The
size of the human population effects virtually every environmental
condition facing our planet. As our population grows, demands for
resources increase, leading to pollution and waste. More energy is
used, escalating the problems of global warming, acid rain, oil
spills and nuclear waste. More land is required for agriculture,
contributing to deforestation and soil erosion. More homes, factories
and roads must be built, occupying habitat lost by other species that
share the planet, often leading to their extinction. Simply put, the
more people inhabiting our finite planet, the greater the stress on
its resources.
Why is Population Growth an Environmental and STS Issue. It took from the beginning of time to about the year 1810 for the human population to reach 1 billion people. Just more than 100 years passed before the next billion were added, and the population doubled again to 4 billion people by 1974. By 1987, Earth was home to 5 billion human beings, and this number is growing. If the global population continues to increase at the current rate of 1.8 percent annually, it will double again in just 39 years.
A society is not sustainable when it consumes renewable resources faster than they can be replenished. In other words, an overpopulated society clears forests and uses water supplies faster than they are renewed, or pollutes faster than the environment can adapt to sustain life. By these measures, the U.S. and most other nations of the world are overpopulated.
Contrary to some people's impression, the population explosion has not stopped. In 1990 another 95 million people were added to the Earth, more than in any previous year. At this rate, the world's population would easily surpass 10 billion and could exceed 14 billion people late in the next century. No realizable amount of improvement in agriculture, pollution control, energy efficiency or other areas would be able to keep up with this pace of growth. Today's 5.2 billion humans is already more than our planet can handle.
The major consumers of the Earth's resources are the developed countries, such as the United States. While these countries contain less than 20 percent of the world's people, they consume 80 percent of its resources. Although the United States is home to just five percent of the human population, we use one quarter of the total energy. The current population of the United States is about 250 million people. At the current rate of growth we are expected to add 60 million more people in the next 50 years -- 110 times as many people as now live in Boston.
Vast areas of land in the United States have been cleared to support our population. Over 3 billion tons of topsoil are lost annually as a result of intensive farming and over-grazing. Large stretches of forest have been cut to provide wood and paper, leaving only five percent of our ancient (un-cut) forests standing. In water poor areas, high rates of growth are leading to water diversion and depleted groundwater reserves. As urban areas expand, air and water pollution are amplified.
As Susan Weber, Executive Director, Zero Population Growth said, "overpopulation does not happen only in the Third World. Each year, the U.S. adds the equivalent of another Los Angeles to its population. In just 35 years, the industrialized nations together will add another U.S. for the Earth to support. The future depends on our putting the brakes on now."
STS Actions.
• Ask students to identify which graph describes the growth pattern of the human population over the past 2000 years. Then ask them to identify the impact of the human population growth pattern on:
1. Earth's atmosphere2. Availability of mineral resources
3. Water resources
4. Trees
5. Temperature of Earth
Use the results of this exercise to identify student misconceptions.
• Get students involved in writing elected officials to support legislation to fund family planning, develop better contraceptives, and promote equality for women, and break the cycle of poverty.
• Have students do research on the size of families in the United States and other "developed countries," and compare with family sizes in "underdeveloped countries." Create a values dilemma sheet based on this idea: We should encourage small families by example and by educating others about the need to make environmentally responsible reproductive choices.
• Have students find out what efforts are being made in their own community to limit the impact of growth on the environment.
• Have students make graphs showing how the population has changed in the last twenty years in their school, their community, and state.