A critical component of a habitable planet is its ability to stabilize its climate over long timescales. In a new study, scientists explore whether a world covered in water can keep its climate as stable as an Earth-like, continental world.
The Carbon Goes Round and Round
Diagram of the physical and chemical processes (top panel) and feedback loops (bottom panel) associated with the carbonate–silicate cycle. Click to enlarge. [Gretashum]Over the span of millions of years, a planet’s host star might gradually dim or brighten, or the planet’s volcanic outgassing patterns might slowly shift. If evolution like this also caused dramatic changes in the overall climate of a planet, this would spell bad news for habitability: the planet might not be able to retain liquid water over timescales long enough for life to form and evolve.
So how do you keep a climate stable against these slow shifts? One crucial factor is having a carbonate–silicate cycle. This cycle dictates how carbon is moved around a planet, sometimes burying it deep below the planet’s surface, sometimes releasing it out into the atmosphere.
On Earth, a simplified description of the carbonate–silicate cycle is:
Atmospheric carbon dioxide dissolves in rainwater, forming carbonic acid, which ...