Phosphorus and Life on a Water World

Abstract

On Earth, the major mechanism for providing the vital limiting nutrient phosphorus necessary to fuel biological productivity and the long arc of evolution is weathering of exposed continental rocks. It has been presumed that life may not be present on exoplanets with substantially more water than Earth. Many of these “Water Worlds” exist, but without exposed land mass for weathering, there is not a viable mechanism for nutrient delivery and climate stabilization. In novel laboratory experiments performed in chambers designed to mimic the weathering of seafloor basalts in anoxic conditions, Syverson et al. (2021, https://doi.org/10.1029/2021GL094442) found that silicate weathering in these conditions release an adequate amount of phosphorus to fuel a robust biosphere, at least in an idealized system. Perhaps we shouldn't rule out “Water Worlds” as potential harbors for life after all?