21.3 Climate Change
Natural Processes That
Change Climate
 Volcanic eruptions
 The presence of volcanic ash, dust, & aerosols in the air
increases the amt. of solar radiation that is reflected back
into space, causing Earth’s lower atmosphere to cool
 Ocean Circulation
 Also can result in short term fluctuations (El Nino)
 Solar Activity
 Short term change only, no evidence of long term
 Earth Motions
 Changes in the shape of Earth’s orbit & tilt are other Earth
motions that affect global climates
Human Impact on Climate
Change
 Greenhouse Effect
 A natural warming of both Earth’s lower atmosphere &
Earth’s surface
 CO2 & Water Vapor (major gases)
 Makes life as we know it possible
 Humans impact greatly
 Global Warming
 Increases in CO2 levels along with other greenhouse
gases, global temps. rise
 Warmer surface temps = increase evaporation rates =
increase amts. Of water vapor in atmosphere
 Ice melts
REVIEW REVIEW REVIEW
 What are the 4 natural processes that cause
climate change?
 What are possible effects of global warming?
 How may global warming affect Earth’s
inhabitants, including humans?
 What is the greenhouse effect?