1. Chapter 1 Key Themes in Environmental Sciences

2. Major Themes of Environmental Science Human population growth An urbanizing world Sustainability of our population and all of nature People and nature A global perspective Science and values

3. Human Population Growth The human population grew at a rate unprecedented in history in the twentieth century. Population growth is the underlying environmental problem. Famine is one of the things that happen when a human population exceeds its environmental resources. An example is African Famine.

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5. An Urban World When the impact of technology is combined with the impact of population, the impact on the environment is multiplied. In an increasingly urban world, we must focus much of our attention on the environments of cities and on the effects of cities on the rest of the environment.

6. Sustainability and Carrying Capacity What is the maximum number of people the Earth can sustain?

7. Sustainability Sustainable resoruce harvest –An amount of a resource that can be harvested at regular intervals indefinitely Sustainable ecosystem –An ecosystem that is subject to some human use, but at a level that leads to no loss of species or of necessary ecosystem functions

8. Science and Values To make decisions about an environmental problem we: –Know what is possible based on science –Choose the best option based on our values

9. Precautionary Principle Precautionary Principle states that we should not wait for scientific proof before taking action to prevent environmental damage. Ex. San Francisco

10. Chapter 2 Science as a Way of Knowing

11. Science as Process Science is a process of discovery –Scientific ideas change –Sometimes a science undergoes a fundamental revolution of ideas

12. Science as Process The criterion by which we decide whether a statement is in the realm of science: Whether it is possible, at least in principle, to disprove the statement.

13. Disprovability If you can think of a test that could disprove a statement, then that statement can be said to be scientific. If you can’t think if a test, then the statement is said to be nonscientific.

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15. Science as Process Scientific Method: Actually a set of methods which are the systematic methods by which scientists investigate natural phenomena

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17. Assumptions of Science Events in the natural world follow patterns that can be understood through careful observation and scientific analysis. These basic patterns and rules that describe them are the same through the universe Science is based on a type of reasoning known as induction Generalizations can be subjected to tests that may disprove them. Although new evidence can disprove existing theories, science can never provide absolute proof of the truth of its theories.

18. The Nature of Scientific Proof Deductive reasoning: –Drawing a conclusion from initial definitions and assumptions by means of logical reasoning. Inductive reasoning: –Drawing a conclusion from a limited set of specific observations.

19. Deductive reasoning Example 1 –Premise: a straight line is the shortest distance between two points. –Premise: The line from A to B is the shortest distance between points A and B. –Conclusion: Therefore, the line from A to B is a straight line. Proof does not require that the premises be true, only that the reasoning foolproof.

20. Deductive reasoning Example 2 –Premise: Humans are the only toolmaking organisms. –Premise: the woodpecker finch uses tools. –Conclusion: Therefore, the woodpecker finch is a human being.

21. Inductive reasoning Science requires not only logical reasoning but also correct premises. Generalizations based on a number of observations = inductive reasoning.

24. Measurements and Uncertainty Experimental errors: –Measurement uncertainties and other errors that occur in experiments. Accuracy: –The extent to which a measurement agrees with the accepted value Precision: –The degree of exactness with which a quantity is measured

25. Observations, Facts, Inferences, and Hypotheses Observations: –The basis of science, may be made through any of the five senses or by instruments that measure beyond what we can see. Inference: –A generalization that arises from a set of observations. Fact: –When what is observed about a particular thing is agreed on by all or almost all.

26. Observations, Facts, Inferences, and Hypotheses Hypothesis: –An explanation set forth in a manner that can be tested and is capable of being disproved. Dependent variable: –A variable taken as the outcome of one or more variables. Independent variable: –The variable that is manipulated by the investigator; affects the dependent variable.

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28. Observations, Facts, Inferences, and Hypotheses Model: –A deliberately simplified explanation of complex phenomena. –Models are often physical Mathematical Pictorial or Computer-simulated

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30. Observations, Facts, Inferences, and Hypotheses Theories: –Models that offer broad, fundamental explanations of many observations

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32. Science, Pseudoscience, and Frontier Science Pseudoscience: –Some ideas presented as scientific are in fact not scientific, because they are untestable, lack empirical support, or are based on faulty reasoning or poor scientific methodology

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34. The Environment as a Commons Commons: –Land or another resources owned publicly with public access for private uses

35. Chapter 3: The Big Picture: Systems of Change

36. Systems A system is a set of components or parts that function together to act as a whole. –E.g. Body, city, river Open system- some energy or material moves into or out of system. Closed system- no such movements take place.

39. Feedback Feedback is when one part of the system changes –Those changes affect another part of the system –Which affects the first change Negative feedback- an increase in output leads to a later decrease. –Self-regulating, or stabilizing

40. Feedback Positive feedback- an increase in output leads to a further increase in the output. –Destabilizing Environmental damage can be especially serious when peoples use of the environment leads to positive feedback.

41. Positive Feedback

43. Feedback Some situations involve both + and – feedback. Human pop in large cities.

44. Stability A stable system is one that –Has a condition that it remains in unless disturbed. –Condition that it returns to if disturbed from it and the cause of the disturbance stops. Whether this is desirable depends on the system and potential changes.

45. Exponential Growth Growth occurring at a constant rate. –(rather than a constant amount) Plotted on a graph will form a J shaped curve

47. Exponential Growth Calculating EG involves two related factors –Rate of growth measured as a % –Doubling time in years Time necessary for the quantity being measured to double. EG is positive feedback and incompatible w/ sustainability

48. Environmental Unity It is impossible to change only one thing –Everything effects everything else Earth and its ecosystems are complex entities in which any action may have several or many effects.

49. Environmental Unity: An Urban Example Many midwestern US cities (i.e. Chicago) have had a shift in land use –Forest or ag land to urban development Construction increases runoff and soil erosion –Effects river channels and flood hazard After construction sediment load decreases but runoff still increases Thus land-use changes set off a series of changes which can trigger additional changes.

50. Environmental Unity: A Forest Example Forest, stream and fish in the Pacific Northwest Wood debris form and maintain pool environments in small stream. –Provide rearing habitat for young salmon –Formerly removed because thought to block fish migration Studying relations between physical and biological systems at the heart of enivor science

52. Uniformitarianism The physical and biological processes presently forming and modifying Earth are the same now as they were in the past. A study of past and present processes is key to the future.

54. Changes and Equilibrium in Systems Steady state –Input into a system equals output –No net change in the size of the reservoir –Dynamic equilibrium Because material entering and leaving the systems in equal amounts

55. Changes and Equilibrium in Systems When input is less than output –The size of reservoir declines When input is greater than output –The size of the reservoir increases

57. Changes and Equilibrium in Systems Average residence time- the time it takes for a given part of the total reservoir of a particular material to be cycled through the system. Large systems w/ a slow rate of transfer of water have a long residence time –Oceans –Difficult to clean up –Contrast to a stream w/ high rate of transfer

58. Earth and Life Earth formed 4.6 billion years ago Life began on Earth 3.5 billion years ago –Since life’s emergence many organisms have evolved, flourished, and become extinct. Humans to may some day become extinct. –Human activities increase and decrease the magnitude and frequency of natural processes. –Leading to many human caused extinctions.

59. Earth as a Living System Biota- all living things within a given area Biosphere- region of Earth where life exists –Also includes the system that sustains life All living things require energy and materials. –Energy from the sun and interior of Earth –Materials recycles through the system

60. Ecosystem A community of organisms and its local nonliving environment in which matter cycles and energy flows. Can be applied to different scales –Puddle to forest to planet –What is common to all is not physical structure but existence of processes –Can be natural or artificial

61. Gaia hypothesis The hypothesis states that life manipulates the environment for the maintenance of life. –Planet capable of physiological self-regulation Really a series of hypotheses –Life has greatly affected the planetary environment –Life has altered Earth’s enviro in ways that have allowed it to persist

62. Why Solving Environmental Problems Is Often Difficult 1. Exponential growth –The consequences of EG and its positive feedback can be dramatic, leading to incredible increases of what is being evaluated or measured.

63. Why Solving Environmental Problems Is Often Difficult 2. Lag time –The time between a stimulus and the response of a system. –Long lag time or delays may lead to overshot and collapse –Going beyond the carry capacity can lead to a collapse of a population.

65. Why Solving Environmental Problems Is Often Difficult 3. Irreversible consequences –Consequences that may not be easily rectified on a human scale of decades or a few hundred years.