Vanishing Species

What is Threatening Species? Human Population Growth

Settlers in increasing numbers are entering tropical forests, grasslands and other wild areas teeming with wildlife, and clearing them for grazing livestock and planting crops. Loggers in the Brazilian and Central African rainforest wildernesses are building roads to transport entire forests of trees, some thousands of years old, to be sold in markets in North America, Europe and Asia. The roads open up the forests to settlers and hunters, endangering countless species of animals. Commercial exploitation of forests has increased rapidly since the 1980s, with logs turned into pulp for paper, expensive lawn furniture, paneling, shipping cartons, and even concrete molds that are used once by builders and thrown away. Rivers are becoming increasingly polluted from human waste that goes untreated in many parts of the world, and billions of people scratch out a living by subsistence farming, cutting trees for fuel and grazing livestock.

These poverty-stricken people have caused the limits of the Sahara and Sahel in Africa to expand by depleting wildlife and trees, and have razed forests in India, China, Indonesia, Thailand, Ecuador, Central America, Mexico and West Africa. Still, many go hungry because they have far outstripped what the land could supply sustainably. For the wealthier nations, an appetite for material goods and demand for a high standard of living have encouraged a market for precious resources, such as tropical lumber and wildlife products, that has expanded in recent years with the World Trade Organization (WTO) globalized economy. In order to repay loans granted to them by international funds, many poor nations strip their forests and grow exportable crops on the land. In the United States, urban sprawl and overexploitation of forests and other resources have threatened a host of animals and plants. Water is diverted for these new towns, endangering native fish and forests. In Arizona, the Sonoran Desert, a botanical world treasure, is now being destroyed by the expanding cities of Phoenix and Tucson.

The needs of the growing numbers of people worldwide have spawned many ill-conceived and environmentally destructive projects. Indonesia and Brazil opened up the most biologically rich forests on Earth to farming by people living in overpopulated cities. The soil is poor in tropical forests, and they must keep clearing land to find new areas for crops, gradually destroying vast areas once teeming with wildlife. China has moved people into western grasslands, where they have eliminated wildlife and caused massive erosion and desertification with agriculture and overgrazing of livestock. Dust storms from this region have been circling the globe in recent years. China has also commissioned the world's largest dam, Three Gorges--on the Yangtze River--in an attempt to control floods and generate electricity. In the process, a very rare freshwater dolphin, a sturgeon, and hundreds of rare plants will become extinct, and the dam's lake will fill with untreated sewage. The problem of overpopulation has not been well understood or coped with in the majority of countries where populations are now outstripping food supply.

In most parts of the world, however, people have deforested the habitats and killed prey species of wide-ranging wildlife that have nowhere else to go. Asian Elephants (Elaphus maximus) and Tigers (Panthera tigris), for example, have been deprived of habitat and food and crowded into areas too small for their requirements. When they rampaged into people's gardens or killed livestock, they were killed and their body parts sold for high prices. Both species are now endangered, their populations fragmented and in steep decline. This is a pattern that has been seen with large animals, especially predators, throughout the world. Animals or plants with low populations as a result of restricted habitat size or specialized requirements for survival have been pushed to the brink of extinction as humans moved into their habitats.

Only a few countries have national policies to encourage stable populations. In some countries with populations that far exceed the ability of the land to adequately sustain them, wars have broken out, providing an apocalyptic vision of a violent future for the Earth should present trends continue. A scientific study, Environmental Change and Violent Conflict (Homer-Dixon et al. 1993), predicted that as human populations increase and resources decrease, wars will occur with ever greater frequency. Population Action International, a Washington, DC-based organization, calculated in 1997 that although human population growth has slowed somewhat, water resources remain under serious threat. This organization's report warns that by 2050, people in the Middle East and parts of Africa, where populations continue to grow at high rates, will be engaged in bitter, violent conflicts over water. The story of the Rwandan war, described later in this chapter, reflects this cause and effect. Overpopulation causes human suffering, permanent damage to the land from overuse, and the destruction of the very species that might prove life-saving. A few countries, such as Singapore, launched education programs decades ago, urging people to have smaller families for a better quality of life. The rate of population increase in this tiny country is now less than 1 percent, and literacy is 91 percent.

Medical advances preventing disease and early mortality in people around the world, combined with growth in agricultural output, have played a major role in the nearly four-fold rise in human population since 1900. The World Health Organization (WHO) has scoured the planet eradicating disease but is not required to educate people about birth control methods. This has decreased natural mortality and fueled population booms. The majority of international aid projects lack overview, coordination with one another and long-term planning. Supplying high-yield grain and financing irrigation projects to poor nations, without providing birth control education, results in a doubling of populations within a generation, which negates any rise in the standard of living and education levels. By encouraging livestock and agriculture in dryland areas, with little knowledge about the natural environment or its capacity to support large numbers of people, wildlife and plants are displaced or killed, and in years of drought, crop failures result, causing starvation. The human suffering brings international aid with emergency food, and instead of relocating people to other areas, these programs encourage replanting and a repetition of the misfortune.

Ethiopia and Somalia are examples of such policy failures. These countries were covered in a mosaic of grasslands and forests teeming with endemic wildlife early in the 20th century. An influx of large numbers of people and livestock, encouraged by aid programs, denuded this region to arid desert. The vast numbers of wildlife have largely disappeared or become endangered as the extensive grasslands, rivers, lakes and highland forests disappeared because of overgrazing, farming in areas too dry to produce crops and deforestation for firewood (see Grasslands, Shrublands and Deserts chapter). With low human and livestock population densities, these areas could have remained ecological treasures.

The Population Institute of Washington, DC, warns that although some countries have shown declining rates of population increase, especially those in Western Europe and North America, this will not result in an overall decline in world population because of greater human longevity, continued high birth rates in at least 74 countries and a high survival rate (Holmes 1997).

The top 10 countries in terms of overall numbers of people have 59 percent of the world's population. More than 30 percent of all births in 1997 took place in India, a country expected to overtake China as the world's most populous nation by 2050 (Holmes 1997). A 1997 World Bank report, "The World Food Situation: Recent Developments, Emerging Issues and Long-Term Prospects," concluded that food stocks are not keeping up with need (Crossette 1997b). Demand for meat is increasing, placing further stresses on natural systems since livestock consume enormous amounts of grasses and grain, cause damage to vegetation and often pollute water systems; grain production is reaching the limit of potential yields, especially in Asia (Crossette 1997b).

The most densely populated country in the world, Bangladesh, with 127.5 million people, has about half the population of the United States in an area the size of Wisconsin. It has a density of almost 3,000 people per square mile, and a population growth rate of 2 percent a year. Ninety percent of the people in Bangladesh's countryside are illiterate and malnourished in spite of decades of international aid projects. Bangladesh is now totally dependent on foreign aid for minimum nutrition, and the land is being worked to maximize yields, using large quantities of fertilizer, irrigation and pesticides. The once vast mangrove forests that serve as fish and shellfish nurseries, and habitat for Tigers and other endangered species, are being destroyed piecemeal, cut for firewood (Worker 1996).

Funds to encourage birth control around the world have been deleted from US budgets by those opposed to abortion, thus thwarting all types of programs of education, birth control methods and related issues. Most organizations working to lower birth rates around the world use almost no funds for abortion, yet they find their funds cut for all family planning programs. This obstructionism has been a major setback to those working to stabilize the world's populations. The United Nations Population Fund has continued to carry out family planning programs, but with inadequate funds.