From Woods Hole Oceanographic Institution via Eurekalert
Newly discovered Icelandic current could change North Atlantic climate picture
An international team of researchers, including physical oceanographers from the Woods Hole Oceanographic Institution (WHOI), has confirmed the presence of a deep-reaching ocean circulation system off Iceland that could significantly influence the ocean’s response to climate change in previously unforeseen ways.
The current, called the North Icelandic Jet (NIJ), contributes to a key component of the Atlantic Meridional Overturning Circulation (AMOC), also known as the “great ocean conveyor belt,” which is critically important for regulating Earth’s climate. As part of the planet’s reciprocal relationship between ocean circulation and climate, this conveyor belt transports warm surface water to high latitudes where the water warms the air, then cools, sinks, and returns towards the equator as a deep flow.
Crucial to this warm-to-cold oceanographic choreography is the Denmark Strait Overflow Water (DSOW), the largest of the deep, overflow plumes that feed the lower limb of the conveyor belt and return the dense water south through gaps in the Greenland-Scotland Ridge.
For years it has been thought that the primary source of the Denmark Overflow is a current adjacent to Greenland known as the East Greenland Current. However, this view was recently called into question by two oceanographers from Iceland who discovered a deep current flowing southward along the continental slope of Iceland. They named the current the North Icelandic Jet and hypothesized that it formed a significant part of the overflow water.
Now, in a paper published in the Aug. 21 online issue of the journal Nature Geoscience, the team of researchers—including the two Icelanders who discovered it—has confirmed that the Icelandic Jet is not only a major contributor to the DSOW but “is the primary source of the densest overflow water.”
“In our paper we present the first comprehensive measurements of the NIJ,” said Robert S. Pickart of WHOI, one of the authors of the study. “Our data demonstrate that the NIJ indeed carries overflow water into Denmark Strait and is distinct from the East Greenland Current. We show that the NIJ constitutes approximately half of the total overflow transport and nearly all of the densest component.
The researchers used a numerical model to hypothesize where and how the NIJ is formed. “We’ve identified a new paradigm,” he said. “We’re hypothesizing a new, overturning loop” of warm water to cold.
h/t to Dr. Leif Svalgaard
The results, Pickart says, have “important ramifications” for ocean circulation’s impact on climate. Climate specialists have been concerned that the conveyor belt is slowing down due to a rise in global temperatures. They suggest that increasing amounts of fresh water from melting ice and other warming-related phenomena are making their way into the northern North Atlantic, where it could freeze, which would prevent the water from sinking and decrease the need for the loop to deliver as much warm water as it does now. Eventually, this could lead to a colder climate in the northern hemisphere.
While this scenario is far from certain, it is critical that researchers understand the overturning process, he said, to be able to make accurate predictions about the future of climate and circulation interaction. “If a large fraction of the overflow water comes from the NIJ, then we need to re-think how quickly the warm-to-cold conversion of the AMOC occurs, as well as how this process might be altered under a warming climate,” Pickart said.
“These results implicate local water mass transformation and exchange near Iceland as central contributors to the deep limb of the Atlantic Meridional Overturning Circulation, and raise new questions about how global ocean circulation will respond to future climate change,” said Eric Itsweire, program director in the U.S. National Science Foundation (NSF)’s Division of Ocean Sciences, which funded the research.
The Research Council of Norway also funded the analysis of the data.
Pickart and a team of scientists from the U.S., Iceland, Norway, and the Netherlands are scheduled to embark on Aug. 22 on a cruise aboard the WHOI-operated R/V Knorr to collect new information on the overturning in the Iceland Sea.
“During our upcoming cruise on the Knorr we will, for the first time, deploy an array of year-long moorings across the entire Denmark Strait to quantify the NIJ and distinguish it from the East Greenland Current,” Pickart said. “Then we will collect shipboard measurements in the Iceland Sea to the north of the mooring line to determine more precisely where and how the NIJ originates.”
In addition to Pickart, authors of the Nature Geoscience study include Michael A. Spall, and Daniel J. Torres of WHOI, lead author Kjetil Våge, a graduate of the MIT-WHOI joint program now with University of Bergen, Norway, Svein Østerhus and Tor Eldevik, also of the University of Bergen, Norway, and Héðinn Valdimarsson and Steingrímur Jónsson—the two discoverers of the NIJ—of the Marine Research Institute in Reykjavik, Iceland.
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, 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.
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See this previous WUWT article on the East Greenland Current, for which no trend was found. Study of the East Greenland Current finds no trend
@Theo Goodwin August 21, 2011 at 7:57 pm:
Yes, right.
The TYPICAL SCIENTIFIC DISCOVERY SCRIPT
1. EXPERTS AT WORK. Yesterday/last month/last year scientists were all “We are the experts, you know nothing (in fact, are incapable of knowing anything) and we know everything – absolutely everything – about this subject, and the way it works is this: [yadda yadda yadda], so sit back down, STFU, and give us more funding.”
2. YON HUMBLENESS OF SCIENTISTS FLOWETH OVER. Something totally comes along – something they never saw coming – which blows yesterday’s “God’s revealed unto scientists truth” out of the water, and for a moment scientists act all humble and say things like, “Well, science is a humbling experience – We never saw this coming, and we have to revise the whole history of everything now. Thus goes scientific progress. We who are as nothing kneel before its altar, humble in the extreme.”
3. EXPERTS AGAIN, HARD AT WORK. Tomorrow (next year), scientists all return to the academic puffed-up-edness, and go back to 1. above and start over again.
I get so aggravated at this never-ending cycle of “We know everything > we are humble servants of honest inquiry > NOW we know everything… We know everything > …” And each time around, their chests puff out even more. Basically, we pay them to puff their chests out.
And we, who yesterday were told to accept yesterday’s truth as eternal, are now told to pay no attention to the man behind that old curtain, are supposed to do memory wipes, and we are not to realize this simple truth:
Yesterday they were wrong.
Today is tomorrow’s yesterday, so, how can we accept today’s truth as they tell it, knowing it will be tomorrow’s man behind the curtain? Best we think for ourselves, taking their side into account, but deciding for ourselves. After all, hasn’t almost every scientific interpretation in history eventually been supplanted by a new one?
The truth of the matter is that right now science is somewhere along the continuum between utter ignorance and all-knowing, with most of the knowing out ahead of us.
But this one came out of Woods Hole, the institute that (with East Anglia) in the 1970s brought us The Oncoming Ice Age. (See the article above, “Climate predictions in 1974 – Famous glaciologists predicted the world going colder from 1974 until 2010.”) So, count on it being wrong sooner, rather than later.
@jorge August 21, 2011 at 8:10 pm:
The 20-20 hindsight version of science continues…
Now it WOULD have been real science, if only they had PREDICTED the existence of this current.
I LOVE the tone of the comments on this thread! 🙂
I have yet to see any strong evidence of the North Atlantic having substantially increased fresh water influx. If anything, there is an ever decreasing influx as the long trailing edge of the great melt withers away.
Probably one of top places I’d be looking for freshening would be the Gulf of Mexico, witness what has happened over the past year vis a vis the greater Mississippi system.
Instead of wasting money on supercomputers
(wait ten years and get them at Best Buy)
they should be funding a huge oceanographic fleet to do actual measurement (i.e., science).
But that would mean firing a Dilbert-cubicle horde
and hiring thousands of nautical roustabouts capable of running said fleet.
Guess which of these competing castes has the greater lobbying power?
Not an insignificant number of elements on the periodic table were predicted to be there (in fact the scientist was sure about it) but little was known about what they might look like in detail. That there was an inkling about what to look for and where to look was based on a model. Just food for thought. Let’s not throw the baby out with the bath water.
In the 60s and 70s oceanographers were grumbling that more was known about the surface of the moon than the ocean deeps. Radioactive fallout from nuclear testing 50 years ago provided a way of tracking currents, which the US military seized on for obvious reasons, and the Navy and others have continued to map lateral and vertical mixing by injecting dyes into the ocean, and the dispersion of the plumes can be tracked by satellites. It’s a fascinating area of research, and the bits I’ve focussed on here are just a small part of it.
I think you mischaracterise Wunsch’s opinions (I’ve been reading his papers over the last few days by coincidence). He does question conventional wisdom on the thermohaline current, but not as you put it. And be careful pushing notions around here that are based on numerical models! 🙂
Not at all, he has suggested that winds and tides can account for nearly all the energy needed for overturning, but whether these mechanisms are the sole, primary or secondary cause of the putative thermohaline ‘conveyer belt’, it doesn’t matter a great deal for AOGCM outputs. What is more troublesome is vertical mixing rates, and this has particular application to equilibrium climate sensitivity and climate model output. Wunsch’s inquiries primarily call into question the timing of oceanic thermal response to temperature changes in the atmosphere. He himself has no doubt that anthropogenic warming is an important issue that needs to be addressed – cf his letter of complaint to Martin Durkin, producer of The Great global Warming Swindle, who Wunsch says selectively edited his segment to misrepresent his analysis.
No scientific theory is ever finally settled.
The heating of the atmosphere on a global scale due to anthropogenic emmissions of greenhouse gases is so well established by empircal evidence and theory that it is now mainstream science.
The details of where, when and how much are much less understood known and this is the subject of continuing research.
Pamela Gray says:
August 22, 2011 at 9:00 pm
Actually the properties of the elements were predicted because of where the gaps in the periodic table were.
Also, Newton’s model of the universe led to the prediction of previously unknown planets.
Newton was regarded as the absolute pinnacle of science for a couple of centuries, as close to “settled” as it was possible to be. But there were problems. The orbit of Mercury seemed to require another planet, Vulcan, which was not there. Then came relativity and quantum theory which provide our best understanding of the universe – for now.
That is how scince works. There are models, there is consensus, but they are never permanent and always subject to challenge, revision and possibly overturning.
But until the better explanation comes along, you use that consensus or model as the basis for understanding and further work and progress.
After revisiting my notes, I am inclined to think that the North Icelandic Jet is more likely to be a reconfiguration of the existing deep cold water flow. Denmark Strait is relatively shallow (max depth 600m, see bathymetry graph in: http://www.vukcevic.talktalk.net/LFCa.htm )
Denmark Strait is one of more extensively investigated area http://www.ices.dk/ocean/project/veins/GraphSum.htm
it would be surprising that presence of a major current was not detected previously.
Steve Garcia, your characterisation of how science is conducted is utterly fatuous. Scientists are not very interested in what they know, except as a means of extending our knowledge.
Scientists like me spend our time confronting our ignorance, trying to understand and explain what we do not know, using what we do know to make new discoveries.
Not all discoveries involve confirming predictions.
Watson and Crick did not discover the double helical structure of DNA because someone predicted it. They used what was known about chemical bonding and the interpretation of X-ray crystallographic data to determine that the structure was a helix with a sugar phosphate backbone and base pairs.
Philip Shehan says:
August 23, 2011 at 2:28 am
No scientific theory is ever finally settled.
The heating of the atmosphere on a global scale due to anthropogenic emmissions of greenhouse gases is so well established by empircal evidence and theory that it is now mainstream science.
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I will ask you again – what is the empirical evidence ??
Please confront your ignorance.
No links. No appeals to authority. No telling us all what a great scientist you are. Just state in however many words you want, what the empirical evidence is that anthropogenic greenhouse gases cause a heating of the atmosphere on a global scale..
But there’s so much. What do you think is missing?
Empirical evidence…
1) the surface of the earth emits long wave radiation
2) carbon dioxide is present in the atmosphere
3) carbon dioxide absorbs long-wave radiation
4) the amount of carbon dioxide in the atmosphere has been increasing for over a hundred years
5) the increase of the last 150 years has been largely caused by human activities
5a) the anthropogenic contribution is empirically determined by measuring isotopic ratio changes over time
6) the average temperature of the globe has increased over the last 100 years
That’s your empirical evidence. It’s not ‘proof’, but it’s the evidence you’re asking for. The details, especially on smaller time scales, require more explanation.
Other evidence includes
7) the amount of outgoing long-wave radiation in the spectrum absorbed by CO2 has decreased, as measured by satellite readings over many years, in line with what is expected from increased CO2 in the atmosphere
8) the stratosphere has been cooling, which is what is expected with increased CO2 (but the opposite if the heating was solar-driven)
9) atmospheric oxygen levels have dropped consistent with burning fossil fuels (oxygen atoms bonding to carbon)
Anyone positing that more CO2 won’t change the energy balance of the atmosphere, or that the rise of CO2 over the last 150 years is NOT mostly from human activity, or that there is no evidence, empirical or otherwise, that human activity is raising the temperature of the planet – is no longer participating in reality-based discussion.
There are plenty of components that can legitimately be argued argued about, like climate sensitivity (how much the globe might warm), the role of clouds, dust and aerosols in the global energy budget, ocean dynamics, and policy implications. There’s still room to argue that the change won’t be much, and that adapting will be better than mitigating. But some elements of the debate are known ‘beyond reasonable doubt.’
barry says:
“Empirical evidence…
1) the surface of the earth emits long wave radiation
2) carbon dioxide is present in the atmosphere
3) carbon dioxide absorbs long-wave radiation
4) the amount of carbon dioxide in the atmosphere has been increasing for over a hundred years
5) the increase of the last 150 years has been largely caused by human activities
5a) the anthropogenic contribution is empirically determined by measuring isotopic ratio changes over time
6) the average temperature of the globe has increased over the last 100 years”
It may surprise you, barry, but I agree with all those points. However, there is no empirical evidence showing that CO2 causes rising temperatures. None. It may well be a cause of rising temperature. But the evidence is missing. It could just as well be temperatures naturally rising on the trend line from the LIA – coincidentally along with rising CO2. You have provided zero evidence that CO2 is the cause, and your added points are just as specious. It may be that CO2 causes warming. But without testable evidence confirming that conjecture, the null hypothesis remains unfalsified. Stick to the scientific method, and you won’t go wrong.
Wunsch is not the only oceanogapher who sees through the myth of “the great conveyor belt.” The great wind-driven ocean currents that do affect climate are not materially dependent upon snail’s-pace thermohaline processes. But that fiction is necessary to maintain the link to climate-research FUNDING.
Jim Steele says:
August 21, 2011 at 8:38 pm
My previous comment was meant to second yours.
Hi Smokey,
You’ll have to elaborate, because if you agree with those points, then I don’t see how you can depart from the conclusion.
Empirical evidence is stuff that can be measured and confirmed to be *true* and used to infer other stuff. We know that if you increase the amount of CO2 in a volume receiving steady heat in the lab, the volume will heat up as the CO2 rises. That is an empirical fact, demonstrated by Tyndall in 1858 (published 1959) and corroborated in professional and high school labs a zillion times ever since. This is the kind of evidence that is ‘beyond all reasonable doubt.’
Googling up the Tyndall paper, I came across this marvelous little monograph, which says that one Eunice Foote made a presentation three years earlier than Tyndall, demonstrating the effect of increased heat from rising CO2.
http://www.searchanddiscovery.com/documents/2011/70092sorenson/ndx_sorenson.pdf
Noice bit of history.