An approach for projecting the timing of abrupt winter Arctic sea ice loss

TL;DR

This paper proposes a new method to predict the timing of abrupt winter Arctic sea ice loss due to climate change by analyzing deviations from equilibrium in time-dependent CO2 experiments, avoiding the need for long simulations.

Contribution

It introduces an approach to identify and project sea-ice tipping points using short-term CO2 experiments, bypassing computationally expensive equilibrium model runs.

Findings

A few time-dependent CO2 experiments can predict sea-ice tipping points.

Single slow-changing CO2 experiments are ineffective for detecting steady-state changes.

The method offers a practical alternative for climate models to identify potential abrupt ice loss.

Abstract

Abrupt and irreversible winter Arctic sea-ice loss may occur under anthropogenic warming due to the collapse of a sea-ice equilibrium at a threshold value of CO$_2$, commonly referred to as a tipping point. Previous work has been unable to conclusively identify whether a tipping point in Arctic sea ice exists because fully-coupled climate models are too computationally expensive to run to equilibrium for many CO$_2$ values. Here, we explore the deviation of sea ice from its equilibrium state under realistic rates of CO$_2$ increase to demonstrate how a few time-dependent CO$_2$ experiments can be used to predict the existence and timing of sea-ice tipping points without running the model to steady-state. This study highlights the inefficacy of using a single experiment with slow-changing CO$_2$ to discover changes in the sea-ice steady-state, and provides an alternate method that can be developed for the identification of tipping points in realistic climate models.