No Evidence of Changes in ENSO Caused by Global Warming

Blogger “slimething” alerted me to the recent paper by Ray & Giese (2012) titled Historical changes in El Niño and La Niña characteristics in an ocean reanalysis. (Thanks, slimething.) Refer also to the post at The Hockey Schtick. Curiously, there’s no paywall. That is, the paper is not available for purchase, so all we’ve got to work with is the abstract:

The variation of El Niño Southern Oscillation (ENSO) events from the mid-nineteenth century until the beginning of the twenty-first century is explored using an ocean reanalysis. A comparison of the reanalysis with three sea surface temperature reconstructions shows that the timing of events is similar in all four products, however there are important differences in the strength and location of events. The difference between the reconstructions is sometimes larger than the difference between the reanalysis and a given reconstruction. These differences are larger in the first half of the record, a period for which there are relatively sparse observations. The reanalysis is used to explore decadal variability and trends in the frequency, duration, and propagation direction of ENSO events. There is considerable decadal variability of these ENSO characteristics with the time between events ranging from several months to ten years and the duration of ENSO varying from 5 to 27 months. As has been previously shown for the strength and location of ENSO there is little overall trend in the characteristics. Having a three dimensional representation of the ocean from the reanalysis allows exploration of subsurface changes during ENSO. An analysis of subsurface anomalies shows that during ENSO events the subsurface anomalies are highly correlated with the strength of surface anomalies over the 140 year period. Overall, there is no evidence that there are changes in the strength, frequency, duration, location or direction of propagation of El Niño and La Niña anomalies caused by global warming during the period from 1871 to 2008.

This is a great topic for a post, and there are lots of ways to show that there’s no evidence of an anthropogenic global warming component in ENSO, so I will present the discussion after the upcoming WUWT-TV special.

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About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
This entry was posted in CAGW Proponent Arguments, El Nino-La Nina Processes. Bookmark the permalink.

6 Responses to No Evidence of Changes in ENSO Caused by Global Warming

  1. Sean says:

    What I think is interesting is that a lot of seasonal forecasters use the state of the oceans for their predictions and there are times when they can make some extraordinarily accurate forecasts. From what I have read, the GCM’s do a very poor job of predicting ENSO, AMO or other water temperature distribution patterns and hence are terrible at regional forecasts. For me, this has always begged the question, do oceans drive the weather or does weather drive the ocean states. Since they are couple systems, it’s likely difficult to solve this chicken and egg question or the underlying mechanisms of the ocean’s cycles. The point I am trying to make, there are some who think the total ocean heat content (or sea level change) is the best gauge of the overall extent of climate change but could the ability to predict ENSO, AMO and other temperature distribution patterns by GCM’s the criterial by which they should be judged for estimating their effectiveness at making long term climate predictions?

  2. HR says:

    Thanks for this.

    It’s worth remembering that it was the extended El Nino conditions of the early 1990’s that produced a slew of papers on the possible link between AGW and ENSO change. They seemed to be confirmed by the 1998 super-ENSO, which sent the subject into the stratosphere. Problem is events since have failed to co-operate. So two events (and probably a co-operative climate model) lead to a bit of presumptive hysteria,, it seems only right that this should be corrected somewhat in the literature. It’s a shame the original hypers (Trenberth et al) aren’t the one’s to correct their own mistake. To me the whole history has the same ring to it as the future hurricane predictions, hype around a few events, and a climate model result leading to a false sense of what should be expected for the future.

  3. DB says:

    Bob, have you read the recent PNAS paper by Luo, “Indian Ocean warming modulates Pacific climate change”?
    http://www.pnas.org/content/early/2012/10/25/1210239109.full.pdf+html
    warmer Indian Ocean ==> stronger trade winds ==> more La Nina states

  4. Bob Tisdale says:

    Thanks for the link, DB. I wonder if they consider the possibility that the increase in La Nina events may be causing the increase in the Indian Ocean sea surface temperatures as well.

  5. DB says:

    They write in their introduction:
    “…exact factors contributing to the faster warming in the IO [Indian Ocean] remain unclear.”
    adding in the discussion section:
    “It is also known that Pacific signals that vary year to year strongly influence the IO climate. For example, the El Nino signal usually warms the IO; this helps to increase the Pacific trade winds and hence weaken the El Nino. As a result, the interannual tropical climate variations are influenced by the intrinsic interactions between the IO and the Pacific.”

  6. Bob Tisdale says:

    DB: And during La Nina events, more warm water then normal is transported via the Indonesian Throughflow into the Indian Ocean.

    Regards

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