Claim: Study pinpoints key causes of ocean circulation change

UNIVERSITY OF EXETER

Research News

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IMAGE: VARIABILITY IN OCEAN CURRENTS IS INFLUENCED BY MULTIPLE FACTORS. view more CREDIT: PROF HELEN JOHNSON

Researchers have identified the key factors that influence a vital pattern of ocean currents.

The Atlantic meridional overturning circulation (AMOC) carries warm water from the tropics northward.

Many scientists think that this heat transport makes areas including north-west Europe and the UK warmer than they would otherwise be.

Climate models suggest the AMOC is likely to weaken over the coming decades, with widespread implications for regional and global climate.

The new study – led by the universities of Exeter and Oxford, and published in Nature Geoscience – pinpoints the causes of monthly and annual AMOC variation and finds a differing picture at two key locations.

Observational data came from large arrays of monitoring equipment – off the coasts of Florida and Africa, and in the North Atlantic between Greenland and Scotland – run by the international RAPID and OSNAP projects.

“Understanding AMOC variability is challenging because the circulation is influenced by multiple factors that all vary and whose overlapping impacts persist for years,” said lead author Dr Yavor Kostov, of the Department of Geography at the University of Exeter.

“Our findings reveal the vital role of winds in driving changes in this ocean circulation.

“Winds were a key factor both in the sub-tropical and sub-polar locations we examined.

“As the climate continues to change, more efforts should be concentrated on monitoring those winds – especially in key regions on continental boundaries and the eastern coast of Greenland – and understanding what drives changes in them.”

While AMOC variability off the southern USA is dominated by the impact of winds, variability in the North Atlantic is generated by the combined effects of winds, heat and freshwater anomalies. “Our reconstruction suggests that, compared to the subtropics, the overturning circulation in the subpolar North Atlantic is more sensitive to changes in the background ocean state such as shifts in the sites of deep convection,” Dr Kostov said.

“This implies that future climate change may alter annual AMOC variability in this region. It emphasises the need for continued observations of the subpolar North Atlantic ocean.”

The study also finds that changes in the surface temperature and salinity near Canada and Greenland can trigger a delayed remote impact on the Atlantic circulation as far south as Florida.

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Funding for this study came from the UK Natural Environment Research Council, and the National Science Foundation, National Oceanic and Atmospheric Administration, NASA and Simons Foundation in the United States.

The paper, published in the journal Nature Geoscience, is entitled: “Distinct sources of interannual subtropical and subpolar Atlantic overturning variability.”

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dk_
June 2, 2021 2:13 am

Can you have it both ways? If AMOC weakens, then the continuing trend is for hurricanes to become less frequent and less powerful. Seems like a good thing.

Sebastian Magee
Reply to  dk_
June 2, 2021 2:54 am

Im not sure about that. Doesn’t a weaker AMOC imply less heat removal from the tropics towards the pole, thus a heating of the tropics and warmer for hurricanes to form?

dk_
Reply to  Sebastian Magee
June 2, 2021 3:25 am

Tropical warming causing North Atlantic cooling? Isn’t that still trying to have it both ways?

I thought Hurricanes have something to do with temperature differential off the North African coast. If the tropics are all warmer, does that mean fewer or more hurricanes?

Climate models suggest the AMOC is likely to weaken over the coming decades,

I saw somewhere recently that during the last ice age, the tropics were just as warm as today. Polar melt was supposed to be caused by more, warmer sea water. Stopping the North Atlantic “conveyor” was supposed, at one time, to trigger the next ice age. Increased glaciation was supposed to drop sea levels. Seems like weakening of AMOC solves everything, except maybe how to heat your house in Great Britain.

Last edited 3 months ago by dk_
Reply to  dk_
June 2, 2021 3:35 am

Increase in hurricane activity tells us the atmosphere is cooling.

Like when the earth is warming, most of the warming will happen at the poles, the temperature will be more uniform.
When it cools, temperature falls more at the poles. That means that the temperature difference between the poles and equator will increase, cold weather fronts from the poles meeting warm weather fronts from the temperate zones will more often be violent.

I.e. the complete opposite of what the “experts” are trying to make us believe.

Reply to  Roald J. Larsen
June 2, 2021 9:08 am

But recent data show that hurricanes show no trend in frequency or intensity over more than 100 years. An Inconvenient ( to the Warmists) Truth.

Reply to  john harmsworth
June 2, 2021 1:15 pm

I know, that’s what Tony Heller has been telling us, temperature is over all boringly stable, no trend, unless you use magnifying glasses of course …

Reply to  john harmsworth
June 2, 2021 6:53 pm

No upward trend.
That is even with the NHC naming brief whorls of wind tropical cyclones because their satellite algorithm states it is a tropical cyclone even if it does not meet the sustained winds time frame necessary to declare a tropical cyclone.

Nor does the NHC recognize the historic implications in such a long spell without major hurricanes hitting the USA regularly.
Instead, it is likely they’ll wax doomist when the majors return to hitting the North American coasts.

Duane
Reply to  dk_
June 2, 2021 7:10 am

Hurricane frequency and strength have nothing to do with CO2 or AGM, there is zero correlation. Hurricanes are an effect, not a cause, of changes in wind and ocean currents, dust, etc.

The principal effects on ocean currents occur only over geologic timescales, not the extremely short timescales these researchers are analyzing. Plate tectonics is the main driver of ocean currents, with the way that continents accrete or subdivide and move around on the earth’s surface, with a much lesser effect from glaciation in the polar regions.

dk_
Reply to  Duane
June 2, 2021 11:26 am

Study pinpoints key causes of ocean circulation change

They didn’t mention tectonic effects, nor CO2.

Agree completely that Hurricanes are an effect. Their claim was that “changes in wind and ocean currents” were what effected AMOC, too.

I don’t doubt or contest anything you’ve written here Duane, it just seemed to contradict this news release about conclusions from a new study, as well as other information offered about climate change and future hurricanes. Perhaps all predictions should be suspect?

Last edited 3 months ago by dk_
Duane
Reply to  dk_
June 3, 2021 5:06 am

This is an AGM blog, and posts like this are posted because they are relevant to longstanding arguments over AGM and CO2 regardless of whether the reported study directly blames that or not.

Never forget that one of the big scary ghost stories the warmists used to love to tell to frighten the kiddies (i.e., what they think of the average lay person – i.e., an immature moron or dolt easily frightened by ignorant claims), and which was made into at least one Hollywood blockbuster film that turned out to be a total flop at the box office, involved a sudden shift in ocean currents due to the affects of CO2-induced AGM. In effect, they created a self licking ice cream cone in which global warming causes global cooling. That way no matter what the weather does, it is the fault of CO2-induced global warming.

It’s like the old joke:

Question: “If a tree falls in a forest, and nobody was there to see or hear it fall, did it really fall?

Answer: “It doesn’t matter, it’s always the man’s fault”.

As asserted by feminists or wives and girlfriends … of course.

Or today, under the current administration of Bernie Biden and the DemoCommies, change the punch lie to:

“It doesn’t matter, it’s always the white man’s fault.”

June 2, 2021 3:21 am

The earth’s rotation is causing the ocean currents, the crust of the earth dictate where the water can go, if heat is driving convection in air, warmer water, regardless of reason, will only speed up ocean currents ..

But here’s the problem, these things doesn’t turn on a dime, the oceans are so vast, changes takes millenniums, guess that is the reason they need more money, sorry: more “research.”

Ron Long
June 2, 2021 3:35 am

So, “…the circulation is influenced by multiple factors that all vary…”. OK, how did the study isolate these multiple factors? They concluded that wind was important, so how did they isolate the effect of wind? One tenant of doing science is to control the variables so that the interacting systems can be studied one by one. This report is an admission that there is not sufficient data to deal with a chaotic and variable climate. Bad dog, no biscuit.

fretslider
June 2, 2021 3:57 am

Climate models suggest 

As the climate continues to change, more efforts should be concentrated on monitoring those winds – especially in key regions on continental boundaries and the eastern coast of Greenland – and understanding what drives changes in them.

It emphasises the need for continued observations of the subpolar North Atlantic ocean.

Fantastic they have some ideas and er, that’s it. Nothing really new. Postmodern pinpoint precision.

Climate models suggest what they’ve been programmed to.

Yooper
Reply to  fretslider
June 2, 2021 4:33 am

It emphasises the need for continued observations of the subpolar North Atlantic ocean.”

At least they say more OBSERVATIONS are needed, not more models based on nothing.

Eisenhower
Reply to  fretslider
June 2, 2021 3:48 pm

Bottom Line summary: We burned thru all our grant money to study wind in the atlantic ocean. We learned winds affect many things and further study is needed…something, something…Climate Change! When can we expect the next wheelbarrow of money?

mike macray
June 2, 2021 4:30 am

So maybe we are are living on a planet whose climate is controled/regulated by water after all?
Cheers
Mike

Joseph Zorzin
June 2, 2021 4:46 am

Off topic, sorry, but:

“The Biden administration suspended Trump-era Arctic drilling regulations to protect the Alaskan tundra, angering conservatives”
https://www.msn.com/en-us/news/politics/the-biden-administration-suspended-trump-era-arctic-drilling-regulations-to-protect-the-alaskan-tundra-angering-conservatives/ar-AAKCNId?ocid=Peregrine

“President Joe Biden’s administration has suspended Arctic drilling regulations imposed by President Donald Trump in an effort to protect the Alaskan tundra.”

There are millions of square miles of tundra, does it really need protecting?

saveenergy
Reply to  Joseph Zorzin
June 2, 2021 5:48 am

“There are millions of square miles of tundra, does it really need protecting?”

Yes,
so send all the green zealots to camp up there ( 1 zealot per square mile ) to protect it.
They can get all the power they need from their ultra-efficient renewables & live ‘close to nature’, any survivors can be picked up after 2 yrs.

rbabcock
Reply to  saveenergy
June 2, 2021 6:24 am

Fortunately there will be no polar bears as they are all dying off.

Clyde Spencer
Reply to  saveenergy
June 2, 2021 1:53 pm

Perhaps they could persuade those cuddly polar bears to run on super-sized hamster wheels to generate power to light their tents, cook their meals (no wood!), and recharge their smart phones.

Tom Abbott
Reply to  Joseph Zorzin
June 2, 2021 6:58 am

Biden is doing this to stop fossil fuel use.

As your gasoline prices continue to go higher, you know who to credit: Mr. Joe Biden and his delusional climate change mania.

If you set out to destroy the United States, you would do it just like Joe Biden and his lunatic Left are doing now.

Reply to  Tom Abbott
June 2, 2021 9:11 am

The result will be more Democrat wars over dependence on Middle Eastern oil.

Last edited 3 months ago by john harmsworth
Yooper
Reply to  Joseph Zorzin
June 2, 2021 7:08 am

It’s no more off topic than this gem, talk about extravagant speculation:

https://summit.news/2021/06/01/japanese-researchers-use-soybean-compound-to-turn-male-fish-female/

D Boss
June 2, 2021 5:40 am

So let me get this straight…. they indicate the following:

“Our findings reveal the vital role of winds in driving changes in this ocean circulation.”

And the Climate Cult demands we erect tens, perhaps hundreds of thousands of windmills to generate electricity to replace fossil fuels…

And the laws of physics say unequivocally that if you extract mechanical energy from the wind, that wind has lower energy, via [wind] speed reduction….

So are we not potentially drastically altering the climate by these asinine wind turbines either already erected or proposed?

The lunacy of Climate Cult propositions such as massive wind farms to solve an imagined problem, is like giving a troupe of baboons a case of loaded and cocked AK-47’s. Nothing good will come of this!

Dave Fair
Reply to  D Boss
June 2, 2021 1:33 pm

In this case the AKs are UN IPCC CliSciFi models and the baboons are the willfully ignorant ‘scientists.’

Eisenhower
Reply to  D Boss
June 2, 2021 3:51 pm

Translation: We need the govenment to send more money. We’d even accept money from a windmill company.

taxed
June 2, 2021 6:43 am

With wind been such a key factor in ocean currents, it help’s to explain how the global climate cooled during the LIA. Because its looking like when the smooth flow of the global jet stream brakes down. One of the impacts it has it that it also help’s to brake down the smooth flow of the global wind patterns. Leading to more changes in wind direction over the global surface.
This more messy global wind patterning in turn makes it harder for the ocean currents to flow smoothly.

Tom Abbott
June 2, 2021 6:53 am

From the article: ““As the climate continues to change”

Oh, brother!

Human-caused Climate Change is pure speculation. Assuming it exists and is happening now, demonstrates a lack of understanding of the situation.

Tom Abbott
June 2, 2021 7:03 am

I believe there was an article not too long ago claiming the winds, not the AMOC, were the major reason for why the UK had such a warm climate.

garboard
June 2, 2021 9:33 am

I think until and unless you have lived in the tropics where the trade winds blow Every Day from the east and quite strongly most of the year you can’t really imagine the effect of wind on the ocean . if there were no continental land the ocean would mostly just continuously flow west below 30′ from the equator , notwithstanding a little nudge from the coriolis . sea level height off Africa in the N Atlantic is something like a foot or two less than when it gets to Central America.

June 2, 2021 1:21 pm

One feature of alarmist climate science is a focus on the atmosphere only while ignoring the ocean. Climate change can only be driven from the atmosphere via CO2 or volcanoes. According to this narrative, the ocean plays no independent role, it just obediently follows the atmosphere. 3% of climate energy in the atmosphere controls 97% of climate energy in the ocean.

This paper is no exception. It’s main finding? “What controls ocean currents? Wind!”. True to form.

Mutual causation is not comprehensible in this narrative, but it’s the reality in the atmosphere-ocean where causation goes both ways. Winds over the ocean are driven by gradients in sea surface temperature (SST). Cold SST cools air to higher density, and winds flow from regions of cold to warmer SST. That’s how cold upwelling off Peru drives the easterly Pacific trade winds. The trade winds entrain further upwelling which in turn strengthens the trade winds. This is the Bjerknes feedback that is a key part of the ENSO.

But such mutual ocean-atmosphere coupling is universal. In the Atlantic, the Gulf Stream carries warm high-salinity water to the ocean’s north-east corner. This warming of the seas off Scotland and Norway impels westerly winds from the colder central and western North Atlantic. The westerly winds will tend to strengthen the Gulf Stream itself. This is the feedback central to the oscillation in strength of the Atlantic Meridional Overturning Circulation (AMOC) from which emerges the Atlantic Multidecadal Oscillation (AMO). These chaotic oscillatory dynamics are driven by atmosphere-ocean mutual forcings yielding emergent spatiotemporal pattern.

Runs of AMOC self-reinforcement are terminated when Arctic melt from the warming chokes off the salinity driven cold water downwelling in the Norwegian Sea. Then the AMOC and Gulf Stream start to weaken and the north east Atlantic cools. That’s where we are now in the cycle.

Winds are driven by temperature and density gradients caused by SST patterns. The winds in turn impel the ocean currents. Feedbacks as is well known in chemical engineering reduce the dimensionality of chaotic turbulence in fluid flow systems pushing the system toward the borderline low dimensional chaos region where emergent pattern occurs. Emergent pattern on many time and spatial scales plays the thermodynamic role of exporting entropy. To keep the editors happy.

https://ptolemy2.wordpress.com/2020/07/26/from-chaos-to-pattern-in-ocean-driven-climate/

John I Reistroffer
Reply to  Hatter Eggburn
June 2, 2021 4:19 pm

“This implies that future climate change may alter annual AMOC variability in this region. It emphasises the need for continued observations of the subpolar North Atlantic ocean.”

From my point of view, it looks like the above statement by the authors is back-assward.
I would suggest that the AMOC variability in this region would affect the climate, rather than the climate affecting the AMOC.

Reply to  John I Reistroffer
June 3, 2021 8:33 am

Yes that a shorter way of saying it

Reply to  Hatter Eggburn
June 2, 2021 10:43 pm

Auditors, not editors.

Rainer Bensch
June 3, 2021 3:38 am

“As the climate continues to change, more efforts should be concentrated on monitoring those winds – especially in key regions on continental boundaries and the eastern coast of Greenland – and understanding what drives changes in them.”

Well, as the climate continues to change, less or more butterflies will be flapping their wings.

Ulric Lyons
June 3, 2021 11:33 am

Easier to look at the resultant AMO anomalies, which are cooler when the solar wind is stronger, via positive NAO/AO, and warmer when the solar wind is weaker, via negative NAO/AO.

Rising CO2 forcing is expected to increase positive NAO/AO conditions, so in theory it should inhibit AMO warming, and exacerbate AMO cooling.

https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-5-6.html

Tom Johnson
June 3, 2021 6:35 pm

Water at the equator is travelling along with the earth at over a thousand miles an hour. But for a bit of convection, it’s stationary. So, in travelling from the equator to the north pole, where does all that momentum go? It seems to me that in discussing ocean currents, this Coriolis Effect would be mentioned.

beng135
June 4, 2021 5:35 am

Rent/grant-seeking.

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