Resilience of the Atlantic Meridional Overturning Circulation

TL;DR

This paper introduces a novel probabilistic framework to assess the resilience of the Atlantic Meridional Overturning Circulation (AMOC), accounting for its multi-stable nature and external forcing, with potential applications to other dynamical systems.

Contribution

It presents a new rare event-based approach to quantify AMOC resilience and extends it to estimate transition probabilities under external forcing conditions.

Findings

The proposed measure effectively assesses AMOC resilience.

The framework can estimate transition probabilities conditioned on external forcing.

It defines a probabilistic safe operating space for the AMOC.

Abstract

We address the issue of resilience of the Atlantic Meridional Overturning Circulation (AMOC) given the many indications that this dynamical system is in a multi-stable regime. A novel approach to resilience based on rare event techniques is presented which leads to a measure capturing `resistance to change` and `ability to return' aspects in a probabilistic way. The application of this measure to a conceptual model demonstrates its suitability for assessing AMOC resilience but also shows its potential use in many other non-autonomous dynamical systems. This framework is then extended to compute the probability that the AMOC undergoes a transition conditioned on an external forcing. Such conditional probability can be estimated by exploiting the information available when computing the resilience of this system. This allows us to provide a probabilistic view on safe operating spaces by defining a conditional safe operating space as a subset of the parameter space of the (possibly transient) imposed forcing.