Solutions Manual for Essential Environment 7th Edition by Withgott

1 Science and Sustainability: An Introduction to Environmental Science Chapter Objectives This chapter will help students: 1.1 Describe the field of environmental science 1.2 Explain the importance of natural resources and ecosystem services to our lives 1.3 Discuss population growth, resource consumption, and their consequences 1.4 Explain what is meant by an ecological footprint 1.5 Describe the scientific method and the process of science 1.6 Apply critical thinking skills to assess the reliability of information 1.7 Recognize the role of ethics in environmental science, and compare major ethical approaches 1.8 Appreciate the importance of environmental justice 1.9 Identify major pressures on the global environment 1.10 Discuss the concept of sustainability, and describe sustainable solutions being pursued on campuses and in the wider world

Lecture Outline I.

Our Island, Earth A. Our environment surrounds us.

1. Our environment consists of all the living and nonliving things around us.

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2. The fundamental insight of environmental science is that we are part of the “natural” world and that our interactions with the rest of it matter a great deal.

B. Environmental science explores our interactions with the world.

1. Understanding our relationship with the world around us is vital because we depend on our environment for air, water, food, shelter, and everything else essential for living.

2. Environmental science is the scientific study of how the natural world works, how our environment affects us, and how we affect our environment.

3. Environmental scientists study the issues most centrally important to our world and its future.

C. We rely on natural resources.

1. Natural resources are the substances and energy sources we take from our environment and that we rely on to survive.

2. Renewable natural resources are replenished over short periods.

Nonrenewable natural resources, such as minerals and fossil fuels, are in finite supply and are formed far more slowly than we use them.

D. We rely on ecosystem services.

1. Earth’s natural systems provide services on which we depend. Such essential services are called ecosystem services.

2. Just as we may deplete natural resources, we may degrade ecosystem services when, for example, we destroy habitat or generate pollution.

E. Population growth amplifies our impact.

1. Today, our population has grown beyond 8 billion people.

2. Two phenomena triggered our remarkable increase in population size. a) One was the agricultural revolution, which began about 10,000 years ago as people began to grow crops, domesticate animals, and live sedentary lives on farms and in villages; when they produced more food to meet their nutritional needs, they began having more children. b) The second, the industrial revolution, began in the mid-1700s and entailed a shift from rural life, animal-powered agriculture, and handcrafted goods toward an urban society provisioned by the mass production of factory-made goods and powered by fossil fuels.

F. Resource consumption exerts social and environmental pressures.

1. Our ecological footprint a) Mathis Wackernagel and William Rees developed the concept of the ecological footprint, which expresses the cumulative area of 2

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biologically productive land and water required to provide the resources a person or population consumes and to dispose of or recycle the waste the person or population produces. b) Wackernagel and his colleagues at the Global Footprint Network calculate that we are now using 71% more of our resources than are available on a sustainable basis. The practice of consuming more resources than are being replenished is termed overshoot because we are overshooting, or surpassing, Earth’s capacity to sustainably support us.

G. Conserving natural capital is like maintaining a bank account.

1. We can think of our planet’s vast store of resources and ecosystem services—Earth’s natural capital—as a bank account. To keep a bank account full, we need to leave the principal intact and spend only the interest, so that we can continue living off the account far into the future.

H. Environmental science can help us learn from the past.

1. Historical evidence suggests that civilizations can crumble when pressures from population and consumption overwhelm resource availability.

2. In today’s globalized society, the stakes are higher than ever because our environmental impacts are global. If we cannot forge sustainable solutions to our problems, then the resulting societal collapse will be global.

II.

The Nature of Environmental Science A. Environmental science is interdisciplinary.

1. Environmental science is interdisciplinary, bringing techniques, perspectives, and research results from multiple disciplines together into a broad synthesis.

2. Interdisciplinary fields are valuable because their practitioners consolidate and synthesize the specialized knowledge from many disciplines and make sense of it in a broad context to better serve the multifaceted interests of society.

3. Environmental science is especially broad because it encompasses not only the natural sciences but also the social sciences. Most environmental science programs focus more on the natural sciences, whereas programs that emphasize the social sciences often use the term environmental studies.

B. Environmental science is not the same as environmentalism.

1. Environmentalism is a social movement dedicated to protecting the natural world—and, by extension, people—from undesirable changes brought about by human actions.

III.

The Nature of Science

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1. Science is a systematic process for learning about the world and testing our understanding of it.

A. Scientists test ideas by critically examining evidence.

1. Scientists examine how the world works by making observations, taking measurements, and testing whether their ideas are supported by evidence.

2. A great deal of scientific work is descriptive science, research in which scientists gather basic information about organisms, materials, systems, or processes that are not yet well known.

3. If enough is known about a subject, scientists pursue hypothesis-driven science, research that proceeds in a more targeted and structured manner, using experiments to test hypotheses within a framework traditionally known as the scientific method.

B. The scientific method is a traditional approach to research.

1. The scientific method is a technique for testing ideas with observations.

2. The steps of the scientific method are: a) Make observations. Observations set the scientific method in motion and play a role throughout the process. b) Ask questions. Determining which questions to ask is one of the most important steps in the investigation process. c) Develop a hypothesis. A hypothesis is a statement that attempts to explain a phenomenon or answer a scientific question. d) Make predictions. A prediction is a specific statement that can be directly and unequivocally tested. e) Test the predictions. Scientists test predictions by gathering evidence that could potentially refute them and thus disprove the hypothesis.

The strongest form of evidence comes from experiments. An experiment is an activity designed to test the validity of a prediction or a hypothesis. It involves manipulating variables, or conditions that can change. i.

The independent variable is the variable that the scientist manipulates, while the dependent variable is the one that depends upon the first variable. Scientists conduct controlled experiments by controlling for the effects of all variables except the tested one. Often, controlled experiments have a treatment area that is manipulated and another that is not, called a control.

f) Analyze and interpret results. Scientists record data, or information, from their studies and analyze the data using statistical tests to see if the hypothesis is supported. If experiments disprove a hypothesis, the scientist will reject it and may formulate a new hypothesis to replace 4

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it. If experiments fail to reject a hypothesis, evidence in favor of it accumulates, and the researcher may eventually conclude that the hypothesis is well supported.

C. We test hypotheses in different ways.

1. A manipulative experiment is an experiment in which the researcher actively chooses and manipulates the independent variable. When we cannot, it is common for researchers to run natural experiments, which compare how dependent variables are expressed in naturally occurring, but different, contexts, and to search for correlation, or statistical association among variables.

2. Whenever possible, scientists try to integrate natural experiments and manipulative experiments to gain the advantages of each.

D. Scientists use graphs to represent data visually.

1. To summarize and present the data they obtain, scientists often use graphs. Graphs help to make patterns and trends in the data visually apparent and easy to understand.

E. The scientific process continues beyond the scientific method.

1. Peer review. Research results are submitted to a journal for publication.

Other scientists who specialize in the subject area are asked to provide comments and criticism and judge whether the work merits publication.

This process is known as peer review.

2. Grants and funding. To fund their research, most scientists need to spend a great deal of time requesting money from private foundations or from government agencies. Grant applications undergo peer review just as scientific papers do, and competition for funding is generally intense.

Scientists’ reliance on funding sources can occasionally lead to conflicts of interest.

3. Conference presentations. Scientists frequently present their work at professional conferences where they interact with colleagues and receive comments on their research.

4. Repeatability. The careful scientist may test a hypothesis repeatedly in various ways. Following publication, other scientists may attempt to reproduce the results in their own experiments.

5. Theories. If a hypothesis survives repeated testing by numerous research teams and continues to predict experimental outcomes and observations accurately, it may be incorporated into a theory. A theory is a widely accepted, well-tested explanation of one or more cause-andeffect relationships that has been extensively validated by a great amount of research.

F. Science undergoes paradigm shifts.

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1. A paradigm is a dominant view regarding a topic, based on the facts and experiments known at that time.

2. Paradigm shifts demonstrate the strength and vitality of science, showing science to be a process that refines and improves itself through time.

G. How can we judge the reliability of information?

1. One key criterion in evaluating the reliability of a source is to determine whether or not the information it offers is solidly based in evidence.

2. A person can get the most accurate understanding of a scientific question by reading the scientific literature directly.

3. Another way to learn about important scientific advances is to read articles by science writers published in media outlets that have built solid reputations over years or decades.

4. An original scientific research paper in a journal is an example of a primary source, a source that presents novel information and stands on its own. Articles or broadcasts produced by others about the contents of a primary source are examples of a secondary source.

H. We need science to help tackle our biggest challenges.

IV.

Environmental Ethics 1. Ethics is a branch of philosophy that involves the study of good and bad, right and wrong. Ethical standards are the criteria that differentiate right from wrong. Some ethicists are relativists, who believe that ethics do and should vary with social contexts. Others are universalists, who maintain that there exist objective notions of right and wrong that hold across cultures and contexts.

A. Environmental ethics pertains to people and the environment.

1. The application of ethical standards to relationships between people and nonhuman entities is known as environmental ethics.

2. Anthropocentrism describes a human-centered view of our relations with the environment.

3. Biocentrism ascribes inherent value to certain living things or to the biotic realm in general.

4. Ecocentrism judges actions in terms of their effects on whole ecological systems.

B. Conservation and preservation arose with the 20th century.

1. John Muir promoted the preservation ethic, which holds that we should protect the natural environment in a pristine, unaltered state.

2. Gifford Pinchot espoused the conservation ethic, which holds that people should put natural resources to use but that we have a responsibility to manage them wisely.

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C. Aldo Leopold’s land ethic inspires many people.

1. Aldo Leopold chose a more holistic perspective, maintaining that healthy ecological systems depend on protecting all of their interacting parts.

2. Leopold argued that people should view themselves and “the land” as members of the same community and that we are obligated to treat the land in an ethical manner.

3. Leopold intended the land ethic to help guide decision making.

D. Environmental justice seeks fair treatment for all people.

1. Environmental justice involves the fair and equitable treatment of all people, with respect to environmental policy and practice, regardless of their income level, race, ethnicity, gender, or sexual orientation.

V.

Sustainability and Our Future 1. Sustainability is a guiding principle of modern environmental science that means living within our planet’s means.

A. Population and consumption drive environmental impact.

1. Every day, we add over 200,000 people to the planet.

2. Our consumption of resources has risen even faster than our population.

3. The world’s people have not benefited equally from society’s overall rise in affluence.

4. Our growing population and consumption are intensifying many environmental impacts.

B. Energy choices will shape our future.

1. Our reliance on fossil fuels intensifies virtually every impact we exert on our environment.

2. However, in extracting coal, oil, and natural gas, we are splurging on a one-time bonanza, because these fuels are nonrenewable and in finite supply.

C. Sustainable solutions abound.

1. Humanity’s challenge is to develop solutions that enhance our quality of life while protecting and restoring the environment that supports us.

D. Students are promoting solutions on campus.

1. As a college student, you can help to design and implement sustainable solutions on your own campus. Proponents of campus sustainability seek ways to help colleges and universities reduce their ecological footprints.

E. Environmental science prepares you for the future.

VI.

Conclusion

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A. Finding effective ways of living peacefully, healthfully, and sustainably on our diverse and complex planet requires a solid ethical grounding as well as a sound scientific understanding of natural and social systems.

B. Science in general, and environmental science in particular, can help us develop balanced, workable, sustainable solutions and create a better world now and for the future.

Key Terms agricultural revolution anthropocentrism biocentrism campus sustainability conservation ethic control controlled experiment correlation data dependent variable descriptive science ecocentrism ecological footprint ecosystem services environment environmental ethics environmental justice environmental science environmental studies environmentalism ethical standards ethics experiment fossil fuels hypothesis hypothesis-driven science independent variable industrial revolution interdisciplinary Leopold, Aldo 8

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Muir, John natural capital natural resources natural sciences nonrenewable natural resources overshoot paradigm peer review Pinchot, Gifford predictions preservation ethic primary source relativists renewable natural resources science scientific method secondary source social sciences sustainability theory treatment universalists variables

Teaching Tips 1. Begin class by asking the students to define the term environment in their own words. Bring old magazines for the students to clip out a picture that matches their definition. Ask students to put their definitions and pictures on a note card to be submitted. At the end of the semester, return the note cards to the students and ask them to redefine the term based on what they learned during the course. Lead a discussion about how their definitions changed.

2. Print pictures of radically different environments—a human eyebrow, a sulfur spring, an apartment, etc. Have students judge whether or not the pictures represent environments, and if so, why they do (or do not). This helps students understand an all-encompassing definition of the term environment.

3. To teach the scientific method, present a situation to the class and ask students to work in groups to address the issue using the scientific process. For example: A farmer in South Carolina notices that the pond on his property has an unusually high amount of algae in it. Because of the algal growth, his cattle will not drink from the Copyright © 2025 Pearson Education, Inc.

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pond. What is happening, and what could he do? Based on this information (the observation), ask students to formulate a hypothesis, make a prediction, and design an experiment.

4. To make environmental science more appealing to students, present information about local environmental issues. When students are faced with environmental problems where they live, they see how they relate to them personally and realize that they can make a difference. One possibility is to look at the Environmental Protection Agency’s Superfund Sites in your state. The National Priorities List of sites in the United States can be found at: epa.gov/superfund/search-superfundsites-where-you-live. From there you can choose your state or territory. Click on any site shown on the state map to see site names and locations, and then click on the site name to go to a page devoted to that site, its description, cleanup approach, progress, potentially responsible parties, and many other site-related documents.

5. Ask students to conduct Internet research on Easter Island. What is it like today?

How many people live on the island? What are the main resources? Now research one of the success stories, the island of Tikopia, which lies in the Pacific Ocean east of Australia and New Guinea, west of Tonga and Fiji. Look in Jared Diamond’s book Collapse (2005, Viking Press) or at the Internet site: tannerlectures.utah.edu/_resources/documents/a-to-z/d/Diamond_01.pdf. Compare and contrast the stable culture that has lasted at least 3,000 years on Tikopia with the fallen and failed culture of Easter Island. What are the major differences in how the people approached the idea of sustainability?

6. Quick feedback: Use a technique known as “muddiest point” to assess student understanding of the material. During the last 5 minutes of class, pass out 3  5 cards (or have students use their own paper, but in a large class 3  5 cards will be faster to assess) and ask students, anonymously, to write down the one point from the day that they don’t quite grasp—the “muddiest point.” Students leave cards in a pile as they exit. You don’t need to read every one of them in a large class—a random sample of 20 will give you a good indication of whether there are a couple of concepts that many students find unclear and you need to go over again, or whether most students understood almost everything. The technique has two benefits: First, the students must engage in some higher-order thinking to quickly review the lesson and their notes, assessing for clarity; and, second, you will get a snapshot of whether there are small, scattered misunderstandings or a single issue that needs to be revisited. (From Thomas A. Angelo and K. Patricia Cross, Classroom Assessment Techniques: A Handbook for College Teachers, 2nd ed., 1993. JosseyBass Publishers, San Francisco.)

7. Divide the class into six teams. Assign a chapter from Overshoot by William Catton, Jr. (see Suggested Texts below) to each team. Ask students to summarize the main points, analyze the information presented by the author, and explain if or how the text is relevant today. Encourage discussion about how issues raised in the text were addressed with legislation and action, or not. Consider dividing students into small groups, each of which will have responsibility for making an oral presentation during the semester. This chapter’s group might seek out the current research on

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carbon sequestration by the oceans, terrestrial capture by forests, or direct burial of CO2 from power generation.

8. Consider dividing students into small groups, each of which will have responsibility for making an oral presentation during the semester. This chapter’s group might investigate the ecological footprint of the community where the school is located and explore sustainability issues there. Are there identifiable groups impacted by current transportation or energy issues in the community?

9. Service Learning: Ask students to brainstorm, individually or as a group, ways in which they might explore the issues of this chapter in their community and take action. A specific example might be to educate consumers about the use of phosphates in dishwashing detergents. If your course contains a community service component, some students might want to use an idea from this section as a project.

Additional Resources Websites 1. NASA Space link Curriculum Support, N ASA (nasa.gov/audience/foreducators/index.html) This website provides educator guides for life science activities that integrate the scientific method.

2. Sustainable Development Issues A to Z, United Nations Division of Sustainable Development (research.un.org/en) Information, documents, and publications related to sustainable development can be accessed from this website.

3. U.S. and World Population Clocks—Population Clocks, U.S. Census Bureau (census.gov/popclock) This website provides the current total populations of the United States and the world.

4. Galen Huntington’s Population Clock, University of California, Berkeley (galen.metapath.org/popclk.html) A population clock where you can pause the clock in time, go back to any time from 1950 until now, or go forward until 2100.

Audiovisual Materials 1. Planet Earth, 2007, produced by the B BC (bbc.co.uk/programmes/b006mywy) This series first aired on the Discovery Channel and captured the attention of diverse viewers. The compelling footage highlights many interesting and rare species and their habitat preferences, and also projects the viewer into the future, inspiring one to Copyright © 2025 Pearson Education, Inc.

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ask, “What next?” “What will happen if these areas and creatures are not recognized and protected?”

2. Planet in Peril, CNN, 2009, featuring Anderson Cooper, Jeff Corwin, and Dr. Sanjay Gupta (cnn.com/services/opk/planet.peril.intl/for.html) This documentary focuses on a current synthesis of Earth’s state of affairs, focusing on biodiversity and human population.

3. World in the Balance, 2004, produced by N OVA and distributed by W GBH/PBS (pbs.org/wgbh/nova/worldbalance/) This video is a 2-hour program that investigates social and environmental strains placed on the world due to rapidly increasing human populations.

Suggested Texts 1. Overshoot: The Ecological Basis of Revolutionary Change. 1980. William R. Catton, Jr. University of Illinois Press, Chicago. The term “overshoot” is used and described in your textbook. Overshoot, now several decades in print, was a validation of Garrett Hardin’s Tragedy of the Commons and Paul Ehrlich’s The Population Bomb.

Overshoot skillfully unpacks the growing dependence of human culture on technologies that enable the exploitation of more land. The book is sobering and well-written, with chapters that review issues such as carrying capacity, the cornucopian myth, drawdown, “cargoism,” overshoot, and crash.

2. Our Ecological Footprint: Reducing Human Impact on Earth. 1998. William E. Rees, Mathis Wackernagel, and Phil Testemale. New Society Publishers, Gabriola Island.

Our Ecological Footprint presents an internationally acclaimed tool for measuring and visualizing the resources required to sustain our households, communities, regions, and nations, converting the seemingly complex concepts of carrying capacity, resource use, waste disposal, and the like into a graphic form that everyone can grasp and use. An excellent handbook for community activists, planners, teachers, students, and policymakers.

3. Collapse: How Societies Choose to Fail or Succeed. 2005. Jared Diamond. Viking Press, New York. Academic and popular science author, Jared Diamond, reviews the causes of historical and pre-historical instances of societal collapse—particularly those involving significant influences from environmental changes, the effects of climate change, hostile neighbors, and trade partners—and considers the responses different societies have had to such threats.

Weighing the Issues: Facts to Consider Follow the Money Facts to consider: A researcher who obtains data showing his or her funding source in an unfavorable light may be reluctant to publish the results for fear of losing funding—or worse yet, could be tempted to doctor the results. This situation can arise, for instance, 12

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when an industry funds research to test its products for health or safety. Most scientists resist these pressures, but whenever you are assessing a scientific study, it is always a good idea to note where the researchers obtained their funding.

Environmental Justice?

Facts to consider: Remember that environmental justice involves the fair and equitable treatment of all people with respect to environmental policy and practice, regardless of income, race, or ethnicity. The answers to these questions will depend on the personal experience of the student, as well as what hometown, what section of your campus town, or what community college district they come from.

Leaving a Large Footprint Facts to consider: The science behind the ecological footprint can be found in Wackernagel and Rees’ text, Our Ecological Footprint (New Society Publishers, 1996), and a number of footprint calculators can be found online. The answers to these questions are clearly rooted in values, not in science, except that the authors make a strong case for our inability as a society to continue to use resources at our current rate, and that the richer nations are responsible for the excess use.

The Science Behind the Story: Thinking Like a Scientist What Are the Lessons of Easter Island?

Observation: Ever since European explorers stumbled upon Rapa Nui on Easter Sunday, 1722, outsiders have been struck by the island’s barren landscape. Early European accounts suggested that the 2000–3000 people living on the island seemed impoverished, subsisting on a few meager crops and possessing only stone tools. Yet the forlorn island also featured hundreds of gigantic statues of carved rock called Moai.

Question: How could people without wheels or ropes, on an island without trees, have moved 90-ton Moai statues as far as 10 km (6.2 mi) from the quarry where they were chiseled to the coastal sites where they were erected?

Hypothesis: Easter Island had once been lushly forested.

Experiment: Scientist John Flenley and his colleagues drilled cores deep into lake sediments and examined ancient pollen grains preserved there, seeking to reconstruct, layer by layer, the history of vegetation in the region.

Results: Finding a great deal of palm pollen, they inferred that when Polynesian people colonized the island (A.D. 300–900, they estimated), it was covered with palm trees.

Archaeologist Catherine Orliac found that at least 21 other plant species—now gone— had also been common. Clearly, the island had once supported a diverse forest. Forest Copyright © 2025 Pearson Education, Inc.

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plants would have provided fuelwood, building material for houses and canoes, fruit to eat, fiber for clothing—and, researchers guessed, logs and fibrous rope to help move statues. However, pollen analysis showed that trees began declining after human arrival and were replaced by ferns and grasses. Then between 1400 and 1600, pollen levels plummeted. Charcoal in the soil proved the forest had been burned, likely for slash-andburn farming. Researchers concluded that the islanders, desperate for forest resources and cropland, had deforested their own island. With the forest gone, soil eroded away (data from lake bottoms showed a great deal of accumulated sediment). Erosion would have lowered yields of bananas, sugarcane, and sweet potatoes, perhaps leading to starvation and population decline. Further evidence indicated that wild animals disappeared. Archaeologist David Steadman analyzed 6500 bones and found that at least 31 bird species provided food for the islanders. Today, only one native bird species is left. Remains from charcoal fires show that early islanders feasted on fish, sharks, porpoises, turtles, octopus, and shellfish—but in later years they consumed little seafood. As resources declined, researchers concluded, people fell into clan warfare, revealed by unearthed weapons and skulls with head wounds. Rapa Nui appeared to be a tragic case of ecological suicide: A once-flourishing civilization depleted its resources and destroyed itself.

Observation: The traditional “ecocide” interpretation didn’t tell the whole story.

Radiocarbon dating (dating of items using radioisotopes of carbon) indicated that people had not colonized the island until about A.D. 1200, suggesting that deforestation occurred rapidly after their arrival.

Question: How could so few people have destroyed so much forest so fast?

Hypothesis: When Polynesians settled new islands, they also brought rats.

Results: Researchers found rat tooth marks on old nut casings, and Hunt and Lipo suggested that rats ate so many palm nuts and shoots that the trees could not regenerate. With no young trees growing, the palm went extinct once mature trees died.

Observation: Hunt, Lipo, and others also unearthed old roads and inferred that the statues could have been moved by tilting and rocking them upright, much as we might move a refrigerator.

Hypothesis: Islanders had adapted to their resource-poor environment by becoming a peaceful and cooperative society, with the statues providing a harmless outlet for competition among family clans over status and prestige.

Results: Historical journals of sequential European voyages depict a society falling progressively into disarray as if reeling from epidemics. This resulted in a new hypothesis being formed—that the collapse of Rapa Nui’s civilization resulted from a barrage of disease, violence, and slave raids following foreign contact.

Observation: Hunt and Lipo’s interpretation would represent a paradigm shift in how we view Easter Island.

Hypothesis: Land use patterns were not consistent.

Experiment: In 2015, a six-person research team set out to estimate when human land use began to decline for each of three sites on the island. They did this by measuring how long ago pieces of obsidian rock at each site were unearthed from the soil and 14

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exposed to the air (obsidian absorbs water molecules very slowly, chemically changing over many years).

Results: The researchers found that land use had declined prior to European contact at a dry site and at a site with naturally poor soil, but that land use had continued at a moist site with fertile soil for farming. They proposed that the true picture was complex: Perhaps islanders had indeed degraded their environment in areas where conditions were sensitive but had sustained themselves in areas where conditions were more forgiving.

Question: Did the island’s population fall before or after European arrival?

Experiment: Recently scientists have begun using the distribution of radiocarbon-dated items through time to estimate past population sizes. In 2020, a team of researchers led

by Mauricio Lima of the Pontifical Catholic University of Chile used this technique and published research.

Results: They concluded that Rapa Nui’s population had fallen in three stages well before the arrival of Europeans and that the declines were correlated with climate change as the region became drier. They proposed that a drying climate made farming harder, driving people to cut down forest to expand room for agriculture. Robert DiNapoli of SUNY-Binghamton and others joined Hunt and Lipo to publish a paper challenging the Lima team’s conclusions. Di Napoli’s team did their own analysis of radiocarbon dates and ended up concluding that the population fell only after Europeans arrived.

Impact: Like the people of Rapa Nui, we are all stranded together on an island with limited resources. Any island population must learn to live within its means—but with care and ingenuity, there is hope that we can.

Answers to End-of-Chapter Questions Testing Your Comprehension 1. Human population grew markedly as a result of both the agricultural and industrial revolutions. The agricultural revolution made it easier for humans to meet their nutritional needs than as hunter-gatherers; thus they lived longer and had more children. The industrial revolution brought improved sanitation and medical technology, and increased agricultural productivity fueled by fossil fuels and fertilizer.

This significantly increased life expectancy, decreased mortality, and expanded the capacity to feed a growing population.

2. An ecological footprint expresses the cumulative area of biologically productive land and water required to provide the resources a person or population consumes and to dispose of or recycle the waste the person or population produces. It measures the total area of Earth’s biologically productive surface that a given person or population “uses” once all direct and indirect impacts are totaled up. For humanity as a whole, Wackernagel and his colleagues at the Global Footprint Network calculate that we are now using 71% more of the planet’s resources than are available on a Copyright © 2025 Pearson Education, Inc.

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sustainable basis. That is, we are depleting renewable resources by using them 71% faster than they are being replenished. This is like drawing money out of a bank account rather than living off the interest the money makes. This excess use is termed overshoot because we are overshooting, or surpassing, Earth’s capacity to sustainably support us.

3. Environmental science seeks to understand how Earth’s natural systems function, how humans are influenced by them, and how we are influencing them. It includes the disciplines of ecology, earth sciences, economics, political science, demography, and ethics, among others.

4. Science is both the systematic process for learning about the world and the accumulated body of knowledge that arises from this process. It can be applied to the development of new technologies, such as electrical lighting, nuclear power, and antibiotics. It can also be applied to policy decisions and resource management strategies.

5. The scientific method includes making observations, asking questions, developing a hypothesis, making predictions, and testing those predictions, often by means of an experiment. Before being published, a researcher’s results go through a process of peer review, which provides a valuable guard against faulty science contaminating the literature.

6. Anthropocentrism describes a human-centered view of the environment. Biocentrism ascribes value to certain living things, or to the biotic realm in general; this encompasses anthropocentrism, but takes this concept further to embrace other living things. Ecocentrism is the most holistic and judges actions in terms of their effects on whole ecological systems. An anthropocentric individual would think a shopping mall is good, providing many goods to human beings. Biocentrics would see the mall as bad, as the building of it pushes other organisms out of their habitat.

Ecocentrists would also see the mall as a drawback, as it is built over an ecosystem.

7. The preservation ethic holds that we should protect our environment in a pristine, unaltered state. Conservation states that people should put natural resources to use, but that we have a responsibility to manage them wisely. John Muir was motivated by the rapid deforestation of North America, and promoted the preservation ethic.

Gifford Pinchot took a more anthropocentric view of how and why we should value nature, and supported conservation.

8. Aldo Leopold’s land ethic is based on the idea that healthy ecological systems depend on protecting all their interacting parts. Leopold argued that people should view themselves and “the land” as members of the same community, and that we are obligated to treat the land in an ethical manner.

9. Environmental justice involves the fair and equitable treatment of all people with respect to environmental policy and practice, regardless of their income, race, or ethnicity. Answers to the second part of the question will differ by student.

10. Sustainability means living within our planet’s means, such that Earth can sustain us—and all life—for the future. There will be differing answers to the second part of the question, depending on the college.

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Calculating Ecological Footprints

Nation

Ecological footprint (hectares per person)

Proportion relative Proportion relative to world average to world area footprint available

Bangladesh

0.7

0.27 ( 0.7  2.58 )

0.46 ( 0.7  1.51)

Tanzania

0.9

0.35

0.60

Colombia

2.0

0.77

1.32

Thailand

2.3

0.89

1.52

Mexico

2.3

0.89

1.52

Sweden

4.9

1.90

3.24

United States

7.5

2.91

4.97

World average

2.58

1.0 ( 2.58  2.58 )

1.71 ( 2.58  1.51)

Your personal footprint (see Question 4)

Answers will vary

Answers will vary

Answers will vary

1. Bangladesh has a low per-capita income; it consumes little and creates little waste. Also, due to high population density, the average citizen has less access to natural resources, such as fresh water and fossil fuels.

2. The United States has a high per-capita income; it consumes more than its fair share and creates great amounts of waste, some of which is not biodegradable or recyclable. Despite the population density being much lower in the United States—almost the same land area of China, but one-fourth of its population— the people in the United States still consume more natural resources than the world average.

3. Higher per-capita income suggests a higher consumption of goods that require natural resources in their production. An ecological footprint can be decreased in wealthy countries by using money to develop renewable resource technology— this can range from simpler projects, like building efficient recycling facilities, to more complex ones, like expanding hydrogen technology.

4. Answers will depend on the student and his or her results.

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CHAPTER 1 Science and Sustainability 17

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