Routledge

Chapter 6 - STS Themes and How to Teach Them

You will find information on each of the following STS themes, with suggestions for designing activities to help students understand these STS issues.

Population Growth
Energy
Effects of Technological Development
Hazardous Substances
Water Resources
Utilization of Natural Resources
Environment

Population Growth

The size of the human population affects 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. We started the 21st Century with 6 billion people.

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 adjust 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 21st 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. Some would say today's 6 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 300 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 is 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.


STS Actions

  • Visit the Population Connection Website (formerly Zero Population Growth), and find one resource on population education that you could share with your peers. (http://www.populationconnection.org/)
  • Show students the human population growth graph, which describes the growth pattern of the human population over the past 2000 years http://www.starch.dk/isi/energy/population.htm). Then ask them to identify the impact of the human population growth pattern on:
    • Earth's atmosphere
    • Availability of mineral resources
    • Water resources
    • Trees
    • 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.

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This section on population growth modified from Ron Anastasia and Susan Weber. "Population Growth Fact Sheet," EarthNet. (A Forum on the Connect Business Telecommunications System).

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Energy

Recycling Issue

Recycling saves energy, natural resources and landfill space. In 1990, Americans threw away over 1 million tons of aluminum cans and foil, more than 11 million tons of glass bottles and jars, over 4 and a half million tons of office paper, and nearly 10 million tons of newspaper. Almost all of this material could be recycled, cutting down on the environmental damage caused by mining, logging, and manufacturing raw materials, while decreasing the amount of garbage being dumped. The average American generates 3.5 pounds of garbage every day for a national total of over 150 million tons per year. Over 70 percent of this waste could be recycled using existing technologies.

Energy Usage

Global warming, acid rain, and oil spills are problems directly related to our extravagant use of energy. Three percent of our nation's energy is used to produce packaging materials, such as bottles and cans. By recycling aluminum it is possible to save 95 percent of the energy that it would take to manufacture new products from raw materials. In other words, recycling an aluminum can saves as much energy as if the can were half full of gasoline. Americans throw away about 35 billion aluminum cans every year -- enough to rebuild our entire commercial air fleet four times over. If all these cans were recycled, we would save an amount of energy equal to 150 Exxon Valdez oil spills every year. In 1988, Americans set an all time high by recycling 42.5 billion cans -- 54.6 percent of the total. This alone saved enough energy to supply power for the city of Boston for one full year.

For every ton of paper that is manufactured from recycled pulp, 17 trees are saved and 3 cubic yards of landfill space avoid fill. With paper making up over 40 percent of our municipal waste stream, recycling could extend the lives of our existing dumps considerably. For recycling to work, however, it is important that there is a market for the new product. The U.S. uses about 40 percent of the world's newsprint supply; yet only 14 percent of this paper is made from recycled fiber. Recycled paper uses 64 percent less energy to manufacture than virgin paper and produces only one-quarter the air pollution.

At present, more newspapers are recycled than recycled newsprint bought, causing a glut in the market for recycled newsprint. Barriers to increased recycling include federal subsidies to the timber industry that make the price of virgin paper artificially low. A tax credit for those manufacturers who use recycled materials could offset this perverse incentive for using virgin materials. A worldwide paper shortage is creating opportunities for community economic development through small-scale paper manufacturing plants located near the source of supply for waste paper. For every million Americans who recycle, some 1,500 manufacturing jobs are created.

STS Actions

  • Ask students to:

    1. Make a list of the advantages of recycling paper, aluminum, steel, and plastics.
    2. How recycling saves energy.
    3. What would happen if nothing was recycled?

    Use the results to identify misconceptions, and as a starters for a recycling module.
  • Tell the students that the U.S. produces about a third of the world's newsprint supply (about 13 million tons per year---yet only 14% is made from recycled fiber. According to some estimates for every ton of recycled newsprint that is used instead of virgin paper:
  • 17 trees are saved
  • 3 cubic yards of paper avoid being land filled
  • About 25 percent less energy is used
  • 74 percent less air pollution is produced
  • 58 percent less water is used.

Have the student do some "if-then" thinking. What would happen to the forest population of trees if the amount of recycled paper produced doubled from its present value? How would this effect landfill space? What impact would it have on energy usage?

Have students investigate the environmental impact of the production of their local newspaper. They should call the newspaper, and ask the following questions:

  1. How many tons of newsprint does your paper use per year? (A) ____Tons per year.
  2. What percentage of the paper is recycled fiber? (B) _____Percent recycled fiber.
    Now they can make the following calculations to determine how many trees-worth of newsprint are used, effect on landfills, and energy usage.
    (1). To find out how many tons of recycled newsprint your paper company uses, multiply (A) by (B) and divide by 100.
    (A) ____ X (B) ____ /100 = (C) ____ tons of recycled newsprint.
    (2). To calculate how many tons of newsprint are made from virgin paper, subtract (C) from (A).
    (A) _____ - (C) ____ = (D) ____ tons of virgin newsprint.
    (3). To find out how many trees-worth of newsprint the newspaper company uses in one year, multiply (D) by 17 trees.
    (D) ____ X 17 = (E) ____trees.
    (4) To figure out how much waste paper could avoid landfill if the newspaper used all recycled fiber, multiply (D) by 3 cubic yards.
    (D) ___ X 3 = (F) _____

Hazardous Substances

Pesticides Issue

Pesticides, which include insecticides, herbicides and fungicides, are a group of poisons used for killing or repelling unwanted organisms. Each year, more than 4 billion pounds of pesticides are used worldwide. Although law requires that all new pesticides undergo a series of testing before being marketed, a 1984 study by the National Academy of Sciences found that 90 percent of all pesticides have never been tested for long-term health effects. Less than one percent of the U.S. food supply is tested for pesticides.

According to the EPA, pesticides are substances used to prevent, destroy, repel or mitigate any pest ranging from insects, animals and weeds to microorganisms such as fungi, molds, bacteria and viruses. EPA licenses or registers pesticides for use in strict accordance with label directions, based on review of scientific studies on the pesticide to determine that it will not pose unreasonable risks to human health or the environment. EPA is reviewing older pesticides to ensure that they meet current safety standards and is taking action to reduce risks where needed. For pesticides used on food, EPA sets limits on how much of a pesticide residue may remain in or on foods. EPA also sets standards to protect workers who may be exposed to pesticides on the job. EPA works to promote a safer means of pest control through research, public education, and public-private partnerships.

Many pesticides can be indiscriminate in what they kill and often harm non-targeted animals that may be beneficial to crops. In areas of heavy pesticide use, poisoning of birds, mammals and fish are common. Some of the more persistent pesticides may remain dangerous for up to 20 years, slowly leaching into underground water supplies. In the United States, pesticides have been found in groundwater supplies in 26 states. Nearly half of all Americans rely on groundwater for home use.

Every year up to two million people suffer from pesticide poisoning worldwide, resulting in about 40,000 deaths. In the United States 50,000 cases of pesticide poisoning are recorded annually. Pesticide exposure can cause cancer, birth defects and damage to a number of body organs. Children often receive greater pesticide exposure because of their greater consumption of food and air, pound per pound, than adults. One study found that in households where pesticides are used, children are much more likely to suffer from leukemia.

Over the years, many insect species have become resistant to insecticides, necessitating higher doses and increased applications of more dangerous pesticides. Over the last 40 years, pesticide use has increased 10-fold, yet crop loss has almost doubled from 7 to 13 percent.

U.S. law currently allows any pesticide to be exported as long as the importing country is notified of its regulatory status. As a result, many pesticides that are banned or restricted in the United States because of their danger to health and the environment are exported to developing countries. In many cases pesticides are applied to farm workers who are unable to read instructions or warnings on product labels (which are frequently written in English). These laborers are often inadequately protected and are exposed to heavy doses of dangerous pesticides. Ironically, 70 percent of the pesticides exported to developing countries are used in the production of food imported by the United States. Recently six percent of all agricultural imports to the U.S. carried unacceptably high levels of pesticides.

STS Actions

  • Have students make lists of the advantages and disadvantages of using pesticides. You might want to tell the students that a pesticide is a general word for poisons that control or kill insects, fungi, weeds, and rodents. Use the lists as way to identify student misconceptions.
  • Have the students investigate pheromones, which are natural sex attractants, as a safe, biological alternative to chemical pesticides.
  • Have students find out what effect the following actions have on chemical pesticides:
    • Wash fruits and produce.
    • Buy domestically grown produce in season.
    • Buy organically grown produce.
    • Grow your own food.
    • Tend the lawn without chemicals.
  • Have students find out about organic gardening.
    For further information on pesticides consult:
  • The EPA Office of Pesticide Programs: http://www.epa.gov/pesticides/
  • Beyond Pesticides—National Coalition Against the Misuse of Pesticides. http://www.beyondpesticides.org/

Water Resources

Water Conservation Issue

Conserving water saves energy and money and preserves fresh water habitat. Much energy goes into transporting water to your residence, and then more is used to heat water for bathroom and kitchen uses. By conserving water it is possible to prevent some of the pollution caused by excessive energy use, such as global warming and acid rain.

Many of the problems relating to water use can be attributed to development in areas where there is an insufficient water supply. For example, although the Southwest has only six percent of the country's fresh water, 31 percent of our water is used to meet the demands of heavy farming and urbanization in this area. As a result, increasing amounts of water are diverted from the Colorado River, and now much less water reaches the sea, but this water is laden with pesticides and fertilizers.

Water diversion often leads to the destruction of wildlife. When rivers shrink, fish can no longer follow their normal paths of migration to spawn and may fail to reproduce. Diverting water also has a heavy impact on our diminishing wetlands, destroying the habitat that supports myriad organisms. In California, huge amounts of water are being diverted from Mono Lake's tributaries to be used in Los Angeles County. Mono Lake's water is naturally very salty, but as increased amounts of fresh water are diverted, the salt content has risen. Soon levels may be too high for brine shrimp to survive. If this happens, the food supply for the millions of birds that use Mono Lake as a stopover in their migration routes will be destroyed.

Much of the water we consume comes from underground reserves. If this water is used faster than it is replenished, it can cause land to sink, a process called subsidence. In Florida a few years ago, houses and cars were swallowed by sinkholes. Once subsidence occurs, the underground aquifers where water was stored cannot be reformed. According to the U.S. Geological Survey, 35 states are pumping groundwater faster than it is being replenished.

STS Actions

  • Show students a glass of water. Ask them to draw a diagram showing where the water originated in their community, what happened to it along the way until it was drawn from the tap. Use the students' ideas to identify misconceptions about water.
  • Have students find out what is the source of drinking water in their community. Have them contact the water department to find out their drinking water is purified. Students should prepare maps to show the sources of water in their community, and charts to describe how water is purified.
  • Take the students to a waste treatment or water purifying plant. Students can investigate the physical, biological and chemical processes used to purify the water.
  • Have students investigate how water is used (and conserved?) in their school. Have them inspect faucets, toilets, and water usage in the kitchen. Have them draw up a list of recommendations for the school to carry out a water conservation program. Challenge them to develop an implementation plan.
For further information consult:

  • Rocky Mountain Institute: http://www.rmi.org/. The Institute fosters the efficient and restorative use of resources to create a more secure, prosperous, and life-sustaining world. In addition to research on water resources, you will find information on energy, buildings and land, communities, climate, transportation, and other issues such as forestry, biotechnology and global security.
  • EPA Water Homepage: http://www.epa.gov/OW/index.html. At this site you'll find resources on groundwater, water science, wastewater management, wetlands, oceans and watersheds, as well links to pages containing classroom activities.

Utilization of Natural Resources

Tropical Rainforests Issue

Tropical rainforests are broad-leafed evergreen woodlands that receive at least 100 inches of rain annually. Rainforests once covered about 5 billion acres in the tropics. As a result of human interference, only half of the original rainforests exist today. Nevertheless, they are home to at least 5 to 10 million species of plants and animals approximately one half of Earth's life forms. Remaining rainforests are disappearing at a rate of 100 acres per minute, an area the size of Kansas every year.

Many natural resources and much of our food come from tropical rainforests. Rainforests serve as a genetic pool for many fruits and vegetables, and new varieties continue to be discovered. Only 1 percent of the tropical rainforest plants that have been identified have been scientifically analyzed, yet they are the source of more than a quarter of the medical compounds sold on the market today.

Nearly the entire acreage of tropical rainforests lies within the borders of developing countries. Often the governments of these countries are encouraged to exploit the resources of their forests to pay off foreign loans. External financial pressures have forced them to sacrifice long-term sustainability to service short-term national debt. Population growth and inequitable distribution of land have further contributed to the problem.

Each year millions of acres of tropical rainforests are burned to make way for agriculture, much of it for export. The nutrients of the rainforest are stored in its multi-layered canopy. When forests are burned, these nutrients mix with the barren topsoil, where they are quickly eroded by rain. When the land is depleted of nutrients, the farmer moves on and clears more rainforest.

In Central America the primary motive for clearing rainforest is to make way for cattle ranching. Most of the beef, however, is produced for export to developed countries to be used by fast food restaurants. Over 120 million pounds of beef are imported by the United States from Central America annually.

According to the World Bank and the United Nations Development Programme, at least 12.5 million acres of tropical rainforest are logged every year. Much of this lumber is exported for use in furniture and other hardwood products. Teak, mahogany, rosewood, purpleheart and ramin are some of the more common tropical hardwoods exported by developed countries. The United States imports about 15 percent of the world's hardwood products.

Many acres of rainforest are flooded each year as a result of large hydroelectric projects built to provide energy for large metropolitan areas and for multinational industrial projects. As a result of these hydroelectric projects, thousands of indigenous peoples who have relied upon the sustenance of the rainforests for thousands of years have been relocated, and their cultures destroyed.

Clearing tropical rainforests means destruction of habitat for the millions of species of plants and animals that live in these regions. Furthermore, forests act as a natural store for carbon dioxide the major "greenhouse" gas responsible for global warming. As rainforests are destroyed, carbon dioxide is released into the atmosphere, leading to higher global temperatures. Scientists predict that as global temperatures rise we will face an increase in crop failure, oceans will rise and flood coastal areas, and many species of plants and animals will become extinct.

Two-thirds of the world's fresh water, excluding that which is locked in the polar ice caps, is cycled within tropical rainforest systems. Rainforests absorb this large amount of water, releasing it slowly and evenly through the process of evapotranspiration. But as rainforests are cleared, soils become exposed to heavy rain, leading to flooding and erosion. It is often impossible to re-establish a rainforest once it has been cleared.

STS Actions

  • Provide students with a map of the world and ask them to identify the location of at least one tropical rainforest. Tell them that about 50 acres of rain forest are destroyed each minute (almost 27 million acres per year, equal in size to the state of Pennsylvania). What impact could this deforestation have on?

    1. Earth's temperature
    2. Animal and plant extinction
    3. Amount of carbon dioxide in the atmosphere
    4. Quality of life for people in the tropics.

  • Engage students in a debate regarding this statement made by Randy Hayes, Executive Director, Rainforest Action Network: "We believe that tropical rainforests are one of the most important global ecological issues of our time. These forests are a vital part of the life support systems of the planet. To ensure their survival is to ensure our own survival. If we don't act now they could be gone by the year 2050. We may be the last generation that will have a chance to save the rainforests."

For further information consult:

  • The Rainforest Action Network: http://www.ran.org/. Rainforest Action Network works to protect the Earth's rainforests and support the rights of their inhabitants through education, grassroots organizing, and non-violent direct action.
  • The Gander Academy Rainforest Page: http://www.stemnet.nf.ca/CITE/rforest.htm. This school-based site contains a full spectrum of resources on rainforests including lesson plans and activities.
  • Global Rivers Environmental Education Network. http://www.earthforce.org/section/programs/green. The Global Rivers Environmental Education Network (GREEN) provides youth the educational opportunities to understand, improve and sustain the water resources in their communities.

Environment

The burning of coal, oil and natural gas, according to some scientists, is changing the earth into a planetary hothouse, changing climates worldwide. Coupled with the destruction of huge areas of tropical rainforests, the amount of carbon dioxide and other heat-trapping gases, the Earth is experiencing a change in its average temperature. This phenomenon is better known as global warming, and represents one of the major environmental issues of the century.

Global Warming Issue

Over the past century, the human species has turned the Earth into one huge unplanned experiment. By releasing unprecedented amounts of greenhouse gases (carbon dioxide, methane, chlorofluorocarbons, nitrous oxide and gases that create tropospheric ozone) into the atmosphere, we have in effect, turned up the global thermostat. Greenhouse gases act in a fashion similar to the windshield of a car parked in the sun, allowing light-energy to pass through, but then trapping the re-emitted heat. The greenhouse effect occurs naturally and without it the Earth would be ice-covered and uninhabitable. However, over the past century, human practices have led to an increased buildup of greenhouse gases.

Scientists already have detected a 1 degree F temperature rise, which may be due to the greenhouse effect. They predict a further increase of between 4 and 9 degrees F by the middle of the next century if greenhouse gas emissions grow at expected rates. The 6 warmest years of the century have been in the last ten years, with 2000 and 2001 being the hottest on record. As world population and fossil fuel use grow, greater quantities of greenhouse gases will be released into the atmosphere. Although the U.S. has only 5 percent of the world's population, we are responsible for 25 percent of the carbon dioxide that is released from burning fossil fuels.

Carbon dioxide (which accounts for approximately half of the global warming trend), nitrous oxide and tropospheric ozone are by-products of burning fossil fuels (coal, oil and gas) and wood. It is important to note that burning natural gas releases 70 percent as much carbon dioxide per unit of energy as oil, and half that of coal. Forests and oceans are natural stores for carbon dioxide, but are unable to absorb the quantities currently being emitted. Deforestation releases large quantities of carbon dioxide as well as methane, carbon monoxide, ozone and nitrous oxide. Swamps, cattle, rice paddies, landfills, termites, swamps and fossil fuels also produce methane, which accounts for 18 percent of the greenhouse effects. Chlorofluorocarbons (CFCs), used in refrigerators and air conditioners, as foam blowers, as circuit board cleaners and as aerosol propellants, account for 17 percent of the greenhouse effect.

Scientists predict that as global temperatures rise, life on Earth will face a series of potentially disastrous threats. Precipitation will decline in some areas, leading to crop failure and expanding deserts. Elsewhere, rainfall will increase, causing flooding and erosion. Changes in habitat could lead to mass extinctions of plants and animals that are unable to migrate to more compatible climates. And sea levels will rise, flooding coastal areas and causing salt-water intrusion into coastal aquifers.

STS Actions

  • Ask students to make a diagram showing how they think the following contribute to create the "greenhouse effect": sun, Earth's surface, burning of fossil fuels, atmosphere, and carbon dioxide. Use the results to identify student misconceptions.
  • Ask students to predict how the following human activities would influence the "greenhouse effect:"

    1. Using transportation systems such as high gas mileage cars, public transportation, and bicycles.
    2. Constructing buildings with super insulated material, smaller windows and automated controls for thermostats and lighting.
    3. Using fluorescent lights.
    4. Buying efficient appliances.
    5. Advocating renewable energy such as wind power, small-scale hydro, geothermal and solar.

  • Climate researchers have predicted natural disasters would increase as a result of global warming. In the early eighties they predicted the following phenomena:

    1. Drought in mid-continent areas
    2. More frequent and severe forest fires.
    3. Flooding in India and Bangladesh.
    4. Extended heat waves over large areas.
    5. Super hurricanes

For further information consult:

  • EPA Climate Change Site: http://www.epa.gov/globalwarming/. This EPA site presents information on the very broad issue of climate change and global warming in a way that is accessible and meaningful to all parts of society - communities, individuals, business, public officials and governments.
  • Intergovernmental Panel on Climate Change: http://www.ipcc.ch/. The World Meteorological Organization and the United Nations Environment Programmed to assess research relevant to human-induced climate change established this site. At this site you can retrieve significant reports on climate change.