We assumed that the tree-ring-based ¹³C/¹²C record constructed by Freyer and Belacy (1983) to be representative of the fossil fuel and forest-soil induced ¹³C/¹²C change for atmospheric CO₂. Through the use of a modification of the Oeschger et al. ocean model, we have computed the contribution of the combustion of coal, oil, and natural gas to this observed ¹³C/¹²C change. A large residual remains when the tree-ring-based record is corrected for the contribution of fossil fuel CO₂. A deconvolution was performed on this residual to determine the time history and magnitude of the forest-soil reservoir changes over the past 150 years. Several important conclusions were reached. (1) The magnitude of the integrated CO₂ input from these sources was about 1.6 times that from fossil fuels. (2) The forest-soil contribution reached a broad maximum centered at about 1900. (3) Over the 2 decade period covered by the Mauna Loa atmospheric CO₂content record, the input from forests and soils was about 30% that from fossil fuels. (4) The ¹³C/¹²C trend over the last 20 years was dominated by the input of fossil fuel CO₂. (5) The forest-soil release did not contribute significantly to the secular increase in atmospheric CO₂ observed over the last 20 years. (6) The pre-1850 atmospheric  values must have been in the range 245 to 270×10⁻⁶atmospheres.

Accelerator mass spectrometric radiocarbon measurements on benthic foraminifera shells, picked from samples on which concordant ages were obtained on the shells of two species of planktonic foraminifera, reveal that the age of deep water in the equatorial Atlantic during glacial time was 675±80 years (compared to today's age of 350 years) and that the age of deep water in the South China Sea was 1670±105 years (compared to today's value of 1600 years). These results demonstrate that the 1.3 to 1.5 times higher radiocarbon content of carbon in glacial surface waters of the Caribbean Sea reconstructed by Bard et al. [1990] was primarily the result of a higher global inventory of radiocarbon rather than a decrease in rate of mixing between surface and deep waters of the ocean. The results are also consistent with the conclusion by Boyle and Keigwin [1987] that the flow of North Atlantic Deep Water was considerably weakened during glacial time, allowing deep waters of Antarctic origin to push much further north into the Atlantic than they do today.