A Memo To Hansen and Sato

Guest commentary by Bob Tisdale

Date:August 21, 2011

Subject:A Request About Your El Niño Predictions And A Question About Anthropogenic Global Warming

To: James E. Hansen and Makiko Sato

Dear Makiko and James:

I am writing to you via my weblog with a request and a question. First, the request: Please stop predicting El Niño and Super El Niño events. Your track record is very poor. I, like many people who study ENSO, hope for extreme El Niño events, but when you predict a strong El Niño, a La Niña starts to evolve, and when you predict a “Super El Niño”, a mild El Niño comes to pass. Two examples come to mind:

Your March 27, 2011 mailing Perceptions of Climate Change was published at a number of websites, including Climate Story Tellers and Truthout. It included the following prediction of an El Niño event for the 2011/12 ENSO season:

Sometimes it is interesting to make a bet that looks like it is high risk, but really isn’t. Such a bet can be offered at this point. The NOAA web pages giving weekly ENSO updates predict a return to ENSO–neutral conditions by mid–summer with some models suggesting a modest El Nino to follow. We have been checking these forecasts weekly for the past several years, and have noted that the models almost invariably are biased toward weak changes. Based on subsurface ocean temperatures, the way these have progressed the past several months, and comparisons with development of prior El Niños, we believe that the system is moving toward a strong El Niño starting this summer. It’s not a sure bet, but it is probable.

Summer is well past its midpoint. And weekly NINO3.4 Sea Surface Temperature (SST) anomalies for August 10, 2011, based on the Reynolds OI.v2 dataset you use in your GISS Land-Ocean Temperature Index, are approaching the threshold of La Niña conditions, Figure 1.

Figure 1

Note also that the NOAA models included in the ENSO updateyou referenced (now dated August 15, 2011) are forecasting La Niña conditions. Refer to Figures 2 and 3.

Figure 2

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Figure 3

And the majority of the other ENSO models are forecasting ENSO neutral conditions, Figure 4.

Figure 4

Based on the spread of model outputs, ENSO events are apparently difficult to forecast even in mid August, so there’s still a remote possibility that your prediction may come true, but right now, NINO3.4 Sea Surface Temperature observations are clearly pointing in the opposite direction.

Regarding Super El Niño events, let’s drop back a few years. In the draft of a paper titled Spotlight on Global Temperature dated March 29, 2006, you and a few of your associates predicted a “Super El Niño” for the 2006/07 ENSO season. (Thanks to DeSmogBlog for posting and maintaining the copy of the draft.) To refresh your memory, here’s what you wrote 5 years ago:

SUPER EL NINO IN 2006-2007? We suggest that an El Nino is likely to originate in 2006 and that there is a good chance it will be a ‘super El Niño’, rivaling the 1983 and 1997-1998 El Ninos, which were successively labeled the ‘El Nino of the century’ as they were of unprecedented strength in the previous 100 years (Fig. 1 of Fedorov and Philander 2000). Further, we argue that global warming causes an increase of such ‘super El Ninos’. Our rationale is based on interpretation of dominant mechanisms in the ENSO (El Nino Southern Oscillation) phenomenon, examination of historical SST data, and observed Pacific Ocean SST anomalies in February 2006.

Please refer to Figure 5, which is a longer-term graph of the monthly Reynolds OI.v2-based NINO3.4 SST anomalies. You’ll note that I’ve indicated the 1982/83 and 1997/98 “Super El Niño” events. I’ve also marked the 2006/07 “Not-So-Super” El Niño, and the difference between the two, which results from your Not-So-Super Prediction.

Figure 5

If you’re not aware, there are many people who mistakenly believe that you are using your GISS Model-E General Circulation Models to make these erroneous predictions of strong and super El Niño events. I don’t feel it’s my responsibility to advise them that you are basing your predictions on your observations of climate data, not on your models, which as shown in Animations 1 and 2 do not appear model ENSO very well, if at all. Animations 1 and 2 are gif animations of time-series graphs that compare the observed NINO3.4 Sea Surface Temperature anomalies, which, as you are aware, are a commonly used index of the frequency and magnitude of ENSO events, to those hindcast by the GISS Model-EH and Model-ER.

Animation 1

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Animation 2

Your Model-EH and -ER, like other General Circulation models employed as future climate projection tools by the IPCC, do not come close to matching the frequency, magnitude, and duration of ENSO events. All three are very important when attempting to reproduce the instrument temperature record (and when trying to project future climate scenarios), since they dictate when and how much:

– heat is released from the tropical Pacific to the atmosphere, where it alters climate globally,

– warm water is distributed from the tropics toward the poles on the sea surface and below the surface of the oceans,

– warm water is created through coupled decreases in cloud cover and increases in visible sunlight over the tropical Pacific for use in the next ENSO event.

And now for my question: Where’s the Anthropogenic portion of the rise in Global Sea Surface Temperature anomalies during the satellite era? I can’t find it. I have been studying Sea Surface Temperature anomaly data for a number of years, and I cannot find any evidence of an anthropogenic component in Sea Surface Temperature Anomaly data. I’m referring to the satellite-era Reynolds OI.v2 Sea Surface Temperature dataset you use in your GISS Land-Ocean Temperature Index (LOTI) data. Animation 3 provides a basic introduction to what I have found.

Animation 3

Before you reply, please study two posts I’ve published recently:

ENSO Indices Do Not Represent The Process Of ENSO Or Its Impact On Global Temperature,

And:

Supplement To “ENSO Indices Do Not Represent The Process Of ENSO Or Its Impact On Global Temperature”.

They will provide a few answers to your initial thoughts.

I’m not sure if you’re aware of this, but many people outside of the climate science community have basic understandings of the process of ENSO. They realize that the warming and cooling of the central and eastern tropical Pacific during El Niño and La Niña events represent only a small portion of the processes that occasionally distribute vast amounts of heat from the tropics toward the poles, and they understand ENSO not only distributes heat through the atmosphere, but also within and on the surface of the oceans. They understand that the process of ENSO cannot be represented by a number in an ENSO index. Because of that, they understand the erroneous assumptions in the climate studies such as Fyfe et al (2010) “Comparing Variability and Trends in Observed and Modelled Global-Mean Surface Temperature” and Thompson et al (2008) paper Identifying Signatures of Natural Climate Variability in Time Series of Global-Mean Surface Temperature: Methodology and Insights. Those incorrect assumptions are carried over to blog posts such as Global trends and ENSO by your associates over at Real Climate. All portray ENSO as naturally occurring noise within the surface temperature record that can be removed through linear regression or through simple models that use an ENSO index to provide similar results. I have provided detailed explanations, illustrations, and animations in the above linked post (ENSO Indices Do Not Represent The Process Of ENSO Or Its Impact On Global Temperature) that illustrate the errors in these efforts.

In fact, as I noted in that post, the recent Compo and Sardeshmukh (2010) paper “Removing ENSO-Related Variations from the Climate Record” appears to be a step in the right direction. They write:

An important question in assessing twentieth-century climate is to what extent have ENSO-related variations contributed to the observed trends. Isolating such contributions is challenging for several reasons, including ambiguities arising from how ENSO is defined. In particular, defining ENSO in terms of a single index and ENSO-related variations in terms of regressions on that index, as done in many previous studies, can lead to wrong conclusions. This paper argues that ENSO is best viewed not as a number but as an evolving dynamical process for this purpose.

But Compo and Sardeshmukh also missed a very important part of ENSO. They overlooked the significance of the huge volume of warm water that is left over from El Niño events and failed to account for its contribution to the rise in global Sea Surface Temperature anomalies.

In closing, I, like you, look forward to the next strong or Super El Niño. I believe, though, we have different interests at heart. You appear to hope for one so that you can continue to piggyback your hypothesis of Anthropogenic Global Warming on its multiyear aftereffects. I hope for a Super El Niño because the ARGO buoys are in now place, and it should be possible now to better track how the oceans distribute the warm water that’s left over from Super El Niño events.

Sincerely,

Bob Tisdale