carbon cycle

Sequence of processes through which carbon compounds move from one carbon reservoir or sink (such as forests and oceans) to another (such as atmosphere) and back. Since more carbon dioxide is being released into the atmosphere through the burning of fossil fuels and less is being 'fixed' (converted into organic compounds through photosynthesis by plants) because of the destruction of tropical forests, the carbon cycle is in danger or being severely disrupted. International accords such as Kyoto protocol are trying to limit the production of carbon dioxide (and other greenhouse gases) through the imposition of emission controls.