Constraint II · Pressure
There is not enoughcarbon dioxide.There never was.
§05Constraint II · Pressure
The Jakosky ceiling
All accessible CO₂ (polar caps ~4–12 mbar, adsorbed regolith, exposed carbonates) totals ≈ 3× the present atmosphere, or ~18–20 mbar. Holding 1 bar as carbonate would need a global carbonate layer ~15 m thick, which is not observed.
The Armstrong limit
20 mbar does not reach 62.7 mbar, below which body-temperature water boils. Pressure suits remain mandatory. Endogenous CO₂ cannot even release humans from a suit.
Total accessible CO₂ (Jakosky 2018)
~20 mbar
Armstrong limit, body-temperature water
62.7 mbar
Global carbonate layer thickness required for 1 bar
~15 m
Because carbon disposal is a 3.5-million-year problem, a thick CO₂ atmosphere is not merely blocked by inventory. It is the wrong objective. A liability you pay to create and pay again to destroy.