Arctic Ice: The difference 100 years can make.

Global warming and its effect on the Arctic seems to be regarded as recent phenomena but sixty years ago scientists were already concerned about reports of loss of ice cover in the Arctic Ocean and a reduction in ice thickness.

Although there weren’t too many satellites available in 1916 to give a decent coverage of ice conditions, there were a few ships around. Here are the monthly charts for the summers of 1916 and 2016; make what you will of them.

June:
1916_06

arctic_160630_amsr2

 

July:
1916_07arctic_160731_amsr2

 

August:
1916_08arctic_160831_amsr2

 

Sources:

Charts for 1916 are from here: http://brunnur.vedur.is/pub/trausti/

The charts there are in the zip-files at the bottom of the page in either jpg or pdf.

Charts for 2016 are from: http://www.iup.uni-bremen.de:8084/amsr2/

 

Can the media be trusted?

OK, stop laughing. No, please, let’s have some order.

Andrea Leadsom is complaining that the Times has misquoted her. Well, no surprise there then but a revealed transcript is being taken by either side in the argument as evidence that (a) it’s a smear or (b) that it isn’t. I haven’t read it yet so will not pass judgement. Instead, I’ll go back to an occasion when the Times, with help from the BBC, tarnished the reputation of a Labour party member and possible future politician.

One evening, a couple of decades or so back, the BBC-tv news said they’d received a tape-recording, courtesy of the Times, of a Labour party candidate(?) expressing a desire to overthrow the system of government in this country. This is, as best as I can recall, what he said:

“Then I would throw the Royal Family, the judges, and the heads of the military into the Tower.”

This was all there was. Now, I don’t know about you, but there’s one word in the sentence that stuck out like a sore thumb when I heard it. I waited in vain to hear something in the rest of the bulletin regarding the context in which this statement was made. Nothing in later bulletins that evening or the next day or in the press picked up on the all-important word. Early next morning on the radio, there was a  brief interview with the accused in which clarification came, but I only heard that interview once and, as far as I’m aware, it was ignored forever afterwards.

Oh, didn’t I say what the word was? Do I need to? It’s obvious isn’t it? OK, perhaps it isn’t that obvious as the BBC didn’t spot it or they never would have been so gullible as to accept the doctored tape from the Times. Nor did any journalist I heard or read – bar perhaps one? – seem to have the required number of grey cells to spot it. What is the word?

“THEN”!

This vital word showed me immediately that no sense could be made of the extract without knowing what prompted the statement. It was in the brief interview the following morning that it came out that the condemned man had been taken part in a debate. He said that he had been arguing in favour of parliamentary democracy when he was asked, “What would you do if you became aware of a plot involving the Royal Family, the judiciary, and the military to overthrow the government?” He answered, “Then . . . ”

Thanks to the duplicitous actions of the Times, and the stupidity of the BBC and the rest of the media, this man was forever referred to as being someone who was intent on overthrowing parliamentary democracy in this country.

I’m ashamed to say that I can’t remember his name or what happened to him afterwards. If anyone recognises the event and can shed more light on it, I’d be grateful.

EU Referendum was a “clear result”. Or not.

Tory candidates for PM keep saying the EU Referendum gave a clear result for leaving the EU. Really? Here are the results expressed as a percentage of the total electorate:
Leave: 37.44%
Remain: 34.71%
‘Abstained’: 27.85%
As I understand it, under proposed Tory government legislation for Unions holding ballots for industrial action, this referendum would have failed as the ‘Leave’ vote was under 40%.

So, the candidates are saying this is a clear mandate for making the decision to leave the EU but would be insufficient for enabling a union to make the decision of calling out its members on strike. I guess they must view leaving the EU as a fairly trivial issue compared with a few hundred workers going on strike for a day.

Why have the English seasons got in synch?

Back in 1969, I attended a talk by N E Davis covering 100-year cycles he’d found in our local (English? UK?) seasonal temperatures. One thing that was apparent was that the cycles were out of synch with each other; the winter cycle looked to be just past its minimum whilst autumn was just passed the maximum – or would have been if the scorching heat of October 1969 hadn’t messed things up. From these cycles, he seemed fairly confident that there would be late springs for the next fifty years. That prediction started out OK in the early 70s but global warming threw a large spanner in the works.

The following graph of Central England Temperatures, which I’ve smoothed by using a 50-year running mean, shows this pattern of out-of-synch cycles though lengths seem to vary more than I expected from the talk. However, what is remarkable is the way that the anomalies have been in line with each other over the past fifty years or so.
Seasonal anomalies 50-yr

The next graph shows the range between the seasonal anomalies. The latest downward trend in this graph appears to start at the beginning of last century but, due to the 50-year averaging, this could mean the trend could have started in about 1925.
Seasonal anomalies 50-yr range

I confess that I have no idea why this has happened, whether it’s just that it was bound to happen sooner or later or whether global warming might be responsible but I’ve no idea what mechanism would be involved there. Perhaps the cycles, if they existed, were not all the same length and they’ve only recently coincided. I’m stumped.

CET data from Met Office Hadley Centre

Care of toenails

I read in the New Scientist a little while ago that scientists had discovered the best way to cut toenails in order to avoid them ingrowing.  As I recall, it involved cutting the nail in the shape of a perfect parabola. My first reaction was that who the hell can cut a nail to that accuracy. My second was that they were incompetent ignoramuses. Toenails should be cut straight across or even with a slight concave shape.

My mother taught me this method when I was a child and I’ve been following it ever since. She also did this until, as she got older, had increasing difficulty cutting them. She had to have a chiropodist visit to treat her toes. This ‘expert’ cut her toenails with a convex curve, more or less as you would with fingernails. Needless to say, she developed ingrowing toenails and had to have the nails on both big toes removed. How do these idiot practitioners get qualified? Presumable it’s a case of the blind leading the blind? That’s my guess after bad experiences with opticians.

Anyway, just recently I found in an old book of hers where she got the original advice. It may be old but it works. It comes from the Daily Herald Enquire Within published by Odhams Press Limited. I don’t know the date of publication but it does contain useful illustrations of the latest types of gas-masks so let’s say sometime in WWII.

Here’s a copy of the article:
Nails_treatment_2_400

Test

This is just a test of putting images from LibreOffice Calc in a blog. I’ve just copied a section of a spreadsheet page, pasted into GIMP and then exported it as a PNG image. Let’s see what it looks like. Fingers crossed!

ENSO

Looks OK so far. Let’s try a really wide one.
ENSO_wide

Wow! OK, can’t read it so click on it.

Bi-stable Nature of North Atlantic Ocean Currents

Why The Big Chill made me hot under the collar.

You probably have heard during the past dozen years of the “Ocean Conveyor” and how increased melting of Greenland glaciers could affect this “conveyor” in such a way that the Gulf Stream would stop, thus giving the UK the same climate as Alaska within the next twenty years, i.e by 2023. That is utter balderdash. The Gulf Stream can’t stop. Evidence shows that the clockwise circulation of warm water has not stopped once in at least the past 30,000 years. Having said that, I’ll explain later about how a sudden change in climate affecting NW Europe may occur soon due to the bi-stable nature of the North Atlantic current system.

So where did this misinformation come from? I first encountered it whilst watching the BBC-tv Horizon programme entitled The Big Chill on 13th November 2003; it was unlucky 13 for anyone unfortunate enough to watch it as they could well have been taken in by it. For the record, here is the transcript of the broadcast: http://www.bbc.co.uk/science/horizon/2003/bigchilltrans.shtml

Horizon had become a sensationalist programme, not really worth watching, long before this edition. However, in this case, it seemed to me that much of the blame could be laid at the door of the scientists themselves. Of course, this could all be due to the film-makers taking things out of context but it’s hard for me to believe that, given some of the claims made during the programme.

Prof Richard Alley found from Greenland ice cores that “temperatures could drop suddenly and catastrophically” and said that “This flabbergasted us, I think this flabbergasted a lot of people.” OK, count me as one of the unflabbergasted. Why? Because I’d discovered this over thirty years before the programme was first broadcast. How? By studying gases or heavy water in ice cores, foraminifera in cores from the ocean bed? No. I read it in a book. I confess it; I’m lazy and will always take the easy way out if I see one.

The book wot I read.

Unfortunately, I can’t remember the name of the book that I read in the late sixties. I think it was one that dealt with different types of ice and their properties. In one section, the author explained why ice was slippery and that it was not due to the commonly-held theory that pressure on the ice melted it and produced a lubricating layer of water. Instead, he explained how the molecular structure of the ice at its surface was responsible. I noticed an item in last year’s New Scientist that this has been discovered again.

In the book, the author explained how the current system in the North Atlantic is bi-stable, meaning that it has two stable states and can flip suddenly from one to the other. Once it has flipped, it will remain in the new state for a long time. He likened a bi-stable nature to that of a pencil standing on end; if no external force acts on it, it will remain in that position but, if nudged, it will fall onto its side. I’m not sure whether this is a perfect analogy for the North Atlantic as the force required to move the pencil from its new stable state to its original one is much less than that required to displace it in the first place. I suppose that could be true for the North Atlantic and that one current system only requires a little nudge to flip it but a larger force is required to tip it back.

Flip-flops explained.

The discovery related in the anonymous book was that the North Atlantic Drift (NAD) can suddenly switch from being a warm current breaking off from the Gulf Stream circulation to a cold one sourced by the Labrador Current. The author explained that these flips to a cold NAD were correlated to sudden changes to a cold climate in NW Europe. He did not know what caused the NAD to flip but thought it might be due to a slowing of the Gulf Stream, perhaps as a result of a weakening of the sub-tropical high.

The one good point about the Horizon programme was that a solution to the above problem seemed to have been provided, namely that of a weakening or cessation of the deep conveyor due to increased melting of the Greenland ice cap and consequent lowering of salinity.  This would then lead to the slowing of the Gulf Stream and the subsequent failure of the NAD to reach escape velocity and its replacement by an extension of the Labrador Current.

A light-bulb moment?

However, a couple of weeks ago, a doubt about all this suddenly popped into my mind. I didn’t really buy into the idea of the warm NAD suddenly  stopping due to a slowing of the Gulf Stream and, I suppose that deep down, I’d always had a nagging unease about it. Along with the doubt springing to mind, came a possible alternative explanation which, if true, would explain how the NAD can suddenly flip.

The chart below shows the present current circulation [tempted to write “current current” there] with a warm North Atlantic Drift (NAD) breaking off from the Gulf Stream circulation and passing by to the west of the UK, helping to keep the country relatively warm, considering the latitude.

Now, another problem I had with the Horizon programme was the location specified for the sinking of the warm water to provide the source for the conveyor. As I recall, the map showed the main warm water sink occurring to the south of Iceland but that went against all I’d learnt some thirty-five years earlier. As I recall it, there was one sink in the gyre NE of Iceland and another probable one, perhaps two, in gyre(s) north of Jan Mayen. The map in the Wikipedia article here  https://en.wikipedia.org/wiki/Thermohaline_circulation   although idealised, I think is a little closer to the mark although it shows a sink off Labrador as being for warm water. As I remember it, the main sink in that area is a cold-water one where the cold Labrador Current sinks below the Gulf Stream, as I’ve indicated on the following map.

NA Currents Warm_1.10

North Atlantic Ocean Currents, version 1.

Now, how do the sinks behave differently?

Who is the densest of them all?

For those east of Greenland and others further north, the warm water is more saline than the cold water. Although the temperature difference acts in the opposite way, making the density of the warm water somewhat less than it would have been without that difference, it’s still insufficient to make it lighter than the cold water so it sinks below it. There is also some mixing occurring in the gyres so heat and salt is exchanged and some cold water also sinks.

The situation off the Grand Banks is somewhat different. Here, the although the cold water of the Labrador Current  is less saline than the Gulf Stream, the temperature contrast is greater and is sufficient to make the warm water lighter than the cold, hence the Labrador Current largely sinks off the Banks beneath the Gulf Stream. Another consideration is that the Labrador Current has travelled a long way from its Greenland source and has its salinity level raised through an admixture with saltier currents.

There are several causes of ocean currents, including the wind, but the one I want to consider here are density currents. Where adjacent waters have different densities, the sea surface of that with the lower density is higher than the other. Thus water flows downhill from low density to high. However, the Coriolis effect takes hold and the water is turned to the right so that a current flows parallel to the density contours. In the case of the Gulf Stream, the strong current near the boundary with the cold, south-flowing extension of the Labrador Current is due mainly to the density component.

So what happens when the salinity of the Labrador Current decreases due to increased melt from Greenland’s icy mountains? I would expect the density component of the Gulf Stream to weaken as the density contrast weakens. But what else? Could the lowering in salinity of the Labrador current be sufficient to reverse the density contrast? I suspect this may be happening north of the Grand Banks where the temperature contrast is lower and hence makes a lower contribution to the density. It may be possible that the cold pool in the Atlantic is a sign that some Labrador water is now flowing over the warmer waters to the east.

NAD waving, but drowning?

If the change in salinity goes further and the density of the Labrador current becomes less than that of the Gulf Stream, the flip could occur where the old NAD sinks below the Labrador Current and then turns south to join the THC. Meanwhile, the Labrador Current sails eastwards on the surface, swapping places with the NAD. The map below is my idea as to how the new situation [well, not exactly new as it’s happened before] will look. I confess the route of the submarine NAD is pure guesswork and chosen mainly to make the map somewhat clearer.

NA Currents Cold_1.10

North Atlantic Ocean Currents, version 2.

Conclusions – at last!

I think my light-bulb moment a couple of weeks ago explains how the NAD can suddenly cease and a wholesale change in surface currents can occur, but then I would, wouldn’t I? The big problem is that I don’t have the data to calculate whether the theory is tenable; I leave that to the readers – if any.

Acknowledgements:

The one obvious thanks I have are to the author of the book I read so long ago. I can’t remember his name or the name of the book. I think he was an oceanographer at Woods Hole and that the book – a light blue soft-back – was published in the early sixties.

Those whose software I used to produce the maps may wish to remain anonymous and not be associated with the ham-fisted use I’ve made of their products. However, they are:

Maps generated from Marble: https://marble.kde.org/

My artwork [snort!] from Gimp: http://www.gimp.org/