1. Chapter 4 Section 4 Global Changes in the Atmosphere

2. OBJECTIVE: Investigate current issues concerning climate change 1.El Nino & La Nina are short-term changes in the tropical Pacific Ocean caused by changes in ocean surface currents and prevailing winds. Both influence weather patterns world-wide. *El Nino causes the surface of the ocean in the eastern Pacific to be unusually warm. *La Nina causes the surface of the ocean in the eastern Pacific to be colder than normal. 2. Global Warming: The gradual increase in the temperature of Earth’s atmosphere.

3. *Greenhouse Gases Hypothesis: Human activities that add greenhouse gases to the atmosphere may be warming Earth’s atmosphere. *Changing Levels of Carbon Dioxide: An increase in Carbon Dioxide may be a major factor in global warming. *Climate Variations Hypothesis: The amount of energy the sun produces increases and decreases from year to year. *Possible Effects: Farmers in some areas that are now cool could plant two crops per year instead of one. Higher temps could cause dust bowls like in the 1930’s. Warmer ocean temps could increase the strength of Hurricanes.

4. As water warms, it would expand, raising sea levels. Melting glaciers and polar ice caps could increase sea levels. This would cause flooding of low-lying coastal areas. 3. Ozone Depletion: Chemicals produced by humans have been damaging the ozone layer. *Chlorofluorocarbons: (CFC’s) Used in air conditioners, Refrigerators, cleaners, and aerosol sprays. *Results of Ozone Depletion: An increase in UV radiation that reaches Earth’s surface. Worldwide production of CFC’s has greatly decreased. The ozone hole is expected to gradually shrink over time.