Habitable Climates
arXiv:0711.4856 · doi:10.1086/588089
Abstract
According to the standard liquid-water definition, the Earth is only partially habitable. We reconsider planetary habitability in the framework of energy-balance models, the simplest seasonal models in physical climatology, to assess the spatial and temporal habitability of Earth-like planets. We quantify the degree of climatic habitability of our models with several metrics of fractional habitability. Previous evaluations of habitable zones may have omitted important climatic conditions by focusing on close Solar System analogies. For example, we find that model pseudo-Earths with different rotation rates or different land-ocean fractions have fractional habitabilities that differ significantly from that of the Earth itself. Furthermore, the stability of a planet's climate against albedo-feedback snowball events strongly impacts its habitability. Therefore, issues of climate dynamics may be central in assessing the habitability of discovered terrestrial exoplanets, especially if astronomical forcing conditions are different from the moderate Solar System cases.
Accepted by ApJ. Several references added. 41 pages, 11 figures, 2 tables
References in corpus (5)
- Habitable planets around the star Gl 581?
- Vegetation's Red Edge: A Possible Spectroscopic Biosignature of Extraterrestrial Plants
- Detailed Models of super-Earths: How well can we infer bulk properties?
- Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres
- Characterizing the Orbital Eccentricities of Transiting Extrasolar Planets with Photometric Observations