Develop a quantitative model to describe the cycling of carbon among the hydrosphere, atmosphere, geosphere, and biosphere.

The cycling of carbon through photosynthesis and respiration is only part of the global cycling of carbon. Geochemical processes also contribute to carbon cycling. Biological processes transfer carbon between organisms and the environment; geochemical processes transfer carbon between sedimentary rocks and the atmosphere, oceans and living organisms. Biological processes are relatively short term, occurring over years to hundreds of years while geochemical processes work on a time scale of millions of years. 

Carbon occurs primarily as carbon dioxide (CO2) in air and water, organic carbon (proteins, fats, carbohydrates, and nucleic acids) in living and dead organisms, and carbonate ions (CO3) in water, rocks, shells, and bones. To understand how these are connected in a cycle, it is useful to think in terms of reservoirs and fluxes. Reservoirs are where carbon is stored; fluxes are flows of carbon between reservoirs. 

Because carbon dioxide is a greenhouse gas, scientists are concerned that continued increases in atmospheric carbon may lead to global climate change. In this assessment, you will model the carbon reservoirs and fluxes and consider what might happen to the increasing carbon dioxide produced by human activities.