from NoTricksZone
Author: P. Gosselin
By Frank Bosse of Climate News
The “collapse” of the AMOC (Atlantic Overturning Circulation) cannot be “calculated” at all. We have reported on several AMOC forecasts here, most recently here and here .
Now, there's an interesting twist to the once “famous” study (DD23 below) which predicts AMOC collapse between 2025 and 2095 with 95% confidence!
It actually existed when the preprint appeared in September 2023, only about 3 months after the publication of DD23. Now officially published in the journal Science Advances (BY24 below). The title is meaningful:
Uncertainties are too great to determine 'tipping point times' for major components of the Earth system based on historical data.
A longer section of the current paper is devoted to DD23. Using only the HadiSST1 data set, she drew (also very) far-reaching conclusions from the SST (sea surface temperature) of the Atlantic Subpolar Gyre using variance and autocorrelation measurements. BY24 found that this was not allowed because sea surface temperatures there were not simply observed when these data were not available at the required spatial and temporal resolution. Something is added and in principle it is a model.
As of the 24th, it is now calculated that when using different data products (for example, NASA's ERSSTv5 with other “filling methods”), very different “AMOC collapse times” are determined: “between 2000 and infinity”!
Since all sea surface temperature data products include real observations, it ultimately just depends on how the observations are “supplemented” with models to determine the collapse time. This is clearly nonsense and the results are sensitive to the material used.
So whenever you read about any “tipping point” times: in fact, they cannot be determined at all because we don't have enough reliable information about the system (yet).
“The last generation… before the tipping point” – as the full name of the movement goes – will this also be the case? Its name is inherently unscientific. Bad news for “science followers”!
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