(194a) Effects of Fossil Fuel Emissions and Seawater Absorption on Atmospheric Carbon Dioxide Concentrations

A differential equation δCO₂ = δE_f + 5.13 − 0.018CO₂ represents the increase in atmospheric carbon dioxide concentrations in any selected year between 1750 and 2015. In this equation δCO₂ is the increase in atmospheric carbon dioxide concentration, δE_f is the fossil fuel CO₂ emissions in ppm, and CO₂ is the atmospheric carbon dioxide concentration in January of the selected year. Although the equation was derived mathematically from published CO₂ data, the constants in the equation were verified by CO₂ seawater absorption and desorption experiments. Samples from the Pacific, Atlantic, Gulf of Mexico, North Sea, Baltic Sea, Black Sea and the St. Lawrence Seaway were tested in-situ and under laboratory conditions. The derivation of the equation, its experimental verification, and the relevance of CO₂ absorption by seawater to absorption by land-based biomass are discussed in this paper. The high degree of accuracy of the derived equation and the results of the CO₂ absorption experiments are consistent with the following conclusions. The CO₂ removal rate was a function of atmospheric CO₂ concentration, and neither the removal rate constant nor the effective absorption area changed between 1750 and 2015. The total annual rate of non-fossil fuel emissions not controlled by desorption kinetics, such as volcanic CO₂, was also constant. The annual fossil fuel CO₂ emissions rate was the only independent variable affecting atmospheric CO₂ concentrations, suggesting fossil fuel CO₂ was the primary cause of atmospheric CO₂ increases. Estimates of future atmospheric CO₂ concentrations were made for different fossil fuel emission rates assuming the equation remains valid. For example, atmospheric CO₂ could be reduced to 400ppm and maintained at 400ppm by reducing fossil fuel CO₂ emissions to 15Gt/year from approximately 35Gt/year. The longer the reduction in fossil fuel emissions is delayed the higher atmospheric CO₂ concentration will rise.