Table 1 Parameter ranges for our numerical model.

From: Carbonate-silicate cycle predictions of Earth-like planetary climates and testing the habitable zone concept

Parameter

Parameter description

Range

Scaling

Units

\({F}_{{\rm{out}}}^{{\rm{mod}}}\)

Modern CO2 outgassing flux

6–10

 

Tmol C yr−1

n

Carbonate precipitation coefficient

1–2.5

\(\propto {\left[{{\rm{CO}}}_{3}^{2-}\right]}^{n}\)

 

x

Modern seafloor dissolution relative to precipitation

0.5–1.5

\(\propto x{F}_{{\rm{out}}}^{{\rm{mod}}}\)

 

Te

E-folding temperature factor for continental weathering

10–40

 

K

α

Power law exponent for CO2 dependence of continental silicate weathering

0.1–0.5

\(\propto {\left({{\rm{pCO}}}_{2}\right)}^{\alpha }\)

 

ξ

Power law exponent for CO2 dependence of continental carbonate weathering

0.1–0.5

\(\propto {\left({{\rm{pCO}}}_{2}\right)}^{\xi }\)

 

fland

Land fraction compared to modern Earth

0–1

  

Sthick

Ocean sediment thickness relative to modern Earth

0.2–1

  

\({F}_{{\rm{carb}}}^{{\rm{mod}}}\)

Modern continental carbonate weathering

7–14

 

Tmol C yr−1

fbio

Biological weathering compared to modern Earth

0–1

  

\({a}_{{\rm{grad}}}\)

Surface to deep ocean temperature gradient scaling

0.8–1.4

\(\propto {a}_{{\rm{grad}}}{T}_{{\rm{s}}}\)

 

γ

Power law exponent for pH dependence of seafloor dissolution

0–0.5

\(\propto {\left(\left[{{\rm{H}}}^{+}\right]\right)}^{\gamma }\)

 

β

Power law exponent for seafloor spreading rate

0–0.2

Qβ

 

m

Exponent for outgassing dependence on crustal production

1–2

Qm

 

Ebas

Seafloor dissolution activation energy

60–100

 

kJ mol−1

nout

Exponent for internal heat with time

0–0.73

see Eq. (10)

 

τ

Planet age (see Eq. (10))*

0–10

 

Gyr

S

Incident flux relative to modern Earth*

0.35–1.05

  
  1. Parameters are dimensionless unless otherwise described. The fourth column shows how scaling parameters impact the model, where Ts is the surface temperature in K and Q is the internal heat of the planet relative to the modern Earth (see Eq. (10) for Q). Unless otherwise noted, each parameter range is justified in the original model derivation for the Earth through time21.
  2. *The justification for this parameter is given in the Methods, subsection “Numerical carbonate–silicate cycle modeling”.