I’ve moved to WordPress. This post can now be found at The Relationship Between ENSO And Global Surface Temperature Is Not Linear###############
The first part of this post is a rehashing of points made in earlier posts here and at WattsUpWithThat, including “Multiple Wrongs Don’t Make A Right, Especially When It Comes To Determining The Impacts Of ENSO”, and “Regression Analyses Do Not Capture The Multiyear Aftereffects Of Significant El Nino Events.” I will keep repeating the message with each new paper that attempts to perpetuate the misconceptions, or misunderstandings, or misinterpretations of ENSO until the message gets through.
The point introduced in this post: The message has landed in at least one paper, but more on that in the Closing.
Expect to find a repeat of this message as soon as the Journal of Climate publishes the 2009 Thompson et al paper “Identifying signatures of natural climate variability in time series of global-mean surface temperature: Methodology and Insights.” It also fails to account for the long-term cumulative effects of ENSO on Global Surface Temperature.
Lean and Rind in their 2009 paper “How Will Earth’s Surface Temperature Change in Future Decades?” make a common error. Link to Lean and Rind (2009):
And there are many other papers that err in the same way. These include:
Foster et al (In Press) “Comment on ‘Influence of the Southern Oscillation on tropospheric temperature’” JOURNAL OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/
Lean and Rind (2008) “How Natural and Anthropogenic Influences Alter Global and Regional Surface Temperatures: 1889 to 2006” [GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L18701, doi:10.1029/2008GL034864, 2008].
Santer, B.D., Wigley, T.M.L., Doutriaux, C., Boyle, J.S., Hansen, J.E., Jones, P.D., Meehl, G.A., Roeckner, E., Sengupta, S., and Taylor K.E. (2001), “Accounting for the effects of volcanoes and ENSO in comparisons of modeled and observed temperature trends,” J. Geophys. Res., 106, 28033–28059.
Thompson, D. W. J., J. J. Kennedy, J. M. Wallace, and P. D. Jones (2008), “A large discontinuity in the mid-twentieth century in observed global-mean surface temperature,” Nature, 453, 646–650, doi:10.1038/nature06982.
Trenberth, K.E., J.M.Caron, D.P.Stepaniak, and S.Worley, (2002), “Evolution of El Nino-Southern Oscillation and global atmospheric surface temperatures,” J. Geophys. Res., 107 (D8), 4065, doi:10.1029/2000JD000298
Wigley, T. M. L. (2000), “ENSO, volcanoes, and record-breaking temperatures,” Geophysical Res. Lett., 27, 4101–4104.ENSO, volcanoes and record‐breaking temperatures
All of these papers assume that the relationship between ENSO and Global Surface Temperature is linear. Lean and Rind (2009) present this assumption in their Figure 1, which is Figure 1 of this post.
Note how the ENSO signal in Cell B of Figure 1 is fundamentally a scaled-down version of the Multivariate ENSO Index or MEI. Lean and Rind note the use of the MEI, “The multivariate ENSO index, E, is a weighted average of the main ENSO features contained in sea-level pressure, surface wind, surface sea and air temperature, and cloudiness [Wolter and Timlin, 1988].” The other papers noted above use others ENSO indices such as Southern Oscillation Index data, NINO3.4 or NINO3 SST anomalies, or Cold Tongue Index SST anomalies as their ENSO reference, and they all make the same erroneous assumption.
The assumption made is that the relationship between ENSO and Global Surface Temperature is linear. It is not. There are residual effects of significant El Nino events, like those in 1986/87/88 and 1997/98. These residual effects create upward step changes in Global Surface Temperatures, Figure 2, that are seen as divergences between the ENSO signal and Global Surface Temperatures. These divergences are mistaken for the impacts of Anthropogenic influences.
As noted in Figure 2, these step changes are easily seen in two datasets. The first is the SST anomalies of the Eastern Indian and Western Pacific Oceans, Figure 3.
The area represented by the East Indian and West Pacific Ocean SST anomalies (the black curve in Figure 3) is shown in Figure 4. The coordinates are 60S to 65N, 80E to 180. It occupies a significant portion of the world oceans, in the range of 25 to 30% of global sea surface from 60S to 65N.
Refer to the following posts for further information:
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2
The second dataset these step changes in response to the 1986/87/88 and the 1997/98 El Nino events can be seen in are the TLT anomalies of the Mid-to-High latitudes of the Northern Hemisphere, Figure 5. The 1986/87/88 and 1997/98 El Nino events are highlighted in the Hovmoller.
Refer to my post:
“RSS MSU TLT Time-Latitude Plots...Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone”.
The myths of Anthropogenic Global Warming are maintained by the continued misrepresentation of the impacts of ENSO on Global Surface Temperatures. But as noted in the Introduction, at least one paper, Stockwell and Cox (Submitted) “Comment on ‘Influence of the Southern Oscillation on tropospheric temperature’ by J. D. McLean, C. R. de Freitas, and R. M. Carter”, has proposed an alternate explanation.
Link to abstract:
Stockwell and Cox write in the abstract, “We demonstrate an alternative correlation between the El Nino Southern Oscillation (ENSO) and global temperature variation to that shown by McLean et al. . We show 50% of the variation in RATPAC-A tropospheric temperature (and 54% of Had-CRUT3) is explained by a novel cumulative Southern Oscillation Index (cSOI) term in a simple linear regression. We review evidence from physical and statistical research in support of the hypothesis that accumulation of the effects of ENSO can produce natural multi-decadal warming trends. Although it is not possible to reliably determine the relative contribution of anthropogenic forcing and SOI accumulation from multiple regression models due to collinearity, these analyses suggest that an accumulation ratio cSOI/SOI of 4:8 +/- 1:5% and up to 9 +/- 2% is sufficient for ENSO to play a large part in the global mean temperature trend since 1960.”
In time, maybe (maybe not), the true nature of ENSO will be accounted for by climate scientists in their analyses and GCMs. Until that time, I will continue to repeat what I’ve documented in numerous ways. The relationship between ENSO and global surface temperature is not linear.
H/T to David Whitehouse who noted in his post Forecasting the Earth’s Temperature that Lean and Rind (2009) had been published.