Climate bistability of Earth-like exoplanets

TL;DR

This study investigates the conditions under which Earth-like exoplanets can exhibit climate bistability, revealing that such conditions are similar to those supporting complex life, using an efficient climate modeling approach.

Contribution

The paper introduces an application of the Earth-like planet surface temperature model (ESTM) to identify climate bistability in exoplanets and explores its dependence on planetary parameters.

Findings

Climate bistability occurs within specific parameter ranges.

Conditions for bistability are similar to those supporting complex life.

ESTM effectively reproduces Earth's climate bistability.

Abstract

Before about 500 million years ago, most probably our planet experienced temporary snowball conditions, with continental and sea ices covering a large fraction of its surface. This points to a potential bistability of Earth's climate, that can have at least two different (statistical) equilibrium states for the same external forcing (i.e., solar radiation). Here we explore the probability of finding bistable climates in earth-like exoplanets, and consider the properties of planetary climates obtained by varying the semi-major orbital axis (thus, received stellar radiation), eccentricity and obliquity, and atmospheric pressure. To this goal, we use the Earth-like planet surface temperature model (ESTM), an extension of 1D Energy Balance Models developed to provide a numerically efficient climate estimator for parameter sensitivity studies and long climatic simulations. After verifying that the ESTM is able to reproduce Earth climate bistability, we identify the range of parameter space where climate bistability is detected. An intriguing result of the present work is that the planetary conditions that support climate bistability are remarkably similar to those required for the sustainance of complex, multicellular life on the planetary surface. The interpretation of this result deserves further investigation, given its relevance for the potential distribution of life in exoplanetary systems.