Deep ocean early warning signals of an Atlantic MOC collapse

A future collapse of the Atlantic Meridional Overturning Circulation (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. Key Points Develop an early warning indicator of MOC collapse based on complex networksDemonstrate its performance using the data from a GCM that shows MOC collapseFormulate optimal observation locations from quality measures of the indicator