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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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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 76 to 91 out of 91:

  1. Sphaerica @74, the graph you have shown is the lagged global SST. A more direct comparison is without the lag: The differences between that graph and the first in your post are that I have used weekly rather than monthly data, and that I have rescaled by the ration of the Standard Deviations of the Data, ie, by multiplying the Nino 3.4 anomaly by 0.1224305012. Had I scaled the global SST to match Nino 3.4 as done in the first graph, the factor would have been 8.1678992563 rather than 10. In other words, that graph inflates the Global SST anomaly values by 22%. I also detrended the Nino 3.4 anomaly, and it is not clear that Tisdale has done so in the first graph. I hope that helps.
  2. Philippe Chantreau - Agreed. Gatekeepers keep down such nonsense as an "iron core sun", odd planetary alignments driving Earth climate, little green men, and so on. Peer review checks for basic, credible evidence. I haven't seen any for the ENSO/global warming hypothesis, and I rather doubt such nonsense would make it into a peer-reviewed journal of any relevance or note.
  3. Bob Tisdale - ENSO cycles are (as shown in several posts above) a quite good match for detrended global SST's. Which indicates that that ENSO is not responsible for the trend itself.
  4. As anyone who remembers the big hair and shoulder pads of the 80s knows, Gatekeepers are complemented by Key Masters. Bob Tisdale seems to be approaching science with a rusty nail rather than anything resembling a key. Why am I reminded of the Stay Puft Marshmallow Man?
  5. I think this is one of the most interesting graphs of Reynolds SST data for this discussion: It is simply the weekly SST anomaly for various regions of interest to this discussion. It is presented without rescaling, rebaselining, or lagging or any other device that might conceal the vast differences of variability between the two regions. So presented it is immediately apparent just how variable the Nino 3.4 region is compared to other regions. You might think that that is just because it is a small area, and the larger areas contain sub-regions with contrasting trends that reduce the mean variability. However, one of those regions, (Indian Ocean Tropical, in orange) is the region of the Indian Ocean from 50 to 100 degrees East, and from 5 degrees North to 5 degrees South. That is, it occupies the same area, and the same latitude as the Nino 3.4 region, yet it has only 32.3% of the variability of the Nino 3.4 region. Clearly the Nino 3.4 region (and presumably other directly ENSO effected regions) are exceptionally variable relative to other regions of the world's oceans. Another way of saying that is that the region has a very high noise to signal ratio when it comes to detecting medium term trends. The same is true of the East Pacific, which is dominated by ENSO variations. We all know that when it comes to detecting long term trends, we want to focus on the signal, not the noise. If you do not, you will find yourself "going down the up escalator, and all sorts of other improbable contortions. That is not reason to avoid studying the Eastern Pacific SST, but it is reason to take care that you are not fooling yourself with noise to avoid looking at the signal. You can take several steps to avoid fooling yourself in that regard. You can check out statistical significance: This is a bit crude, but as the table shows, the increase in regional temperatures plus two standard deviations for Nino3.4 (1.52 C)and the East Pacific (0.4 C) comfortably exceeds the increase in Global SST anomaly (0.26 C). A proper analysis of the error of trend calculations taking into account auto-correlation and multi-decadal influences such as the PDO is likely to find (I suspect) that they do not differ significantly from the model predictions for the East Pacific of 0.42 and 0.44 C (as quoted by Tisdale). Be that as it may, the important point here is that Tisdale's hypothesis does not even pass the most rudimentary test in showing that the limited warming in the East Pacific is unexpected given global warming. An even more rudimentary test is to check that your analysis is robust with regard to endpoints, and hence is not just a function of short term fluctuations. In this case, we that ENSO dominates the region and is the source of the large fluctuations in temperature. Looking at the ENSO 3.4 index, we see that Tisdale's start point just happens to precede the second strongest El Nino event since 1950, and precedes a period note worthy for its lack of La Ninas; but that the end of the period is noteworthy for weak El Ninos and several strong La Ninas: This pattern fully accounts for the negative trend in the Nino 3.4 anomaly, and hence the flat trend for the Eastern Pacific. Is it, however, a consequence of the start point of the data? As it turns out, yes it is. Just preceding the start point was another period of strong La Ninas. Including that period in the data results in a warming East Pacific: It turns out that not only is the lack of warming in the East Pacific not statistically significant, its existence is an artifact of the choice of start and endpoints in the data. I assume this is not the result of conscious cherry picking. Tisdale's chosen data set just happens to start in 1981. But he should have been aware of the possibility that what he thought he saw was just an artifact of incomplete data, and checked longer time periods using other data. He was negligent at least. This leaves him in an awkward position. Tisdale has provided no physical basis for his theory. He is, therefore, recommending it to us soley on the basis of the statistically unusual nature of the data. But it turns out that the data is not statistically unusual after all. That leaves his theory with nothing to recommend it until he can provide us with a physical mechanism behind his theory.
  6. Sure, KR & Phillipe, but I strongly suspect that that type of gatekeeping is not what Bob is imagining, although I can't think of any examples that would supply evidence for such a thing -- unless one chooses to defend various methodologies attempted by Soon & Baliunas, Spencer & Braswell, or Watts et (a diminishing) al.
  7. Just swooping down to clarify a few things for Mr. Tisdale. To be accurate one should refer to the theory of anthropogenic warming or theory of human-induced warming, it is not correct to speak of the "hypothesis of anthropogenic warming". To illustrate using an example: Mr. Tisdale has a hypothesis, just like the Slayers of the Skydragon have (had?) a hypothesis. Now until Mr. Tisdale succeeds in convincing the scientists who specialize in this area that his ideas have merit, his idea will forever be destined to obscurity and be nothing more than a hypothesis on a climate "skeptic" or climate denier blog. As for his disappointing excuse not to pursue publishing his ideas in a journal, there is always "Principe Scientfic Intl.". But doing so would not meet the criterion for publishing in a reputable scientific journal. I would dare Mr. Tisdale to publish in J. Climate or JGR-A or GRL or Nature or Science, but then I would be guilty of very likely wasting the valuable time of the editors and busy scientists with Mr. Tisdale's well-intentioned, but misguided ideas. Anyhow, it is telling that he is not up for the challenge, instead invoking conspiracy theories rather than actually submitting a manuscript for review by experts in the field. On the following, I do not necessarily wholly disagree with Mr. Tisdale, however, scientists have been researching this and publishing their findings in highly respected journals for some time now: "It’s best to divide the oceans into logical subsets, because coupled ocean-atmospherics processes impact ocean basins in significantly different ways. Realistically, that’s the only way anyone can attempt to perform an attribution study on the warming of ocean heat content data--or sea surface temperature data." Here is a review of some relevant papers through time on this subject. Note that they all find compelling evidence that the long-term warming of the planet's oceans is primarily externally driven (that is it is primarily the result of higher greenhouse gas levels from human activities). They have found this using sea-surface temperatures, ocean heat content and even salinity. Moreover, they have found the anthropogenic signal both globally and over individual basins. In short, the long-term warming of the planet's oceans is primarily in response to rising greenhouse gas concentrations, not El Nino or ENSO. To wit: Sedláček and Knutti (2012,GRL). Two of their key findings: "Ocean warming of the last century cannot be explained by natural variability The warming signal is visible throughout the whole ocean" Gleckler et al. (2012, Nature Climate Change), "Our detection and attribution analysis systematically examines the sensitivity of results to a variety of model and data-processing choices. When global mean changes are included, we consistently obtain a positive identification (at the 1% significance level) of an anthropogenic fingerprint in observed upper-ocean temperature changes, thereby substantially strengthening existing detection and attribution evidence." From Pierce et al. (2012), "We find that observed changes are inconsistent with the effects of natural climate variability, either internal to the climate system (such as El Niño and the Pacific Decadal Oscillation) or external (solar fluctuations and volcanic eruptions). However, the observed changes are consistent with the changes expected due to human forcing of the climate system." From Santer et al. (2008, PNAS), "For the period 1906–2005, we find an 84% chance that external forcing explains at least 67% of observed SST increases in the two tropical cyclogenesis regions. " From Pierce et al. (2006, J. Climate), "The observed sampling of ocean temperature is highly variable in space and time, but sufficient to detect the anthropogenic warming signal in all basins, at least in the surface layers, by the 1980s." From Barnett (2005, Science) "A warming signal has penetrated into the world's oceans over the past 40 years. The signal is complex, with a vertical structure that varies widely by ocean; it cannot be explained by natural internal climate variability or solar and volcanic forcing, but is well simulated by two anthropogenically forced climate models. We conclude that it is of human origin, a conclusion robust to observational sampling and model differences. " From Barnett et al. (2001, Science) "Further, the chances of either the anthropogenic or observed signals being produced by the PCM as a result of natural, internal forcing alone are less than 5%. This suggests that the observed ocean heat-content changes are consistent with those expected from anthropogenic forcing, which broadens the basis for claims that an anthropogenic signal has been detected in the global climate system." Then again, I do not expect Mr. Tisdale to be swayed by the overwhelming evidence against his idea. But maybe he will surprise us. Now the roaring forties beckon.
  8. Albatross - Thank you, a very informative post. The timings, patterns, and energies observed (in all ocean basins) point to the theory of anthropogenic warming, and contradict the hypothesis of natural variations and cycles. If Bob Tisdale wishes to argue his hypothesis he's going to have to show that his hypothesis matches all of those observations, and in addition provide a supportable mechanism. In particular, he's going to have to address these existing works, demonstrate that they have errors, and how his hypothesis gives a better explanation for observations (not to mention showing why the expected GHG warming does not occur in his framework). You simply cannot put up a new hypothesis without demonstrating shortcomings in the existing theories - not if you want to be taken seriously. As with Albatross, I don't expect Tisdale to be swayed by the evidence either; he has a great deal invested in his hypothesis. But I'm willing to be surprised.
  9. Tom Curtis @73 says: "As an aside, I was considering the first of your graphs reproduced by Kayell here, which I now realize is not lagged (final clause added in edit). Correctly lagged it looks like this: " Please don't misrepresent the graph you're showing as equal to mine, only lagged. Your global graph is not based on my global, adjusted down in 1987-88 and 1998-99 only. Your graph is based on Sphaerica's randomly adjusted one. This is quite easy to see. The justification for MY two points of adjustment is self-explanatory; just look at (compare) the original data. The justification for Sphaerica's adjustments is nonexistent.
  10. Kayell, You clearly fail to understand. Tom's graph is not based on either of our methods. It is properly detrended using a linear term. The justification for your two points is no better or worse than mine. It is arbitrary, unless you can submit an objective mathematical formula that was used to derive your points, as well as a valid physical justification (i.e. a mechanism whereby El Niño heats the atmosphere in step-changes in only those two instances) for doing so, both of which are lacking in your discussion. Tom's method, on the other hand, simply assumes a generally linear warming (not perfectly accurate, no, but it's the right way to do things when it is not entirely possible to separate the noise from the signal). Tom's method is the way it should be done, it makes no assumptions without physical cause, is entirely objective, and produces a result superior to yours/Tisdale's. So why, then, would we consider your/Tisdale's theory as anything more than playing games with graphs?
  11. Kayell @84, I apologize for inadvertently misrepresenting your technique; although it feels strange to apologize for assuming somebody has used a valid rather than an arbitrary rescaling. Having reread your post @35 (which I had previously only skimmed, I now see where you wrote:
    "When I 'detrended' the global SSTA curve in the graph above, I didn't use a statistical tool to remove a general upward trend. All I did was to pull it down at two (2) short sections: two datapoints in the last half of 1987 (July and November) and one datapoint in the beginning of 1999 (January)."
    Would you please inform me the magnitude of the downward ajustment for each of the three months?
  12. Kayell, Your quote of William Briggs came from his post here, but I don't think he meant it the way you used it. Considering what he said in the rest of his post, I think his point is that if you are claiming that the trend is upwards, you don't have to use a linear model to make that claim. Whether the claim is a valid one is an entirely different matter. I don't fully agree with what he said, but the example he used is an excellent example as why one has to be very careful drawing patterns out of a noisy time series (BTW ENSO is noise when you are looking at multi-decadal trends). He artificially generated an artificial time series with zero trend with random noise: Yet if you fit a trend line it yields a statistically significant result. Now my question to you is, if you just eyeball the graph and claim that there is an increase till 2005 and then decrease from there, is it a valid claim? If you claim that there is a step, you at the bare minimum have to run some statistical testing as a sanity check. If your assertion passes a statistical test, we can then proceed with caution. If does not, there is no reason for it to be taken seriously. ############################ Now that I think about it a bit more, I think there is a much bigger problem. Your basis for shifting the global SSTA at those two points is based on your arguement that "extra heat piled up globally after an El Niño and during the transition to the first following La Niña", which you supported with the animation, that supposedly shows the "extra heat globally". The problem is this: since you are plotting a scaled global temperature anomalies and a regional temperature anomalies, you can't even interpret the difference between the two as a temperature difference because one of the quantities is scaled, let alone extra heat.
  13. You have to love Bob Tisdale complaining about the 'gatekeepers' of science ... in response to an opening post that starts by discussing the failings of McLean et al who published in JGR!! Bob, are you saying that your science is not even up to the standard of McLean et al, a classic example of science being entirely open to the so-called skeptics? And for the umpteenth time, where is the heat coming from? And why do you persist in selecting favoured subsets of the data, rather than consider the full body of data? Your cherry-picks may be more elegant than the "it's not warmed since 1998" crowd, but they are still cherry-picks.
  14. To all who have commented in response to my appearance here at SkepticalScience: You’ve not answered my very basic questions. In my opening comment (40) here, I presented some graphs and asked questions of you. The first graph was for the East Pacific, which shows no warming over the past 30 years. I asked, Why hasn’t the East Pacific warmed? IanC has attempted to explain why it has not warmed using an abstract form of sea surface temperature. He’s making the effort. Bravo, for that. The third graph was the detrended sea surface temperature anomalies for the Atlantic, Indian, and West Pacific, which I referred to as the “Rest of the World.” It shows four periods when the Rest-of-the-World data diverges from the ENSO index (the scaled NINO3.4 sea surface temperatures [scaling factor 0.12 and lag 6 months). The two divergences in green are obviously the effects of El Chichon and Mount Pinatubo, but the divergences in brown are ENSO-related. The sea surface temperatures for the Rest of the World do not cool proportionally during the La Niña events of 1988/89 and 1998-2001. Everyone here has avoided the discussion of that graph. That’s the big ticket item, and it’s blatantly obvious why it’s important. Up through comment 67, I have replied to your questions and comments, yet no one here has replied to that question from comment 40. It’s time for you to catch up with me. You all are running way behind in the QnA. So I’ll ask the question again: Why does the detrended [Rest of the World] data diverge from the ENSO index during the 1988/89 and 1998/99/00/01 La Niñas? The ball is in YOUR court. Unless YOU can explain those divergences, there is no reason to continue this conversation. If and when you explain them, I’ll be happy to respond to all of the questions you’ve presented. I’ll check back every couple of days. Regards PS: skywatcher says: “You have to love Bob Tisdale complaining about the 'gatekeepers' of science…” I wasn’t complaining, skywatcher. I was being realistic. There is a difference.
  15. Bob Tisdale: Why should anyone here feel obliged to respond to your nonsense? As far as I can see your questions are an attempt to side-step sea surface temperature trends as well as increasing ocean heat content. I mean, come on. Your graph of "Detrended Rest-of-World SST Data Disagrees with The Warming of SST Anomalies As Portrayed By AGW Proponents" [SST abbreviated by me]? Of course it disagrees - you detrended the SST data. As far as divergence between SST behaviour and ENSO goes, one would only expect complete agreement between SSTs and ENSO if ENSO were the sole driver of SSTs. But the fact that there is an upward trend in SSTs puts the boots to such a belief: other factors also drive SST behaviour. So, if anything, we would expect divergence from ENSO from time to time. Tom Curtis' post at #80, in the meantime, puts the boots to your claim that the East Pacific "hasn't warmed":
    It turns out that not only is the lack of warming in the East Pacific not statistically significant, its existence is an artifact of the choice of start and endpoints in the data. [Emphasis original.]
    So how is one to characterize your claim "no one here has replied to that question from comment 40" except as refusal, whether through inability or unwillingness, to read others' posts on this thread?
  16. Bob says he's answered all questions put to him here. That's actually not true. He's been asked twice by a couple of different people to explain a key feature of his argument and so far has not replied.
    46 3: (perhaps most importantly) what is the energy source that allows the oceans to drive atmospheric temperature changes while themselves warming on a global scale? Where is the energy coming from, Bob? 70 Where is the energy required to produce net warming of the entire global ocean along with the atmosphere coming from?
    Bob, please just show us how a mass (global ocean+air) can increase in temperature without energy being added to it. Or from another perspective having to do with what our instruments tell us: Is global warming real or not?
  17. Bob, We didn't even get anywhere with the first question, why move on to the second? Doing so will just make the discussion intractable when we haven't even finished the first point. Let's recap: You @40: Why hasn't east pacific warmed? Me @41: Perhaps its internal variability such as PDO You @ 42: PDO can't be because the index exaggerates variability and the is inversely related to the N. pacific residual, and the dominant component is the N pacific Me @ 48: Here's evidence that PDO is a basin-wide mode, and the response in the east is the right order of magnitude to explain the lack of trend. You @ 52: No it can't be basin wide. PDO index doesn't represent SSTA because it is inversely related to the N. pacific residual. Me @56: Shows more evidence of PDO being a basin wide mode, shows PDO index can represent SSTA when interpreted in conjunction with the EOF, I even showed how you can get the scaling factor you found, and why PDO index is inversely related to N pacific SSTA. You @62: PDO index is standardized and exaggerates variability. PDO is inversely related to North pacific SSTA. PDO is index is abstract, why not use NINO3.4? Up to this point, all three of your counters consist of repeating what you think is right. You have not cited any evidence that your understanding is correct. You have not cited one single journal article that PDO does not impart an inter-decadal variability in the east Pacific. Whether PDO index is abstract is irrelevant, and frankly your complaints about the index are just red-herrings. You have avoided the real question: is there an inter-decadal variability that can explain the lack of warming in the east? To me you are just avoiding the issue, and it is not even clear if you've spent time reading and thinking about what I said, because if you had, you will not be repeating the same set of arguments three times. Look, it is not hard. If you think I have a point, that PDO is a viable answer to your first question, say you'll have to think about it and then we move on to your second question. If you think I'm wrong, explain, with new evidence, why I am wrong, and PDO is not a plausible explanation for the trend in E. pacific. Don't use a lack of discussion on your second question as an excuse to avoid discussing responses to your first question. BTW, I think you lost track of where the ball is. You served, I returned serve. I have yet to see the ball coming back to my side of the court. All there is so far is complaints that the ball is too fuzzy, too hard, and there's no ball.
  18. A quick question for Bob Tisdale to clarify something about the nino/nina thing: are you arguing that SSTs respond more strongly to El Nino than to La Nina, i.e. that El Nino warms SSTs more than La Nina cools them?
  19. And, as Bob himself remarked earlier, we don't want to take anybody's words out of context. Skywatcher's full sentence about the complaining on "gatekeepers of science" was as follows: "You have to love Bob Tisdale complaining about the 'gatekeepers' of science ... in response to an opening post that starts by discussing the failings of McLean et al who published in JGR!!" JGR being a serious journal, the kind that would definitely add some weight to Bob's argument if he submitted his work there and passed peer-review. Nonetheless, even if that happened, it would be met with healthy, scientific skepticism, as this is what's it's all about, after all; we all understand that peer-review is a minimum standard, not a golden one, and it is not infaillible.
  20. Following Kayell's complaint (@84), I have reproduced his "detrending" method using the weekly OHC data: For those wanting technical details, I adjusted each interval between Kayell's stated adjustment points to have a common mean. Transitions where spaced over five weeks with an equal change in each week to avoid introducing very large adjustments in a single week. Both the Nino3.4 and Global anomalies have been divided by their Standard Deviation. The rescaling makes the magnitude of variation consistent for comparison without pretending global fluctuations are much larger in degrees C than they actually are. Contrary to Sphaerica @74, although this method of detrending is arbitrary, it does not give a noticeably inferior fit to simple linear detrending:
    (Note, this graph is essentially the same as that in my post 76, except that it uses Standard Deviations rather than degrees C for the y-axis.)
    Indeed, if you look at the residuals - the difference between the scaled Nino 3.4 anomaly and the scaled Global anomaly in the two graphs, it is difficult to tell them apart: Of particular interest here is the yellow line, which shows the difference in the residuals between the linearly detrended and Kayell adjusted graphs. It shows a clear pattern of rising gradually with the linear detrending, with three abrupt shifts down from the adjustments following Kayell's method. The important thing to note is that the difference never exceeds (approximately) 0.5 Standard Deviations. That means the difference between the two methods is not statistically significant. That simple fact is devastating to Kayell's argument. Kayell (and Tisdale) argue that the data show step changes in the SST data, yet it is well known that the combination of a linear trend, noise and natural cycles can give the appearance of step changes where none exist: Consequently, when we see what may naively be interpreted as a step change, we need evidence that we are not simply fooling ourselves. That evidence, for Kayell (and Tisdale) is the ability to "detrend" the global SST anomaly by introducing three major shifts rather than by simply linear detrending. But as it turns out, there is not statistical difference between the two methods. Therefore, the ability to "detrend" by introducing step changes is not significant evidence. Indeed, it is worse than that. We can test the "fit" between the Nino3.4 and Global anomalies for the two different methods of "detrending". We can take the correlation, for example, although there are reasons to think it is not a suitable method for the comparison. Alternatively, we can take the Root Mean Squared Deviation: That's all the difference there is between the two methods of "detrending". The linear detrend scores (just) better in terms of Root Mean Square Deviation, but the Kayell Adjustment shows a whopping 0.0075 better correlation between Nino 3.4 and adjusted Global SST anomalies. And on that massive 0.0075 difference rests the entire claim of a step change in sea surface temperatures following the 97/98 El Nino. Colour me unimpressed. Of course, this is not a case where we are comparing the predictions of two physical theories with distinct predictions. Climate science clearly predicts an approximately linear trend in SST over the period of interest, as modulated by ocean cycles and noise. There is a substantial, well worked out physical theory predicting the result. What is more, there are known factors likely to lead to the appearance of a step change in the data. The Pinatubo eruption in the 1990s, and a weakening solar cycle coupled with a switch from El Ninos to La Ninas in the 2000s are, when coupled with global warming, perfectly adequate explanations for that appearance. In stark contrast, neither Kayell nor Tisdale have provided any physical theory predicting a step change. Consequently their only justification for believing one exists is statistical, ie, the 0.0075 point superior correlation when using the Kayell Adjustment compared to a linear detrending. So once again we find that Kayell and Tisdale have no evidence to support their claims, and no theory to justify making them.
  21. @ Bob Tisdale: Do you agree, or disagree with the following statement? “Naturally occurring climate variability due to phenomena such as El Niño and La Niña impact on temperatures and precipitation on a seasonal to annual scale. But they do not alter the underlying long-term trend of rising temperatures due to climate change as a result of human activities,” said WMO Secretary-General Michel Jarraud. Source:2012: Record Arctic Sea Ice Melt, Multiple Extremes and High Temperatures, WMO Press Release No 966, Nov 28, 2012
  22. A quick question for Bob Tisdale to clarify something about the nino/nina thing: are you arguing that SSTs respond more strongly to El Nino than to La Nina, i.e. that El Nino warms SSTs more than La Nina cools them?
    It's obvious Philippe - ENSO is a bootstrap process, a magic ratchet or a magic pudding as I've noted elsewhere. However, I very much doubt that Tisdale will actually ever elucidate the thermodynamics of his claim. He's been asked here repeatedly, and many others of us have pressed him about it on multiple occasions over a year ago at WWWT, and there's never been a simple, straight explanation - or even a convoluted one for that matter. Having said that, I'd be most curious to hear Tisdale's response to your question.
    Response: [DB] Closed the italic hashtag; guessed as to its most likely location.
  23. 'I wasn’t complaining, skywatcher. I was being realistic. There is a difference." I agree that Bob is being realistic - the review process would make demands that I think Bob is unable to answer.
  24. I believe that the following graphic relates directly to our ongoing discussion with Tisdale. Image and video hosting by TinyPic Source: 2012: Record Arctic Sea Ice Melt, Multiple Extremes and High Temperatures, WMO Press Release No 966, Nov 28, 2012
  25. Got to love Dr Inferno. Of relevance to this thread, "Things That Can Be Blamed Instead" ... ENSO. Same way the Moon causes sea level rise. ...

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