Can the IPCC Computers Model the Holocene?

July 16, 2023 rjdavison

OPS-73 – Can the IPCC Computers Model the Holocene Download PDF

OPS-73 The answer is obviously NO! The models are currently programmed to reflect the Catastrophic Anthropogenic Global Warming (CAGW) alarmist “narrative” (i.e.: the warming since the pre-industrial era is due to human activity (primarily CO₂ emissions)). Both OPS-73 charts reflect that scaling. According to the IPCC AR6 report, temperatures have increased by 1.07 °C based on a 140 ppm CO₂ concentration increase. Note, the HadCRUT5 temperature curves have been compressed by 50% (a conservative estimate) to reflect the difference in data averaging between the MTR and the pre-MTR Holocene data. Assuming the CAGW alarmist “narrative” is correct (a massive and inaccurate assumption), the IPCC models simply cannot replicate the pre-MTR Holocene temperature fluctuations since CO₂ concentrations are virtually flat over that period.

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There are a few key points that run counter to the CAGW alarmist narrative.

As mentioned above, the temperatures fluctuate significantly throughout the pre-MTR Holocene. CO₂ (which is virtually flat) is not driving those fluctuations. Natural forcings (primarily solar, through direct and indirect means) are responsible for the fluctuations. Those natural forcings were still active during the MTR and they will continue to be active in the future.
Half of the temperature rise occurred pre-1950, while 86%+ of human emissions occurred post-1950. Those two facts do not fit the CAGW alarmist “narrative” very well.
A portion of the 1.07 °C rise is dependent on the “homogenization” (i.e.: data manipulation) process. How much manipulation is an open question.
The computer models “run way too hot”. That statement comes directly from the modelers. (CSS-30 – CMIP6 Climate Models and OPS-55 – The State of Climate Science).
The evaluations still use implausibly high emission scenarios (ssp3-7.0 and ssp5-8.5) which the IPCC has deemed low likelihood scenarios.
The natural forcings, when programmed into the models (and used) can more accurately model the MTR without CO₂ contribution. I showed that in a simple spreadsheet model (OPS-8 – Basic Climate Model and my Open Letter Addendum) a while back. The current CMIP6 protocol has several solar forcings built in (over and above the absolute TSI used in the CMIP5 protocol). In beta testing, those models also history matched the MTR without CO₂ contribution. More recently, Nicola Scafetta published a paper showing a better (more realistic) history match than CO₂. I expanded on his discussion in my CSS-42 – The Role of the Sun and CSS-43 – Modeling Over the Holocene posts.
All four temperature datasets show the Little Ice Age. Temperatures began increasing in Antarctica (Dome C) 405 years ago, adding ±1.4 °C prior to the MTR (1850 to the present). In the Arctic, temperatures began increasing around 350 years ago (with the Vinther et al Arctic Average adding ±0.7 °C and Greenland (GISP2) adding ±0.3 °C pre-MTR). Those warmings are not due to CO₂. And most of the warming from 1850 to 1950 has only minor CO₂ contribution levels (with little of that due to human emissions which were mostly post-1950 (86%+)). Plot attached.

You may see a facsimile of the OPS-73 MTR chart in the mainstream media, but you will not see the OPS-73 Holocene chart there (just not that scary). The CAGW alarmist plots are scaled to exaggerate the CO₂ change (i.e.: scaled for propaganda). The attached plots show the difference between a propagandized view and the closer to reality view. With proper modelling parameters, the CO₂ scale will be compressed even further to reflect the natural forcing contributions that are currently being ignored.

A Phanerozoic graph of Global Temperatures and CO₂ concentrations is also included to put our 1.07 °C and 140 ppm rises in perspective. Life flourished over the Phanerozoic outside of some celestial intrusions and deep ice ages (like the Pleistocene we are living through right now). So, no, “There is no Climate Emergency”.