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Post by David B. Benson on May 22, 2022 6:12:09 GMT 9.5
A thread to drop links to various papers about climatology which may prove useful to reference in future discussions. The first of these is Why The Radiative Forcing of CO2 is a Logarithmic Function of Atmospheric CO2 Concentrations Nick Lutsko 2018 Aug 26 nicklutsko.github.io/blog/2018/08/26/Why-CO2-Forcing-Is-Logarithmicso one doesn’t have to start from On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground Svente Arrhenius 1896 April Philosophical Magazine and Journal of Science www.rsc.org/images/Arrhenius1896_tcm18-173546.pdfThen one simply measures the forcing due to all atmospheric so-called greenhouse trace gases: Correlation between CO2 climate forcing and temperature Grant Foster aka Tamino 2022 May 05 Open Mind tamino.wordpress.com/2022/05/05/correlation-between-co2-climate-forcing-and-temperature/and then noting, as in the comments, that CO2 is about 0.83 of the total forcing, resulting in the actual TCR, ‘actual’ transient climate response, due to CO2 is close to 2.0 K. Then the CO2-only ECS, equilibrium climate sensitivity, is close to 3.3 K. However, with the rest of the current crop of global warming trace gases, ECS is more like 4 K. (See the comments section for the source of these latter remarks.) Note that the usual definition of TCR requires an increase of 1% per annum in atmospheric CO2. Hence using the observed increase provides an ‘actual’ TCR. Also note that the logarithm is to the base 2.
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Post by Russell Seitz on May 22, 2022 7:48:57 GMT 9.5
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Post by David B. Benson on May 23, 2022 12:17:51 GMT 9.5
The atmospheric CO2 record is extended into the past to before the beginning of the modern measurements, the Keeling curve, by the use of the high quality data from Law Dome, Antarctica. This is possible due to the exceptional snowfall rate at this site. The most recent analysis of the data is Revised records of atmospheric trace gases CO2, CH4, N2O and delta 13 C-CO over the last 2000 years from Law Dome Antarctica M. Rubino et al. 2019 Apr 11 Earth Sys. Sci. Data 11, 473–472, 2019 essd.copernicus.org/articles/11/473/2019/essd-11-473-2019.pdf
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Post by David B. Benson on May 24, 2022 13:20:19 GMT 9.5
The artificial production of carbon dioxide and its influence on temperature G. S. Callendar 1938 Feb 16 Quarterly Journal of thr Royal Meteorological Society www.rmets.org/sites/default/files/qjcallender38.pdfSee figure 2 for a graph highly similar to the current usage of log(c/c0).
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Post by David B. Benson on May 25, 2022 2:18:14 GMT 9.5
The approximation of the surface temperature forcing due to atmospheric CO2 is, according to IPCC 1990 on page 100/414 on my browser, taken from Relative contributions of different trace gases to the greenhouse effect T M L Wigley Climate Monitor v. 16, 1987, pp 14–28 for the functional form F = S*log(c/c0) where S is the climate sensitivity to atmospheric carbon dioxide, c is the current concentration and c0 is the base concentration, typically taken as 280 ppm for the period 1750–1800 CE. It is the sensitivity S which Grant Foster aka Tamino has determined in the OpenMind post cited supra. Unfortunately, I have no way of linking to the Wigley paper, so calling this functional form the Wigley approximation remains provisional. Two derivations of this functional form are found in Derivation of IPCC expression DeltaF=5.35ln(C/C0) www.globalwarmingequation.info/eqn%20derivation.pdfEdited to add: The Wikipedia page en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_effectnow contains a quote from the paper from Arrhenius which, in effect, gives the logarithmic form, but directly for the temperature, not for the forcing, calling it a ‘rule’. That is a suitable term as this is an approximation to the atmospheric physics acting over the entire globe, so not a ‘law’. So I will henceforth call Δt = τ*lg(c/c0) the Arrhenius-Wigley rule, as I think that Tom Wigley deserves some credit for this as well. In the now-named Arrhenius-Wigley rule, Δt is the increment of temperature attributed to atmospheric carbon dioxide, the other long-lived trace heat-trapping gases just coming along for the ride, i.e., ignored, τ is the aTCR, actual transient climate response as determined by the slope of the correlation, as by Grant Foster, c is the current atmospheric carbon dioxide concentration in ppm and c0 is the base concentration, typically taken to be 280 ppm for the pre-industrial times. In addition, note that the logarithm is lg=log_2, the logarithm to base 2 so that a doubling of CO2 gives the increase in temperature of exactly the aTCR.
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Post by David B. Benson on May 26, 2022 6:37:32 GMT 9.5
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Post by David B. Benson on Oct 13, 2023 3:09:01 GMT 9.5
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Post by David B. Benson on Oct 14, 2023 3:57:36 GMT 9.5
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