Mass of CO₂ in the surface, mantle and core reservoirs after 100 Myr of evolution for Earth (filled circles) and Mars (asterisks) as a function of the partition coefficient of carbon between metal melt and silicate melt. The measurement is given for C + O₂ to reflect the CO₂ equivalent mass of the dissolved C in the core and the mantle. We mark the accreted CO₂ for Earth and Mars as well as the modern CO₂ reservoir in Venus' atmosphere. Lowering the partition coefficient leads to a decreased carbon storage in the core and more outgassing to the surface. The mantle holds negligible carbon in all cases. The escape of the reduced martian atmosphere removes any outgassed CO or CO₂ reservoirs from Mars. The symbols are displaced slightly horizontally to better distinguish them.