Cenozoic – CO2-Temperatures

OPS-59 This post is a little add-on to my CSS-10 – A Ride Through the Cenozoic post. When I put the CSS-10 post together, I had not converted the carbon isotope ratios (δC₁₃ ≡ C₁₃/C₁₂) into an atmospheric CO₂ concentration. I used the Komar-Zeebe Cenozoic CO₂ estimates for the general correlations. This One Page Summary shows a representation of the Westerhold et al CO₂ concentrations. Pre-Oligocene, the δC₁₃ is inversed to account for different C₁₃ uptakes by the C3 plants that dominate at warmer temperatures. No inversion is required for the C4 plants that dominated after the colder weather set in. With the inversion in place, a representative CO₂ profile can be produced based on the proportionally adjusted carbon isotope ratios. As shown, the Eocene CO₂ highs were around 2,000 ppm, the Pleistocene CO₂ lows are around 200 ppm. The CAGW alarmist community likes to argue that the temperature change over the Cenozoic is due to CO₂. Just barely true despite some general correlation between CO₂ and Global Temperatures.

#climatechange #delaythegreen #globalwarming #showusthedata

Most of the temperature decline over the Cenozoic is due to some very significant plate tectonic and ocean cycle changes and a generally steady decline in Cosmic Ray Flux (CRF). A couple significant celestial impacts also played a role. The general atmospheric CO₂ concentration declines likely contribute a bit to the temperature declines, but most of the CO₂ decline is driven by the general temperature decline and natural CO₂ sequestration. There is a very simple reason that CO₂ cannot be responsible for much of the 16 °C+ temperature drop over the Cenozoic. Using the IPCC’s CO₂ Transient Climate Response (TCR, 1.2 °C), the CO₂ temperature contribution to the drop in CO₂ levels from 2,000 ppm to 500 ppm is only 2.4 °C. Using the Equilibrium Climate Sensitivity (ECS, 1.8 °C) the CO2 temperature response would be in the 3.6 °C range. On these longer time scales, the ECS is probably more representative. To be fair, I did plot the IPCC projections for both CO₂ and Temperature. Based on the RCP6.0 emission case, the high end of the IPCC expected temperature rise is 3.1 °C by 2100 (based on a roughly 500 ppm CO₂ increase to roughly 800 ppm). As shown, neither the rise in temperature nor the rise in CO₂ takes us to dangerous levels. Not scary and not surprising given that life thrived at the much higher temperatures and CO₂ levels that were present during the Eocene Climate Optimum. Assuming the IPCC “science” is correct, we will not even get back to the still cold temperatures of the Pliocene (5.3 to 2.6 million years ago). So, is the IPCC “science” correct? Questionable given the self admission that their models run too hot (back-up in my OPS-55 – The State of Climate Science post) and their programmed CO₂ ECS ranges from 1.8 °C to 5.6 °C (not really that settled as shown in my CSS-6 – John Christy – January 2021 post). The IPCC CO₂ TCR and ECS are exaggerated in the computer models by a factor of up to three using unsubstantiated water vapor feedbacks. Could that be one of the reasons that most of their models run too hot? I would say yes. They could actually solve most of their accuracy problems by dumping all of the high ECS models and going with the low sensitivity Russian model. They could also move off their simplistic, unscientific CO₂ centric viewpoint and include the many solar forcings they knowingly choose to ignore. The result will be a 2100 Temperature rise much lower than that shown in the plots here. I will show some more realistic temperature responses in an upcoming post.