I. Human Population

            A. Population Growth

                        1. Many environmental problems loom large and seem urgent today because of the rapid increase in human population.

                        2. The huge numbers of humans on Earth are making enormous demands on the planet.

                        3. If our current birthrates are maintained, our population will double in less than one hundred years.

                        4. An important factor in determining population growth is the deathrate, which has decreased worldwide.

            B. Effects of Lifestyles

                        1. The lifestyle of a population also contributes to the extraordinary environmental demands made on the Earth.

                        2. The population of the United States has stabilized at a low level, but we use more energy and more natural resources than any other country in the world.

                        3. Natural resources are consumed in the production and use of luxury goods.

II. Pollution

                        1. Materials released into the environment fall into two broad categories: biodegradable and non biodegradable.

                        2. Biodegradable materials are materials that can be degraded, or broken down, by microorganisms into the essential nutrients from which they  were made.

                        3. Nonbiodegradable materials cannot be broken down by natural processes or are broken down only very slowly.

            A. Biological Magnification

                        1. Sometimes pollutants affect the biosphere in ways no one expects.

                        2. Biological magnification is the amount of compounds in when each organism in a food chain increases.

                        3. Biological magnification occurs with many pesticides and industrial  waste products.

            B. Air Pollution

                        1. A dirty brown haze that contains different pollutants in different places.

                        2. Temperature inversions are when cooler air is trapped below warmer air and pollution is pushed towards the ground.

                        3. Acid rain has numerous and serious effect on the environment.

                        4. The green house effect is when carbon dioxide and other gases in the  atmosphere absorb heat energy forming a kind of “heat blanket” around earth.

                        5. Holes in the ozone layer are not actual holes but rather areas where little ozone is found.

            C. Water Pollution

                        1. In the United States, billions of liters of fresh water are used daily.

                        2. Water is used for drinking, cooking, bathing, and cleaning.

                        3. Although water is a renewable resource, there is a limited amount of fresh water.

                        4. The most common sources of water pollution are chemical wastes, raw sewage, and high temperatures.

                        5. Thermal pollution is heated water that kills aquatic plants and animals.

III. The Fate of the Earth

            A. Forests

                        1. The survival of humans and human society depends upon the survival of other organisms in the biosphere.

                        2. When forests are carelessly cut down, many important changes occur, including the structure of the soil and the death of many microorganisms.

                        3. Programs that plant new trees when old trees are cut down are called reforestation programs.

            B. Endangered Species

                        1. When an animal or plant species becomes so rare that it is threatened with extinction, it is called an endangered species.

                        2. With few individuals of a species remaining, a harsh winter, a disease epidemic, or any other natural disaster can mean extinction.  Some species can become endangered if they are able to survive in only one particular habitat.

                        3. Today, one plant or animal species becomes extinct every hour.

            C. Why Save Endangered Species?

                        1. Once a species becomes extinct, it will never exist again.

                        2. Many everyday foods, medicines, and industrial compounds come from wild plant and animal species.

                        3. Many animal species produce compounds that may prove important to human health.

            D. Food from Plants

                        1. Most of the world’s population obtains its food from crops grown on farms.

                        2. The crop plants grown in the United States today are the results of generations of selective breeding.

                        3. If only a single variety of plant is planted in huge numbers, entire croplands can be destroyed by a single disease.

IV. The Future of the Biosphere

            A. Actions for Conservation

                        1. Happily, there are people in the world who love wild places, wild plants, and wild animals.

                        2. Towns, counties, states, the federal government, and conservancy groups have all purchased land that is to be set aside for conservation purposes.

                        3. It is more difficult to conserve the resources of the ocean, as ocean currents ravel all over the world.

            B. Difficult Decisions

                        1. Cleaning up the environment and keeping it clean are not easy jobs.

                        2. Recycling is when certain kinds of solid wastes – newspapers, bottles, and metal or plastic cans, can be processed and used again.

                        3. You must decide how important the environment is and whether you are willing to pay to keep it healthy.