Atmospheric CO2: A 2-Box model accurately tracks 14C and 13C spanning 200 years and estimates global uptake of fossil fuel emissions

Abstract

Based upon a radically new approach, this paper describes a 2-box absolute flow model that calculates the CO2 transfer between the atmosphere and a terrestrial / ocean mixing reservoir. Given the inputs of anthropogenic fossil fuel emissions (CO2ff), atmospheric CO2 mixing-ratio and nuclear weapons bomb yields, the model calculates atmospheric 13C and Δ14C time-series, with the level of agreement for 13C being to within ± 0.05 ‰, for Δ14C to within ± 3‰, spanning 200 years. The model contains only seven internal parameters which are varied to optimize the fit. Yet according to conventional wisdom, this model should not work. It is commonly held that the 13C and 14C isotopic forms of carbon bypass seawater carbonate chemistry, resulting in very different absorption properties (Revelle factor) as compared to 12C. This study rejects this assumption, and uses the same residence time and reservoir mixing properties for all isotopes. The paper includes an analysis justifying why the isotopic bypass of the Revelle factor is not significant. The study describes the use of the model to track CO2ff takeup using two separate measures, a) the amount of molecular CO2ff remaining in the atmosphere and b) the amount of atmospheric growth attributable to CO2ff, thereby resolving discrepancies in published values.