Exam2ReviewSheet - 1 Climate Change Evidence Why did we...

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1. Climate Change: Evidence Why did we focus on climate over the past ~400,000 years in our discussion of climate change? Continents and mountain ranges were much like they are today. Controls on climate should be similar, with human influence perhaps the difference. How do we learn about climate change over the past ~400,000? Drill cores into ice sheets to look at water and air in the atmosphere at the time the ice was deposited. Glacial versus interglacial periods during last ~400,000 yrs: What control’s the Earth’s temperature? Solar Heating Sunlight hits objects on Earth, they gain heat energy and radiate heat back out (similar to warmth off of an asphalt parking lot in the summer) Earth has a balanced “heat budget,” meaning heat in = heat out. Climate Forcing- events that change the heat balance, forcing the climate to change. Greenhouse Effect How does the greenhouse effect work? Some of the infrared radiation passes through the atmosphere but most is absorbed and re-emitted in all directions by greenhouse gas molecules and clouds. The effect of this is to warm the Earth’s surface and the lower atmosp What would global temperatures be with no greenhouse effect? Considering only solar input and re- radiation from the Earth’s surface, Earth would be between -30 and 16oF (-34 to -9oC). Greenhouse Gases (atmospheric CO 2 over time Which are greenhouse gases in the atmosphere? Water vapor, methane, CO2.nitrous oxide, ozone The most abundant =Water Vapor, then CO2. Where does CO2 come from? Natural CO2 Decaying organic matter Volcanic Eruptions Anthropogenic CO2 Burning fossil fuels Deforestation How have CO 2 concentrations changed over the past ~400,000 yrs? It’s increased What has been the range of CO 2 during that time? Why does the CO 2 concentration in the atmosphere change seasonally? Because of the trees in the summer. Energy Input from the Sun The Milankovitch Cycles Why do we have seasons of the year?
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  • Fall '11
  • FITZGERALD
  • Climate Change, CO2 emissions, Greenhouse gas, CO2 Direct Effect, Double CO2 Direct

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