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Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep

The Environment Chapter 18 Table of Contents Section 1 Global Change Section 2 Effects on Ecosystems Section 3 Solving Environmental Problems

Section 1 Global Change Chapter 18 Objectives • Recognizethe causes and effects of acid rain. • Evaluatethe long-term consequences of atmospheric ozone depletion. • Explainhow the burning of fossil fuels has changed the atmosphere. • Analyzethe proposed relationship between the greenhouse effect and global warming.

Section 1 Global Change Chapter 18 The Atmosphere and Ecosystems Acid Rain • Human-induced environmental changes are affecting ecosystems worldwide and may lead to global change. • Sulfur introduced into the atmosphere by smokestacks can combine with water vapor to produce sulfuric acid. • The sulfuric acid is carried back to Earth’s surface in acidified precipitation is called acid rain.

Section 1 Global Change Chapter 18 The Atmosphere and Ecosystems, continued Acid Rain • Research suggests that the acid in precipitation added by human activity is having a dramatic effect. • In the United States and Canada, thousands of lakes are “dying” as their pH levels fall below 5.0. • Forests in the eastern United States and southern Canada are also being damaged.

Section 1 Global Change Chapter 18 Acid Precipitation

Section 1 Global Change Chapter 18 The Ozone Layer The Ozone Hole • In 1985, a researcher in Antarctica noticed that ozone levels in the atmosphere seemed to be as much as 35 percent lower than the average values during the 1960s. • Alarmed, scientists examined satellite images taken in previous years. They found that the disintegration of the Earth’s ozone shield was evident as far back as 1978. • Every year since then, more ozone has disappeared, and the ozone hole has grown larger.

Section 1 Global Change Chapter 18 Ozone “Hole” over Antarctica

Section 1 Global Change Chapter 18 The Ozone Layer, continued The Ozone Hole • Because the decrease in ozone allows more ultraviolet radiation to reach the Earth’s surface, scientists expect an increased incidence of diseases caused by exposure to ultraviolet radiation. • In fact, in the United States, the number of cases of malignant melanoma, a potentially lethal form of skin cancer, has almost doubled since 1980.

Section 1 Global Change Chapter 18 Ozone and Ecosystems Click below to watch the Visual Concept. Visual Concept

Section 1 Global Change Chapter 18 The Ozone Layer, continued What Is Destroying Ozone? • The major cause of ozone destruction is a class of chemicals called chlorofluorocarbons (CFCs). • High in the atmosphere, ultraviolet radiation from the sun is able to break the usually stable bonds in CFCs. The resulting free chlorine atoms then enter into a series of reactions that destroys ozone. • Today many countries limit or ban the use of CFCs.

Section 1 Global Change Chapter 18 Global Temperatures • The average global temperature has been steadily increasing for more than a century, particularly since the 1950s. • In Earth’s long history there have been many such periods ofglobal warming,often followed by centuries of cold. • Many scientists suspect, however, that human activity may be significantly contributing to global warming in modern times.

Section 1 Global Change Chapter 18 Change in Global Temperature

Section 1 Global Change Chapter 18 Global Temperatures, continued The Greenhouse Effect • The chemical bonds in carbon dioxide molecules absorb solar energy as heat radiates from Earth. • This process, called the greenhouse effect, traps heat within the atmosphere in the same way glass traps heat within a greenhouse. • There has been a large increase in carbon dioxide in the Earth’s atmosphere in recent times, which seems to be related to the burning of fossil fuels that has accompanied clearing of forests.

Section 1 Global Change Chapter 18 The Greenhouse Effect

Section 1 Global Change Chapter 18 The Greenhouse Effect Click below to watch the Visual Concept. Visual Concept

Section 1 Global Change Chapter 18 Global Temperatures, continued Is Global Warming Occurring? • The correlation of increasing global temperatures with increasing carbon dioxide levels is very close. • In science, however, correlation does not prove cause and effect. Both global temperature and levels of greenhouse gases may be changing because of other variables that have not been recognized yet. • However, many scientists are convinced temperature and carbon dioxide levels are related.

Section 1 Global Change Chapter 18 Atmospheric Temperature and CO2 Levels

Section 1 Global Change Chapter 18 Global Warming Click below to watch the Visual Concept. Visual Concept

Section 2 Effects on Ecosystems Chapter 18 Objectives • Describethe effects of chemical pollutants on the environment. • Identifythree nonrenewable resources. • Predictthe potential consequences of uncontrolled population growth. • Contrastpopulation growth in developing countries with that in industrialized countries.

Section 2 Effects on Ecosystems Chapter 18 Effects of Chemical Pollution • One important urban environmental problem is chemical pollution. • In a highly publicized example of pollution, a very large oil tanker ran aground off the coast of Alaska in 1989. Oil from the tanker heavily polluted 1,600 km (1,000 mi) of coastline and injured or killed thousands of marine animals. • Many of the most disastrous incidents of pollution involve industrial chemicals that are toxic or carcinogenic (cancer-causing).

Section 2 Effects on Ecosystems Chapter 18 Effects of Chemical Pollution, continued Agricultural Chemicals • In many countries, modern agriculture introduces large amounts of chemicals into the global ecosystem. • These chemicals include pesticides, herbicides, and fertilizers. • Industrialized countries, like the United States, now attempt to carefully monitor side effects of these chemicals.

Section 2 Effects on Ecosystems Chapter 18 Effects of Chemical Pollution, continued Agricultural Chemicals: Pesticides • Molecules of chlorinated hydrocarbons—a class of compounds that includes the pesticides DDT, chlordane, lindane, and dieldrin—break down slowly in the environment. • As these molecules pass up through the trophic levels of the food chain, they become increasingly concentrated. This process is called biological magnification.

Section 2 Effects on Ecosystems Chapter 18 Biological Magnification of DDT

Section 2 Effects on Ecosystems Chapter 18 Biological Magnification of Toxins Click below to watch the Visual Concept. Visual Concept

Section 2 Effects on Ecosystems Chapter 18 Loss of Resources Extinction of Species • Earth is losing many species. Some 10 percent of well-known species teeter on the brink of extinction. • Worst-case estimates are that we will lose up to one-fifth of the world’s species of plants and animals—about 1 million species—during the next 50 years. • An extinction of this size has not occurred in at least 65 million years, since the end of the age of dinosaurs.

Section 2 Effects on Ecosystems Chapter 18 Loss of Resources, continued Loss of Topsoil • The United States is one of the most productive agricultural countries on Earth, largely because of its fertile soils. • This rich topsoil cannot be replaced, and it is being lost at a rate of several centimeters each decade. • Turning over the soil to eliminate weeds, allowing animals to overgraze ranges and pastures, and practicing poor land management all permit wind and rain to remove more and more of the topsoil.

Section 2 Effects on Ecosystems Chapter 18 Loss of Resources, continued Ground-Water Pollution and Depletion • A third resource that we cannot replace is ground water. • Much ground water is stored within porous rock reservoirs called aquifers. • A great deal of ground water is being polluted by irresponsible disposal of chemical wastes. Once pollution enters the ground water, there is no effective way to remove it.

Section 2 Effects on Ecosystems Chapter 18 Loss of Resources, continued Ground-Water Pollution and Depletion • Large amounts of ground water are being removed from many aquifers far faster than natural processes can replenish it.

Section 2 Effects on Ecosystems Chapter 18 Aquifer Recharge Zone

Section 2 Effects on Ecosystems Chapter 18 Growth of the Human Population The human population is rapidly growing.

Section 2 Effects on Ecosystems Chapter 18 Human Population Click below to watch the Visual Concept. Visual Concept

Section 2 Effects on Ecosystems Chapter 18 Growth of the Human Population, continued Worldwide Rates of Growth • The world’s population exceeded 6 billion in October 1999, and the annual increase is now about 94 million people. • Population growth is fastest in the developing countries. It is slowest in the industrialized countries. • The United Nations projects that the world’s population will stabilize at 9.7 billion by the year 2050.

Section 2 Effects on Ecosystems Chapter 18 World Population Growth Patterns

Section 3 Solving Environmental Problems Chapter 18 Objectives • Describetwo effective approaches that have been taken to reduce pollution in the United States and abroad. • Evaluatethe five major steps necessary to solve environmental problems. • Determinehow individuals can take personal action to help solve environmental problems.

Section 3 Solving Environmental Problems Chapter 18 A Worldwide Effort • As human activities continue to place severe stresses on ecosystems, worldwide attention must be focused on solving these problems. • One of the most encouraging developments of the early 1990s was the global increase in efforts to reduce pollution. • International agreements to stop CFC production are one example. A great deal of progress has also been made in reducing air and water pollution.

Section 3 Solving Environmental Problems Chapter 18 A Worldwide Effort, continued In the United States • Two effective approaches have been taken to reduce pollution in the United States. • The first approach has been to pass laws forbidding it. • A second effective approach to reducing pollution has been to make it more expensive by placing a tax on it.

Section 3 Solving Environmental Problems Chapter 18 Solving Environmental Problems Five Steps to Success • There are five components to successfully solving any environmental problem: 1. Assessment: The first stage is scientific analysis of the problem, the gathering of information about what is happening. 2. Risk analysis: Using the information obtained by scientific analysis, scientists predict the consequences of different types of environmental intervention.

Section 3 Solving Environmental Problems Chapter 18 Solving Environmental Problems, continued Five Steps to Success 3. Public education: When it is possible to describe alternative courses of action, the public must be informed. 4. Political action: The public, through its elected officials, selects and implements a course of action. 5. Follow-through: The results of any action should be carefully monitored to see if the environmental problem is being solved.

Section 3 Solving Environmental Problems Chapter 18 Solving Environmental Problems, continued Two Success Stories: The Nashua River • Running through the heart of New England, the Nashua River was severely polluted by mills established in Massachusetts in the early 1900s. • The Nashua River Cleanup Committee presented bottles of dirty river water to politicians, spoke at town meetings, recruited business people to help finance a waste treatment plant, and began to clean garbage from the Nashua River’s banks. • Industrial dumping into the river is now banned, and the river has largely recovered.

Section 3 Solving Environmental Problems Chapter 18 Solving Environmental Problems, continued Two Success Stories: Lake Washington • Lake Washington was being polluted with nitrogen and phosphorous from 10 municipal sewage plants. • An ecology professor at the University of Washington in Seattle, W. T. Edmondson, became alarmed and began a campaign in 1956 to educate public officials about the danger. • After five years, as a direct result of his efforts, joint municipal taxes financed the cleanup of Lake Washington with a massive trunk sewer that rings the lake and carries treated discharge far out into Puget Sound.

Section 3 Solving Environmental Problems Chapter 18 Solving Environmental Problems, continued Your Contribution • You can save energy by walking, riding a bicycle, or taking public transportation to work or school. • Newspapers, aluminum products, glass containers, and many plastic containers can be recycled. • A resource- and energy-use inventory of your home can identify additional ways to help the environment.

Section 3 Solving Environmental Problems Chapter 18 Recycling

Section 3 Solving Environmental Problems Chapter 18 Conservation Click below to watch the Visual Concept. Visual Concept

Standardized Test Prep Chapter 18 Multiple Choice Use the chart below to answer questions 1–3.

Standardized Test Prep Chapter 18 Multiple Choice, continued 1. How much grain was produced per person in 1990? A. 280 kg B. 305 kg C. 320 kg D. 360 kg

Standardized Test Prep Chapter 18 Multiple Choice, continued 2. How have world grain production and the human population changed since the early 1980s? F. World grain production has increased; the human population has decreased. G. Both have decreased. H. World grain production has increased more rapidly than the human population. J. The human population has increased more rapidly than world grain production.

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