1. Global Changes in the Atmosphere Pages 139-142

2. What is global warming? The gradual increase in the temperature of Earth’s atmosphere Over the last 120 years, the average temperature of the troposphere has increases 0.5 degrees Celsius

3. What is the greenhouse effect? The process by which gases in Earth’s atmosphere trap solar energy and keep the Earth warm Greenhouse Gases- water vapor, carbon dioxide & methane

4. What are some causes of global warming? Increasing greenhouse gases (especially CO2) What adds CO2 to the atmosphere? Human activities that add greenhouse gases to the atmosphere may be warming Earth’s atmosphere Burning of wood, coal, oil and natural gases add CO2 #1cause- motor vehicles

5. Another Hypothesis? Natural climate variations (a natural cycle caused by changes in solar output) Remember the ice age/interglacial periods?

6. Possible Effects Longer growing seasons in some areas and shorter growing seasons in others More evaporation drying out soil-> dust bowls More storms; not just hurricanes, but also winter storms Rising sea levels due to ice caps melting-> flooding

7. Ozone Depletion Chemicals produced by humans have been damaging the ozone layer Chlorofluorocarbons (CFCs)- complex chlorine compounds found to destroy ozone molecules Found in air conditioner and refrigerator coolants, some cleaners and spray cans

8. Impacts of ozone depletion More UV rays reaching the surface and causing more eye and skin damage

9. What is being done? In the late 1970’s 196 countries joined the Montreal Protocol agreeing to discontinue the use of CFCs in spray cans.

10. Figure 21

11. The Scientific Assessment of Ozone Depletion 2010 report said a 1987 international treaty that phased out chlorofluorocarbons (CFC) - substances used in refrigerators, aerosol sprays and some packing foams - had been successful.