well - this is certainly definitive

Posted on: August 5, 2021 at 23:54:49 CT

It has been shown previously that the AMOC is currently at its weakest in more than a 1000 years. However, so far it has remained an open question whether the observed weakening corresponds to a change in the mean circulation state, or whether it is associated with an actual loss of dynamical stability. “The difference is crucial”, says Niklas Boers, “because the loss of dynamical stability would imply that the AMOC has approached its critical threshold, beyond which a substantial and in practice likely irreversible transition to the weak mode could occur.”

Long-term observational data of the strength of the AMOC does unfortunately not exist, but the AMOC leaves so-called fingerprints in sea-surface temperature and salinity patterns of the Atlantic ocean. “A detailed analysis of these fingerprints in eight independent indices now suggests that the AMOC weakening during the last century is indeed likely to be associated with a loss of stability,” says Boers. ”The findings support the assessment that the AMOC decline is not just a fluctuation or a linear response to increasing temperatures but likely means the approaching of a critical threshold beyond which the circulation system could collapse.”

"remained an open question"
"data of the strength of the AMOC does unfortunately not exist"
"AMOC weakening during the last century"