Begin by discussing the main question posed at the beginning of the section, “How do the activities of humans affect the environment on a continental and worldwide scale?” Relate the concept of population growth from the previous section to the effects humans have on the environment. Discuss the difference between the impacts that a small human population with little technology might have as compared to our current population and technology.
Define and discuss the term global change. Scientists now know that human activities are causing many natural systems of the environment to change. Make sure students know that many of the effects of human activities are indirect but nevertheless are supported by much scientific research.
After students have read about acid rain, assign What Do You Think? On page 63 as a discussion, debate, and/or writing prompt. Ask students to choose a policy decision concerning acid rain and defend it using evidence from the text.
Discuss the difference between global warming and the greenhouse effect. Then assign Activity 10-1: Feeling the Heat: The Greenhouse Effect as a hands-on way for students to see and explore the greenhouse effect in action. You can use student models and analyses of their models' accuracy as a method of assessment for this section.
What Do You Think?
How would you solve the problems caused by acid rain in the northeastern United States? Would your solution be fair to the people in the Midwest? Would it be fair to the people in the Northeast? Explain your reasoning.
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Suppose you found a water boatman, a salamander, and a mayfly while you were exploring a stream. What would you guess the pH of the stream would be? If you found only water boatmen in a second stream, would you guess that the second stream has a higher or lower pH than the first? (Hint: look at Figure 10.2 and make sure that you notice that the pH gets lower as you go up the vertical axis.)
Which of the effects of global warming do you think is more dangerous to humans-sea levels rising or rainfall patterns changing? Why? Should people who are not directly affected by these global warming effects do anything to decrease greenhouse gases? Why or why not?