animals were introduced and forests were cleared for cultivation. Combined with the effect of tropical storms, these increased soil erosion. The sediment from erosion, in turn, smothered coral reefs. Reefs protect many islands from the ocean and are rich in fish. Most island ecosystems were badly degraded within 1,000 years of human settlement. Pollen records show that forests on Rapa Nui (Easter Island) were completely destroyed. On Aneityum, southern Vanuatu, early settlement and forest clearance on the uplands led to soil erosion and forced a shift of population to the lowlands - similar shifts had to be made on other islands, too. …

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