Impacts of Atmospheric Carbon Species and Stellar Type on Climates of Terrestrial Planets

Fuente: arXiv
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Autores principales: Landry, Jared, Kurokawa, Hiroyuki, Taki, Tetsuo, Fujii, Yuka, Aoki, Kosuke, Genda, Hidenori
Formato: Preprint
Publicado: 2025
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author Landry, Jared
Kurokawa, Hiroyuki
Taki, Tetsuo
Fujii, Yuka
Aoki, Kosuke
Genda, Hidenori
author_facet Landry, Jared
Kurokawa, Hiroyuki
Taki, Tetsuo
Fujii, Yuka
Aoki, Kosuke
Genda, Hidenori
contents The climates of terrestrial planets are largely determined by the composition of their atmospheres and spectral types of their host stars. Previous studies suggest a wide range of carbon species abundances (CO\textsubscript{2}, CO, and CH\textsubscript{4}) can result from variations in reducing fluxes and stellar spectral types which influence photochemistry. However, a systematic investigation of how varying carbon species, particularly CO, affect planetary climates across wide parameter spaces remains limited. Here, we employ a one-dimensional radiative-convective equilibrium model to examine the dependence of planetary climate on the abundances of carbon species and host star type. We find that CO, due to weak absorption of stellar radiation, induces only moderate changes in stratospheric temperature, while its effect on surface temperature is negligible. Under Earth-like $p_\mathrm{N_2}$ (where $p_\mathrm{i}$ is the partial pressure on the surface of species i), for cases with fixed $p_\mathrm{CO_2}$, increase in CO leads to surface cooling on planets orbiting Sun-like stars unless the sum of $p_\mathrm{CO_2}$ and $p_\mathrm{CH_4}$ exceeds $\sim$1 bar. Whereas it results in surface warming for planets around M-type stars. When the total pressure of carbon species is fixed, converting CO\textsubscript{2} or CH\textsubscript{4} into CO always induces cooling. These effects arise from a combination of CO Rayleigh scattering, pressure broadening of greenhouse gas absorption lines, and \textcolor{red}{varying water vapor levels}. We further discuss how CO- and CH\textsubscript{4}-driven cooling (warming) can trigger positive (negative) climate-photochemistry feedback, influencing atmospheric evolution. Additionally, we suggest CO-rich planets may be less susceptible to water loss and atmospheric oxidation due to lower stratospheric water vapor content.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05975
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Impacts of Atmospheric Carbon Species and Stellar Type on Climates of Terrestrial Planets
Landry, Jared
Kurokawa, Hiroyuki
Taki, Tetsuo
Fujii, Yuka
Aoki, Kosuke
Genda, Hidenori
Earth and Planetary Astrophysics
Atmospheric and Oceanic Physics
The climates of terrestrial planets are largely determined by the composition of their atmospheres and spectral types of their host stars. Previous studies suggest a wide range of carbon species abundances (CO\textsubscript{2}, CO, and CH\textsubscript{4}) can result from variations in reducing fluxes and stellar spectral types which influence photochemistry. However, a systematic investigation of how varying carbon species, particularly CO, affect planetary climates across wide parameter spaces remains limited. Here, we employ a one-dimensional radiative-convective equilibrium model to examine the dependence of planetary climate on the abundances of carbon species and host star type. We find that CO, due to weak absorption of stellar radiation, induces only moderate changes in stratospheric temperature, while its effect on surface temperature is negligible. Under Earth-like $p_\mathrm{N_2}$ (where $p_\mathrm{i}$ is the partial pressure on the surface of species i), for cases with fixed $p_\mathrm{CO_2}$, increase in CO leads to surface cooling on planets orbiting Sun-like stars unless the sum of $p_\mathrm{CO_2}$ and $p_\mathrm{CH_4}$ exceeds $\sim$1 bar. Whereas it results in surface warming for planets around M-type stars. When the total pressure of carbon species is fixed, converting CO\textsubscript{2} or CH\textsubscript{4} into CO always induces cooling. These effects arise from a combination of CO Rayleigh scattering, pressure broadening of greenhouse gas absorption lines, and \textcolor{red}{varying water vapor levels}. We further discuss how CO- and CH\textsubscript{4}-driven cooling (warming) can trigger positive (negative) climate-photochemistry feedback, influencing atmospheric evolution. Additionally, we suggest CO-rich planets may be less susceptible to water loss and atmospheric oxidation due to lower stratospheric water vapor content.
title Impacts of Atmospheric Carbon Species and Stellar Type on Climates of Terrestrial Planets
topic Earth and Planetary Astrophysics
Atmospheric and Oceanic Physics
url https://arxiv.org/abs/2508.05975