I posted on how Europe might end up cooler rather than warmer as a consequence of global warming and its affect on ocean currents, click here for the post.
Following the post, a reader of this blog, Phil Done, suggested in response to a comment from Ian Mott, that Mott really should read up on the phenomenon at Wikipedia.
Mott, who likes working things out for himself, has had a read at Wikipedia and done a bit of a general google and emailed me his findings as follows:
A check of the first pages of google sites dealing with the claimed ice age that would be produced by the collapse of the ‘Atlantic Conveyor’ reveals some interesting stuff. Most carry vague descriptions of how this would take place and seem to indicate that it will be caused by a change in northern salinity levels due to melt water from the Greenland Ice Sheet that will prevent this less dense water from submerging and thereby altering the flow pattern. Most carry the claim that evaporation from the gulf stream currently make this body of water very saline and more dense than the rest of the ocean. All point to the disruption of this salinity level by fresh melt water as the primary agent of disturbed flow pattern.
A good example is http:www.enviroliteracy.org/article.php/545.htm which has a curious link to a graphic called “The Atlantic Thermohaline Circulation” at www.clivar.org/publications/other_pubs/clivar_transp/pdf.files/ . Now the most curious thing about this graphic is that the Gulf Stream is shown as flowing due east from New York to Portugal before heading north past the UK. The generally accepted route up the US east coast appears to have been an inconvenient fact to be ignored for the sake of the story. Even more curious is a “cold, saline bottom current” heading north past New Zealand, through the shallows of Vanuatu into the far north pacific where it surfaces between Alaska and Kamchatka where, curiously, it is supposedly warmed in this sub-arctic clime for the journey south.
The brightest spot was at www.awitness.org/column/global_warming_ice_age.html that rightly pointed out that the mini-iceage of the 1400’s was no such thing and that the other common example provided 12000 years ago was actually a slight pause in the middle of a period of glaciation with little relevance to this scenario.
But it is the actual numbers involved that reveal the truth. According to www.encyclopedia.com/html/G/GulfS1tre.asp the initial speed of the Gulf Stream is 6.4km/hour over a width of 80km. This slows further north as it widens so for the sake of this analysis we assume the Gulf Stream/North Atlantic Current has a median flow of only 3.6km/hr, is 100km wide and about 500m deep. At this speed the entire trip from Florida to Iceland will only take 70 days. And even assuming zero rainfall, the maximum evaporation is only likely to be 70/365 days x 2000mm evaporation = 383mm evaporation per cycle. And this means the 500 metre thick water column is left to absorb the salt reserves of 0.383 metres of evaporated water before it heads south again. As normal ocean salt level is 3.5% then the 499.617 remaining metres of the water column absorbs 3.5% of 0.383 metres of water, a total of 13.4 millimetres of salt that is added to the 17.5 metres of salt in the column. This is an increase of only 0.07657 of 1%.
And as for the claimed impact of fresh water on the current, we have a total of 180 km3 of water flowing past any given point in the north atlantic each hour. This amounts to 1.577 million km3 each year which disperses into the approx 160 million km3 North Atlantic (40 million km2 x average depth of 3.926km). This north atlantic data is derived from the whole of atlantic data from http://en.wikipedia.org/wiki/atlantic_ocean .
The entire ice volume of Greenland is only 2.44 million km3 so a complete melt over a highly improbable twenty years would add only 0.122 million km3 to the annual current flow of 1.577 million km3, for a total of 1.699 million km3 pa. The existing salt in the NA Current, at 3.5% of volume, will be 0.055195 million km3. And this will only reduce the salinity level of the combined current and melt water by one 14th to 3.25%.
A slightly less improbable 100 year total melt, but still very rapid in climatic terms, would involve only 0.0244 km3 per annum. This would produce a combined flow of 1.6014 million km3 with a salinity of 3.45%. This range is only half the variation normally observed within a 1000 metre ocean profile. See www.windows.ucar.edu/tour/link=/earth/water/salinity_dept
In summary:
The North Atlantic currents are horizontal cycles that flow in a clockwise direction due to the rotation of the Earth. They are doing the same thing as the water in a northern hemisphere bathtub and for the same reason. They are, in most part, not vertical cycles with surface water flowing north and sea floor water flowing south so any theory based on a disturbed flow due to lower salinity from ice sheet melt water is a theory that ignores the primary determinants of current flow, the rotation of the earth.
The theory of increased salinity in the Gulf Stream/Nth Atlantic Current due to evaporation ignores the fact that precipitation also takes place in the same regions. Ocean salinity maps indicate that highest salinity is actually in the middle of the North Atlantic (Sargasso Sea with high air pressure and low rainfall), not in the northern regions.
The volume of water in the Gulf Stream/Nth Atlantic Current is of such magnitude that a complete melt of the Greenland Ice Sheet over a period of only 100 years, contracting North at 27km/year, would dissipate the fresh water to such an extent that salinity levels would only drop from 3.5% to 3.45%. This variation is well within the normal range of ocean salinity levels. To suggest that a minor change in the chemical composition of such a large body of water could override the influence of factors of such magnitude as the rotation of the Earth, itself, is pure fantasy.
Consequently, we must conclude that the Pentagon was rather charitable in describing the Atlantic Conveyor/Ice Age scenario as an extreme scenario and very low probability event. It is, in fact, a highly improbable event that not only extrapolates known effects to improbable extremes but also excludes mitigating factors that are of thousands of orders of magnitude greater.
I am not endorsing Mott’s conclusions, but posting them for general discussion.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Which reminds me, I have to find that reference on ocean circulation – but not enough time at the moment – except that the author suggested that existing ocean circulation is an aberration. I’ll post the whole comment on my crazyworld blog after Xmas.
Incidentally Wikipedia is not a good source of information – its much like Newton and Leibnitz writing an article on the differential calculus and then having the 3 Stooges edit it before it gets posted on Wikipedia. There is a reason why the political left favour it.
Ian – perhaps you should read some of these
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v378/n6553/abs/378145a0.html
http://www.springerlink.com/(sgnupqfpfhcoen45dzsi5gub)/app/home/contribution.asp?referrer=parent&backto=issue,1,8;journal,40,101;linkingpublicationresults,1:100247,1
http://www.nature.com/nature/journal/v390/n6656/abs/390154a0_fs.html
http://www.nature.com/nature/journal/v415/n6874/abs/415863a.html
http://www.nature.com/nature/journal/v399/n6736/abs/399572a0_fs.html
If you can get the articles themselves then so much the better however to abstracts speak volumes.
BTW Google Scholar returned 5980 hits on the The “Atlantic Thermohaline Circulation”
Ender, I checked them all and can see nothing of particular relevance to this discussion. They all relate to the sensitivity of models, and model is a synonym for speculation. The test of a model is in its relevance to observable fact an on this question very little is provided by these urls.
The key fact remains that we are being told that these massive water movements are driven by density changes caused by increased salinity which causes the northern waters to sink.
That initial salinity increase that is supposedly driving the system at present is not observable.
The salinity reduction from melt water that is predicted in the models as driving a change in circulation is well within the range of variation in salinity that is already found in oceans all over the world.
And the volumes of meltwater under all plausible scenarios of ice sheet reduction are insufficient to produce any variation from normal ocean salinity levels.
It is not good enough for you to simply list a bunch of urls that other readers may assume to refute an argument without actually checking.
We are talking about known volumes of sheet ice, known volumes of ocean current, known evaporation rates and known rainfall rates, and known saline percentages. And the assumptions in these models simply do not stack up to even amateur scrutiny.
The url for ocean salinity in my post above should read http://www.windows.ucar.edu/tour/link=/earth/water/salinity.htm This includes a map of ocean salinity which also makes very clear that the largest body of less saline water in the North Atlantic is the Gulf of St Laurence.
Surface ocean currents are generally wind driven and develop their typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere due to the coriolis effect.
Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation, also known as the ocean’s conveyor belt, refers to the deep ocean density-driven ocean basin currents.
There is a significant body of paleographic evidence that that conveyor has slowed or stopped in the past – ice core correlations and studies of formanifera.
http://www.uvm.edu/~pbierman/classes/gradsem/1998/granab.html
Current studies in deepwater formation areas have found rapid declines in salinity.
Also it’s worth pondering that despite the rotation of the Earth we have a phenomenon called El Nino which causes worldwide circulation changes, changes in sea level height, depression of the thermocline, sea level temperature anomalies over vast areas and movement of the Walker circulation. How can it be ?
Ian – what it was meant to convey that all these researchers that work on this, sail in ships measuring ocean currents etc and construct sophisticated GCM models are all wrong and you are right?
I did make one mistake. I googled Atlantic Thermohaline Circulation to get 8000 hits I should have googled “Atlantic Thermohaline Circulation”. This better search returned 1180 results including this one http://www.nature.com/nature/journal/v428/n6985/abs/nature02494.html
“The Atlantic meridional overturning circulation is widely believed to affect climate. Changes in ocean circulation have been inferred from records of the deep water chemical composition derived from sedimentary nutrient proxies1, but their impact on climate is difficult to assess because such reconstructions provide insufficient constraints on the rate of overturning2. Here we report measurements of 231Pa/230Th, a kinematic proxy for the meridional overturning circulation, in a sediment core from the subtropical North Atlantic Ocean. We find that the meridional overturning was nearly, or completely, eliminated during the coldest deglacial interval in the North Atlantic region, beginning with the catastrophic iceberg discharge Heinrich event H1, 17,500 yr ago, and declined sharply but briefly into the Younger Dryas cold event, about 12,700 yr ago. Following these cold events, the 231Pa/230Th record indicates that rapid accelerations of the meridional overturning circulation were concurrent with the two strongest regional warming events during deglaciation. These results confirm the significance of variations in the rate of the Atlantic meridional overturning circulation for abrupt climate changes.”
Implicit in this is that salinity changes do change the strength of the current and it does fluctuate. If it was primarily driven by the Earths rotation as you seem to think how does is vary? The Earths rotation is gradually slowing however it does not change enough to account for the observed changes in the Atlantic circulation.
Let’s talk about El Nino/La Nina (warm/cold) ENSO events. These are intradecadal analogues of the 50-70 year cyclic variation in the upwelling-quantity of cold deep water in the equatorial eastern Pacific – which is a major driver of global climate (second only to variable solar eruptive activity). The last increase in upwelling was in the mid 1940s leading to 3 decades of gentle global cooling. This was abruptly reversed by the Great Pacific Climate Shift of 1976/7 – the most prominent climatic event of the 20th Century. These reversals coincide with inflection points in cyclic length-of-day (LOD) change, which coincide in turn with zero phases in the solar torque cycle.
Now look at the abrupt end of the great 1997/8 El Nino and the increased upwelling which brought back La Nina. At an equatorial buoy (125 degrees W), Pacific sea-surface temperature fell some 6 degrees C in the month of May ’88. The normal seasonal interchange of angular momentum, between stony Earth and mobile overcoat of water/air, is about one millisecond in LOD terms. In 1998 it doubled.
It is likely that extra-terrestrial (ultimately, planetary) influences not only drive longer-term changes in oceanic heat transportation, but are also a major influence at shorter terms. A friend tells me of unusual planetary conjunctions in May 1998. It may be coincidence – of course. We don’t know. But I think this is much more plausible than humans causing major changes to oceanic circulation.
Fosbob – tell us some more about the solar torque cycle.
And how does one measure the change in angular momentum. More info please.
Fosbob,
the planetary conjunctions of 1998 make sense to the plasma cosmologists – they the view earth as but a charged sphere in an interconnected electrical system, as are the rest of the planets andbodies in the solar system.
Gidday Jennifer,
Your readers will find some of FosBobs online papers at;
http://www.warwickhughes.com/foster/
I suggest “Climate-change science: duel of the hypotheses”, 31, December, 2000., as one place to start.
I see that some of my bottom of page return links do not work so just use your “Back” button. I need to do a bit of editing of pages that date from a server now gone to that network in the sky.
On my 19C icebergs page I have the length of day graphic from the Sharp / Goodridge LOD data going back over 300 years.
http://www.warwickhughes.com/climate/Iceberg.htm
My Blog has two entries relating historical facts from polar explorations which both suggest recent polar sea ice extents may not be so different from conditions a century ago.
http://www.warwickhughes.com/blog/
4 December, “Antarctic sea ice extent, South Sandwich Islands”,
and
11 December, “Little net change in Arctic sea ice extent in 110 years ?”
Best wishes,
Warwick Hughes
Warwick – we should not forget for the people that do not read you blog that Steve Bloom posted this comment. I have grave problems with one data point being used to prove a point.
This is what Steve Bloom said:
“Loius, the reference is to two separate problems in the Coolwire 13 article, a) the temp data and b) the sea ice data. Sorry if I didn’t make that clear.
John A., I don’t understand how your first response relates to the point I was making, but as long as we’re on the subject I have read the methodology used by GISS to come up with their temp numbers, and it appears to deal nicely with any potential urban/suburban issues. Do you have any specific problems with it? Before you ask, I’m not in a position to have the same discussion about the other data sets since I frankly don’t have the time to look at everything in the field. Regarding the critique of Coolwire 13, William’s analysis of the temp data issue stands for itself. You really should read it.
To expand briefly about my point on the sea ice extent, there are two data sets maintained, one by NSIDC and the other by UIUC. While based on the same raw satellite data, they use very different metrics for deciding whether a given satellite pixel has sea ice or not. NSIDC states their metric on their site and UIUC does not, but a quick comparison of contemporaneous sea ice extent graphics on the two sites makes it apparent that the metrics are quite different. This is fair enough as far as it goes, since there’s nothing intrinsically more valid about using, e.g., 10% versus 15% coverage to determine whether a given pixel has sea ice or not. Of course these different metrics result in similar but not identical anomalies, the graphs of which are also available on each site.
Another consequence is that the two methodologies will sometimes show different record years, which is what happened this year when NSIDC showed a record and UIUC did not. In any event, the media coverage in September was about the new record set by the NSIDC data, but Willis used the UIUC data to refute it. It was only by a very unlikely coincidence that I happened to know about the difference in metrics. There was obviously some sort of discussion to be had contrasting and comparing the two data sets and talking about the overall trend, but that wouldn’t have been nearly as exciting as accusing the NSIDC scientists of being alarmists or (by implication) liars.”
Ian – “The North Atlantic currents are horizontal cycles that flow in a clockwise direction due to the rotation of the Earth. They are doing the same thing as the water in a northern hemisphere bathtub and for the same reason.”
I have not seen a response to my question that if the above statment is true then how does the current change in flow if the rotation of the Earth is constant.
Gosh 8000 google sites. Does that mean that if there are 10,000 porn sites then porn must be a greater “truth” than thermohaline circulation. My post poses a few simple questions that need to be answered. They are;
Is the total supply of fresh water from Greenland ice melt sufficient to significantly alter the salinity (and hence density) of the total volume of sea water circulating through the area claimed to drive the cycle? No.
Is there even the very early traces of freshening of sea water in the North Atlantic? No.
Are there other places where freshening of sea water is more significant? Yes.
Does the model calculate the volume of circulating water or does it assume a fixed, static volume?
If a partial melt of the ice sheet reduces the speed of the cycle and thereby cools the Northern Atlantic climate then why would the ice melt continue to the point where it stops altogether?
Someone familiar with all these models should provide me with the assumed reduced salinity threshhold at which this combined sea and fresh water stops descending and thereby supposedly stops the cycle. And they can explain why they chose that number. And with that information we can then calculate exactly how fast the ice sheet would need to melt to produce that outcome.
My suspicion is that they have assumed the cycle has stopped before the actual cause takes effect.
Any other response is obfuscation or political spin. Does this particular scientific emperor have clothes or not?
Ender, the awitness.org/ url mentioned in my post above points out that the younger Dryas was in the middle of a period of glaciation. It cannot be used as an example of triggering a new or mini ice age.
Phil, the El Nino/La Nina upwelling is part of a thermohaline cycle but it is exactly that, a cycle of changes within a range of variation. And this range of variation interacts with surface currents to produce climatic cycles. The so-called Atlantic Conveyor theory speculates on a total disruption to that cycle based on an assumption that these surface currents either do not exist or play no part climate cycles.
Thank you Warwick Hughes and Louis Hissink for your support. Phil Done has two questions. I am outside my area of expertise here (I am a palaeo-climatologist, not an astronomer) but that has never stopped me before – why should it now?
Question 1. “Tell us some more about the solar torque cycle.” The Sun and the giant outer planets orbit the centre of mass of the solar system (boring Earth just orbits the Sun). Most of the angular momentum of the system is held by those outer giants, and their combined orbits apply a variable torque to the Sun. It is rate of change of applied torque which drives the Sun’s own irregular orbit, and also controls the widely-variable quantity of magnetised plasma ejected from the Sun into the solar wind.
Crucially, planetary motions, and hence solar eruptive activity, can be calculated. If the Sun keeps playing by the rules, detectable global cooling should be here by the end of this decade; and the next Little Ice Age cold period will be developed by 2030. This is within the planning horizon of responsiblle governments. How will they keep their people warm and fed during the Landscheidt Minimum? Enough! Question 2 will have to wait.
Ian – I agree there is a lot of unknowns – so do the modellers. But what do you make of the paleo evidence on the issue.
And I would dispute that the El Nino phenomenon is “cyclical” – not just nit-picking. It can “occur” but what causes it and and no particular cycle (well so it appears from the stats /evidence thus far). Reason I am bringing this aspect into the discussion is simply to say that large scale reversals in circulations can occur and do occur.
The paleo evidence seems to indicate the Atlantic climate is more variable than we might think and that the conveyor appears to have shut off in the past from deductions made of that evidence.
Ian – I am not sure that if you google google scholar with porn that you would get 1000 hits. Though you might get some because socialogical studies of pornography and society.
I searched google scholar which is a search of the scientific literature with that exact term in them. It indicates that there is a lot of research going on and you simplistic dismissal of the saline/temp gradient powering of the current is at best against most current scientific opinion. This of course does not make it wrong. However I did ask a specific question as it is a crucial, to me, test of your idea.
From a previous post I found this in an abstract “Changes in ocean circulation have been inferred from records of the deep water chemical composition derived from sedimentary nutrient proxies1”
It would seem that this current has changed in the past – how do you reconcile this with the fact that the Earths rotation has been approx constant over this same time scale?
Interesting reading on salinity levels and conveyor
http://www.realclimate.org/index.php?cat=19
Saltier or not?
Filed under: Climate Science Arctic and Antarctic Oceans— group @ 1:43 pm – ()
In a recent (of Sept. 16, 2005) publication in Science, Hatun et al. find that record-high salinities have been observed over the past decade in the region where water from the Atlantic flows into the northern oceans. They combine an analysis of observations with simulations using an ocean model, concluding that the salinity of the inflow to the northern oceans is controlled by ocean dynamics and the circulation in the sub-polar gyre. The observations by Hatun et al. may suggest that at the moment the warm and salty waters from the south are especially warm and salty.
In another publication paper in Science from June 17th 2005, on the other hand, Curry & Mauritzen conclude that as a whole the northern North Atlantic has become significantly fresher (less salty) in recent decades. The latter study was based entirely on observations (hydrographic data between Labrador and Europe in the past 50 years). The recent evidence for salinification provided by Hatun et al. has been interpreted by some as being inconsistent with the evidence for high-latitude North Atlantic freshening found in previous reports. So what is really happening? Is the salinity increasing or decreasing? And can the two recent Science studies be consistent with each other?
Ender, you appear to be assuming that I am disputing the existence of thermohaline circulation. Not so. But if surface melt water is being modelled in respect of its interaction with thermohaline circulation then the interaction with surface currents must also be modelled. It is not at all clear that they have been. As for the paleo records, that will have to wait until I get time to take a good look.
Phil, if El Nino is not a cycle then why do the climate records point to approximate 4,8,16 year cycles of rainfall events at our end?
Ian – “They are, in most part, not vertical cycles with surface water flowing north and sea floor water flowing south so any theory based on a disturbed flow due to lower salinity from ice sheet melt water is a theory that ignores the primary determinants of current flow, the rotation of the earth.”
This is what you said. As far as I can see you were disputing the existence of thermohaline circulation – sorry if I took it that way but it seemed pretty clear to me – hence the question.
Ian – not sure what “our end” means – Australia, where you live or ??
I am informed by El Nino experts that in general there are no cyclical patterns. You can say there are trends i.e. more El Ninos since 1976, wetter decades like the 50s and 70s, but that’s about it. {also Google Rob Allan, El Nino, CSIRO.} ANd then of course no two El Ninos are alike !? in terms of rainfall results.
Experienced climatologists worry about trends as you can easily have yourself on statistically speaking with our relatively short 100 year or so record. This of course has been the big trap with sunspot correlations. Fourier analysis will show that there are decadal and multi-decadal bumps. But you will arguments that it’s just red noise and not a signal.
To make a claim you need a good quantitative statistical argument, a plausible meteorological physical mechanism or driver, and get some future predictions right. And you have to get excited about as many as you get wrong as you get right. And survive publishing.
But don’t let that deter you (seriously!).
First thing to do is let someone who knows stats look at your stats argument.
Antartic Ice, I seem to remember someone did an analysis of sea ice extent from whaling ship records, does any one have details?. From memory it seems that antartic sea ice expands or stays constant in some areas while there are large decreases in other areas. The records of single explorers in the artic or antartic are likely to be difficult to interperate without understanding the larger spatial pattens.
Thanks Ender, I concede that the statement should have said something more like;
Given the volume and velocity of all currents operating in the area, vertical thermohaline cycles are not the dominant feature.
It also seem a little unrealistic to suggest that it is purely a saline dependent heightened density that makes a vertical column of water descend for only 4km, but with such power that it overcomes the drag induced by 5000km of ocean floor. This descending water column would certainly not be anywhere near the 3.6km/hour of the Gulf Stream. And it certainly would not be of such magnitude as to create a vacuum that would suck the Gulf Stream into it at a greater speed than the claimed active force.
It would seem far more likely that the descent of North Atlantic water is not based on a salinity/density excess but, rather, the simple fact that when a warm body of liquid or gas meets a cold body then the warm body will flow over while the cold flows under. It is a simple temperature based density excess.
And that is basic fluid dynamics. The northern water is, and will remain, colder than the Gulf Stream for the simple reason that it is from a Latitude that is less condusive to absorbing heat from the sun.
And on that matter we should ask, at what minimum temperature variance would a change in salinity/density override the normal stratification of warm over cold water? And is that minimum variance present in the North Atlantic, or likely to be present, given that the shape of the Earth itself can be assumed to be constant?
Thank you for testing this, Ender & Phil, but the more we look at it the more unrealistic the conveyor collapse theory becomes.
Ian – a couple of issues – the paleo evidence seems to support the conveyor stopping in the past. Othwerwise what is happening – alternative hypothesis? The debate stems from the paleo evidence combined with ice core evidence of rapid climate shifts.
You’re re-writing a fair bit of physical oceanography on the back of an envelope (and that’s not an insult – simply a great number of minds have studied the system. I agree the numbers seem large but it’s easy to be wrong on this stuff if you’re not well briefed on all the fluxes.
Other equivalent latitudes around the world are much colder so Britain owes it warmer climate to the Gulf stream.
Other major planet scale inversions do occur – El Nino for example. Why do these events defeat the predominant physics then and make the spectacular global changes we see? Why the does the circumpolar vortex change ?
Do you mean, Phil, that the world intellectual community has not been hanging on every word of this discourse? I guess I was misinformed. Seriously, my understanding is that most of the paleo record events, like the younger dryas, took place in periods of glaciation and much lower sea levels. And in the North Atlantic that means an exposed North Sea floor, much shallower floor south of Iceland and an interupted surface flow up the Norwegian Coast and down the Greenland Coast because of expanded ice sheets. This is not relevant to this integlacial conveyer collapse theory.
Ian – you may be interested in this account. Not a journal reference of course.
http://www.zinkle.com/p/articles/mi_m1511/is_n12_v17/ai_18938018?pi=znk
Interesting, Phil, it seems the author can’t decide whether he is writing science or the sequel to Lord of the Rings. Armies marching along the sea floor etc, I was expecting a cutaway to Frodo and Bilbo any moment. The nearest thing to a fact was a volume of 80 amazons.
But what it does highlight is the fact that this vast current is suposedly being driven by a comparatively mild force. This mild sinking of salt water in the north atlantic is assumed to be driving a cycle that includes all the force, volume and velocity of the southern ocean.
Prove me wrong if you will, but logic would suggest that the most dynamic part of a cycle is the portion actually doing the work.
And this brings us back to this assumed accumulated salt load in the north atlantic. The original analysis in my post dealt with an assumed absence of rainfall onto the gulf stream. But if precipitation is assumed to be only 50% of evaporation then the salinity changes will be even less significant. And if we add the very clearly mapped influence of fresher water from the Gulf of St Laurence as it drains the excess of the Great Lakes, then this whole, “heavy with salt” argument is getting very thin indeed. In fact, all the fresh water runoff from all the US Atlantic sea board rivers would ultimately be incorporated into this assumed salty current. And that is why the salinity maps don’t show it as being as salty as the mid latitude Sargasso sea.