New AMOC study: Critical ocean current has not declined in the last 60 years

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SaxManSteve@reddit

It's worth clarifying that because of methodological limitations, this study could not use data past 2017 in their analysis. Their analysis covered the period between 1963-2017. This doesn't take away from the significance of their findings, especially when you consider that most studies claiming that AMOC is weakening also use data from the same time window(roughly 1950s-2020). For example, this paper used data starting from 1950 and concluded that there had been a persistent weakening of AMOC since the mid-twentieth century. They even offer a specific rate of slowdown per decade.

The fact that conflicting results are being published about the AMOC shouldn't surprise anyone. Climate science modeling is extremely complex. This is a normal part of what the scientific process is about.

For those who are worried about this potentially positive bit of climate science news, maybe it will help you sleep better at night knowing that the lead author of this paper --despite his findings-- said it is "virtually certain" that AMOC will decline. So crisis averted, collapse is still on the menu!

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stardustr3v3ri3@reddit

how is collapse still being on the menu a good thing?

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Airilsai@reddit

This study has already been posted and removed due to low quality. Your post title is misrepresenting the situation.

This study doesn't include the key period where we approach and begin to tip over 1.5, 2018-2024, which is where we expect to observe AMOC collapse starting. Ending the data at 2017 and saying everything is okay is ridiculous.

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SaxManSteve@reddit

Almost all the papers that show that the AMOC is weakening also use data from the years used in the paper above (1960s-2017). So it's not misleading. OP also just copied the title from the article.

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Airilsai@reddit

"Not declined in the last 60 years" includes the last 6 years, which is not included in the study. The title is misleading, by definition. Its not arguable, its literally just does "last 60 years" include the last 6 years, and does the study include the last 6 years?

The last 6 years of warming are THE critical period to be looking at.

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SaxManSteve@reddit

Thanks for bringing this up, i added a sticky to make sure this is clear.

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latepeaches@reddit (OP)

As u/saxmansteve said, I copied the title from the article. I was nervous that editorializing the title too much would go against the sub rules and thought it safest to leave it as it was. I’m also aware that this same study was submitted and removed from the sub about a day ago, but I didn’t see anything on the original post indicating why it was removed, so I figured I’d try.

To expand on what I said in my submission statement, I’m posting this to the sub because this paper came across my feed, and I didn’t know what to make of it. I’m not well-educated on the specifics current AMOC research and figured folks on this sub might know better. I also know that I won’t be the only person to come across this paper, and I feel it’s important to let the collapse community respond and vet the paper in a publicly accessible forum, should someone else find this research and not understand why its flawed/inaccurate; or have similar questions.

I understand that in today’s climate, posting information that contradicts commonly held beliefs or research may be seen as an endorsement of said information, but that was not the intent here. I am of the opinion that the AMOC may be weakening, like many systems that form/support our biosphere, and I am trying to arrive at a better understanding of the truth as a lay person. I appreciate your perspective and taking the time to comment.

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Ziprasidone_Stat@reddit

You understood correctly. I, too, came across it and was hoping someone would explain. The guy who responded to you gave enough of a summary for me to surmise it is a misleading report. So thanks for posting.

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The_Weekend_Baker@reddit

Most of the climate scientists I follow are embracing it, and now consider the previous "AMOC is shutting down" studies as being hype and doom. Not surprisingly, not all are on board with that.

https://bsky.app/profile/khaustein.bsky.social/post/3lfx2xivyyk2n

This, FWIW, is the response they should have. When you have 10 studies saying something and 1 saying something different, scientists should add that single study to all of the known science on the subject instead of being the absolute truth, because there's always a possibility that a study's methodology was flawed.

Because even Jens Terhaar qualified the study with: However, a so-far stable AMOC does not mean that the AMOC will not decline in the future. It is virtually certain that such a decline will happen, and its consequences will be dramatic.

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Useful_Divide7154@reddit

Just a thought - If 10 studies with very similar methodology say one thing and one other study with different methodology says another, you can’t automatically say that the 10 studies are more likely to be correct. It’s very likely that they were modeled off each other, virtually guaranteeing that the results produced are similar.

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The_Weekend_Baker@reddit

That's correct, which is why I said it should be added to the existing knowledge. What bothers me isn't the study, it's that scientists are largely accepting it as "the truth" so soon after its release.

It's not the kind of thing that happens in a field like physics. Dark energy, for example, is the proposed force that's not only driving cosmic expansion, but is causing it to expand at an accelerating rate. No one knows what it is, but it's generally accepted that it's there. There was a study published last month that essentially does away with dark energy:

The new evidence supports the "timescape" model of cosmic expansion, which doesn't have a need for dark energy because the differences in stretching light aren't the result of an accelerating universe but instead a consequence of how we calibrate time and distance.

https://phys.org/news/2024-12-dark-energy-doesnt-lumpy-universe.html

Did physicists see this new study and say, "Whew, that settles it. We don't have to worry about dark energy anymore because we have an explanation!" No, they didn't. If it stands up to scrutiny, it'll be added to the body of science on the topic and may do away with the need for dark energy in the models of the universe.

May.

Climate scientists are largely doing the opposite on the new AMOC study. Immediately after two successive years in which temps far exceeded predictions of the existing models, they're jumping to accept this one.

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XI_Vanquish_IX@reddit

Except when one uses a methodology that doesn’t project future conditions at all, it’s hard to compare them in any earnest

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Airilsai@reddit

This study doesn't include the key period where we approach and begin to tip over 1.5, 2018-2024, which is where we expect to observe AMOC collapse starting. Ending the data at 2017 and saying everything is okay is ridiculous.

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latepeaches@reddit (OP)

Submission statement: I have been following news about AMOC collapse for some time and was taken off guard by the publishing of this paper in the Nature journal. The paper suggests that sub polar gyre sea surface temperatures are not robust indicators of AMOC variability. What’s interesting about the paper’s approach is that it attempts to reconstruct the AMOC data by using these readings, and shows that it does not reflect the state of the AMOC.

I’m submitting this to the collapse subreddit because I’m not quite sure what to make of this paper. Is the AMOC shutting down or not? Fellow collapseniks who are more educated, please sound off!

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SaxManSteve@reddit

Basically the study is saying that recent papers on AMOC collapse modeled the integrity of AMOC by relying too much on SSTs as being an accurate proxy of AMOC stability. If instead you look at air-sea heat fluxes instead of SSTs then the data shows shows there's no weakening of the AMOC between 1963-2017. The author does clearly state that AMOC collapse is still a guarantee, but just that it's not gonna happen as soon as some recent papers have suggested.

Here's what the lead author posted on his Bluesky account.

Has the Atlantic Meridional Overturning Circulation (AMOC) weakened over the last decades? In our new study, we combine state-of-the-art CMIP6 models and observation-based estimates of the air-sea heat flux in the North Atlantic to show that the AMOC has not declined since the 1960s! 🌊

But did not changes in the sea surface temperature (SST) suggest a decline of the AMOC over the last decades?

In our study, we show that the anomalies in the AMOC and the SST in the subpolar gyre are not well correlated across CMIP6 models, suggesting that SSTs are not a reliable AMOC proxy.

Instead, past AMOC changes have mainly been linked to changes in the air-sea heat flux in the North Atlantic. If the AMOC strengthens, more heat is transported northward and released to the atmosphere. If the AMOC weakens, less heat is transported northward and heat is taken up from the atmosphere.

As expected based on this explanation, we found a tight relationship between anomalies of the AMOC and anomalies of the heat flux on decadal and centannial timescales across CMIP5 and CMIP6 models.

On annual timescales, other short-term processes strongly weaken the relationship.

We then combined this relationship with observation-based estimates of the air-sea heat flux to reconstruct the decadal-averaged AMOC since the 1960s.

Our reconstructions suggest that the AMOC has not declined yet!!!

Furthermore, the reconstructions do not show the simulated increase and decrease of the AMOC that is often seen in climate models and that is believed to be caused by aerosols.

Thus, the AMOC might be much less sensitive to external forcing on decadal timescales than previously believed.

As our approach relies on the integrated air-sea heat flux between the latitude of the reconstructed AMOC and the Arctic, the latitude can be changed. Thus, the AMOC can be reconstructed with air-sea heat fluxes at any latitude between 26.5°N and 50°N.

However, a so-far stable AMOC does not mean that the AMOC will not decline in the future. It is virtually certain that such a decline will happen, and its consequences will be dramatic. https://www.whoi.edu/oceanus/feature/whats-happening-with-the-amoc/

Although a decline is virtually certain, we do not know if a collapse is near. As AMOC reconstructions based on SST appear to be not robust, especially not on annual timescales, recent estimates of the time of the AMOC tipping based on SST-dervied AMOC strengths are likely not robust as well.

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StatementBot@reddit

The following submission statement was provided by /u/latepeaches:

Submission statement: I have been following news about AMOC collapse for some time and was taken off guard by the publishing of this paper in the Nature journal. The paper suggests that sub polar gyre sea surface temperatures are not robust indicators of AMOC variability. What’s interesting about the paper’s approach is that it attempts to reconstruct the AMOC data by using these readings, and shows that it does not reflect the state of the AMOC.

I’m submitting this to the collapse subreddit because I’m not quite sure what to make of this paper. Is the AMOC shutting down or not? Fellow collapseniks who are more educated, please sound off!

Please reply to OP's comment here: https://old.reddit.com/r/collapse/comments/1i3im08/new_amoc_study_critical_ocean_current_has_not/m7n2bw5/