Update: Since I posted this article Bob Tisdale, on WUWT, went a bit overboard in his flattery, comparing me favourably to some of the world's leading climate scientists. Click here for the article that made Perennially Puzzled Bob Tisdale laugh. It's quite short and to the point. This latest one below is more comprehensive but much, much longer. (As Bob knows, I'm not able to comment at WUWT even if I wanted to respond to his praise there.) A tip of the hat to William Connolley at Stoat.
PS I'm just a blogger who's interested in climate science. Don't be fooled by Bob's effusive compliments (archived here). I'm not in the same league as the climate scientists at realclimate.org or William Connolley.
Sou Sunday 12 January 2014 7:10 am AEDST
Yesterday Anthony Watts posted an article by Bob Tisdale (archived here). Apparently it's an excerpt from one of his books. Bob sees himself as something of a (self-taught) expert on El Niño Southern Oscillation (ENSO). He doesn't acknowledge the scientists who gave him what knowledge he has, but he does castigate them:
As long as the climate science community continues to treat ENSO as noise, they will make little progress in understanding the natural contribution to global warming, and it’s a sizeable contribution. We’ve discussed for years that the climate science community has failed to account for the “leftovers”, the residual warm water, from strong El Niños.
Nowhere does Bob explain what he means by his "leftovers" except for describing them as "residual warm water" from strong El Niños.
What gets me is that Bob Tisdale says that the scientists who taught him all he knows about ENSO "don't know nuffin'" about ENSO. And he gives them no thanks, not even an acknowledgement, although he got all the material for his "books" he's flogging (at a discount this week only!) from those same scientists. And they didn't charge him a penny. I admit he tweaked the bits where he decided to reject their science for his own purposes. He's got a reputation to maintain at WUWT as a fine upstanding greenhouse effect denier after all.
This article has grown - a lot. Click here to read the rest if you're on the home page.
Before going too much further, if you aren't familiar with the El Niño Southern Oscillation aka ENSO, here are a couple of basic descriptions:
- The three phases of ENSO - from the Australian Bureau of Meteorology, which is part of a longer set of articles on ENSO starting here (the menu is on the right hand side of the page).
- El Niño/Southern Oscillation (ENSO) Technical Discussion - NOAA
It's to do with sea surface temperatures and air pressure, the thermocline (the barrier between the deeper cold ocean and the mixed ocean layer closer to the sea surface), the east-west Pacific equatorial winds (the Walker Circulation). Plus the the massive "waves" - the eastward propagating Kelvin Waves and slower westward propagating Rossby Waves (which are described in the Columbia University article and in more detail here at ThinkQuest.org). These latter waves (Rossby waves) can also propagate north and south as they bounce off the land masses.
Below is an animation of the different phases of ENSO, showing the shift in the Walker Circulation and the temperature of the water in the equatorial Pacific, as shown on the BoM website. (I've modified the timing a tad so you can see it more clearly.)
When ENSO is neutral, there is an area of high pressure off the coast of South America (to the right of the above diagram) and an area of low pressure around Indonesia up above Australia (toward the left of the above diagram). That means the trade winds blow from east to west (from high pressure to low pressure).
In La Niña the warm seas build up in the west, the pressure differential increases, the trade winds (and Walker Circulation) strengthen. The Walker Circulation stretches right across the Pacific, and the thermocline in the eastern Pacific rises higher over a large area, bringing cooler water to the surface. The surface temperature of earth cools (or doesn't warm as much, given this is now happening against a background of global warming.)
In El Niño, trade winds are weaker. The Walker Circulation weakens and can even reverse in an intense El Nino. The sea surface temperature in the east is warmer than before (the thermocline drops and there is more warmer water in the mixed surface layer) and to the west it's cooler. The warmer water spreads right out over a much larger area of the ocean and the surface temperature of earth gets hotter (more heat is transferred from the ocean to the air). El Niño is also known as the discharge phase of ENSO, where the heat accumulated in the west of the Pacific is discharged to the air and, in the ocean, it is moved away from the equator toward the poles.
The main impact of ENSO events is felt in various parts of the world (differently) as variations in rainfall and temperature on land. That's why it's so important. It also affects fisheries. So ENSO events can cause heat waves, droughts and floods. They typically last several months but can continue for longer. They are regarded as inter-annual variations on the time-scale of weather rather than climate. (Contrast ENSO events with the Pacific Decadal Oscillation, which has a period of multiple decades.)
In my travels to find out more about this phenomenon, I came across a rather good book chapter: El Niño and Southern Oscillation (ENSO): A Review by Chunzai Wang, Clara Deser, Jin-Yi Yu, Pedro DiNezio and Amy Clement. It's recent, dated May 2012.
The Wang12 paper describes the various mechanistic models for ENSO as follows:
The theoretical explanations of ENSO can be loosely grouped into two frameworks. First, El Niño is one phase of a self-sustained, unstable, and naturally oscillatory mode of the coupled ocean-atmosphere system. Second, El Niño is a stable (or damped) mode triggered by or interacted with stochastic forcing or noise such as westerly wind bursts and Madden-Julian Oscillation events (e.g., Gebbie et al., 2007) and the tropical instability waves in the eastern Pacific Ocean (e.g., An, 2008).
The paper goes on to describe four conceptual oscillator models for ENSO:
- The delayed oscillator - Suarez and Schopf (1988) Click here for a link to a good description of the delayed-oscillator model.
- The recharge oscillator - Wyrtki (1975, 1985)
- The western Pacific oscillator - various
- The advective-reflective oscillator - Picaut et al. (1997)
No, Bob Tisdale - It's not the Sun!
Since ENSO is central to Bob's "the world warms by magic" hypothesis, I decided to examine his description of ENSO to see if it has any major departures from the science he bases it on. Bob's version is similar to the scientific version up to a point.
|Source: Box TS-5 Figure 1 IPCC AR5 WG1|
Southern Oscillation Index and Pressure Differences
One other difference is that Bob doesn't refer to pressure, he refers to temperature differences instead. (On the WUWT page, the word "pressure" appears only once, and that's in a comment by FrankK.) However Bob does describe the effect of temperature (despite not using the word "pressure") and how this creates a gradient of high to low pressure east to west that drives the trade winds.
Temperature and pressure are related of course, so one could argue that it's not a major point of difference. The reason I mention it is because these days one of the main ways of monitoring ENSO is by looking at pressure difference. The Southern Oscillation Index, which is calculated using the Mean Sea Level Pressure pressure differences between Tahiti and Darwin, is used to get an indication of whether there is an ENSO event and if so how strong it is. Sustained positive values of the SOI above +8 are typical of a La Niña episode and sustained negative values below -8 are typical of an El Niño.
Complicating things further (or simplifying things, depending on your perspective) are the different Niño Regions. The BoM website monitors three indices in terms of sea surface temperature, Niño Regions 3, 3.4 and 4. But there's more. As described on this Columbia University web page:
Indices based on sea surface temperature (or, more often, its departure from the long-term average) are those obtained by simply taking the average value over some specified region of the ocean. There are several regions of the tropical Pacific Ocean that have been highlighted as being important for monitoring and identifying El Niño and La Niña. The most common ones are the NINO regions (see also Figure 2 below):
- NINO1+2 (0-10S, 80-90W). The region that typically warms first when an El Niño event develops.
- NINO3 (5S-5N; 150W-90W). The region of the tropical Pacific that has the largest variability in sea-surface temperature on El Niño time scales.
- NINO3.4 (5S-5N; 170W-120W). The region that has large variability on El Niño time scales, and that is closer (than NINO3) to the region where changes in local sea-surface temperature are important for shifting the large region of rainfall typically located in the far western Pacific.
- NINO4 (5S-5N: 160E-150W). The region where changes of sea-surface temperature lead to total values around 27.5C, which is thought to be an important threshold in producing rainfall.
Here's a map showing the different regions:
|Source: Earth Institute, Columbia University|
Sea surface temperatures (SST) provide another means of defining El Niño and La Niña in terms of NINO indices. If the five month running average of the NINO3.4 index is above +0.4°C for at least six consecutive months, then it's an El Niño. If it's below -0.4°C then it's a La Niña event. Kevin Trenberth discussed this in his 1997 paper "The Definition of El Niño".
So there are a number of different ways to monitor ENSO and different ways of defining ENSO events.
Differences in ENSO "years"
There are also differences in defining ENSO "years". ENSO events aren't very accommodating for those of us who would like to say, for example, that 1998 was a big El Niño year - in that they don't conveniently run from January to December.
For example, looking at the period starting in April 1997, over the 12 months from April 1997 to March 1998 there was a strong El Niño. Then starting in May 1998 right through to March 2001 (with a few ups and downs) there was a moderate La Niña event.
This article meandered a bit. I wasn't trying to write everything there is to be known about the El Niño Southern Oscillation in one blog article. That would be impossible. Apart from the fact that I'm not an expert in this topic, the subject is vast. Not only that, it's still an active area of research. What I was exploring was just where Bob Tisdale goes off the rails and deviates from science. (I probably got some things wrong myself. If so, hopefully a reader will be good enough to correct me.)
There are differences other than what I've mentioned already.
Bob says: They (ENSO events) are the dominant mode of natural climate variability on annual, multiyear and decadal timeframes.
ENSO events do affect large areas of the world so I'd agree they have a dominant affect on annual and multi-year time frames, at least in the tropics and mid-latitudes. I don't think his "decadal timeframes" is correct. ENSO events operate on annual and at multi-year time frames but it's rare for individual events to have a marked impact beyond ten years or so as far as I know. At the decadal time scale, there are other things like the Pacific Decadal Variation and the Arctic and the North Atlantic Oscillations. The Pacific Decadal Variation (PDV) or Pacific Decadal Oscillation is discussed in the Wang paper I referred to above, which draws some parallels between the PDV and ENSO and states in part:
The ENSO and PDV patterns are very similar, not only over the tropical Indo-Pacific but also globally. In particular, when SST anomalies are positive in the tropical eastern Pacific, they are negative to the west and over the central North and South Pacific, and positive over the tropical Indian Ocean and northeastern portions of the high-latitude Pacific Ocean. The primary difference between the PDV and ENSO patterns is that PDV lacks the narrow equatorial Pacific maximum that is the hallmark of ENSO. For this reason, PDV is often referred to as a “broadened ENSO pattern”.
Bob refers to an "equatorial countercurrent". This website gives a short description of the ocean currents in the region of the equatorial Pacific and how they change with ENSO.
At one point Bob "digresses" rather badly, showing his science denial, writing:
Of course, some publicity seeking climate scientists continue to (very unwisely) blame carbon dioxide for the heat waves and cold spells, flooding and drought, blizzards and low snowfall, creating further disbelief in climate science. They have only themselves to blame for their loss of credibility. I digress.
I suspect that because Bob has managed to learn a bit about the mechanics of ENSO he thinks he knows all there is to know about weather and climate. Dunning-Kruger writ large. He has a blind spot when it comes to the greenhouse effect and doesn't believe in it. Bob can't accept the physics of climate. Climatologists know the difference between a regular heat wave and greenhouse gas forcing. (Increasing greenhouse gases means that energy takes longer to be radiated to space. In other words, even if energy came in from the sun at the same rate it takes longer to leave, so it builds up in the system. This build up of energy continues as long as greenhouse gases keep building up.)
Bob writes: "El Niño events are the abnormal phase of ENSO". As you'll have seen from the Wang paper I referenced, it's not necessarily regarded as abnormal. In some models it's merely one phase of a self-sustaining oscillator. However it's true that there are more differences between El Niño and neutral than between La Niña and neutral phases. La Niña could even be described as an exaggeration of the neutral phase. Whereas El Niño is quite different in terms of atmospheric circulation as well as sea surface temperatures and the thermocline in the eastern Pacific.
The main crux of Bob's "ENSO causes global warming" argument is, I think, encapsulated in this statement of his:
the climate science community has failed to account for the “leftovers”, the residual warm water, from strong El Niños.
I'm at a loss to understand what Bob means by this statement. Certainly the reason the surface temperature rises in an El Niño is because of the large expanse of warm water that's spread out over the Pacific which heats up the atmosphere. But although this shows up in the sea surface temperature changes, the ocean as a whole would barely notices this heat loss. As stated on this page of course notes from Columbia University (which is what got me thinking about how Bob interprets ENSO) (my bold italics):
Think of the tropical Pacific as a huge tub, with the waters sloshing back and forth. In the cold phase the warm waters are low in the east, so they must be high somewhere else. This is because water is conserved and because warm water is very nearly conserved: there is some heat exchange with the atmosphere, but from the ocean's point of view it doesn't amount to much. (From the atmosphere's point of view its quite a lot -- it is just this rearrangement of the atmospheric heating that sets off the worldwide climate anomalies associated with El Niño.)
In another section Bob writes the following, where he talks about warm water below the surface being "excluded" from the surface temperature record:
Warm water that has traveled east during the El Niño and that is not “exhausted” by the El Niño does not remain in the eastern tropical Pacific. It is returned to the West Pacific and Indian Oceans, where much of it remains on the surface. Before the El Niño, most of that warm water is below the surface of the west Pacific Warm Pool and excluded from the surface temperature record. Then, after the El Niño, part of what remains of that warm water is now on the surface of the West Pacific and East Indian Oceans. The opposite does not occur during the La Niña phase. The result: strong El Niño events can raise global sea surface temperatures for extended periods of time.
I think Bob is obliquely referring to some bee that's got caught in his bonnet about the relationship between sea surface temperatures and global warming. He does spend a lot of time elsewhere writing about sea surface temperatures. However I can't claim to know just what it is he is thinking. I don't know for sure if this is the point at which he decided that the oceans are causing global warming. It could be that he thinks that sub-surface water is coming to the surface and heating the atmosphere and causing global warming. His argument falls apart quickly when you think that ENSO has been operating for millennia without Earth heating up, until now. In any case, there is no inexhaustible supply of hot water under the ocean surface. If there were, then Earth would have become too hot to live on long before now. You can't heat the ocean by magic, which is what Bob's proposal amounts to. (It's possible that Bob thinks that one of these days soonish the oceans and Earth will cool again and global warming will reverse. But I can't tell from this article just what's going on in that head of his. Added later: No, he doesn't. In a comment copied below Bob reiterates that he thinks that ENSO is going to continue to heat up the world. Forever, presumably. Maybe he's got a berth on the next commercial space flight to somewhere more habitable than his notion of future Earth.)
Bob also says "The opposite does not occur during the La Niña phase". But during La Niña cold water upwells from the eastern Pacific. I figure it's worth looking more closely at what Bob is trying to say. He wrote:
Before the El Niño, most of that warm water is below the surface of the west Pacific Warm Pool and excluded from the surface temperature record.
Here is the neutral phase, from BoM, showing the warm pool in the western Pacific. It does extend down below the surface:
Bob then writes:
Then, after the El Niño, part of what remains of that warm water is now on the surface of the West Pacific and East Indian Oceans.
Well, this is what happens during El Niño:
The warm water moves eastwards and spreads out and up, warming the atmosphere. And the water in the western Pacific cools down during El Niño. Afterwards, the warm water moves back to the west, being driven by the trade winds that strengthen again during either a neutral phase or another La Niña. Bob I think is trying to argue that the heat somehow keeps building up in the oceans over successive ENSO events, without dissipating. He's wrong. Physics won't allow it and observations show it hasn't happened. The Earth as a whole is only heating up now because of the extra greenhouse gases that slow the escape of energy to space. The oceans themselves don't "trap" heat so that they get hotter and hotter without some additional forcing. (That's not to say that some individual events aren't stronger than others. They are. But over time, if all else is equal, ENSO events don't add heat to the Earth system.)
I could be wrong about what Bob is trying to argue. Maybe a reader has a clue of what Bob is getting at.
One thing we do know, because he's said it on more than one occasion, is that Bob thinks that ENSO is causing global warming. Another thing we know is that Bob doesn't accept the greenhouse effect. And another thing we know is that Bob is using WUWT to try to sell his various books to other science deniers. Anthony Watts seems only too happy to help out a penurious pal (he hasn't yet met).
From the WUWT comments
January 10, 2014 at 5:52 am
Now I need to go back and read your previous posts on how folks try to “remove” the influence of ENSO from the temperature record. I seem to remember you criticizing the fact that much of the residual warm surface water remains long after the actual El Nino event and they were therefore not correcting for El Nino’s properly. I don’t recall whether you opined whether this adjustment can be done at all or offered an alternative adjustment of your own.
Ron Richey asks a good question and says:
January 10, 2014 at 7:30 amThis article might shed some light - or not. And this paper spans, not a serious glacial but the Little Ice Age.
Sweet! – I actually get thisnow. Only took about a half hour.
Couple of “dummy” questions:
What happens to ENSO during an ice age?
Does ENSO cause or contribute to ice ages or warm ages?
James Strom uses faulty logic and says the scientists have it all wrong:
January 10, 2014 at 8:31 am
Good stuff, Bob. You’ve answered a question that has been nagging me for quite a while: Is the warming associated with El Nino merely a rearrangement of existing heat or somehow an addition to the Earth’s total heat energy? To a significant degree it must be the former. As you say the waters of the warm pool get moved into locations where they are more fully available to our efforts at measurement. So your essay also points to a significant source of error in our measurment of global temperature.
Michael Barnes is one of several who asks a question relating to density and/or salinity and says:
January 10, 2014 at 8:48 am
Curiosity question: Since the water in the West Pacific Warm Pool is warmer than the water in the Cold Tongue Region, the water in the West is less dense than the water in the East. Is this explicitly accounted for? How much does it matter?
Thank you for the pictures.
Lance Wallace says:
January 10, 2014 at 8:54 am
If ENSO is just a natural oscillation, why do we see these step-like shifts in global atmospheric temperatures after powerful El Ninos such as 1997-98?
John L Kelly writes the "comment of the day" and says:
January 10, 2014 at 10:47 am
This all sounds absolutely wonderful. However you, like the rest of the world, continue to underestimate the Heat From Within the planet. Consider, if the sun is the main ingredient here, then why doesn’t this oceanic heating occur all over the planet? Why is this happening exclusively within the Ring Of Fire? Why just the Pacific?
I’ll tell you why. El Nino is the result of the heat from within, escaping along the deep oceanic floor, through plates/vents, where the heat radiates upward/outward, until it reaches the oceanic surface, and then moves into the atmosphere, along with moisture, and there it move along the jet stream, causing the El Nino effect we all know. and when it slows down, La Nina occurs.
If you refuse to see this, fine. I personally don’t care. That’s your problem. But like Continental Drift, its time will arrive, whether you like it or not. Just remember this and know where you read it first.
It looks as if Bob Tisdale really does think there is an ever upward shift in ocean temperatures, going by this comment of his. Bob Tisdale says (excerpt):
January 11, 2014 at 5:06 am
Will we go another couple of decades before another strong El Niño causes another upward shift in the East Indian-West Pacific sea surface temperature data? We’ll have to watch and see.