Using the Suess effect on the stable carbon isotope to distinguish the future from the past in radiocarbon

The depletion of C-14 due to the emission of radiocarbon-free fossil fuels (C-14 Suess effect) might lead to similar values in future and past radiocarbon signatures potentially introducing ambiguity in dating. I here test if a similar impact on the stable carbon isotope via the C-13 Suess effect might help to distinguish between ancient and future carbon sources. To analyze a wide range of possibilities, I add to future emission scenarios carbon dioxide reduction (CDR) mechanisms, which partly enhance the depletion of atmospheric Delta C-14 already caused by the C-14 Suess effect. The C-13 Suess effect leads to unprecedented depletion in delta C-13 shifting the carbon cycle to a phase space in Delta C-14-delta C-13, in which the system has not been during the last 50 000 years and therefore the similarity in past and future Delta C-14 (the ambiguity in C-14 dating) induced by fossil fuels can in most cases be overcome by analyzing C-13. Only for slow changing reservoirs (e.g. deep Indo-Pacific Ocean) or when CDR scenarios are dominated by bioenergy with capture and storage the effect of anthropogenic activities on C-13 does not unequivocally identify between past and future carbon cycle changes.