Waterworlds May Have Better Climate Buffering Capacities than Their Continental Counterparts

The long-term habitability of a planet is often assumed to be controlled by its ability to cycle carbon between the solid planetary interior and atmosphere. This process allows the planet to respond to external forcings (i.e., changes in insolation, changes in volcanic outgassing rates, etc.) and regulate its surface temperature through negative feedbacks on atmospheric CO2 involved in silicate weathering. Continental weathering and seafloor weathering rates have different, non-linear dependencies on pCO2 and will respond differently to changes in external forcings. Because waterworlds (planets with only seafloor weathering) have a weaker pCO2 dependence than continental worlds (such as modern Earth), we find that waterworlds are better at resisting changes in surface temperature resulting from perturbations in insolation than their continental counterparts, and may be more habitable in this respect.