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18.4 Global changes in the atmosphere Page 641. Key concepts: What events can cause short-term climate changes? How might human activities be affecting the temperature of Earth’s atmosphere? How have human activities affected the ozone layer?
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18.4 Global changes in the atmosphere Page 641 • Key concepts: What events can cause short-term climate changes? How might human activities be affecting the temperature of Earth’s atmosphere? How have human activities affected the ozone layer? • Key terms: El Nino, La Nina, global warming, greenhouse gas, chlorofluorocarbon
Short-term climate changes • El Nino and La Nina are short-term climate changes in the tropical Pacific ocean caused by changes in ocean surface currents and prevailing winds. • El Nino – warm-water event begins when an unusual pattern of winds forms over the western Pacific. It cases the surface to be unusually warm. • La Nina – when the water is colder than usual. The opposite of El Nino. Brings colder weather.
Global warming • Gradual increase in the temperature of Earth’s atmosphere. • Greenhouse hypothesis – human activities add greenhouse gases and warm the atmosphere
Changing levels of Carbon dioxide • Increase in carbon dioxide in the atmosphere • Checked against air bubbles caught in Antarctic ice
Climate variation hypothesis • Some scientists think the rising temperatures are due to natural variations in climate
Possible effects • Global warming could have some positive effects • Maybe. Not really. I can’t imagine that and your book is a little vague on it.
Ozone depletion • Ozone filters out UV rays. • Chemicals produced by humans have been damaging it for years • Chlorofluorocarbons – compounds (CFCs) that were used in air conditioners and aerosol sprays
Result of ozone depletion • Increase in UV rays – eye damage, cancer