Characteristic evolutions of the atmospheric temperature and pressure and CO₂ flux in and out of the atmosphere for an Earth-mass planet at 1 au with an Earth-like (a–c) or a Mercury-like (d–f) interior structure. The colored background marks the state of water at the planet's surface. Both planets start with the same mantle water content of 250 ppm and an oxygen fugacity of 0.05 log₁₀ units above the IW buffer. Panels (a–c) and (d–f) correspond respectively to the points 1 and 2 marked in Figs. 3 and 4.