Even though the new data would seem to diminish the gravity of recent AMOC trends in the North Atlantic,
a decrease is still a decrease.
And Volkov and colleagues stressed the importance of maintaining programs such as RAPID:
… the likelihood of a future AMOC slowdown and the importance of both the [Florida Current] and the AMOC in the regional and global climate variability emphasizes the value of sustained observations in the Florida Straits and in the subtropical North Atlantic at ~26.5°N.
The existing records are just starting to resolve decadal-scale signals relevant to climate variability.
The observations-oriented scientists who assess AMOC in the wild and confront the raw data agree that AMOC will weaken as the planet warms,
but they tend to be cautious about putting out timelines for AMOC collapse.
Ben Moat, the co-chief scientist of RAPID, posted these views in September 2024 in a news release from the UK National Centre for Oceanography:
"Prior to starting the RAPID project in 2004, changes in large-scale ocean circulation were thought to happen very slowly,
perhaps on timescales of 100 years.
Observations made within the first year of the RAPID array showed the ocean circulation changed on hourly and daily timescales.
The results made fundamental changes in the way we understand how the ocean circulates heat around the planet.
While we have made some revolutionary steps already, the big unanswered questions are about the predicted weakening of the AMOC.
We think it will weaken, but by how much and when is still uncertain."
Eleanor Frajka-Williams, head of experimental oceanography at the University of Hamburg, was among the organizers of a 2023 workshop on AMOC observation needs in a changing climate.
Summarizing the mood of the meeting, she posted on X:
“From the observational (rather than proxy) record, a majority agreed that we don’t yet know how the AMOC will respond to future anthropogenic [human-caused] change.”
A group of experts from the European Union’s EPOC
(Explaining and Predicting the Ocean Conveyor) project
also weighed in this year,
aiming to put recent papers in perspective:
"Over the years the pendulum has swung from a marked AMOC decline/shutdown being considered likely to this being an unlikely scenario.
Currently, the prevalent view is somewhere between the two. …
The AMOC’s likely future fate remains an important question, though one that we cannot yet answer based on our current level of understanding."
So in summary, we have at least some reassurance from the North Atlantic data that a full-on AMOC collapse hasn’t begun.
And it’s unlikely that any future collapse would reach its end point any sooner than the early to mid-2100s.
Yet there’s also legitimate concern
– stoked by recent work from climate modelers and statisticians
– that a tipping point toward eventual collapse could arrive as soon as the next several decades,
especially if fossil-fuel emissions aren’t cut sharply.
In part two of this two-part post, we’ll look at some of the new research on early-warning signs of AMOC collapse,
what those scientists and other assessments are telling us about the threat,
and how we can help limit the odds of an AMOC collapse happening in the first place.
https://yaleclimateconnections.org/2024/12/atlantic-circulation-collapse-new-clues-on-the-fate-of-a-crucial-conveyor-belt/
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