Knorr found the airborne fraction [AF] of ACO2 has not changed in 150 years. The AF is the % of ACO2 emissions which remain in the atmosphere contributing to the increase in atmospheric CO2 levels. The constant AF found by Knorr was about 40%.
Figure 1 from Knorr illustrates this:
Knorr describes Figure 1 as "Observed atmospheric CO2 increase derived from direct measurements, taking the average of Mauna Loa (Hawaii) and the South Pole (thin solid line), and two ice cores: Law Dome (dashed thin line) and Siple (dotted thin line). This is compared to total anthropogenic emissions (thick solid line) and 46% of total emissions (thick dashed line)".
The 46% in fact was an estimate by Dr Knorr [as indicated in private correspondence] and should be 40% as the calculated amount of the constant AF. The graph shows that general atmospheric CO2 is increasing by much less than the amount of the ACO2 emissions. It is this which underpins the argument that ACO2 is responsible for all the increase in atmospheric CO2. That is, given the assumption that natural emissions and sinks were in equilibrium before ACO2 started to increase, the official position is now that the sinks have increased to absorb some of the increase in ACO2 but not all and that remainder of non-absorbed ACO2 is what is causing the increase in atmospheric CO2.
Quirk and the stomata history has already shown that the assumption that natural CO2 emissions and sinks were in equilibrium is problematic. What the constant AF shows is that the increase in ACO2 and natural sinks does not explain the increase in atmospheric CO2. The AF does this because it is the ONLY amount of ACO2 available to increase the atmospheric CO2. The expanding sinks are absorbing about 60% of the increase in ACO2 but as Knorr's figure 1 plainly shows atmospheric CO2 increase is expanding more than the remaining 40% of ACO2 left. This is shown by all the peaks above the thick dashed line. If the AF were graphed at its correct 40% it would be slightly lower than shown in Knorr's graph. This is plainly shown in this graph based on the Mauna Loa measurements from 1959:
Graph by Ian Hill
Clearly the AF is predominantly below the yearly increase in atmospheric CO2. This is reflected in a comparison between the slopes of the increase atmospheric CO2 which is 0.0575 and the AF which is 40% of the increase in ACO2, or 0.0447. That is, the AF is increasing LESS than the increase in atmospheric CO2. Even in those years when the increase falls below the AF it cannot be said that natural CO2 emissions are not contributing because of the lack of equilibrium between CO2 emissions and sinks.
The effect can be compared with the principle of a constant in an increasing total: say ACO2 is 40% of all CO2 [as per the constant ACO2 AF] which is 100, so ACO2 is 40 and natural CO2 is 60; when all CO2 is 200 ACO2′s 40% will be 80 so natural CO2 will be 120, an increase of 60; at 300, ACO2 is 120, natural CO2 is 180 and so on; natural CO2 MUST be contributing to the increase in total CO2.
Man made global warming [AGW] is based on human emissions of CO2 disrupting the climate. The basic science supporting AGW has been shown to be defective. If it turns out that human emissions of CO2 are not the primary reason for the increase in atmospheric CO2 then even further doubt is cast on the theory of AGW.