The Moist Greenhouse is Sensitive to Stratospheric Temperature

TL;DR

This paper demonstrates that the moist greenhouse temperature threshold is highly sensitive to stratospheric temperatures, impacting planetary habitability assessments, especially for M-star planets, and highlights the need for collaborative modeling efforts.

Contribution

It reveals the importance of stratospheric temperature in determining the moist greenhouse threshold, bridging gaps between 1-D and 3-D climate models for M-star planets.

Findings

Stratospheric temperature significantly influences the moist greenhouse threshold.

Higher stratospheric temperatures in models explain discrepancies between 1-D and 3-D results.

Implications for habitability are substantial if high stratospheric temperatures are common.

Abstract

In this Research Note, I use my single-column climate model to explicitly show that the moist greenhouse surface temperature threshold is sensitive to stratospheric temperature. I argue that this explains most of the discrepancy between 1-D and recent 3-D computations of the moist greenhouse threshold for M-star planets given that calculated stratospheric (and upper atmospheric) temperatures are higher than what are usually assumed in 1-D calculations. I suggest that collaborations between the two sets of modelers would lead to greater understanding of the moist greenhouse threshold. I also discuss implications for habitability if high stratospheric temperatures are a common feature on M-star planets near the inner edge.