There was no life back then. with 4k CO2, not to mention higher methane, the temps would have been roughly 20 degrees higher than today. People fry at a +4 increase. Clearly the idea that there was an ice age back then has been greatly exaggerated.
/sarc_off
“CO2 needs to get very low to have an ice age (i.e. 200 ppm) – which is why the Ordovician had an ice age at 4,000 ppm.”
That was when our sun was only lukewarm. Astrophysicists say so.
There was no life back then. with 4k CO2, not to mention higher methane, the temps would have been roughly 20 degrees higher than today. People fry at a +4 increase. Clearly the idea that there was an ice age back then has been greatly exaggerated.
/sarc_off