In the biosphere, a set of cycles represents how energy and elements flow from one component, like the atmosphere, to others where they are accumulated (permanently of temporarily) or passed on. Carbon, nitrogen and water cycles are the most significant.
The above figure illustrates the potential contribution of human activities, including transportation, to different geographical scales of the carbon cycle. This investigation of the anthropogenic contribution of emissions to the atmosphere may reveal only one link in the environmental chain. Further, several aspects of the carbon cycle are ill-defined and difficult to evaluate, but show all the complexity the growth of carbon dioxide emitted by transportation may imply for elements of the environmental system, including the atmosphere, the lithosphere, the hydrosphere and the ecosphere.