1. The Environment Chapter 18 1

2. Human Population Growth Cause of other environmental problems Described by exponential growth model since 1650. 2

3. Human Population Growth 3

4. Since 1650 (population  500 million): – population doubled (to 1 billion) over the next 200 years. (1850s) – Doubled again to in 80 years (1930s) – took 45 years to reach 4 billion. (1975) – As of 2010 = 6.892 billion and is expected to reach exceed 8 billion by 2025. 4

5. Human Population Growth 5

6. Input (1) In your own words, write a statement that summarizes the main idea of the material just presented. 6

7. Output On the output page of you notebook respond to the following. Write your answer using one or more complete sentences. The current rate of human population is most similar to what population growth model ? 7

8. Human Population Growth An important demographic factor in the growth trends is a country’s age structure. – Age structure = the relative number of individuals of each age. Age-structure diagrams not only reveal a population’s growth trends, but also point to future social conditions. 8

9. Age Structure Diagrams 9

10. Based on the diagrams, we can predict that employment for an increasing number of working-age people will continue to be a significant problem for Kenya. In Italy and the U.S., a decreasing proportion of working-age people will soon be supporting an increasing population of retirees. In the U.S. it is this demographic feature that has made the future of Social Security and Medicare such a major political issue. 10

11. Input (2) In your own words, write a statement that summarizes the main idea of the material just presented. 11

12. Output On the output page of you notebook respond to the following. Write your answer using oone or more complete sentences. What is the age structure of a population? Why is it important? 12

13. Human Impact As the population grows: – People require more and more resources, – Energy requirement expand, – Pollution increases, and – Global Climate change may result. 13

14. The Atmosphere and Ecosystems Acid Rain 14

15. Atmosphere and Ecosystems Acid Rain Sulfur introduced into the atmosphere by smokestacks can combine with water vapor to produce sulfuric acid. The sulfuric acid is carried back to Earth’s surface as “acid” precipitation or acid rain. 15

16. Atmosphere and Ecosystems 16

17. Atmosphere and Ecosystems Acid Rain In the U.S. and Canada, thousands of lakes are “dying” as their pH levels fall below 5.0 Forests in the eastern U.S. and southern Canada are also being damaged. 17

18. 18

19. Atmosphere and Ecosystems 19

20. Input (3) In your own words, write a statement that summarizes the main idea of the material just presented. 20

21. Output On the output page of you notebook respond to the following. Write your answer using one or more complete sentences. What are the causes and effects of acid precipitation ecosystems? 21

22. The Ozone Layer The Ozone Hole In 1985, a researcher in Antarctica noticed that ozone levels in the atmosphere seemed to be as much as 35% lower than the average values during the 1960s. 22

23. The Ozone Layer Ozone “Hole” over Antarctica 23

24. The Ozone Layer The Ozone Hole Every year since then, more ozone has disappeared and the ozone hole has grown larger. Ozone blocks UV radiation from reaching Earth’s surface. In fact, in the U.S., the number of cases of malignant melanoma has almost doubled since 1980. 24

25. And premature wrinkling. 25

26. The Ozone Layer What is Destroying Ozone? Caused by chlorofluoro-carbons (CFCs). High in the atmosphere, UV radiation from the sun is able to break the usually stable bonds in CFCs. The resulting free chlorine atoms then react with and destroy ozone. Today many countries limit or ban the use of CFCs. 26

27. Input (4) In your own words, write a statement that summarizes the main idea(s) of the material just presented. 27

28. Output On the output page of you notebook respond to the following. Write your answer using one or more complete sentences. Why is ozone in the upper atmosphere important? What is the cause and effects of ozone depletion? 28

29. Global Temperatures Average global temperature has been increasing. In Earth ’ s long history there have been many such periods of global warming, often followed by centuries of cold. Some scientists suspect that human activity may be contributing to global warming. 29

30. Change in Global Temperature 30

31. Global Temperatures The Greenhouse Effect Carbon dioxide absorbs heat energy radiated from Earth’s surface This process, called the greenhouse effect, traps heat. There has been an increase in atmospheric carbon dioxide that seems to be related to the burning of fossil fuels and the clearing of forests. 31

32. The Greenhouse Effect 32

33. Global Temperatures Is Global Warming Occurring? The correlation of increasing global temperatures with increasing carbon dioxide levels is very close. In science, however, correlation does not prove cause and effect. Both global temperature and levels of greenhouse gases may be changing because of other variables that have not been recognized yet. However, many scientists are convinced temperature and carbon dioxide levels are related. 33

34. Atmospheric Temperature and CO 2 Levels 34

35. Input (5) In your own words, write a statement that summarizes the main idea of the material just presented. 35

36. Output On the output page of you notebook respond to the following. Write your answer using one or more complete sentences. What is the suspected cause of global warming? 36

37. Effects of Chemical Pollution One important urban environmental problem is chemical pollution. In a highly publicized example of pollution, a very large oil tanker ran aground off the coast of Alaska in 1989. Oil from the tanker heavily polluted 1,600 km (1,000 mi) of coastline and injured or killed thousands of marine animals. Many of the most disastrous incidents of pollution involve industrial chemicals that are toxic or carcinogenic (cancer-causing). 37

38. Effects of Chemical Pollution Agricultural Chemicals In many countries, modern agriculture introduces large amounts of chemicals into the global ecosystem. These chemicals include pesticides, herbicides, and fertilizers. Industrialized countries, like the United States, now attempt to carefully monitor side effects of these chemicals. 38

39. Effects of Chemical Pollution Agricultural Chemicals: Pesticides Molecules of chlorinated hydrocarbons — a class of compounds that includes the pesticides DDT, chlordane, lindane, and dieldrin — break down slowly in the environment. As these molecules pass up through the trophic levels of the food chain, they become increasingly concentrated. This process is called biological magnification. 39

40. Biological Magnification of DDT 40

41. Input 6) In your own words, write a statement that summarizes the main idea of the material just presented. 41

42. Output On the output page of you notebook respond to the following. Write your answer using one or more complete sentences. What is biological magnification? 42

43. Loss of Resources Habitat Destruction Another way that humans harm natural ecosystems is by physically altering the ecosystems. Through urbanization, human populations clear land or change water patterns to make way for building and roadways. 43

44. Loss of Resources Habitat Destruction Deforestation is where all the trees in a forest are completely cleared for the use of humans. The cleared land and wood from the trees can be used to grow food, build homes, or graze cattle. 44

45. Loss of Resources Species Extinction Habitat destruction contributes to species extinction. Earth is losing many species. Some 10 percent of well-known species teeter on the brink of extinction. Worst-case estimates are that we will lose up to one-fifth of the world ’ s species of plants and animals — about 1 million species — during the next 50 years. An extinction of this size has not occurred in at least 65 million years, since the end of the age of dinosaurs. 45

46. Loss of Resources Renewable vs. Nonrenewable Resources The trees that are cleared during deforestation are considered a renewable resource because they can produce new trees. If, however the trees are removed faster than they are replaced, the result is resource depletion. Nonrenewable resources, such as oil or coal may also be depleted because there is no known mechanism to replace them. 46

47. Sustainable Practices People can take steps to reduce their negative impact on the environment. In addition to governmental regulations aimed at reducing pollution, the choices of citizens and businesses may also impact the environment. 47

48. Sustainable Practices Things You Can Do Reduce, reuse, and recycle wastes Conserve energy – Use fuel efficient cars – Conserve electricity – Use public transportation, drive less 48

49. Review Which of the following types of energy is a renewable resource that humans can use? A.Minerals B.Coal C.Wind D.Natural gas 49

50. Review What effect does deforestation have on the carbon cycle? A.Decreased carbon in the atmosphere B.Increased carbon in the atmosphere C.Increased carbon in the oceans D.Decreased decomposition of carbon 50

51. Review Human activities that increase greenhouse gases in the atmosphere are likely to cause which of the following environmental changes? A.Decreased plant growth B.Tsunamis C.An ice age D.Global warming 51