Assessing the habitability of planets with Earth-like atmospheres with 1D and 3D climate modeling

TL;DR

This study evaluates the effectiveness of 1D climate models in estimating the habitability of Earth-like exoplanets by comparing their results with 3D models, highlighting their potential and limitations.

Contribution

It demonstrates that 1D climate models, with adjustable parameters, can approximate 3D model results for planetary habitability assessments.

Findings

1D models can replicate 3D climate surface temperatures under certain parameters.

Habitability conclusions are consistent between 1D and 3D models when using similar parameters.

Large climate variability exists for Earth-like planets depending on surface albedo and humidity.

Abstract

The habitable zone (HZ) describes the range of orbital distances around a star where the existence of liquid water on the surface of an Earth-like planet is in principle possible. While 3D climate studies can calculate the water vapor, ice albedo, and cloud feedback self-consistently and therefore allow for a deeper understanding and the identification of relevant climate processes, 1D model studies rely on fewer model assumptions and can be more easily applied to the large parameter space possible for exoplanets. We evaluate the applicability of 1D climate models to estimate the potential habitability of Earth-like exoplanets by comparing our 1D model results to those of 3D climate studies in the literature. We applied a cloud-free 1D radiative-convective climate model to calculate the climate of Earth-like planets around different types of main-sequence stars with varying surface albedo and relative humidity profile. These parameters depend on climate feedbacks that are not treated self-consistently in most 1D models. We compared the results to those of 3D model calculations in the literature and investigated to what extent the 1D model can approximate the surface temperatures calculated by the 3D models. The 1D parameter study results in a large range of climates possible for an Earth-sized planet with an Earth-like atmosphere and water reservoir at a certain stellar insolation. At some stellar insolations the full spectrum of climate states could be realized, i.e., uninhabitable conditions as well as habitable surface conditions, depending only on the relative humidity and surface albedo assumed. When treating the surface albedo and the relative humidity profile as parameters in 1D model studies and using the habitability constraints found by recent 3D modeling studies, the same conclusions about the potential habitability of a planet can be drawn as from 3D model calculations.