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Global warming and the El Niño Southern Oscillation

What the science says...

The El Nino Southern Oscillation shows close correlation to global temperatures over the short term. However, it is unable to explain the long term warming trend over the past few decades.

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)

The paper claiming a link between global warming and the El Niño Southern Oscillation (ENSO)  is Influence of the Southern Oscillation on tropospheric temperature (McLean 2009). What does the paper find? According to one of it's authors, Bob Carter,

"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."

In other words, they claim that any global warming over the past few decades can be explained by El Niño activity.

How do they arrive at this conclusion? They begin by comparing satellite measurements of tropospheric temperature to El Niño activity. Figure 1 plots a 12 month running average of Global Tropospheric Temperature Anomaly (GTTA, the light grey line) and the Southern Oscillation Index (SOI, the black line).

Figure 1: Twelve-month running means of SOI (dark line) and MSU GTTA (light line) for the period 1980 to 2006 with major periods of volcanic activity indicated (McLean 2009).

The Southern Oscillation Index shows no long term trend (hence the term Oscillation) while the temperature record shows a long term warming trend. Consequently, they find only a weak correlation between temperature and SOI. Next, they compare derivative values of SOI and GTTA. This is done by subtracting the 12 month running average from the same average 1 year later. They do this to "remove the noise" from the data. They fail to mention it also removes any linear trend, which is obvious from just a few steps of basic arithmetic. It is also visually apparent when comparing the SOI derivative to the GTTA derivative in Figure 2:

Figure 2: Derivatives of SOI (dark line) and MSU GTTA (light line) for the period 1981–2007 after removing periods of volcanic influence (McLean 2009).

The linear warming trend has been removed from the temperature record, resulting in a close correlation between the filtered temperature and SOI. The implications from this analysis should be readily apparent. El Niño has a strong short term effect on global temperature but cannot explain the long term trend. In fact, this is a point made repeatedly on this website (eg - here and here).

This view is confirmed in other analyses. An examination of the temperature record from 1880 to 2007 finds internal variability such as El Nino has relatively small impact on the long term trend (Hoerling 2008). Instead, they find long term trends in sea surface temperatures are driven predominantly by the planet's energy imbalance.

There have been various attempts to filter out the ENSO signal from the temperature record. We've examined one such paper by Fawcett 2007 when addressing the global warming stopped in 1998 argument. Similarly, Thompson 2008 filters out the ENSO signal from the temperature record. What remains is a warming trend with less variability:

Figure 3: Surface air temperature records with ENSO signal removed. HadCRUT corrections by Thompson 2008, GISTEMP corrections by Real Climate.

Foster and Rahmstorf (2011) used a multiple linear regression approach to filter out the effects of volcanic and solar activity and ENSO.  They found that ENSO, as measured through the the Multivariate ENSO Index (MEI), had a slight cooling effect of about -0.014 to -0.023°C per decade in the surface and lower troposphere temperatures, respectively from 1979 through 2010 (Table 1, Figure 4).  This corresponds to 0.045 to 0.074°C cooling from ENSO since 1979, respectively.  The results are essentially unchanged when using SOI as opposed to MEI.

Table 1: Trends in  °C/decade of the signal components due to MEI, AOD and TSI in the regression of global temperature, for each of the five temperature records from 1979 to 2010.

table 3

Figure 7

Figure 4: Influence of exogenous factors on global temperature for GISS (blue) and RSS data (red). (a) MEI; (b) AOD; (c) TSI.

Like Foster and Rahmstorf, Lean and Rind (2008) performed a multiple linear regression on the temperature data, and found that although ENSO is responsible for approximately 12% of the observed global warming from 1955 to 2005, it actually had a small net cooling effect from 1979 to 2005.  Overall, from 1889 to 2005, ENSO can only explain approximately 2.3% of the observed global warming.

Ultimately, all the data analysis shouldn't distract us from the physical reality of what is happening to our climate. Over the past 4 decades, oceans all over the globe have been accumulating heat (Levitus 2008; Nuccitelli et al. 2012, Figure 5). The El Niño Southern Oscillation is an internal phenomenon where heat is exchanged between the atmosphere and ocean and cannot explain an overall buildup of global ocean heat. This points to an energy imbalance responsible for the long term trend (Wong 2005).

Fig 1

Figure 5: Land, atmosphere, and ice heating (red), 0-700 meter OHC increase (light blue), 700-2,000 meter OHC increase (dark blue).  From Nuccitelli et al. (2012),

Data analysis, physical observations and basic arithmetic all show ENSO cannot explain the long term warming trend over the past few decades. Hence the irony in Bob Carter's conclusion "The close relationship between ENSO and global temperature leaves little room for any warming driven by human carbon dioxide emissions". What his paper actually proves is once you remove any long term warming trend from the temperature record, it leaves little room for any warming.

Intermediate rebuttal written by dana1981

Last updated on 10 July 2015 by pattimer. View Archives

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Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

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 176 to 200 out of 205:

  1. Bob Tisdale places great weight on “teleconnection” processes throughout his numerous posts. It is therefore critical for all involved in this discussion to have a common understanding of what “teleconnection” is. According to the IPCC, Teleconnection: A connection between climate variations over widely separated parts of the world. In physical terms, teleconnections are often a consequence of large-scale wave motions, whereby energy is transferred from source regions along preferred paths in the atmosphere. Source: Annex I (Glossary) to Climate Change 2007: Working Group I: The Physical Science Basis, IPCC Fourth Assessment Report. In comment #159, Tisdale asks HH: “On the other hand, are you aware of teleconnections? Are you aware that there’s no heat transfer with teleconnections?” Is Tisdale assuming that there is a distinction between “heat” and “energy”, or does he employ a different definition of “teleconnection” than that stated above?
  2. In my opinion, neither the OP nor Bob Tisdale provides an adequate explanation of ENSO. For an up-to-date and authoritative description of ENSO, see: El Niño and Southern Oscillation (ENSO): A Review by Chunzai Wang, Clara Deser, Jin-Yi Yu, Pedro DiNezio, and Amy Clement. Chunzai Wang , NOAA Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida Clara Dresser, National Center for Atmospheric Research, Boulder, Colorado Jin-Yi Yu, University of California at Irvine Pedro DiNezio, International Pacific Research Center, University of Hawaii Amy Clement, School of Marine and Atmospheric Science, University of Miami Abstract The ENSO observing system in the tropical Pacific plays an important role in monitoring ENSO and helping improve the understanding and prediction of ENSO. Occurrence of ENSO has been explained as either a self-sustained and naturally oscillatory mode of the coupled ocean- atmosphere system or a stable mode triggered by stochastic forcing. In either case, ENSO involves the positive ocean-atmosphere feedback hypothesized by Bjerknes. After an El Niño reaches its mature phase, negative feedbacks are required to terminate growth of the mature El Niño anomalies in the central and eastern Pacific. Four negative feedbacks have been proposed: reflected Kelvin waves at the ocean western boundary, a discharge process due to Sverdrup transport, western Pacific wind-forced Kelvin waves, and anomalous zonal advections. These negative feedbacks may work together for terminating El Niño, with their relative importance varying with time. Because of different locations of maximum SST anomalies and associated atmospheric heating, El Niño events are classified as eastern and central Pacific warming events. The identification of two distinct types of El Niño offers a new way to examine global impacts of El Niño and to consider how El Niño may respond and feedback to a changing climate. In addition to interannual variations associated with ENSO, the tropical Pacific SSTs also fluctuate on longer timescales. The patterns of Pacific Decadal Variability (PDV) are very similar to those of ENSO. 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. Many mechanisms have been proposed for explaining PDV. Changes in ENSO under global warming are uncertain. Increasing greenhouse gases changes the mean states in the tropical Pacific which in turn induce ENSO changes. Due to the fact that the change in mean tropical condition under global warming is quite uncertain even during the past few decades, it is hard to say whether ENSO is going to intensify or weaken, but it is very likely that ENSO will not disappear in the future. Particularly germane to the recent dialogue between Bob Tisdale and others on this comment thread are the two sentences that I have bolded in the above Abstract.
  3. "We will see if Bob returns......" Well, he did...after a fashion, saying many words, and answering few questions. Kevin C, stunning work! This entire thread has been most illuminating and educational.
  4. In spite of the volume of Bob Tisdale's comments, I still don't see how he accounts for the TOA energy imbalance. More energy is arriving than leaving: how does his hypothesis account for that?
  5. Bob Tisdale #158-163, thanks for at least making an attempt to answer my questions. Unfortunately, despite the verbose nature of your responses, you are still under the mistaken impression that you have a unidirectional energy imbalance driven by ENSO. You appear to conveniently highlight when heat is stored, while neglecting that heat is released during other phases of ENSO. Additionally, you completely avoid providing any sort of an explanation as to why ENSO would have fundamentally changed in the past century. This is, in fact, really important, as without this you are arbitrarily claiming that a unidirectional natural process magically came into being just in time to coincide with large industrial emissions of CO2. Your answer in #162 is almost comically poor, as it makes no attempt to come up with the necessary process or supply any evidence, it just verbosely dodges the question. I understand that the hordes at WUWT are rather easier to please, but it is actually necessary to have a physical mechanism that works beyond the last 30 years of data - as Kevin C has tried to show you. You top it off with some entertaining approaches to greenhouse physics. We observe less heat is escaping to space, at GHG-specific wavelengths (these are the same long-lived greenhouse gases that make Earth habitable), and more longwave radiation is observed to return to the Earth's surface, also at these GHG-specific wavelengths (e.g. Harries et al 2001, Philipona et al 2004 etc). Where is this heat going? You cannot escape this question by implying that the heat vanishes from the system simply beause longwave radiation does not penetrate deeply into the ocean directly! You're implying that all this energy is not accumulating in the Earth system, so it must, logically be escaping somewhere, in your world. Where? We can see it's not going into space. You seem to want to wish away the observed energy gain we see as a result of greenhouse gases (coincidentally what we have expected from a century of radiative physics), and you want to wish into existence a mysterious new unidirectional process causing the oceans to warm because of ENSO. But sadly, your answers are long on words, and short on physical mechanisms, and ultimately disappointing for those of us who want to be able to explain the full body of empirical evidence.
  6. @ skywatcher #180: Excellent summary of why Tisdale's dog will not hunt. Thank you for all that you do.
  7. Ron King. There is no period for which any oscillation has absolutely zero impact on a trend. As periods get longer, the impact gets smaller and smaller. In practice, over 130 years the impact of an ENSO magnitude oscillation is negligible. I haven't done the math required to figure out how long an interval you need to be confident that an ENSO magnitude oscillation would only impact the surface temp trend (for instance) +/- 0.01 c/decade. It'd be a fair bit more than 20 years.
  8. Li et al. 2013 might be a good basis for an intermediate article here:

    "Predicting how the El Niño/Southern Oscillation (ENSO) will change with global warming is of enormous importance to society. ENSO exhibits considerable natural variability at interdecadal–centennial timescales5. Instrumental records are too short to determine whether ENSO has changed6 and existing reconstructions are often developed without adequate tropical records. Here we present a seven-century-long ENSO reconstruction based on 2,222 tree-ring chronologies from both the tropics and mid-latitudes in both hemispheres. The inclusion of tropical records enables us to achieve unprecedented accuracy, as attested by high correlations with equatorial Pacific coral and coherent modulation of global teleconnections that are consistent with an independent Northern Hemisphere temperature reconstruction. Our data indicate that ENSO activity in the late twentieth century was anomalously high over the past seven centuries, suggestive of a response to continuing global warming. Climate models disagree on the ENSO response to global warming, suggesting that many models underestimate the sensitivity to radiative perturbations. Illustrating the radiative effect, our reconstruction reveals a robust ENSO response to large tropical eruptions, with anomalous cooling in the east-central tropical Pacific in the year of eruption, followed by anomalous warming one year after. Our observations provide crucial constraints for improving climate models and their future projections."

  9. Hey guys: Bob Tisdale’s crowing about the recent studies attributing slowed surface warming to La Nina:

    “Anyone with a little common sense who’s reading the abstract and the hype around the blogosphere and the Meehl et al papers will logically now be asking: if La Niña events can stop global warming, then how much do El Niño events contribute? 50%? The climate science community is actually hurting itself when they fail to answer the obvious questions.

    And what about the Atlantic Multidecadal Oscillation (AMO)? What happens to global surface temperatures when the AMO also peaks and no longer contributes to the warming?

    The climate science community skirts the common-sense questions, so no one takes them seriously."

    How’s this for a summary argument against the Tisdalian hypothesis (if it constitutes one):

    Tisdale and his crowd at WUWT seem to think temperature is just a number that just moves up and down somewhat arbitrarily, like a stock price.  They don't conceptualize things properly in terms of heat energy, which can't be created or destroyed.  

    ENSO doesn’t generate, absorb or destroy heat. So when Tisdale says La Nina “stops” global warming and El Nino “contributes”, he’s got it totally wrong. Nothing is being stopped – the heat energy is simply being moved around.  That's why we use the term "oscillation".  

    And the proper question to ask Tisdale is simply, Where is the heat coming from?


    I'm probably getting it all mucked up, as I have little science background, but I'm trying to put it in easy terms for non-sciencish people like myself.

    Also, what do you think of this graphic from Hotwhopper:

    ENSO without AGW:
    ENSO without AGW

    ENSO without AGW:
    ENSO with AGW

  10. Actually SkS has been writing about this oscillation for years, a.k.a the Interdecadal Pacific Oscillation (IPO). For the latest discussion see this recent(ish) SkS post: A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?.

    The oceans are warming due to the increased (enhanced) Greenhouse Effect (this is the upward slope in the 2nd graphic below), but the wind-driven ocean circulation moves back-and-forth between intense and sluggish phases, which results in the 'hiatus' and 'accelerated warming' decades. The net effect is illustrated in the graphics below:



    SkS will have upcoming posts/rebuttals explaining this in some more detail. You'll see how the observations by Kosaka & Xie (2013) tie in nicely with the wind-driven ocean circulation.

    Good to see Bob is slowly coming around to our way of thinking though. He still has a looooong way to go.

  11. Thanks for the info, Rob, but what do you think of my characterization of the problem with his hypothesis?  I'm trying to sum it up in a way that is hospitable to people like myself without a solid science background.

  12. dvaytw - it's not strictly true that El Nino and La Nina simply move heat around. But over time, in a stable climate, they would balance out to zero. The only reason the climate system is gaining energy in the long-term is because the increased Greenhouse Effect is trapping more heat in the surface ocean.

    That's why global temperature, and therefore subsurface ocean temperature, tracks atmospheric CO2 so well in the ice core records over the last 800,000 years.

    I don't consider it a worthwhile exercise spending time on crank ideas from Bob Tisdale.   

  13. Rob thanks.

    I understand why as a serious scientist you don't want to spend time on crank ideas. That said, I'm debating people in online forums where there are a lot of non-science people, and pseudo-scientists often know their pseudo-science better than do those defending the real science, which means they can actually appear to be winning debates even when wrong - and this can influence people's opinions.

    This is why I make the effort to actually find out what's wrong with Tisdale's "hypothesis" - because a fellow in a debate is using Tisdale's video about ENSO (which specifically targets SkS, incidentally!), and for the scientifically challenged, it can seem convincing.

    So based on your response, my next question is this: how do we know that "over time, in a stable climate, they would balance out to zero?" I seems in the information provided above, our measurements only go back to 1980.

  14. PS - is there a way to set the thread so I get an email notification when there's a response?

  15. This is perhaps a simple question but I see the Oceanic Niño Index (ONI) defined as "3-month running mean of SST anomalies (ERSST.v3, 1971-2000 base period) in the Niño 3.4 region"

    The NDJ nunber is shown as -0.4°C, which doesn't seem to be the mean of November 2013 (0.01°C) December 2013 (-0.04°C) and January 2014 (-0.51°C).

    Am I missing something terribly obvious?


    [JH] Link fixed.

  16. Maybe someone could explain a problem, I have with this topic.  If we conclude that the increase in global temperatures is not due to natural causes, can anyone explain the data contained on the NASA-GISS GLOBAL LAND-OCEAN TEMPERATURE INDEX graph located at the following web address: .

    This graph shows temperatures for the last 135 years.  If you will observe there is an almost "identical" increase in temperature shown for the periods of ~1910 to ~1942 and from ~1972 to ~2002.  The problem is that the level of CO2 was supposed to be fairly constant at 280ppm, until maybe the mid 1950's, and from the mid 1950's it was supposed to be increasing from 280ppm to its current value of 400ppm due to anthropogenic causes.  If you accept that the two periods of warming depicted on the graph are almost identical in duration and even slope/rate, what caused the first increase before AGW became a factor???  If it was natural causes like the PDO, AMO, NMO, AO, and maybe even changes in the Sun's radiation/magnetic field flux, why couldn't the same thing be responsible for the the period from 1972-2002??? 

    Additionally, If you will notice there is also a period between ~1942 and ~1972, which looks strangely like the current pause we have started to experience.  Maybe if you google: 


    Energy & Environment, Volume 21, Number 5, pp. 437-460, September 2010

    by Joseph D’Aleo and Dr. Don Easterbrook

    it might shed some enlightenment on this topic and the topic of "CAGW", especially when trying to explain the temperature graph mentioned above from the NASA-GISS website.  I presume this is acceptable data to the CAGW crowd.  Thank you for your time. 


    [JH] The use of "all caps" constitutes shouting and is prohibited by the SKS Comments Policy. In addition, making snarky statements on our comment threads is not acceptable.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  17. Dan Sage, you should rely on real data instead of "supposedlys."  CO2 levels have not been fairly constant until the mid 1950s; the rise got drastically steeper around 1950.

    Nobody claims that CO2 is the only driver of climate. (After you read the Basic tabbed pane, read the Intermediate one.) 

    Attribution of global warming across natural and anthropogenic causes has been studied exhaustively.  Relative contributions have varied, with correspondingly varying attributions of human versus natural over different periods.

  18. Dan Sage, for attribution of the causes of warming between about 1942 and 1972, see "Why did climate cool in the mid-20th Century?"

  19. Dan Sage, Don Easterbrook's claims are wildly wrong.

  20. Don Sage, for more insight to the errors (and "errors"--ahem) in Don Easterbrook's claims, see Dana's other Easterbrook post, "It's PDO," "It's the Sun," and "Climate's Changed Before."   Many Skeptical Science posts have Basic, Intermediate, and Advanced tabbed panes; read them all.  Also, be sure to post comments only on the relevant threads.  You can monitor all comments on all threads by clicking the "Comments" link in the horizontal blue bar at the top of every page.

  21. . . . and then there is Hot Topic's disassembly of Don Easterbrook's abuse of Central Greenland temperatures.

  22. Hi

    Climate models predicts higher air than sea temperature; is it el-niño effect no ?

    The last two big el niño were in phase with the 18.6 lunar tidal effect, it' s seems to have construct an hiher's seems to impeach la niña in the las two before that.

    The next is in 2034; sea surface temperature is actually far below the air temperature. Could we experience an almost flat line in the air temperature to 2034 while the sea surface will continue to rise gently ?

  23. Max or not @@197,

    It is difficult to understand much of what you actually ask.

    But regarding the 18;6 year cycle of the lunar orbital plane and ENSO. The 2015/16 El Niño did coincide with the 'minor lunar standstill'  which occurs every 18.6 years. And the 2015/16 El Niño was 18 years behind the 1997/98 El Niño. If the 18.6 year lunar cycle were triggering major El Niños perhaps there should have been a major El Niño in 1978/79 (2 x 18.6 yrs before 2015) and perhaps another in 1960/61 (3 x 18.6 yrs before 2015). Yet there wasn't. (See ONI data here.) That there were no such El Niños in those years surely suggests your proposed linkage between ENSO and the lunar orbit is solely based on a single conicidence that has not been repeated in the past, and so probably will not repeat in the future.

  24. I don't think it is the cause of el niño but that it is pushing ONI value higher whatever the value are negative, neutral or positive.

  25. Max or not @199,

    And what basis do you see for such "pushing"? The ENSO activity that we have record-of during previous 'minor lunar standstill' appear to be stiffled rather than pushed anywhere.

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