It’s only taken two weeks to go from the blog posts shredding McLean et al to a paper submitted to the Journal of Geophysical Research. The authors are G. Foster, J. D. Annan, P. D. Jones, M. E. Mann, B. Mullan, J. Renwick, J. Salinger, G. A. Schmidt, and K. E. Trenberth and the abstract says:

McLean et al. [2009] (henceforth MFC09) claim that the El Niño/Southern Oscillation (ENSO), as represented by the Southern Oscillation Index (SOI), accounts for as much as 72% of the global tropospheric temperature anomaly (GTTA) and an even higher 81% of this anomaly in the tropics. They conclude that the SOI is a “dominant and consistent influence on mean global temperatures,” “and perhaps recent trends in global temperatures”. However, their analysis is incorrect in a number of ways, and greatly overstates the influence of ENSO on the climate system. This comment first briefly reviews what is understood about the influence of ENSO on global temperatures, then goes on to show that the analysis of MFC09 severely overestimates the correlation between temperature anomalies and the SOI by inflating the power in the 2-6 year time window while filtering out variability on longer and shorter time scales. It is only because of this faulty analysis that they are able to claim such extremely high correlations. The suggestion in their conclusions that ENSO may be a major contributor to recent trends in global temperature is not supported by their analysis or any physical theory presented in that paper, especially as the analysis method itself eliminates the influence of trends on the purported correlations.

Via Joe Romm and Gareth Renowden.

Comments

  1. #1 Barton Paul Levenson
    August 12, 2009

    cohenite posts:

    Ln CO2 accounted for 75% of the variance”

    Don’t think so;

    It isn’t up for debate, cohenite. Given the data I used, that’s the amount of variance accounted for. Want the math? Unless you can show that I calculated wrong, the figure stands. Deal with it.

  2. #2 MAB
    August 12, 2009

    David,

    >particularly as the period we are looking at, unlike your data is not one full cycle.

    Wouldn’t a part cycle look like a step?

    Also, can you clarify what you mean by SOI+cSOI accounting for variance? Specifically, is this double counting SOI?

  3. #3 Barton Paul Levenson
    August 12, 2009

    I was able to accumulate figures for all of Hadley Centre CRU temperature anomalies, ln CO2, Svalgaard’s TSI reconstruction, SOI, the PDO index, and Mann’s extension of Lamb’s Dust Veil Index for the years 1900-1995 (N = 96). A regression of temperature anomaly on the others accounted for 70% of the variance. All the terms were significant except for PDO (t = 1.3). Carbon dioxide accounted for 61% of the variance, so sunlight, SOI, and DVI together only account for 9%. If anyone wants I’ll send them the data I used.

  4. #4 Dave R
    August 12, 2009

    David Stockwell:

    I would question how well understood CO2 forcing is when the IPCC range of sensitivity is between 5 and 1.5 per doubling.

    The forcing from CO2 in the IPCC AR4 is 1.66 +/- 0.17 W/m^2.

    Climate sensitivity to a forcing is independent of the nature of the forcing, so the uncertainty in the sensitivity value cannot tell us anything about how well understood a particular forcing is.

    I don’t know where you got your figures for sensitivity from but they are not the ones in the IPCC AR4, which has 2 to 4.5 K per doubling with a best estimate of 3 K.

  5. #5 Bernard J.
    August 12, 2009

    David Stockwell.

    Leaving aside the question that both [James Haughton](http://scienceblogs.com/deltoid/2009/08/two_weeks_from_blog_post_to_pa.php#comment-1834249) and [myself](http://scienceblogs.com/deltoid/2009/08/two_weeks_from_blog_post_to_pa.php#comment-1829573) have asked, regarding how you discriminate between a ‘break’ and the superimposition of understood drivers of temperature, I remain curious about the ‘engine’ behind your suggestion of ENSO accumulation.

    I take it that your last paragraph in [#94](http://scienceblogs.com/deltoid/2009/08/two_weeks_from_blog_post_to_pa.php#comment-1834254) is a precis of your postulated mechanism. Assuming for the time being that your somewhat vague description is in fact repesentative of the ‘break’ mechanism, could you clarify whether you assume the presence of an inherent positive feedback, and if so, how it is governed, and how it is broken?

    I presume that you would include solar activity and/or astronomical cycles in your postulations, so how do they relate to the late 20th century breakings? What periodicities do you suggest are the maximum and minimum that might operate under such a mechanism, and what positive fluctuation over a mean global temperature would you suggest that ‘ENSO accumulation’ gives?

    Given that your mechanism must have operated for millenia prior to humans taking an interest in the goings-on of the atmosphere, what has recently changed in the ‘ENSO accumulation’ that has resulted in the [biotic and abiotic integration signals](http://www.nature.com/nature/journal/v453/n7193/abs/nature06937.html) that indicate that the warming observed over the last century or so is not typical over very much longer spans of time?

    Apparently (h/t [Mark Byrne](http://scienceblogs.com/deltoid/2009/08/plimer_chickens_out.php#comment-1834753)) one should suffix [one’s questions](http://www.guardian.co.uk/environment/georgemonbiot/2009/aug/12/climate-change-climate-change-scepticism) these day with:

    All assumptions must be justified and calculations and sources of information must be shown.

    but I am really just interested in the executive summary that indicates that there is indeed a solid foundation for described processes.

  6. #6 Dave Andrews
    August 12, 2009

    BPL,

    “I was able to accumulate figures for all of Hadley Centre CRU temperature anomalies”

    Problem is you don’t know the code behind how those figures were were calculated nor the historical provenance of them. So you have no way of knowing if they are accurate or not.

  7. #7 Michael
    August 12, 2009

    Yeah, and they probably came from an evil computer, which probably has been used for modeling hence invalidating anything I says it does.

  8. #8 Mark
    August 12, 2009

    > Yeah, and they probably came from an evil computer, which probably has been used for modeling hence invalidating anything I says it does.

    > Posted by: Michael

    Easy to check: just see if the Evil Bit is set…

  9. #9 Barton Paul Levenson
    August 13, 2009

    Dave Andrews posts:

    BPL: “I was able to accumulate figures for all of Hadley Centre CRU temperature anomalies”

    DA: Problem is you don’t know the code behind how those figures were were calculated nor the historical provenance of them. So you have no way of knowing if they are accurate or not.

    They correlate 97% with the NASA GISS figures, which are publicly available. Warming is also seen in the satellite (RSS and UAH) temperature readings, borehole readings, and assorted environmental effects from melting glaciers to earlier blooming dates for flowers. There’s no question that global warming is happening, nor in the shape of the warming data against time.

  10. #10 James Haughton
    August 17, 2009

    David and Anthony might want to consider [Tamino’s recent post](http://tamino.wordpress.com/2009/08/17/not-computer-models/) finding that SOI had no long-term effect.

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