Deep ocean early warning signals of an Atlantic MOC collapse

TL;DR

This paper introduces a new climate network-based indicator for early warning of Atlantic MOC collapse, emphasizing the importance of spatial resolution in deep ocean monitoring for timely detection.

Contribution

It presents a novel indicator based on climate network reconstruction that improves early detection of MOC collapse by monitoring spatial changes in deep ocean circulation.

Findings

The new indicator effectively signals approaching MOC collapse.

Increased spatial resolution enhances early warning capabilities.

Optimal measurement locations can be identified for better monitoring.

Abstract

The Atlantic Meridional Overturning Circulation (MOC) is a crucial part of the climate system because of its associated northward heat transport. The present-day MOC is sensitive to freshwater anomalies and may collapse to a state with a strongly reduced northward heat transport. A future collapse of the Atlantic MOC has been identified as one of the most dangerous tipping points in the climate system. It is therefore crucial to develop early warning indicators for such a potential collapse based on relatively short time series. So far, attempts to use indicators based on critical slowdown have been marginally successful. Based on complex climate network reconstruction, we here present a promising new indicator for the MOC collapse that efficiently monitors spatial changes in deep ocean circulation. Through our analysis of the performance of this indicator we formulate optimal locations of measurement of the MOC to provide early warning signals of a collapse. Our results imply that an increase in spatial resolution of the Atlantic MOC observations (i.e., at more sections) can improve early detection, because the spatial coherence in the deep ocean arising near the transition is better captured.