Existence of liquid water on the planetary surface is thought to be an important condition for the origin and evolution of life. Planets with oceans (or lakes) are classified in two types: Earth-like ‘aqua planets’ and less water ‘land planets’. The latter shows stronger resistance than the former to the runaway greenhouse caused by the increase of stellar luminosity. We examined the possibility of evolution from an aqua planet to a land planet by water loss. We showed that an aqua planet with less than about 0.1 present Earth's ocean mass can evolve to a land planet without having experience of the runaway greenhouse, and maintains liquid water on its surface for about 2Gyrs longer than planets with larger amount of water. Our results mean that the initial amount of water is important for their evolution paths and habitability.

Planets with very little amount of water on their surface, called “land planets”, have wider habitable zones than that of Earth-like “aqua planets” (Abe et al. 2011). We investigated complete evaporation of surface liquid water for land planets using 1D energy balance model (EBM). We found that complete evaporation occurs when the planetary flux at the dry edge, which is defined as the boundary between the dry zone and the wet zone, exceeds the critical radiation flux of water saturated atmosphere. We define “complete evaporation limit” as the minimum insolation for complete evaporation that a planet receives. This limit depends on latitude of the dry edge, efficiency of meridional heat transport, and atmospheric character that modify the value of the critical flux.