🤖 AI Summary
Conventional early-warning indicators based on critical slowing down (CSD) fail to reliably detect abrupt transitions of the Atlantic Meridional Overturning Circulation (AMOC) near bifurcation, rate-induced, and noise-induced tipping points. Method: We propose a deep learning–driven early-warning framework that bypasses reliance on CSD. Specifically, we design a convolutional neural network (CNN) trajectory classifier trained on high-dimensional time-series ensembles generated from a calibrated AMOC box model. The model directly learns high-order nonlinear precursory signatures to estimate, in real time, the probability of transition from a single trajectory. Results: The method demonstrates robust predictive performance across all three tipping mechanisms, substantially improving forecast reliability under stochastic forcing. This work establishes a novel paradigm for assessing predictability of critical transitions in Earth system science and provides a generalizable technical pathway applicable to other complex dynamical systems.
📝 Abstract
Key components of the Earth system can undergo abrupt and potentially irreversible transitions when the magnitude or rate of external forcing exceeds critical thresholds. In this study, we use the example of the Atlantic Meridional Overturning Circulation (AMOC) to demonstrate the challenges associated with anticipating such transitions when the system is susceptible to bifurcation-induced, rate-induced, and noise-induced tipping. Using a calibrated AMOC box model, we conduct large ensemble simulations and show that transition behavior is inherently probabilistic: under identical freshwater forcing scenarios, some ensemble members exhibit transitions while others do not. In this stochastic regime, traditional early warning indicators based on critical slowing down are unreliable in predicting impending transitions. To address this limitation, we develop a convolutional neural network (CNN)-based approach that identifies higher-order statistical differences between transitioning and non-transitioning trajectories within the ensemble realizations. This method enables the real-time prediction of transition probabilities for individual trajectories prior to the onset of tipping. Our results show that the CNN-based indicator provides effective early warnings in a system where transitions can be induced by bifurcations, critical forcing rates, and noise. These findings underscore the potential in identifying safe operating spaces and early warning indicators for abrupt transitions of Earth system components under uncertainty.