Another Mickey Mouse Study Purports To Demonstrate That The Extraordinary Spike In GMST In 2023 Was 88% Due To El Nino

It gets better (or worse) by the day. HTDS (Hunga Tonga Derangement/Denial Syndrome) is a thing and it’s becoming firmly embedded in academia. I was alerted to this paper by a tweet from Ryan Maue on X:

AMO as it turns out contributed only a very modest amount to the warming in 2023. According to the authors of this study, El Nino was responsible for a whopping 88%.

MDV (multidecadal variability - including AMO) and SCT (the secular trend - allegedly 100% due to man-made global warming) contributed very little.

The authors write:

This is a neat trick. The authors are basically saying that because, from 2010-2022, the correlation between annual variability in global temperature (ANV) and Nino 3.4 was 0.61, therefore, by deduction, ANV (and hence El Nino) must have contributed 88% to the temperature spike in 2023! This is circular reasoning and you have been conned. Why?

For a start, it’s pretty obvious from looking at Fig. 2(b) that whereas in 2016 (a super strong El Nino year) Nino 3.4 (black line) correlated only moderately with ANV (pink bars), but sharply dominated the GMST increment, in 2024, the situation reversed, with ANV correlating very strongly with Nino3.4 but with ANV also exceeding NINO 3.4 with its contribution to the GMST increment. This doesn’t make sense.

Also, perhaps more importantly, because the Nino3.4 index which the authors claim is correlated to ANV is an average taken over one year and does not account for monthly variability (as I have pointed out on numerous occasions, the 2023 global temperature spike started atypically in June, when the El Nino was in its infancy) the conclusion that El Nino played a major role in the warming in 2023 is very suspect. The Rydpal 2018 paper cited by the current authors as justification for their correlation between Nino 3.4 and ANV makes the following very clear:

The data were analyzed with annual resolution, including the AMO. All datasets were downloaded with monthly resolution, and from these monthly data, annual averages were computed by averaging over calendar years. However, the AMO monthly data set used here is really an 11-year moving average. The reason for this choice is that the AMO is a multidecadal oscillation, i.e., its dynamics involve time scales longer than a decade. The variability of the AMO index on an annual scale is not related to this mode. This variability is comprised of regional climate noise uncorrelated with the GMST and possibly, some variability that contributes to the GMST and is correlated with it. If we include this latter variability as part of a predictor in the regression analysis, we, in effect, use the GMST as a predictor of itself, and this may spuriously enhance the weight of its footprint. It turned out, however, that using unsmoothed data made almost no difference. This indicates that annual scale fluctuations in the AMO-index are essentially uncorrelated with the GMST and therefore, do not have any significant effect on the results of the regression analysis.

The same reasoning cannot be applied to ENSO because it is an interannual mode. Since ENSO also has a significant seasonal structure, one could argue that monthly resolution in the analysis would have been more appropriate. However, the inclusion of seasonal variability would add many complications in the interpretation of the analysis and was not the kind of variability that we seeked to explain. The important thing was that the annual means were all computed the same way for all data.

The authors’ conclusions are made all the more absurd by the fact that they admit that the monthly observed global temperature anomalies in 2023 were unique and very dissimilar to 2016 (a super El Nino year):

Not a single mention of course of the volcano which shall not be mentioned anywhere in the paper. Again, I have to ask the question: why the desperate and concerted attempt to exclude Hunga Tonga from any role in the unique warming spike of 2023? Is it mass psychosis or an organised, deliberate effort. This latest attempt is a pretty poor effort though, to be honest.