1. Science and the Environment
Topic:
Science and the Environment

2. Learning Outcomes As a result of this topic, the student will …
Describe several important environmental problems facing
the world.
List several examples of progress in environmental quality.
Explain the idea of sustainability and some of its aims.
Why are scientists cautious about claiming absolute proof
of particular theories?
What is critical thinking, and why is it important in environmental science?
Why do we use graphs and data to answer questions in science?
Identify several people who helped shape our ideas of resource conservation and preservation—why did they
promote these ideas when they did?
1-2

3. –Wangari Maathai, winner of 2004 Nobel Peace Prize
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
What does this statement mean? Can you give some examples?
1-3 3

4. Case Study: Saving the Reefs of Apo Island
Thirty years ago, this island, like many others in the Philippines, suffered a catastrophic decline in the seafood that was the mainstay of their diet and livelihood. Rapid population growth coupled with destructive fishing methods such as dynamite or cyanide fishing, small mesh gill nets, deep-sea trawling, and muroami (a technique in which fish are chased into nets by pounding on coral with weighted lines) had damaged the reef habitat and exhausted fish stocks. In 1979, scientists from Silliman University on nearby Negros Island visited Apo to explain how establishing a marine sanctuary could help reverse this decline. The coral reef fringing the island acts as a food source and nursery for many of the marine species sought by fishermen. Protecting that breeding ground, they explained, is the key to preserving a healthy fishery. The scientists took villagers from Apo to the uninhabited Sumilon Island, where a no-take reserve was teeming with fish. After much discussion, several families decided to establish a marine sanctuary along a short section of Apo Island shoreline. Initially, the area had high-quality coral but few fish. The participating families took turns watching to make sure that no one trespassed in the no fishing zone. Within a few years, fish numbers and sizes in the sanctuary increased dramatically, and “spillover” of surplus fish led to higher catches in surrounding areas. In 1985, Apo villagers voted to establish a 500 m (0.3 mi) wide marine sanctuary around the entire island. Fishing is now allowed in this reserve, but only by low- impact methods such as hand-held lines, bamboo traps, large mesh nets, spearfishing without SCUBA gear, and hand netting. Coral-destroying techniques, such as dynamite, cyanide, and trawling, are prohibited. By protecting the reef, villagers are guarding the nursery of an entire marine ecosystem. Young fish growing up in the shelter of the coral disperse to neighboring waters and yield abundant harvests. Fishermen report that they spend much less time traveling to distant fishing areas now that fish around the island are so much more abundant.
1-4 4

5. 1.1 Understanding Our Environment
In this chapter you will learn about many serious environmental problems such as overfishing.
You will also read about promising, exciting solutions to many of these problems.
In this chapter we examine some of the serious challenges in environmental science and some promising signs of progress. We also explore the nature of science. What makes the scientific method different from other forms of inquiry? Why do scientists like to answer questions with numbers? Finally we review some of the fundamental ideas that have shaped the ways we think about the environment and our place in it.
1-5 5

6. What is Environmental Science?
Environmental science is the systematic study of our environment and our place in it.
As shown in Fig. 1.2, environmental science draws on many fields of knowledge to fully understand a problem and solve it.
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.
1-6 6

7. Environmental Science is a Global Subject
There are many interdependencies between global and regional environmental systems.
Often the best way to learn environmental science is to study it in the context of real places.
Often the best way to learn environmental science is to see how principles play out in real places. Familiarity with the world around us will help you understand the problems and their context. Throughout this book we’ve provided links to places you can see in Google Earth, a free online mapping program that you can download from googleearth.com. When you see a blue globe in the margin of this text, like the one at left, you can go to Connect and find place marks that let you virtually visit places discussed. In Google Earth you can also save your own placemarks and share them with your class.
09/22/10
1-7

8. We Inhabit a Remarkable Planet
We live in an incredibly prolific and colorful world that is unique in the universe.
Temperatures here are mild and relatively constant.
Plentiful supplies of clean air, fresh water, and fertile soil are regenerated by biogeochemical cycles and biological communities.
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 constantly regenerated by biological communities.
1-8 8

9. Our Planet Has an Amazingly Rich Diversity of Life
Millions of beautiful and intriguing species populate the earth and help sustain a habitable environment.
This vast multitude of life creates complex, interrelated communities.
Perhaps the most amazing feature of our planet is its rich diversity of life. This vast multitude of life creates complex, interrelated communities where towering trees and huge animals live together with, and depend upon, such tiny life-forms as viruses, bacteria, and fungi. Together, all these organisms make up delightfully diverse, self-sustaining ecosystems, including dense, moist forests; vast, sunny savannas; and richly colorful coral reefs.
1-9 9

10. 1.2 Crises and Opportunities
With over 7 billion people on Earth, we are adding about 80 million more each year.
Present trends project a world population between 8 and 10 billion by 2050.
The impact of that many people on our natural resources and ecological systems strongly influences many of the other problems we face.
There are over 7 billion people on earth, about twice as many as there were 40 years ago. We are adding about 80 million more each year. Although demographers report a transition to slower growth rates in most countries, with improved education and health care, present trends project a population between 8 and 10 billion by 2050 (fig. 1.5). The impact of that many people on our natural resources and ecological systems strongly influences many of the other problems we face.
1-10 10

11. Environmental and Political Challenges: Climate Change
Human activities have greatly increased concentrations of carbon dioxide and other “greenhouse” gases over the last 200 years.
Climate models indicate that by 2100, if current trends continue, global mean temperatures will probably warm between about 2 and 6 ˚ C.
The atmosphere normally captures heat near the earth’s surface, which is why it is warmer here than in space, but human activities such as burning fossil fuels, clearing forests and farmlands, and raising ruminant animals have greatly increased concentrations of carbon dioxide and other “greenhouse gases.” In the past 200 years, atmospheric CO2 concentrations have increased about 30 percent. Climate models indicate that by 2100, if current trends continue, global mean temperatures will probably increase by 2° to 6°C compared to 1990 temperatures (3.6° and 12.8°F: fig. 1.6a), far warmer than the earth has been since the beginning of human civilization.
1-11 11

12. Environmental and Political Problems: Hunger
Over the past century, global food production has increased faster than human population growth, but hunger remains a chronic problem.
At least 60 million people face acute food shortages due to weather, politics, or war.
Over the past century, global food production has increased faster than human population growth, but hunger remains a chronic problem because food resources are unevenly distributed. At the same time, soil scientists report that about two-thirds of all agricultural lands show signs of degradation. The biotechnology and intensive farming techniques responsible for much of our recent production gains are too expensive for many poor farmers. Can we find ways to produce the food we need without further environmental degradation and can we distribute food more equitably? In a world of food surpluses, currently more than 850 million people are chronically undernourished and at least 60 million people face acute food shortages due to weather, politics, or war (fig. 1.6b).
1-12

13. Environmental and Political Problems: Clean Water
1.1 billion people lack access to safe drinking water.
Every year polluted water contributes to the death of more than 15 million people.
40 percent of the population live in countries where water demands now exceed supplies.
Water may be the most critical resource in the twenty-first century. Already at least 1.1 billion people lack access to safe drinking water and twice that many don’t have adequate sanitation. Polluted water contributes to the death of more than 15 million people every year, most of them children under age 5. About 40 percent of the world population lives in countries where water demands now exceed supplies, and the UN projects that by 2025 as many as three-fourths of us could live under similar conditions (fig. 1.6c).
1-13 13

14. Environmental and Political Problems: 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, and there are many problems associated with their acquisition and use.
Investing in renewable energy and energy conservation measures could give us cleaner, less destructive options.
How we obtain and use energy will greatly affect our environmental future. 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 the costs of extracting and using these fuels are high in terms of air and water pollution, mining damage, political conflicts, and of course climate change. Energy conservation and cleaner, renewable energy resources—solar, wind, geothermal, and biomass power—could give us cleaner, less destructive options if we decide to invest in them.
1-14 14

15. Environmental and Political Problems: Air Quality
Air quality has worsened dramatically in many areas, especially China and India.
Nobel laureate Paul Crutzen estimates that at least 3 million people die each year from diseases triggered by air pollution.
Worldwide, the United Nations estimates that more than 2 billion metric tons of air pollutants (not including carbon dioxide or wind-blown soil) are released each year.
Air quality has worsened dramatically in newly industrializing areas, including much of China and India. An “Asian brown cloud,” a 3-km (2-mile)-thick toxic haze of ash, acids, aerosols, dust, and photochemical smog, regularly covers the entire Indian subcontinent for much of the year. Nobel laureate Paul Crutzen estimates that at least 3 million people die each year from diseases triggered by air pollution. Worldwide, the United Nations estimates, more than 2 billion metric tons of air pollutants (not including carbon dioxide or wind-blown soil) are released each year. These air pollutants travel easily around the globe. On some days 75 percent of the smog and airborne particulates in California originate in Asia; mercury, polychlorinated biphenyls (PCBs), and other industrial pollutants accumulate in arctic ecosystems and in the tissues of native peoples in the far north.
1-15 15

16. Environmental and Political Problems: Biodiversity Loss
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.
Biologists report that habitat destruction, overexploitation, pollution, and the introduction of exotic organisms are eliminating species as quickly as the great extinction that marked the end of the age of dinosaurs. The UN Environment Programme reports that over the past century more than 800 species have disappeared, and at least 10,000 species are now considered threatened. This includes about half of all primates and freshwater fish, together with around 10 percent of all plant species. Top predators, including nearly all the big cats in the world, are particularly rare and endangered. A nationwide survey of the United Kingdom in 2004 found that most bird and butterfly populations had declined by 50 to 75 percent over the previous 20 years. At least half of the forests existing before the introduction of agriculture have been cleared, and many of the ancient forests, which harbor some of the greatest biodiversity, are rapidly being cut for timber, for oil extraction, or for agricultural production of globally traded commodities such as palm oil or soybeans.
1-16 16

17. Environmental and Political Problems: Marine Resources
More than a billion people depend on seafood for their main source of animal protein.
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.
As noted in the opening case study, the ocean is an irreplaceable food resource. 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. 1.6d). 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.
1-17 17

18. Signs of Progress: Population and Pollution
Pollution has been decreased and the population has stabilized in most industrialized countries and even in some very poor countries where democracy has been established.
Since 1960, the average number of children born per woman worldwide has decreased from 5.0 to
The UN Population Division predicts that the world population will stabilize at about 8.9 billion by the year 2050.
Many cities in Europe and North America are cleaner and much more livable now than they were a century ago, and as a consequence health and longevity have improved sharply. Population has stabilized in most industrialized countries and even in some very poor countries where social security, education, and democracy have been established. Since 1960 the average number of children born per woman worldwide has decreased from 5 to 2.45 (see fig. 1.5). By 2050, the UN Population Division predicts, most countries will have fertility rates below the replacement rate of 2.1 children per woman. If this happens, the world population will stabilize at about 8.9 billion rather than the 9.3 billion previously expected.
1-18

19. Signs of Progress: Health
The incidence of life- threatening infectious diseases like smallpox and polio have been reduced sharply in most countries during the past century, while life expectancies have nearly doubled.
The incidence of life-threatening infectious diseases has been reduced sharply in most countries during the past century, while life expectancies have nearly doubled, on average (fig. 1.7a). Smallpox has been completely eradicated and polio has been vanquished except in a few countries. Since 1990 more than 800 million people have gained access to improved water supplies and modern sanitation. In spite of population growth that added nearly a billion people to the world during the 1990s, the number of people facing food insecurity and chronic hunger during this period actually declined by about 40 million.
1-19

20. Signs of Progress: Renewable Energy
Encouraging progress is being made in a transition to renewable energy sources.
Growth in wind energy, solar, and biomass power and improvements in efficiency are beginning to reduce reliance on fossil fuels.
The cost of solar power has plummeted, and both solar and wind power are now far cheaper, easier, and faster to install than nuclear power or new coal plants.
There has been dramatic and surprising progress in the transition to renewable energy sources. Growth in wind energy, solar, and biomass power and improvements in efficiency are beginning to reduce reliance on fossil fuels. The cost of solar power has plummeted, and in many areas solar costs the same as conventional electricity over time. Solar and wind power are now far cheaper, easier, and faster to install than nuclear power or new coal plants.
1-20

21. Signs of Progress: Information and Education
Literacy and access to education are expanding in most regions of the world.
The Internet makes it easier to share environmental solutions.
Expanding education for girls is driving declining birth rates worldwide.
Because so many environmental issues can be fixed by new ideas, technologies, and strategies, expanding access to knowledge is essential to progress. The increased speed at which information now moves around the world offers unprecedented opportunities for sharing ideas. At the same time, literacy and access to education are expanding in most regions of the world (fig. 1.7b). Rapid exchange of information on the Internet also makes it easier to quickly raise global awareness of environmental problems, such as deforestation or pollution, that historically would have proceeded unobserved and unhindered. Expanding education for girls is a primary driver for declining birth rates worldwide.
09/22/10
1-21

22. Signs of Progress: Conservation of Forests and Nature Preserves
Deforestation has slowed in Asia.
A former leader in deforestation, Brazil, is now working to protect forests.
13.5 percent
of the world’s land area is now in protected areas.
The rate of deforestation has slowed in Asia, from over 8 percent during the 1980s to less than 1 percent in the 1990s. Brazil, which has led global deforestation rates for decades, is working to protect forests. Nature preserves and protected areas have increased dramatically over the past few decades. In 2010 there were more than 100,000 parks and nature preserves in the world, representing more than 20 million km2 (about 7.7 million mi2), or about 13.5 percent of the world’s land area (fig. 1.7d). Ecoregion and habitat protection remains uneven, and some areas are protected only on paper. Still, this is dramatic progress in biodiversity protection.
1-22 22

23. Signs of Progress: Protection of Marine Resources
Marine protected areas and better monitoring of provides for more sustainable management.
Marine reserves have been established in California, Hawaii, New Zealand, Great Britain, and many other areas.
Although marine resources continue to be badly overexploited, countries are gradually beginning to acknowledge the problem and find solutions. Marine protected areas and improved monitoring of fisheries provide opportunities for sustainable management (fig. 1.7c). The strategy of protecting fish nurseries is an altogether new approach to sustaining ocean systems and the people who depend on them. Marine reserves have been established in California, Hawaii, New Zealand, Great Britain, and many other areas.
1-23 23

24. 1.3 Human Dimensions of Environmental Science
Aldo Leopold, one of the greatest thinkers on conservation, observed that the great challenges in conservation have less to do with managing resources than with managing people and our demands on resources.
In this section we’ll review some key ideas that guide our understanding of human dimensions of environmental science and resource use.
Aldo Leopold, one of the greatest thinkers on conservation, observed that the great challenges in conservation have less to do with managing resources than with managing people and our demands on resources. Foresters have learned much about how to grow trees, but still we struggle to establish conditions under which villagers in developing countries can manage plantations for themselves. Engineers know how to control pollution but not how to persuade factories to install the necessary equipment. City planners know how to design urban areas, but not how to make them affordable for everyone. In this section we’ll review some key ideas that guide our understanding of human dimensions of environmental science and resource use. These ideas will be useful throughout the rest of this book.
1-24 24

25. How Do We Describe Resource Use and Conservation?
When we consider resource consumption, an important idea is throughput, the amount of resources we use and dispose of.
Ecosystem services refers to the services or resources provided by environmental systems. Usually we rely on these resources without thinking about them.
The tragedy of the commons refers to how population growth inevitably leads to the overuse and destruction of common resources.
The natural world supplies the water, food, metals, energy, and other resources we use. Some of these resources are finite; some are constantly renewed. When we consider resource consumption, an important idea is throughput, the amount of resources we use and dispose of.
Ecosystem services, another key idea, refers to services or resources provided by environmental systems (fig. 1.8). Provisioning of resources, such as the fuels we burn, may be the most obvious service we require. Supporting services are less obvious until you start listing them: these include water purification, production of food and atmospheric oxygen by plants, or decomposition of waste by fungi and bacteria. Regulating services include maintenance of temperatures suitable for life by the earth’s atmosphere, or carbon capture by green plants, which maintains a stable atmospheric composition. Cultural services include a diverse range of recreation, aesthetic, and other nonmaterial benefits.
Are there enough resources for all of us? One of the answers to this basic question was given in an essay entitled “Tragedy of the Commons,” published in 1968 in the journal Science by ecologist Garret Hardin. In this classic framing of the problem, Hardin argues that population growth leads inevitably to overuse and then
destruction of common resources—such as shared pastures, unregulated fisheries, fresh water, land, and clean air. This classic essay has challenged many to explore alternative ideas about resource management.
09/22/10
1-25

26. Ecosystem Services
09/22/10
1-26

27. Sustainability Means Environmental and Social Progress
Sustainability is a search for long term ecological stability and human progress.
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.”
Sustainability is a search for ecological stability and human progress that can last over the long term. 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.
09/22/10
1-27

28. Fighting Poverty Helps Protect Our Shared Environment
Policy makers now recognize that eliminating poverty and protecting our common environment are inextricably interlinked.
Impoverished peoples are both the victims and the agents of environmental degradation.
Policy makers now recognize that eliminating poverty and protecting our common environment are inextricably interlinked. The world’s poorest people are both the victims and the agents of environmental degradation (fig. 1.9). The poorest people are often forced to meet short-term survival needs at the cost of long-term sustainability. Desperate for croplands to feed themselves and their families, many move into virgin forests or cultivate steep, erosion-prone hillsides, where soils are depleted after only a few years. Others migrate to the grimy, crowded slums and ramshackle shantytowns that now surround most major cities in the developing world. With no way to dispose of wastes, the residents have no choice but to foul their environment further and washing and drinking. Children raised in poverty and illness, with few economic opportunities, often are condemned to perpetuate a cycle of poverty.
09/22/10
1-28

29. Affluence is a Goal and a Liability
The U.S. with less than 5 percent of the world’s total population, consumes about 1/4 of most commercially traded commodities, such as oil, and produces a ¼ to ½ of most industrial wastes, such as greenhouse gases, pesticides, and other persistent pollutants.
As the rest of the world seeks to achieve a similar standard of living, with higher consumption of conveniences and consumer goods, what will the effects be on the planet?
The United States with less than 5 percent of the world’s 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 lb) of raw materials, including 18 kg (40 lb) of fossil fuels, 13 kg (29 lb) of other minerals, 12 kg (26 lb) of farm products, 10 kg (22 lb) 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. As the rest of the world seeks to achieve a similar standard of living, with higher consumption of conveniences and consumer goods, what will the effects be on the planet? What should we do about this? Can we reduce our consumption rates? Can we find alternative methods to maintain conveniences and a consumption-based economy with lower environmental costs? These are critical questions as we seek to ensure a reasonable future for our grandchildren.
1-29 29

30. The Cost of Affluence
“And may we continue to be worthy to consume a disproportionate share of the planet’s resources.”
1-30

31. What is the State of Poverty and Wealth Today?
Countries with the highest per capita income, more than $40,000 (U.S.) per year, make up only 10 % of the world’s population. These countries are all in Europe or North America plus Japan, Singapore, Australia, and the United Arab Emirates.
More than 70% of the world’s population—some 5 billion people—live in countries where the average per capita income is less than $5,000, roughly one-tenth of the U.S. average. These countries include China and India.
Wealth is also unevenly divided at the global scale. The world’s richest 200 people have a combined wealth greater than that of the 3.5 billion people who make up the poorest half of the world’s population. Countries with the highest per capita income, more than $40,000 (U.S.) per year, make up only 10 percent of the world’s population. These countries are all in Europe or North America (the average U.S. income in 2010 was about $48,000), plus Japan, Singapore, Australia, and the United Arab Emirates (fig. 1.11). More than 70 percent of the world’s population—some 5 billion people—live in countries where the average per capita income is less than $5,000, roughly one-tenth of the U.S. average. These countries include China and India, the world’s most populous countries, with a combined population of over 2.5 billion people. Of the 50 poorest countries, where income is less than $2.50 per day, 33 are
in sub-Saharan Africa.
1-31

32. Per Capital Income in Different Regions (in U.S. Dollars)
Per capita income in different regions (in 2010 U.S. dollars). Overall income has climbed, but the gap between rich and poor countries has grown faster.
09/22/10
1-32

33. Indigenous Peoples Safeguard Biodiversity
The 500 million indigenous people who remain in traditional homelands still possess valuable ecological wisdom and remain the guardians of little-disturbed habitats that are refuges for rare and endangered species and undamaged ecosystems.
In both rich and poor countries, native or indigenous peoples are generally the least powerful, most neglected groups. 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. Of the world’s nearly 6,000 recognized cultures, 5,000 are indigenous; and these account for only about 10 percent of the total world population. At least half of the world’s 6,000 distinct languages are dying because they are no longer taught to children. When the last elders who still speak the language die, so will the culture that was its origin. Lost with those cultures will be a rich repertoire of knowledge about nature and a keen understanding of a particular environment and way of life (fig. 1.12).
Nonetheless, the 500 million indigenous people who remain in traditional homelands still possess valuable ecological wisdom and remain the guardians of little-disturbed habitats that are refuges for rare and endangered species and undamaged ecosystems. 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. Recognizing native land rights and promoting political pluralism can be among the best ways to safeguard ecological processes and endangered species. For this reason, a few countries, such as Papua New Guinea, Fiji, Ecuador, Canada, and Australia, acknowledge indigenous title to extensive land areas.
1-33 33

34. 1.4 Science Helps Us Understand Our Environment
What is science?
Science is a process for producing knowledge based on observations.
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 rests on the assumption that the world is knowable and that we can learn about it by careful observation and logical reasoning.
What is science? Science (from scire, “to know” in Latin) is a process for producing knowledge based on observations (fig. 1.13). 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). The benefit of scientific thinking is that it searches for testable evidence. As evidence improves, we can seek better answers to important questions.
1-34 34

35. Basic Principles of Science
09/22/10
1-35

36. Science Depends on Skepticism and Reproducibility
Ideally, scientists are skeptical. They are cautious about accepting proposed explanations until there is substantial evidence to support it.
Scientists aim to be methodical and unbiased.
Scientists demand reproducibility. Making an observation or obtaining a result just once doesn’t count for much. You have to produce the same result consistently to be sure that your first outcome wasn’t a fluke.
Ideally scientists are skeptical. They are cautious about accepting a proposed explanation until there is substantial evidence to support it. Even then, every explanation is considered only provisionally true, because there is always a possibility that some additional evidence may appear to disprove it. Scientists also aim to be methodical and unbiased. 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. 1.14). The peer review process is an essential part of ensuring that scientists maintain good standards in study design, data collection, and interpretation of results.
Scientists demand reproducibility because they are cautious about accepting conclusions. Making an observation or obtaining a result just once doesn’t count for much. You have to produce the same result consistently to be sure that your first outcome wasn’t a fluke. Even more important, you must be able to describe the conditions of your study so that someone else can reproduce your findings. Repeating studies or tests is known as replication.
1-36 36

37. We Use Both Deductive and Inductive Reasoning
Ideally scientists deduce conclusions from general laws that they know to be true.
This logical reasoning from general to specific is known as deductive reasoning.
Conversely, reasoning from many observations to produce a general rule is inductive reasoning.
Ideally scientists deduce conclusions from general laws that they know to be true. This logical reasoning from general to specific is known as deductive reasoning.
Often, however, we do not know general laws that guide natural systems. Then we must rely on observations to find general rules. Reasoning from many observations to produce a general rule is inductive reasoning. 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 absolute laws.
1-37 37

38. The Scientific Method is an Orderly Way to Examine Problems
1. Make an observation and identify a question: Your flashlight doesn’t light and you think to yourself: “what might be wrong?”
2. Propose a hypothesis: “The flashlight doesn’t work because the batteries are dead.”
3. Test your hypothesis: “If I replace the batteries then the flashlight should work.”
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.
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.
1-38 38

39. The Scientific Method
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. 1.14). The peer review process is an essential part of ensuring that scientists maintain good standards in study design, data collection, and interpretation of results.
1-39 39

40. Understanding Probability Reduces Uncertainty
Probability is a measure of how likely something is to occur.
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, an 80 percent chance, that you won’t catch a cold.
One strategy to improve confidence in the face of uncertainty is to focus on probability. Probability is a measure of how likely something is to occur. 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.
Probability is often a more useful idea than proof. This is because absolute proof is hard to achieve, but we can frequently demonstrate a strong trend or relationship, one that is unlikely to be achieved by chance. For example, suppose you flipped a coin and got heads 20 times in a row. That could happen by chance, but it would be pretty unlikely. You might consider it very likely that there was a causal explanation, such as that the coin was weighted toward heads. Often we consider a causal explanation reliable (or “significant”) if there is less than 5 percent probability that it happened by random chance (see Exploring Science, p. 17).
1-40 40

41. Experimental Design Can
Reduce Bias
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 or controlled.
Blind experiments are those 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 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.
A natural experiment is when you observe natural events and interpret a causal relationship between the variables. It involves observation of events that have already happened. Many scientists depend on natural experiments: A geologist, for instance, might want to study mountain building, or an ecologist might want to learn about how species coevolve, but neither scientist can spend millions of years watching the process happen. Similarly, a toxicologist cannot give people a disease just to see how lethal it is.
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.
1-41 41

42. Science is a Cumulative Process
Good science is rarely carried out by a single individual working in isolation. Instead, a community of scientists collaborates in a cumulative, self- correcting process.
The idea of consensus is important in science.
Sometimes new ideas emerge that cause major shifts in scientific consensus. These great changes in explanatory frameworks ware called paradigm shifts.
Good science is rarely carried out by a single individual working in isolation. Instead, a community of scientists collaborates in a cumulative, self-correcting process. You often hear about big breakthroughs and dramatic discoveries that change our understanding overnight, but in reality these changes are usually the culmination of the labor of many people, each working on different aspects of a common problem, each adding small insights to solve a problem.
Ideas and information are exchanged, debated, tested, and retested to arrive at scientific consensus, or general agreement among informed scholars. The idea of consensus is important. For those not deeply involved in a subject, the multitude of contradictory results can be bewildering: Are coral reefs declining, and does it matter? Is climate changing, and how much? Among those who have done many studies and read many reports, there tends to emerge a general agreement about the state of a problem. Scientific consensus now holds that many coral reefs are in danger, as a result of pollution, physical damage, and warming seas. Consensus is that global climate conditions are changing, though models differ somewhat on how rapidly they will change in different regions.
Sometimes new ideas emerge that cause major shifts in scientific consensus. These great changes in explanatory frameworks were termed paradigm shifts by Thomas Kuhn (1967), who studied revolutions in scientific thought. According to Kuhn, paradigm shifts occur when a majority of scientists accept that the old explanation no longer describes new observations very well.
1-42 42

43. What is Sound Science?
When controversy surrounds science, claims about sound science and accusations of “junk” science often arise.
What do these terms mean, and how can you evaluate who is right?
When controversy surrounds science, claims about sound science and accusations of “junk” science often arise. What do these terms mean, and how can you evaluate who is right? When you hear arguments about whose science is valid, you need to remember the basic principles of science: Are the disputed studies reproducible? Are conclusions drawn with caution and skepticism? Are samples large and random? Are conclusions supported by a majority of scholars who have studied the problem? Do any of the experts have an economic interest in the outcome?
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.
1-43 43

44. 09/22/10

45. Critical Thinking
An ability to think critically, clearly, and analytically about a problem may be the most valuable skill you can learn.
Critical thinking is a term we use to describe logical, orderly, analytical assessment of ideas, evidence, and arguments.
If you ask "How do I know that what I just said is true?" then you are practicing critical thinking.
In science we frequently ask, “How do I know that what you just said is true?” Part of the way we evaluate arguments in science has to do with observable evidence, or data. Logical reasoning from evidence is also essential. And part of the answer lies in critical evaluation of evidence. An ability to think critically, clearly, and analytically about a problem may be the most valuable skill you can learn in any of your classes. As you know by now, many issues in environmental science are hotly disputed, with firm opinions and plenty of evidence on both sides. How do you evaluate contradictory evidence and viewpoints?
Critical thinking is a term we use to describe logical, orderly, analytical assessment of ideas, evidence, and arguments. Developing this skill is essential for the course you are taking now. Critical thinking is also an extremely important skill for your life in general.
1-45

46. 1-46

47. Critical Thinking Helps us Analyze Information
There are many different aspects of critical thinking:
Analytical thinking helps you break a problem down into its constituent parts.
Creative thinking asks, “How might I approach this problem in new and inventive ways?”
Logical thinking evaluates whether the structure of your argument make sense.
Reflective thinking asks, “What does it all mean?”
There are many different aspects of critical thinking. Much of the process is about carefully examining what you are trying to accomplish, and how you will know when you have the answer. Critical thinking also involves examining the source of information and how much that source influences the kind of information you receive. Analytical thinking helps you break a problem down into its constituent parts. Creative thinking asks, “How might I approach this problem in new and inventive ways?” Logical thinking evaluates whether the structure of your argument make sense. Reflective thinking asks, “What does it all mean?”
09/22/10
1-47

48. Critical Thinking Helps You Learn Environmental Science
In this course you will have many opportunities to practice critical thinking.
When reading your textbook, hearing the news, or watching television, try to distinguish between statements of fact and opinion.
Watch for cases in which you need to think for yourself, and use your critical and reflective thinking skills to uncover the truth.
When reading this text, hearing the news, or watching television, try to distinguish between statements of fact and opinion. Ask yourself if the premises support the conclusions drawn from them. Although most of us try to be fair and even-handed in presenting controversies, our personal biases and values—some of which we may not even recognize—affect how we see issues and present arguments. Watch for cases in which you need to think for yourself, and use your critical and reflective thinking skills to uncover the truth.
1-48

49. 1.6 Where Do Our Ideas About The Environment Come From?
Many of our current views on the environment are rooted in the writings of relatively recent environmental thinkers.
Their work can be grouped into 4 stages:
Resource conservation for optimal use
Nature preservation for moral and aesthetic reasons
Concern over health and ecological consequences of pollution
Global environmental citizenship
These stages are not mutually exclusive.
Many of our current responses to these changes are rooted in the writings of relatively recent environmental thinkers. For simplicity, their work can be grouped into about four distinct stages: (1) resource conservation for optimal use; (2) nature preservation for moral and aesthetic reasons; (3) concern over health and ecological consequences of pollution; (4) global environmental citizenship. These stages are not mutually exclusive. You might embrace them all simultaneously. As you read this section, consider why you agree with those you find most appealing.
1-49 49

50. Nature Protection Has Historic Roots
Human misuse of nature is not unique to modern times.
Plato complained of environmental degradation in ancient Greece in 4 B.C.
Eighteenth-century French and British colonial administrators observed and understood the connections between deforestation, soil erosion, and local climate change.
Recognizing human misuse of nature is not unique to modern times. Plato complained in the fourth century B.C. that Greece once was blessed with fertile soil and clothed with abundant forests of fine trees. After the trees were cut to build houses and ships, however, heavy rains washed the soil into the sea, leaving only a rocky “skeleton of a body wasted by disease.” Springs and rivers dried up, and farming became all but impossible. Despite these early observations, most modern environmental ideas developed in response to resource depletion associated with more
recent agricultural and industrial revolutions.
1-50

51. Resource Waste Triggered Pragmatic Resource Conservation
Many historians consider the publication of Man and Nature in 1864 by George Perkins Marsh as the beginning of environmental protection in North America.
He warned of the ecological consequences to the waste and destruction of resources.
Largely because of his book, national forest reserves were established in the U.S. in 1873 to protect dwindling timber supplies and endangered watersheds.
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.
1-51 51

52. Roosevelt & Pinchot Begin Pragmatic Utilitarian Conservation
U.S. President Theodore Roosevelt and his chief conservation adviser, Gifford Pinchot, argued that the forests should be saved to provide homes and jobs for future generations.
Pinchot, was the first chief of the Forest Service. He put resource management on a rational and scientific basis for the first time in American history and helped John Muir and Roosevelt to establish the national forest, park, and wildlife refuge systems.
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.” “There has been a fundamental misconception,” Pinchot wrote, “that conservation means nothing but husbanding of resources for future generations. Nothing could be further from the truth. The first principle of conservation is development and use of the natural resources now existing on this continent for the benefit of the people who live here now. There may be just as much waste in neglecting the development and use of certain natural resources as there is in their destruction.” This pragmatic approach still can be seen in the multiple-use policies of the U.S. Forest Service.
1-52 52

53. Utilitarian Conservationists
President Theodore Roosevelt
Conservation Advisor Gifford Pinchot
1-53

54. Ethical and Aesthetic Concerns Inspired the Preservation Movement
John Muir, the first president of the Sierra Club, opposed Pinchot’s utilitarian policies.
He argued that nature deserves to exist for its own sake.
Aesthetic and spiritual values formed the core of his philosophy.
John Muir (fig. 1.18c), 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. Aesthetic and spiritual values formed the core of his philosophy of nature protection. This outlook prioritizes preservation because it emphasizes the fundamental right of other organisms—and nature as a whole—to exist and to pursue their own interests. Muir wrote, “The world, we are told, was made for man. A presumption that is totally unsupported by the facts Nature’s object in making animals and plants might possibly be first of all the happiness of each one of them Why ought man to value himself as more than an infinitely small unit of the one great unit of creation?”
1-54 54

55. Wildlife Ecologist Aldo Leopold
Formulated and advocated for a land ethic.
Aldo Leopold planted trees in a practical experiment aimed at restoring the health and beauty of the land.
He wrote a collection of environmental essays espousing a respect for the land and he also founded the Wilderness Society.
In 1935, pioneering wildlife ecologist Aldo Leopold (fig. 1.18d) bought a small, worn- out farm in central Wisconsin. A dilapidated chicken shack, the only remaining building, was remodeled into a rustic cabin. Working together with his children, Leopold planted thousands of trees in a practical experiment in restoring the health and beauty of the land. “Conservation,” he wrote, “is the positive exercise of skill and insight, not merely a negative exercise of abstinence or caution.” The shack became a writing refuge and became the main focus of A Sand County Almanac, a much beloved collection of essays about our relation with nature. In it, Leopold wrote, “We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong, we may begin to use it with love and respect.” Together with Bob Marshall and two others, Leopold was a founder of the Wilderness Society.
1-55 55

56. Rising Pollution Levels Led to the Modern Environmental Movement
Poor air quality, due to the burning of coal in London, became an increasing problem, eventually resulting in the deaths of 12,000 people in the year 1952.
In response to pollution from the chemical industries after World War II, Rachel Carson published a book, Silent Spring, in 1962.
This book awakened the public to the threats of toxic chemicals to humans as well as other species and launched the modern environmental movement.
1-56

57. Author Rachel Carson
1-57

58. Environmental Pioneers David Brower and Barry Commoner
Activist David Brower introduced many of the techniques of environmental lobbying and activism in use today.
Molecular Biologist Barry Commoner has been a leader in analyzing the links between science, technology, and society.
Both activism and research remain hallmarks of the modern environmental movement.
1-58

59. Environmental Pioneers
David Brower
Barry Commoner
1-59

60. Environmental Quality is Tied
to Social Progress
Increasingly, environmental activists are making explicit the links between environmental quality and social progress on a global scale.
Today’s environmental movement is pushing sustainable development, the idea that economic improvement for the world’s poorest populations is possible without devastating the environment.
Dr. Wangari Maathai is a notable example who has supported sustainable development in Kenya, where she founded the Green Belt Movement.
Increasingly, environmental activists are making explicit the links between environmental quality and social progress on a global scale. The idea of sustainable development, an idea that has run through this chapter and is a core concept of modern environmental thought, is that economic improvement for the world’s poorest populations is possible without devastating the environment.
Some of today’s leading environmental thinkers come from developing nations, where poverty and environmental degradation together plague hundreds of millions of people. Dr. Wangari Maathai of Kenya (1940–2011) was a notable example. In 1977, Dr. Maathai founded the Green Belt Movement in her native Kenya as a way to both organize poor rural women and restore their environment. Beginning at a small, local scale, this organization has grown to more than 600 grassroots networks. across Kenya. They have planted more than 30 million trees while mobilizing communities for self-determination, justice, equity, poverty reduction, and environmental conservation. Dr. Maathai was elected to the Kenyan Parliament and served as Assistant Minister for Environment and Natural Resources. Her leadership has helped bring democracy and good government to her country. In 2004 she received the Nobel Peace Prize for her work,
1-60 60

61. Dr. Wangari Maathai
Some of today’s leading environmental thinkers come from developing nations, where poverty and environmental degradation together plague hundreds of millions of people. Dr. Wangari Maathai of Kenya (1940–2011) was a notable example. In 1977, Dr. Maathai founded the Green Belt Movement in her native Kenya as a way to both organize poor rural women and restore their environment. Beginning at a small, local scale, this organization has grown to more than 600 grassroots networks. across Kenya. They have planted more than 30 million trees while mobilizing communities for self-determination, justice, equity, poverty reduction, and environmental conservation. Dr. Maathai was elected to the Kenyan Parliament and served as Assistant Minister for Environment and Natural Resources. Her leadership has helped bring democracy and good government to her country. In 2004 she received the Nobel Peace Prize for her work.
1-61

62. Conclusion
Environmental science gives us useful tools and ideas for understanding both environmental problems and new solutions to those problems.
We face many persistent environmental problems, but we can also see many encouraging examples of progress.
Resolving these multiple problems together is the challenge for sustainability.
Science gives us an orderly, methodical approach to examining environmental problems.
1-62

63. Practice Quiz
1. Describe why fishing has changed at Apo Island and the direct and indirect effects on people’s lives.
2. What is the idea of ecological services? Give an example.
3. Distinguish between a hypothesis and a theory.
4. Describe the steps in the scientific method.
5. What is probability? Give an example.
6. Why are scientists generally skeptical? Why do tests require replication?
7. What is the first step in critical thinking, according to table 1.4?
1-63

64. Practice Quiz (continued)
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 1.6a does the most dramatic warming occur?
1-64

65. Practice Quiz (continued)
11. Describe some signs of progress in overcoming global environmental problems.
12. What is the link between poverty and environmental quality?
13. Define or describe sustainability and sustainable development.
09/22/10
1-65