This is a very simplified representation of the contemporary global carbon cycle from the report cover. See the companion figure, Components of the Global Carbon Cycle (alternate), for details about this natural flux between the terrestrial biosphere and the atmosphere and between the marine biosphere and the atmosphere.
Credit or Source: Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science. science.energy.gov/ber/
U.S. DOE. 2008. Carbon Cycling and Biosequestration: Report from the March 2008 Workshop, DOE/SC-108, U.S. Department of Energy Office of Science. (website)