Movement among biotic and abiotic of the element that is most closely associated with the flow of energy.

The carbon cycle is a biogeochemical cycle that possess a , carbon dioxide, which is also its primary, immediately accessible mineralized form. Conversion of carbon to its organic form involves carbon fixing via, particularly, the Calvin cycle such as during photosynthesis.

Carbon is readily removed from the biosphere by burying, particularly of the remains of organisms, though the process itself occurs to substantial extents over . The resulting deposits range from to to , all of which are energy-rich organic forms of carbon, to , which is , an energy-poor form of carbon that is equivalent to and indeed derived from CO₂.

The carbon cycle is particularly relevant as we rapidly convert the above, stores of carbon back to carbon dioxide because of carbon dioxide's ability to .

The resulting contributes substantially to the warmth of the biosphere as well as more generally. Increasing carbon dioxide has the effect of preventing infrared light from as readily reaching . The consequence of this process, if allowed to progress , likely will be mass extinction, severe disruption of human , and in all likelihood catastrophic loss of life.