Greenhouse warming potential of a suite of gas species on early Mars evaluated using a radiative-convective climate model

TL;DR

This study evaluates the warming potential of various greenhouse gases on early Mars using a radiative-convective climate model, identifying key gases that could have contributed to past warming despite their vulnerabilities.

Contribution

It provides a comprehensive survey of all known greenhouse gases' warming effects on early Mars and offers a detailed database for future research.

Findings

H2O2, HNO3, NH3, SO2, and C2H4 cause significant warming at ~0.1 ppmv.

Highly effective gases are often condensable, soluble, and photolytically vulnerable.

The warming potential database is publicly available online.

Abstract

Abundant geomorphological and geochemical evidence of liquid water on the surface of early Mars during the late Noachian and early Hesperian periods needs to be reconciled with a fainter young Sun. While a dense CO2 atmosphere and related warming mechanisms are potential solutions to the early Mars climate problem, further investigation is warranted. Here, we complete a comprehensive survey of the warming potential of all known greenhouse gases and perform detailed calculations for 15 different minor gas species under early Martian conditions. We find that of these 15 species, H2O2, HNO3, NH3, SO2, and C2H4 cause significant greenhouse warming at concentrations of ~0.1 ppmv or greater. However, the most highly effective greenhouse gas species also tend to be more condensable, soluble and vulnerable to photolytic destruction. To provide a reference for future atmospheric evolution and photochemical studies, we have made our warming potential database freely available online.