Are the North Atlantic Currents Strengthening or Weakening?

Art Viterito

One of the most important questions in the geophysical sciences is whether the system of currents of the North Atlantic, collectively referred to as the Atlantic Meridional Overturning Circulation, or AMOC, has strengthened or weakened in recent years.

Opinions vary widely, but there’s a strong consensus among climate modelers that the AMOC has weakened in the past and will continue to weaken going forward. A slowing AMOC could have profound impacts on the global climate, ranging from cooling in Northern Europe and the Arctic to accelerated trade winds in the Pacific.

CURRENTS AND CIRCULATION – Scotland’s Marine Atlas: Information for The National Marine Plan – gov.scot (www.gov.scot)

By contrast, recent empirical studies have challenged the “weakening” hypothesis. Getting the argument “right” is critically important, as a strengthened AMOC would increase Arctic temperatures. This would result in diminished ice cover in the Arctic Ocean, permafrost retreat, expansion of the boreal forests, and shrinkage of the Eurasian and North American tundra. Three recent studies clearly illustrate this critical epistemological divide.

In a 2018 modeling study by Caesar, et al., (Observed fingerprint of a weakening Atlantic Ocean overturning circulation | Nature), the authors conclude that the AMOC has been weakening since the mid-twentieth century. To quote directly from the study:

“This weakening is revealed by a characteristic spatial and seasonal sea-surface temperature ‘fingerprint’—consisting of a pattern of cooling in the subpolar Atlantic Ocean and warming in the Gulf Stream region—and is calibrated through an ensemble of model simulations from the CMIP5 project. We find this fingerprint both in a high-resolution climate model in response to increasing atmospheric carbon dioxide concentrations, and in the temperature trends observed since the late nineteenth century. The pattern can be explained by a slowdown in the AMOC and reduced northward heat transport….”

By contrast, a 2021 empirical study by Oziel, et al. (Faster Atlantic currents drive poleward expansion of temperate phytoplankton in the Arctic Ocean | Nature Communications) largely contradicts this finding. In their research of North Atlantic currents, the authors demonstrate that the Northern Branch of the Gulf Stream has increased in speed by as much as a factor of two since 1995. Using phytoplankton and satellite data, they conclude: 

“The Arctic marine biome, shrinking with increasing temperature and receding sea-ice cover, is tightly connected to lower latitudes through the North Atlantic. By flowing northward through the European Arctic Corridor (the main Arctic gateway where 80% of in- and outflow takes place), the North Atlantic Waters transport most of the ocean heat, but also nutrients and planktonic organisms toward the Arctic Ocean. Using satellite-derived altimetry observations, we reveal an increase, up to two-fold, in North Atlantic current surface velocities over the last 24 years.”

A third study, which combines modeled results with a wide array of empirical inputs, corroborates the Oziel et al. findings. As the authors state in Nordic Seas Heat Loss, Atlantic Inflow, and Arctic Sea Ice Cover Over the Last Century – Smedsrud – 2022 – Reviews of Geophysics – Wiley Online Library:

“The Arctic Ocean, including the Nordic and Barents Seas, has warmed since the 1970s. This warming is congruent with increased ocean heat transport and sea ice loss and has contributed to the retreat of marine-terminating glaciers on Greenland.”

A press release of this study by the Bjerknes Center for Climate Research (The Gulf Stream has increased steadily over the last century (uib.no)) states:

“The heat transport into the Nordic Seas has increased steadily in volume and temperature over the last century…”

The Bjerknes press release goes on to say:

“It was surprising to find such consistent results that show a steady increase, which entails that the Gulf Stream’s extension into the Nordic Seas has strengthened…. With the surprising volume increase, the total heat transport has increased … 30 percent.”

Of note in these remarks is that the researchers (there were 17 on the team) were “surprised” by the strengthening. Undoubtedly, this is a reaction to the large number of modeling studies that have concluded otherwise. Clearly, climate science has become deeply committed to numerical modeling with diminishing regard for empirical inputs.

Rooted in the long-standing traditions of the scientific method, we should never ignore the value of observation. Furthermore, we must stop being so reliant on “tuned” algorithmic constructs of our world, as their products have been used to craft far-reaching policies affecting how we value and use our resources. Empiricism should always be the touchstone of climate inquiry. The modelers may think differently on this, but the temperate-loving phytoplankton that have recently migrated to the Arctic would surely beg to differ.

4.8 30 votes
Article Rating
44 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
Scissor
September 11, 2022 2:02 pm

Yes.

Richard Brown
September 11, 2022 2:09 pm

The AMOC is rarely mentioned these days unless it is by real scientists!
Although the AMOC is a known driver of changes to climates, media either ignore it or don’t know about it.
It’s like the great pacific climate shift of 1976/77….rarely mentioned.

Tom Halla
September 11, 2022 2:15 pm

Another beautiful theory, killed by an ugly little fact?

BrianB
Reply to  Tom Halla
September 12, 2022 6:09 am

Of course not. Evidence that is 180 degrees opposite of their theory does not invalidate it. It confirms it but does demonstrate they were far too open minded and tolerant of conflicting data previously, something they will be sure to guard against with even more vigilance going forward. Until it happens again.
Welcome to climate science.

son of mulder
September 11, 2022 2:30 pm

How is it affected by the warm current coming from the Indian Ocean towards tha pointy bit of Brazil. Slightly north and much warm water enters the North Atlantic, a bit further south and it gets forced down towards Antarctic waters. Which models is that in?

Chris Hanley
September 11, 2022 2:44 pm

Rooted in the long-standing traditions of the scientific method, we should never ignore the value of observation

That is so fundamental that it is puzzling that it needs to be said.
100 years of data recorded directly accurately and objectively would be hardly enough to derive any understanding of complex climate systems.
After all from Aristarchus to Copernicus took merely eighteen centuries of detailed observations.

Jeff Alberts
Reply to  Chris Hanley
September 11, 2022 4:45 pm

After all from Aristarchus to Copernicus took merely eighteen centuries of detailed observations.”

Hah! Punters! They didn’t have Xbox!

Rud Istvan
September 11, 2022 3:03 pm

The AMOC climate question highlighted by this post is so important that the RAPID moored buoy system was installed in 2004 precisely to observe AMOC, actually a system of several separate known currents including the Gulf Stream.

RAPID is a string of ocean floor moored buoys at 26.5N latitude stretching completely across the Atlantic from Florida to Africa. It measures at various depths temperature, conductivity (salinity), pressure, current speed and direction. The data are sent from the surface buoys via Iridium satellite to both the US and UK. A good basic overview is at rapid.ac.uk. The data is also integrated with any ARGO floats in the vicinity of the RAPID string—provides QC and additional ‘continuous’ depth info.

The data only spans about 20 years so far. It shows some previously unknown decadal AMOC variation, but NO general trend either positive or negative (as predicted by climate models).

commieBob
Reply to  Rud Istvan
September 11, 2022 3:21 pm

All true, and yet this 2020 paper (which I also link below) shows how messy things can get. Even if folks purported to find a trend, I’d be skeptical.

Chris Hanley
Reply to  Rud Istvan
September 11, 2022 6:22 pm

Reading this a layperson might be forgiven for concluding that the only purpose of observations was to verify the models.

Last edited 2 months ago by Chris Hanley
commieBob
September 11, 2022 3:10 pm

I always thought there were many many current gauges in the North Atlantic. Apparently I was wrong.

I also never considered that the current might be seasonal. Wrong again.

Things are complicated enough that a bad actor, like the self-admitted* fraud Dr. Mann, could muster data to prove anything necessary to bolster any chosen theory.

*If you sue someone for defamation, and then you avoid going to court and presenting evidence under your control, that opens you to adverse inference. Because of his inexcusable delays in his lawsuit against Dr. Ball, Mann has done just that.

jeffery P
September 11, 2022 3:12 pm

What the hell is a modeled study? Seriously, this is science?

Rud Istvan
Reply to  jeffery P
September 11, 2022 4:39 pm

You missed the all important modifier, ‘climate’ science. In ‘climate science’, models produce data.

KcTaza
Reply to  Rud Istvan
September 11, 2022 5:14 pm

Indeed and inconvenient facts or unknowns are not even mentioned.

“Climate model projections are fantasies that climatologists wish they could prove are happening in the real world. They’re climate porn.”

Ability of mankind to solve problems is beyond imagination
https://bit.ly/3aXcB5z
7/21/22

Excerpt:
A: I have three principal recommendations:
1. Today’s government policies are driven by computer models. However, the results of those models are completely determined by what the modelmakers put into them. Modelmakers can set up a model in such a way that it produces whatever the financier wants to see. Politicians are fond of models. In governmental research institutes, scientists follow instructions to set up ‘scientific’ models in such a way that the outcome favors the intended governmental policy. They then blatantly claim that the outcome is scientifically sound. My advice is to ban the use of politics-driven ‘scientific’ models all together. Those false models push us back into the dark times of superstition.

Gen Lee Schtiff
Reply to  KcTaza
September 12, 2022 1:04 am

Quatum computers… AI… Predictable Future(s).

Trying to Play Nice
Reply to  KcTaza
September 12, 2022 7:18 am

It works that way in industry also. My company brought in modelers to show how a new process would work but the inputs were what management wanted the machines to do, not what they really could do. The result was that management was always unhappy with the real world.

Zig Zag Wanderer
Reply to  jeffery P
September 11, 2022 6:27 pm

Seriously, this is science?

No, Scientology.

Phil.
Reply to  jeffery P
September 13, 2022 11:11 am

It actually says “modeling study”. However, yes this is science, it’s what’s known as the ‘scientific method’, you develop a hypothesis (model), conduct experiments to test it, if they don’t support it you revise your hypothesis and try again. Like the ‘ideal gas law’ it works under some conditions but under others it doesn’t and has to be modified (Van der Waals equation).

Bob
September 11, 2022 3:16 pm

I understand there is a place for models. I understand that models can be very helpful. The evil climate scientists(?) have abused models and given them a bad name. We can make assumptions and include them in the model, if the model results match observations we can feel stronger about our assumptions. Models don’t tell us we are right or wrong, they tell us how close our thinking is to observations. The green devils are telling us that the models rule and if observations don’t match the models then our measuring ability hasn’t kept pace with the models. That is exactly backwards, that is why I pay no heed to models, which is a sad state of affairs.

Michael ElliottMichael Elliott
Reply to  Bob
September 11, 2022 3:37 pm

When the first mention of CO2 was made, I lost interest.

The idea that tiny CO2 could affect the movement of warm water from the Gulf of Mexico is laughable.

Especially as it’s effect is swamped by the massive ” Greenhouse effect” of water vapour, is as said, its laughable.

As always its back to the Sun. The Atmosphere is influenced by the vast Oceans, not the other way around.

It’s the Suns “Weather” we should be studying, not Models.

They are based on Hyposuses, which is just a fancy word for a guess.

It may well be a best guess, but it’s still just a guess.

Michael VK5ELL

RickWill
Reply to  Michael ElliottMichael Elliott
September 11, 2022 4:39 pm

Climate models are based on the entirely primitive belief that clouds are FIXED; that the sun is FIXED and Earth’s orbit is FIXED. The only thing changing is CO2 so every weather trend is related to CO2.

If the crazies are ever able to get the surface covered with wind turbines and solar panels they will begin to realise that there is more than CO2 at play. They will manage to convert large regions of productive land to deserts.

RickWill
September 11, 2022 4:26 pm

The idea that climate models produce anything of value is ridiculous. They are models directed at demonising CO2 – nothing more, nothing less. Unrelated to anything that occurs in Earth’s climate system. But it is another snippet demonstrating their ineptness.

On the hand this caught my eye.

One of the most important questions in the geophysical sciences is whether the system of currents of the North Atlantic, 

Really – MOST IMPORTANT – to whom?

Gen Lee Schtiff
Reply to  RickWill
September 12, 2022 1:07 am

Demonizing CO2 = Demonizing Humans

Jeff Alberts
September 11, 2022 4:43 pm

All of climate science is about detecting (or imagining or faking the detection of) small perturbations in the climate system, and declaring an emergency. Never mind that these perturbations have always happened (often in much larger ranges) and always will happen. This is worse than Chicken Little and Crying Wolf.

Michael E McHenry
September 11, 2022 4:48 pm

Models say its weaking and observation says strengthening hmmm sound familiar?

KcTaza
September 11, 2022 5:05 pm

“A slowing AMOC could have profound impacts on the global climate, ranging from cooling in Northern Europe and the Arctic to accelerated trade winds in the Pacific.”

My first thought was that, finally, they admit there is more to climate than CO2. My hopes were quickly dashed when I read farther.

“We find this fingerprint both in a high-resolution climate model in response to increasing atmospheric carbon dioxide concentrations, and in the temperature trends observed since the late nineteenth century. The pattern can be explained by a slowdown in the AMOC and reduced northward heat transport….”

Good grief, did any of their models explain how and why AMOC changed many times in the past without high CO2 or, why it started warming in the late 19th century when fossil fuels were not widely in use?

Redge
Reply to  KcTaza
September 11, 2022 11:38 pm

And which came first, the chicken or the egg?

Gen Lee Schtiff
Reply to  Redge
September 12, 2022 1:10 am

A Christian would say the chicken, Darwinism the egg.

Rud Istvan
Reply to  Redge
September 12, 2022 11:57 am

A chicken is an egg’s way of making another egg.

KcTaza
September 11, 2022 5:23 pm

Climate scientists (if such a discipline can even be said to exist) do not understand clouds nor how they effect Earth’s climate. However, since they haven’t figured out a way to model clouds, they don’t exist, or are ignored.
This is insane.
Some excellent observations from real scientists.

Ability of mankind to solve problems is beyond imagination
https://bit.ly/3aXcB5z
7/21/22
A: I have three principal recommendations:
1. Today’s government policies are driven by computer models. However, the results of those models are completely determined by what the modelmakers put into them. Modelmakers can set up a model in such a way that it produces whatever the financier wants to see. Politicians are fond of models. In governmental research institutes, scientists follow instructions to set up ‘scientific’ models in such a way that the outcome favors the intended governmental policy. They then blatantly claim that the outcome is scientifically sound. My advice is to ban the use of politics-driven ‘scientific’ models all together. Those false models push us back into the dark times of superstition.

46 STATEMENTS By IPCC Experts Against The IPCC
https://bit.ly/36ZEesl
3/7/20

7. Dr Robert Davis: “Global temperatures have not been changing as state of the art climate models predicted they would. Not a single mention of satellite temperature observations appears in the IPCC Summary for Policymakers.”

9. Dr Chris de Freitas: “Government decision-makers should have heard by now that the basis for the long-standing claim that carbon dioxide is a major driver of global climate is being questioned; along with it the hitherto assumed need for costly measures to restrict carbon dioxide emissions. If they have not heard, it is because of the din of global warming hysteria that relies on the logical fallacy of ‘argument from ignorance’ and predictions of computer models.”

JBP
September 11, 2022 6:42 pm

but if Dr. Javier ??’s and Andy May’s work on the Meridional Transport holds water, then the supposition in this article about the result (AMOC weakening = cooler, strengthening = warmer) is bass akwards, isn’t it?

Doesn’t MT increase with strengthened AMOC, in turn increasing the LTG, and consequently raises the amount of heat to the pole, and subsequently increasing the heat leaving Gaia, and we all cool off……

rbabcock
September 11, 2022 7:14 pm

The Beaufort Gyre is overdue to do what it does to the AMOC. I have a feeling the volcanoes, the Beaufort Gyre and a few other big climate influencing events are all going to go off at the same time and we all need to be ready. But we will not be.

Karl of Lochalsh
September 11, 2022 8:55 pm

So as usual it’s all models; no sign of real science, just guessing, might, and maybe. When the AMOC flow is increasing well that’s just inconvenient. Nothing to see here, please move along.

Julian Flood
September 11, 2022 10:38 pm

I have an interesting observation.

From a point about fifty miles west of southern Portugal, draw a line to about 200 miles (maybe a bit less) short of Madeira. In early 2012 a fractured smooth at least one hundred miles wide with very little cloud cover was sitting over an area of tens of thousands of square miles.

Surface winds of about Force 4 induced wave breaking in the unsmoothed areas while the smoothed areas resisted.

What caused that smooth? Thin oil/surfactant films supposedly oxidise too quickly for anthropogenic oil pollution to be the cause. The area had sat under an Azores high pressure area for a couple of weeks and was largely cloud free. .

That’s the observation. My guess is that the explanation will tie in with the Evans and Ruf paper which tried to examine surface microplastic pollution in the North Atlantic gyre but which found different and more interesting data.

Now another interesting observation. Why is no-one interested?

JF
If I had to bet I’d go for polluted run-off from farming, sewage, dissolved silica induced boom and bust in oleaginous phytoplankton but I would naively have expected the simple observation itself to be interesting to climate science.

Rod Evans
Reply to  Julian Flood
September 11, 2022 11:51 pm

I am always eager to understand unusual observations and concerns. Sadly I don’t know what a ‘fractured smooth’ is? I imagine it to be some pet term used by a group of scientists in a detailed study/discipline, unfortunately it is outside my standard Engineering studies.

Lit
September 12, 2022 1:15 am

The same thing happened in early 1900´s when Arctic had a massive melting. It´s very simple, ice melts when there´s a stronger warm current going further north. The stronger the current is, more melting will happen. The idea that less ice in the Arctic would coincide with weaker current is crazy. Cause and effect is obvious here.

Bruce Cobb
September 12, 2022 4:34 am

If they are strengthening it’s due to “climate change”, and if they are weakening it’s also due to “climate change”. Heads they win, tails we lose.

Duane
September 12, 2022 5:22 am

The timeframes over which any changes are either modeled or actually detected are so short – just a few decades – that whatever changes may be underway, if any, are simply cyclic changes, not representative of long term climate change. The basic “design” of AMOC was set with the tectonic movement of plates on the earth’s crust, including the closing of the gap between the American continents at the isthmus of Panama.

Yooper
September 12, 2022 5:25 am

How come no one has presented a cause for/of the changes in the AMOC? Observing something that one didn’t expect should lead to asking “Why”.

September 12, 2022 7:02 am

Please be informed, that there is a paper in 2022 that contradicts Caesar et (2018). full: https://dro.dur.ac.uk/35682/1/35682.pdf?DDD14+djlm41+vbdv77 They found, that the paper with the finding of a strongly reduced AMOC in current years was some kind of flawed due to the selecetion of proxies. IMO the impact of Caesar (2018) was overstimated. Care has to be taken when a study comes from the Potsdam institute for climate impact research or as they say in climate science: “crazy Germans”.

hunterson7
September 12, 2022 8:04 am

Benjamin Franlin documented the variable nature of the Gulf Stream. Climate crooks lie aboutvthis variability to scare people and feed money to the climate hype industry.

DMacKenzie
September 12, 2022 9:42 am

The North Atlantic current will slow down when the planet quits rotating on its axis.

Robert Wager
September 13, 2022 12:37 pm

How about the AMO? It is my understanding the shift is going colder in the coming decades. Am I right?

Garboard
September 14, 2022 7:36 am

When it comes to long term collection of empirical data on Gulf Stream velocity , no one comes close to Tom Rossby , who thinks talk of Gulf Stream slowdown is junk science

%d bloggers like this: