Something left unsaid about Koutsoyiannis et al.
October 22, 2023The TL:DR
The remaining real-world case study led to an important side product of the current research. This is the surprising finding that, while in general the causal relationship of atmospheric T and CO₂ concentration, as obtained by proxy data, appears to be of hen-oregg type with principal direction 𝑇 → [CO₂], in the recent decades the more accurate modern data support a conclusion that this principal direction has become exclusive
We know from measurements that more CO2 is being emitted by burning fossil fuels than remains in the atmosphere. We also have measurements showing that ~105 _+ 8 Pg C from these emissions has been absorbed in the oceans* and the biosphere has i** and we have measurements and theory on how temperature and salinity affect CO2 partial pressure in the gas phase above sea water*** where a difference of 1C corresponds at best to a few ppm.
Of course we know that the atmospheric concentration of CO2 has increased from ~290 to ~430 ppm over the last 150 years.
This poses some obvious problems for any statistical treatment which claims that CO2 concentration follows changes in temperature
*Feely, R. A., Sabine, C. L., Takahashi, T., & Wanninkhof, R. (2001). Uptake and storage of carbon dioxide in the ocean: The global co~ 2 survey. OCEANOGRAPHY-WASHINGTON DC-OCEANOGRAPHY SOCIETY-, 14(4), 18-32.
**Amthor, Jeffrey S. “Terrestrial higher‐plant response to increasing atmospheric [CO2] in relation to the global carbon cycle.” Global Change Biology 1.4 (1995): 243-274 and especially the annual cycle
***Weiss, R. F., Jahnke, R. A., & Keeling, C. D. (1982). Seasonal effects of temperature and salinity on the partial pressure of CO2 in seawater. Nature, 300(5892), 511-513
From the information in [1] we can therefore draw a second conclusion: For timescales in multiple decades, the results in figure 14 have no meaning since the data span a far too short time. The differentiation has also suppressed slow changes. Common perception that [CO2] causes an increase in the temperature can thus neither be verified nor falsified. It is self-evident that the effect ΔT → [CO2], which is seen on a short timescale, will also be present on all longer timescales. A temperature change in the order of 0.4°C will cause a change in [CO2] of about 2 ppm, as measured on the derivatives.3 The temperature change over the 42 years is about 0.5°C while [CO2] has changed by about 80 ppm. Some other mechanism is likely to dominate on timescales of multiple decades. Hence, the common perception that increasing [CO2] causes increased T seems likely. . . . .
Settled science’ is supported by many lines of evidence and it includes many more factors than [CO2] as causes of the increased temperature since pre-industrial times. CO2 is however considered to be the largest factor. ‘Settled science’ includes the phenomenon that increased T causes a modest increase of [CO2] (outgassing from the sea), which is detected in [1]. The statement ‘in the recent decades the more accurate modern data support a conclusion that this principal direction has become exclusive. In other words, it is the increase of temperature that caused increased CO2 concentration’ that appears in Discussion and conclusions in [1] is not supported by proper arguments in the paper.https://royalsocietypublishing.org/doi/10.1098/rspa.2022.0529
This comment is notable for two things, all the references are to websites (inc. Roy Spencer’s blog) and there is no reply by Koutsoyiannis.
Also, Eli can't find it being discussed most anywhere at all and certainly not at Curry's. The editors at Proc. T. Soc. A seem to have tossed Koutsoyiannis under the bus.