CO2 – Visualized Temperature Contribution

CSS-21 In this Climate Short Story (CSS), I am attempting to provide visualizations of the CO₂ contribution to warming/cooling over a variety of time scales. When you apply basic atmospheric CO₂ science, the CO₂ contribution to warming is generally a small percentage of the overall temperature change. My starting point is the satellite measurement of energy radiating to space. The “GreenHouse Gas (GHG)” effect is represented by the difference in the Planck Curve (no atmospheric GHG) and the Schwartzchild Curve. At CO₂ levels of 400 ppm, the impact of CO₂ is very visible on the Schwartzchild Curve. But a significant portion of that contribution occurred at much lower CO₂ levels and a doubling of CO₂ to the 800 ppm level will not add much to the “GHG” effect. The relatively narrow CO₂ Absorption Band is becoming saturated as laid out by W. A. van Wijngaarden and W. Happer in their 2021 paper “Relative Potency of Greenhouse Molecules”. This CSS takes three scenarios and applies those CO₂ Climate Sensitivities to the Temperature changes over a variety of historical time scales. The first scenario comes out of the Schwartzchild Curves at various CO₂ levels (produced using the University of Chicago’s MODTRAN models). The incremental temperature associated with CO₂ increases can be backed out and a CO₂ Climate Sensitivity (varying with CO₂ concentrations) can be put together.

#climatechange #delaythegreen #globalwarming #showusthedata

The other two scenarios are based on constant CO₂ climate sensitivities. There are two measurements of CO₂ Climate Sensitivity. The first parameter is the Transient Climate Response (TCR). The TCR represents the global temperature response that can be expected (over roughly 70 years) by a doubling of CO₂. The second parameter is the Equilibrium Climate Sensitivity (ECS). The ECS is the global temperature response that can be expected over a much longer time, that allows the climate system to come to equilibrium. The CO₂ Climate Sensitivity is no where near to being settled science. Even the IPCC uses a wide “unsettled” ECS range of 1.8 to 5.6 °C/CO₂ doubling. Those higher ECS values use unsubstantiated positive water vapour feedback to arbitrarily multiply CO₂’s warming capabilities. Given that the low value of ECS (1.8 °C) is the only value that somewhat accurately reflects the measured Lower Tropospheric temperatures, you would expect that would be the ECS value that they would use. But no, they prefer to keep those higher ECS values in play. After all, they fit better with the narrative. Strange scientific choice, given that they also admit that their models run too hot (my OPS-55 – The State of Climate Science post provides some more detail).

Climate Sensitivity estimates (ECS and TCR) have been trending down for the last 15 years as shown on CSS-20e. How low will they go? That remains to be seen, but the work laid out by van Wijngaarden and Happer give us a pretty good indication. I will use an ECS of 1.8 °C and a TCR of 1.2 °C. The ECS estimates are already below 2.0 °C. So, a ECS value of 1.8 °C is not a stretch and corresponds to the only IPCC model that gets close to modelling the observed Lower Tropospheric temperatures. The IPCC’s TCR estimate (prior to applying their positive feedback fudge factors) is roughly 1.2 °C. This is very likely high since many researchers put the TCR at somewhere less than 1.0 °C. Factoring in the Urban Heat Island Effect (UHIE) could easily take that TCR down to the 0.75 °C range.

Regardless of the time scale, CO₂ cannot have a major impact on the temperature change over CO₂ concentrations that we or our descendants will realistically encounter. This analysis confirms my practice of plotting CO₂ on vertical scales that reflect CO₂’s contribution to the warming since the 1850s (135 ppm ≡ 1.07 °C, IPCC estimates). That “large” increase in CO₂ is not that large (or scary) when shown in proper context or in relation to historical global CO₂ concentrations. A quick look at vertical scale implications is laid out in my OPS-54 – CO₂-Temperature – Properly Scaled post. In this CSS, I have plotted both the CAGW alarmist scary version and a version of CO₂ concentration that reflects the Climate Sensitivity. This is a technical discussion, but the impact of CO₂ on temperature is very simply represented by looking at the small red shading (representing the theoretical component of CO₂ warming) and the green shading (all the other natural forcings that are acting on our planet). CO₂ is a minor player at best and will just continue to get less effective as CO₂ levels rise. The last slide introduces an alternative analysis using the MODTRAN Model. The analysis produces a curve that  lies between the MODTRAN representation shown in the Temperature plots and the IPCC TCR representation. My first inclination is that this may be the most representative option. I am not going to make any changes to my evaluation until I have thought some more on the subject and have a chance to review any feedback.