Global distributions of atmospheric carbon dioxide in the fossil-fuel era: a projection.

A model describing latitudinal mixing and accumulation of carbon dioxide in the atmosphere over the entire (projected) fossil-fuel era of human history but in the absence of climatic feedback is developed, including a new formulation of the oceanic sink term based on the tendency of atmospheric concentrations toward chemical and phase equilibrium with carbonic acid reactions in the deep oceans. For a “Gaussian” fuel consumption cycle wherein all potentially recoverable fossil reserves are eventually burned, the model predicts a doubling in global COz-above a pre-industrial level of approximately 300 ppm-by the year 2025. and a five-fold increase about 200 y from now. Some latitudinal asymmetry in ambient concentration was found to be generated by anthropogenic sources which predominate in the northern hemisphere at peak emission rates. At most, a difference of some 20ppm was predicted between the hemispheres, much less than the changes which can be induced in global-mean concentrations by fossil fuel burning over the coming century. While projected increases in CO* levels were found to be largely reversible within the next 10 y, they become increasingly less so as the carbonic acid equilibrium of the oceans is shifted. The qualitative effects of climatic feedbacks and the relationship of the present work to a more general model for climatic change are also discussed.