Aquaplanet

Aquaplanet is a term used in planetary science and climate science to describe a planet whose surface is dominated by liquid water, typically an ocean world with little or no exposed land. In exoplanet studies, aquaplanets are often invoked as hypothetical, water-rich planets for exploring climate and habitability.

In climate modeling, an aquaplanet configuration refers to a simplified general circulation model setup where the planetary surface is a globally uniform ocean layer, sometimes of fixed depth, with no continents or topographic relief. This boundary condition removes land-sea contrasts and simplifies albedo and heat transport, allowing researchers to study fundamental atmospheric dynamics, energy balance, and climate sensitivity.

Variants include different ocean depths, mixed-layer models, or fully coupled ocean dynamics, as well as different insolation patterns and planetary rotation rates. The resulting climate regimes emphasize basic features such as the Hadley circulation, planetary waves, and the response of the hydrological cycle to warming, with cloud feedbacks remaining a key uncertainty.

In the context of exoplanets, aquaplanets are used to probe how global oceans influence climate stability and potential habitability under varying stellar flux and rotation. They serve as a benchmark against more complex, Earth-like worlds with landmasses.

Limitations of aquaplanet models include the lack of continents, ice dynamics, and realistic albedo variations; while useful for isolating processes, they cannot capture many phenomena driven by land-sea contrasts. Related concepts are waterworlds and ocean planets.