The global carbon cycle responds to multiple interacting factors including socioeconomics, the terrestrial, oceanic, atmospheric and climate systems. As such, the global carbon cycle may well be as important an indicator of global change as shifting temperatures and climate regimes. Atmospheric CO2 is exchanged rapidly with terrestrial and oceanic surfaces and it is the relative rates and strength of flux sources and sinks that determine the net atmospheric concentration of CO2.
Carbon is a fundamental building block with regard to terrestrial and oceanic productivity.
In addition, the rate of uptake of excess anthropogenic CO2 through the ocean's physical and biological pumps and terrestrial sequestration through the plant soil system are important drivers towards modulating atmospheric CO2 concentrations. The Earth's atmosphere therefore acts as the ultimate 'integrator' of carbon and energy fluxes from the land, ocean, and human ecosystems. Over the last 200-300 years, human numbers and activities have grown such that they have become a major force in driving biogeochemical cycles. Changes in the way human needs and preferences are met imply a reconsideration of the functioning of the global carbon cycle and necessitate co-operation between the social and natural sciences. For instance, terrestrial and oceanic productivity, energy, and information systems are global and deeply woven into local cultures and decision making.