The Atlantic Meridional Overturning Circulation (AMOC) is at its weakest of the last millennium and is projected to further weaken over the coming decades, with the risk of a collapse over the coming century non negligible. The geologic record provides examples of rapid and large AMOC variations, with phases of AMOC weakening, preceding an AMOC shutdown. One key question is whether CO2-driven AMOC weakening is reversible, or whether it represents a tipping point, which might lead to an AMOC collapse. The study by Willeit et al. offers a new diagnostic that is simple to implement and allows for comparing AMOC stability between different models, as well as different time periods. This offers a powerful new tool in understanding the conditions for AMOC stability, and thus the AMOC future.