Analysis of CO2 residence times suggest 65% to 96.5% of the CO2 concentration increase since 1958 is natural.
According to a new study, the claim that increases in atmospheric CO2 are driven exclusively by humans relies on a made-up, disparate accounting model, with the residence time for natural emissions 3 to 4 years (which is consistent with actual observations), but CO2 from human sources is claimed to have a residence time of 50 to over 100 years.
The 15 to 30 times longer residence time for human emissions is an imaginary conceptualization that is wholly inconsistent with (1) bomb tests (1963) and (2) seasonal CO2 variations found in real-world observations.
Human emissions account for under 5% of the total from all sources, natural and anthropogenic. Nature’s sinks do not decide which CO2 to absorb, depending on the source. Absorption is instead proportional to the source.
Consequently, Dr. Harde insists that a “comprehensive analysis and reproduction of the atmospheric CO2 evolution requires to…treat all emissions in a consistent manner.”
When the imaginary-world 50-100+ years residence time for anthropogenic CO2 accounting method is not used, and instead natural emissions and human emissions are treated as equal (both with a residence time under 10 years), the attribution for the CO2 increase falls to as little as 3.5%, with the upper limit 35%.
Image Source: Harde, 2023a
Ferdinand Engelbeen, a long-time proponent of the position that humans are 100% responsible for CO2 concentration changes, published a Comment in the same journal, replying to the above study. Engelbeen claims natural emissions are always 100% balanced by natural sinks, and “there is zero contribution from natural sources and sinks to the increase in the atmosphere.”
Dr. Harde then published a Reply to Engelbeen, explaining that his position employs “circular reasoning,” and that the assumption that nature contributes zero to CO2 concentration change is “nonsense and misses any scientific basis.”
Harde further explains that treating the residence of CO2 as equal for anthropogenic and natural emissions allows for the conclusion that natural emissions add 31.2 ppm/year to the increase, whereas humans add 5.5 ppm/year. The natural contribution to the CO2 increase since 1958 is thus nearly 6 times greater than that from humans.