Responding to the CO2 Coalition's "Facts #6 and #7" on CO2 Concentrations on Geologic Time Scales
CO2 Coalition 's " fact #6 " and " fact #7 " are essentially identical, and both are largely just a rehash of statements made in previous "facts." Here we're told that "our current geologic period, the Quaternary, has seen the lowest average levels of carbon dioxide since the Precambrian." To support this claim, they took the data from the climate model in Berner 2001 and averaged all the CO2 concentration values for each Geologic period, ignoring the confidence intervals and the length of the period, and plotted the following graph. Note that each geologic period is shown as if they were the same length. As I've already shared , CO2 proxies often paints a somewhat different picture from Berner 2001's climate model. The model has been updated several times since 2001, but the CO2 Coalition appears to be completely unaware of this. Here again is the proxy evidence we have for CO2. It's pretty sparse before the proliferation of