A theoretical approach to the Suess effect

Abstract

From a theoretical study of the production and distribution of fossil-fuel carbon dioxide released since the beginning of the Industrial Revolution calculations have been made of the resultant decreases in atmospheric carbon-14 specific activities (Suess effect). The calculations are based on recent advances in the assessment of parameters which control carbon circulation and a re-evaluation of the combustion rates of fossil fuels. Results show that the reduction in carbon-14 specific activities amounted to -0.5, -3.2 and -5.9 % in A. D. 1890, 1950 and 1969 respectively. Analyses of biospheric materials of known age show good agreement between the predicted and observed atmospheric carbon -14 concentrations although the possibility exists of a perturbation of natural origin. The incorporation of significant amounts of fossil fuel carbon into 1890 wood indicates the possibility of error in radiocarbon analyses based on the conventional modern reference material. The study also enables corrections to be made for the Suess effect to observations of carbon -14 activities of samples grown during the past century. Predictions of future consumption of fossil fuels have permitted evaluation of the approximate magnitude of the future Suess effect. The results imply that the effect will be of increasing importance, reaching about -23% by 2000 and -50 % by 2025. The Suess effect, which is in competition with the nuclear bomb effect, may therefore reduce atmospheric carbon -14 concentration to the natural level again by 1990. Future increase in atmospheric carbon dioxide levels could have significant climatological consequences, but the magnitude of these changes remains speculative.