Interannual variation of atmospheric CO sub(2) concentration

A method is described for the analysis of the interannual variability of background atmospheric carbon dioxide concentration. The analysis is carried out on the data from 6 observatories for which records of > 8 years were available. A global-scale interannual variation of CO sub(2) concentration in the troposphere with a characteristic time-scale of 2-3 years has been confirmed throughout the period of the records. These variations are estimated to be associated with carbon cycle imbalances of 2-3 Gt or annual net exchanges between the atmosphere and another carbon reservoir(s) at a rate of about 1.2 Gt of carbon per year. Lag correlations and amplitude comparisons between the records suggests a low latitude southern hemisphere origin to this phenomenon.