A new indicator for the AMOC strength still gives no indication of an imminent collapse

Abstract

The results of a recent simulation with a complex global climate model suggest that the overturning component of the freshwater transport at the southern boundary of the Atlantic could be used as an early-warning indicator of an AMOC collapse. However, there are two shortcomings. Firstly, the simulation is based on some implausible assumptions. It is therefore not clear whether this new indicator will still be helpful in a more realistic setting. Secondly, the statistical methods employed in the simulation work only for time series that are much longer than the currently available historical series. As not much can be done in the short term about the first issue, this paper focuses on the second issue. It is shown that it is possible to use alternative statistical methods that can do the job at least as well and, moreover, are also suitable for short series. Applying these more appropriate methods to historical data obtained with an ocean reanalysis system, no indication of an imminent AMOC collapse is found.