Climate uncertainties caused by unknown land distribution on habitable M-Earths

Abstract

A planet's surface conditions can significantly impact its climate and habitability. In this study, we use the 3D general circulation model ExoPlaSim to systematically vary dayside land cover on a synchronously rotating, temperate rocky planet under two extreme and opposite continent configurations, in which either all of the land or all of the ocean is centred at the substellar point. We identify water vapour and sea ice as competing drivers of climate, and we isolate land-dependent regimes under which one or the other dominates. We find that the amount and configuration of land can change the planet's globally averaged surface temperature by up to 20K, and its atmospheric water vapour content by several orders of magnitude. The most discrepant models have partial dayside land cover with opposite continent configurations. Since transit spectroscopy may permit observations of M-dwarf planets' atmospheres, but not their surfaces, these land-related climate differences likely represent a limiting uncertainty in a given planet's climate, even if its atmospheric composition is known. Our results are robust to variations in atmospheric CO2 concentration, stellar temperature, and instellation.

13 pages, 10 figures

References in corpus (20)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• The habitability of Proxima Centauri b II. Possible climates and Observability
• Atmospheric dynamics of Earth-like tidally locked aquaplanets
• Atmospheric characterization of Proxima b by coupling the Sphere high-contrast imager to the Espresso spectrograph
• Impact of Clouds and Hazes on the Simulated JWST Transmission Spectra of Habitable Zone Planets in the TRAPPIST-1 System
• The rotational and divergent components of atmospheric circulation on tidally locked planets
• Deciphering thermal phase curves of dry, tidally locked terrestrial planets
• The atmospheric circulation and climate of terrestrial planets orbiting Sun-like and M-dwarf stars over a broad range of planetary parameters
• Water Trapping on Tidally Locked Terrestrial Planets Requires Special Conditions
• Simulations of Water Vapor and Clouds on Rapidly Rotating and Tidally Locked Planets: a 3D Model Intercomparison
• Thermodynamic and Energetic Limits on Continental Silicate Weathering Strongly Impact the Climate and Habitability of Wet, Rocky Worlds
• No Snowball on Habitable Tidally Locked Planets with a Dynamic Ocean
• The Effect of Substellar Continent Size on Ocean Dynamics of Proxima Centauri b
• Mineral dust increases the habitability of terrestrial planets but confounds biomarker detection
• ExoPlaSim: Extending the Planet Simulator for Exoplanets
• The Effect of Land Albedo on the Climate of Land-Dominated Planets in the TRAPPIST-1 System
• Stabilization of dayside surface liquid water via tropopause cold trapping on arid slowly rotating tidally locked planets
• The Effect of Land Fraction and Host Star Spectral Energy Distribution on the Planetary Albedo of Terrestrial Worlds
• Multiple moist climate equilibrium states on arid rocky M-dwarf planets: A last-saturation tracer analysis