Author of its Own Demise – musings on the AMO

Guest essay by Caleb Shaw

I once had a very good science teacher who I fear I made wild, not so much by causing small explosions in the back of his classroom, (which I think he secretly approved of,) as with my failures in math. He simply couldn’t understand how a seemingly smart person who had, as he put it, “uncanny powers of observation,” could be such an imbecile when it came to the most rudimentary arithmetic.

The answer was simple: I was fated to be an English major, and to experience the joy of studying Shakespeare, and then the chagrin of learning that makes you little more than a charming ditch digger, who can make other ditch diggers laugh by picking up a large stone from a trench’s bottom, peering at it fiercely, and saying, “Alas, poor Yorick; I knew him, Horatio: A fellow of infinite jest…” (You might think ditch-diggers wouldn’t know that quote, but a surprising number do, considering most are English majors.)

After years of this indignity my “uncanny powers of observation” kicked in, and I recognized the difference between hard work and hardly working, and I became successful in a small way, raising five children, none of whom are English majors. My youngest is studying to be an engineer, and he comes home from college to educate me about things English majors don’t have a clue about.

Don’t get me wrong; English majors aren’t totally stupid, and I do have “uncanny powers of observation,” after all. However you can’t observe what you can’t see, and engineering students can see things that are invisible to me.

For example, the other day I was relaxing, but my uncanny powers of observation were watching the pendulum of a clock, and I got to wondering what happened to the momentum that was going one way when the pendulum stopped going that way and started going the other. So I called my engineer son, and asked him. He smiled indulgently and explained it, talking about this stuff the momentum ran into called, “Acceleration due to gravity.”

I squinted at the clock real hard, but try as I might I simply couldn’t see that acceleration-due-to-gravity stuff he was talking about. I fear we English majors are colorblind and tone deaf, in this respect. And I humbly bow to engineers, who can see things I can’t.

However, before you engineers get too puffed up, I need to remind you I can see some things you can’t see, as well. You are occasionally colorblind and tone deaf in your own way, as was proven by the engineers who constructed “Galloping Gertie.”

Therefore it is likely for the best if we help each other out, when we become aware of each other’s handicaps. And we should be very thankful we aren’t as bad as some (who shall remain nameless) are so egotistically enamored of power, money and fame that they are blind to both what Engineers see and what English majors see.

That being said, I now require the help of some engineers regarding something my “uncanny powers of observation” have noticed about sea ice, and the lack of it.

I’ve noticed, (talking to fishermen and looking at old records,) that a huge change occurs in the North Atlantic every thirty years or so. You don’t have to be particularly smart to notice it. After all, the first to notice are the plankton, and, (while a psychologist in Australia who shall remain nameless has yet to measure the IQ of plankton,) I figure plankton study neither Shakespeare nor acceleration-due-to-gravity. Second to notice are the slightly smarter fish, first the small fry and then the larger predators. Soon after come the gulls, followed by the extremely intelligent fishermen, who are darn secretive about where the fish have gone. However, after twelve beers, they may become less secretive, even to a lubber like me, if I’m buying. So even I can learn the fact the ocean can abruptly become much warmer to the north, or just as abruptly chill. In fact I knew this forty years ago, when I lived on the coast of Maine, back before people used terms such as, “Atlantic Multidecadal Oscillation.” (AMO)

(What is really odd is that there are some people who never catch on, and deny past warming-events ever happened. Perhaps they burn their history books, and perhaps it is best they remain nameless.)

The more I watch this AMO the more my “uncanny power of observation” sees stuff, and the more I know I need engineers. I see a pendulum going one way, coming to a dead stop, and then going the other, but own up to a gaping hole in my knowledge of the mechanical reasons.

Because I am able to confess my ignorance without fear of losing my tenure or grants, (because I’m no professor,) I’ve been able to learn some things about fluid dynamics I didn’t already know. Among other things, I’ve learned fresh water behaves very differently from salt water.

In the case of fresh water, when sub-freezing air blows over water, water colder than thirty-five rises to the top, with the coldest water highest, and it is therefore easy for the ice to form. However, in the case of salt water, the colder water always sinks.

Selah. (Pause, and think of that.)

What this means is that for any ice to form in the Arctic Sea, theoretically you would have to cool the water to freezing all the way to the bottom, because warmer water from below would constantly be rising and replacing the colder water at the surface from below, as the cooled surface water constantly sank, until the entire column of water was at the freezing point of salt water.

To heck with that theory. Obviously the surface freezes before the water below. Even an English major can see that.

One reason the surface freezes despite the fact cooled surface water sinks has nothing to do with fluid dynamics, so I likely should exclude it. However, as it includes the eyewitness accounts of fishermen, and because I am an English major, I can’t resist.

It involves a solid that floats on water, called ice. Fishermen who dare the north have a dread of this solid, for freezing spray can make the top of their boat heavier than the bottom, in which case the keel points up, and they are dead. Despite this danger, they are lured north because the price of fish goes up, when it is hardest to get them. Therefore, at the very limits of water and ice, they see some uncanny things.

One uncanny thing is witnessing snowflakes falling onto sea water, and, because snowflakes are freshwater and melt at 32, and because the seawater is salty and doesn’t freeze until below 30 and is colder than the snowflakes, the falling flakes don’t melt when they hit the sea, and can cover the sea with a white dust, and occasionally even accumulate several inches deep.

But now we are talking solids, and that is illegal in fluid dynamics. It ruins the system where colder things sink and warmer things rise. Of course solid H2O will float on liquid H2O. Then, unless it becomes liquid and melts, even if it is small as a snowflake or speck of frozen spray, it has the capacity to grow.

If the wind whistling above that solid floating snowflake is significantly below freezing, the upper side of that snowflake will be cooled below freezing, and the bottom will act as a seed crystal for further freezing and expansion of ice, but, I reiterate, this is cheating. It involves solids, not fluids. So, even though this is a reality that happens, let us give these solids a cold shoulder and return to the purity of fluids and nothing but fluids.

At this point a second ambiguity appears, involving the fact colder water can at times float atop warmer water, because water does not merely stratify according to temperature, but also according to salinity. Salty water sinks below fresh water, just as cold water sinks below warm water. Things would be easy, if salty water was always cold and fresh water was always warm. However reality is seldom that easy. That darn Gulf Stream comes north, both salty and warm. Its salt wants to sink while its warmth wants to rise. What is a poor current to do?

Fortunately the Gulf Stream has an IQ of zero, (as far as I know,) and doesn’t have to think about such matters. It just obeys laws of fluid dynamics, and therefore can do things that I, with an IQ slightly above zero, cannot figure out.

The Gulf Stream is so warm that, despite being much saltier than northern waters, it rides above those waters as it branches and splits into various tendrils invading northern waters. However at some point the northern winds so chill those surface waters that the heat grows less and less able to trump the salinity, until finally it cannot stay on top.

It is at this point I’d like to propose an English major’s theory about a major difference between the warm AMO and the cold AMO.

In the case where the warm AMO is replacing the cold AMO, the tendrils of the Gulf Stream are invading an ice-covered sea. The water is quiet and still, and neatly stratified into organized layers, according to salinity and temperature. It’s a bureaucrat’s dream, a clamped-down situation never troubled by storm. And in that stratified stillness the Gulf-stream tendrils can dive a little down, yet still penetrate hundreds of miles north, warmer than the ice above. Think of it as a shuffled card sliding beneath another card. As the warm AMO continues, warm card after warm card slides into the nice, neat deck under the arctic ice cap, and nice, neat diagrams can be drawn of this extremely stratified situation, involving the thermocline and pycnocline and a “freshwater lens” atop the arctic sea. The only problem is that, with all these warm cards being slid in underneath, the ice atop the situation, which has been keeping the situation so nice and still and stratified, melts away.

We see satellite pictures of the ice-covered sea and watch the ice expand and shrink every year, but we cannot see pictures of changes to the water column beneath, especially when the ice makes it difficult to lower and raise instruments that measure salinity and temperature. (Scientists have devised some wonderful new gadgets, including one that hangs from a cable under a buoy sitting atop ice, and runs up and down the dangling cable collecting data from various depths, and they have managed to find the funding that allows them to deploy these gadgets despite the risk of meeting 1600 pound bears, however the data remains very sparse, and so recent it can’t show 60-year-cycles.)

What I would like to propose is that a major change occurs to several hundred feet of the water column’s top. Where it was nicely layered like cards, storms make a mess and it becomes a bureaucrat’s nightmare. The cards are not merely reshuffled, (unless you shuffle by playing 52-pick-up.) The stratification in nice, neat terms of salinity and temperature simply ceases to be.

I think we may have seen an example of this during the big summer gale of 2012. At the start there still remained warmer-but-saltier water down below, but, as the storm raged, the waters were disturbed down hundreds of feet, and warmer, saltier waters were brought up and into contact with ice, and amazing amounts of sea ice melted. However the results of that storm were twofold: As well as no ice above, there was no longer warmer and saltier water down below.

The following summer’s gales of 2013 also disturbed waters down hundreds of feet, but the ice up at the surface didn’t melt. Hmm. English major noticing a difference, here.

The simplest explanation is that the 2012 gale mixed the water like a spoon stirring ice water. After all, the word “stir” has the same root as “storm,” (which means absolutely nothing, except that I am an English Major.) The stirring melted ice, and the melting of all the ice chilled the water, and in 2013 the sea still remembered that chill, and was less able to melt ice. (Cooler water might also explain the lower temperatures noted in the DMI temperatures-north-of-80-degrees graph, though the Quiet Sun might have played a part as well.)

The problem I see with this idea is that the Gulf Stream doesn’t quit. It should have immediately started sliding new cards into the deck, recreating the stratification of waters in terms of salinity and temperature. Even if it took longer than a year to return to the status quo, we would fail to see the sort of dramatic change that can cause plankton, fish, gulls and fishermen to pack up and move for thirty years.

Therefore what I would like to propose is that, as soon as the waters are ice free and well-mixed by stirring storms, a radical change occurs in the ability of the northernmost tendrils of the Gulf Stream to penetrate northward. We can no longer use the analogy of the deck of cards, and need to turn to the analogy of a brick wall.

This is where I need engineers. I need someone to explain why a tendril of the Gulf Stream should abandon the status quo of shuffled cards, and abandon going over and under, and instead chose to go left or right.

There is a similar situation in the atmosphere, shown by the difference between a warm front and a cold front. The warm front slides up and over and creates layers, while the cold front plows and causes things to go left or right. However using that that analogy is cheating, because air is not a liquid.

It would be lovely to have a mechanical reason that explained why tendrils of the Gulf Stream stopped going hundreds of miles north under ice, and instead turned left or right hundreds of miles further south, forcing plankton, fish, gulls and fishermen to all pack up and move yet again. Of course, I am doing what politicians do, for I have an answer and am asking others to supply the science. However this is only wrong if your preconceived answer is dunderheaded, and you are paying scientists to fake data proving being dunderheaded isn’t dunderheaded. (I don’t have to worry about this, for I have no ability to bribe.) It isn’t wrong to throw a preconceived answer out as a trial balloon, to see if it lead or not, as long as you are a good sport, if you find out your idea was a Hindenburg.

What I like best about my proposal is that it explains the end of both phases of the AMO. If ice creates one sort of water column, and lack-of-ice creates another, then each phase could be creating a negative feedback which is its own undoing. Sea ice would allow the warmer waters to slide hundreds of miles further north, in the end melting the sea ice. Lack-of-ice would build a proverbial “brick wall,” diverting warm currents hundred of miles south, in the end encouraging the expansion of sea-ice. Each phase would then be the author of its own demise.