Section Review Questions

Chapter L, Introduction

Section L.1

1. What is your strongest learning style?

Answers will vary, but students should examine their own behavior patterns and preferences.

2. What are the five techniques of the SQ3R method for studying?

These methods are listed in table L3. They include Survey (the information in the chapter), Qeuestion (yourself about main issues in the readings), Read (in small segments), Recite (ideas you have just read), and Review (main ideas after reading).

Section L.2

1. Describe seven attitudes needed for critical thinking.

In the section “What do I need to think critically?” is a list of attitudes and dispositions needed for well-reasoned analysis. These include skepticism and independence, open-mindedness and flexibility, accuracy and orderliness, persistence and relevance, contextual sensitivity and empathy, decisiveness and courage, and humility.

2. List six steps in critical thinking.

Identify and evaluate premises; acknowledge and clarify uncertainties; distinguish between facts and values; recognize and assess assumptions; distinguish the reliability ofa source; recognize and understand conceptual frameworks.

Chapter 1

Section 1.1

1. Why is population an important question in environmental science? In what ways is population less of a problem than in earlier years?

Both the total population and the rate of consumption per person are of concern in environmental science. More people (and especially more wealthy people) consume more resources, destroy more habitat, and create more pollution. Nevertheless, there are signs that population growth is stabilizing nearly everywhere. If we all convert to more sustainable lifestyles, we could minimize our impacts.

2. In what ways is pollution still a problem? Has it improved? Why?

Although air and water quality have improved dramatically in most developed countries, we still emit more pollution than can be cleaned up by ecological systems. These improvements are due to better public understanding of environmental issues and demands for protective legislation.

We’re now particularly about long-lived, highly toxic materials, such as mercury and lead, that have deleterious effects at extremely low levels that may not be manifest for years or decades and act in subtle ways to disrupt endocrine regulation or other fundamental controls on growth and development.

3. What is an “ecological footprint”?

An ecological footprint is a measure of our environmental impacts. It’s generally calculated using a few standard measurements that can be converted (somewhat controversially) into global hectares (of productive land) that would be needed to support each activity we undertake.

Section 1.2

1. Differentiate “conservation” and “preservation.” Identify one person associated with each.

Conservation usually means wise use of resources to make them last as long as possible, but still use, nonetheless. Gifford Pinchot was an important proponent of conservation. Preservation emphasizes the protection of organisms and resources for their own sake regardless of their utility to us. John Muir pioneered many of our ideas about preservation.

2. What was Rachel Carson’s Silent Spring about? Why?

Silent Spring was concerned with the dangers of chemical pollution and especially its effects on human health. Rachel Carson’s interest in this topic began after the Second World War, when there was a great explosion of synthetic chemical use (most of which hadn’t been sufficiently tested) in every walk of life.

3. In what ways is environmental quality tied to social progress?

Increasingly, environmental activists are linking environmental quality and social progress on a global scale. One of the core concepts of modern environmental thought is sustainable development, the idea that economic improvement for the world’s poorest populations is possible without devastating the environment. A core belief is that as we become wealthier and more technologically advanced, we become more interested in environmental quality, we have the resources and technology to improve our environment.

Section 1.3

1. List any three quality of life indicators (table 1.1). How do they differ between wealthy and poor countries?

GDP I at least 35 times higher, the poverty index is about 60% lower, and life expectancy is about 23% higher in most developed countries compared to the least-developed countries.

2. Why is affluence a liability? Give an example.

Affluence makes it possible for us to follow our worst impulses to the detriment of our own health and well-being as well as the quality of our environment.

3. Why are many ecologists skeptical about the idea of sustainable development?

Development generally means more resource consumption. Many ecologists doubt we can do that sustainably.

Section 1.4

1. Think of five ecosystem services on which you rely.

Photosynthesis, carbon capture, nutrient recycling, water purification, and temperature regulation (as well as food and fuel supply).

2. What is the “tragedy of the commons”? List any two of the factors that can help communities manage a commons.

The “tragedy of the commons” is an idea proposed by Garrett Hardin in 1968 claiming 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 because each of us acts only in our own self-interest motivated primarily by fear and greed. However, there are many cases of successful long-term management of common-property resources, such as sustainable fisheries, common forests, and grazing lands, in communities around the world. Among the requirements for communal resource management are (1) effective and inexpensive monitoring of resource use; (2) an ability to exclude outsiders, who don’t understand rules of use; and (3) frequent face-to-face communications and strong social networks among users.

3. List several concerns of the Millennium Development Goals.

The Millennium Development Goals include ending poverty and hunger, universal education, gender equity, child health, maternal health, combating HIV/AIDS, environmental sustainability, and global cooperation in development efforts. Many of these goals emphasize health and rights for women and children, who traditionally have little access to resources, education, health care, or political rights in many developing areas.

Section 1.5

1. Explain the idea of moral extensionism, and give an example.

Moral extensionism expands our concepts of inherent value—that someone or something has value for its own sake-from ourselves to our community, to other groups, and other organisms or even the whole universe. Aldo Leopold’s essay “Thinking like a Mountain” or Christopher Stone’s Should Trees have Standing? Have both transformed our understanding of this idea.

2. How does inherent value differ from instrumental value?

Inherent value implies moral standing and intrinsic rights while instrumental value is based on usefulness to someone else. You have intrinsic rights, but your hammer has only instrumental value.

3. Why is stewardship important in many faiths?

Many faiths believe that God (or Gods) created the earth and entrusted it to our stewardship.

4. What is environmental justice?

Environmental justice combines civil rights with environmental protection to demand a safe, healthy, life-giving environment for everyone.

Chapter 2

Exploring science questions/ Test your comprehension

1. What is a mean? How would you use one?

A mean is an average for a group of samples, that is, the sum of all values divided by the number of values in the group. We use mean values to describe and compare groups, as in the case of national income or educational attainment.

2. What is a Gaussian or normal distribution? What shape does it create in a graph?

A normal or Gaussian frequency distribution is a symmetrical, bell-shaped distribution, with the mean is near the center of the range of values and most values are fairly close to the mean.

3. What do statisticians mean by confidence limits?

When you calculate a mean or other statistical measure, you are often estimating what that value would be for any sample of the population. Confidence limits (or levels, or intervals) indicate where that value probably falls for a different sample of the same population.

Section 2.1

1. What is science? What are some of its basic principles?

Science is a process for producing knowledge methodically and logically. Some of the basic principles of science are empiricism, uniformitarianism, parsimony, uncertainty, repeatability, an assumption that proof is elusive, and a demand for testable questions.

2. Why are widely accepted, well-defended scientific explanations called “theories”?

Ideas and explanations in science are always open to revision and correction as further evidence emerges. Scientists try to be cautious about proof, so they use the term “theory” to describe many explanations that are supported by the overwhelming weight of available data and experience, and are generally accepted as fact by the scientific community.

3. Draw a diagram showing the steps of the scientific method, and explain why each is important.

A diagram of the scientific process should look very much like figure 2.3.

Section 2.2

1. Why are systems important in our environment?

Systems are important in environmental science because they help explain relationships.

2. What are feedback mechanisms?

A feedback mechanism is a process that either leads to enhanced or suppressed change in a system. A positive feedback is self-enhancing: plant growth produces more leaves which leads to more plant growth, and the process continues. A negative feedback suppresses change in a system: plant growth demands light and moisture, which reduces available light and moisture, which slows plant growth.

3. Describe some emergent properties of ecosystems.

Emergent properties are characteristics that belong only to the entire system and not to any of the component parts. That is, the properties arise from the organization of the system.

Section 2.3

1. Why do we say that proof is elusive in science?

There’s always a chance that some unknown factor will change our assessment. Therefore we almost never claim to have proven anything conclusively in science. We normally say that the evidence supports or disproves a hypothesis or theory.

2. How can we evaluate the validity of claims about science?

We can evaluate the validity of claims by asking the questions in Table 2.2.

3. What is the role of consensus in science?

Consensus is important in science because it represents a process in which ideas and information are exchanged, debated, and tested to create a general agreement among informed scholars.

Chapter 3

Section 3.1

1. Define atom and element. Are these terms interchangeable?

Elements are substances that cannot be broken down into simpler forms by ordinary chemical reactions. No: Atoms are the smallest particles that exhibit the characteristics of an element. Element is a general term, while atoms are individual examples of that general category.

2. Your body contains vast numbers of carbon atoms. How is it possible that some of these carbon atoms may have been part of the body of a prehistoric creature?

Matter is constantly recycled and reused. An individual carbon atom may have been part of many different organisms over the billion year history of life on earth.

3. What are six characteristics of water that make it so valuable for living organisms and their environment?

Water molecules are polar; they exist as a liquid at ambient temperatures; they are cohesive and expand when crystalized; they have a high heat of vaporization and a high specific heat (see Exploring Science, p. 55).

Section 3.2

1. Restate the first and second law of thermodynamics.

The first law of thermodynamics states that energy is neither created nor destroyed under normal conditions. The second law says that, with each successive energy transfer or transformation in a system, less energy is available to do work and entropy increases. Everything in nature tends to fall apart, slow down, and get more disorganized.

2. The oceans store a vast amount of heat, but why (except for climate moderation) is this huge reservoir of energy of little use to humans.

The ocean stores a huge amount of heat because of the high specific heat of water and the huge volume of the oceans, but the heat isn’t of much use to us because it’s dispersed and low temperature (see next question).

3. Explain the difference between high-quality and low-quality energy.

High-quality energy is intense, concentrated, and high in temperature and is useful in carrying out work. The intense flames of a very hot fire or high-voltage electrical energy are examples of high-quality forms that are valuable to humans. Low-quality energy is difficult to gather and use for productive purposes because it is diffused, dispersed, and low in temperature.

Section 3.3

1. What is the source of carbon for green plants?

The carbon for green plants comes from the atmosphere in the form of carbon dioxide.

2. What is one product of photosynthesis?

The initial products of photosynthesis are sugars, such as glucose.

3. How are photosynthesis and respiration related?

These two processes are essentially inverse of each other. Photosynthesis uses energy, carbon dioxide and water to create sugars and other organic compounds. Respiration breaks down those organic compounds to release energy, carbon dioxide and water.

Section 3.4

1. Describe the following: producers; consumers; secondary consumers; decomposers.

Producers are the plants or chemosynthetic bacteria at the bottom of the food chain that carry out photosynthesis and create organic matter. Primary consumers are the herbivores that eat plants, secondary consumers are the carnivores that eat other animals, decomposers are the organisms that break down and recycle dead organisms.

2. Ecosystems require energy to function. Where does this energy go as it is used? How does the flow of energy conform to the laws of thermodynamics?

The energy used by organisms for thermal regulation or work eventually dissipates to the environment (and eventually out to space) as heat. At each use of energy or transfer of energy from one organism to another, entropy increases and some of the energy is lost to inefficiency according to the second law of thermodynamics.

3. Why are there generally fewer organisms at the top of the food pyramid than at the bottom?

Because of the second law, some energy is lost between each trophic layer in an ecosystem. Thus, it takes more organisms at lower layers to support each individual at the next higher level. The ratio, in fact, is often about ten to one.

Section 3.5

1. What do we mean by carbon-fixation or nitrogen-fixation? Why is it important to humans that carbon and nitrogen be “fixed”?

When carbon or nitrogen are captured and incorporated into organic materials, we say they have been fixed (that is they’re no longer gaseous and mobile). We need carbon and nitrogen-containing compounds to live, and we can’t fix (or synthesize) them ourselves.

2. Why is nitrogen important to living things? What type of organism is responsible for making nitrogen available to plants?

Nitrogen is essential in amino acids, which are the backbone of proteins, which are essential to all life. Nitrogen-fixing bacteria, often residing in plant root nodules, carry out most natural nitrogen fixation.

3. In what forms is carbon stored in oceans, the atmosphere, living things, and rocks?

The description of the carbon cycle is rather abbreviated in this chapter, but carbon in the atmosphere is almost entirely carbon dioxide, while that in ocean water is mostly in dissolved carbon dioxide or carbonic acid. In ocean sediments, carbon is present in calcified organic material, or, more commonly, as calcium carbonate in the skeletons of marine organisms. Carbon in living things is most often calcium carbonate in shells or skeletons, while the carbon in rocks is usually in carbonate minerals, such as calcite, dolomite, etc.

Chapter 4

Section 4.1

1. Explain how tolerance limits to environmental factors determine distribution of a highly specialized species such as the saguaro cactus.

An organism’s physiology and behavior allow it to survive only in certain environments. Temperature, moisture level, nutrient supply, soil and water chemistry, living space, and other

environmental factors must be at appropriate levels for organisms to persist. Tolerance levels describe the critical factors that determine where a species lives.

2. Describe how evolution produces species diversity.

The basic idea of evolution is that species change over generations because individuals compete for scarce resources. Better competitors in a population survive and reproduce more successfully, and their offspring inherit the beneficial traits. Over time, populations change enough to become different species from their ancestors or from neighboring populations.

3. Define selective pressure and describe how it affects species.

Selective pressures are environmental factors that lead to evolutionary change.

Section 4.2

1. The most intense interactions often occur between individuals of the same species. What concept discussed in this chapter can be used to explain this phenomenon?

Members of the same species compete for the same resources. Different species are more likely to use different resources, making competition less intense.

2. Explain how predators affect the adaptations of their prey.

Because predators usually prey more effectively on weak or poorly defended prey, survivors in a prey population tend to be those that are stronger or better defended. For example antelopes that can run fastest are most likely to pass on their genes to the next generation.

3. Describe how competition for a limited quantity of resources occurs in ecosystems.

When species and individuals compete, there can be physical conflict, but more often there is some form of resource allocation, often involving adaptation and niche specialization.

Section 4.3

1. Which ecosystems have the greatest biological productivity?

Tropical rainforests and coral reefs have the greatest biological productivity among all major biomes.

2. What are resilience and stability?

Resilience is the ability to recover from disturbance; stability is the ability to resist disturbance.

3. What are ecological edge effects?

Edge effects are ecological conditions at the boundary between adjacent biomes. Predator activity, sunlight and plant growth, or other conditions may be different at edges of contrasting habitat types.

Section 4.4

1. Describe the process of succession that occurs after a forest fire destroys an existing biological community.

When a forest fire destroys an existing biological community, secondary succession results in a serial colonization that can rebuild the community. The pioneer species are generalists that disperse well and can survive in harsh conditions of full sun, heat, and periodic dryness. Soon, long-lived and deep rooted perennial grasses, herbs, shrubs, and, eventually, trees take hold if the climate and soil permit.

2. Discuss the dangers posed to existing community members when new species are introduced into ecosystems.

Introduced invasive species can profoundly alter biological communities. If they are aggressive generalists, they can outcompete and out-reproduce local species that are adapted to more stable and specialized conditions. A lack of predators and diseases in their new environment also gives invasive species an advantage.

Chapter 5

Section 5.1

1. A grassland biome occupies much of the center of North America. Why is this, in terms of environmental factors?

The Great Plains grasslands have high summer and low winter temperatures. Rainfall ranges from about 25 to 40 cm per year, which is too little for most tree species. Historically, frequent fires also suppressed trees and shrubs.

2. What is taiga and where is it found? Why might taiga be slower to recover from logging than southern forests?

The extreme, ragged edge of the boreal (or northern) forest, where trees gradually give way at far northern latitudes around the world to open tundra, is known by its Russian name, tiaga. Here the extreme cold and short summers limit the regrowth of trees after logging.

3. Why are tropical moist forests often less suited for agriculture and human occupation than tropical deciduous forests?

Moist tropical forests (also called rainforests) are less suited for agriculture and human habitation because they tend to have thin, acidic, iron-rich, nutrient-poor soils and high levels of insect, fungi, and other pests that threaten crops and humans alike.

4. Find out the annual temperature and precipitation conditions where you live (fig. 5.2). Which biome type do you occupy?

Answers will vary according to location.

Section 5.2

1. How do physical conditions change with depth in marine environments?

Light and temperature decrease rapidly as depth increases, while pressure increases exponentially.

2. Describe four different coastal ecosystems.

Benthic communities occur on the bottom, and pelagic (from “sea” in Greek) zones are the water column. The epipelagic zone (epi = on top) has photosynthetic organisms. Below this are the mesopelagic (meso = medium), and bathypelagic (bathos = deep) zones. The deepest layers are the abyssal zone (to 4,000 m) and hadal zone (deeper than 6,000 m). Shorelines are known as littoral zones, and the area exposed by low tides is known as the intertidal zone. A broad, relatively shallow region along a continent’s edge, is called the continental shelf.

3. What is coral bleaching?

When seawater warms above a critical temperature, coral polyps expel their endosymbiotic algae and lose both their color and food source. If this condition persists, the corals die.

Section 5.3

1. Describe four different kinds of wetlands.

All wetlands are shallow enough to have rooted vegetation that emerges above the surface. Swamps, or wooded wetlands, are wetlands containing trees. Marshes have no trees but have emergent grasses, rushes, and other plants. Bogs are acidic and have deep layers of undecomposed moss and other plants. Fens are like bogs but are mainly fed by groundwater, and they tend to be less acidic than bogs.

2. Why are wetlands sites of high biodiversity and productivity?

Wetlands have abundant moisture and sunshine (because they are shallow), so that plants tend to grow vigorously and primary productivity is high.

Section 5.4

1. What percentage of temperate grasslands and forests are disturbed (table 5.1)? Why?

81.9% of temperate forests and 40.4% of temperate grasslands have been disturbed primarily by logging, urbanization, and overgrazing.

2. What is one reason for clearing of tropical coastal mangroves?

Coastal mangroves are often cleared to build shrimp ponds. This is a leading cause of mangrove losses in many areas. Mangroves are also felled for firewood and to create better views for beach resorts.

3. How have temperate wetlands in the United States been lost?

Wetlands are drained and filled for agriculture and urban development or lost to erosion. Iowa, for example, is estimated to have lost 99% of its wetlands.

Chapter 6

Section 6.1

1. What factors caused the collapse of bluefin tuna populations?

Overfishing is the primary cause of decline in Bluefin tuna populations. Pollution and overfishing of prey species also play a role, but overfishing is the dominant cause of tuna declines.

2. Define exponential growth and logistic growth.

Exponential growth is growth at a constant rate of increase per unit of time. It can be expressed as a constant fraction of exponent. Logistic growth is regulated by internal or external factors so an equilibrium is established with environmental resource.

3. Explain these terms: r, N, t, dN/dt.

In a population dynamics study, r is the rate of growth, N is the number of individuals in the population at a given time, t is a particular time, and dN/dt is the rate of change in the population size over time.

Section 6.2

1. Describe three major types of survivorship patterns, and explain what they show about a species’ role in its ecosystem.

Some organisms, such as elephants tend to all live to old age. Others, such as sea gulls, have a fairly constant mortality at all age levels. Still other organisms, such as clams and redwood trees, have a high mortality rate early in life but live a full life if they reach adulthood.

2. Explain how biotic and abiotic factors affect population growth.

Biotic factors that affect survival include competitors, predators, and diseases. Abiotic factors are physical or chemical conditions in the environment including temperature, water, weather, shelter, or nutrients that influence survival.

3. What are the main interspecific population regulatory interactions? How do they work?

Interspecific population interactions are the same as biotic factors: competition, predation, and diseases.

Section 6.3

1. What is island biogeography and why is it important in conservation biology?

Island biogeography is a framework for the study of population dynamics in isolated situations, such as actual islands or patches of habitat in the midst of incompatible conditions. The framework derives from the theory of island biogeography (R.H. MacArthur and E.O. Wilson, 1967), which proposed that species diversity is a function of island size and isolation. Large or near islands should have more species than small or remote islands.

2. Why does genetic diversity tend to persist in large populations, but gradually drift or shift in small populations?

Genetic diversity tends to persist in large populations because they are likely to have more diversity to start with, and because random mutations or events affect a smaller proportion of the population than they do in a smaller sample size. Genetic drift has a more pronounced effect in a smaller population because in a small population, a randomly changed trait is more likely to be passed on than in a very large and diverse population.

3. Define the following: metapopulation, genetic drift, demographic bottleneck.

A metapopulation is a collection of populations that have gene flow between geographically separate units. Genetic drift is a gradual change in gene frequencies due to random events. A demographic bottleneck occurs when just a few members of a species survive a catastrophic event or colonize new habitat isolated from other members of the same species.

Chapter 7

Section 7.1

1. At what point in history did the world population pass its first billion? What is the total population now?

The world population reached 1 billion sometime in the 18th century.

2. What factors contribute to rapid population growth?

Access to the basic necessities of life: food, water, shelter, health care, safety, and freedom affect reproduction and population growth. The need for children in farm work and to support parents in old age also affect population growth, as do religious beliefs and cultural norms.

3. What factors help control population growth?

Education, expansion of women’s rights, and economic opportunities for women, along with urbanization, industrialization, increased child survival, access to family planning, and expansion of the social safety net so that having a large family is no longer economically necessary all tend to reduce birth rates.

Section 7.2

1. Who was Thomas Malthus, and why was he worried about population growth?

Thomas Malthus was an Anglican minister and an economist who wrote An Essay on the Principle of Population in 1798. He believed that populations naturally overbreed and outstrip food supplies resulting in starvation, crime, war and misery.

2. How could technology increase human carrying capacity?

Technology can extend the carrying capacity of our environment by providing more food, shelter, and other necessities of life. For example, although the world population is now about

seven times what it was in Malthus’ day, the average food supply is actually greater than it was then due to increases in agricultural technology.

3. What is the I=PAT formula, and what does it mean?

I=PAT refers to the principle that environmental Impact depends on Population, Affluence, and Technology. These three factors all tend to increase the amount of resources we consume.

Section 7.3

1. What is the replacement rate of births?

The replacement rate of births is 2.1 children per couple.

2. What is the relation between income and life expectancies?

In general, as incomes rise, so do life expectancies because with more money, people can afford better food, health care, etc.

3. What factors increase or decrease our desire for children?

The role of children supporting their parents in old age is one of the strongest motivations for families. If that role decreases, the desire for large families also decreases. Child survival also affects reproductive decisions. If most of your children die at an early age, you need to have more children if some are to survive to adulthood. Male pride and women’s place in society along with religious beliefs and cultural norms also affect reproductive choices. On the other hand, living in an urban environment where space is limited and it’s more expensive to raise children can decrease the desire to have more children. In an urban family, it can make economic sense to have fewer children and to spend more time and resources on a smaller family.

Section 7.4

1. How can prosperity and urbanization affect birth rates?

In rural, less developed societies, children are essential to support their parents in old age. If most of your children die at an early age, you need to have more children to have some survive to adulthood. Education, expansion of women’s rights, and economic opportunities for women, along with industrialization, increased child survival, access to family planning, and expansion of the social safety net all tend to be more available in wealthier, more developed, urban societies thus making family planning more attractive and more feasible. Furthermore, living in an urban environment where space is limited and it’s more expensive to raise children can decrease the desire to have more children. In an urban family, it can make economic sense to have fewer children and to spend more time and resources on a smaller family.

2. What’s the role of women’s rights in population growth?

When women have more rights, more personal control over their finances, and better education, they tend to have fewer children and to spend more time and resources on raising the ones they have.

3. Why is Brazil a useful model in demographics?

Brazil is interesting because as a predominantly Catholic country where birth control is officially prohibited and society is highly patriarchal, you would expect birth rates to be high. Nevertheless, in spite of the fact that the country has no official family planning policies or programs, a rapid demographic change has occurred anyway. This suggests that a similar shift could occur in many other countries.

Chapter 8

Section 8.1

1. What is BPA and how might you be exposed to it?

Bisphenol A is a key ingredient of both polycarbonate plastics and epoxy resins. It’s widely used in items ranging from baby bottles, eyeglass lenses, water pipes, linings of cans and bottles, and tooth-protecting sealants. It can leach out of plastics into food and beverages.

2. What are emergent diseases? Give a few examples, and describe their cause and effects.

Emergent diseases are those not previously known or that have been absent for at least 20 years. The new strain of swine flu now spreading around the world is a good example, as are drug-resistant tuberculosis and mad cow disease. They can cause acute epidemics because we don’t have natural defenses against them and because we don’t know how to monitor or prevent their spread.

3. How does antibiotic resistance arise? How do hospitals and feedlots contribute to this phenomenon?

Antibiotic resistance occurs when antibiotics are widely distributed in the environment. This exerts selective pressure in that bacteria with spontaneous mutations to antibiotics survive and pass resistant genes on to their progeny. Bacteria can also exchange DNA with unrelated species so that resistance spreads quickly through populations. Our careless overuse of antibiotics in hospitals and feedlots is a main driver in this process.

Section 8.2

1. What are endocrine disrupters and why are they dangerous?

Endocrine disrupters are chemicals that disrupt normal hormone functions. We now know that some of the most insidious effects of persistent chemicals such as BPA, dioxins, phthalates, and PCBs are that they interfere with normal growth, development, and physiology of a variety of animals—including humans—at very low doses.

2. What are teratogens and mutagens?

Teratogens are chemicals or other factors that specifically cause abnormalities during embryonic growth and development. Mutagens are agents, such as chemicals and radiation, that damage or alter genetic material (DNA) in cells. This damage can lead to birth defects if it occurs during embryonic or fetal growth. Later in life, genetic damage may trigger neoplastic (tumor) growth. When damage occurs in reproductive cells, the results can be passed on to future generations.

3. How does diet influence health?

If you don’t have the right kinds and amounts of nutrients, your health can be compromised. Furthermore, one of the main routes of entry for toxins into our bodies is through diet.

Section 8.3

1. What is biomagnification, and why is it important?

Biomagnification occurs when the toxic burden of a large number of organisms at a lower trophic level is accumulated and concentrated by a predator in a higher trophic level. In higher trophic levels, the concentrations of toxins can reach dangerous levels.

2. How do the physical and chemical characteristics of materials affect their movement, persistence, distribution, and fate in the environment?

Solubility and mobility determine where and when chemicals move through the environment and in our bodies. Persistent materials, such as heavy metals and some organic compounds, can accumulate and concentrate in food webs so they reach toxic concentrations in top predators.

3. Give three examples of persistent organic pollutants and describe their main effects.

Lead is a neurotoxin that persists in the environment and can cause brain damage even at very low concentrations if it enters the body. Perfluorooctane is used to make non-stick cookware and stain-resistant products. It can cause liver damage as well as cancer and reproductive or developmental problems. Phthalates are found in a wide variety of consumer products and can act as endocrine disrupters.

Section 8.4

1. Why is there a threshold in response to some toxins?

Thresholds occur because organisms often have defense mechanisms that either prevent the toxin from reaching its target in an active form or repairs the damage that it causes.

2. What is an LD50?

This is the dose of a toxin that is lethal to 50 percent of a population.

3. What is the difference between acute and chronic doses and effects?

An acute effect is caused by a single exposure to a toxin and result in an immediate health crisis of some sort. An acute dose causes an acute effect. Chronic effects, on the other hand, are long-lasting, perhaps even permanent. A chronic effect can result from a single dose of a very toxic substance, or it can be the result of a continuous or repeated sub-lethal exposure.

4. What is the difference between acute and chronic toxicity?

Acute toxicity causes an immediate health crisis, while chronic toxicity causes long-lasting, but generally sub-lethal effects.

Section 8.5

1. Why has it been so difficult to regulate endocrine disrupters?

The effects of endocrine disrupters are often subtle and there are many factors that can cause the same symptoms, making it difficult to prove the effects of a particular factor. Furthermore, the consequences of an exposure can be delayed.

2. What is the “Precautionary Principle”?

This principle states we shouldn’t do things until we know they’re safe. The burden of proof for safety should be placed on those who want to make a change rather than requiring victims to prove what caused their symptoms.

Chapter 9

Section 9.1

1. How many people in the world are chronically undernourished? What does chronically undernourished mean?

Despite abundant production, some 870 million people in the world today are considered chronically undernourished, getting less than the minimum 2,200 kcal per day.

2. List at least five African countries with high rates of hunger (fig. 9.3; use a world map to help identify countries).

Zimbabwe, Botswana, Zambia, Mozambique, Malawi, Tanzania, Kenya,, Democratic Republic of Congo, Sudan, Ethiopia, and Niger all have high levels of hunger.

3. What are some of the health risks of overeating? What percentage of adults are overweight in the United States?

Being overweight substantially increases risk of hypertension, diabetes, heart attacks, stroke, gallbladder disease, osteoarthritis, respiratory problems, and some cancers. Some 64 percent of adult Americans are overweight, and about one-third are seriously overweight, or obese.

Section 9.2

1. Why does meat use more inputs than plant foods?

Modern meat production is based on energy- and water-intensive farming practices. It also takes high inputs of water and energy to prepare meat and get it to market in modern food distribution systems. It takes about 16 times as much fossil fuel energy to produce a kilogram of beef as it does a kg of vegetables or rice.

2. List several benefits and costs of fish and shrimp farming.

Wild-caught shrimp and fish are subject to the “tragedy of the commons” where no one has an incentive to conserve or sustain them. Farm-raised shrimp and fish are more likely to be raised with attention to efficiency. It takes less energy to harvest farmed species, and they don’t encourage “by-catch” or accidental destruction of non-target species as much as wild-caught

techniques. However, we’re still depleting wild species to provide food for captive populations. Building farm facilities often cause destruction to coastal areas, and waste products from pens pollute nearby areas. The high concentrations of fish and shrimp in farm operations foster disease and pests and result in overuse of pesticides and antibiotics.

3. Why are antibiotics used in livestock production?

Continuous, low-level use of antibiotics help livestock grow faster, remain healthier on feed that is not suited to their digestive systems, and resist disease in crowded conditions.

4. What is rotational grazing? What are its benefits?

Rotational grazing uses small, easily moved electric fences to concentrate grazing in one area of a field at a time. Animals are moved regularly (as much as every day). This can invigorate pasture, distribute manure, and keep livestock healthy

Section 9.3

1. What is the “green revolution,” and why was it important?

The green revolution involves crossbreeding plants with desired traits created new, highly productive hybrids known as “miracle” varieties. The first of these was a dwarf, high-yielding wheat developed by Norman Borlaug. These genetically engineered crops (whether created by conventional breeding or DNA transfers in the laboratory) often are more productive than traditional varieties and have contributed to expanded food supplies.

2. What are genetically modified organisms?

Genetic engineering involves removing genetic material from one organism and splicing it into the chromosomes of another organism. It is now possible to build entirely new genes by borrowing bits of DNA from completely unrelated species, or even synthesizing artificial DNA sequences to create desired characteristics in genetically modified organisms (GMOs).

3. Why are most U.S. corn and soybeans GM varieties?

With inputs of fertilizer, herbicides, and irrigation, GM corn and soy (and other crops) can produce higher yields than non-GM varieties. These inputs are expensive, but payments for corn and soy are high and can make these expensive varieties profitable.

Section 9.4

1. How is money spent supporting agriculture?

Agriculture subsidies include direct payments, price supports, aid for inputs such as irrigation. Over the past decade, the United States, for example, has spent $143 billion in farm support. Other wealthy countries have spent comparable amounts.

2. What are the primary uses of corn in the United States?

In the U.S., nearly all corn is used for livestock feed or to produce ethanol.

3. How can farm policy protect the land?

Farm policy could encourage conservation easements, wetland protection, erosion control, and other measures that protect the land, soil, water, and biodiversity.

Chapter 10

Section 10.1

1. What are six major components of soil?

Sand and gravel, silts and clays, dead organic material, fauna and flora, water, and air.

2. How are soil organisms important for good soils?

Soil bacteria, algae, and fungi decompose and recycle leaf litter, making nutrients available to plants. These microscopic life forms also help to give soils structure and loose texture

3. Why are Brazilian soils often red?

Tropical soils are often iron-rich and highly oxidized. This makes them red (like rust).

4. How fast (in mm per year) are soils understood to build under ideal conditions?

Under the best circumstances, topsoil accumulates at about 1 mm per year.

Section 10.2

1. What are four kinds of erosion?

Wind, sheet, rill, and gully erosion.

2. How can excessive fertilizer and irrigation be a problem?

Excess fertilizer runs off into streams, rivers, lakes and oceans creating algal blooms and dead zones. Excess irrigation wastes water and can result in soil waterlogging and salinization.

3. What are some strategies for reducing soil erosion?

Contour plowing, terracing, planting cover crops, conservation tillage, and leaving ground cover and mulch on the soil can all reduce erosion.

Section 10.3

1. What is the difference between biocides, herbicides, insecticides, and fungicides?

Biocides kill all living things; herbicides kill plants; insecticides kill insects; fungicides kill fungi.

2. Why was DDT considered a “magic bullet”? Why was it listed among the “dirty dozen” persistent organic pollutants (POPs)?

DDT is highly effective against a wide variety of insect pests. It’s cheap, long-lasting, and has low human toxicity in the short term. However, it kills many non-target species and accumulates in food webs to reach toxic concentrations in higher trophic levels because it is persistent (stable, slow to break down). The “dirty dozen” POPs are serious problems because they last a long time in the environment and they are poisonous to many different organisms. It’s clear now that DDT was responsible for near-extinction of species such as the bald eagle, brown pelican, and osprey.

3. Name several of our dominant pesticides

Four of our dominant pesticides are Glyphosate, Atrazine, Metam sodium, Metolachlor S, and Acetochlor (fig. 10.19).

Section 10.4

1. List several arguments for and against sustainable farming.

Sustainable or organic farming can reduce pesticide exposure protecting both people and wildlife. In general soils stay healthier with these strategies than with chemical-intensive monoculture cropping, and energy use can be lower as well. Farmers report better health and greater satisfaction than their conventional neighbors. However, yields can be lower and labor costs higher with organic production.

2. Why is it controversial that Walmart is the largest seller of organic products?

The fact that Walmart has become the top seller of organic products in the United States has done much to move organic products into the mainstream. On the other hand, much of that organic food, comes from overseas, where oversight can be even more difficult than it is within the United States. Walmart needs huge quantities of material and tends to buy from the largest industrial-scale producers, which can squeeze out smaller, more environmentally sustainable farming operations.

3. What is IPM, and how is it used in pest control?

Integrated pest management (IPM) is a flexible, ecologically based strategy that is applied at specific times and aimed at specific crops and pests. It often uses mechanical cultivation and techniques such as vacuuming bugs off crops as an alternative to chemical application. IPM doesn’t give up chemical pest controls entirely but instead tries to use minimal amounts, only as a last resort, and avoids broad-spectrum, ecologically disruptive products. IPM relies on preventive practices that encourage growth and diversity of beneficial organisms and enhance plant defenses and vigor. Successful IPM requires careful monitoring of pest populations to determine economic thresholds, the point at which potential economic damage justifies pest-control expenditures, and the precise time, type, and method of pesticide application.

Chapter 11

Section 11.1

1. Which group in table 11.1 has the most known species? Which has the highest proportion of endangered species?

The highest number of known species is 1 million insects (although this is certainly a low estimate of the actual number). The highest percentage of endangered species is among amphibians. Frogs are threatened worldwide, for example.

2. What are the criteria for defining a biodiversity hot spot?

Hot spots, as defined by Myers, Mittermeir, and others, have at least 1,500 endemic species and have lost at least 70 percent of their habitat.

3. Describe four benefits we obtain from biodiversity.

We benefit from biodiversity because wild species provide new food crops or medicines as well as genetic traits that can be useful in a variety of ways. Biodiversity also provides ecological services, such as clean air, water, food, fiber, and waste recycling and it furnishes many aesthetic and cultural benefits.

Section 11.2

1. How do current rates of extinction compare to historic rates?

In undisturbed ecosystems, the rate of extinction appears to be around one species lost per decade. We are accelerating that rate by hundreds or thousands of times.

2. Explain HIPPO and its meaning for conserving biodiversity.

HIPPO, is an acronym for Habitat destruction, Invasive species introduction, Pollution, Population growth (of humans), and Overharvesting. Of these, habitat loss is the greatest threat to most species, but, depending on the species and conditions, the other factors also can be important.

3. Why are islands especially sensitive to invasive species?

Islands are particularly vulnerable to invasive species because they often have endemic species (those occurring nowhere else) that have evolved in the absence of predators and diseases. Furthermore, populations on islands are typically smaller, and thus they are more likely to fall below minimum viable population sizes when losses occur. Islands far from mainlands have lower immigration rates to replace individuals or species that are lost.

Section 11.3

1. Define endangered species and threatened species. Give an example of each.

Endangered species are those considered to be in imminent danger of extinction. Some examples include whooping cranes, California condors, and the Florida panther.

Threatened species are those that are likely to become endangered—at least locally—in the foreseeable future. Some examples include the Red wolf, grizzly bear, and polar bears.

2. Why are keystone, indicator, umbrella, and flagship species important?

Keystone species are those whose elimination would affect many other members of the biological community.

Indicator species are particularly sensitive to pollution or environmental change.

Umbrella species require large areas of habitat, the saving of which benefits many other species.

Flagship species are especially interesting or attractive and can motivate the public to preserve biodiversity and habitat generally.

3. What is gap analysis, and how is it related to ecosystem management and design of nature preserves?

Gap analysis involves looking for unprotected landscapes that are rich in species. This can help set priorities for preservation and human use.

Section 11.4

1. How many southern white rhinos are there now compared to a century ago?

There are at least 17,000 southern white rhinos today compared to a century ago when they were considered close to extinction.

2. Why aren’t zoos a good place to preserve whales, bats, and some reptiles?

Keeping small, isolated populations in zoos leads to inbreeding and genetic problems. And zoos can’t possibly preserve a very large sample of biodiversity due to their limited size and resources. Some species, such as bats, don’t reproduce well in captivity, and large animals, such as whales, need much more space than zoos can provide.

3. Describe two examples of successful captive breeding programs.

The Nene goose, black-footed ferrets, California condors, and white rhinos are examples of successful captive breeding programs.

Chapter 12

Section 12.1

1. What do we mean by closed-canopy forest and primary forest?

A closed canopy forest is one in which the crowns of the trees touch to cover most of the ground. A primary forest is defined as one “composed primarily of native species in which there are no clearly visible indications of human activity and ecological processes are not significantly disturbed”

2. Which commodity is used most heavily in industrial economies: steel, plastic, or wood?

Wood (including paper and other forest products) plays a part in more activities of the modern

economy than any other commodity.

3. What is a debt-for-nature swap?

In a debt for nature swap, a conservation organization buys national debt obligation (usually at a steep discount) from banks, governments, or lending institutions in exchange for a promise to protect and preserve nature.

Section 12.2

1. Are pastures and rangelands always damaged by grazing animals?

No, rotational or intensive grazing can be beneficial in certain situations. Excessive, prolonged grazing does cause serious damage to pastures and rangelands worldwide.

2. What are some results of overgrazing?

Overgrazing can reduce biodiversity and result in soil erosion, as plants die from overgrazing and rainfall and animal trampling lead to erosion of unprotected soil.

3. What is rotational grazing, and how does it mimic natural processes?

Rotational grazing means moving animals between paddocks on a regular basis to control what animals eat.

Section 12.3

1. How do the size and design of nature preserves influence their effectiveness? What do landscape ecologists mean by core habitat and edge effects?

Larger areas are better for many organisms, especially if the design protects a maximum amount of core habitat.

2. What is ecotourism, and why is it important?

Ecotourism means travel that is ecologically and culturally sustainable.

3. What is a biosphere reserve, and how does it differ from a wilderness area or wildlife preserve?

Generally, a biosphere reserve allows for some human activities and even residence. It explicitly plans for scientific research and adaptive management.

Chapter 13

Section 13.1

1. Define restoration (strict and broad sense), rehabilitation, intervention, reallocation, remediation, reclamation, re-creation, and mitigation.

Table 13.1 has all these definitions.

2. Describe five common components of restoration projects.

Removing physical stressors, controlling invasive species, replanting vegetation, captive breeding and reestablilshing fauna, and monitoring results.

3. What species was the main restoration focus on Nonsuch Island in Bermuda?

The Bermuda cahow or hook-billed petrel.

Section 13.2

1. What is a prescribed fire?

A prescribed fire is deliberately set to remove invasive species, to reduce excess flammable material, or to suppress growth of trees and brush.

2. What are oak savannas, and why are they difficult to restore?

Oak savannas are composed of scattered oak trees (or groves) surrounded by grass and forbs (flowering plants). Oaks have thick bark that makes them fire tolerant, but they may not compete well against other fast-growing trees. Oaks survive periodic low-intensity fires kill other trees and shrubs and keep clearings open, maintaining the open savanna environment.

3. Why are giant sequoias now threatened by fire?

70 years of fire suppression has allowed highly flammable species, such as firs and spruce to grow up around the giant sequoias. This allows ground fires to climb up into the sequoia crowns and burn the giant trees.

Section 13.3

1. Why are fires essential for prairies?

Periodic fires remove trees and brush and encourage the growth of grasses

2. What is the buffalo commons?

It has been suggested that because much of the Great Plains is too dry for much farming, and because its population has been declining for decades, a good use of the land would be to establish a large area free of fences or human habitation and in which the prairie ecosystem—complete with bison and other native fauna—could be restored.

3. Why are bison beneficial for prairies?

Bison travel in dense herds, eating everything in a given area and then moving on. This intense grazing removes invasive species and breaks up the sod, allowing growth of native annuals. The bison also fertilize the soil with their droppings and help recycle nutrients.

Section 13.4

1. Why do the Iraqi marshes, Gulf of Mexico wetlands, and the American Everglades need restoration?

In all these cases, restoration of native vegetation, fauna, and water systems would be beneficial for human communities, for flood and storm protection, for food production, and other benefits. Iraq’s marshes were starved of water by Saddam Hussein for political purposes. The Gulf of Mexico coastal wetlands have been starved of sediment by dikes and channelization of the Mississippi River. The Everglades have been dried by water diversion projects and polluted by agriculture (mainly sugar plantations).

2. What is wetland mitigation?

Mitigation means replacing a damaged wetland with a substitute wetland.

3. What is bioremediation?

Bioremediation is using living organisms, usually plants or bacteria, to take up, or break down, pollutants in soil or water. This can be an inexpensive and effective way to neutralize or remove pollutants.

Chapter 14

Section 14.1

1. Describe the layered structure of the earth.

The core, or interior, is composed of a dense, intensely hot mass of metal—mostly iron— thousands of kilometers in diameter. Surrounding the molten outer core is a hot, pliable layer of rock called the mantle. The mantle is much less dense than the core, because it contains a higher concentration of lighter elements, such as oxygen, silicon, and magnesium. The outermost layer of the earth is the lightweight, brittle crust.

2. Why are there many volcanoes and earthquakes along the “ring of fire” that rims the Pacific Ocean?

Trenches and volcanic mountains ring the Pacific Ocean rim from Indonesia to Japan to Alaska and down the west coast of the Americas, forming a “ring of fire” where oceanic plates are being subducted under the continental plates. At these margins, melting lava and pressure produce volcanoes and earthquakes (see fig. 14.4). This ring of plate margins surrounding the Pacific have more earthquakes and volcanic activity than any other region on the earth.

3. Describe the processes that produce the three rock types in the rock cycle.

Rocks are crushed, folded, melted, and recrystallized to produce new minerals in metamorphic rocks. Heat and pressure melt and recrystallize other material to create igneous rock. Other rock types erode, producing sediment (such as sand, silt, clay, or organic marine debris) that deposits, accumulates, and eventually solidifies into sedimentary rocks.

Section 14.2

1. Why are rare earth metals important, and why are we concerned about supplies?

Rare earth metals are used in a wide variety of technologies, including cell phones, electric motors, satellites, cameras, and computers. They are widely distributed in the earth’s crust, but only a few places have high enough concentrations for economical mining, in part because extracting the minerals can devastate land and water resources. China currently produces about 97% of all rare earth metals, and has used this leverage for economic advantage in the past.

2. What are the origins of coal and oil?

Coal derives from leaves and other plant material that accumulated in the bed of ancient swamps. Over millions of years and under immense heat and pressure, this carbon material turns into coal. Oil, in contrast, derives from the remains of tiny plankton and algae that once grew in the ocean. Buried in sediments, these materials undergo a metamorphous similar to that of coal.

3. Identify several reasons for recycling metals.

Recycling metals saves money and energy, avoids burying more materials in landfills, spares the environmental and social effects of mining, smelting, and distributing new metal, and helps finance the recycling of other, less valuable, materials.

Section 14.3

1. Why is sulfuric acid common in mine runoff?

Mineral deposits often contain high sulfur levels. When the sulfur is exposed to oxygen and water, it turns to sulfuric acid, which runs off in rain and groundwater.

2. Describe smelting and some of its environmental effects.

Smelting—roasting ore to release metals—is a major source of air pollution. The release of sulfuric acid from copper smelters in Ducktown, TN and Sudbury, Ontario, for example, killed all surface vegetation over a wide area. They also release heavy metals and other toxic substances. The smelters in Norlisk, Sibera have made that city one of the world’s most dangerous places to live.

3. Why might restoration be hard after mountaintop removal?

Once the top of a mountain has been gouged off and pushed down into the valley below, it would be extremely difficult and expensive to scrape it back up and replace it. Most of the debris is waste rock. It would take centuries to rebuild enough soil to support vegetation. Restoring the buried valleys would be equally difficult.

Section 14.4

1. What are the main reasons for mortality with earthquakes?

Most earthquake deaths are caused by collapsing buildings.

2. Describe different types of volcanic emissions and their effects.

Volcanoes eject gas and ash, as well as lava. The gases can be both intensely hot and toxic. They can flow down the mountain at more than 100 km/hr, and can be extremely deadly. Sulfur emissions from volcanic eruptions combine with rain and atmospheric moisture to produce sulfuric acid. The resulting droplets of H2SO4 interfere with solar radiation and can significantly

cool the world climate. Lava burns and buries everything in its path. Ash can bury cities and forests and fill rivers and lakes.

3. Is it a good idea to build on barrier islands? Why or why not?

Although people like to live directly on the beach where they can swim and enjoy the ocean view, barrier islands are more exposed to violent winds and storm surges than inland areas. Buildings are often destroyed while beaches and even whole islands can be washed away by waves and strong currents.

Chapter 15

Section 15.1

1. Describe the troposphere and stratosphere.

The layer of air immediately adjacent to the earth’s surface is called the troposphere (tropein means to “turn” or “change” in Greek). The stratosphere extends from the tropopause up to about 50 km (31 mi). This layer is vastly more dilute than the troposphere, but it has similar composition—except that it has almost no water vapor and nearly 1,000 times more ozone (O3).

2. What is albedo, and why is it important?

Albedo is reflectivity. Bright surfaces, such as snow and ice appear have a high albedo because they reflect light as well as other forms of radiative energy. Surfaces that absorb energy have a low albedo and generally appear dark. Black soil, pavement, and open water, for example, have low albedos. Absorbed energy heats the absorbing surface. This allows sunlight to heat the earth’s surface. Energy absorption or reflection is an important factor in determining the earth’s temperature.

3. Explain the idea of a greenhouse gas, and list four of them.

Most solar energy comes in short wavelengths that we perceive as light. These pass relatively easily through the atmosphere to the earth’s surface, where much of it is absorbed. Energy re-released from the earth’s warmed surface is longer-wavelength radiation. Gases in the atmosphere, especially carbon dioxide and water vapor, absorb much of this long-wavelength

energy and re-release it in the lower atmosphere. Thus the atmosphere is transparent to light wavelengths but retains infrared wavelengths, rather as a greenhouse allows light to pass through the glass but retains much of the heat from that energy. Re-irradiated heat energy doesn’t pass easily through the glass, so the interior of the greenhouse heats up. Water vapor, carbon dioxide, methane and nitrous oxide are the most important greenhouse gases.

4. What is latent heat?

The energy stored in evaporated water (that is, in water vapor) is called latent heat. Each gram of water vapor contains 540 calories of energy absorbed in the process of changing from liquid to vapor. That heat is released when water condenses again. This release of heat is an important driver of weather and climate processes.

Section 15.2

1. Why does it rain?

When air rises (for example in convection currents) it cools because of declining air pressure. Cooling causes moisture to condense. Condensing moisture can produce clouds, fog, rain, or snow.

2. What is the Coriolis effect, and how might it cause trade winds?

An air mass moves with the speed and direction with which it left the earth’s surface. Because the earth has a larger circumference at lower latitudes than near the poles, the surface has a higher velocity at lower latitudes. An air mass moving above the surface of the earth ends up travelling faster or slower than the surface below it. The effect of this difference is to make winds appear (from a point on the earth’s surface) to bend to the right (clockwise) in the northern hemisphere or left (counterclockwise) in the southern hemisphere. Trade winds follow this rule: for example, south-moving air masses in Europe “bend” right with respect to the earth’s surface, producing a pattern of winds moving from southern Europe toward the Americas.

3. Describe a monsoon, a cold front, and a warm front.

The most regular seasonal rains are known as monsoons. In India and Bangladesh, for example, monsoon rains come when seasonal winds blow hot, humid air from the Indian Ocean. The hot land surface produces strong rising convection currents that lift this air, causing heavy rain across the subcontinent. The boundary between two air masses of different temperature and density is called a front. When cooler air advances and replaces warmer air, we call the moving boundary a cold front. When warm air advances, we call it a warm front.

4. What is a cyclonic storm?

Storms that swirl in a direction dictated by the Coriolis effect (clockwise in the Northern Hemisphere, counterclockwise in the South) and are called cyclonic storms.

Section 15.3

1. What are three causes of Milankovitch cycles?

Milankovitch cycles are periodic shifts in the earth’s orbit and tilt, which change the distribution and intensity of sunlight reaching the earth’s surface. The three causes of these shifts are orbital eccentricity, variation in the tilt of the earth’s axis, and axial wobble.

2. How might past temperatures be reconstructed from ice cores?

Every time it snows, small amounts of air are trapped in the snow layers. In Greenland, Antarctica, and other places where cold is persistent, snow accumulates and compresses over centuries, slowly turning to ice. New layers compress lower layers into ice, but tiny air bubbles remain, even thousands of meters deep into glacial ice. Each bubble is a tiny sample of the atmosphere at the time that snow fell. Isotopes of oxygen in those bubbles indicate temperatures, because heavier isotopes (18O) are more likely to evaporate in warm years than in cold years. The ratio of 18O to the normal isotope 16O indicates temperature.

3. How do ocean and atmosphere interact in El Niño cycles?

In most years, steady equatorial trade winds push ocean surface currents westward, holding this warm pool in the western Pacific, where it drives warm, moist atmospheric convection cells and produces abundant rainfall. In El Nino years, this current weakens, and the warm ocean conditions, and heavy rainfall, shift back eastward toward the Americas. In these years, rainfall is greater in the Americas and weaker in Indonesia and Australia.

Section 15.4

1. Approximately how much has atmospheric CO2 changed since 1959?

From 315 ppm to about 400 ppm.

2. List four important greenhouse gases, and identify major sources.

(see fig. 15.19) CO2 from fossil fuel use, deforestation, and decay; CH4 from agriculture, waste, and energy production; N2O from agriculture; and fluorine-containing gases from refrigerants and industrial uses.

3. How do we know recent climate change is human-caused?

Our best evidence is climate modeling, which compares observed trends to climate models run with human inputs and without human inputs. Models with human inputs agree best with observed temperature and other climate patterns.

Section 15.5

1. Why might drought be associated with climate warming?

Shifts in convection cells and in patterns of weather movement, resulting from increased energy in the atmosphere, are likely to move low-pressure rainy conditions away from places we have expected to see them, or to increase high-pressure, dry conditions in some areas. Some areas will be wetter with climate change, but some will be drier. In particular, areas already dry will become drier, leading to droughts (see fig. 15.25).

2. List five to ten effects of changing climate.

Disappearing sea ice and mountain glaciers, rising sea levels, water shortages, plants and animals breeding earlier or changing their ranges, coral reefs bleaching, acidification of sea water, stronger storms.

3. List several reasons for public disputes over climate evidence.

Change is threatening, so we avoid accepting it; it’s easy to ignore large, long-term changes; there is a lack of understanding of evidence among the public; there is abundant funding for politicians and media who sow doubt climate change in order to prevent policy changes (fig. 15.27); media like to present stories in terms of debates but lack time to include evidence.

Section 15.6

1. What was the main benchmark of the Kyoto Protocol?

The most celebrated global agreement on controlling climate change has been the Kyoto Protocol, which followed a 1997 meeting in Kyoto, Japan. This agreement called for countries to voluntarily set their own targets for reducing emissions of CO2, CH4, and N2O, and fluorine gases. Most countries set targets of 5 to 10 percent below 1990 emissions, to be achieved by 2012.

2. List seven climate “wedges”.

Any of the wedges listed in table 15.3 would be good answers. The first seven identified by Pacala and Socolow were increasing fuel economy in our cars from 30 to 60 mpg, reduced reliance on cars (with cut driving from an average 10,000 miles to 5,000 miles per year), better insulation and efficient appliances in our houses and office buildings, increased efficiency in coal power plants, capturing and storing carbon at power plants, improving plant operation, and slashing reliance on coal.

3. Which is expected to cost more, controlling climate change or adapting to it?

Adapting to climate change is expected to cost far more than reducing climate change now.

Chapter 16

Section 16.1

1. Define primary air pollutants and secondary air pollutants.

Primary pollutants are those released directly from the source into the air in a harmful form (fig. 16.3). Secondary pollutants are converted to a hazardous form after they enter the air or are formed by chemical reactions as components of the air mix and react.

2. What are the six criteria pollutants in the original Clean Air Act? Why were they chosen?

Suspended particulate materials, sulfur oxides, carbon monoxide, nitrogen oxides , ozone, and lead were the first six criteria pollutants. They were chosen because they were considered the most serious threat to human health.

3. List several additional hazardous air toxins that are regulated.

Mercury, carbon dioxide, halogens, and a variety of organic compounds, such as gasoline vapors, solvents, and plastic components are also regulated now.

Section 16.2

1. What is an atmospheric temperature inversion, and why is it a problem?

Inversions occur when a stable layer of warmer air lies above cooler air. This condition is very stable, so air stays still. Air pollution remains in place, close to the ground where people breathe it, because there are no winds or convection currents to disperse it.

2. What is the difference between ambient and stratospheric ozone? What is destroying stratospheric ozone?

Ambient ozone is near the ground, in our surrounding environment. Stratospheric ozone is in the stratosphere. Ozone is a highly reactive molecule, so it is corrosive to living tissues. In the stratosphere, however, ozone is beneficial because it blocks incoming ultraviolet (UV) radiation. Chlorofluorocarbons and other halogen gases (such as bromine compounds) are destroying the stratospheric ozone layer especially over Antarctica.

3. What did the Montreal Protocol aim to accomplish?

The Montreal Protocol phased out most use of CFCs by 2000. As an unintended benefit, the protocol reduced the rate of climate change, since these compounds are powerful greenhouse gases.

Section 16.3

1. List several illnesses that are made worse by dirty air.

Fine particulates have been linked with heart attacks, asthma, bronchitis, lung cancer, immune suppression, and abnormal fetal development, among other health problems.

2. Explain the idea of “synergistic effects.”

Synergistic effects in which the injury caused by exposure to two factors together is more than the sum of exposure to each factor individually.

3. What is acid deposition? Identify two of the pollutants that cause it.

Acid deposition is precipitation of wet acidic solutions or dry acidic particles from the air. The main sources are airborne sulfuric acid (from sulfur dioxide) and nitric acid (from nitrogen oxides). These derive from combustion of fuels, especially coal in coal-powered electric generating plants.

Section 16.4

1. How are sulfur and particulate matter removed from effluent?

Particulate removal involves filtering air emissions. Filters trap particulates in a mesh of cotton

cloth, spun glass fibers, or asbestos-cellulose. Sulfur emissions can be reduced by switching to low-sulfur fuels. Cleaning fuels is an alternative to switching. Coal can be crushed, washed, and gasified to remove sulfur and metals before combustion. Alternatively, sulfur can be removed after combustion by spraying dry or wet limestone slurry (calcium carbonate) into the effluent gas stream.

2. What is the ratio of direct costs and benefits of the Clean Air Act? What costs are mainly saved?

The EPA found that the direct benefits of air quality protection by 2020 will be $2 trillion, while the direct costs of implementing those protections was about one-thirtieth of that, or $65 billion. The direct benefits were mainly in prevented costs of premature illness, death, and work losses. About half of the direct costs were improvements in cars and trucks, which now burn more cleanly and efficiently than they did in the past.

3. Which conventional pollutants have decreased most and least?

The greatest reduction in criteria pollutants has been in particulate materials and volatile organic compounds. The least improvement has been in nitrogen oxides.

4. What are some sources of air pollution in developing areas?

The largest sources of pollution in the developing world are coal-burning power plants, vehicle traffic, and un-regulated industry.

Chapter 17

Section 17.1

1. What is the hydrologic cycle, and how does it redistribute water around the globe?

The hydrologic cycle is the movement of water from the oceans, through the atmosphere, onto the surface as rain or snow, through the soil as groundwater, and across the surface back to the oceans in rivers and streams.

2. What percentage of water on the planet is fresh (nonsalty)?

2.4%

3. What is an aquifer, and how is it recharged?

An aquifer is a body of water held in the ground by impervious rock layers. It is recharged by surface water percolating through permeable or fractured rock layers; we call areas where this happens recharge zones.

Section 17.2

1. Define water scarcity and water stress.

Water scarcity occurs when the demand for water exceeds the available amount or when poor

quality restricts its use. Water stress occurs when renewable water supplies are inadequate to satisfy essential human or ecosystem needs, bringing about increased competition among potential demands.

2. What is drip irrigation, and why is it beneficial?

Drip irrigation applies water in tiny amounts just to the roots of the plants you want to cultivate. It is beneficial because it uses water efficiently and doesn’t encourage growth of weeds.

3. What percentage of all water withdrawals are for agricultural uses?

Worldwide, agriculture claims about 70 percent of total water withdrawal, and that use is increasing rapidly. Agricultural use ranges from 93 percent of all water withdrawn in India to only 4 percent in Kuwait, which cannot afford to spend its limited water on crops.

Section 17.3

1. What percentage of the world population could be experiencing water shortages and water stress by 2025?

According to the United Nations, 2/3 of all humans could be living in water-stressed countries by 2015.

2. Describe some effects of dams and diversion projects.

Dams and diversion projects allow us to store water during dry seasons and to live and grow crops in desert areas that otherwise wouldn’t be suitable for agriculture or human habitation. On the other hand, dams displace people and natural ecosystems, often have high evaporation rates. They collect sediment, which starves beaches and riparian habitat downstream. Dams can also increase landslides and earthquakes.

3. How might climate change affect our water supplies?

Some areas will become wetter with climate change, but many will get drier, especially areas that rely on winter snow accumulation for spring and summer water supplies. Melting of glaciers that provide a relatively stable water supply for about half the earth’s population will cause water shortages and water stress. More powerful storms will cause surface water to run off faster, and may, ironically, cause water shortages.

Section 17.4

1. How have farmers in California’s Klamath River basin reduced their water use?

During dry periods, farmers have fallowed fields or planted crops that require less water. They may grow high-value crops on just part of their land, and they can use more efficient methods of irrigation to save water.

2. Describe some examples of domestic water conservation.

We can conserve water by installing efficient appliances, recycling water (using gray water for

watering plants, for example), using xeriscaping (dry-land landscaping), taking shorter showers, flushing less often, avoiding letting the faucet run while washing dishes or brushing your teeth.

3. Give an example in which water policies and prices have encouraged conservation.

Charging the actual cost of storing and delivering water can encourage conservation. Requiring conservation measures can discourage waste. Treating water as a precious and finite resource can change our attitudes about how we use it. Restricting development in areas where there isn’t an adequate water supply can also help avoid crises.

Chapter 18

Section 18.1

1. Why was the Cuyahoga River historically important?

Photos of the river burning caught the attention of the public and helped dramatize the problem of water pollution. This helped push the passage of the Clean Water Act.

2. List eight major categories of water pollutants and give an example for each category.

Table 18.1 lists eight categories of water pollutants and gives both an example and a source for each. Categories are infectious agents, organic chemicals, inorganic chemicals, radioactive materials, sediment, nutrients, oxygen-demanding waste, and thermal pollution.

Section 18.2

1. Why is the definition of navigable water important?

The Clean Water Act applies only to navigable waters, which fall under federal jurisdiction, so determining what is navigable determines where the Clean Water Act applies.

2. Which countries have had the greatest success in providing safe water to their citizens?

Wealthy industrialized countries in Europe, North America and elsewhere generally have the safest public water supplies.

3. What geographic region lacks safe water for the greatest remaining proportion of its population?

Water quality issues persist in many developing countries, but sub-Saharan Africa probably has the highest percentage of its population that lack access to clean, safe drinking water.

Section 18.3

1. Describe the process of municipal sewage treatment.

Primary treatment includes screening and settlement to remove solids. Secondary treatment involves biological degradation (usually by bacteria) of dissolved organic materials in a filter

bed, aeration tank, or sewage lagoon. Tertiary treatment removes plant nutrients (nitrogen and phosphorus).

2. What is a constructed wetland?

A constructed wetland is an artificial marsh or lagoon in which sunlight, aeration, and living organisms clean water.

3. How does bioremediation clean water?

Bioremediation involves treatment with plants or microorganisms that absorb or degrade pollutants.

Section 18.4

1. Identify five important examples of water quality legislation.

This question can be answered with any five of the nine important acts listed in table 18.2 on p 421.

2. What is best practicable control technology?

This term describes legal standards for controlling water pollution, along with discharge permits for pollution sources. The term refers to the best technology for pollution control available at reasonable cost and operable under normal conditions (see Glossary).

Chapter 19

Section 19.1

1. What happened in Mayflower, Arkansas, in 2013, and why is it important?

An oil spill from a pipeline carrying tar sands crude shows how difficult it is to contain this material, which is highly acidic and is pumped under high heat and pressure. The event also showed how difficult it is to clean it up when a spill occurs. This is a warning about the potential dangers of the Keystone XL pipeline and other pipelines carrying oil from tar sands.

2. What are the major sources of commercial energy worldwide and in the United States?

The major sources of energy worldwide and in the U. S. are coal, oil, and natural gas with a small amount of nuclear power and even smaller amounts of solar, wind, hydro and biomass power. However, renewable sources are large enough to supply all the energy we need if we develop them.

3. How does energy use in the United States compare with that in other countries?

Most European countries use far less energy per person than the U.S. does. Less developed countries use far less energy per person than we do. In some cases 80 or 100 times less. The only

countries that use more energy per person are the oil rich nations of the middle east.

Section 19.2

1. Where are the largest coal deposits located?

The largest coal deposits in the world are in the United States, China, and Russia.

2. What are the greatest disadvantages of burning coal?

The biggest problems with coal are release of CO2, SO2, NOx, heavy metals, and other pollutants when it’s burned. Underground mining is dangerous, and surface mining destroys enormous land areas.

3. What is carbon capture and how would it work?

Carbon capture entails removing CO2 from the effluent and storing it in porous rock layers or in salt-water aquifers. Schemes have been proposed for pumping CO2 into deep geological formations or into deep ocean trenches. Some rock types will also bind CO2 over time. Biological storage is another option. Billions of trees or other green plants could be planted to absorb the CO2 we generate. Or effluent gasses could be bubbled through algae cultures.

Section 19.3

1, How have our views about the size of world oil resources changed in the past few decades?

Not long ago, we were worried about “peak oil” and the prospects that we’d run out. Recently we have sharply increased supplies of oil produced by directional drilling and fracking. The question now is how much of that oil can we afford to extract and burn given the threat of climate change?

2. What is ultradeep oil drilling, and why is it risky?

Ultradeep drilling is drilling in very deep water, such as beyond the continental shelf in the Gulf of Mexico. Wells in more than about a mile of water depth (1.6 km), or by some definitions, more than 3 km deep. This drilling is risky because the temperatures and pressures at those depths can destroy drilling equipment and pipelines, and it is difficult to repair damage or stop leaks under those conditions.

3. What are tar sands, and what problems are associated with their mining, processing, and shipping?

Tar sands are deposits of a semi-solid hydrocarbon called bitumen mixedwith sand and clay. It takes a ton of tar sand and large quantities of fuel and water to extract a barrel of crude oil. This leaves huge open pit mines where the sand is dug up, vast lakes of polluted water, and produces an inordinate amount of greenhouse gases. It takes 2 to 4 barrels of water for each barrel of oil produced, and disposal of contaminated wastewater is a serious problem at processing sites. Life-cycle analysis of energy costs shows that tar sands produce about 20 percent more CO2 per

unit of energy delivered than conventional oil.

Section 19.4

1. What is fracking, and what problems does it cause?

Fracking (also knowns as hydrofracking or hydraulic fracturing) involves pumping a slurry of sand and chemicals down a well at very high pressure to fracture the rocks and allow oil or gas to flow to the surface. Fracking has vastly increased our supply of oil and gas, but it contaminates aquifers, releases methane (a powerful greenhouse gas) into the atmosphere, and may trigger earthquakes.

2. Where is the Marcellus Shale, and why is it important?

The Marcellus shale underlies the Appalachian Mountains from Virginia to New York. It could contain up to 346 trillion ft3 of natural gas and 62 billion barrels of petroleum.

3. What are methane hydrates, and why are they of concern?

Methane hydrates are small bubbles or individual molecules of natural gas trapped in a crystalline matrix of frozen water. At least 50 oceanic deposits and hundreds of land deposits are known. Altogether they are thought to hold some 10,000 gigatons (1013 tons) of carbon, or twice as much as the combined amount of all coal, oil, and conventional natural gas. But if even a portion of that methane escapes into the atmosphere in drilling or as deposits melt, it could cause a climate disaster.

Section 19.5

1. Draw and label a diagram of a typical PWR nuclear plant.

The drawing should look something like fig. 19.23 on p 441. It should include fuel rods and control rods in a reactor core; a primary and secondary water circulation loops, with a heat exchanger to transfer heat; a turbine and generator; and cooling water circulation.

2. How is energy released from uranium atoms?

When U 235, the radioactive isotope of Uranium is bombarded with neutrons, it transforms into the unstable isotope U236, which then splits (fissions) into tin and molybdenum, releasing heat and more neutrons. This can create a chain reaction that transforms mass into vast amounts of energy.

3. How are radioactive wastes from power plants currently being stored?

Because we don’t have a permanent waste repository, the nuclear waste from power plants is currently either being held in waste storage pools inside the power plants or in dry cask storage outside. Neither method was intended for permanent storage.

Chapter 20

Section 20.1

1. Report on five ways we could conserve energy individually or collectively.

We could reduce energy use by installing efficient lights, such as LED lamps, insulating and weather-stripping our homes, turning off appliance, walking, taking the bus, riding a bike, car-pooling, driving efficient cars, using stairs instead of elevators, turning thermostats down in the winter and up in the summer and a host of other actions (see “What Can You Do? p 454).

2. Explain the principle of net energy yield. Give some examples.

This is energy input divided by energy output. The net energy yield from a coal-fired power plant is about 30 to 35 percent. The net energy yield from cogeneration is about 80 to 90 percent.

3. What is cogeneration?

Cogeneration is the simultaneous production of both electricity and steam or hot water in the same plant.

Section 20.2

1. What is the difference between active and passive solar energy?

Passive solar systems collect energy without any moving parts to simply gather and hold heat in a mass such as stone, brick, or water.

Active solar systems generally pump a heat-absorbing, fluid medium (air, water, or an antifreeze solution) through a relatively small collector, rather than passively collecting heat in a stationary medium like masonry. Photovoltaic cells (see answer below) could also be considered active solar.

2. How do photovoltaic cells generate electricity?

When solar energy strikes a photovoltaic (PV) cell, an electron is dislodged from atoms in the p-layer in the silicon crystal. These electrons cross an electrostatic junction between different semiconductor materials. This creates a surplus of electrons in the n-layer and a shortage of electrons (or a positive charge) in the p-layer. The difference in charge creates an electric current in a circuit connecting the two layers.

3. What is smart metering, and how might it be beneficial?

A smart meter tells you how much electricity you’re using at any given moment and how much it costs. In systems where there’s time of day pricing, this can allow you to buy energy at the cheapest rates and save substantial amounts of money. It also lowers peak demand and makes it unnecessary for utilities to overbuild power generating facilities or use expensive, inefficient, peaking units.

Section 20.3

1. How much energy could we obtain from wind?

Using current technology, we could harvest more energy from wind than the total global commercial energy supply.

2. What regions of the United States have the strongest and most reliable wind?

The Great Plains, from North Dakota to the Texas Panhandle have the strongest and most reliable wind in the U.S.

3. What state currently has the greatest installed wind capacity?

Texas

Section 20.4

1. What is a fuel cell and how does it work?

A fuel cell produces electricity by stripping electrons from hydrogen atoms at an anode to produce hydrogen ions (protons) that migrate through a semipermeable electrolyte medium to the cathode, where they reunite with electrons from an external circuit and oxygen atoms to make water. Electrons flowing through the circuit connecting the electrodes create an electrical current.

2. How do we make biofuels out of plant material?

Biodiesel can be made directly from certain plant oils. Ethanol is made by converting starch or cellulose to sugar and then fermenting the sugar to alcohol. The alcohol is separated from other by-products by distillation.

3. Why might Miscanthus be a good source of ethanol?

Miscanthus grows rapidly, 3 or 4 meters in a single season. It needs little fertilizer and is resistant to most diseases and insects. It can produce at least five times as much dry biomass per hectare as corn. Making ethanol from cellulose is difficult, but it avoids using food (grains, sugar) for fuel.

Section 20.5

1. What are some advantages and disadvantages of large hydroelectric dams?

Hydroelectric dams provide abundant, carbon-free electricity, but the reservoirs they require often flood valuable farmland, historical sites, and towns and displace many people. They also can emit methane if vegetation isn’t removed before the land is flooded. In dry climates, dams can vast amounts of water to evaporation, and if dams burst, as many have, they release destructive floods.

2. How can geothermal energy be used for home heating?

Pumping water through deep wells, then concentrating and transferring heat with heat pumps can use the relatively constant temperature of the earth to heat homes in the winter or cool them in the summer.

3. Describe how tidal power or ocean wave power to generate electricity.

Wave power uses a floating mechanism that bobs up and down as waves pass. The motion is converted to electricity by a generator.

Chapter 21

Section 21.1

1. Why is e-waste difficult to dispose of properly?

e-waste is waste difficult to dispose of properly because it includes a wide variety of different and often toxic materials. Although it may have valuable metals, such as gold, they’re present in very small quantities mixed with many other materials.

2. How does a sanitary landfill differ from an open dump?

A modern sanitary landfill has a bottom liner of heavy, impervious plastic to prevent leakage. Garbage is covered every day to deter pests and prevent wind-blown trash. When filled, the landfill is covered with an impermeable cover and surrounding groundwater is monitored for leakage. Methane generated by organic material is drawn off and burned. An open dump doesn’t have any of these safeguards.

3. Why is it good to divert yard waste and organic material from the general waste stream?

Diverting yard waste and organic material from the general waste stream helps extend the life of landfills, decreases methane production from buried, decomposing organic material, and can produce valuable compost.

4. Why do many northern European countries incinerate much of their waste?

Many northern European countries incinerate much of their waste because they don’t have space for landfills and because there is valuable energy in trash. Pollution prevention rules also make incinerators a clean disposal method, although it is not as good as recycling waste. The high cost of landfilling makes incineration economically competitive in Europe.

Section 21.2

1. Describe some general trends in landfilling, recycling, and incineration of waste.

Landfills continue to dominate American waste disposal, but recycling (including composting) has quadrupled since 1980 (fig. 21.12). Recycling now accounts for about one-third of our waste stream; combustion with energy recovery make up about another 10 percent.

2. Why are plastics difficult to recycle?

Plastics are difficult to recycle because there are so many different types of plastics in use, and they are hard to separate and chemically incompatible. That is, mixing them together makes a product that’s unusable for most high-value applications.

3. What is demanufacturing, and why is it used for some types of waste?

Demanufacturing means disassembling a product carefully (not simply shredding, crushing, or melting) so individual materials can be separated and recovered. It allows recovery of small volumes of high-value materials and avoids some release of toxic materials.

Section 21.3

1. What is a legal definition of hazardous waste?

Legally, a hazardous waste is any discarded material, liquid or solid, that contains substances known to be (1) fatal to humans or laboratory animals in low doses, (2) toxic, carcinogenic, mutagenic, or teratogenic to humans or other life-forms, (3) ignitable with a flash point less than 60°C, (4) corrosive, or (5) explosive or highly reactive (undergoes violent chemical reactions either by itself or when mixed with other materials).

2. What are brownfields? Why are they both important and difficult to clean up?

Brownfields are unused or abandoned industrial sites, with soil or water contaminated with toxic and hazardous substances. It is difficult and expensive to remove toxic and hazardous materials once they are released in the environment, but remediation allows cities to rebuild on otherwise unusable, expensive-to-maintain, dangerous spaces.

3. How might hazardous wastes be converted to safer forms?

Some hazardous wastes can be safely incinerated or chemically processed to reduce their toxicity or hazardous characteristics.

4. What is bioremediation?

Bioremediation means using living organisms (plants, bacteria, or fungi, for example), to break down toxic materials to less harmful forms, or to concentrate toxic and hazardous materials so they can be safely removed from a site.

Chapter 22

Section 22.1

1. What proportion of the world’s population is now urban?

Worldwide, more than half the population lives in cities; in many regions more than 70 percent are urban.

2. List five of the largest 13 cities in 2011.

Tokyo, Japan, Delhi, India, Mexico City, Mexico, New York-Newark, USA, Shanghai, China (Table 22.2).

3. Give an example of how government policy can promote migration to cities.

Governments commonly spend much of their budgets on improving urban areas, especially

around the capital city where leaders live. This gives the major cities a virtual monopoly on new jobs, housing, education, and opportunities, all of which bring in rural people searching for a better life.

Section 22.2

1. Why are traffic congestion and water pollution problems in most fast-growing cities in developing countries?

Rapidly growing urban populations need infrastructure, such as roads, public transportation, water resources, and so on. Low-income cities often lack the tax base, or often the political organization, to pay for these services.

2. What are shantytowns, and why are they common?

Shantytowns are settlements created when people move onto undeveloped lands near cities and build houses there. Residents usually don’t own the land on which they live, and because the settlements are unplanned and not officially sanctioned, they often lack public services, such as water, sewers, and power.

3. List several costs of polluted air and water in cities.

Polluted air and water cause illnesses that decrease life expectancy, productivity, and quality of life. This decreases the GDP of a city as well as civic engagement and willingness to work on urban improvements.

Section 22.3

1. Describe urban sprawl, and explain some reasons for it.

Sprawl is the expansion of cities into low-density, expansive suburbs. The process is driven by residents’ needs for low-cost housing or space, by policies such as those that that promote inexpensive automobile transport or development of outlying areas.

2. Identify several costs associated with expansive urban growth.

Expansive growth requires great increases in infrastructure per capita. Infrastructure includes road and sewer networks, services such as snow removal, police, and fire services, new schools in outlying areas, and other costs, as well as reducing the use of inner-city infrastructure.

3. How did Curitiba, Brazil, make public transit work?

Curritiba made dedicated transit lanes, speeded passenger loading and unloading with enclosed bus shelters, and provided a network of express buses to suburbs.

Section 22.4

1. List several reasons for smart growth.

Smart growth makes living in neighborhoods more enjoyable. By planning a range of housing

styles and costs, smart growth allows people of all income levels, including young families and aging grandparents, to find housing they can afford. Open communication between planners and the community helps make urban expansion fair, predictable, and cost-effective. It also protects environmental quality by making pleasant spaces for us to live, and to preserving some accessible, natural spaces for all to enjoy. It strives to promote the safety, livability, and revitalization of existing urban and rural communities (see table 22.4).

2. Identify some priorities for green urbanism.

Green urbanism emphasizes redevelopment and in-fill development near urban centers, rather than greenfield development (which would be on former farmlands, for example). Walkable density, mixed commercial and residential uses, energy efficient housing, reduced car dependence, and integrated green space can all help reduce the environmental and climate costs of cities. Vauban demonstrates many of the priorities of green urbanism.

3. What are some benefits of clustering houses in a development?

By carefully clustering houses on smaller lots, a conservation subdivision can provide the same number of buildable lots as a conventional subdivision and still preserve 50 to 70 percent of the land as open space. This not only reduces development costs (less distance to build roads, telephone lines, sewers, power lines, and so on) but also helps foster a greater sense of community among new residents. Walking paths and recreation areas get people out of their houses to meet their neighbors. Home owners have smaller lots to care for, and yet everyone has an attractive view and a feeling of spaciousness.

Chapter 23

Section 23.1

1. Define nonrenewable, renewable, and intangible resources.

Nonrenewable resources are materials present in fixed amounts in the environment, especially earth resources such as minerals, metals, and fossil fuels. Renewable resources are things that can be replenished or replaced. These include living organisms, fresh water from rain and snow, and sunlight—our ultimate energy source. Intangible resources include amenities such as open space, beauty, and diversity.

2. What does it mean to externalize costs?

Costs are passed off to someone else. Producing electricity, for example, usually involves some pollution, and a power company allows the public to absorb the cost of that pollution in terms of health care or reduced crop production.

3. Why does neoclassical economics emphasize growth?

Constant economic growth is considered necessary and desirable, in the neoclassical view. Growth keeps people happy by always offering more income or goods than people had last year This is seen as the only way to maintain full employment and avoid class conflict arising from

inequitable distribution of wealth. Growth is also essential because businesses borrow resources to operate and grow. Few lenders are willing to share their money without a promise of greater returns later. Thus businesses must continue to expand in order to increase profits and maintain the confidence of shareholders, whose money they are using to run their operations.

Section 23.2

1. What is ecological about ecological economics?

Ecological economics tries to assign value to environmental resources and goods, which are usually excluded from the accounting for production costs. Normally the cost of ecosystem services and other environmental inputs, or degradation of them, are borne by the public or by the environment.

2. What are ecosystem services? Give several examples.

Ecosystem services is a general term for the resources provided and waste absorbed by our environment. These services are often grouped into four general classes (table 23.2): regulation (of climate, water supplies, and other factors), provision (of foods and other resources), supporting or preserving (of crop pollinators, nutrient cycling), and aesthetic or cultural benefits (fig. 23.11).

3. List several externalized costs of power production with coal.

These costs include health care, water pollution, damage from air pollution and acid deposition, production of an educated work force, public infrastructure, and other costs.

4. What is TEEB, and what are its aims?

A UN program called The Economics of Ecosystems and Biodiversity (TEEB), which has been working to improve estimates of the value of ecosystem services. TEEB studies have shown that preserving ecosystems is far more cost-effective than using up their resources.

Section 23.3

1. Describe Hubbert’s curve and its prediction about oil resources.

Hubbert’s curve predicted the peak and decline in oil resources. The economic theory has been that as oil becomes scarce, competition for it would rise, as would prices.

2. Explain the tragedy of the commons.

The tragedy of the commons is the idea that a shared common resource will be overused and destroyed because for each user, the benefits of increasing his or her own use outweigh the personal costs, which are borne by the community. This idea was promoted by Garret Hardin.

3. What is common property management?

Common property management is an alternative scenario to the tragedy of the commons: communities often establish agreed-upon oversight and management that maintain shared

resources over the long term. This idea has been emphasized by Elinor Ostrom and her colleagues.

4. How do the two “limits to growth” graphs (fig. 23.17) differ and why?

The second graph shows results of a model that assumes reduced birth rates and consumption rates, compared to the model shown in the first graph. As a consequence of these input assumptions, the first model showed overexploitation and collapse of resources; the second showed stabilization and persistence of resource use.

Section 23.4

1. What are GNP and GPI? How do the two differ?

Gross national product (GNP) accounts for goods and services; the genuine progress index (GPI) takes into account real per capita income, quality of life, distributional equity, natural resource depletion, environmental damage, and the value of unpaid labor.

2. List several factors accounted for by the HDI.

The United Nations Development Programme’s human development index (HDI) to track social progress. HDI incorporates life expectancy, educational attainment, and standard of living as critical measures of development.

3. What is the purpose of cost–benefit analysis?

Cost–benefit analysis (CBA) attempts to assign values to resources as well as to social and environmental effects of carrying out, or not carrying out, a given undertaking. It tries to find the optimal efficiency point at which the marginal cost of pollution control equals the marginal benefits (fig. 23.20).

Section 23.5

1. How did the cap-and-trade approach work to control sulfur?

Emission caps were set, and companies were left to find the cheapest way to meet the emissions cap. By trading permits and developing cheaper than expected pollution control technology, industry managed to reduce sulfur emissions much more cheaply than expected.

2. List some arguments for and against carbon trading.

In theory, carbon trading could find the cheapest way to reduce total emissions just as sulfur trading did. Making it more expensive to pollute should provide incentives to develop non-polluting technologies faster. However, carbon trading has been less effective than hoped in producing actual reductions in carbon. In part this has to do with the global scale of carbon trading. Critics argue that the scheme mainly benefits bankers and traders in the market.

Section 23.6

1. What is the definition and the purpose of NAFTA?

The North American Free Trade Association (NAFTA) removed trade taxes and regulations at borders between Mexico, the US, and Canada. As with other free trade agreements, the aim was to reduce costs of production and increase economic growth.

2. Why might microlending produce more widespread results than World Bank lending?

Microlending provides capital to a great number of entrepreneurs, each of whom is likely to use the money in local markets, increasing its effect for local people. Microlending also aids the very poor, who otherwise have few opportunities to increase wealth, whereas World Bank lending works with large banks and industries that already have wealth.

3. What does it mean that green business adopts ideas from ecology?

Green business considers the fact that in nature nothing is wasted, and one organism’s waste is another’s resource. Therefore green business tries to minimize waste and to plan for reuse of waste products. Like ecology, green business tries to consider the whole “’ecosystem,” so it emphasizes energy efficiency, providing sustainable livelihoods, and protecting diversity.

4. List several benefits and weaknesses of green consumerism.

Consumers can push producers to work in environmentally or socially sustainable ways, and directing money to sustainable producers can make it possible for them to continue good practices and make a living. On the other hand, identifying the best products can be ambiguous, as in the case of organic goods produced in China and sold at Walmart in the US.

Chapter 24

Section 24.1

1. What is the policy cycle, and how does it work?

The policy cycle is discussed in section 24.2 (see figure 24.8). This term emphasizes that policy evolves gradually as a problem is repeatedly revisited. The cycle involves identifying a problem, setting an agenda, developing proposals to solve the problem, building support, enacting rules or laws, implementing the policy, evaluating results, suggesting changes, and starting the cycle again by identify remaining problems.

2. What is the precautionary principle?

This principle says that when an activity threatens to harm health or the environment, we should fully understand risks before initiating that activity. According to this principle, for example, we shouldn’t mass-market new chemicals, new cars, or new children’s toys until we’re sure they are safe.

3. How did the 1969 Santa Barbara oil spill help pass environmental legislation?

The Santa Barbara oil spill generated a great deal of public attention to the problems of pollution and played an important role in passage of Environmental Laws in the 1970s. It was ideally

situated for TV. It was close enough to Los Angeles for TV crews to get film back in time for the five o’clock news; it was a picturesque section of the coast line. The cleanup featured large numbers of students and other volunteers working on beaches along with sad images of oil soaked birds and otters; and it played out over a long-enough time to generate public interest.

Section 24.2

1. Describe the major provisions of NEPA, the Clean Air Act, the Clean Water Act, the Endangered Species Act, and the Superfund Act.

NEPA authorizes the Council on Environmental Quality (CEQ), directs federal agencies to take environmental consequences into account in decision making, and requires an environmental impact statement (EIS) be published for every major federal project likely to have an important impact on environmental quality

The Clean Air Act requires the EPA to identify, monitor, and reduce air contaminants.

The Clean Water Act directs the EPA to identify and control point source pollutants, end-of-the-pipe discharges from factories, municipal sewage treatment plants, and other sources.

The Endangered Species Act authorizes the Fish and Wildlife Service to identify and list species that are vulnerable, threatened, or endangered. Once a species is listed as endangered, the ESA provides rules for protecting it and its habitat, and establishing a recovery plan.

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) addresses abandoned industrial sites, emergency spills, or uncontrolled contamination, and allows the EPA to try to establish liability, so that polluters help to pay for cleanup. The Superfund (by which the act is commonly known) originally taxed manufacturers to pay for this cleanup, although taxes on the public now pay for cleanup.

Section 24.3

1. Describe the path of a bill through Congress. When are riders and amendments attached?

Bills are introduced by members of Congress. They pass through appropriate committees where hearings are held and amendments can be added. If there’s sufficient support, the bill is moved to the floor of the House of Representatives or the Senate for further debate and amendments. If it passes both houses and is approved by a conference committee to resolve any differences between versions, and goes to the President for signature.

2. What is legal standing, and why is it important?

Legal standing is the right to appear in court and be heard on an issue. If the courts rule that you don’t have standing, you have no rights in a particular case and your interests and opinions have no bearing on the deliberations.

3. What regulatory agencies have major environmental oversight in the United States?

The EPA has the greatest responsibility for environmental issues in the U.S. The Department of the Interior and Department of Agriculture manage more land than any other branch of

government, as well as allowable activities on those lands. Fisheries and Wildlife regulate endangered species The Department of Labor oversees workplace safety, while the Food and Drug Administration is responsible for the purity and wholesomeness of food and drugs.

Section 24.4

1. Describe five important international environmental treaties.

Any of the ten international environmental treaties described in Table 24.2 on p 554 would be suitable answers for this question.

2. Why has most international environmental protection been based on an honor system?

The international community has been unwilling to create a global enforcement system to protect our common environment, so adherence to international accords often depends on national pride or embarrassment.

Section 24.5

1. What is community-based planning?

As the name implies, community-based planning uses local knowledge and involvement to establish policy.

2. What are green plans?

Green plans are comprehensive, long-range national strategies for environmental protection and sustainable resource use.

3. Describe Bolivia’s Law of Mother Earth.

Bolivia’s Law of Mother Earth treats the planet as a living being. It grants to all people equal rights to a clean environment, including safe water, protection of biodiversity, clean air, and essential ecological functions. It requires the government to transition toward renewable energy, to develop new economic indicators that account for environmental costs of economic activities, to focus on food sovereignty, and to invest in energy efficiency.

Chapter 25

Section 25.1

1. What is environmental literacy?

Environmental literacy involves fluency in the principles of ecology and a working knowledge of the basic grammar and underlying syntax of environmental wisdom. Environmental literacy aims to establish an ethic of stewardship.

2. Why are corporations interested in hiring people with environmental science training?

Environmental science training aids a wide variety of professions. Ecologists, chemists, and other scientists are needed to understand the natural world and the effects of human activity on the environment. Lawyers and other specialists are needed to develop government and industry policy, laws, and regulations to protect the environment. Engineers are needed to develop technologies and products to clean up pollution and to prevent its production in the first place. Economists, geographers, and social scientists are needed to evaluate the costs of pollution and resource depletion and to develop solutions that are socially, culturally, political

3. How can artists and writers, as well as chemists and biologists, work for environmental quality and environmental health?

Good communicators, artists, and especially journalists are needed to help the public understand environmental issues and policy matters. A liberal arts education will help you develop skills such as communication, critical thinking, balance, vision, flexibility, and caring that should serve you well. Employers need a wide variety of people; small companies need a few people who can do many things well.

Section 25.2

1. What is “affluenza”?

Affluenza is a drive to possess material goods regardless of its value or utility. The term suggests that this drive is unhealthy, like an illness.

2. Describe the benefits and challenges of green consumerism.

Consumers want sustainably or fairly produced products that protect both the environment and workers who create goods, but it is difficult to evaluate all the factors involved in production and marketing of goods.

3. Why is it important to vote?

Voting is an important way to participate in public policy forming and to ensure that we have responsive and responsible people in government.

4. What are some ways you can learn leadership, and why is this important?

Student organizations are an especially important place to learn leadership. You have peers who share your viewpoint, and who can help you plan. You have other peers who disagree but who can challenge you to debate and to sharpen your arguments. You can publish your arguments in student newspapers and explore them in classes. And all these experiences can help you work toward goals you care about—and even jobs you hope to get after you graduate.

Section 25.3

1. What are the strengths and weaknesses of national environmental organizations?

National organizations are influential and have the resources and knowledge to work with policy makers. They can also be complacent and protective of established practices. They can educate, organize, and influence the public, but they’re sometimes undemocratic, excessively professionalized, and inattentive to emerging issues.

2. What are some strategies of environmental organizations?

Environmental organizations seek to multiply the power of individual citizens by helping them work together. Some work for political change, others specialize in gathering and disseminating information, while still others undertake direct action to protect a specific resource.

3. Identify an international environmental NGO and its goals.

Try to draw from your experience or your reading of this book to identify one of the many international nongovernmental organizations working on environmental problems. One of these is Greenpeace, which draws public attention to problems by carrying out well-publicized confrontations with whalers, seal hunters, toxic waste dumpers, and others who threaten very specific and visible resources.

Section 25.4

1. Why are colleges and universities good places for exploring new strategies for sustainability?

Colleges and universities can be sources of information and experimentation in sustainable living. They have the knowledge and expertise and motivation to seek new methods and ideas. Students often have the energy and enthusiasm to do research, and they are motivated by the opportunity to learn about matters that are important to them.

2. What is fossil fuel divestment, and what are some arguments for and against it?

Divestment means selling shares of companies that have policies and activities that contradict your principles.

Opponents of divestment argue that it is essential to remain engaged, and to own shares in companies, in order to influence corporate practices. They also point out that most educational institutions invest in large, mixed funds, in which it is impossible to tell precisely where investment dollars lie. Unlike personal investments, which can be placed in socially responsible funds or indexes, the large funds of institutions cannot choose socially and environmentally responsible funds. Further, because the magnitude of educational institutions’ investments is minuscule compared to the size of the fossil fuel industry, divestment will do little practical harm to those companies. In addition, many colleges and universities are already on delicate ground financially. Risking lower returns is something many administrators are unwilling to do.

Proponents of divestment point out that educational institutions must be committed to the future well-being of their students. It seems hypocritical, they suggest, to be simultaneously educating students and undermining the future they will inhabit, as global climate change threatens cities, farmland, water supplies, public health, biodiversity, and ecosystem services by investing in fossil fuel industries that are emitting climate-changing greenhouse gases.

3. What are some strategies in the Campus Climate Challenge?

At many colleges and universities, students have undertaken campus audits to examine water and energy use, waste production and disposal, paper consumption, recycling, buying locally produced food, and many other examples of sustainable resource consumption. At more than 100 universities and colleges across America, graduating students have taken a pledge for social and environmental responsibility. Campuses often have building projects that can be models for sustainability research and development. Many campuses have invested in clean energy, set strict green building standards for new construction, purchased fuel-efficient vehicles, and adopted other policies to save energy and reduce their greenhouse gas emissions.

Section 25.5

1. List several goals or aspects of sustainability.

A demographic transition to a stable world population of low birth and death rates. An energy transition to high efficiency in production and use, coupled with increasing

reliance on renewable resources. A resource transition to reliance on nature’s “income” without depleting its “capital.” An economic transition to sustainable development and a broader sharing of its benefits. A political transition to global negotiation grounded in complementary interests between

North and South, East and West. An ethical or spiritual transition to attitudes that do not separate us from nature or each

other.

2. What is the source of the Millennium Development Goals?

The United Nations has developed this set of goals and objectives for sustainable development. The goals resulted from a global assessment process, in which more than 1,360 experts from around the world worked on technical reports about the conditions and trends of ecosystems, scenarios for the future, and possible responses.

3. Identify eight major areas in which quantifiable goals have been set for the Millennium Development Goals.

The goals are listed in table 25.5 on p 576:

Eradicate extreme poverty and hunger. Achieve universal primary education. Promote gender equality and empower women. Reduce child mortality. Improve maternal health. Combat HIV/AIDS, malaria, and other diseases. Ensure environmental sustainability. Develop a global partnership for development.