The Carbon Cycle
All life is based on the element carbon. Carbon is the major element of most organic matter, from fossils to the complex molecules that control reproduction in organisms. Carbon is stored on our planet in the
major sinks as organic molecules in living and The dead organisms found in the biosphere. The gas carbon dioxide in the atmosphere, organic matter in soil, fossil fuels and sedimentary rock deposits in the lithosphere. The carbon cycle also helps keep the earth's temperature relatively stable by the balancement of carbon entering the atmosphere.
picture below: http://eo.ucar.edu/kids/green/images/carboncycle_sm.jpg