Modeling of atmospheric carbon dioxide (CO2) concentrations as a function of fossil-fuel and land-use change CO2 emissions coupled with oceanic and terrestrial sequestration

Abstract

In this work, a semi-empirical relationship of carbon dioxide emissions with atmospheric CO2 concentrations has been developed that is capable of closely replicating observations from 1751 to 2018. The analysis was completed using data from fossil-fuel-based and land-use change based CO2 emissions, both singly and together. Evaluation of emissions data from 1750 to 1890 yields a linear CO2 concentration component that may be attributed to the net flux from land-use changes combined with a rapidly varying component of the terrestrial sink. This linear component is then coupled across the full-time period with a CO2 concentration calculation using fossil-fuel combustion/cement production emissions with a single, fixed fossil-fuel combustion airborne fraction [AFFF] value that is determined by the ocean sink coupled with the remaining slowly varying component of the land sink. The analysis of the data shows that AFFF has remained constant at 51.3% over the past 268 years. However, considering the broad range of variables including emission and sink processes influencing the climate, it may not be expected that a single value for AFFF would accurately reproduce the measured changes in CO2 concentrations during the industrial era.