Outer Limits of the Habitable Zones in Terms of Climate Mode and Climate Evolution of Earth-like Planets

Kadoya, Shintaro; Tajika, Eiichi

doi:10.3847/1538-4357/ab0aef

Cited by 25 publications

(41 citation statements)

References 45 publications

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“…A planet that has a carbonate‐silicate cycle should shift to a warm state after a snowball state because of atmospheric

{CO}_{2}

that accumulates when continental weathering ceases to melts the ice sheet (Hoffman et al, ). However, recent studies suggest that under a low insolation even within the HZ limits, such a recovery from a snowball state is prevented owing to the condensation of

{CO}_{2}

ice (Turbet et al, ) and/or ice albedo feedback (Kadoya & Tajika, ). This indicates that the insolation needed at the outer limit of the HZ is higher (i.e., the HZ is narrower) than previous estimates (Kasting et al, ; Kopparapu et al, ) if a snowball planet is common.…”

Section: Discussionmentioning

confidence: 99%

Probable Cold and Alkaline Surface Environment of the Hadean Earth Caused by Impact Ejecta Weathering

Kadoya

Krissansen‐Totton

Catling

2020

Geochem Geophys Geosyst

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Constraining the surface environment of the early Earth is essential for understanding the origin and evolution of life. The release of cations from silicate weathering depends on climatic temperature and pCO 2 , and such cations sequester CO 2 into carbonate minerals in or on the seafloor, providing a stabilizing feedback on climate. Previous studies have suggested that this carbonate-silicate cycle can keep the early Earth's surface temperature moderate by increasing pCO 2 to compensate for the faint young Sun. However, the Hadean Earth experienced a high meteorite impactor flux, which produced ejecta that is easily weathered by carbonic acid. In this study, we estimated the histories of surface temperature and ocean pH during the Hadean and early Archean using a new model that includes the weathering of impact ejecta, empirically justified seafloor weathering, and ocean carbonate chemistry. We find that relatively low pCO 2 and surface temperatures are probable during the Hadean, for example, at 4.3 Ga, log 10 (pCO 2 ) (in bar) is −2.21 +3.01 −2.54 [2 ] and temperature is 259.2 +84.1 −14.4 [2 ] K. Such a low pCO 2 would result in a circumneutral to basic pH of seawater, for example, 7.90 +1.21 −1.69 [2 ] at 4.3 Ga.A probably cold and alkaline marine environment is associated with a high impact flux. Hence, if there was an interval of an enhanced impact flux, that is, Late Heavy Bombardment, similar conditions may have existed in the early Archean. Therefore, if the origin of life occurred in the Hadean, life likely emerged in a cold global environment and probably spread into an alkaline ocean. Plain Language SummaryThe Earth's environment during the Hadean eon, 4.5 to 4 billion years ago, is obscured by a lack of geological evidence. However, life likely arose then, so improving our knowledge of the early environment is essential for understanding the origin and evolution of life. Here, we build a geological carbon cycle model that simulates the early surface environment and generates probability distributions for the level of atmospheric carbon dioxide (CO 2 ), average surface temperature, and ocean pH over time. During the Hadean, CO 2 dissolved in water is consumed by reacting with material ejected from meteorite impacts, so CO 2 levels tend to be low and the greenhouse effect weak. The consequences are low surface temperature and alkaline seawater. The probability that the surface temperature was lower than the freezing point of water and that seawater pH exceeded 7 is 70% at 4.3 billion years ago. Thus, if life began in the Hadean, it likely emerged in a cold global environment, and early life may have spread into an alkaline ocean. Key Points:• We estimate the range of pCO 2 , surface temperature, and ocean pH in the Hadean and Archean • A cold, Hadean surface environment and circumneutral to basic ocean pH is likely because of impact ejecta weathering • The origin of life may have occurred in a cold environment, and early life may have spread into a cold alkaline ocean Supporting Information:• Supporti...

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“…A planet that has a carbonate‐silicate cycle should shift to a warm state after a snowball state because of atmospheric

{CO}_{2}

{CO}_{2}

Section: Discussionmentioning

confidence: 99%

Probable Cold and Alkaline Surface Environment of the Hadean Earth Caused by Impact Ejecta Weathering

Kadoya

Krissansen‐Totton

Catling

2020

Geochem Geophys Geosyst

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“…Previous studies provide formulations of climate models (e.g., Walker et al 1981;Kasting et al 1993). Recently, Kopparapu et al (2013Kopparapu et al ( , 2014 per-formed 1D radiative-convective calculations to obtain T as a function of P CO2 , α and S. Studies such as Haqq-Misra et al 2016and Kadoya & Tajika (2019) provide fitting functions to the models of Kopparapu et al (2013Kopparapu et al ( , 2014. We use the fitting function provided by Kadoya & Tajika (2019) to couple T in the range 150−350 K with P CO2 in the range 10 −5 − 10 bar.…”

Section: Climate Modelmentioning

confidence: 99%

“…Recently, Kopparapu et al (2013Kopparapu et al ( , 2014 per-formed 1D radiative-convective calculations to obtain T as a function of P CO2 , α and S. Studies such as Haqq-Misra et al 2016and Kadoya & Tajika (2019) provide fitting functions to the models of Kopparapu et al (2013Kopparapu et al ( , 2014. We use the fitting function provided by Kadoya & Tajika (2019) to couple T in the range 150−350 K with P CO2 in the range 10 −5 − 10 bar. For α = 0.3 (present-day albedo of Earth) and S = 1360 W m −2 (present-day solar flux), the Kadoya & Tajika (2019) fitting function results in T between 280−350 K for P CO2 between 10 µbar and 0.5 bar (see Appendix E for details).…”

Section: Climate Modelmentioning

confidence: 99%

“…We use the fitting function provided by Kadoya & Tajika (2019) to couple T in the range 150−350 K with P CO2 in the range 10 −5 − 10 bar. For α = 0.3 (present-day albedo of Earth) and S = 1360 W m −2 (present-day solar flux), the Kadoya & Tajika (2019) fitting function results in T between 280−350 K for P CO2 between 10 µbar and 0.5 bar (see Appendix E for details).…”

Section: Climate Modelmentioning

confidence: 99%

“…A climate model provides a relation between the surface temperature T , the CO 2 partial pressure P CO2 , top-of-atmosphere stellar flux S and planetary albedo α. Kadoya & Tajika (2019) provide a fitting function to the climate model of Kopparapu et al (2013Kopparapu et al ( , 2014 which is valid for T in the range 150−350 K with P CO2 in the range 10 −5 − 10 bar at saturated H 2 O and 1 bar N 2 . The fitting function is given by F OLR (T, P CO2 ) = I 0 + T B P t , (E7)…”

Section: E Climate Modelsmentioning

confidence: 99%

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Lithologic Controls on Silicate Weathering Regimes of Temperate Planets

Hakim¹,

Bower²,

Tian³

et al. 2022

Preprint

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Weathering of silicate rocks at a planetary surface can draw down CO 2 from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide an essential negative feedback to the carbonate-silicate cycle (carbon cycle) to maintain clement climates on Earth and potentially similar temperate exoplanets. We implement thermodynamics to determine weathering rates as a function of surface lithology (rock type). These rates provide upper limits that allow estimating the maximum rate of weathering in regulating climate. This modeling shows that the weathering of mineral assemblages in a given rock, rather than individual minerals, is crucial to determine weathering rates at planetary surfaces. By implementing a fluid-transport controlled approach, we further mimic chemical kinetics and thermodynamics to determine weathering rates for three types of rocks inspired by the lithologies of Earth's continental and oceanic crust, and its upper mantle. We find that thermodynamic weathering rates of a continental crust-like lithology are about one to two orders of magnitude lower than those of a lithology characteristic of the oceanic crust. We show that when the CO 2 partial pressure decreases or surface temperature increases, thermodynamics rather than kinetics exerts a strong control on weathering. The kinetically-and thermodynamically-limited regimes of weathering depend on lithology, whereas, the supply-limited weathering is independent of lithology. Our results imply that the temperature-sensitivity of thermodynamically-limited silicate weathering may instigate a positive feedback to the carbon cycle, in which the weathering rate decreases as the surface temperature increases.

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Early Habitability and Crustal Decarbonation of a Stagnant‐Lid Venus

et al. 2021

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The evolution of Venus is still in many ways a mystery. Despite its similarity to Earth in terms of size and bulk composition (e.g., Lécuyer et al., 2000), the atmospheric 2 CO E mass of Venus is larger by more than five orders of magnitude (Donahue & Pollack, 1983). Whether Venus' atmosphere was 2 CO E -rich early in its evolution, or whether, and how, it diverged from Earth's atmosphere later in its evolution is a matter of debate (e.g.,

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Outer Limits of the Habitable Zones in Terms of Climate Mode and Climate Evolution of Earth-like Planets

Cited by 25 publications

References 45 publications

Probable Cold and Alkaline Surface Environment of the Hadean Earth Caused by Impact Ejecta Weathering

Probable Cold and Alkaline Surface Environment of the Hadean Earth Caused by Impact Ejecta Weathering

Lithologic Controls on Silicate Weathering Regimes of Temperate Planets

Early Habitability and Crustal Decarbonation of a Stagnant‐Lid Venus

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