Snowball Earth vs Hot House Earth

In reminding ourselves about the causal relationship between warming and the greenhouse effect, let us remind ourselves that during the hundreds of millions of years after the Earth first formed, temperatures were higher then than they are now despite the sun’s output being considerably less than it is now. Anaerobic life evolved and flourished in conditions with high methane and CO2 levels for many Eons. Then Cyanobacteria came into being and released oxygen thru photosynthesis. This caused a great dying off of the anaerobics and interacted with the methane and broke it down into CO2 and H2O. The weathering of basaltic surfaces eliminated a lot of the free carbon dioxide and the CO2 levels got so low that the Earth became what scientists call Snowball Earth. Eventually, however, the CO2 and oxygen levels balanced out and new life forms evolved and flourished in the pre-Cambrian Period. After this, the only times that great extinctions occurred were when CO2 levels soared due to natural catastrophes.

When Too Much (Hothouse Earth) or Too Little (Snowball Earth) Of A Good Thing (CO2) Is Not Good:

https://samslair.blogspot.com/2020/12/agw-when-too-much-or-too-little-of-good.html?m=1