The Pacific Decadal Oscillation – Something to Think About?


First off, readers might be wondering, what is the Pacific Decadal Oscillation?  In 100 words or less:

The Pacific Decadal Oscillation is an alternating pattern of warm(er) or cold(er) surface water in the northern Pacific.  This condition stays in one “phase” (warm or cold) for 1 to 4 decades, then switches over and spends 1 to 4 decades in the opposite phase.  Compared to El Niño, it is like a slow boat to China.  It affects the climate all across the US and Europe.

And get this: It wasn’t even discovered until 1997, and then not even by a weatherman or climatologist, but by a biologist who discovered it while studying salmon catches.

In an online article I was reading from the spring of 2008, its authors made a seemingly innocuous and uncontestable assertion, one that most people would agree with.

Here is what the authors said:

The long term warming trend indicates the total energy in the Earth’s climate system is increasing. This is due to an energy imbalance – more energy is coming in than is going out (Hansen 2005).”

–  John Cross and John Cook “Is The Pacific Decadal Oscillation the Smoking Gun?” (2008)

And I was just about to accept it and go on, when I thought – wait a minute!  Not necessarily!

On the surface (that is a pun, which may become clear further down) it does sound correct, doesn’t it?  If our climate is to stay stable, with all that energy from the Sun coming in, then the outgoing heat has to be just enough to balance what is coming in.  That make perfect intuitive sense.

But is it really true?  I realized that that may not be the case at all, not in the limited way they say.  I thought of something right away that may suggest it isn’t true.  That statement assumes that the only possible sources for energy in this balance are what radiates in from off-planet (as they might say in science fiction) and then radiates back out, into space.

The climatologists have worked out all sorts of equations for what I used to call the albedo – the net energy balance of energy in versus energy out.  All of their assumptions are that the Earth itself is a passive player in the whole scheme, other than the ability of surface conditions to emit electromagnetic radiation – and its ability to store energy, primarily in the oceans.  All their derived constants and equations are predicated on nothing else being a part of the overall system.  They are all certain that they have identified them all, and that they now have a complete mechanism identified.

But is that true?  What if they have overlooked something?  They didn’t themselves, after all, even discover the PDO.  It was left there for all to see, and they missed it.*  Then, in 2001 another scientist – this time a climatologist – identified what is known now as the Atlantic Multi-decadal Oscillation (AMO).

Now, what would happen if it turns out somethings does a bit more than store some of the incoming energy from the Sun?  What if it sucks some of it out of the “In-Out balance,” possibly removing it for a long while from the interface zone between the ocean and atmosphere?  Would things get cold here for a while?  Yes.  (But “colder” may seem to us at the time to be normal…) And what if that reservoir sometimes oscillated the other way, bringing up that stored energy to the surface, so it can give it off for a while?  Would that tend to add energy to the system in the atmosphere, making it warmer for a while?  It would seem so.

We do have energy storage going on all the time, here on planet Earth, right now (but what I am proposing is a removal of that “extra” energy from the near-surface waters for a while, for some relatively period).  The oceans do sequester (store) heat energy all the time.  They absorb energy slowly, and they give it up slowly.  It is the depth of the water which makes this possible; shallow waters do it on a much quicker cycle time.  The oceans do this on a daily basis, moderating nighttime temperatures everywhere near the coasts, and less so inland.  Even large lakes do this.  I live near Chicago, where in the winter the phrase, “warmer by the lake” is well known.  In the summer, “cooler by the lake,” is a common refrain, too.  That is because  the water is a lot slower to warm up in the summertime, so the water tends to be not as hot as the land.  This is a seasonal thing, too, not just daily.  The lake temps tend to lag behind the air temps.  Overall, this tends to give the lake shore a more moderate climate than where I live, 30 miles away.

This idea I have is not being presented as a true reality, but as a speculation.  I’m in good part throwing it out there just to point out that we tend to accept some ideas because they seem plausible, and then we happily go back to what we were doing.  Though we try, sometimes there just might be options that we have missed.  Maybe.  But if some other possible mechanism crosses our minds, then it is incumbent on us to check them before we agree with unequivocal statements like the author makes in this article.

I actually strongly agree with the author’s title and central theme.  I do think the PDO is the smoking gun (but perhaps not the final word – see the ** note below).  But while he is pointing at the PDO as a smoking gun, I wonder if he is looking at all the ramifications of what that huge heat reservoir represents.  (I know he already is, but I believe he is looking at the reservoir as a relative constant; I am suggesting that the underlying process flips and flops from time to time, perhaps based on an overload of stored heat and then when the overload is fully released returning to its “deep sequestering phase.“)  The Pacific averages 13,000 feet deep – nearly half the height of Mount Everest.  Denver, the mile high city, is only about 40% as far from sea level as the bottom of the Pacific, on average.  That is a ridiculously large amount of water to store heat in.  So, there is a lot of energy it can store, certainly much more than it currently does.  The deep sea temperatures are studied, to be sure, but vast areas of deep sea have never been studied.  Currently they believe they understand it well enough.  And yet, the PDO gets its warm phase from somewhere, and especially so, so does ENSO.  Maybe it is not as “steady state” as is currently thought.

For your visual education, here is a model of the PDO:

…Think of this:  The climate charts we see, when we see Al Gore’s movie “An Inconvenient Truth,” or in documentaries on The Science Channel, or The Discover Network , or on Nova – all those graphs represent about TWO DEGREES Celsius, from top to bottom.   Those curves on a standard temperature graph would seem very nearly a flat line.  The vertical scale throws the peaks and valleys all out of proportion.  If zero were shown as the baseline, no people would pay any attention.  The zero in the graphs is actually about 15C (about 59F).  I  journalism class we were taught to be wary of the ways graphs are used, that by playing with what is shown, the impression can be manipulated.  Be aware that those people with their laser pointers and zoom-ins and pans are pointing to the last 20 years and making a big deal out of just the upper half of that graph – less than ONE degree C.  Those horizontal lines on the graphs represent only 0.1 or 0.2 degrees C.  And that is not even enough for us to notice when we go outside.  We barely register a full degree C, with our senses.  (I often wonder at the ability of climatologists to state with a straight face that 1C or 2C can take us into an ice age.)

The measurable heat differences depicted are actually quite small.  I often furrow my brow that such a small difference could have resulted in the Medieval Warm Period and the Little Ice Age.

So, what I am proposing that we think about is this:

Warming phases (and cooling, too) might just be a rearranging of the energy distribution process for a while.**

That is maybe an oversimplification, but is essentially all I am suggesting.  Something causes the PDO.  It is only an effect of something else going on.  But what is that something?

Maybe the PDO – which is an oscillation of temperatures (as measured at the sea surface), by its definition – is just us seeing the tail end of a process that sometimes absorbs more energy than it releases, and sometimes gives up more than it takes in.  As such, that underlying process also must be part of our overall equation.  If so, we cannot just look at the In-Out of the Sun and radiation from the surface and think we are seeing the entire equation.  That is what I am saying: there may be more to it than that.

Now, this is not one of those pigs flying situations.  It really could be that enough heat energy (to affect the overall atmospheric situation) is sequestered in the deeper ocean (such as the Northern Pacific), and that it only rises to the surface under certain conditions. Those conditions may be currents or wind patterns that change, for shorter or longer periods.  It may be some as yet undiscovered process. After all, ENSO and PDO and AMO were undiscovered not so very long ago.

El Niño/La Niña variations, from the 1997-1998 worst-case event (so far):

Complete speculation: It is even remotely possible that the heat of the El Niño (usually called ENSO*** now, to include the entire cycle of El Niño and La Niña) actually comes from undersea volcanoes or vents, though that doesn’t immediately seem to explain its cyclic history.  The ENSO heat flow is generally away from the extremely volcanic islands of Indonesia, so perhaps there are things going on that have not even been looked at (if you don’t look for it, one is much less likely to find it).  Since this paragraph is just complete speculation, I will add that the heat from undersea volcanic eruptions must add something to the system.  How much cannot be known, since we know so little about the deep sea.  It is likely that the vast majority of undersea eruptions and thermal vents are never even noticed.  But heat the water they must.  That they do so on a cyclic basis, though is not even worth speculating on – therefore this is not to be construed as suggesting they cause ENSO or the PDO.  But the heat they release may be accumulated over time, before causing El Niño events.

As I understand it, the El Nño phase of the ENSO is currently understood to be a change in the wind currents (although the currents, too, might actually be an effect, not a cause****). The heat signature (sensed by satellites) of ENSO represents a HUGE amount of heat energy that does not appear to come from anywhere. It doesn’t come directly from the Sun, so the best concept may be that the sequestered heat might be coming up from the abyss. Perhaps the prevailing currents from Peru normally push the warmer water down (I know, that seems counter-intuitive) or just back toward Malaysia.

But where else could the heat come from, if not from the Sun? (which is still the best bet, but may still be wrong.) And if it does not come from the Sun, then it is not part of the (relatively short term) albedo/energy In-Out balance that the author of the article asserts. At least not in any way we currently know of.  Look at the temperature gradient on those ENSO models (which I assume somewhat reflect the actuality).  Those temperature anomalies are not in tenths of degrees, but range up to 8 degrees C and more – and that is only in one direction!

Back to the climate, as it applies to the PDO especially, the heat energy under the ocean may well up for periods, bringing more heat energy to interact with the atmosphere.

This is all speculation. But I’ve been following the PDO since right around 2000, and wondered for quite a long time how long it would be before scientists were going to start to realize that climate theories and models that don’t include the PDO simply cannot possibly be correct.   (I think investigation of the PDO has actually been considerably hampered, because of the grant moneys so often going for research on AGW.)

The Pacific Ocean is the bull in the china shop, as far as climate goes. When the bull snorts, people get stung.  The Pacific is about 30.5% of the surface area of the planet – more than all the land area put together. It is fully FIFTEEN times as big as the United States. What happens out there, energy wise, in the Pacific, dwarfs everything else, excepting only the Sun. And then consider the 1/30th of 1% of CO2 in the atmosphere and the 5% or 2% of CO2 that humans create. How totally insignificant our activities are in comparison to the northern Pacific.  Even if we just consider the northern part as 1/3 of the overall Pacific, it is still five times bigger than the U.S. – 3 bigger than the old Soviet Union, and 1-1/2  times more than the entire Moon’s surface area.  Add to that the 2-1/2 mile average depth, and that is a lot of water.

The climate models upon which AGW were originally based were created in the early 1990s. This predated the discovery in 1997 of the PDO, so they could not have included the PDO. And if they don’t, those models were (and are still, I believe) fundamentally wrong, because they were missing a huge factor, the PDO. One would have to think that it will be a decade or three of four before we adequately understand the PDO well enough to even approximate it in the models.

These oscillations – ENSO and PDO – plus, the Atlantic Multidecadal Oscillation (AMO), must also lead us to look for other ones.  With the PDO in the northern Pacific and ENSO along the Equator, it is likely that a southern PDO (the SPDO? – one would hope not!)also exists, telling us that the three regions probably act as separate entities, though nominally interconnected.  There is an atmospheric parallel to this: I learned years ago that the air circulating in the northern and southern hemispheres has very little bleed-across; the equatorial convection which causes the Doldrums also acts as a curtain blocking almost all the air from coming across.

There might be a similar oscillation in the Southern Atlantic (the AMO is measured in the northern Atlantic), and possibly on in the Atlantic equatorial region, too, one that could have huge impact on our ability to understand Atlantic hurricanes.  The land masses that pinch in the Atlantic there may complicate that one beyond all recognition; El Niño studies should actually help clarify the Atlantic equatorial processes, since the relatively uncomplicated Pacific would make recognition of processes much simpler.  In addition, the Indian Ocean might also have an oscillation that has not been recognized as of yet.  When all these processes of oceanic heat movement and storage are more deeply understood (pun intended), then the picture of weather and climate will have that much more potential of being understood fully.

. . . . Steve

* Actually, not quite: In 2004 I had a personal email communication with Dr. George Taylor, who at the time was the Oregon State Climatologist, in which he said he had actually seen the pattern in the early 1990s, but ruefully admitted to having done no work to formalize his claim on it.  Dr Taylor is considered to be a climate skeptic, which at least in part seems to have cost him his position with the state of Oregon.

** If so, then our present understanding of climate needs to change.  More effort would need to be put into studying the oceans’ heat cycles.  We presently have an overall concept of them that did not – until 13 years ago – even know about this huge oscillation over 1/10th of the world’s surface area, with a heat reservoir 2-1/2 miles (4 km) deep.  Our understanding could literally be said to have been shallow.  And almost as literally, it could be said the PDO and ENSO are only the tip of the iceberg, since all we are measuring is the temperature at the very top few feet of that 4km.  What else  is going on down below?  Just as geographically we are as yet quite ignorant of what is down below, energy-wise we are even more in the dark.

** ENSO – El Niño Southern Oscillation – oscillation, because it alternates with La Niña, a very cool pattern.

**** The climate and weather, being always in flux, is acknowledged to be a terribly difficult thing to study.  There is no starting point, since everything affects everything.  It seems that the climatologists have arrived as the Sun’s input as being the starting point for everything, since it is something coming in from the outside, plus its energy input can be measured fairly readily in several different forms.  The assumption that the Earth is only a passive receiver of energy (barring volcanic events) seems normally to be true; I agree on that.  But since there are these oscillations that were not even known about until the last 13 years, perhaps the planet is a more active participant than has been heretofore imagined.

***** For this reason, I always wondered how fluorocarbons were supposed to get in large numbers from the industrial northern hemisphere to the south pole to cause an ozone hole.  One would think that if the fluorocarbons could make it that far, then so could the ozone that causes alerts in our northern cities, thus being able to replace the ozone over Antarctica.

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