results of overpopulation and the Easter Island case study

Close Window results of overpopulation and the Easter Island case study From: Humans and the Natural Environment, Our Fragile Planet. Ecosystems are disappearing due to the creation of farmland and the building of cities. Pollutants are contaminating the air, water, and land and are causing global temperatures to rise. Species are going extinct at a high rate, mostly due to habitat loss, but increasingly due to other environmental changes, like global warming. All of these changes are the result of human activities. It remains to be seen whether the planet's carrying capacity for humans has been exceeded, or whether people can learn to live sustainably. The Current Extinction Crisis Biologists agree that the greatest threat to life on Earth is the degradation and destruction of ecosystems. The land from nearly half of the planet's ice-free areas has been transformed for human uses: By 2032, more than 70% of the Earth's surface will likely to have been altered. Incredible losses have already occurred in the ecosystems of the developed nations, such as in the temperate forests of North America and Europe. Destruction is currently accelerating in developing nations, particularly in wetlands and tropical rain forests. Each transformed ecosystem is no longer the perfect habitat for its native species, and many of those species are likely to experience population reductions, or even extinction. Habitat loss is the primary threat to 85% of endangered and threatened species in the United States, and possibly even more globally. The rate at which species are going extinct worldwide is increasing. The Millennium Ecosystem Assessment by the United Nations Environment Programme (UNEP) found that the current global extinction rate is between 100 and 1,000 times higher than the average over geologic time. The extinction rate in 50 years is forecast to be more than 10 times the current rate. Biologists call species loss of this magnitude a mass extinction. Although mass extinctions have occurred in the planet's history caused by asteroid impacts, climate change, or unfathomably large volcanic eruptions none of these events has been caused by the actions of a single species. Worldwide, an estimated 30,000 species are lost per year, or an average of about three per hour. At this time, most of these losses are taking place in the biologically rich tropical regions. The World Conservation Union, or the International Union for the Conservation of Nature and Natural Resources (IUCN), projected in 2004 that about 1 million land organisms will disappear in the next half-century. In all, some 12% of birds, 20% of reptiles, at least 32% of amphibians, as many as half of the plant species, and 25% of mammals (including lions, rhinos, tigers, and most primates) could be extinct by the end of this century. Harvard University biologist Edward O. Wilson has an even more dire prediction: He estimates that one-half of all species on Earth will be extinct by 2100. As Jeffery Sachs stated at the State of the Planet 06 conference, "Every single major ecosystem on the planet is under profound stress. It should be the number-one talkedabout issue, because it is right at the core of our needs, our survival, and our future prospects." Easter Island: A Cautionary Tale Page 1 of 6

In the middle of the Pacific Ocean, 2,300 miles (3,700 km) west of Chile, lies tiny Easter Island, only 66 square miles (171 sq. km) in area. Known as Rapa Nui to its inhabitants, the volcanic island is unique because of its moai, the beautiful and eerie stone statues built by the island's inhabitants. In addition to these wonders, Rapa Nui is becoming known for a different reason: "Scientists recognize Easter Island as the best example of an environmental catastrophe caused by humans," said Jared Diamond in his 2004 book Collapse: How Societies Choose to Fail or Succeed. In this catastrophe, overpopulation and overuse of resources played critical roles. Rapa Nui was colonized by Polynesians in about A.D. 900. The Polynesians were clearly looking for a new home since they arrived in their boats with bananas, taro, sweet potatoes, sugarcane, paper mulberry, and chickens. Inadvertently, they also brought rats. The island they found was a rich and diverse subtropical forest of tall trees and woody brush. The Easter palm grew more than 65 feet (25 m) tall and 3 feet (1 m) in diameter. The tallest trees were the Toi (Alphitonia zizyphoides) and Elaeocarpus rarotongenesis, which grew up to 100 feet (30 m) and 50 feet (15 m), respectively. Native species of land birds, lizards, and turtles wandered the land and seabirds nested on its shores. The island presented a few difficulties to the colonizers. It is cooler, windier, and drier than most of the other Polynesian islands, and only one freshwater stream runs across it, although water collects in pools in other locations. Offshore, the island drops steeply off into the deep sea, and the relatively cool water does not allow coral reefs to grow. When the settlers arrived, common dolphins (Delphinus delphis) swam in the cool waters nearby, as did seals, and large fish like tuna. Once the Polynesians arrived on Rapa Nui, they did not receive any outside influence or help. Initially, the island was a paradise. The people consumed nuts and took sap from the Easter palm to make into syrup or wine; they also made its fronds into baskets, mats, and boat sails, and used its trunks to construct rafts. They carved the tall trees into canoes, which gave them access to the fish and dolphins offshore. They also used various trees and shrubs for construction, carving, rope, tapa cloth (for clothing), harpoons, outriggers, fruits, nuts, and firewood. The dead were cremated in enormous firewood funeral pyres. Archeologists have excavated garbage dumps (more appealingly called middens) to understand the evolution of cultures. (Middens hold the remains of what people ate, wore, and used: The bottom layers represent the earlier years, and the top layers the later years.) On Rapa Nui, the lower levels of middens contain many bones from common dolphins, land and sea birds, seals, and large fish. The presence of charcoal indicates that this wide assortment of meat was cooked before being eaten. The Polynesians also farmed and raised chickens in stone coops. The island was inhabited by 11 or 12 clans, each with its own territory that covered coastline, flatlands, and uplands. These clans also shared the island's resources. The statues they left behind look eerily alike: a large head set on a legless body wearing a loincloth. Some have eyes constructed of a white coral iris and a pupil of a red volcanic rock. Some have pukaos, red stone cylinders that weigh up to 12 tons (11 metric tons), placed on top of their heads. Some of the 300 platforms on which the moai rest are constructed of large stone slabs up to 13 feet (4 m) high and weighing up to 10 tons (9 metric tons) placed in a rectangle. The slabs serve as retaining walls for the hundreds of tons of rock rubble placed inside. The moai were erected near the coast with the statues facing inland in the direction of the clan that erected them. The cost of creating and mounting the moai was tremendous. Special craftsmen carved the statues in the quarry. When carving was complete, the statues were placed in wooden sleds that were moved across the land on heavy logs spaced along the ground and connected as a sort of ladder. Workers gathered to pull simultaneously on thick ropes that were attached to the sled. Experiments with modern Easter Islanders have shown that 50 to 70 people working five hours a day could transport a 12-ton (11 metric ton) statue nine miles (14 Page 2 of 6

km) in one week. The largest statues might have required the work of 500 adults, which would have been possible only when the island population was at its highest. Once a statue reached the platform, it was levered up using stones and logs until it stood vertically. Diamond estimates that the clan probably needed about 20% more food than usual to support the building and transport of the moai. The bulk of this activity began in about 1300 and took place over the 300 years that coincided with the years of greatest productivity for the upland plantations. Although farming the upland areas was more difficult than farming the lowlands, farms moved uphill because there was more rain. During the best years from 1400 to 1600, the population may have risen as high as 30,000. The Rapa Nuians harvested tremendous amounts of wood from the island's forests to transport the moai and for other uses. The people also cleared trees to grow food. While human activities took a toll on the forest, so did the rat population: Every nut from an Easter palm that has now been found was previously chewed by a rat. Since damaged nuts could not germinate, mature trees could not be replaced. As a result, the island's trees began to disappear in the sixteenth century. Easter palms and other Rapa Nui island trees are now extinct. Without trees, there was no material left to make boats, cloth, rope, and tools, or for warmth and cooking food. With the ecosystem so altered, native birds and mammals died out or were hunted to extinction. Eggs and young animals were probably eaten by rats. The higher layers of the middens have few or no bones of fish, dolphins, and seabirds since the Rapa Nuians did not have logs for making boats to go fishing. Wild fruits and nuts were no longer available. As people became hungrier, they decimated the larger shellfish and began to eat smaller species. As the lands were deforested, topsoil eroded away, and nutrients became scarce. The upland plantations ceased to be productive, and between 1600 and 1680 they were abandoned. "The overall picture for Easter is the most extreme example of forest destruction in the Pacific, and among the most extreme in the world: the whole forest gone, and all of its tree species extinct. Immediate consequences for the islanders were losses of raw materials, losses of wild-caught foods, and decreased crop yields," writes Diamond in Collapse. With so many food resources gone, the seventeenth and eighteenth centuries were a time of starvation for the islanders. The number of home sites on the island decreased by about 70%. To memorialize this time, the island has many small carved statues of starving people "with hollow checks and protruding ribs," says Diamond. The upper layers of the middens show that the Rapa Nui in the later years ate chicken, rats, and high-carbohydrate crops. Deforestation caused rainwater to run off the land quickly and water for drinking and domestic uses became scarce. Although there is some doubt about this, many anthropologists believe that the Easter Islanders then resorted to cannibalism, a hypothesis that is supported by oral tradition. Certainly, evidence of human bones that were cracked to extract the marrow has been found on the island. When food was abundant, the building of the moai appears to have been peaceful. Over time, the statues increased in size, a sign that there was competition between chiefs and possibly an attempt to appease the gods to provide more food. As deforestation progressed, the islanders were unable to make lumber or ropes for transporting the statues. The last moai were erected around 1620, and many were abandoned in the quarry and along transport roads. As they failed to deliver food and water year after year, the authority of clan chiefs and religious leaders grew precarious, and their relationships with the gods were questioned. The leaders were overthrown in a military coup in 1680. Civil war erupted. Angry residents toppled the moai so that they would break when they hit the ground. Some of the moai have been reconstructed for the benefit of the tourists who visit the island. The first record of contact between Rapa Nuians and Europeans took place on Easter Page 3 of 6

Sunday (hence the name Easter Island) in 1722. The captain described 2,000 to 3,000 islanders who possessed only small, leaky canoes for transport. His log does not mention the presence of trees over 10 feet (3 m). In 1774, Captain Cook stayed at the island for four days. At that time, some of the moai were still standing. He described the residents as "small, lean, timid, and miserable." In the following centuries, many Rapa Nuians were killed by European diseases or were removed from the island to become slaves. By 1877, the island's population had fallen to only 110. Diamond uses what happened on Easter Island as an allegory, "a worst-case scenario, for what may lie ahead of us in our own future." The nations of the world are now as integrated in their sharing of resources as were the clans on Easter Island. Rapa Nuians could not rely on help from outside, nor can humankind today. As then, there is nowhere for excess population to go. Diamond recognizes that this is an imperfect metaphor: Easter Islander population numbers were much lower and their tools were relatively primitive, compared to people in the world today but how much does having more people in a larger world with more sophisticated tools really help? Results of Overpopulation and Overconsumption The carrying capacity of a species in a location is exceeded if resources are being depleted faster than they are being replenished. Since 60% of resources are now being used at a faster rate than they are being replaced in nature, the carrying capacity of the planet is being exceeded by the current human population. This means that for the current level of consumption, the planet is overpopulated. Some of the effects of overpopulation and over-consumption that are currently being seen are difficulty providing clean water and sewage treatment for large numbers of people. overuse of natural resources including forests, fossil fuels, and minerals. loss of arable land due to urbanization and soil degradation. loss of ecosystems and consequent species extinctions due to land-use changes. increased pollution of the air, water, and land. atmospheric changes leading to climate change. Many people are also suffering in regions that are overpopulated. They are experiencing starvation and malnutrition. high incidence of poverty. high infant and child mortality. low life expectancy. increased infectious diseases due to overcrowding, ecosystem disturbance, and overburdened health care systems. high unemployment and resultant social problems. high crime. fighting and war due to competition for resources. overused human infrastructure: roadways, health care systems, etc. Asked the approximate value of Earth's carrying capacity for people, Paul Ehrlich, in an interview with the online magazine Grist in August, 2004, stated, "Carrying capacity depends on the behavior of the organisms (people, in our case) involved the carrying capacity of Earth for vegetarian saints is much higher than for the present mix of people. For that present mix it is easy to show we're in overshoot way above the carrying capacity." How Population Will Grow Nearly all of the growth in population is in developing and poor nations, and much of that is Page 4 of 6

in the slums that sprawl around major cities. Slums grow because farmers lose their ability to produce enough food to feed their families due to changes in agricultural practices, land degradation, adverse weather, and increased family size. They then move into cities to look for work, which often is not available. Even in rapidly developing nations, these poor people are excluded from rising standards of living. Today, 600 million slum-dwellers do not have adequate shelter and 400 million do not have latrines. Slums may be located next to major roads, factories, or dumpsites so that the inhabitants are exposed to high levels of air and water pollution. Most of these people lack garbage collection and proper sanitation. Poor drainage allows wastewater to collect, creating an ideal environment for disease-carrying insects to breed. Crowded conditions also allow diseases to spread more rapidly. By 2030, nearly 5 billion people, 60% of the world's population, will live in cities and towns, mostly in slums. As the environment deteriorates, many places will become unlivable. If ecosystems collapse, economies may collapse with them, leaving people without life's basic necessities. If global warming causes high temperatures to melt ice sheets, then sea levels will rise and inundate billions of people's homes with water when storms strike. Situations like these will create what are called environmental refugees, people who are displaced from their homes by environmental deterioration. The group includes climate refugees, those who are displaced by increases in extreme weather events, sea-level rise, or any other effect of climate change. There may already be millions of environmental refugees. Immigrants to the United States and Europe are sometimes driven by deteriorating soil and water conditions in their native lands. The United States may already have its own environmental refugees those Americans who were driven from New Orleans and other Gulf Coast locations by the 2005 hurricanes Katrina and Rita. The Red Cross says that the number of people in the southwestern Pacific who have been affected by weather-related disasters has increased 65 times in the past 30 years. Many of these people have already become, or will soon become, climate refugees. According to a 2005 United Nations report, by 2010 there may be as many as 50 million environmental refugees worldwide, driven from their homes by rising sea level, desertification, and catastrophic weather events. The U.N. is urging the international community to recognize "environmental refugees" as a refugee category, which will make them eligible for the same assistance given to traditional categories of refugees. People in the developed nations may think that the problems caused by climate change will largely leave them untouched. But, like New Orleans, low-lying coastal cities will need to be protected from rising seas or they will be lost. Warmer temperatures will cause extreme weather events to increase in frequency. The combination of higher seas and more-extreme weather has the potential to create enormous numbers of environmental refugees within the developed nations. There is also the risk that, if people in the developed nations are seen as being better off than people elsewhere, increasing numbers of immigrants, legal or illegal, will be clamoring to move in. Can Sustainable Development Be Realized? One very important step toward achieving sustainable development is to continue to reduce population growth rates. World fertility rates have decreased from six children in 1960 to three today due to economic development and access to family planning. When women are educated and allowed to make reproductive choices, their productivity, economic situation, environmental management, and reproductive health improves: Child and maternal mortality decreases and the daughters they do have are more likely to be educated; demand for family planning increases and birthrates go down, as do abortion rates, including those for unsafe abortions; the spread of sexually transmitted diseases slows down, along with the spread of HIV/AIDS. If sustainable development is to be achieved, science will play an important role. Scientists need to better understand how the world's ecosystems and climate work so that they can Page 5 of 6

recognize how human activities are changing them. Scientists will also help to develop technologies that can be used wisely to solve problems. Used correctly, genomics can lead to better health management, improved aquaculture for supplying fish and seafood, and better agronomy to increase the types of environments in which food can be grown. Steps can be taken that lead to better water management practices. Engineering advances can introduce better ways to use resources, such as the development of cleanly burning fossil fuels and methods to capture and sequester carbon. Alternative energy sources, such as solar power, can also be developed. Scientists will need to help politicians and citizens understand the problems and get onboard with the solutions. Citizens will need to change their behavior to reduce the impact everyone has on the planet, and politicians will need to lead the way, by both understanding the problems and convincing citizens that the changes they advocate are the right ones. As Jeffrey Sachs said at the State of the Planet 06 conference, "The fact of the matter is we need science and engineering, which is the translation of science into practical objectives. We need science and engineering right in the forefront if we are going to achieve sustainable development on the planet. If we don't achieve sustainable development on the planet, what that portends for us is a world of much greater risk and upheaval than we have right now." Wrap-up The Rapa Nuians made many mistakes, primarily by not recognizing that their resources were limited. They also did not understand the effect their actions would have on the rest of their island: That if a slope was deforested, for example, it would no longer be useful for farming. This same story plays out in many ways in the modern world. The question is whether people can change course now and stop this sort of destruction from happening on a planet-wide scale. As Jeffery Sachs said at State of the Planet 06 conference, "I'm not making a forecast but I am making a warning. If we don't change our trajectory and if we don't harness science and technology to do it in a wise way we're going to be building up a lot of pressure on each other and on our planet in ways that will be very dangerous in the years to come." Citation Information MLA CMS APA Desonie, Dana. "results of overpopulation and the Easter Island case study." Science Online. Facts On File, Inc. Web. 13 July 2011. <http://www.fofweb.com/activelink2.asp? ItemID=WE40&SID=5&iPin=OFPHNE0015&SingleRecord=True>. How to Cite Record URL: http://www.fofweb.com/activelink2.asp?itemid=we40&sid=5&ipin=ofphne0015&singlerecord=true Return to Top Page 6 of 6