by Natura Naturans
In yet another new paper (Drotos et al., 2020), scientists determine the climate sensitivity to CO2 is “practically zero” the more the concentration rises. A ~4450 ppm CO2 concentration has cooler climates than observed in the pre-industrial (278 ppm) era. Why? A self-amplifying cloud feedback mechanism cools the Earth by magnitudes “as large as 10 K” upon warming saturation.
Earlier this year, scientists published a paper using mesocosms (controlled outdoor experiments) to demonstrate CO2 concentrations of 3200, 7500, and 16,900 ppm are associated with colder temperatures than in outdoor environments with 480 ppm CO2 concentrations.
Now, in another new paper (Drotos et al., 2020), several more scientists are asserting the Earth system has an internal, self-amplifying negative cloud feedback mechanism so powerful that:
“at CO2 concentrations beyond four times the preindustrial value, the climate sensitivity decreases to nearly zero as a result of episodic global cooling events as large as 10 K”.
Empirical Evidence Shows Temperature Increases Before CO2 Increase in ALL Records
Guest Blogger / September 9, 2018
Guest Opinion: Dr. Tim Ball
In 1999 the first significant long term Antarctic ice core record appeared. Earlier cores were in the record, but as I recall, the one by Petit, Raynaud, and Lorius were presented as the best representation of temperature, CO2, and deuterium over 420,000-year core drilled to 3623 meters. I recall Lorius warning people not to rush to judgment. One of his concerns was the size of the graph depicting such a long record. Lorius reconfirmed this position in a 2007 article.
“…our [East Antarctica, Dome C] ice core shows no indication that greenhouse gases have played a key role in such a coupling [with radiative forcing]”
In the original article, as Euan Mearns notes in his robust assessment, the authors believed that temperature increase preceded CO2 increase.
In their seminal paper on the Vostok Ice Core, Petit et al (1999)  note that CO2 lags temperature during the onset of glaciations by several thousand years but offer no explanation. They also observe that CH4 and CO2 are not perfectly aligned with each other but offer no explanation. The significance of these observations are (sic) therefore ignored. At the onset of glaciations temperature drops to glacial values before CO2 begins to fall suggesting that CO2 has little influence on temperature modulation at these times.
The bottom line is that rising temperatures cause carbon levels to rise. Carbon may still influence temperatures, but these ice cores are neutral on that. If both factors caused each other to rise significantly, positive feedback would become exponential. We’d see a runaway greenhouse effect. It hasn’t happened. Some other factor is more important than carbon dioxide, or carbon’s role is minor.
The 800 year lag in CO2 after temperature – graphed
Carbon dioxide follows temperature in the Vostok Ice Cores
In the 1990′s the classic Vostok ice core graph showed temperature and carbon in lock step moving at the same time. It made sense to worry that carbon dioxide did influence temperature. But by 2003 new data came in and it was clear that carbon lagged behind temperature. The link was back to front. Temperatures appear to control carbon, and while it’s possible that carbon also influences temperature these ice cores don’t show much evidence of that. After temperatures rise, on average it takes 800 years before carbon starts to move. The extraordinary thing is that the lag is well accepted by climatologists, yet virtually unknown outside these circles. The fact that temperature leads is not controversial.