[galangalalgol]

The way I read it, it isn't a co2 greenhouse, in fact the death stroke is the increased co2 absorption at those temperatures due to weathering of rock. Driving co2 below what plants can survive. Building a parasol at l1 that can be modulated to vary what is passed and what is harvested will be necessary at some point. It could get a couple extra billion years potentially.

[pfdietz]

That destroys higher life, but tough microorganisms survive until the runaway steam greenhouse sterilizes the planet.