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?