WOODS HOLE OCEANOGRAPHIC INSTITUTION
A key component of the Gulf Stream has markedly slowed over the past century–that’s the conclusion of a new research paper in Nature Communications published on August 7. The study develops a method of tracking the strength of near-shore ocean currents using measurements made at the coast, offering the potential to reduce one of the biggest uncertainties related to observations of climate change over the past century.
“In the ocean, almost everything is connected,” said Christopher Piecuch, an assistant scientist in the Physical Oceanography Department at the Woods Hole Oceanographic Institution (WHOI) and author of the study. “We can use those connections to look at things in the past or far from shore, giving us a more complete view of the ocean and how it changes across space and time.”
Piecuch, who specializes in coastal and regional sea level change, used a connection between coastal sea level and the strength of near-shore currents to trace the evolution of the Florida Current, which forms the beginning of the Gulf Stream. The Gulf Stream flows north along the Southeast Atlantic Coast of the United States and eventually east into the North Atlantic Ocean, carrying heat, salt, momentum, and other properties that influence Earth’s climate. Because nearly continuous records of sea level stretch back more than a century along Florida’s Atlantic Coast and in some parts of the Caribbean, he was able to use mathematical models and simple physics to extend the reach of direct measurements of the Gulf Stream to conclude that it has weakened steadily and is weaker now than at any other point in the past 110 years.
One of the biggest uncertainties in climate models is the behavior of ocean currents either leading to or responding to changes in Earth’s climate. Of these, one of the most important is the Atlantic Meridional Overturning Circulation, or AMOC, which is a large system or “conveyor belt” of ocean currents in the Atlantic that includes the Gulf Stream and that helps regulate global climate. Piecuch’s analysis agrees with relationships seen in models between the deeper branches of the AMOC and the Gulf Stream, and it corroborates studies suggesting that the deeper branches of AMOC have slowed in recent years. His method also offers the potential to monitor ocean currents like the Gulf Stream from the coast, complementing existing but difficult-to-maintain moored instruments and expensive research cruises.
“If we can monitor something over the horizon by making measurements from shore, then that’s a win for science and potentially for society,” said Piecuch.
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The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit http://www.whoi.edu.
Key Takeaways
The Florida Current, which forms the start of the Gulf Stream, has slowed over the past century and is the slowest it has been at any point in the past 110 years.
Historical analysis of the current was made using sea level records from Florida and the Caribbean.
Slowing of the Florida Current relates to the strength of the Gulf Stream and the much broader system of currents known as the Atlantic Meridional Overturning Circulation (AMOC) that helps regulate global climate.
Understanding past changes in ocean currents helps reduce one of the biggest uncertainties in observations of climate change over the past century.
1) I’d love to see more on how they connect sea levels on shore with the speed of this current, excluding everything else that can impact sea levels.
2) Have they adjusted sea level for changes in land level?
3) Why do they assume that the changes in the current are unique and haven’t happened before?
The full article is posted, see for yourself. https://www.nature.com/articles/s41467-020-17761-w
Don’t need to look too far. From the abstract:
“These data are too short for assessing possible multidecadal or centennial trends. Here I reconstruct Florida Current transport during 1909–2018 using probabilistic methods and principles of ocean physics applied to the available transport data and longer coastal sea-level records.”
Possible trends with what level of possibility?
Probabilistic reconstruction = sophisticated guessing
Interesting paper but certainly not proven truth. It’s science after all.
“Interesting paper but certainly not proven truth. It’s science after all.”
math and logic give you proof.
science is contingent, no proofs, only highly probable findings.
more likely or less likely
https://www.youtube.com/watch?v=wLaRXYai19A
math an logic give you a picture or estimate of the reconstruction.
In other words, barring mistakes it gives you a somewhat better guess as to what is going on. Probabilistic methods will give a different answer every time it is run.
It may take a very long time rolling 6 dice to get a repeat sequence.
Interesting theory there; now prove the model and prove the math, prove that it has a relationship to the Gulf Stream.
Given the extraordinary claim regarding the Gulf Stream is weakening, proving that requires extraordinary evidence.
How about the last five thousand years or maybe the last ten thousand years. With a life span of about 82 years we need to shut up and live our lives.
Given the direction the Central Authoritarians want to take us and the horrific degradation in the quality of life they envision for those of us not part of the politburo, 82 years would seem like eternity. but they will do their best to shorten that significantly for the masses. Hopefully those in control will keep Vodka cheap so the misery can be endured until our livers give out.
Not to mention apparent sea level changes caused by overhead low and high pressure systems and offshore and onshore winds.
Of course it’s never happened before! It would be too inconvenient if it had! It would dare wash away the narrative.
This would be more interesting if Woods Hole (and Scripps) did not have a shameful history of promoting the AGW myth.
Promoting “everything’s great” has no benefit for them.
When oceanographers or climate “scientists” use
statistics or math or “simple physics,” watch out.
Did they say that the 110 year historical trend was caused by CAGW? True, false, or just interesting conjecture, I don’t see how that affects the CAGW “debate.”
BTW, could the world’s coming out of the LIA have been part of the cause of the slowing of the current (if it’s real)?
I have a grade 12 education, plus over 50 years experience in the work place. my nose is picking up the pungent aroma of bull droppings. Sorry, way too many assumptions had to have gone into this and what did they produce, GIGO.
A few sonobouys dropped in various areas, tracked and recorded then charted would give near real time information, that compared to historical LONG term records that would be irrefutable. This piece of work is (to me) very refutable.
The assumptions must be right. They reached the correct conclusions.
well said!
What? . . . an article without reference to CO2-induced global warming? How refreshing.
They should have actual readings of current velocity for at least the last 90 years. How does the model compare ? What are the numbers ? How big are the error bars ? How much slower is it now than a century ago ? The article is pretty lacking in the scientific journalism department.
“The Florida Current, which forms the start of the Gulf Stream”
This must be a journalist’s interpretation?
If the Florida current (Gulf stream) is weaker by any significance, would not western Europe cool some? Inquiring minds want to know.
MarkW’s comment is spot on relative to seal level rise from gages. However, there is another factor that explains most of the cause for an actual current speed drop. It has been observed that whatever the cause, if global temperature rises, most of the increase is at higher latitudes (2 to 3 times that near the tropics). The temperature difference between lower and higher latitudes is the driving force (cause of surface wind speed) for the near surface current, and thus the AMOC. The temperature rise from the recovery from the little ice age plus any small human contribution is thus a likely reason for a slowdown, and this would level off if the temperature flattened, and current would speed up if the temperature dropped.
Less ice in the arctic should cause more evaporation and more heat loss to arctic waters. This would cause the rate at which water sinks in the arctic to increase. This should serve to accelerate the gulf stream.
MarkW, the wind driving the currents is the main factor. With lower wind (from less temperature difference with latitude), the arrival of replacement water for the sinking water (from evaporation and radiation cooling) is slower, and this prevents a speed up of the loop, and actually results in slowing of the process.
Hello Leonard. There is one very long record of winds speed which might be informative: The Great Blue Hill weather station about 15 miles south of Boston. The location of this station (about 650 Ft elevation, I think), gives a good sampling of wind speed without too many local influences. This page shows graphs of all the weather records since the late 1800’s: https://bluehill.org/observatory/2014/02/graphs-of-annual-blue-hill-observatory-climate-data/
The graph that caught my attention was the drop in average wind speed since about 1980. Since the prevailing westerlies at the latitude of the station are part od what drives the Gulf Stream. The drop is in wind speed is consistent with a drop in Gulf Stream speed.
The temperature has gone just about 2 degrees F since 1980, or about 1.1 degrees C. That’s around 0.27 degrees C per decade since 1980. Not that far off from Spencer’s satellite data. If there is some heat island effect, they’d probably be very close.
The weather station is ~650 feet up on top of a very steep hill, with relatively flat surrounding terrain, and nowhere near the city. It is surrounded mostly by forested area and a pond (Houghton’s pond). I doubt there is much heat island effect.
“…use mathematical models and simple physics…”
He still doesn’t get it, does he.
“One of the biggest uncertainties”…”use mathematical models and simple physics…”
..if it was so damn simple…he wouldn’t be the first to do it
“In the ocean, almost everything is connected. We can use those connections to look at things in the past or far from shore, giving us a more complete view of the ocean and how it changes across space and time.”
Except it is not mathematically sound – we would need a complete snapshot of the present. As it is, the best we can do is to play a time-reversed video of homogenized data. Make no mistake, homogenized data can look very real.
” The data are modeled as corrupt, imperfect versions of the processes. Bayes’ rule is used to invert the model equations, and solutions are generated using numerical methods. The model equations are coupled, so that information is shared across space, time, and processes, which allows data gaps to be filled and unobserved processes to be estimated. The solution is fully probabilistic, and comprises thousands of ensemble members, each an equally likely history of transport that is consistent with the data and model equations.” Yup, Just as I suspected, someone playing with a computer model and fiddling with parameters. Garbage in garbage out.
“. . . allows . . . unobserved processes to be estimated . . .” THAT is all one needs to know to ascertain the scientific validity of this study and its key takeaways.
My key takeaway is the one at the end of the road!
Better than the authors?
I think so.
Auto
But how much is “weaker”? Is it a 1%, 10%, 50%? Is it referred to what, water flow, water temperature (i.e. net transport of energy)? How does it effect the whole atmspheric and oceanic surface system of the North Atlantic? It is really not clear nor precise.
From the above article: “Piecuch, who specializes in coastal and regional sea level change, used a connection between coastal sea level and the strength of near-shore currents to trace the evolution of the Florida Current, which forms the beginning of the Gulf Stream.”
Well, that’s fine as far as it goes, but what about the strength of far-from-shore and/or deeper currents in the Gulf Stream? Might they have correspondingly increased, thereby offsetting the weakening of near-shore Gulf Stream currents?
“The Gulf Stream is typically 100 kilometres (62 mi) wide and 800 metres (2,600 ft) to 1,200 metres (3,900 ft) deep. The current velocity is fastest near the surface, with the maximum speed typically about 2.5 metres per second (5.6 mph).”— https://en.wikipedia.org/wiki/Gulf_Stream#cite_note-25
Note the weasle-wording in the above article regarding this big picture consideration (my added capitalization for emphasis):
“. . . it corroborates studies SUGGESTING that the deeper branches of AMOC have slowed in recent years. His method also offers the POTENTIAL to monitor ocean currents like the Gulf Stream from the coast, complementing existing but difficult-to-maintain moored instruments and expensive research cruises.
. . . ‘IF we can monitor something over the horizon by making measurements from shore, then that’s a win for science and potentially for society,’ said Piecuch.”
Bottom line: the above article’s title is not supported objectively by the information provided, all things considered.
If that really were so why hasn’t the north of Norway frozen over? Why is there not much more ice in the Barents Sea? Why is there open water at Murmansk and Archangelsk?
The gulf stream is the principal heat transporter in the North Atlantic. If it slowed down it would have a major effect on the quantity of heat transfered from the tropics to the Arctic. The simple fact that the Arctic is slightly warmer than the longterm average suggest that quite the opposite is happening, that the Gulfstream is transporting more heat than before.
It seems to me that they are not measuring what they think they measure.
Yes, and the children of the UK would not only know what snow is, they’d be shoveling it frequently during the winters.
“he was able to use mathematical models and simple physics to extend the reach of direct measurements”
” Piecuch’s analysis agrees with relationships seen in models between the deeper branches of the AMOC and the Gulf Stream”
Is he verifying a model with a model?
That’s how it reads to me.
yes…and claiming he can measure the speed by measuring sea level rise
…that’s like predicting temperature…by measuring tectonics
which, unfortunately, is not that far fetched for these idiots
If the current is running perpendicular to the coast, I could see changes in current speed impacting how much water piles up against the coast.
that’s a stretch……and sea level rise has been flat out consistent for over 100 years
using his own words against him….if sea level rise has not changed…then the speed of the current has not changed
“It’s turtles all the way down.”
Well of course. Models are the most accurate way of doing science. What would you expect him to verify a model with? Coarse human observation? That’s just anti-science.
At least the said that the current is weakest in the last century.
Most climate change papers would have said it was the weakest ever.
From the article: “If we can monitor something over the horizon by making measurements from shore, then that’s a win for science and potentially for society,” said Piecuch.”
“If” being the key word here.
I started to say Science isn’t what it used to be, but then again, it’s just like it used to be, with the addition that it is much more in the pubic eye now.
There have always been alarmists and skeptics, and there has been suppression of ideas for political reasons in the past, just like now.
We just have to have patience. The truth or falsity of the science will eventually come out.
Concerning the Earth’s climate, the actual facts will come out slowly, because the climate moves slowly, but even so, it is looking more and more like the Human-caused climate change speculation is nothing like reality. The temperatures are not cooperating with the meme.
Uh-ohs, this is how The Day After Tomorrow starts. Well, we can’t say they didn’t warn us.
Has this been critiqued here?
http://ocp.ldeo.columbia.edu/res/div/ocp/gs/
Obviously, flow in the near-surface, near-shore part of the Gulf Stream is going to be dependent on sea-level differences between Key West and Cape Hatteras.
It’s also going to depend on differences in water temperature and salinity. And not just surface temperature and salinity, but the entire profiles from surface to the bottom. These will determine what the sea level profile would be if there was no current. Deviations from this “neutral” sea-level profile will determine flow rates.
Too many unknown variables for this exercise to give meaningful conclusions, IMHO. Nice try, but I’m afraid that some unconscious bias may have crept in to make sure he got the anticipated result (“anthropogenic global warming has caused the Gulf Stream to slow down and if it continues to slow down western Europe will experience sudden catastrophic cooling”).
Also, I would question whether historic sea level measurements from tide gauges can be corrected for post-glacial isostatic rebound with sufficient accuracy for his purposes.
We all know the Gulf Stream creates a lot eddies as it flows off Hatteras and makes the turn Northeast? It isn’t a river flowing straight and true. How do you measure the net flow towards the North Atlantic?
If it has been slowing for a century, then it was not caused by anthropogenic CO2. It would be very interesting to see his methodology and plot the velocity as a function of time. I am going to make a WAG and predict that there was no sudden decrease in velocity corresponding to the increase in CO2. If that had been observed, the title of the paper would have been a bit different.
there are no current measurements from 50 much less 100 years ago .. not of the current … utter nonsense …
I get so disappointed when I think about how little logic is being applied to modern scientific questioning. If we want to measure the strength of the Florida Current, ought we not, several times per year, be dropping some highly iridescent, dissolving and biodegradable floating markers across the breadth of the flow, from Florida’s outer-most reef to Cuba and measuring the progress of those markers by aerial or space photography over the next few hours or days (after which time they dissolve with no damage to the local flora and fauna)? We could measure the Gulf Stream by doing the same with markers dropped into the water by plane from Freeport to Palm Beach and from Bermuda to Jacksonville. I mean seriously, who gives a crap about some minor gyre near shore, the sea level of which is already highly variable and has many potential confounding factors ready to act on it, from wind-blown water, to tides, etc.? If I were on the anti-sophistry patrol, I’d fault the latter for it’s potential for false signals and mischief, and I’d hope for something like the former, which after a period of years would form an unassailable record of the actual nature of the speed and power of those currents.
That would only tell us what the surface waters were doing. Also, since they are floating on the surface they would be pushed around by winds as well as water.
Periodic dropping of Argo floats spaced on a transect—say six equally spaced to span a 100 km width of the Gulf Stream off the coast of the Miami, Florida—would do the trick. They periodically profile from a depth of about 2000 m to the surface. At the surface, they transmit data, including their GPS-determined location, so this would provide an record of average Gulf Stream velocity across depth and width.
There are currently around 4000 Argo floats in all oceans of the world, excluding the Arctic Ocean.
They are thus relatively inexpensive instruments and are well-proven for accuracy and reliability.
Excellent idea, Gordon. I was under the impression that once an ARGO float device was dropped in the water, it could never be retrieved and tested/recalibrated, following the Josh Willis data deletion that should never have happened until the offending ARGO floats had been retrieved and retested for malfunctions and for ongoing accuracy BUT OF COURSE RETRIEVING AN ARGO FLOAT FOR TESTING MUST BE IMPOSSIBLE!
“he was able to use mathematical models”
Models. fuhgeddaboudit.
Global cooling, anyone?
I’ll take “Global Cooling” for $800, Alex.
John Holdren was Director at Woods Hole before joining the Obama admin
https://en.wikipedia.org/wiki/John_Holdren
This is deja vue all over again:
February 28, 2006 The Guardian
https://www.theguardian.com/environment/2006/feb/28/science.frontpagenews
A draft of the next influential Intergovernmental Panel on Climate Change
(IPCC) report will tell politicians that scientists are now unable to
place a reliable upper limit on how quickly the atmosphere will warm as
carbon dioxide levels increase. The report draws together research over
the past five years and will be presented to national governments in April
and made public next year. It raises the possibility of the Earth’s
temperature rising well above the ceiling quoted in earlier accounts.
Such an outcome would have severe consequences, such as the collapse of
the Greenland ice sheet and disruption of the Gulf Stream ocean current.
The shift in position comes as Tony Blair is expected to pledge today to
work towards a date for stabilising international greenhouse gas emissions
when he meets Stop Climate Chaos, the climate change equivalent of Make
Poverty History. The group is campaigning for a target date of 2015 for
stabilisation, saying a later date would endanger the planet.
What happened to that?