High pCO$_2$ reduces sensitivity to CO$_2$ perturbations on temperate, Earth-like planets throughout most of habitable zone

R. J. Graham

doi:10.1089/ast.2020.2411

paper

High pCO $_{2}$ reduces sensitivity to CO $_{2}$ perturbations on temperate, Earth-like planets throughout most of habitable zone

arXiv:2104.01224 · doi:10.1089/ast.2020.2411

Abstract

The nearly logarithmic radiative impact of CO $_{2}$ means that planets near the outer edge of the liquid water habitable zone (HZ) require $\sim$ 10 $^{6}$ x more CO $_{2}$ to maintain temperatures conducive to standing liquid water on the planetary surface than their counterparts near the inner edge. This logarithmic radiative response also means that atmospheric CO $_{2}$ changes of a given mass will have smaller temperature effects on higher pCO $_{2}$ planets. Ocean pH is linked to atmospheric pCO $_{2}$ through seawater carbonate speciation and calcium carbonate dissolution/precipitation, and the response of pH to changes in pCO $_{2}$ also decreases at higher initial pCO $_{2}$ . Here, we use idealized climate and ocean chemistry models to demonstrate that CO $_{2}$ perturbations large enough to cause catastrophic changes to surface temperature and ocean pH on low-pCO $_{2}$ planets in the innermost region of the HZ are likely to have much smaller effects on planets with higher pCO $_{2}$ . Major bouts of extraterrestrial fossil fuel combustion or volcanic CO $_{2}$ outgassing on high-pCO $_{2}$ planets in the mid-to-outer HZ should have mild or negligible impacts on surface temperature and ocean pH. Owing to low pCO $_{2}$ , Phanerozoic Earth's surface environment may be unusually volatile compared to similar planets receiving lower instellation.

Submitted November 30, 2020; Reviews received March 23rd, 2021; Resubmitted April 2, 2021

High pCO $_{2}$ reduces sensitivity to CO $_{2}$ perturbations on temperate, Earth-like planets throughout most of habitable zone

Abstract

References in corpus (9)

Cited by in corpus (5)

High pCO2​ reduces sensitivity to CO2​ perturbations on temperate, Earth-like planets throughout most of habitable zone

Abstract

References in corpus (9)

Cited by in corpus (5)

High pCO $_{2}$ reduces sensitivity to CO $_{2}$ perturbations on temperate, Earth-like planets throughout most of habitable zone