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Tuesday, September 15, 2009

El Nino Events Are Not Getting Stronger

I’ve moved to WordPress.  This post can now be found at El Nino Events Are Not Getting Stronger
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The Texas A&M press release in the WattsUpWithThat post “Possible Linkage between the 1918 El Niño and the 1918 flu pandemic ?” stated that “some researchers” continued to believe that global warming was causing stronger El Nino events. Link to press release:
http://dmc-news.tamu.edu/templates/?a=8028&z=15

Quote from it: “Giese adds, ‘The most commonly used indicator of El Niño is the ocean temperature anomaly in the central Pacific Ocean. By that standard, the 1918-19 El Niño is as strong as the events in 1982-83 and 1997-98, considered to be two of the strongest events on record, causing some researchers to conclude that El Niño has been getting stronger because of global warming. Since the 1918-19 El Niño occurred before significant warming from greenhouse gasses, it makes it difficult to argue that El Niños have been getting stronger.”

HOWEVER

Not to discount the work by Giese et al: a quick look at a graph of NINO3.4 SST anomalies that includes the 30 years before 1900, Figure 1, reveals that there were two comparably sized “Super” El Nino events in 1877/78 and 1888/89.
http://i25.tinypic.com/259v9si.png
Figure 1

Link to the preprint version of Giese et al (2009) “The 1918/1919 El Niño”:
http://www.cdc.noaa.gov/people/gilbert.p.compo/Gieseetal2009.pdf

SOURCE

HADISST Anomaly data is available through the KNMI Climate Explorer:
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere

9 comments:

John said...

Hi Bob (guess what, it's me again!) -

How do these earlier "Super" El Ninos fit in with your step change analysis? Wouldn't we expect similar results from those El Ninos?

What is giving the El Ninos of the past 30 years the step change effect of temperatures?

Bob Tisdale said...

John: The data becomes less reliable (and sparse) before 1940 that it's hard to determine if the step changes occurred during the warming period from the 1910s to the 1940s. Before that, it's even tougher.

Keep in mind, too, that there was a lot more explosive volcanic activity the late 1800s. That would have counteracted the El Nino events.

BTW, I didn't forget to reply to your earlier comment about the AMO. I thought I had written down the right thread, but I can't find it. Regardless, I've got about 24 papers (pdfs of studies) in my AMO file. I don't know that one's better than the other.

Google "Atlantic Multidecadal Oscillation", then click on the "view as HTML" to see if the abstract covers any topics you're interested in.

Regards

John said...

Thanks for the answer - I assumed it would be along those lines. Bucket measures can only give you so much detail.

If the data is indeed even accurate for Nino 3.4 in the past, it is very interesting to see that it really appears to not have varied substantially in size or frequency over the years when viewed from the birds eye.

By any chance have you plotted an anomaly trend line for this data? I obviously would never ask you to do work I could theoretically do myself, but if you've done it, I'd be curious to know the result. I've seen maps purporting the idea of warm/cold PDOs and their impact on frequency (which I've read your posts on), but I don't think I've seen a post on the anomaly trend for this long a time scale for this data set. I could be wrong.

It's a shame our ancestors couldn't have kept more concrete records. :)

Bob Tisdale said...

The linear trend is pretty flat, 0.17 deg C/Century.
http://i28.tinypic.com/whk4g3.png

John said...

Hi Bob -

On a semi-related topic. I noticed your post on WUWT that based on the subsurface temperatures this El Nino "may just be getting started" but I also recall a post by you on Lucia about questioning where the warmth would come from based on several criteria you listed.

I know you don't like to do predictions, but those seem to contrast? Are you simply presenting both arguments, or are you leaning one way or another?

I, for one, have no desire to see another large El Nino lead to a step change again. :)

climatechange1 said...

Hi Bob,
As you know, the 86/7 and 97/8 El Ninos were unique because of the La Ninas that followed them. Let us assume that it was the following La Ninas that redistributed the heat poleward, creating the observed SST step changes. Could it be possible that the 08-09 La Nina could have released heat from the El Ninos of the past decade?
The reason I ask this is because recent SST in the North and South Pacific have increased dramatically and have not recovered. Especially in the North Pacific, SST suggest something unique is occuring. I think it may be another step change.

Carl

Bob Tisdale said...

John: You wrote, "but I also recall a post by you on Lucia about questioning where the warmth would come from based on several criteria you listed."

Can you identify the thread at Lucia's?

John said...

Hi Bob -

It was here: http://rankexploits.com/musings/2009/el-nino-report-models-still-predicts-moderate-to-strong/#comments

But now that I re-read it, I think you may have been supplying reasons FOR an increasing El Nino, not reasons against.

I thought it was a list of things that had already occured and thus would not be sources of rising SST, but I think you listed them as sources of heat.

I believe it is my mistake.

Bob Tisdale said...

Carl: You wrote, "Let us assume that it was the following La Ninas that redistributed the heat poleward..."

The drop in the tropical Pacific OHC occurs during the El Nino, the discharge phase. And the increase in tropical Pacific OHC occurs during the La Nina, the recharge phase:
http://i25.tinypic.com/wrz71x.png

It's just the time lags (atmosphere and ocean) that makes the distribution of heat appear to take place during the La Nina.

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