# Mechanisms leading to a warmer climate on high obliquity planets

## TL;DR

High obliquity planets tend to be warmer than low obliquity ones due to mechanisms beyond ice-albedo feedback, involving cloud effects and seasonal variations, even at high insolation levels.

## Contribution

This study identifies that cloud radiation effects and seasonal variations, not just ice-albedo feedback, drive warmer climates on high obliquity planets across various insolation levels.

## Key findings

- Ice-albedo feedback is not the sole mechanism for warmth on high obliquity planets.
- Cloud radiation effects significantly influence surface temperature differences.
- Seasonal variation impacts the lag between surface temperature and insolation, affecting climate warmth.

## Abstract

A consistent finding of high obliquity simulations is that they are warmer than their low obliquity counterparts when the climate is cold. Ice-albedo feedback has been suggested as a possible mechanism. In this study, we find that warmer climate under high obliquity holds with varying insolations, including almost ice-free conditions. We try to understand the mechanisms through a series of feedback suppression experiments. Turning off the ice-albedo feedback, the temperature contrast between high and low obliquity remains significant, but it vanishes when the cloud radiation effects or the seasonal variation is turned off. This suggests the warmer climate on high obliquity planets does not rely completely on the existence of ice, and therefore holds at high insolation. In that regime, the surface temperature, and hence the cloud formation, lags behind the substellar point, leading to inefficient sunlight reflection and warmer climate.