“5.6 Billion Served!” It may sound like the claim you see at a well-known fast-food restaurant. But it’s not hamburgers. It’s how many people our planet must serve, or support, with food, clean water and air, raw materials for clothes, medicine, and the other necessities–and luxuries–of life. Every year, the number of passengers on spaceship Earth increases by 100 million. By 2020, scientists estimate the Earth will need to support nearly 8 billion people.
In the late 1960s and early 1970s, books like The Population Bomb and The Limits to Growth predicted major disasters because of unchecked population growth. These books said the Earth could not feed the expected population of the late 1970s. These predictions did not consider advancements in agricultural science.
The Green Revolution
The reason for these agricultural advancements was a revolution. A green revolution. By applying new agricultural technology and techniques, scientists were able to dramatically increase crop yields in countries around the globe. It had been predicted, for instance, that by 1979 India would experience horrible famines. Instead, it was producing enough food to feed its own people and to export to its neighbors. In most of the recent cases of famine in the world, political unrest or poor economic policies, not the environment, have been key factors.
But today, the world’s population continues to grow at a rate of nearly 100 million people a year. And it appears that many productivity gains of the Green Revolution are leveling off. Once again, some scientists are voicing concerns about the Earth’s ability to support an ever-growing population. These concerns center around three recent developments: the loss of biodiversity, growing pressure on farmers and the land to produce more food, and the growth of the megacities.
Recently, scientists around the world have become alarmed at the growing loss of biodiversity. Biodiversity refers to the variety of plants and animals in the Earth’s environment, their genetic makeup, and the role they play in the ecosystem. Loss of biodiversity can mean a reduction in the number of species of plants or animals. It can also refer to a loss of genetic diversity within a species.
Some estimates say that the world is losing about one species a day. The loss of habitat, which occurs with the clear-cutting of tropical rain forests, is a key factor in these extinctions. Equally troubling is the growing evidence that the surviving species are becoming less genetically diverse.
This loss of genetic diversity is especially worrisome when scientists look at the primary food crops of the world. An important part of the Green Revolution included widespread use of specially bred strains of major crops like rice and wheat. The new “green revolution” strains were bred to yield bigger crops at harvest.
They succeeded spectacularly. As a result, farmers stopped planting the more traditional varieties of food crops. The older varieties, more genetically diverse, had lower yields. In some cases, these older varieties have now been lost. What’s more, the new varieties often share the same genetic material. This means a blight or mold could devastate many or all of the genetically related new strains. The entire food supply of a nation could be threatened by a single plant disease. Loss of diversity is apparently making the world’s food supply less stable, even as the population grows.
The Global Farm Crisis
In developing countries, the combination of growing population and demand for more farmland to feed the people means double trouble–for the land and for the people. In rural areas, demand for firewood–a key fuel–leads to the stripping of hillsides and forests. When this occurs, farmers clear and plow poorer or marginal land for their crops. The eventual “harvest”? Erosion, flash floods, and muddied rivers.
In the race to feed more people, farming techniques such as irrigation and products like pesticides and artificial fertilizers are misused. In some places, wasteful irrigation has lowered water tables, threatening local water supplies. Overirrigation also causes the buildup of salts in the soil that make it unusable or even poisonous. This situation has happened in the Aral Sea region of Central Asia.
Since 1970, worldwide use of chemical fertilizers such as nitrogen and phosphate has increased dramatically. Nitrogen use, for example, has doubled. By the late 1980s, more than 70 million tons of the chemical were being applied to farm fields. Heavy use of chemical fertilizers discourages farmers from rotating crops or letting the land rest for a season. The result? Increased erosion and loss of valuable topsoil.
The expanded use of pesticides is mirrored by the growing number of pesticide-resistant insects, as well as a large increase in plant diseases. Combine the increase in pests and disease with the reduced genetic diversity in the key food crops and you have a potential crisis in the making.
Life in the Megacity
The most visible images of the impact of population growth come from megacities such as Mexico City, Cairo, Tokyo, and Rio de Janeiro. In only a few decades, millions of people have left the countryside for the cities. More than 70 percent of Brazil’s population now live in cities, compared to just 34 percent in 1950. Around the globe, urban populations have doubled and tripled in a few decades.
Some leave the countryside because there is not enough land to divide up among the children of large families. Others are forced out by deforestation or by loss of farmland to erosion. The highly automated agriculture needed to increase yields has also eliminated jobs.
The tidal wave of migration to the megacities has created major environmental problems. Poor people living across the street from industrial plants are at risk from continuous exposure to plant exhausts, as well as to accidents like the tragic gas leak at Bhopal, India, that killed thousands.
Overloaded or nonexistent water and sewer systems make epidemic diseases like cholera a constant threat. The exhaust from buses, cars, homes, and factories can make breathing the air of a city like Mexico City equivalent to smoking two packs of cigarettes a day!
The global rate of population increase has begun to slow, but not enough to help the environment in the next few decades. Around the world, but especially in Asia, Latin America, and Africa, the population explosion seems likely to test whether the environment can truly claim “8 billion served.”