# Climate sensitivity to ozone and its relevance on the habitability of Earth-like planets

## TL;DR

This study uses a global climate model to show that atmospheric ozone significantly influences Earth's climate sensitivity, increasing surface temperature and reducing the habitable solar irradiance threshold.

## Contribution

First to quantify ozone's impact on climate sensitivity and habitability thresholds of Earth-like planets under increasing solar radiation.

## Key findings

- Ozone increases surface temperature by 7 K under the same solar irradiance.
- Ozone lowers the moist greenhouse threshold to 1572 W/m^2.
- Ozone reduces the maximum habitable solar irradiance for Earth-like planets.

## Abstract

Atmospheric ozone plays an important role on the temperature structure of the atmosphere. However, it has not been included in previous studies on the effect of an increasing solar radiation on the Earth's climate. Here we study the climate sensitivity to the presence/absence of ozone with an increasing solar forcing for the first time with a global climate model. We show that the warming effect of ozone increases both the humidity of the lower atmosphere and the surface temperature. Under the same solar irradiance, the mean surface temperature is 7 K higher than in an analog planet without ozone. Therefore, the moist greenhouse threshold, the state at which water vapor becomes abundant in the stratosphere, is reached at a lower solar irradiance (1572 Wm^-2 with respect to 1647 Wm^-2 in the case without ozone). Our results imply that ozone reduces the maximum solar irradiance at which Earth-like planets would remain habitable.