Isotopic simple global carbon model: The use of carbon isotopes for model development

Carbon dioxide is a major greenhouse gas in the atmosphere. Anthropogenic CO{dollar}sb2{dollar} emissions from fossil fuel use and deforestation have perturbed the natural global carbon cycle. As a result, the atmospheric CO{dollar}sb2{dollar} concentration has rapidly increased, causing the potential for global warming.; A twenty four compartment isotopic simple global carbon model (ISGCM) has been developed for scenario analysis, research needs prioritization, and for recommending strategies to stabilize the atmospheric CO{dollar}sb2{dollar} level. CO{dollar}sb2{dollar} fertilization and temperature effects are included in the terrestrial biosphere, and the ocean includes inorganic chemistry which, with ocean water circulation, enables the calculation of time-variable oceanic carbon uptake.; The eight compartment simple global carbon model (SGCM) served as the basis of the ISGCM model development. Carbon isotopes, {dollar}sp{lcub}13{rcub}{dollar}C (stable carbon) and {dollar}sp{lcub}14{rcub}{dollar}C (radiocarbon), were used for model constraints as well as results from SGCM that led to multiple compartments in ISGCM.; ISGCM was calibrated with the observed CO{dollar}sb2{dollar} concentration, {dollar}deltasp{lcub}13{rcub}{dollar}C, and {dollar}Deltasp{lcub}14{rcub}{dollar}C in the atmosphere, {dollar}Deltasp{lcub}14{rcub}{dollar}C in the soil, and {dollar}deltasp{lcub}13{rcub}{dollar}C and {dollar}Deltasp{lcub}14{rcub}{dollar}C in the ocean. Also, ISGCM was constrained by literature values of oceanic carbon uptake (gas exchange) and CO{dollar}sb2{dollar} emissions from deforestation. Inputs (forcing functions in the model) were the CO{dollar}sb2{dollar} emissions from fossil fuel use and deforestation.; Scenario analysis, together with emission strategies tests, indicate that urgent action to reduce anthropogenic emissions would need to be taken to stabilize atmospheric CO{dollar}sb2{dollar}. Results showed that quantitatively, forest management is just as effective as the reduction of fossil fuel emissions in controlling atmospheric CO{dollar}sb2{dollar}.; Sensitivity analysis of temperature feedback suggests that future global warming would cause an additional perturbation in the global carbon cycle, resulting in depletion of soil organic carbon, accumulation of plant biomass, and the increase of atmospheric CO{dollar}sb2{dollar}.