Sources for this text are emails between Erik Bye, physical chemist in Oslo, Norway, and various members and associates of the CO2 Coalition.
Any person mentioned in this document can email John Shanahan at acorncreek2006@gmail.com and have their respectfully worded comments added.
Erik Bye
July 22, 2025
https://co2coalition.org/wp-content/uploads/2024/12/HumanContribution-to-Atmospheric-CO2-digital-compressed.pdf
Ferdinand Engelbeen, sent me the following mail:
«Dear Erik Bye,
I don't think that the CO2 Coalition is wrong about natural CO2 emissions: these are hardly mentioned at all in our work because these are completely irrelevant…
Human emissions are one-way into the atmosphere for 100%, thus add every single CO2 molecule directly into the atmosphere.
Natural emissions are more than fully compensated by natural sinks in such a way that natural sinks are larger than natural sources, thus nature is a net sink for CO2, not a net source and can't be the cause of the increase in the atmosphere...
Our work is not about CO2's central position in the food chain, but a work that shows all evidence why our CO2 (and not natural CO2) is the cause of the recent increase of CO2 in the atmosphere.
…
Ole Humlum is wrong about his contribution of human emissions, because the dent in human emissions during one year (2020) was only 10% of the "normal" emissions: 4.1 ppmv i.s.o. 4.8 ppmv. The increase in the atmosphere still was 2.3 ppmv that year, thus fully caused by the 4.5 ppmv human emissions. Temperature caused natural variability (+/- 1.5 ppmv/year) is a variability in net sink rate, not net source rate!»
My comments:
«The Coalition excludes the natural emission from the budget, because this is said to be irrelevant. And, in addition to the calculation of Harde (15% human contribution), also Ole Humlum is wrong in his CO2-emission considerations.
In the budget, Engelbeen verifies that the human contribution is only 5% whereas the natural part is 95%. This is in full agreement with the findings of Segalstad (1992), and he gives no explanation for such a dramatic change in the flux-direction for the natural CO2-emissions from «old» to «modern» time.»
His comment about Ole Humlum is related to my reference to Humlum's Climate4you, where Humlum states:
«5. There is no perceptible effect on atmospheric CO2 due to the COVIDrelated drop in GHG emissions 2020-2021, demonstrating that natural sinks and sources for atmospheric CO2 far outweigh human contributions. Therefore, any future reductions in the use of fossil fuels are unlikely to have any significant effect on the amount of atmospheric CO2.»
Here, Humlum supports my opinion; there is no dramatic change in the composition of the CO2 emission.»
My answer:
Dear Ferdinand Engelbeen,
Thank you for your response to my viewpoints, regarding the emissions of CO2 during modern times.
However, I am convinced that the Coalition is wrong about the statement in the ABSTRACT, listed above.
You write «. . that the modern increase in CO2 is mainly due to anthropogenic emissions». It is a failure to omit the emission of natural CO2, and I find it difficult to accept that the natural CO2 is irrelevant, as you underline in this mail.
I suppose that we can agree about the residence time of about 4 years for CO2. That means that a 1/4 of the total amount of CO2 in the atmosphere is exchanged each year. After 4 years the total amount of the CO2 content is exchanged. Thus, for each year, 1/4 of the total amount is substituted, through the emission of a corresponding amount of a similar CO2-mixture into the atmosphere.
There is only one way to substitute the exchanged CO2, and that is by the emission of a corresponding amount. In this way, the ratio between the natural and the anthropogenic amount of CO2 is perserved.
On the contrary, how do you explain the present level of CO2 in the atmosphere, with a residence time of 4 years, and mainly emission of anthropogenic CO2 in modern times? In particular if the anthropogenic content is only 15%, as documented by Harde (2023):
https://scienceofclimatechange.org/wp-content/uploads/Harde-2023Understanding-Increasing-CO2-II.pdf
Erik Bye
Then I asked him:
Would an investigation similar to the one Segalstad carried out in 1992 give the final answer to this question? In this case I think that observations will rule over your theoretical considerations.
A surprising lack of knowledge of the work of Segalstad was clearly demonstrated in the next mail:
«Erik, what experiment? All that I could find is his comment, rejecting CO2 measurements in ice core and atmosphere, completely at odds with the scientific knowledge of already that time and completely nonsense with the knowledge of today.
He may not like the CO2 data of today, but these are collected worldwide by lots of people in several different organizations in different countries. Cheating with the CO2 data would be impossible without one whistleblower in 67 years?
And not at least: he doesn't understand the difference between the residence time of around 4 years (where everybody agrees, even the IPCC) and the "adjustment" time, which is observed (yes observed...) of around 50 years.
The IPCC also is wrong with their modeled removal rates for part of the CO2 increase of hundreds to thousands of years, but that is not the point here. The point is that human emissions as CO2 mass (not the original molecules alone) aren't removed in 4 years. That takes 50 years to reduce the excess mass of CO2 to 1/e of the original release. That is what Segalstad doesn't accept, any of other points of evidence...»
My comment:
«I did not find it opportune to start a discussion on the work and considerations made by Tom Segalstad. Particularly since he was not aware of the actual experiment.»
My next question:
Are you not familiar with the determination of 4% fossil CO2 by Tom?,
He responded:
«No, couldn't find that on the Internet, only his comment on the ice core and atmospheric CO2 measurements, which were completely at odds with reality then and certainly now.
Even if he did find 4% fossil CO2 in the atmosphere at that time, which can be right, that only proves that remaining fossil CO2 molecules in the atmosphere were 4%, not that the increase in the atmosphere was only for 4% caused by fossil fuels... Because already a (large) part of fossil CO2 molecules were exchanged with CO2 molecules of other reservoirs (oceans, vegetation), where the rest of the fossil molecules now reside. The full increase in CO2 mass/level still is from the one-way addition of fossil CO2...»
My comment:
«This is a big surprise for me. Ferdinand had contact with Segalstad earlier, but doesn't know about one of his most fundamental works? The world operates with fossil fuel about 4%, due to the work of Segalstad. This might be an indication of a limited literature work of the Coalition.
Another interesting detail in this discussion: As long as I was a member of the Coalition, I asked about the same. What about a new experiment, copying the work of Segalstad! I got questions like: what kind of experiments are you thinking of? What do you expect to get out of an
experiment?
Obviously, the Coalition is most familiar with models and theoretical speculations. They were not thinking of evidence. And nobody was familiar with the experiments of Segalstad (1992)»
Then I referred to the use of AI.
«A colleague of mine asked GROK about the emissions of CO2 (GT) to the atmosphere. The answer was not surprising to me, related to the IPCC reports: AR4 AR6
801 879 Human 29 45
The total amount increased by 78 GT, the anthropogenic part with only 16 GT. That means approximately 5 times more of the natural part.
I dont think it is feasible to talk about «confusion» any more. Until we can refer to new observational data, I will claim that the Coalition is wrong.
Regards
Erik»
Then Ferdinand just repeated his viewpoints:
«Erik,
Nobody disputes that human emissions are only a small part of the total emissions.
In 1960 only 1.5%
In 2020 only 4.5%
The problem with your (and Segalstad's, Harde, Berry,...) reasoning is that the carbon balance besides incoming CO2, also has outgoing CO2 and that is what is forgotten by them all...»
This time I just referred to his last sentence:
«Based on your first sentence:
«Erik,
Nobody disputes that human emissions are only a small part of the total emissions.»,
Thanks for this clarification.»
I then sent him the article of Tom Segalstad.
He responded:
«Erik,
Thanks for the paper, but
Meanwhile, the percentage of fossil CO2 is over 10% in the atmosphere, while only 1.5% to 4.5% (1960-2020) in the inputs and over 6 % in the ocean surface, and increasing in plants and deep oceans (but difficult to measure there).»
Then two details had to be clarified:
«Does this mean that you conclude that the total amount of CO2 in the atmosphere is not exchanged within about 4 years? If so, what is the exchange time?»
and:
«Ferdinand, this process of yours is complicated. If you want a follow-up for your comments to the paper of Tom, I suggest that you do this with him.»
At this time, I felt the discussion didn’t give more principal information. We exchanged some more emails, without any particular values to be reported here.
My Conclusion is that we would have been much better off with new experiments, to bring new real events into this discussion, and not being linked to the theoretical considerations from The Coalition.