![436189main_atlantic20100325a-full[1]](https://wattsupwiththat.files.wordpress.com/2015/03/436189main_atlantic20100325a-full1.jpg?quality=83)
The findings are the result of a new monitoring technique, developed by oceanographer Josh Willis of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., using measurements from ocean-observing satellites and profiling floats. The findings are reported in the March 25 issue of Geophysical Research Letters.
The Atlantic overturning circulation is a system of currents, including the Gulf Stream, that bring warm surface waters from the tropics northward into the North Atlantic. There, in the seas surrounding Greenland, the water cools, sinks to great depths and changes direction. What was once warm surface water heading north turns into cold deep water going south. This overturning is one part of the vast conveyor belt of ocean currents that move heat around the globe.
Without the heat carried by this circulation system, the climate around the North Atlantic — in Europe, North America and North Africa — would likely be much colder. Scientists hypothesize that rapid cooling 12,000 years ago at the end of the last ice age was triggered when freshwater from melting glaciers altered the ocean’s salinity and slowed the overturning rate. That reduced the amount of heat carried northward as a result.
Until recently, the only direct measurements of the circulation’s strength have been from ship-based surveys and a set of moorings anchored to the ocean floor in the mid-latitudes. Willis’ new technique is based on data from NASA satellite altimeters, which measure changes in the height of the sea surface, as well as data from Argo profiling floats. The international Argo array, supported in part by the National Oceanic and Atmospheric Administration, includes approximately 3,000 robotic floats that measure temperature, salinity and velocity across the world’s ocean.
With this new technique, Willis was able to calculate changes in the northward-flowing part of the circulation at about 41 degrees latitude, roughly between New York and northern Portugal. Combining satellite and float measurements, he found no change in the strength of the circulation overturning from 2002 to 2009. Looking further back with satellite altimeter data alone before the float data were available, Willis found evidence that the circulation had sped up about 20 percent from 1993 to 2009. This is the longest direct record of variability in the Atlantic overturning to date and the only one at high latitudes.
The latest climate models predict the overturning circulation will slow down as greenhouse gases warm the planet and melting ice adds freshwater to the ocean. “Warm, freshwater is lighter and sinks less readily than cold, salty water,” Willis explained.
For now, however, there are no signs of a slowdown in the circulation. “The changes we’re seeing in overturning strength are probably part of a natural cycle,” said Willis. “The slight increase in overturning since 1993 coincides with a decades-long natural pattern of Atlantic heating and cooling.”
If or when the overturning circulation slows, the results are unlikely to be dramatic. “No one is predicting another ice age as a result of changes in the Atlantic overturning,” said Willis. “Even if the overturning was the Godzilla of climate 12,000 years ago, the climate was much colder then. Models of today’s warmer conditions suggest that a slowdown would have a much smaller impact now.
“But the Atlantic overturning circulation is still an important player in today’s climate,” Willis added. “Some have suggested cyclic changes in the overturning may be warming and cooling the whole North Atlantic over the course of several decades and affecting rainfall patterns across the United States and Africa, and even the number of hurricanes in the Atlantic.”
With their ability to observe the Atlantic overturning at high latitudes, Willis said, satellite altimeters and the Argo array are an important complement to the mooring and ship-based measurements currently being used to monitor the overturning at lower latitudes. “Nobody imagined that this large-scale circulation could be captured by these global observing systems,” said Willis. “Their amazing precision allows us to detect subtle changes in the ocean that could have big impacts on climate.”
Source: http://www.nasa.gov/topics/earth/features/atlantic20100325.html
h/t to WUWT reader Scott Gates
UPDATE: This story sent to me today was dated 3/25 and I originally thought it was new today. It was coincidentally 3/25 of 2010, not 2015. The first paragraph of the story has been changed to reflect this within 5 minutes of posting. h/t to Andrew Freedman – Anthony
I was just doing a little thought experiment, and would like someone or someones to tell me where I have gone wrong:
Gulf Stream is moving at normal usual speed, and each parcel of water spends a certain amount of time at tropical latitudes, during which time it absorbs solar energy and becomes warmer. As it flows through the Florida Straits and begins to move northward, at some point the parcel is no longer absorbing energy, but releasing the heat it gained to the atmosphere at higher latitudes.
If for any reason the Gulf Stream slows down, each parcel will be spending a longer amount of time at low latitudes than it was when the current was faster. Consequently, the parcel absorb more solar energy, and is heated to a higher temperature as it flows through the Straits and begins to move northward.
Since the water is hotter as it moves north, and spends a longer amount of time releasing it’s heat, there is more energy being released into the air as the stream moves first northeast and then more east by northeast.
Questions:
– Does the water max out at some point before moving north, and reach an equilibrium state at which it can get no hotter? Or does the zone of heated water get wider and deeper and the stream as a whole continue to gain energy?
– Does it release more heat at lower latitudes off the southeastern US and have less heat to release upon reaching the more northern states? Or is this effect negligible, and more heat is indeed delivered to the upper latitudes by having the GS move more slowly?
Brandon Gates is in rare form on this one. Are you really just a sock puppet for Mann? Nobody can be so stupid otherwise.
Mark
It’s not fair really, is it Mark? Brandon writes well and seems very knowledgeable on the subject, in comparison to most other commenters. I have had a very entertaining morning reading this thread.
However, some people don’t see it like that. They would prefer a simple slanging match with name calling. A game where no knowledge or expertise is required and thus more like a level playing field for them.
http://www.bishop-hill.net/blog/2014/12/2/niceness-at-home-and-abroad.html
MikeB,
That’s the expected nature of playing an away game against a hostile crowd that is loyal to a losing squad, and to a glaring fault. It really isn’t fair; I’m here by choice and feeling very much in my own element.
I appreciate your compliments on my writing and knowledge. I’m frankly not always sure the latter is justifiable; I have far more questions than answers and I know for a fact there are things I’ve gotten completely wrong. I’m glad you enjoyed reading, thank-you for saying so.
http://wattsupwiththat.com/2015/03/25/nasa-refutes-mann-and-rahmstorf-finds-atlantic-conveyor-belt-not-slowing/#comment-1891627
Mike, please read my three posts in succession starting here, linked above.. BG uses advanced troll tactics very well, and has technical knowledge of some aspects of CAGW, but is very wrong, and he slings plenty of mud. Forgive the typos here, as it is very late and I did zero proofing, so please do not miss the message due to the substandard writing.
David A,
My main argument is extremely simple. Here, again, is Anthony’s headline and lead text:
NASA refutes Mann and Rahmstorf – Finds Atlantic ‘Conveyor Belt’ Not Slowing
From the “we told you so yesterday” and the “settled science” department. This study was released in 2010, and they used actual measurements, rather than proxy data and reconstructions like Mann did. Gee, what a concept! NASA Study Finds Atlantic ‘Conveyor Belt’ Not Slowing 03.25.10
The implicit accusation is that Ramstorf et al. (2015) does not use “actual measurements” and disagrees with what the “reality” of these so-called “actual measurements” tell us about what’s going with currents in the Atlantic. This implication is patently false. From the paper itself, Figure 5 and its caption:
Figure 5. A compilation of different indicators for Atlantic ocean circulation. The blue curve shows our temperature-based AMOC index also shown in b. The dark red curve shows the same index based on NASA GISS temperature data48 (scale on left). The green curve with uncertainty range shows coral proxy data25 (scale on right). The data are decadally smoothed. Orange dots show the analyses of data from hydrographic sections across the Atlantic at 25° N, where a 1 K change in the AMOC index corresponds to a 2.3 Sv change in AMOC transport, as in based on the model simulation. Other estimates from oceanographic data similarly suggest relatively strong AMOC in the 1950s and 1960s, weak AMOC in the 1970s and 1980s and stronger again in the 1990s (refs 41, 51).
The cited NASA study, written by Josh Willis of JPL mainly covers the ARGO era, though some cautious inferences are suggested back to 1992 based on satellite altimetry: http://onlinelibrary.wiley.com/doi/10.1029/2010GL042372/full
[21] No significant trend was detected in AMOC transport between 2002 and 2009. The altimeter record, however, suggests a slight strengthening since 1992. Although agreement with Argo-based observations during the latter years is encouraging, some care is required for interpreting the altimeter-based estimate over the entire 16-year period. Regression coefficients between altimeter observations and individual profiles are 0.5 to 0.6, while regression coefficients with subsurface displacement data are closer to 0.3 [Willis and Fu, 2008]. Nevertheless, on long enough time scales, temperature and salinity anomalies advected into the domain could introduce significant error into these coefficients. This underscores the need for ongoing hydrographic observations such as those obtained by the Argo floats as well as the more traditional ship-based surveys.
No significant trend between 2002 and 2009. Altimetry suggests a slight strengthening since 1992. Both statements agree with Ramstorf et al. (2015), Fig. 5. Both statements agree with the Abstract as quoted very early in the comment thread by Nick Stokes: Here we present multiple lines of evidence suggesting that this cooling may be due to a reduction in the AMOC over the twentieth century and particularly after 1970. Since 1990 the AMOC seems to have partly recovered.
“NASA refutes Mann and Rahmstorf” is a false statement. It is an “argument” that was dead on arrival. Any honest, rational person with basic language comprehension skills and the desire to be correct about salient details, like methods and time frames, can easily figure this out. My “advanced troll tactics” are nothing more than basic reading and critical thinking skills, otherwise known as exercising proper skepticism. You know, the opposite of ignorant Gish-galloping buffoonery.
Or perhaps you don’t, in which case I really ought to lay off mocking your “illiteracy”.
Actually Brandon it is best to quote from the post what you disagree with. (You really need to stop arguing with the entire community of WUWT, it causes you to make inevitable strawman assumptions, to miss the cogent criticisms, and apply snark when it is juvenile.) WUWT is a large community.
Now from the post…
“The latest climate models predict the overturning circulation will slow down as greenhouse gases warm the planet and melting ice adds freshwater to the ocean. “Warm, freshwater is lighter and sinks less readily than cold, salty water,” Willis explained.”
Did you disagree with that?
“Combining satellite and float measurements, he found no change in the strength of the circulation overturning from 2002 to 2009. Looking further back with satellite altimeter data alone before the float data were available, Willis found evidence that the circulation had sped up about 20 percent from 1993 to 2009”
Did you disagree with that?
Your posted a graph from the Mann & Rahmstorf paper, based on… “The blue curve shows our temperature-based AMOC index also shown in b. The dark red curve shows the same index based on NASA GISS temperature data48 (scale on left). The green curve with uncertainty range shows coral proxy data25 (scale on right)
=================================
? Where, in this graph is the data from Willis NASA study, applying apples to apples to the same section of the AMOC in Mann’s paper)
By apples to apples I mean that Mann & Rahmstorf did not measure any components of the AMOC flow, and they attempt to attribute to your SUVs emission something that the NASA paper clearly stated was natural,… “For now, however, there are no signs of a slowdown in the circulation. The changes we’re seeing in overturning strength are probably part of a natural cycle,” said Willis. “The slight increase in overturning since 1993 coincides with a decades-long natural pattern of Atlantic heating and cooling.”
So it is Mann’s postulated SLOWDOWN, which is not measured, and his empty causation link to your SUV, which is AT ODDS with the NASA study, and other studies more recent directly measuring the current and salinity.
Mann admits that he is not talking about any Gulf stream component of the AMO slowing down, as it is known not to be, and to be primarily wind driven. Yet, and here is the post normal part of CAGW science you do not face…
Jamie posted…”Mann allows himself to be quoted as saying that it may be only a matter of DECADES before a permanent shutdown of the North Atlantic Gulf Stream occurs. His recent FB timeline is crammed FULL of links to articles and interviews with himself which are predicting catastrophic slowdown/shutdown of the GULF STREAM. Here’s just one:
http://ecowatch.com/2015/03/25/global-warming-slowing-ocean-currents-michael-mann/
Where is the evidence for the big slow down from the other papers?
It is not there is it?
In fact, Mann is talking about this slow down in the thermohaline circulation of the AMOC at a time when Greenland has been accumulating ice again for the past 3 years at a rate now exceeding 200gt/yr per http://www.dmi.dk/en/groenland/.
…and Mann ignores that RAPID study, or misappropriates what it says, which is based on seafloor to surface tethered buoys measuring T, salinity, and current velocity, and does not support his study either.
BTW Brandon, I did NOT notice you mocking my literacy skills. I apologized to a poster for not proof reading, as well as for an old browser and keyboard, but please understand that my misplacing a comma, is not an excuse for your CAGW coma.
David A,
Normally I do. I had two posts to you to answer, one of which attacked my tactics, the other of which was filled with off-point irrelevancies by my judgement. So I triaged and combined here.
I don’t need to do anything. It may be advisable for me to lay down the broad brush since I recognize how odious it is to use it and that cuts against the grain of my better nature. But the plain fact of the matter is the utter lack of collective self-awareness at WUWT about juvenile behavior and unfairly sweeping condemnation when the subject is Dr. Michael E. Mann is so wildly hypocritical in my mind that the personal satisfaction which comes from venting my spleen takes precedent.
If you want to tone troll someone, I suggest that you’d be better served policing your own on this topic. You’ll get no quarter from me on this topic in this thread by suggesting what’s “best”, only leading. I ask none in return, and certainly don’t expect to get it.
Recognized and appreciated. Not every day, but frequently enough I’ve had some exchanges which I thought were rewarding.
No. It’s perfectly logical and based on basic physical principles I know firsthand.
Haven’t I quoted that bit already? I see no reason to disagree with it.
Why are you asking ONLY me? Anthony’s contention is that Willis (2010) refutes Rahmstorf (2015). Which is silly:
http://onlinelibrary.wiley.com/doi/10.1029/2010GL042372/full
[9] Because they dive to a depth of approximately 2000 meters to obtain temperature and salinity profiles, the Argo floats do not sample the currents in shallow regions like the continental shelf or the upper part of the continental slope. Argo-based estimates of geostrophic velocity are therefore restricted to regions where the water is deeper than 2000 m (Figure 1). This precludes using Argo to estimate the AMOC at latitudes where significant meridional transport lies in shallow regions. For instance, at 33°N, much of the Gulf Stream transport sits on the continental shelf and slope (Figure 1). Because Argo cannot sample these shallow regions, the Argo-based estimate misses much of this northward transport and gives a basin-integrated transport that is much too low (Figure S1).
Not only does ARGO not “refute” Rahmstorf (2015), it looks to me like they were correct to not use Willis (2010) for the “Gulf Stream” transport at 33°N.
It’s a big ocean, David. The texts of these papers include specifics. Press releases unfortunately use ambiguous terms in ways that aren’t always obviously inappropriate to the PR flacks who write them, nor to the ones who uncritically regurgitate (and/or spin) them elsewhere. One has to read the papers to get the salient, critical details before making conclusions. Anthony was so sloppy on the year Willis (2010) was published (“This was just released today”), it was painfully obvious that he didn’t read the damn thing before declaring triumphantly:
“NASA refutes Mann and Rahmstorf – Finds Atlantic ‘Conveyor Belt’ Not Slowing”
I think you’re asking the wrong guy the wrong questions about the wrong issue.
Brandon Gates March 26, 2015 at 12:53 pm
Replace arrogance for ambition in the quote above and you might find a cautionary note regarding your
self-confessed thick skin.
On more than one occasion you have been outrageously insulting to the host of the forum in
which you so pleasurably parade your inflated ego.
You tauntingly derided Anthony’s ability to read on a previous thread and again here you colour him: stupid, illiterate, incapable of basic reading, or critical thinking, his argument dead on arrival and you accuse him of being an improper skeptic, lumped in with those you label; ‘Gish-galloping buffoons’.
However, If you read these papers with the slightest notion of what intellectual honesty is, you can only come to the same conclusion that Anthony did. And that is, that NASA refutes the claims of Mann and Rahmstorf (Albeit in the very paper they reference).
You posted the paper’s figure five and its caption in defence of your claim that Anthony’s position is “patently false”. Yet the figure only confirms Anthony’s “implication” because nothing depicted in it is real data!
It is worse than you thought, because they have only used proxies. Proxy temperature reconstructions are used as proxy data for the AMOC index (A proxy) for the current circulation. In the case of the hydrological model data, it is a proxy of a proxy of a proxy.
Here is a listing of the indictors (Indexes/proxies) depicted in figure 5, which is “A compilation of different indicators for Atlantic ocean circulation”:
1. M&R’s Temp based AMOC index
2. NASA GISS Temp based AMOC index
3. Coral proxy based AMOC index
4. Hydrographic model simulation
And further, the caption’s only overt reference to the NASA paper, is to the 1990s being “stronger again”. The comment: “other estimates from oceanographic data similarly suggest…”, is not appropriate or even relevant to the NASA paper because it goes out of its way to cast doubt on the veracity of those very claims:
As to the 1990s speeding up, the NASA paper does mention a “slight strengthening since 1992” but cautions that this “data” is from the Altimeter record only and not from Argo-based observations. The paper specifically warns against the use of this Altimeter data because of the accumulation of significant error and therefore recommends real observations! :
To summarise, NASA concluded that slowing did not occur in the seven years prior and that it is unlikely to have occurred in the previous 20 years. It also states that any slowing trend from 1957 is not verified by more recent mooring data.
Thus, Anthony is perfectly justified to state that real data isn’t used by the Mann and Rahmstorf paper and that NASA did use real observations to show that cooling and slowing had not occurred over the entire period in question.
The upshot is that the graph your exhibited as evidentiary, is not compatible with any real observation at any point over the period it “documents”.
BG, your “basic reading and critical thinking skills” have just been hit out of the park.
They must seem smaller to you now, as they recede over the outfield wall.
Scott Wilmot Bennett,
As I have already pointed out, it’s extremely unlikely Anthony read either paper prior to posting this article.
That was me giving him the benefit of the doubt.
Yes, I’ve already quoted that passage in a response to David A. You’re behind the curve here.
No, as you yourself note:
Two modern instrumental series, one proxy series, and a model. That is not “only” proxies.
Specifics. Not just when but WHERE is important here. Speaking of WHEN, 20 years is nothing when it comes to the AMOC, with transit times on the order of 1,000 years. Kinda sorta why coral proxies make sense because for darn sure corals have been around longer than buoys. They’ve even been around longer than buckets tossed over the rail of ships. Models make the utmost sense because the whole idea of this exercise is to predict what’s going to happen in the future, and that begins with doing runs over the past and present and comparing that output to the best observational data available.
Only someone completely scientifically illiterate or wholly dishonest would try to punch holes in Rahmstorf (2015) for including all 4 of those above items in their study. It’s quite possible for someone to be both of those two things at the same time. I think it’s pretty clear what my opinion is on Anthony in that respect. I don’t suffer his apologists any more gladly.
Ibid.
I think not. You are running the same idiotically obtuse game that Anthony and David A are. It’s a big ocean. Plucking statements about the Atlantic out of one paper and applying them to another paper about the Atlantic without being geographically specific is not a viable way to compare these two papers. And the a priori conclusion that Rahmstorf (2015) is wrong because Willis (2010) says so is patently illogical and almost beyond belief save for the fact that I see such sloppy thinking here day after day after day.
Mike, here I discuss some of Brandon’s methods. http://wattsupwiththat.com/2015/03/25/nasa-refutes-mann-and-rahmstorf-finds-atlantic-conveyor-belt-not-slowing/#comment-1891618
Again, please look past the non edited writing, and see the message presented.
The article says:
>>”Scientists hypothesize that rapid cooling 12,000 years ago at the end of the last ice age was triggered when freshwater from melting glaciers altered the ocean’s salinity and slowed the overturning rate. That reduced the amount of heat carried northward as a result.”
Anyone know what proxy is used to assess this? Or what method?
It seems to me there’s alternative explanations. For example Ewing and Donn (in 1958) hypothesised that *if* the arctic were open water at that period it could have had a similar effect:
1) Warm atlantic currents melt the ice cap over centuries
2) The ocean below can now radiate (& evaporate) as it is no longer shielded/insulated from the air, so the energy in the warm currents can be lost to space and atmosphere.
3) Over centuries the 14 billion sq m of arctic ocean loses heat to space
4) Which cools the planet down again. Snow builds up, ice forms until the ice-cap grows over again.
5) Once again the warm atlantic ocean builds up heat until we are back to 1)
It makes a lot of sense to me. The ice-cap acts like a thermostat in a car: it opens to allow heat to escape, and closes to retain heat. It fits the rapid change from one ice-age to another, as in this graphic:
http://earthguide.ucsd.edu/virtualmuseum/images/raw/IA_Fig7_0_4.jpg
When the ice-cap is complete, heat builds rapidly (at 150k years and 20K years ago in the graphic). Then the ice slowly melts again as a result and heat can escape, which gives the jagged downward slope of temperature as the earth loses heat again.
It explains the inconstancies in the Milankovitch cycles theory, as orbital changes are a) gradual, b) don’t have enough energy in themselves to melt the ice (so a high CO2 sensitvity is invoked), and c) the deglaciation only happens every 5th cycle.
Oh, and I should add, it appears that there’s good evidence that man was living in the Arctic during the last ice age (see here and here. This implies that much of the Arctic region was ice free / temperate during the last ice age.
“..Willis found evidence that the circulation had sped up about 20 percent from 1993 to 2009.”
Which is what I was hinting at here:
http://wattsupwiththat.com/2015/03/24/michael-mann-and-stefan-rahmstorf-claim-the-gulf-stream-is-slowing-due-to-greenland-ice-melt-except-reality-says-otherwise/#comment-1890555
in my opinion the “Great Conveyor” did not even slow at the start of the Younger Dryas and I contend further as I have said in my book that the cause of the Younger Dryas was an encounter with a comet, Rod Chilton
“Achilles Heel of the North Atlantic”
“The North Atlantic is particularly important for global ocean circulation, and therefore for climate worldwide,” Reichler says. “In a region south of Greenland, which is called the downwelling region, water can get cold and salty enough – and thus dense enough – so the water starts sinking.”
http://unews.utah.edu/news_releases/stratosphere-targets-deep-sea-to-shape-climate/
http://www.nature.com/ngeo/journal/v5/n11/full/ngeo1586.html
The Atlantic meridional overturning circulation (MOC) has not slowed down in the past 8,000 years. Past perturbations of MOC were caused by drainage of Lake Agassiz, which raised sea level by 0.8 to 2.2 m.
http://www.sciencedirect.com/science/article/pii/S0012821X11003177
20th century melting of glaciers raised sea level by only 0.002 to 0.003 m per year. This melt rate has not change much in 8,000 years. See chart
http://upload.wikimedia.org/wikipedia/commons/1/1d/Post-Glacial_Sea_Level.png
Coming (intentionally) late into this discussion, just a short note:
Earth’s magnetosphere ‘pulsates’ with periodicity of about 60 year, while the Earth’s core at just above 65 years, together speeding or slowing down, rising, pausing or declining the events
http://www.vukcevic.talktalk.net/Ms-Ec.gif
Perhaps the slowdown in the circulation his hiding deep within the oceans with all of the accumulated warmth.
There was a warm SST pattern south and east of Greenland during the Nov 2009 to Mar 2010 low AMOC event. Here’s the mid 2012 low AMOC SST pattern, again during stronger negative NAO conditions:
http://weather.unisys.com/archive/sst/sst_anom-120715.gif
” From 1 April 2009 to 31 March 2010, the annually averaged MOC strength was just 12.8 Sv, representing a 30% decline. This downturn persisted from early 2009 to mid-2010. We show that the cause of the decline was not only an anomalous wind-driven event from Dec 2009–Mar 2010 but also a strengthening of the geostrophic flow. In particular, the southward flow in the top 1100 m intensified, while the deep southward return transport—particularly in the deepest layer from 3000–5000 m—weakened. This rebalancing of the transport from the deep overturning to the upper gyre has implications for the heat transported by the Atlantic.”
http://onlinelibrary.wiley.com/doi/10.1029/2012GL052933/pdf