Concentrations of carbontetrafluoride (CF4) observed at the south pole suggest that this inert trace gas is accumulating in the earth's atmosphere at about 1.3 (0.8--2) pptv/yr. This amounts to an average increase of about 1.8 (1--3)¿1010 gms/yr and can be explained by the estimated emissions of CF4 from aluminum manufacturing. Although it is still not possible to determine how much, if any, of the present atmospheric content of CF4 is from natural sources, it appears that these sources are small (≤109 gm/yr) and therefore will be extremely difficult to identify and evaluate.