Lab 12 - Global Warming - GEOL 1404 Historical Geology Lab...

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GEOL 1404 Historical Geology Lab Spring 2009 Global Warming Name: _________________________________ The Carbon Cycle Carbon passes between reservoirs in a wide range of biological, geological, and chemical processes collectively known as the carbon cycle. Living organisms on Earth, for example, represent one reservoir of carbon. In the atmosphere carbon exists in the form of the odorless, colorless gas carbon dioxide. Photosynthetic organisms take up carbon dioxide during photosynthesis and use the carbon to build their cells. The photosynthesizers most important to the global carbon budget are trees in the northern hemisphere and phytoplankton in the oceans. Animals and other heterotrophs get carbon to build their cells by consuming either photosynthesizers or other consumers. They return carbon to the atmosphere by respiring. When organisms die they pass carbon on to life forms like bacteria, which also return carbon to the atmosphere by respiration. This process is called decomposition . If dead matter is buried before it can be decomposed its carbon will eventually be stored in the Earth’s crust as coal, oil, natural gas, etc. Some living things in the oceans make their shells of calcium carbonate, and when they die their shells can accumulate and store carbon as limestone. Limestone also forms inorganically by precipitation of calcium carbonate in the oceans. Rock weathering is an extremely slow process but one that is important to the carbon cycle over geologic time. Rocks are chemically weathered by slightly acidic rainwater that dissolves small amounts of the rock. Rainwater is slightly acidic because of small amounts of carbonic acid in the clouds. Carbonic acid is supplied by carbon dioxide in the atmosphere. The only natural way rocks containing carbon re-enter the carbon cycle is by being exposed and weathered. If they are exposed it is by tectonic movements which necessarily take a very long time. Organic carbon in the Earth’s crust also happens to be an excellent chemical fuel, and so it is brought to the surface by humans as well. By combustion , humans utilize the energy in fossil fuels and emit carbon dioxide. Humans make modifications in the carbon cycle by land use changes as well. By clearing large plots of land they deter the land’s ability to absorb carbon dioxide (fewer trees). If the land is used for agriculture other plants are put in place, but the added biomass becomes a reservoir for another carbon gas, methane. If the land is used for a place to breed livestock , the greater number of cows produces a greater amount of methane. 1
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1) Label the following diagram using key words (in bold) from the text above. Figure 1 : Simplified diagram illustrating the Carbon Cycle. Phanerozoic trends in carbon dioxide
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This note was uploaded on 03/27/2012 for the course GEOL 2413 taught by Professor Moody during the Spring '10 term at Texas A&M University, Corpus Christi.

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Lab 12 - Global Warming - GEOL 1404 Historical Geology Lab...

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