Copyright Pearson Prentice Hall Biology Copyright Pearson Prentice Hall

6-4 Charting a Course for the Future Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ozone Depletion What are two types of global change of concern to biologists? Copyright Pearson Prentice Hall

6-4 Charting a Course for the Future Researchers are gathering data to monitor and evaluate the effects of human activities on important systems in the biosphere. Two of these systems are: the ozone layer high in the atmosphere the global climate system Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ozone Depletion Exposure to UV can: cause cancer damage eyes decrease organisms' resistance to disease damage plant leaf tissue and phytoplankton in the oceans Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ozone Depletion Early Evidence In the 1970s, scientists discovered a hole in the ozone layer over Antarctica. After it was first discovered, the ozone hole grew larger. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ozone Depletion One Solution CFCs (chlorofluorocarbons) were once widely used: as propellants in aerosol cans as coolant in refrigerators, freezers, and air conditioners in the production of plastic foams The U.S. and other nations began reducing the use of CFCs in 1987, and eventually banned them. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ozone Depletion Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Global Climate Change Global Climate Change The term used to describe the increase in the average temperature of the biosphere is global warming. One sign of global warming is melting polar ice. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Global Climate Change Biologists are concerned about global warming. This map of the Arctic is based on images taken by satellites in 1979 and 1999. Sea ice in the Arctic Ocean has receded so quickly that some scientists suggest that, within the next 50 years, the ice could disappear completely. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Global Climate Change Evidence of Global Warming The geological record shows that Earth’s climate has changed repeatedly during its history. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall

The Value of a Healthy Biosphere Human society depends on healthy, diverse, and productive ecosystems because of the environmental and economic benefits they provide. Copyright Pearson Prentice Hall

The Value of a Healthy Biosphere Human society depends on healthy, diverse, and productive ecosystems because of the environmental and economic benefits they provide. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 6-4 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 6-4 An increase in the average temperature of the biosphere is called the greenhouse effect. global warming. ozone depletion. climate control. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 6-4 The geological record indicates that Earth’s climate has remained essentially the same throughout history. been constant until humans have influenced the environment. changed dramatically every 150 years. repeatedly changed over its history. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 6-4 A possible effect of global warming is extinction of organisms in areas where they once thrived. an increase in global surface temperature of 20 Celsius degrees. a sharp decrease in the temperature of the waters off the coast of California. complete elimination of the protective ozone layer in the atmosphere. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 6-4 Depletion of Earth’s protective ozone layer results in a decrease in the amount of heat that reaches the surface. a decrease in the amount of UV radiation that reaches the surface. an increase in the amount of rainfall. an increase in the amount of UV radiation that reaches the surface. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 6-4 The most likely cause of ozone depletion is the addition of carbon dioxide to the atmosphere. increase in UV radiation from the sun. addition of chemicals developed for use in refrigeration and aerosol cans. increase in the amount of smog produced by automobiles. Copyright Pearson Prentice Hall

END OF SECTION