Resilience of Snowball Earth to Stochastic Events

TL;DR

This study uses an energy balance climate model to assess whether stochastic events like asteroid impacts or supervolcanoes could end Snowball Earth states, concluding that such events are generally insufficient unless background CO2 levels are already high.

Contribution

The paper demonstrates through modeling that Snowball Earth states are resilient to stochastic events unless pre-existing high CO2 levels are present.

Findings

Large impacts and supervolcanoes alone cannot end Snowball Earth.

High background CO2 levels are necessary for stochastic events to trigger deglaciation.

Snowball Earth states show resilience against stochastic perturbations.

Abstract

Earth went through at least two periods of global glaciation (i.e., ``Snowball Earth'' states) during the Neoproterozoic, the shortest of which (the Marinoan) may not have lasted sufficiently long for its termination to be explained by the gradual volcanic build-up of greenhouse gases in the atmosphere. Large asteroid impacts and supervolcanic eruptions have been suggested as stochastic geological events that could cause a sudden end to global glaciation via a runaway melting process. Here, we employ an energy balance climate model to simulate the evolution of Snowball Earth's surface temperature after such events. We find that even a large impactor (diameters of $d \sim 100\,\mathrm{km}$) and the supervolcanic Toba eruption ($74\,\mathrm{kyr}$ ago), are insufficient to terminate a Snowball state unless background CO$_2$ has already been driven to high levels by long-term outgassing. We suggest, according to our modeling framework, that Earth's Snowball states would have been resilient to termination by stochastic events.