Radiative forcing of carbon dioxide and the stratospheric cooling
- Antero Ollila
- Aug 22
- 3 min read
This is my proposal for the report of U.S. Department of Energy by the name "A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate"
Addition to 5.5
CO2 is the most important climate driver according to AR6, having the RF value of 2.16 Wm-2, corresponding to 80 % of the total Radiative Forcing (RF) of 2.70 Wm-2 (Figure 7.6). The RF value of CO2 concentration of 560 ppm (applicable in CS calculations) in AR6 is 3.93 Wm-2. This value includes the rapid adjustment of the stratospheric cooling (SC). The formation of the numerical value of SC has been represented unclearly in the AR6. The effective radiative forcing (ERF) is the total forcing, being the sum of instantaneous radiative forcing (IRF) at the TOA and the rapid adjustments (Smith et al., 2018). It should be noted that the AR6 applies the SC definitions and values of Smith et al. (2018), which are different from the AR5 definitions.
It turns out that the sum of other adjustments is zero except SC, which has the value of about 1.1 Wm-2 both in Figure 7.4 of the AR6 (30 % of the SARF value of 3.7 Wm-2) and in Figure 3 of Smith et al., 2018. The IRF value according to these calculations is only about 2.8 Wm-2. It means that the stratospheric cooling increases the total RF value (=ERF) of CO2 by 30 %. This simple fact has been obscured in the AR6, since the numerical value of IRF has not been shown in the AR6.
This may be a surprise even to most climate scientists that according to the IPCC, the CO2 warms up the troposphere with the RF effect of 2.8 Wm-2, and in the stratosphere, the CO2 has a cooling effect with the RF impact of 1.1 Wm-2. In some research studies about this stratospheric cooling phenomenon, the term ”stratospheric temperature adjustment” is used instead of SC, but the natural forces cannot adjust temperature profiles since they react only to energy imbalances.
There are three research studies of contrarian scientists, who have applied the LBL method for ERF value calculations for 560 ppm of CO2, and their results are rather close to the IRF value of 2.8 Wm-2: Harde (2013) 2.4 Wm-2, Miskolczi and Mlynzack (2004) 2.53 Wm-2, and Ollila (2023) 2.65 Wm-2. There might be doubts about the capability of these researchers to apply the LBL method, but, for example, Ollila (2017) has calculated the total RF value of CO2 to be 20.1 Wm-2 in the present atmosphere, which is very close to the value of 21.7 Wm-2 by Schmidt et al. (2010).
Summa summarum, this means that there are justified doubts about the RF value of CO2.
References
Harde, H. (2013.) Radiation and heat transfer in the atmosphere: A comprehensive approach on a molecular basis. International Journal of Atmospheric Sciences, ID 503727. https://doi.org/10.1155/2013/503727
Miskolczi, F.M., and Mlynczak, M.G. (2004). The greenhouse effect and the spectral decomposition of the clear-sky terrestrial radiation. Idöjaras 108: 209-251. https://klimaszkeptikusok.hu/wp-content/uploads/2017/03/10_IDJS_Vol108_No4_2004-1.pdf
Ollila, A. (2017). Warming effect reanalysis of greenhouse gases and clouds. Physical Science of International Journal 13(2):1-13. http://www.journalrepository.org/media/journals/PSIJ_33/2017/Jan/Ollila1322016PSIJ30781_1.pdf
Ollila, A. (2023). Radiative forcing of climate sensitivity of carbon dioxide (CO2) fine-tuned with CERES data, Current Journal of Applied Science and Technology 42(46), 111–133.
Schmidt, G.A., Ruedy, R.A., and Miller, R.L. (2010). Attribution of the present-day total greenhouse effect. Journal of Geophysical Research 115:D20106. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2010JD014287
Smith, CJ., Kramer, R.J., Myhre, G. et al. (2018).Understanding rapid adjustments to diverse forcing agents. Geophysical Research Letters 45:2023–12031. https://pmc.ncbi.nlm.nih.gov/articles/PMC6334512/
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