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- 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 1 Lecture Outline
- 2. Learning Outcomes After studying this chapter, you should be able to answer the following questions: • Describe several of the most important environmental problems facing the world. Are there signs of hope for solving these problems? • What do we mean by sustainability and sustainable development? • Why does science support—but rarely prove—particular theories? • How can scientists know if their research is reliable and important? • How can critical thinking help us understand environmental issues? • Explain how we can use graphs and statistics to answer questions in environmental science. • What are some arguments for conservation or preservation of nature? 1-2
- 3. Today we are faced with a challenge that calls for a shift in our thinking, so that humanity stops threatening its life-support system. –Wangari Maathai, winner of 2004 Nobel Peace Prize 1-3
- 4. 1.1 Understanding Our Environment • The conditions on Earth are unique. • Perfect for the existence of life as we know it. The life sustaining ecosystems on which we all depend are unique in the universe, as far as we know. 1-4
- 5. What is environmental science? • Environmental science is the systematic study of our environment and our place in it. • Because environmental problems are complex, environmental science draws on many fields of knowledge (fig 1.4). 1-5
- 6. 1.2 Environmental Problems and Opportunities • Polluted water contributes to the death of more than 15 million people every year, most of them children under age 5. • Food supplies: currently more than 850 million people are chronically undernourished. • Energy resources: Fossil fuel supplies are diminishing. There are many problems associated with them. 1-6
- 7. Environmental Problems • Climate change: Burning fossil fuels, making cement, cultivating rice paddies, clearing forests, and other human activities release carbon dioxide and other so-called greenhouse gases, which trap heat in the atmosphere. 1-7
- 8. Environmental Problems • Air quality: Air quality has worsened dramatically in many areas • Biodiversity loss: Biologists report that habitat destruction, overexploitation, pollution, and introduction of exotic organisms are eliminating species at a rate comparable to the great extinction that marked the end of the age of dinosaurs. 1.8
- 9. Environmental Problems continued…. • Marine resources: The ocean is an irreplaceable food resource for many people. 1-9
- 10. Environmental Opportunities • Marine resources: Around the world, people who depend on seafood for their livelihood and sustenance are finding that setting aside marine reserves can restore fish populations as well as promote human development. 1-10
- 11. Environmental Opportunities • Population has stabilized in most industrialized countries and even in some very poor countries where social security and democracy have been established. – Over the past 25 years, the average number of children born per woman worldwide has decreased from 6.1 to 2.6 1.11
- 12. Environmental Opportunities continued… • Health: The incidence of life-threatening infectious diseases has been reduced sharply in most countries during the past century, – Life expectancies have nearly doubled, on average. • Conservation of forests and nature preserves: Deforestation has slowed in Asia, from more than 8 percent during the 1980s to less than 1 percent in the 1990s. 1-12
- 13. Environmental Opportunities • Renewable energy: Encouraging progress is being made in a transition to renewable energy sources. – The European Union has announced a goal of obtaining 22 percent of its electricity and 12 percent of all energy from renewable sources by 2010. • Information: The increased speed at which information and technology now flow around the world holds promise that we can continue to find solutions to our environmental dilemmas. 1.13
- 14. 1.3 Human Dimensions of Environmental Science 1-14
- 15. Sustainability is a central theme • Sustainability is a search for ecological stability and human progress that can last over the long term. • Sustainable development is “meeting the needs of the present without compromising the ability of future generations to meet their own needs.” 1-15
- 16. Indigenous peoples are guardians of much of the world’s biodiversity • Often, the 500 million indigenous people who remain in traditional homelands still possess valuable ecological wisdom and remain the guardians of little- disturbed habitats 1-16
- 17. 1.4 Science Helps Us Understand Our Environment 1-17
- 18. 1-18
- 19. Deductive and inductive reasoning are both useful • Logical reasoning from general to specific is known as deductive reasoning. • Reasoning from many observations to produce a general rule is inductive reasoning. 1-19
- 20. The scientific method is an orderly way to examine problems • 1. Observe that your flashlight doesn’t light; also, there are three main components of the lighting system (batteries, bulb, and switch). • 2. Propose a hypothesis, a testable explanation: “The fl ashlight doesn’t work because the batteries are dead.” • 3. Develop a test of the hypothesis and predict the result that would indicate your hypothesis was correct: “I will replace the batteries; the light should then turn on.” • 4. Gather data from your test: After you replaced the batteries, did the light turn on? • 5. Interpret your results: If the light works now, then your hypothesis was right; if not, then you should formulate a new hypothesis, perhaps that the bulb is faulty, and develop a new test for that hypothesis. 1-20
- 21. Understanding probability helps reduce uncertainty • Probability is a measure of how likely something is to occur. 1-21
- 22. Experimental Design • A natural experiment, is one that involves observation of events that have already happened. • Manipulative experiments have conditions deliberately altered, and all other variables are held constant. • Blind experiments are often used, in which the researcher doesn’t know which group is treated until after the data have been analyzed. • In health studies, such as tests of new drugs, double- blind experiments are used, in which neither the subject (who receives a drug or a placebo) nor the researcher knows who is in the treatment group and who is in the control group.1-22
- 23. What is sound science? 1-23
- 25. 1.6 A Brief History of Conservation and Environmental Thought 1-25
- 26. Rising pollution levels led to the modern environmental movement • The tremendous expansion of chemical industries during and after World War II added a new set of concerns to the environmental agenda. • Silent Spring, written by Rachel Carson (fig. 1.24a) and published in 1962, awakened the public to the threats of pollution and toxic chemicals to humans as well as other species. 1-26
- 27. Practice Quiz 1. Describe how fishing has changed at Apo Island, and the direct and indirect effects on people’s lives. 2. What are some basic assumptions of science? 3. Distinguish between a hypothesis and a theory. 4. Describe the steps in the scientific method. 5. What is probability? Give an example. 6. What does significance mean in statistics? 7. What’s the first step in critical thinking according to table 1.4? 8. Distinguish between utilitarian conservation and biocentric preservation. Name two environmental leaders associated with each of these philosophies. 9. Why do some experts regard water as the most critical natural resource for the twenty-first century? 10. Where in figure 1.7 do the largest areas of persistence of greening occur? What is persistence of greening? 11. Describe some signs of hope in overcoming global environmental problems. 12. What is the link between poverty and environmental quality? 13. Define sustainability and sustainable development. 1-27
Notas do Editor
- In this chapter and throughout this book, you will read about many cases in which humans have caused serious environmental problems. You will also read about promising, exciting solutions to many of these problems. Your task as a student of environmental science is to gain an idea of what some of the larger current problems are, what some solutions might be, and how you might use knowledge from a variety of disciplines—from biology and chemistry to economics—to develop tomorrow’s strategies for more sustainable living on our planet.
- What does this statement mean? Can you give some examples?
- Imagine that you are an astronaut returning to the earth after a long trip to the moon or Mars. What a relief it would be, after experiencing the hostile environment of outer space, to come back to this beautiful, bountiful planet (fig. 1.2). Although there are dangers and difficulties here, we live in a remarkably prolific and hospitable world that is, as far as we know, unique in the universe. Compared with the conditions on other planets in our solar system, temperatures on the earth are mild and relatively constant. Plentiful supplies of clean air, fresh water, and fertile soil are
- Sciences such as biology, chemistry, earth science, and geography provide important information. Social sciences and humanities, from political science and economics to art and literature, help us understand how society responds to environmental crises and opportunities. Environmental science is also mission oriented, we all have a responsibility to try to do something about the problems we have created.
- Clean water: At least 1.1 billion people lack access to safe drinking water, and twice that many don’t have adequate sanitation. Food supplies: In a world of food surpluses, currently more than 850 million people are chronically undernourished, and at least 60 million face acute food shortages due to bad weather or politics Energy resources: Fossil fuels (oil, coal, and natural gas) presently provide around 80 percent of the energy used in industrialized countries. Supplies of these fuels are diminishing, however, and problems associated with their acquisition and use—air and water pollution, mining damage, shipping accidents, and geopolitics—may limit what we do with remaining reserves. Cleaner, renewable energy resources—solar, wind, geothermal, and biomass power—together with conservation could give us cleaner, less destructive options
- Climate change: Burning fossil fuels, making cement, cultivating rice paddies, clearing forests, and other human activities release carbon dioxide and other so-called greenhouse gases, which trap heat in the atmosphere. Over the past 200 years, atmospheric CO2 concentrations have increased about 30 percent. Climatologists warn that by 2100, if current trends continue, mean global temperatures will probably warm between 1.5 and 6C (2.7 and 11F). Biodiversity loss: Biologists report that habitat destruction, overexploitation, pollution, and introduction of exotic organisms are eliminating species at a rate comparable to the great extinction that marked the end of the age of dinosaurs
- Air quality: Air quality has worsened dramatically in many areas. Over southern Asia, for example, satellite images recently revealed a 3-km (2-mile)-thick toxic haze of ash, acids, aerosols, dust, and photochemical products, which regularly covers the entire Indian subcontinent for much of the year. Biodiversity loss: Biologists report that habitat destruction, overexploitation, pollution, and introduction of exotic organisms are eliminating species at a rate comparable to the great extinction that marked the end of the age of dinosaurs
- More than a billion people in developing countries depend on seafood for their main source of animal protein, but most commercial fisheries around the world are in steep decline (fig. 1.8). According to the World Resources Institute, more than three-quarters of the 441 fish stocks for which information is available are severely depleted or in urgent need of better management. Canadian researchers estimate that 90 percent of all the large predators, including bluefin tuna, marlin, swordfish, sharks, cod, and halibut, have been removed from the ocean.
- Marine Resources: Showing that these projects can be ecologically sound, economically sustainable, and socially acceptable on the local scale can lead to wider applications. Marine reserves are being established to protect reproductive areas in California, Hawaii, New Zealand, Great Britain, and many other areas, in addition to the Philippines.
- Population: By 2050, the UN Population Division predicts, all developed countries and 75 percent of the developing world will experience a below-replacement fertility rate of 2.1 children per woman. This suggests that the world population will stabilize at about 8.9 billion, rather than the 9.3 billion previously estimated.
- Affluence also has environmental costs The affluent lifestyle that many of us in the richer countries enjoy consumes an inordinate share of the world’s natural resources and produces a shockingly high proportion of pollutants and wastes. The United States, for instance, with less than 5 percent of the total population, consumes about one-quarter of most commercially traded commodities, such as oil, and produces a quarter to half of most industrial wastes, such as greenhouse gases, pesticides, and other persistent pollutants. To get an average American through the day takes about 450 kg (nearly 1,000 lbs) of raw materials, including 18 kg (40 lbs) of fossil fuels, 13 kg (29 lbs) of other minerals, 12 kg (26 lbs) of farm products, 10 kg (22 lbs) of wood and paper, and 450 liters (119 gal) of water. Every year, Americans throw away some 160 million tons of garbage, including 50 million tons of paper, 67 billion cans and bottles, 25 billion styrofoam cups, 18 billion disposable diapers, and 2 billion disposable razors (fig. 1.11).
- Of course, neither ecological systems nor human institutions can continue forever. We can work, however, to protect the best aspects of both realms, and to encourage resiliency and adaptability in both of them. World Health Organization Director Gro Harlem Brundtland has defined sustainable development as “meeting the needs of the present without compromising the ability of future generations to meet their own needs.” In these terms, development means bettering people’s lives. Sustainable development, then, means progress in human well-being that we can extend or prolong over many generations, rather than just a few years. To be truly enduring, the benefits of sustainable development must be available to all humans and not just to the members of a privileged group. We will discuss this topic further in chapter 14.
- In both rich and poor countries, native or indigenous people are generally the least powerful, most neglected groups in the world. Typically descendants of the original inhabitants of an area taken over by more powerful outsiders, they are distinct from their country’s dominant language, culture, religion, and racial communities. In his book The Future of Life, the eminent ecologist E. O. Wilson argues that the cheapest and most effective way to preserve species is to protect the natural ecosystems in which they now live. Cultural diversity and biodiversity often go hand in hand. Seven of the countries with the highest cultural diversity in the world are also on the list of “megadiversity” countries with the highest number of unique biological organisms (listed in decreasing order of importance). Source: Norman Myers, Conservation International and Cultural Survival Inc., 2002.
- What is science? Science (from scire, “to know” in Latin) is a process for producing empirical knowledge by observing natural phenomena. We develop or test theories (proposed explanations of how a process works) using these observations. “Science” also refers to the cumulative body of knowledge produced by many scientists. Science is valuable because it helps us understand the world and meet practical needs, such as finding new medicines, new energy sources, or new foods. In this section, we’ll investigate how and why science follows standard methods. Science rests on the assumption that the world is knowable and that we can learn about it by careful observation and logical reasoning (table 1.2).
- Because bias and methodical errors are hard to avoid, scientific tests are subject to review by informed peers, who can evaluate results and conclusions (fig. 1.16). The peer review process is an essential part of ensuring that scientists maintain good standards in study design, data collection, and interpretation of results.
- Ideally, scientists deduce conclusions from general laws that they know to be true. For example, if we know that massive objects attract each other (because of gravity), then it follows that an apple will fall to the ground when it releases from the tree. This logical reasoning from general to specific is known as deductive reasoning. Often, however, we do not know general laws that guide natural systems. We observe, for example, that birds appear and disappear as a year goes by. Through many repeated observations in different places, we can infer that the birds move from place to place. We can develop a general rule that birds migrate seasonally. Although deductive reasoning is more logically sound than inductive reasoning, it only works when our general laws are correct. We often rely on inductive reasoning to understand the world because we have few immutable laws. Sometimes it is insight, as much as reasoning, that leads us to an answer. Many people fail to recognize the role that insight, creativity, and luck play in research. Some of our most important discoveries were made because the investigators were passionately interested in their topics and pursued hunches that appeared unreasonable to fellow scientists. A good example is Barbara McClintock, the geneticist who discovered that genes in corn can move and recombine spontaneously. Where other corn geneticists saw random patterns of color and kernel size, McClintock’s years of experience in corn breeding and an uncanny ability to recognize patterns, led her to guess that genes could recombine in ways that no one had previously imagined.
- You may already be using the scientific method without being aware of it. Suppose you have a flashlight that doesn’t work. The flashlight has several components (switch, bulb, batteries) that could be faulty. If you change all the components at once, your flashlight might work, but a more methodical series of tests will tell you more about what was wrong with the system—knowledge that may be useful next time you have a faulty flashlight. So you decide to follow the standard scientific steps. In systems more complex than a flashlight, it is almost always easier to prove a hypothesis wrong than to prove it unquestionably true. This is because we usually test our hypotheses with observations, but there is no way to make every possible observation. The philosopher Ludwig Wittgenstein illustrated this problem as follows: Suppose you saw hundreds of swans, and all were white. These observations might lead you to hypothesize that all swans were white. You could test your hypothesis by viewing thousands of swans, and each observation might support your hypothesis, but you could never be entirely sure that it was correct. On the other hand, if you saw just one black swan, you would know with certainty that your hypothesis was wrong. As you’ll read in later chapters, the elusiveness of absolute proof is a persistent problem in environmental policy and law. You can never absolutely prove that the toxic waste dump up the street is making you sick. The elusiveness of proof often decides environmental liability lawsuits.
- One strategy to improve confidence in the face of uncertainty is to focus on probability. Usually, probability estimates are based on a set of previous observations or on standard statistical measures. Probability does not tell you what will happen, but it tells you what is likely to happen. If you hear on the news that you have a 20 percent chance of catching a cold this winter, that means that 20 of every 100 people are likely to catch a cold. This doesn’t mean that you will catch one. In fact, it’s more likely that you won’t catch a cold than that you will. If you hear that 80 out of every 100 people will catch a cold, you still don’t know whether you’ll get sick, but there’s a much higher chance that you will.
- The study of colds and sleep deprivation is an example of an observational experiment, one in which you observe natural events and interpret a causal relationship between the variables. This kind of study is also called a natural experiment, one that involves observation of events that have already happened. Other scientists can use manipulative experiments, in which conditions are deliberately altered, and all other variables are held constant. Most manipulative experiments are done in the laboratory, where conditions can be carefully controlled. Suppose you were interested in studying whether lawn chemicals contributed to deformities in tadpoles. You might keep two groups of tadpoles in fish tanks, and expose one to chemicals. In the lab, you could ensure that both tanks had identical temperatures, light, food, and oxygen. By comparing a treatment (exposed) group and a control (unexposed) group, you have also made this a controlled study. Often, there is a risk of experimenter bias. Suppose the researcher sees a tadpole with a small nub that looks like it might become an extra leg. Whether she calls this nub a deformity might depend on whether she knows that the tadpole is in the treatment group or the control group. To avoid this bias, blind experiments are often used, in which the researcher doesn’t know which group is treated until after the data have been analyzed. In health studies, such as tests of new drugs, double-blind experiments are used, in which neither the subject (who receives a drug or a placebo) nor the researcher knows who is in the treatment group and who is in the control group. In each of these studies there is one dependent variable and one, or perhaps more, independent variables. The dependent variable, also known as a response variable, is affected by the independent variables. In a graph, the dependent variable is on the vertical (Y) axis, by convention. Independent variables are rarely really independent (they are affected by the same environmental conditions as the dependent variable, for example). Many people prefer to call them explanatory variables, because we hope they will explain differences in the dependent variable.
- If you see claims of sound science and junk science, how can you evaluate them? How can you identify bogus analysis that is dressed up in quasi-scientific jargon but that has no objectivity? This is such an important question that astronomer Carl Sagan has proposed a “Baloney Detection Kit” (table 1.3) to help you out.
- Notice that many critical thinking processes are self- reflective and self-correcting. This form of thinking is sometimes called “thinking about thinking.” It is not critical in the sense of finding fault, but it makes a conscious, active, disciplined effort to be aware of hidden motives and assumptions; to uncover bias; and to recognize the reliability or unreliability of sources.
- We can divide conservation history and environmental activism into at least four distinct stages: (1) pragmatic resource conservation, (2) moral and aesthetic nature preservation, (3) a growing concern about health and ecological damage caused by pollution, and (4) global environmental citizenship. These stages aren’t necessarily mutually exclusive. Parts of each persist today in the environmental movement, and one person may embrace them all simultaneously. Resource waste triggered pragmatic resource conservation Many historians consider the publication of Man and Nature in 1864 by geographer George Perkins Marsh as the wellspring of environmental protection in North America. Marsh, who also was a lawyer, politician, and diplomat, traveled widely around the Mediterranean as part of his diplomatic duties in Turkey and Italy. He read widely in the classics (including Plato) and personally observed the damage caused by excessive grazing by goats and sheep and by the deforestation of steep hillsides. Alarmed by the wanton destruction and profligate waste of resources still occurring on the American frontier in his lifetime, he warned of its ecological consequences. Largely because of his book, national forest reserves were established in the United States in 1873 to protect dwindling timber supplies and endangered watersheds. Among those influenced by Marsh’s warnings were U.S. President Theodore Roosevelt and his chief conservation adviser, Gifford Pinchot (fig. 1.22 a and b). Together with naturalists and activists such as John Muir, Roosevelt and Pinchot established the framework of the national forest, park, and wildlife refuge system. They passed game protection laws and tried to stop some of the most flagrant abuses of the public domain. Pinchot also was governor of Pennsylvania and founding head of the Tennessee Valley Authority, which provided inexpensive power to the southeastern United States. The basis of Roosevelt’s and Pinchot’s policies was pragmatic utilitarian conservation. They argued that the forests should be saved “not because they are beautiful or because they shelter wild creatures of the wilderness, but only to provide homes and jobs for people.” Resources should be used “for the greatest good, for the greatest number, for the longest time.” Ethical and aesthetic concerns inspired the preservation movement John Muir (fig. 1.22c), amateur geologist, popular author, and first president of the Sierra Club, strenuously opposed Pinchot’s utilitarian policies. Muir argued that nature deserves to exist for its own sake, regardless of its usefulness to us.
- The tremendous expansion of chemical industries during and after World War II added a new set of concerns to the environ mental agenda. Silent Spring, written by Rachel Carson (fig. 1.24a) and published in 1962, awakened the public to the threats of pollution and toxic chemicals to humans as well as other species. The movement she engendered might be called modern environmentalism because its concerns extended to include both natural resources and environmental pollution. Under the leadership of a number of brilliant and dedicated activists and scientists, the environmental agenda was expanded in the 1970s, to most of the issues addressed in this textbook, such as human population growth, atomic weapons testing and atomic power, fossil fuel extraction and use, recycling, air and water pollution, and wilderness protection. Environmentalism has become well established in the public agenda since the first national Earth Day in 1970. A majority of Americans now consider themselves environmentalists, although there is considerable variation in what that term means.