CH-1-2 Environmental Problems, Their Causes, and Sustainability – Sustaining the Earth : Chapter Notes

This Document Contains Chapters 1 to 2 Chapter 1 Environmental Problems, Their Causes, and Sustainability Summary and Objectives (Note: *This is a concept-centered book, with each major chapter section built around one or two key concepts derived from the natural or social sciences. Key questions and concepts are summarized at the beginning of each chapter. You can use this overview as a preview and as a review of the key ideas in each chapter. You may also use the performance objectives as activities to assess student learning.) 1.1 What are some principles of sustainability? Environmental science is an interdisciplinary study of how humans interact with the living and nonliving parts of their environment. CONCEPT 1-1A Nature has sustained itself for billions of years by relying on solar energy, biodiversity, and chemical cycling—lessons from nature that we can apply to our lifestyles and economies. The concept of sustainability relies on recognizing the value of natural capital, recognizing that many human activities degrade natural capital, and using scientific information to inform solutions to environmental problems. CONCEPT 1-1B We could shift toward living more sustainably by applying full-cost pricing, searching for win-win solutions, and committing to sustaining the earth’s life-support system for future generations. An environmentally sustainable society is one that meets the needs of its people without compromising the resources available for future generations or the earth’s health. 1. What are some principles of sustainability that are key to long-term sustainability of life on this planet? 2. Explain the key components of sustainability. 3. Distinguish between renewable and nonrenewable resources. 4. Distinguish between more-developed countries and less-developed countries. 1-2 How are our ecological footprints affecting the earth? Economic growth and development policies must be implemented that will sustain the earth’s human population and provide for an environmentally sustainable society. Pollution is a fundamental environmental problem resulting from human activities. Commonly shared resources are often overexploited, and it is difficult to find ways to manage these resources. CONCEPT 1-2 As our ecological footprints grow, we are depleting and degrading more of the earth's natural capital. 5. What is environmental degradation? Give specific examples. 6. Explain and give examples of point source pollution and non-point source pollution. 7. What is the Tragedy of the Commons? Give examples of how shared resources are being degraded. 8. Explain the concept of ecological footprints. How does this model demonstrate we are living an unsustainable lifestyle? What does the role of culture play in ecological footprints? 1-3 Why do we have environmental problems? CONCEPT 1-3 Major causes of environmental problems are population growth, wasteful and unsustainable resource use, poverty, and exclusion of environmental costs of resource use from the market prices of goods and services. The lifestyles of many people in developed nations and some emerging nations (China, India) are built upon affluence – wealth that results in high levels of consumption and wasted resources. 8. Explain the five major causes of environmental problems. 9. Define exponential population growth. Describe the connection between exponential growth and environmental problems. 10. How does affluence impact the environment? 11. Distinguish among different environmental worldviews. How do environmental ethics contribute to decision making? 1-4 What is an environmentally sustainable society? Environmentally sustainable societies protect natural capital and live of the resources and services it provides. CONCEPT 1-4 Living sustainably means living off the earth's natural income without depleting or degrading the natural capital that supplies it. Individuals can make a difference in helping their communities become more sustainable. 12. Explain the concept of living sustainably. 13. Why is it critical that we shift to a more sustainable lifestyle? Key Terms environment environmental science ecology organisms species ecosystem environmentalism scientific principles of sustainability nutrients nutrient cycling natural capital natural resources ecosystem services social science principles of sustainability full-cost pricing resource inexhaustible resource renewable resource sustainable yield nonrenewable resources reuse recycling economic growth gross domestic product (GDP) per capita GDP economic development more-developed countries less-developed countries environmental degradation natural capital degradation pollution point sources nonpoint sources biodegradable pollutants nondegradable pollutants pollution cleanup pollution prevention ecological footprint per capita ecological footprint sustainability revolution exponential growth affluence poverty environmental worldview environmental ethics planetary management worldview stewardship worldview environmental wisdom worldview environmentally sustainable society natural income Outline 1-1 What are three principles of sustainability? A. Environmental science examines the complex relationships that connect us to the living and nonliving parts of our environment. It integrates natural sciences, social sciences, and humanities. Three goals of environmental science: 1. To learn how life on the earth has survived and thrived 2. To understand how we interact with the environment 3. To find ways to deal with environmental problems and live more sustainably. B. Three themes related to the long-term sustainability of life on earth (and central to this book) 1. Reliance on solar energy 2. Biodiversity (biological diversity) 3. Chemical cycling (nutrient cycling) C. Components of Sustainability 1. Natural capital (resources and ecological services) is critical for sustaining life on earth and human economies 2. Many human activities degrade natural capital 3. Environmental scientists seek scientific solutions to environmental problems 4. Searching for solutions often leads to conflicts which result in trade-offs 5. Individuals matter – personal choices and local actions have a significant impact D. Understanding Resources 1. Inexhaustible resources have an essentially continuous supply – the sun, for example. 2. Renewable resources can be replenished anywhere from hours to hundreds of years – forests, fish populations, etc. 3. Nonrenewable resources exist in a fixed quantity on the earth (or at least are not renewed on human time scales) – energy resources, metallic minerals, and nonmetallic minerals. 4. Reusing and recycling nonrenewable resources extends their supplies E. Measuring Economic Growth and Development 1. As the world's population increases, many countries are expanding their economies, which can lead to environmental problems. 2. The UN classifies nations according to GDP (the per capita market value of goods/services produced by businesses operating within the country). The more-developed countries have 17% of the world’s population, while consuming 88% of the world's resources and generating 75% of world's pollution and waste. 1-2 How are our ecological footprints affecting the earth? A. Rising population and increased resource use is resulting in environmental degradation (natural capital degradation). The 2005 Millennium Ecosystem Assessment from the UN reported that human activities have degraded about 60% of the earth's ecosystem services in the past 50 years. B. Pollutants are chemicals at high enough levels in the environment to harm people or other living organisms. 1. Point sources of pollutants are single, identifiable sources; such as automobiles or industrial plants. 2. Nonpoint sources are dispersed, such as pesticides in the air and water run-off; these are difficult to control. 3. Biodegradable pollutants are materials that natural processes can break down over time; such as human sewage and newspapers. 4. Nondegradable pollutants are substances and chemicals that natural process cannot break down. C. Managing pollution 1. Pollution cleanup (output pollution control): cleaning up pollutants after they have been produced 2. Pollution prevention (input pollution control): reduces or eliminates pollutant production 3. Environmental scientists emphasize prevention – more effective, cheaper in the long run D. The Tragedy of the Commons describes the overuse or degradation of common property and open access resources. Most users of an open access resource believe their actions have little impact. Eventually the cumulative effect of a large number of users exhausts the resource. Two major approaches to preserving these resources: 1. Use the shared resource at a rate below sustainable yield (use less, regulate access) 2. Converting the free-access resources to private ownership. Practical for some approaches, but not for resources like the atmosphere and ocean. E. Ecological footprints are a way to model resource consumption and environmental impact of human activity 1. Ecological footprint is the amount of biologically productive land and water needed to provide people in that area with an indefinite supply of renewable resources and to absorb and recycle the wastes and pollution produced by the resource use. 2. Ecological deficits occur when the ecological footprint exceeds the biological capacity of that area to replenish its renewable resources and absorb the resulting waste/pollution 3. The WWF estimates we need 1.5 earths to support the resources currently consumed by the human population. 4. A per capita ecological footprint is an estimate of the earth's renewable resources an individual consumes. It would take five more planet earths for the rest of the world to reach the current US levels of renewable resource consumption. F. Case Study: China's New Affluent Consumers 1. China is rapidly becoming one of the world's leading consumer countries, with a growing ecological footprint to match. China now contains two-thirds of the world's most polluted cities. 2. As China's economy and population continues to grow, they will need a significant portion of or even exceed the world's current food, material, and energy resources to support the population. G. Cultural Changes Can Grow or Shrink Our Ecological Footprints 1. In the course of human existence (about 200,000 years), three cultural revolutions have significantly changed the way of life for people. Each improved the livelihood of people, allowing them to live longer. However, each revolution also increased resource use, pollution, and environmental degradation. 2. Agricultural revolution occurred 10,000-12,000 years ago: humans learned to grow and breed plants and animals for food, clothing, and other purposes. 3. Industrial-Medical revolution occurred 275 years ago: people invented machines for large-scale production, learned to extract energy from fossil fuels, and grow food in large quantities. Medical advances also allowed people to live longer. 4. Information-Globalization revolution began about 50 years ago, when information and resources began to be shared on a global level. 5. Environmental scientists see evidence for a fourth revolution: a Sustainability Revolution to transform our society into one that uses resources more sustainably. 1-3 Why do we have environmental problems? A. Five major causes of environmental problems are: population growth, unsustainable resource use, poverty, failure to include environmental costs in the market prices of goods and services, and increasing isolation from nature among a growing number of people. B. Population Growth 1. Exponential growth in the human population means that we add 80 million people each year to the earth's population. World's population is currently about 7.1 billion; by 2050 there could be 9.6 billion people on the planet. 2. The population growth rate can be slowed by reducing poverty through economic development, promoting family planning, and elevating the status of women. C. Affluence 1. The lifestyles of many consumers are built on affluence – growing wealth that results in high consumption and unnecessary waste of resources. 2. Americans are significant contributors to the environmental problems resulting from wealth: According to some ecological footprint calculators, it takes 27 tractor-trailer loads of resources per year to support one American. Some estimates indicate that the US is responsible for almost half the global ecological footprint. 3. Benefits of affluence include: education, as well as technology development to reduce pollution, environmental degradation and resource waste. We also benefit from an abundant, safe food supply and reduction in disease resulting in a longer life-span. D. Poverty 1. Worldwide, 900 million people live in extreme poverty. 2. Decisions made for short-term survival often result in environmental degradation and pollution. 3. Health problems related to pollution and environmental degradation include malnutrition, lack of access to clean water and sanitation, and severe respiratory disease from breathing smoke of open fires or poorly vented stoves. E. Prices 1. Prices of goods and services do not include the environmental costs of their production. F. Environmental Worldviews 1. Your environmental worldview is a set of assumptions and values that reflect how you think the world works and what your role should be. People differ in these values, adding to the difficulty in solving environmental problems. 2. Environmental ethics form an important part of these worldviews: Why should we care about the environment? Should every person be entitled to equal protection from environmental hazards, and others? 3. Planetary Management Worldview sees nature as existing to meet human needs. 4. Stewardship Worldview enlists humans to be responsible stewards of the Earth while seeking its benefits. 5. Environmental Wisdom Worldview holds that humans are part of and dependent on nature and that nature exists for all species. 1-4 What is an environmentally sustainable society? A. Our goal: environmentally sustainable society 1. An environmentally sustainable society meets the current and future basic resource needs of people in a just and equitable manner without compromising the ability of future generations to meet their basic needs 2. To do this, we need to protect our natural capital from depletion or degradation and live on its “income” – the resources (food, clean air/water, etc.) provided by the earth's systems. B. Individuals Matter: What can I do? 1. Scientific evidence that we have between 50-100 years to make a new cultural shift to a more sustainable living. The good news is that it takes 5-10% of a population of a community to make a major change, often in a shorter time than many people think. 2. Rely more on renewable energy from the sun to meet most of our heating and electricity needs. 3. Protect biodiversity and restore areas that have been degraded 4. Sustain chemical cycles by reducing wastes and pollution, not overloading systems with harmful chemicals, and not removing natural chemicals faster than they can be replenished. Teaching Tips 1. Consider beginning the first class using a short icebreaker activity of your choice. Icebreaker activities can help you get to know your students and help them get to know each other. Depending on the class size, you may want to have the students share what they have learned with one another in small groups or as a class. 2. During or after the icebreaker activity is a good time to ask probing questions, such as what students are expecting to learn and what they already know about environmental science. Are there particular topics the students would like to discuss or learn more about during the course? Any current environmental topics (local, regional, national, international) that have their attention? 3. Using informal questioning methods each session will help you assess what the students already know about a topic(s) before a lesson begins and will reveal the general knowledge base of the class. This information can then be used as a starting point for the lesson. This is especially important when discussing current events – you will be surprised at what students know... and what they don't know! 4. The first class period is also a good time to begin building a few predictable activities into the class. One of the shorter activities found in the Activities and Projects section would be an excellent element to incorporate into each class meeting. If you decide to use this as a warm-up activity, you may want to have students come back and revise their work after the completion of the lesson. 5. Another good idea is to use the performance objectives as follow-up learning activities. Successful completion of these objectives would indicate that key concepts in the chapter have been learned. Topics for Term Papers and Discussion Conceptual Topics 1. Population. UN population projections. Where will growth occur? What is impact of this growth in terms of environment (Resource use? Potential for environmental degradation?)? 2. Poverty. Definition; roots; worldwide distribution; possibilities to alter the current situation. 3. Technology. Research, development, and distribution of new technologies in the United States. 4. State of the world. Bibliography of current resources summarizing the state of the world; most important areas of concern. 5. Pollution and environmental degradation. Report on one form of pollution or environmental degradation, and describe its existence in different countries or choose one incident as a case study. Attitudes & Values 1. What is quality of life? 2. What is the history of conflict among pollution control, environmental degradation, and employment in the United States? Possible cases of interest include the automobile industry and fuel-efficiency standards, and the spotted owl and the logging industry. 3. Is the United States overpopulated? Explore factors that affect U.S. population size. 4. Is the world overpopulated? Have you been in countries that you felt to be overpopulated? Have you seen videos of countries that you felt to be overpopulated? 5. Is the country in which you live overpopulated? What factors contribute to your feelings? 6. Is your local community overpopulated? What do you feel are the costs and benefits of the population size of your community? 7. Do you favor slowing the growth rate of the world human population? What about slowing the growth rate of the human population in the country in which you live? 8. Do you favor growth management of the community in which you live or do you believe that people should be able to have as many children as they want? 9. Do you think the rate of resource consumption is too high? Provide at least three reasons to support your opinion. Do you think it’s important to change your consumption patterns? 10. Do you think the worldview of modern nations is compatible with sustaining, and even improving, environmental quality? If not, what is a more appropriate worldview and why? How can this worldview be promoted? Action-Oriented Topics 1. Computer modeling methods. Limits to Growth by Meadows and Meadows; today’s global climate models. 2. National. National efforts to address environmental needs; Blueprint for the Environment. 3. Global. Global attempts to address the environment and the economy; the UN document Our Common Future; the Earth Summit at Rio de Janeiro in 1992. Activities and Projects 1. In small groups of 3 or 4, compile a list of resources that are considered important today but were not recognized as resources 100 years ago. What are some things that have ceased to be significant resources during the last 50 years? What resources of the present will probably be of little value 50 years from now? Share the findings with the class. 2. Have the class make a list of changes in your community’s environment that have occurred over the last 10 years. Have students vote on which changes they consider desirable and which undesirable. Discuss the changes on which there is least consensus about desirability. Clarify the differences in values that underlie differences in students’ responses. 3. In small groups, have students assume roles as futurists. Have them describe life as they predict it will be in the year 2040. Have each group present to the class. 4. As a class, compile a list of natural resources pertinent to the functioning of the campus. Explore how those resources are utilized on campus. Determine if any of the resources are in danger of being depleted or degraded. Propose alternatives that might help the situation. Identify the appropriate decision-makers on your campus and offer them the results of your work. 5. As a class project, “adopt” a less developed country. Assign teams of students to investigate various aspects of the nation’s physical, population, economic, social, political, and other characteristics as well as lifestyle and life quality. Allocate class time for periodic reports and discussions of research results. 6. Find and share with the class songs, essays, poems, paintings, and literary passages that are strongly pro- or anti-technology. 7. As a class exercise, make lists of the beneficial and harmful consequences that have resulted from America’s adoption of automobile technology. 8. As a class project or extra-credit exercise, contact the local Department of Transportation (DOT) and find out if they offer an Adopt-A-Highway program. Adopt a stretch of highway and have the students pick up the litter. Students can keep tallies of the different types of litter collected (metal cans, snack food wrappers, etc.) and prepare a pie chart and report to submit to the DOT. BBC News Videos The Brooks/Cole Environmental Science Video Library with Workbook, featuring BBC Motion Gallery Video Clips, 2011. ISBN: 978-0-538-73355-7 (Prepared by David Perault) Jean Suppliers Pollution Plastic Bag Charge Debated Suggested Answers for Critical Thinking Questions 1. Student answers will vary, depending on their awareness of resource use or the environmental costs of their lifestyle. Environmentally unsustainable components of their lifestyle may include: type of vehicle they drive, wasting electricity (leaving lights on, etc.), wasting water, purchasing bottled water, frequent shopping, not recycling. Applying principles of sustainability: purchasing organic or sustainably generated products could fit in several areas below. Many products now have labels (some as a result of certifications from supervisory agencies, some are made up!) that make identifying these products somewhat easier (but occasionally misleading). Solar Energy: rely less on air conditioners – open windows and use fans instead of running air conditioning on milder days; rely less on heater – put on a sweater and keep thermostat a few degrees cooler on moderately cool days. Minimize use of materials derived from petroleum Biodiversity: use fewer plastic bags – carry your own instead; support efforts to reduce pollution, promote protection of wild lands Chemical Cycling: reduce pollution, purchase organic produce, start your own garden Economics: Purchase fair trade goods Politics: Campaign to change government policies Ethics: answers will vary, but will likely include making the changes that are present in the other categories 2. Principles of sustainability involved in the following actions: (a) recycling aluminum cans: solar, chemical cycling (b) using a rake instead of a leaf blower: solar (c) walking or bicycling to class instead of driving: solar, chemical cycling (d) taking your own reusable bags to the grocery store to carry your purchases home: solar, biodiversity, chemical cycling (e) buying the more expensive of two product because it was produced in a more sustainable fashion: Economics (e) volunteering to help restore a prairie: biodiversity, chemical cycling 3. Student answers will vary. 4. Student answers will vary – this is a good question to get them thinking about these issues on a personal level. Feelings of skepticism almost always lead away from habit change – if my actions aren't causing the problem, then why stop doing the things I like? Feelings of indifference or helplessness can perpetuate the problems of affluenza – if you feel your individual or your community's local actions won't have a positive impact, then why change? Guilt can go either way – for some it is paralyzing; for others, motivating. Concern or outrage usually leads to action, whether on the personal, local, or regional level. Some people are outraged enough to pursue environmental science as a career! 5. Students' familiarity with these challenges may vary significantly – many may be just beginning to grasp the scope of the problem through this course. If they are familiar with an organization supporting these causes, their answers may reflect opportunities for volunteering. Donations, club/campus projects to support communities in developing countries may come to mind. 6. Student answers will vary; encourage them to be as specific as possible about their thinking (or highlighting areas where they are unsure what influences their opinions). Having students articulate their opinions and explain the reasoning behind them is a good exercise at the beginning of the course. 7. While students' answers will vary, this is a good question to ask at the beginning and again at the end of the course – have students' ideas changed or evolved? Have they improved their ability to articulate what they think and offer specific examples to support it? Asking students to reflect if their actions reflect their worldview is a critical component to analyzing individual actions and promoting change in our habits. Chapter 2 Science, Matter, Energy, and Systems Summary and Objectives 2-1 What do scientists do? Science is an endeavor to discover how nature works and to use that learned knowledge to make predictions about future events. The natural world follows orderly patterns, which, through observation and experimentation, can be understood. CONCEPT 2-1 Scientists collect data and develop theories, models, and laws about how nature works. 1. Describe the steps involved in the scientific process. Distinguish among scientific hypothesis, scientific theory, and scientific (natural) law. 2. Distinguish between tentative or frontier science, reliable science and unreliable science. Explain the importance of peer review. Explain why people often use the term theory incorrectly. 3. What are some limitations of science? Describe statistics and probability, and describe how they are used in science. 2-2 What is matter and what happens when it undergoes change? The building blocks of matter are atoms, ions, and molecules, which form elements and compounds. These different aspects of matter have mass and take up space; they may be living or non-living. CONCEPT 2-2A Matter consists of elements and compounds that are in turn made up of atoms, ions, or molecules. CONCEPT 2-2B When matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter). 4. Define matter. Distinguish between forms of matter. Compare and contrast high-quality matter with low-quality matter and give an example of each. 5. Distinguish among a proton (p), neutron (n), and electron (e). What is the difference between the atomic number and the mass number? What is an isotope? 6. Distinguish between organic compounds and inorganic compounds. 7. What is the difference between a physical change and a chemical change? 8. What is the law of conservation of matter? 2-3 What is energy and what happens when it undergoes change? Energy is the capacity to do work and transfer heat; it moves matter. Thermodynamics is the study of energy transformation. CONCEPT 2-3A Whenever energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics). CONCEPT 2-3B Whenever energy is converted from one form to another in a physical or chemical change, we end up with lower-quality or less usable energy than we started with (second law of thermodynamics). 9. Define energy. Distinguish between forms of energy and quality of energy. Distinguish between high-quality energy and low-quality energy and give an example of each. 10. Describe how the law of conservation of matter and the law of conservation of energy govern normal physical and chemical changes. Briefly describe the second law of thermodynamics. Explain why this law means we can never recycle or reuse high-quality energy. 2-4 What keeps us and other organisms alive? Ecology is the study of connections in the natural world among organisms, populations, communities, ecosystems, and the biosphere. The earth's life-support system consists of the geosphere, biosphere, hydrosphere, and atmosphere. CONCEPT 2-4 Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity. 11. Distinguish between organism, species, population, community, ecosystem, and biosphere. 12. Explain genetic diversity and how it contributes to biological communities. 13. Distinguish between the atmosphere, troposphere, and stratosphere. Define greenhouse gases and give two examples. What is the natural greenhouse effect? 14. List four spheres that interact to sustain life on Earth. Compare the flow of matter and the flow of energy through the biosphere. 2-5 What are the major components of an ecosystem? Ecosystems are made up of abiotic (nonliving) components: water, air, nutrients, and solar energy, as well as biotic (living) components: plants, animals, and microbes. Producers, consumers, and decomposers cycle matter, energy, and nutrients in an ecosystem. CONCEPT 2-5 Ecosystems contain nonliving and living components, including organisms that produce the nutrients they need, organisms that get the nutrients they need by consuming other organisms, and organisms that recycle nutrients by decomposing the wastes and remains of other organisms. 15. Distinguish between biotic and abiotic components of the biosphere and give two examples of each. 16. Define range of tolerance and the limiting factor principle. Give one example of a limiting factor in an ecosystem. 17. Distinguish between producers, consumers, and decomposers. List and distinguish between two types of producers and four types of consumers. Describe the concept of trophic levels. 2-6 What happens to energy in an ecosystem? Ecological interdependence can be described in food chains and webs, energy flow, ecological efficiency, and the production of biomass. CONCEPT 2-6 As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases. 18. Apply the second law of energy to food chains and pyramids of energy flow. Explain ecological efficiency. 19. Discuss the difference between gross primary productivity and net primary productivity. 2-7 What happens to matter in an ecosystem? Major cycles in ecosystems are the nutrient cycle, the hydrologic cycle, the carbon cycle, the nitrogen cycle, the phosphorus cycle, and the rock cycle. The carbon cycle produces carbon dioxide, and with more of it being released into the atmosphere, the world is now being affected by global warming. CONCEPT 2-7 Matter, in the form of nutrients, cycles within and among ecosystems throughout the biosphere, and human activities are altering these chemical cycles. 20. Describe the hydrologic (water), carbon, nitrogen, or phosphorus cycle and describe how human activities are affecting each cycle. 21. List three types of rock and describe their interactions through the rock cycle. Key Terms science data experiments scientific hypothesis model scientific theory peer review scientific law (law of nature) tentative or frontier science reliable science unreliable science probability matter element compounds atom atomic theory neutrons protons electrons nucleus atomic number mass number isotopes molecule chemical formula ion acidity pH organic compounds inorganic compounds genes trait chromosome cell matter quality high-quality matter low-quality matter physical change chemical change or reaction law of conservation of matter energy kinetic (moving) energy heat electromagnetic radiation potential (stored) energy principle of sustainability energy quality high-quality energy low-quality energy first law of thermodynamics law of conservation of energy second law of thermodynamics ecology organism species population genetic diversity habitat community biological community ecosystem biosphere atmosphere troposphere greenhouse gases stratosphere hydrosphere geosphere biomes aquatic life zones nutrients natural greenhouse effect biotic abiotic range of tolerance limiting factors limiting factor principle trophic level producers autotrophs photosynthesis consumers heterotrophs primary consumers herbivores carnivores secondary consumers tertiary consumers omnivores decomposers detritus feeders detritivores aerobic respiration ecological tipping point food chain food web biomass ecological efficiency pyramid of energy flow gross primary productivity (GPP) net primary productivity (NPP) biogeochemical cycles nutrient cycles hydrologic (water) cycle evaporation precipitation transpiration carbon cycle nitrogen cycle phosphorus cycle rock igneous rock sedimentary rock metamorphic rock rock cycle Outline 2-1 What Do Scientists Do? A. Science assumes that events in the natural world follow orderly patterns and that, through observation and experimentation, these patterns can be understood. Scientists collect data, form hypotheses, and develop theories, models, and laws to explain how nature works. 1. Scientists identify a problem, find out what is known about the problem, ask a question to investigate, and conduct experiments to collect data in order to answer the question. 2. Based on observations of phenomenon, scientists form a scientific hypothesis—a possible explanation of the observed phenomenon that can be tested. 3. Using the hypothesis, scientists make testable projections and perform further experiments (or observations) in order to accept or reject the hypothesis. (See Science Focus: Statistics and Probability) 4. Important features of the scientific process are curiosity, skepticism, reproducibility, and peer review. B. A scientific theory is a verified, believable, widely accepted scientific hypothesis or a related group of scientific hypotheses. 1. Theories are explanations that are likely true, supported by evidence. 2. Theories are the most reliable knowledge we have about how nature works. C. A scientific/natural law describes events/actions of nature that reoccur in the same way, over and over again (such as effects of gravity on falling objects). D. The reliability of scientific results relies on the reliability of how the experiments are conducted and interpreted. 1. Preliminary scientific results can be described as tentative science (or frontier science). These results have not yet been widely tested or accepted by peer review, yet they are often featured in news headlines. These results are not reliable, as they have not been extensively tested. Scientists may disagree over the interpretation and accuracy of the data and conclusions. 2. Reliable science, or scientific consensus, is hypotheses, models, theories, and laws that are widely accepted by most scientists that are experts in that field of study. These results have been peer reviewed and are reproducible. 3. Unreliable science is that which has not undergone peer review or has been discarded as a result of peer review. E. Limitations of Science 1. There is always some degree of uncertainty in scientific measurements, models, observations. 2. Scientists are human and may be biased. Peer review greatly reduces this. 3. Many systems in science (especially environmental science) are very complex, making it difficult to test each variable. Mathematical models help simply complex analyses and modeling. 4. Statistical tools such as sampling and estimation are important aspects of models. 5. The scientific process can tell us about the natural world, not about the moral or ethical questions related to the topic being examined. 2-2 What Is Matter and What Happens When It Undergoes Change? A. Matter is anything that has mass and takes up space, living or not. 1. An element is the distinctive building block that makes up every substance. 2. A compound is two or more different elements held together in fixed proportions by chemical bonds. B. The building blocks of matter are atoms, ions, and molecules. 1. An atom is the smallest unit of matter that exhibits the characteristics of an element. 2. An ion is an electrically charged atom or combination of atoms. 3. A compound is a combination of two or more atoms/ions of elements held together by chemical bonds. C. An atom contains a nucleus with protons, usually neutrons, and one or more electrons moving outside the nucleus; it has no electrical charge. 1. Subatomic particles in an atom are of three types: a. Protons have a positive electrical charge. b. Neutrons have no electrical charge. c. Electrons have a negative electrical charge. 2. The nucleus is the very, very small center of the atom. 3. Each element has its own atomic number that equals the number of protons in the nucleus of each atom. [H has 1 proton and, therefore, the atomic number of 1; uranium has 92 protons and an atomic number of 92.] 4. Most of an atom's mass is found in the nucleus. The mass number is the total number of neutrons and protons in its nucleus. D. All atoms of an element have the same number of nuclei protons; but they may have different numbers of uncharged neutrons in their nuclei. As a result, atoms may have different mass numbers. These are called isotopes. E. Molecules are combinations of atoms held together by chemical bonds. Chemical formulas show the number and type of atoms or ions in the compound. 1. Each of the elements in the unit is represented by symbols: H=water, N=nitrogen. 2. Subscripts show the number of atoms/ions in the unit. F. Ions are atoms with a net positive or negative electrical charge, resulting from the gain or loss of electrons (respectively). Ions are important for measuring a substance's acidity in water. G. Organic compounds contain combinations of carbon atoms and atoms of other elements. Only methane (CH4) has only one carbon atom. 1. Hydrocarbons: compounds of carbon and hydrogen atoms. Examples include methane (component of natural gas) and octane (component of gasoline) 2. Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms. Examples include the pesticide DDT. 3. Simple carbohydrates (simple sugars): specific types of compounds of carbon, hydrogen, and oxygen atoms. Example: glucose 4. Macromolecules are larger, more complex organic compounds, many of which are essential to life. These include complex carbohydrates (cellulose, starch), proteins, and nucleic acids (DNA, RNA). 5. DNA contains genes, specific sequences that code for traits that can be passed to offspring. These genes make up chromosomes, DNA that is highly organized and tightly wrapped around proteins. These building blocks come together to form cells, the fundamental unit of living things. H. According to the usefulness of matter as a resource, it is classified as having high or low quality. 1. High-quality matter is highly concentrated, often found near the earth's surface. 2. Low-quality matter is dilute, may be found deep underground and/or dispersed in air or water. I. Although matter can change forms or re-combine into new substances, it cannot be created or destroyed. 1. Physical change: no change in the chemical composition of the matter. 2. Chemical change: chemical compositions do change; new compounds are formed. Chemical equations show how atoms and ions are rearranged to form new products. 3. Law of conservation of mater: atoms are not created or destroyed during physical or chemical changes. 4. This law means there is no “away” when we “throw something away”. We will always have to address the pollutants and wastes that we produce. 2-3 What Is Energy and What Happens When It Undergoes Change? A. Energy is the capacity to do work and transfer heat; it moves matter. 1. Kinetic energy has mass and speed; wind, electricity, and heat are examples. 2. Electromagnetic radiation is a form of kinetic energy in which energy travels in the form of a wave. These waves have many forms as described by their differing energy contents: X rays, UV radiation, and visible light are examples. 3. Potential energy is stored energy, ready to be used; an unlit match, for example. 4. Potential energy can be changed into kinetic energy. The direct input of solar energy to the earth produces other indirect forms of renewable energy, including wind, hydropower, and biomass. 5. Energy quality is measured by its usefulness; high energy is concentrated and has high usefulness. Low energy is dispersed and can do little work. B. The Laws of Thermodynamics govern energy changes 1. The First Law of Thermodynamics states that energy can neither be created nor destroyed. 2. The Second Law of Thermodynamics states that when energy is changed from one form to another, there is always less usable energy; energy quality is depleted. In energy changes, the resulting low-quality energy is often heat which dissipates into the air. 3. In living systems, solar energy is changed to chemical energy (food) and then in to mechanical energy (moving, thinking, living). During each conversion, high-quality energy is degraded and flows into the environment as low-quality heat. 4. The Second Law of Thermodynamics also means we can never recycle high-quality energy to perform useful work. Once the concentrated energy is used, it is degraded to low-quality heat that dissipates into the atmosphere. 2-4 What Keeps Us and Other Organisms Alive? A. Ecology is the study of connections in the natural world. An ecologist’s goal is to try to understand interactions among organisms, populations, communities, ecosystems, and the biosphere. 1. An organism is any form of life. The cell is the basic unit of life in organisms. 2. Organisms are classified into species, which groups organisms similar to each other together. B. A population consists of a group of interacting individuals of the same species occupying a specific area. 1. Genetic diversity explains that these individuals may have different genetic makeup and, thus, do not behave or look exactly alike. 2. The habitat is the place where a population or an individual usually lives. C. A community represents populations of different species living and interacting in a specific area – the network of plants, animals, and microorganisms. (See Science Focus: Have You Thanked the Insects Today?) D. An ecosystem is a community of different species interacting with each other and with their nonliving environment of matter and energy. All of the earth’s diverse ecosystems comprise the biosphere. E. Various interconnected spherical layers make up the earth’s life support system. 1. The atmosphere is the thin membrane of air around the planet. The troposphere (up to 17 km above sea level) contains air we breathe, our weather, and greenhouse gases, while the stratosphere (17-50 km above earth) holds the UV-protective ozone layer. 2. The hydrosphere consists of the Earth's water (liquid, ice, and vapor) 3. The geosphere is made of rock mostly inside the earth: crust, mantle, and core. 4. The biosphere contains all life on earth, including parts of the atmosphere, hydrosphere, and geosphere. Land regions are classified into biomes (forests, deserts, grasslands) with distinct climates and animals/vegetation specifically adapted to them. Biosphere extends from ocean floor to 9 km above the earth's surface. F. High-quality energy from the sun, nutrient cycles, and gravity sustain life on Earth. G. Solar energy reaches the earth in the form of visible light, infrared radiation (heat), and ultraviolet radiation. 1. Much of this energy is absorbed or reflected back into space by the atmosphere. 2. Greenhouse gases trap the heat and warm the troposphere. This natural greenhouse effect makes the planet warm enough to support life. 2-5 What Are the Major Components of an Ecosystem? A. The major components of ecosystems are abiotic (nonliving) water, air, nutrients, and solar energy; and biotic (living) plants, animals, and microbes. B. Each population in an ecosystem has a range of tolerance to variations in its physical and chemical environments. 1. The limiting factor principle states that too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimum range of tolerance. 2. Water or nutrients can be limiting factors on land, while dissolved oxygen, nutrients, and temperature can be limiting factors in aquatic systems. C. Every organism in an ecosystem can be classified according to its trophic level (feeding level), as defined by its source of nutrients. 1. Producers: autotrophs make their own food/nutrients (plants). All consumers rely on producers for their nutrients. 2. Consumers: heterotrophs may feed on both producers (plants) and other consumers (animals), or may feed on plants alone (herbivores). 3. Decomposers: detritivores feed on wastes and dead organisms and recycle the nutrients back to the ecosystem – key role in nutrient cycling. (See Science Focus: Many of the World’s Most Important Species Are Invisible to Us) 2-6 What Happens to Energy in an Ecosystem? A. Food chains and food webs help us understand how producers, consumers, and decomposers are connected to one another as energy flows through trophic levels in an ecosystem. B. The chemical energy stored in biomass is transferred from one trophic level to another, but some energy is degraded and lost to the environment as low-quality heat. As you go “up” the food chain, there is a decrease in the amount of high-quality energy available to each organism at succeeding feeding levels. 1. The percentage of usable chemical energy transferred as biomass from one trophic level to the next is called ecological efficiency. 2. Typically, 10% of usable chemical energy is transferred to the next level in the food chain. 3. Energy flow pyramids illustrate how the earth could support more people if they eat at a lower trophic level. Food webs and food chains rarely have more than 4 or 5 trophic levels due to the significant loss of energy at each level. C. Production of biomass takes place at different rates among different ecosystems. 1. The rate of an ecosystem’s producers converting energy as biomass is the gross primary productivity (GPP). 2. Some of the biomass must be used for the producer’s own respiration. Net primary productivity (NPP) is the rate at which producers use photosynthesis to store biomass minus the rate at which they use energy for aerobic respiration. NPP measures how fast producers can provide biomass needed by consumers in an ecosystem. 3. The planet’s NPP limits the number of consumers who can survive (including humans!). 4. Ecologists estimate that humans now use, waste, or destroy 10-55% of the earth's entire potential NPP. 2-7 What Happens to Matter in an Ecosystem? A. Nutrient cycles (biogeochemical cycles) are global recycling systems that interconnect all organisms. 1. Nutrient atoms, ions, and molecules continuously cycle between air, water, rock, soil, and living organisms. 2. These cycles include the carbon, oxygen, nitrogen, phosphorus, and water cycles. They are connected to chemical cycles of the past and the future. B. The water/hydrologic cycle collects, purifies, and distributes the earth’s water in a vast global cycle. 1. Solar energy evaporates water, the water returns as rain/snow, goes through organisms, goes into bodies of water, and evaporates again. 2. Some water becomes surface runoff; returning to streams/rivers, causing soil erosion, and also being purified itself. 3. Water is a major medium for transporting nutrients within and between ecosystems. 4. About 0.024% of the earth's water supply is available as liquid fresh water in accessible groundwater deposits, lakes, rivers, and streams. C. The water cycle is altered by man’s activities. 1. We withdraw large quantities of fresh water, often at a rate at is faster than nature can replace it. 2. We clear vegetation, which increases runoff, reduces filtering, and increases flooding. 3. We increase flooding when we drain wetlands for farming or development. D. The carbon cycle circulates through the biosphere. Carbon moves through water and land systems, using processes that change carbon from one form to another. 1. CO2 gas is an important temperature regulator on Earth. 2. Photosynthesis in producers and aerobic respiration in consumers, producers, and decomposers circulates carbon in the biosphere. 3. Fossil fuels contain carbon; in a few hundred years we have almost depleted these fuels that have taken millions of years to form. E. Addition of excess carbon dioxide to the atmosphere through our use of fossil fuels and our destruction of the world’s photosynthesizing vegetation has contributed to changes in global climate F. Bacteria are critical to the nitrogen cycle, converting nitrogen compounds into those that can be used by plants and animals as nutrients. 1. In nitrogen fixation, gaseous N2 is converted to ammonia, which is converted to ammonium ions that are useful to plants. 2. Ammonia not used by plants may undergo nitrification, a conversion process that uses bacteria to convert the nitrogen to nitrite ions (toxic to plants) and nitrate ions (easily taken up by plants). 3. Decomposer bacteria convert detritus into ammonia and ammonium ion salts in ammonification. 4. In denitrification, nitrogen is returned to a gaseous form and released into the atmosphere. G. Human activities affect the nitrogen cycle. 1. In burning fuel, we add nitric oxide into the atmosphere; it can return to the earth’s surface as acid rain. 2. Nitrous oxide that comes from livestock, wastes, and inorganic fertilizers we use on the soil can warm the atmosphere and deplete the ozone layer. 3. We destroy forest, grasslands, and wetland, thus releasing large amounts of nitrogen into the atmosphere. 4. We pollute aquatic ecosystems with agricultural runoff and human sewage. 5. We remove nitrogen from topsoil with our harvesting, irrigating, and land-clearing practices. H. The phosphorous cycle circulates through the water, the earth's crust, and living organisms. 1. Phosphate ions transferred throughout the food chain, from producers to consumers to decomposers. 2. Phosphates that end up in the ocean can remain trapped in sediment for millions of years 3. Phosphates are often limiting factors for plant growth on land as well as producer populations in aquatic environments. 4. an interferes with the phosphorous cycle in harmful ways such as mining phosphate rock to produce fertilizers and detergents, cutting down tropical forests, and increasing phosphates in aquatic environments with animal waste runoff and human sewage. I. The planet’s slowest cyclical process is the rock cycle. 1. Igneous rock forms when magma (volcanic rock material) comes from the earth’s crust, cools, and hardens. 2. Sedimentary rock is formed when sediment is weathered and eroded, moved from its source, and deposited in a body of water. The layers weather, erode, and become buried and compacted. This process binds the particles together and forms sedimentary rock, rocks such as sandstone and shale. 3. When rock is exposed to high temperatures, high pressures, chemically active fluids, or a combination of these things, metamorphic rock is formed. 4. The rock cycle concentrates the earth's nonrenewable mineral resources (on which we depend). Teaching Tips 1. Remember when planning for the lesson, take a moment to go back and review the performance objectives listed under each key concept. Build these performance objectives into the lesson, using them as checkpoints for student understanding as the lesson unfolds. Also, take these performance objectives into consideration when incorporating outside material(s) into the lesson. 2. Recall that using informal questioning methods each session can be highly effective in helping assess what the students already know about a topic(s) before a lesson begins, and will also reveal the general knowledge base of the class. When using this method, be aware that sometimes you may expose a topic that students have little prior knowledge of or misconceptions about. If this occurs, focus attention on preparing the students for the information to come. Try to make a relevant connection between something the students are already familiar with and what they are about to learn. 3. Critical thinking activities are an excellent element to incorporate into each class meeting. The following is a possible warm-up activity for Chapter Two that can also be found under the Activities and Projects section. How do you feel when your home is air conditioned? Heated? How do you feel when you turn on a light? The television? Your CD player? What rights do you have to Earth’s energy resources? Are there any limits to your rights? What are they? 4. Have the students come back and revise their answers after the completion of the lesson. Depending on the class size, you may want to have the students share what they have learned with one another in small groups or as a class. Topics for Term Papers and Discussion Conceptual Topics 1. Low-energy lifestyles. Individual case studies such as Amory Lovins and national case studies such as Sweden. Many local, regional, and national organizations are providing information for decreasing individual's energy use. 2. Nature’s cycles and economics. Recycling attempts in the United States; bottlenecks that inhibit recycling; strategies that enhance recycling efforts. What types of recycling programs are available in your area? 3. Cycles of matter. Particular cycles of matter, clarifying chemical changes throughout the cycle; the processes of photosynthesis and respiration, and how they connect autotrophic and heterotrophic organisms. 4. Energy flow. Energy flow in a particular ecosystem; relationships between species in a particular ecosystem; comparison of the life of a specialist with that of a generalist. 5. Humans trying to work with ecosystems. Composting; organic gardening; land reclamation; rebuilding degraded lands; tree-planting projects; landscaping with native plants. Attitudes & Values 1. How much are you willing to pay in the short run to receive economic and environmental benefits in the long run? Explore costs and payback times of energy-efficient appliances, energy-saving light bulbs, or hybrid vehicles. 2. Can we get something for nothing? Explore the attempts of advertising to convince the public that we can indeed get something for nothing. What does it mean when people say “there's no such thing as a free lunch”? How do these factors impact our perceived wants and needs? 3. Is convenience more important than sustainability? Explore the influence of U.S. frontier origins on the throwaway mentality. 4. Do you hold any particular feelings for producers? Consumers? Decomposers? How do you feel when you think of a coyote eating a rabbit? How do you feel when you think of humans eating hamburgers? Should we eat lower on the food chain? 5. Should we rely more on perpetual sources of energy? What kinds of changes in our energy sources do you expect to see in the coming 10-20 years? 6. What lessons for human societies can be drawn from a study of species interaction in ecosystems? 7. To what extent should we disrupt and simplify natural ecosystems for our food, clothing, shelter, and energy needs and wants? To what extent do we actually disrupt these systems? What can individuals do to change this? 8. What do nature’s cycles of matter suggest about landfills, incinerators, reducing consumption, and recycling? 9. How do you feel when your home is air conditioned? Heated? How do you feel when you turn on a light? The television? Your CD player? What rights do you have to Earth’s energy resources? Are there any limits to your rights? What are they? 10. Based on your current understanding of energy flow and cycles of matter, evaluate the emphasis in the United States on fossil fuels and nuclear power for energy production. Action-Oriented Topics 1. Individual. Actions that improve energy efficiency and reduce consumption of materials. Field and laboratory methods used in ecological research. Measuring net primary productivity and respiration rates; analyzing for particular chemicals in the air, water, and soil. 2. Community. Enhance recycling efforts: curbside pickup versus recycling center drop-offs; high-tech versus low-tech sorting of materials; Osage, Iowa, a case study in community energy efficiency. 3. Regional. Restoration of degraded ecosystems such as Lake Erie; coastal zone management. 4. National energy policy. Evaluation of the current national energy policy proposals in light of the laws of energy and long-term economic, environmental, and national-security interests. Activities and Projects 1. A human body at rest yields heat at about the same rate as a 100-watt incandescent light bulb. As a class exercise, calculate the heat production of the student body of your school, the U.S. population, and the global population. Where does the heat come from? Where does it go? 2. As a class exercise, conduct a survey of the students at your school to determine their degree of awareness and understanding of the three matter and energy laws. Discuss the results in the context of the need for sustainable-earth societies. 3. As a class exercise, have each student list the kinds and amounts of food he or she has consumed in the past 24 hours. Aggregate the results and compare them on a per capita basis with similar statistics derived from studies of dietary composition and adequacy in food-deficient nations. How many people with a vegetarian diet could subsist on the equivalent food value of the meat consumed by your class? 4. Have the students debate the argument that eating lower on the food chain is socially and ecologically more responsible, cheaper, and healthier. (It is helpful to do this around a time when fasting is common.) Also, look at the long-term picture: Will eating low on the food chain sustain an exponentially growing human population indefinitely? What kinds of changes would this mean to your diet? How willing are you to change? 5. Define an ecosystem to study on campus. As a class project, analyze the nonliving and living components of the ecosystem. Draw webs and construct pyramids to show the relationships between species in the ecosystem. Project what might happen if pesticides were used in the ecosystem, if parts of the ecosystem were cleared for development, or if a coal-burning power plant were located upwind. 6. Ask a physics professor of physics lab instructor to visit your class and, by using simple experiments, demonstrate the matter and energy laws. 7. Organize a class trip to a natural area such as a forest, grassland, or estuary to observe the elements of ecosystem structure and function. Arrange for an ecologist or naturalist to provide interpretive services. 8. Bring a self-sustaining terrarium or aquarium to class and explain the structure and function of this conceptually tidy ecosystem. Discuss the various things that can upset the balance of the ecosystem and describe what would happen if light, food, oxygen, or space were manipulated experimentally. BBC News Videos The Brooks/Cole Environmental Science Video Library with Workbook, featuring BBC Motion Gallery Video Clips, 2011. ISBN: 978-0-538-73355-7 (Prepared by David Perault) Who Pays The Price for Technology? Suggested Answers for Critical Thinking Questions 1. Student answers will vary. They should emphasize the process of observation, creating hypothesis to explain or predict future behavior, testing the hypothesis, and then revising the hypothesis. 2. (a) Scientists can disprove things but they cannot prove anything absolutely because there is always some inherent uncertainty in making measurement, observations, and using models. Yet, the process of science means that many different experiments will be conducted from many different perspectives to try and understand if there is a connection between smoking and death. Scientific consensus develops over time, and new ideas are continually evaluated to see if a more accurate explanation can be developed. (b) This statement misinterprets the meaning of a scientific theory. The natural greenhouse theory is reliable because a scientific theory is related to a body of observations or measurements that have been well-tested and widely-accepted by the scientific community. 3. This phenomenon is not in violation of the law of conservation of matter because, while the tree is growing, it is doing so through physical and chemical changes without creating or destroying atoms. The tree is deriving matter in the form of nutrients from the earth, water, and the atmosphere, and when it dies this matter will be returned to their cycles. 4. The second law of thermodynamics states that energy always goes from a more-useful to a less-useful form when it is changed from one form to another. When a barrel of oil is used for energy, most of the energy is given off as heat, a lower-quality energy. You are unable to recycle or reuse the high-quality energy because once it has been converted into low-quality energy, or heat, it is lost to the environment. 5. (a) Energy from the sun flows through living organisms in their feeding relationships and out into the environment mainly as heat lost. The flow of energy through the biosphere depends on the cycling of nutrients because producers convert energy from the sun to nutrients for consumers and detritivores, which recycle nutrients back to producers. (b) The cycling of nutrients depends on gravity because it allows the planet to maintain its atmosphere. Gravity enables the movement and cycling of chemicals through the air, water, soil, and organisms. 5. Student answers will vary. Students should be able to trace their foods back to a producer species – but it might take some research for them to figure out what some of those intermediary organisms eat. As the course progresses, students may return to this thinking about their feeding level and the impact it has on the environment. 7. (a) If all the decomposers and detritus feeders were eliminated from an ecosystem, waste and dead organisms would build up and there would be no cycling of nutrients, as the detritivores aid in the breakdown of waste products into basic nutrients needed to support life. (b) If all the producers were eliminated from an ecosystem, consumers or heterotrophs would suffer as they have no way of producing their own energy. All higher trophic levels would also suffer and would most likely result in the halt of energy transfer through the ecosystem. (c) If all insects were eliminated from an ecosystem, energy transfer and matter cycling through the ecosystem would be greatly altered. Insects fill important rolls such as detritivores and primary consumers; they also make up a major food/energy source to other organisms. Insects are also needed as pollinators for sexual reproduction in plants. A balanced ecosystem cannot exist with only producers and decomposers. A healthy ecosystem depends on species diversity. Consumers maximize the rate of flow of energy and cycling of matter through ecosystems. All trophic levels are necessary for balanced nutrient cycling and energy flow. 8. Often, farmers need to add fertilizer containing nitrogen and phosphorous to their crops, without having to add carbon. The reason for this is because carbon is far more abundant than nitrogen and phosphorous. Nitrogen or phosphorus is often the limiting factor. They are essential nutrients for growing crops. Instructor Manual for Sustaining the Earth G. Tyler Miller, Scott E. Spoolman 9781285769493