The carbon pool sizes in the boxes are expressed in Gt C (Gt C = 10^15 g C). Annual increments expressed in Gt C per year are shown in parentheses. All fluxes indicated by the arrows are expressed in Gt C per year. The inferred net terrestrial uptake of 0.7 Gt C per year considers gross primary production (~101.5), plant respiration (~50), decomposition (~50), and additional removal from the atmosphere directly or indirectly, through vegetation and soil and eventual flow to the ocean through the terrestrial processes of weathering, erosion, and runoff (~0.8). Net ocean uptake (~1.6) considers air/sea exchange (~92.4 gross uptake, -90.8 gross release). As the rate of fossil fuel burning increases and CO2 released to the atmosphere it is expected that the fraction of this C remaining in the atmosphere will increase resulting in a doubling or tripling of the atmospheric amount in the coming century.