Comparison of Two Analytic Energy Balance Models Shows Stable Partial Ice Cover Possible for Any Obliquity

TL;DR

This paper compares two energy balance models with explicit obliquity dependence, demonstrating that stable partial ice cover can exist at any obliquity, and analyzes the conditions leading to Snowball state transitions on planets.

Contribution

It introduces a comparative analysis of two analytic models with different heat transport methods, showing the potential for stable partial ice cover at any obliquity and quantifying Snowball transition severity.

Findings

Stable partial ice cover possible at any obliquity.

Snowball transition severity increases with albedo contrast and energy transport.

Transition likelihood varies between models depending on parameters.

Abstract

In this study, we compare two analytic energy balance models with explicit dependence on obliquity to study the likelihood of different stable ice configurations. We compare the results of models with different methods of heat transport and different insolation distributions. We show that stable partial ice cover is possible for any obliquity, provided the insolation distribution is sufficiently accurate. Additionally, we quantify the severity of the transition to the Snowball state as different model parameters are varied. In accordance with an earlier study, transitions to the Snowball state are more severe for higher values of the albedo contrast and energy transport across latitudes in both model; however, we find that the Snowball transition is not equally likely across both models. This work is general enough to apply to any rapidly rotating planet and could be used to study the likelihood of Snowball transitions on planets within the habitable region of other stars.