The mean global temperature in the carboniferous period, with CO2 concentrations over double of present day was an astounding, just wait for it... 14C, which is the incredible, * unbelievable* 0C above the mean present day global temperature.
As CO2 levels spiked in the carboniferous period, it is marked by the drop of sea levels by 120m to the present day level, and as the CO2 level subsided, the sea levels rose 80m.
Sorry, but "off the scale" only counts when you actively pick and choose what scale you want to use, which in terms of geological temperature, CO2 and O2 concentrations quite literally means disregarding millions of years of geological time.
