The Snowball Earth transition in a climate model with drifting parameters

TL;DR

This study uses a climate model to explore the Snowball Earth transition driven by gradual changes in solar input, revealing the potential for irreversible climate tipping points and probabilistic recoveries.

Contribution

It introduces a parameter drift scenario in a climate model to analyze the stability and transition dynamics between warm and Snowball Earth states.

Findings

Climate system exhibits bistability with two stable states.

Transition from warm to Snowball Earth is inevitable under decreasing solar constant.

Reverse transition from Snowball to warm climate is possible with a certain probability.

Abstract

Using an intermediate complexity climate model (Planet Simulator), we investigate the so-called Snowball Earth transition. For certain values of the solar constant, the climate system allows two different stable states: one of them is the Snowball Earth, covered by ice and snow, and the other one is today's climate. In our setup, we consider the case when the climate system starts from its warm attractor (the stable climate we experience today), and the solar constant is decreased continuously in finite time, according to a parameter drift scenario, to a state, where only the Snowball Earth's attractor remains stable. This induces an inevitable transition, or climate tipping from the warm climate. The reverse transition is also discussed. Increasing the solar constant back to its original value on individual simulations, we find that the system stays stuck in the Snowball state. However, using ensemble methods i.e., using an ensemble of climate realizations differing only slightly in their initial conditions we show that the transition from the Snowball Earth to the warm climate is also possible with a certain probability. From the point of view of dynamical systems theory, we can say that the system's snapshot attractor splits between the warm climate's and the Snowball Earth's attractor.