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Global warming and the El Niño Southern Oscillation

What the science says...

Select a level... Basic Intermediate

El Nino has no trend and so is not responsible for the trend of global warming.

Climate Myth...

It's El Niño

"Three Australasian researchers have shown that natural forces are the dominant influence on climate, in a study just published in the highly-regarded Journal of Geophysical Research. According to this study little or none of the late 20th century global warming and cooling can be attributed to human activity. The close relationship between ENSO and global temperature, as described in the paper, leaves little room for any warming driven by human carbon dioxide emissions. The available data indicate that future global temperatures will continue to change primarily in response to ENSO cycling, volcanic activity and solar changes." (Climate Depot)

At a glance

This particular myth is distinguished by the online storm that it stirred up back in 2009. So what happened?

Three people got a paper published in the Journal of Geophysical Research. It was all about ENSO - the El Nino Southern Oscillation in the Pacific Ocean. ENSO has three modes, El Nino, neutral and La Nina. In El Nino, heat is transferred from the ocean to the atmosphere. In La Nina, the opposite happens. So within ENSO's different modes, energy is variously moved around through the planet's climate system, but heat is neither added nor subtracted from the whole. As such, in the long term, ENSO is climate-neutral but in the short term it makes a lot of noise.

The paper (link in further details) looked at aspects of ENSO and concluded that the oscillation is a "major contributor to variability and perhaps recent trends in global temperature". First point, sure. Second point, nope, if you accept climate trends are multidecadal things, which they are.

That might have been the end of it had the authors not gone full-megaphone on the media circuit, promoting the paper widely in a certain way. "No scientific justification exists for emissions regulation", they loudly crowed. "No global warming", the denizens of the echo-chamber automatically responded, all around the internet. This is how climate science denial works.

Conversely, the way that science itself works is that studies are submitted to journals, peer-reviewed, then some of them get published. Peer review is not infallible - some poor material can get through on occasion - but science is self-correcting. So other scientists active in that field will read the paper. They may either agree with its methods, data presentation and conclusions or they may disagree. If they disagree enough - such as finding a major error, they respond. That response goes to peer-review too and in this case that's exactly what happened. An error so fundamental was found that the response was published by the same journal. The error concerned one of the statistical methods that had been used, called linear detrending. If you apply this method to temperature data for six months of the Austral year from winter to summer (July-December), it cannot tell you that during that period there has been a seasonal warming trend. So what happens if you apply it to any other dataset? No warming! Bingo!

A response to the response, from the original authors, followed but was not accepted for publication, having failed peer-review. At this point, the authors of the rejected response-to-the-response started to screech, "CENSORSHIP" - and the usual blogosphere battles duly erupted.

It was not censorship. Dodgy statistical techniques were picked up by the paper's highly knowledgeable readership, some of whom joined forces to prepare a rebuttal that corrected the errors. The response of the original paper's authors to having their errors pointed out was so badly written that it was rejected. That's not censorship. It's about keeping garbage out of the scientific literature.

Quality control is what it's all about.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

ENSO, the El Nino Southern Oscillation, is an irregular but well-understood phenomenon that affects the Eastern and Central Pacific Oceans. It is important both on a local and global basis, since it not only causes changes in sea-surface temperatures. It also affects the thermal profile of the ocean and both coastal and upwelling ocean currents.

Such changes can and do affect the diversity and abundance of important edible seafood species. Cold and warm-water forms are forced to migrate to where they find the conditions more to their liking. El Nino events in particular, where warm waters prevail close to the sea surface, can inflict a temporary loss of commercially important species of fish and squid from where they are traditionally fished. Some coastal communities along the Pacific seaboard of South America have a strong dependency on such fisheries. As such, prolonged El Nino conditions can be seriously problematic.

The warm El Nino mode of ENSO also affects global temperatures, as heat energy is transferred from ocean surface to the atmosphere. A strong El Nino is easily capable of raising temperatures above the upward slope that represents the change in radiative forcing caused by our increasingly vast greenhouse gas emissions - global warming, in other words. Conversely, the opposite to El Nino, La Nina, suppresses global temperatures. When several La Nina years occur in a row, climate science deniers are given the opportunity to insist that the world is cooling. This has happened before, most notably in the post-1998 period.

However, as fig. 1 shows, global temperature is rising independently of the short-term ENSO noise. Fig. 1 also shows that 2022 was the warmest La Nina year in the observational record. In fact, El Nino, La Nina and neutral years are all getting warmer.

Variations in ENSO in a warming world.

Fig. 1: variations in ENSO in a warming world. This plot therefore shows two independent phenomena that affect climate: the noisy ENSO and the underlying relentless upward climb in temperatures caused by our rapidly-increasing emissions of CO2 and other greenhouse gases. Temperature records typically get broken in El Nino years because the temperature is given an extra boost. 2016, a major El Nino year, held the global temperature record for a few years, but 2023 saw that record fall again. 2023 is in grey because that El Nino did not develop until later in the year. Graphic: Reaclimate.

The reader should by now be in no doubt about the difference between the long term global temperature trend caused by increased greenhouse gas forcing and the noise that shorter-term wobbles like ENSO provide. You would have seen something similar during the descents into and climbs out of ice-ages too. That's because ENSO has likely been with us for a very long time indeed. Ever since the Pacific Ocean came close to its present day geography, millions of years ago, it has likely been there.

The reader should by now be in no doubt about the difference between the long term global temperature trend caused by increased greenhouse gas forcing and the noise that shorter-term wobbles like ENSO provide. You would have seen something similar during the descents into and climbs out of ice-ages too. That's because ENSO has likely been with us for a very long time indeed. Ever since the Pacific Ocean came close to its present day geography, millions of years ago, it has likely been there.

Nevertheless, here we have something that warms the planet, even if that's on a temporary basis. As a consequence, some people with ulterior motives might just become interested. Over a decade ago now, that's what happened. A paper, 'Influence of the Southern Oscillation on tropospheric temperature' (Mclean et al. 2009) was published in the Journal of Geophysical Research. One of its co-authors, a well-known climate contrarian, commented:

"The close relationship between ENSO and global temperature, as described in the paper, leaves little room for any warming driven by human carbon dioxide emissions."

If you enter the above quote, complete with its quotation marks, into a search engine, you will get lots of exact matches. Strange? Not really, if you have studied the techniques of climate science denial.

  1. a paper is published that barely mentions global warming.
  2. its authors go on to distribute slogans implying that they have put yet another Final Nail in the global warming coffin.
  3. right-wing media of all sorts from newspapers to blogs ensure wide distribution of the talking-points.
  4. individuals serve to fill in the circulation-gaps.

This is how it works, time and again. However, glaring errors were soon noticed in the paper, leading a group of specialists to offer a rebuttal, published in the same journal a year later (Foster et al. 2010).

Statistics is not everyone's cup of tea, but a very straightforward explanation of the key error was provided by Stephen Lewandowsky, writing at ABC (archived):

"This is best explained by an analogy involving daily temperature readings between, say, July and December anywhere in Australia. Suppose temperature is recorded twice daily, at midday and at midnight, for those 6 months. It is obvious what we would find: Most days would be hotter than nights and temperature would rise from winter to summer. Now suppose we change all monthly readings by subtracting them from those of the following month—we subtract July from August, August from September, and so on. This process is called "linear detrending" and it eliminates all equal increments. Days will still be hotter than nights, but the effects of season have been removed. No matter how hot it gets in summer, this detrended analysis would not and could not detect any linear change in monthly temperature."

Anyone can do this in Excel. First input a series of representative temperatures for the transition from Austral winter into summer:

Series of representative temperatures for the transition from Austral winter into summer.

Reasonable? OK, then let's plot them. Still looks like what we'd expect. It gets warmer in Australia from July to December and nights are usually colder than days, right?

Plot of temperatures

Now, let's do that detrending. This is what you get:

Detrended temperatures

As Lewandowsky pointed out in his ABC article:

"Astonishingly, McLean and colleagues applied precisely this detrending to their temperature data. Their public statements are thus equivalent to denying the existence of summer and winter because days are hotter than nights."

In other words: Fail.

Last updated on 24 March 2024 by John Mason. View Archives

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Argument Feedback

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Further reading

NOAA have a very useful resource ENSO Cycle: Recent Evolution, Current Status and Predictions which features recent ENSO activity as well as model predictions of ENSO activity in the near future.

Denial101x video


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Comments 1 to 25 out of 206:

  1. Great post. Another point - your Figure 1 shows the basic problem with this claim at a glance. The grey temperature line has a discernible upward trend, while the dark ENSO line does not. So ENSO doesn't match the warming trend, case closed. However, as the paper itself is behind a paywall, the key findings have been posted here, with the graph split into three at 1980 and 1995: With this split, the warming trend is much harder to spot. You can do the same thing with surface temps (NASA GISTEMP): GISTEMP 1958-2009 - trend is clear GISTEMP 1958-2009 in 3 slices - trend obscured A "trick" to "hide the incline" perhaps?
  2. Erl - for a warming trend, you have to increase the net energy on the planet. Where is the evidence of this in ANY ocean cycle. While the initiation point of an ENSO event remains tricky, (is it wholly a dynamical phenomena?), I would say that other aspects are now pretty well understood. I also note that "ENSO" emerges in climate models, and yet these models do not create temperature trends unless there is a forcing (like CO2 or solar) applied.
  3. scaddenup #2 My understanding is that ENSO, La Nina, AMO etc are internal re-distributions of heat energy around the globe - not overall gain or loss of heat from the Earth system to space by forcing imbalances.
  4. Ken. So do I but Erl apparently does not.
  5. Please read: Tell me this: What is responsible for the long term change in the differential pressure that drives the trade winds and tropical temperature?
  6. Continuing from #20 on the Goddard-is-cherrypicking-sea-level-data thread. The same statement was made as in #3 here: ENSO are, after all, cycles, which don't make much difference in the long term. However, as the familiar MEI graph shows, there seems to be a lot more red since about 1977 or so. From a fascinating model run made by Timmerman et al. 1999: The tropical Pacific climate system is thus predicted to undergo strong changes if emissions of greenhouse gases continue to increase. The climatic effects will be threefold. First, the mean climate in the tropical Pacific region will change towards a state corresponding to present-day El Nino conditions. It is therefore likely that events typical of El Nino will also become more frequent. Second, a stronger interannual variability will be superimposed on the changes in the mean state, so year-to-year variations may become more extreme under enhanced greenhouse conditions. Third, the interannual variability will be more strongly skewed, with strong cold events (relative to the warmer mean state) becoming more frequent. If I read that correctly, sounds like more red overall with the occasional deeper blue.
  7. Isn't the El Nino Southern Oscillation showing a long term trend towards stronger and more frequent El Ninos because of global warming? Because I read a myriad of studies suggesting this. But in recent years that trend seems to be dissipating or is too short of a time period to make any meaningful judgements? Is this trend towards stronger and more frequent El Ninos truly manifesting itself or is it just a fluke of nature?
  8. #7: "I read a myriad of studies suggesting this." It would be helpful if you would provide some references, rather than just 'a myriad.' "But in recent years that trend seems to be dissipating or is too short of a time period to make any meaningful judgements?" Look at the graph in #6. What 'trend seems to be dissipating' are you referring to? Also note the 2nd and 3rd points from the Timmerman paper: - year-to-year variations may become more extreme and - with strong cold events (relative to the warmer mean state) becoming more frequent. Or to put it in terms of a 'forecast': Continued warming with a 30% chance of occasional heavy snow in some areas. 50% chance of record droughts and/or record flooding. 95% chance of skeptics refusing to look at the long term and seizing on minimal data to say 'No its not!' 100% chance of inaction on the part of the US government.
  9. I would like to see an article where the ENSO argument of Bob Tisdale is being countered. The ENSO argument presented here is not the main skeptical argument on ENSO, after all. Tisdale is going further, claiming that the NINO3.4 index does not fully account for ENSO as a process. He purports to show that when the entire set of processes involved in the progression of the ENSO phenomenon is included, the ENSO IS able to explain global warming since the mid 70s. I would like to see you tackle HIS argument to show specifically where it fails. In my opinion, this site would not be complete without such an article.
  10. Kayell, If any real people took Tisdale's argument seriously, then this site would tackle it. This site is not, however, required to tackle every bit of nonsense generated by every person on earth. The fact that Tisdale's cr@p gets play on WUWT is meaningless (and says a lot about WUWT and its readership). Those people are lost, and will stay lost. For what it's worth, however, Tisdale's entire collage of nonsense fails on one basic point, the First Law of Thermodynamics. From where does the energy come that allows ENSO to heat the planet? Put another way, ENSO has been around for thousands of years. Why, suddenly, now, does each successive El Nino warm the planet (which is actually the opposite, La Nina's warm the planet), while La Nina's have no counteracting effect? Why is heat suddenly accumulating now due to ENSO, yet never before today? What's changed? What is the physical mechanism at work? And before you ask, no, I haven't paid good money to read his cr@ppy theories, and I won't. If you'd like to send a PDF of his nonsense, and if I decide I'm willing to waste a chunk of my life looking at it, then it can maybe discussed (although, really, I'd rather spend my time looking at real science that is going to affect the course of policy, not sideline nutjobbery that is really of no consequence to anything). Short of that... no, I don't see the need for SkS to debunk every bit of Galilean look-at-me-I've-got-it-I'm-a-genius nonsense that exists in the world.
    Response: [Dikran Marsupial] Please keep the discussion to the science and avoid inflamatory terms, regardless of the perceived provocation.
  11. Wow, that was really quite an aggressive response, I must say. Where did that come from? You keep calling his ENSO argument 'crap' and 'nonsense'. And yet you admit you haven't actually read what he says, what his argument in full is all about. Sounds like pure reflexive dismissal to me. If this is such a nutcase piece of hypothesizing, then it should be exceedingly easy to actually show specifically where it fails. Your 1st law of thermodynamics counter-argument is of course only based in you not having read what he says of the matter. You know, I know and he knows where the energy is coming from. You know, I know and he knows how the Pacific uptake of solar energy varies wildly between La Niña and El Niño conditions.
    Response: [Dikran Marsupial] Please can EVERYBODY keep the discussion even tempered, or I will start deleting posts.

    Kayell: I suspect the tone of the reply was prompted by the rhetorical tone of your initial post "In my opinion, this site would not be complete without such an article. ". If you keep your posts purely scientific and avoid rhetoric you will find you get a much better response. If you want an argument addressed, then at least provide a link to where the argument is presented. If you know where the energy is coming from, then you ought to be in a position to debunk the argument yourself.
  12. Kayell, I'm not paying good money to Tisdale to read his nonsense. Period. [snip] [Why do you think it is that no-one except for WUWT regulars are paying any attention to his theory?]
    Response: [Dikran Marsupial] Discussion of motivations snipped. Please lets just keep this to the science, and wait and see if Kayell can come back with a more substantive description of the argument.
  13. Presumably Tisdale shows that ENSO's influence has become far more extreme over the past few decades, that it is unleashing astounding quantities of formerly stored and hidden energy? Does he explain how that works? Or does the hypothesis only work if explained in isolation from other evidence? For instance, the overwhelming balance of evidence indicates that Arctic sea ice is going through area excursions and persistent volume loss in a way that's very unusual and likely not to have taken place for many thousands of years. For this to happen requires some input of additional heat energy to the Arctic Ocean and indeed other measurements confirm that's the case. Given the timeline of Arctic sea ice behavior, integrating these observations of sudden change with Tisdale's approach requires some mechanism that could sequester energy for many thousands of years and then suddenly release it. How does that work? As we all know, energy in the form of heat is very difficult to keep in one place. So what's the storage mechanism for Tisdale's energy?
  14. Kayell - Tisdale's argument appears to be that the ENSO is not symmetric, that La Nina absorbs more energy than El Nino releases, and thus the heat content of the Earth rises in 'steps'. Problems with his hypothesis: * Why would the ENSO be asymmetric now, when it hasn't been for the last few hundred years - effects require causes and mechanisms, and he has proposed nothing plausible in that regard. * The oceans and the atmosphere have warmed, especially over the last 40 years - and given the Stefan-Boltzmann relationship of emitted power with temperature, if the atmosphere was radiatively unchanged we would have a negative (cooling) top of atmosphere (TOA) balance. The evidence shows a postive balance (less leaving than arriving), thus contradicting Tisdale. This is a major problem with any number of 'skeptic' theories. * His evidence (what there is of it) consists of extremely short "step" changes of sea surface temperatures - and as has been discussed here and elsewhere (as in the Escalator graphic), those are artifacts of noisy data and statistically insignificant short term trends. * Observed warming (25*10^22 Joules over the last 40 years in the top 2000 meters of the oceans) has occurred in a fairly steady rise. Not by "steps". * His statistics, if you can call them that, are terrible - he doesn't know enough to numerically support his hypotheses, and what he presents actually contradicts his ideas if you actually know what the numbers mean. --- In short, Tisdale's hypotheses consist of handwaving over statistically meaningless short periods and changes. None of it has been peer-reviewed, he is clearly not familiar with the body of peer-reviewed science and data on the issue, it's unsupported and unsupportable pixie dust. And it's rather frustrating to see such nonsense taken seriously by anyone, let alone be pushed repeatedly by Tisdale in his insulting and accusatory terms (multiple accusations of deception, conspiracy, data manipulation, etc). Hence the impatience from those who know anything about the ENSO and global warming...
  15. Kayell - "...claiming that the NINO3.4 index does not fully account for ENSO as a process..." I find this a very curious strawman argument. The NINO3.4 index is one measure (of many) of an acyclic process - consisting of wind driven changes in ocean overturn and hence heat exchange with the atmosphere. That index is not the process. I cannot think of anyone who has claimed it is (hence the strawman). It is, rather, one measure of that process, much as GDP is one measure of economic activity. If the ENSO index is insufficient to track the process, then what ENSO aspects does Tisdale think have changed in the 1970's? And why? How would he measure that, in a statistically significant fashion - where is his evidence? His favorite measure, sea surface temperature changes in various regions, is actually part of the NINO3.4 index; he's presented nothing new. As I said at the start, attacking the index is a Strawman Fallacy. The ENSO can be measured/tracked with trade winds, with atmospheric pressures (Southern Oscillation Index, SOI), or with sea surface temperatures (as in the NINO3.4 index). If Tisdale thinks these are insufficient, it is on him to present evidence of supportable process changes that have diverged from historic behaviors. He has not.
  16. Sphaerica - "Put another way, ENSO has been around for thousands of years" ENSO has been around for millions of years. There are enough people responding to Kayell, so I'll stay out of this.
  17. Frankly, I would think you would pounce on the opportunity to rip this particular ’skeptical’ argument apart, to present a clinical, blow-by-blow refutation of it. It is (still in MY opinion, though) the most robust, cohesive skeptical argument AGAINST an anthropogenic and FOR a natural cause of global warming out there. And it’s getting more and more traction amongst ’the skeptical crowd’. So it is indeed a real, important and relevant skeptical argument. It is an easy to grasp argument, mostly descriptive actually, and does not make use of any models or sets of novel assumptions, only available data. The physical mechanisms at work and their effects are readily observable through space and time and well known and described in the geophysical literature. In a way the argument explains itself once you understand the processes at hand and simply track the energy through the Earth system by looking at the various sets of data. If you’ll let me, I would be happy to give you a compendious summary of the argument.
    Response: [DB] As noted by Phippe and KR below, the skeptical thing to do would be to first address those questions already put to you on this thread. Those genuinely interested in advancing the scientific understanding should feel that to be an imperative.
  18. Kayell, why don't you start by adressing the robust, cohesive relevant critics to the very premise of that argument that have already been presented above by various contributors? That would be a necessary first step. Also, keep in mind that here we concern ourselves with scientific arguments that are supported by peer-reviewed scientific litterature; Tisdale's piece not only doesn't fit that description but also betrays a lack of familiarity with the relevant scientific litterature by its author. There is no doubt that the "argument" will gain traction among those with little scientific literacy on the subject, especially if they're frantically looking for any old useable bit to confirm what they want to believe. It doesn't make it better than any other argument that particular public will buy.
  19. Kayell / Kristian - I believe I have discussed Tisdale's arguments in some detail. I would be interested in any comments you might have on the lack of statistical significance of his "step" time periods, the positive (increasing energy) TOA balance that directly contradicts his ENSO attribution of global warming, the fact that sea surface temperatures (SST's) he argues from are actually included in both the NINO3.4 index and the MEI, etc. Well? What processes does Tisdale point to, processes that for some reason have changed from their many 10's of thousands of years history to suddenly warm the earth over the last 150? You know, evidence? Please point to data supporting your assertions, as per the opening post. (I'm afraid I will not take hand-waving very seriously...)
  20. Philippe Chantreau and KR, Since people here so far haven't adressed the actual argument at all, only their strawman versions of it, I see no reason spending time answering their/your appararent objections. Rather I would prefer presenting the argument. Dikran, are you seriously asking me to answer all these 'objections' to the argument before I actually describe the argument to you? That's a strange way of advancing a discussion ...
    Response: [Dikran Marsupial] Kayell, I am telling you to avoid rhetoric and instead stick to the science. If you want people to discuss Tisdales argument then either explain it in detail yourself, or provide a link to somewhere that does. The first law of thermodynamics is a perfectly good explanation of why Tisdales argument is wrong. If you have an objection then present it. If you continue to avoid discussing the science you will be making it clear that you are not interested in the answer to your questions and are merely trolling. The ball is in your court, I suggest you return it.
  21. Kayell / Kristian - If you feel I have incorrectly understood Tisdale's argument, perhaps you could (clearly) state what you feel his argument is? Or in some other fashion indicate what interpretive error you think has been made? ...without a statement of where you think the argument stands, it's absurd to claim that I (and others) have not addressed it. On my part, I believe I have addressed Tisdale's unsupported, and contradicted by evidence, hypotheses. Since you feel he's made a good argument, it falls upon you to state what that is, and why the various disagreements are (potentially) not valid. Barring that, I would (IMO) consider your posts so far on this thread to be assertions without evidence. "Rather I would prefer presenting the argument." By all means, please do.
  22. Kayell/Kristian - I said I'd stay out of this, but I've changed my mind. Bob Tisdale himself is unable to explain his hypothesis, so maybe you can have a shot at it? No one here is likely to waste one and a half hours watching his videos, so please explain to us what you find so compelling.
  23. For anyone interested, the discussion of the proposed mechanism starts at about 29:15.
  24. KR says: "By all means, please do." Thanks. That's all I'm asking for. I will. It'll take me more than five minutes though, and that's all I have to spare right now. So later.
    Response: [Dikran Marsupial] We will be patient, please do take time to present the argument carefully. I would recommend presenting it as a set of numbered steps that form the logical chain of the argument, I have found that works well in the past as then counter arguments can be discussed for each link in the chain separately in detail.
  25. Dikran says: "If you want people to discuss Tisdales argument then (...) explain it in detail yourself (...)" Exactly. I haven't yet presented it. [snip]
    Response: [Dikran Maruspial] You have been asked to present the argument, so please stop complaining about the tone of the discussion and present it so that we can have a productive discussion. I have snipped the remainder of your post so as not to distract further from discussion the science, if you want a positive reception then it is straightforward, stick to the science, regardless of perceived provocation.

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