AMOC Collapse Depends Entirely On Models…Will Occur Sometime Between Now And Infinity

AMOC Uncertainties

By Frank Bosse at Klimanachrichten

A “collapse” of the AMOC (Atlantic overturning circulation) cannot be “calculated” at all. We have reported on several projections of the AMOC here, most recently here and here.

There is now an interesting twist to the once very “celebrated” study (DD23 below), which predicted a collapse of the AMOC between 2025 and 2095 with 95% certainty!

It actually already existed in September 2023 when the preprint appeared, i.e. only around 3 months after the publication of DD23. Now the official publication in the journal “Science Advances” (BY24 below). The title speaks volumes:

The uncertainties are too large to determine ‘tipping point times’ of major Earth system components from historical data.”

Longer sections of the current paper are dedicated to DD23. She had drawn (far too) far-reaching conclusions from the SST (sea surface temperatures) of the “Atlantic Subpolar Gyre” with the help of variance and autocorrelation determinations, using the HadiSST1 data set alone. This was not permissible, BY24 finds, because the SSTs there are NOT simply observations when these are not available in the required spatial and temporal resolution. Something is added, in principle it is a model.

In BY 24 it is now calculated that when using different data products (e.g. also NASA’s ERSSTv5 with other “infill methods”) very different “collapse times of the AMOC” are determined: “between 2000 and infinity”!

Since the real observations are included in all SST data products, in the end it only depends on how the observations are “supplemented” using a model in order to determine a collapse time. This is obviously nonsense, the results are sensitive to the data used.

So whenever you read about any “tipping point” times: In truth, they cannot be determined at all because we do not (yet) have enough reliable information on the system.

Will this also be the case with “The last generation…before the tipping points” – as the movement is called in full? Its name is inherently unscientific. Bad news for “science followers”!