All carbon cycle models referenced by the IPCC have a common feature: Increased carbon dioxide in the atmosphere originates from anthropogenic emissions. It is also generally known that the CO2 concentration observations show that about 44 – 46 % of yearly CO2 emissions seem to have accumulated in the atmosphere; the ocean and biosphere take up the rest. Therefore, this straightforward conclusion that the increased atmospheric CO2 is anthropogenic may seem correct, but there are profound physical problems. An unusual feature is among carbon budget presentations, that they do not calculate the isotopic composition of the atmospheric CO2 nor refer to the observed global d13C used as a measure of isotopes 13C/12C ratio from 1750 to the present time. The analyses of this study show that the current d13C value of -8.6 ‰ in the atmosphere conflicts with physical processes and applied recycling flux values meaning that the increased atmospheric CO2 since 1750 cannot be exclusively anthropogenic. This study’s atmospheric anthropogenic CO2 amount of 70 GtC is much smaller than the 279 GtC reported by the IPCC for 2019. Also, the removal rate of anthropogenic CO2 from the atmosphere can be approximated to be about 64 years — the same as the radiocarbon 14C removal rate after the 1964 nuclear tests corresponding to the e-folding time of 11 years. The total CO2 removal rate would be about 220 years meaning an e-folding time of 38 years.
Continue reading: Testing Carbon Cycle Models and Budgets by Antero Ollila.