How Significant Is This El Nino?

For months we have been told how this is a strong El Nino, similar to the “Super El Nino” of 1997-98. How does it really stack up?

As data for sea surface temperatures are not available before 1950, the Southern Oscillation Index (SOI) data from 1876 are the best for long term analysis. In this post I am using SOI data from the BOM archive.

The Bureau uses sustained (three month mean) SOI values of 7 or less as an indication of El Nino conditions. This plot shows three month mean SOI values from 1876:

Fig. 1: Three month mean SOI values from 1876

3m soi
It is plain that as of November 2015 the three month mean is still nowhere near as low as it has been in several past El Ninos (and 1997-98 was not the lowest either!)

The next graph compares the length of El Ninos.

Fig. 2:  El Nino length

EN length -7

Plainly 1941-42 was the one to beat, and El Nino conditions will need to persist for another 18 months to compare. Another four to six months is more likely, and of course there could be a double up of another El Nino next year (as happened in the 1990s).

I next calculate the relative strength of El Nino conditions, by summing the (inverted) SOI values of all months in El Nino i.e. that have a three month mean of -7 or less.

Fig. 3:  El Nino cumulative strength

EN strength -7

Unless we get another six months of values below -20 we won’t beat 1997-98 into fourth place.

Of course, we are only in the seventh month of this El Nino- how does it compare with this stage of previous El Ninos?

Fig. 4: Three month mean SOI value for seventh month of cycle

EN strength 7th mth -7

The November 2015 value is the black dot- in sixth place.

Compared with the strength of previous El Ninos, the seven month value of this one is also in sixth place:

Fig. 5:  Cumulative strength in seventh month of cycle

EN strength 7th mth integral -7

Another interesting method of comparison is to change the definition of “El Nino” to “El Nino or Neutral” i.e. periods between La Ninas.

Fig. 6:  Length of El Nino or Neutral conditions

EN length EN or neut

Note the two periods of nearly seven years without La Ninas in the 1980s and 1990s, separated by a 12 month La Nina- immediately followed by the 1997-98 event, and then another five year period. 2014-15 is not unusual.

The integral of SOI values, as a measure of the strength of El Nino:

Fig. 7:  Cumulative strength, El Nino or Neutral conditions

EN strength EN or neut

Currently this event is in 12th place, and if it runs strongly for another six months it could sneak into seventh place.

Compared with other events, at the 22nd  month this event ranks fourth.

Fig. 8:  Cumulative strength at 22nd month of cycle

EN strength 7th mth integral EN or neut


The current El Nino event is not going to break any records, unless it continues for several years!

It is nowhere near the most intense, nor the longest, nor the strongest.

It cannot compare with the intensity of previous El Ninos, as measured by three month average values, such as in 1896, 1905, or 1983.

It cannot compare with the length of previous El Ninos, such as the 1941-42 event, or the series of years of El Nino and neutral conditions in the 1980s and 1990s.

Depending on the measure used, it is fourth or sixth strongest for this stage of the cycle. If it continues strongly, its final strength might reach seventh or perhaps even fourth place. But that is unlikely. According to the Bureau, this event will peak before the end of 2015, and finish by mid-Autumn.

Fig. 9:  Model outlooks for El Nino end

Despite the hopes of the global warming enthusiasts, this is just another moderately strong El Nino which may cause a spike in world temperatures in the first half of next year, but is nothing to get excited about.



16 Responses to “How Significant Is This El Nino?”

  1. trevor prowse Says:

    thanks for this information—I don`t know how you get the time to do this research, which should be the job of the BOM

  2. MikeR Says:

    Hi Ken,

    If this is just “a run of the mill” El Nino then this makes the record smashing warmth of the past couple of months for GissTemp, Hadcrut and NOAA very surprising.

    Equally surprising are that October and November 2015 of the UAH V6.4 data, are records for their months .

    The UAH data typically peak some 6 months after the maximum Nino 3.4 value which is currently at 3.0 compared to the November 1997 maximum of 2.8 – see .

    We may then have to wait until sometime around early to mid next year for the spike in UAH to occur.

    Can you imagine what would happen if we got a major El Nino instead of this pathetic imitation?

    • MikeR Says:

      Just a quick update before the imminent release of the January 2016 UAH data which might keep us occupied.

      The December data for both satellites and all surface measurements all are in agreement once again that December 2015 was the hottest December on record. This makes 3 months in a row. Also the RATPAC radiosonde data is also agreement that these past 3 months have been the hottest on record for this time of the year.

      In fact if you average the data from August to December for all the satellite data and surface data sets they all agree that on average these 5 months are the hottest on record for this period.

      Finally we have agreement between the satellite and surface records. Hallelujah!

      • kenskingdom Says:

        Again you are fixated on weather- 3 months or 5 months being a record- big deal! This is of no importance at all and I will not comment further on this.

        • MikeR Says:

          In some sense it is weather due to the El-NIno but in another sense it is climate, as you are comparing the same set of months from 1979 until 2015.

          My comment was also trying to make the point that each data set now totally agrees on something. I thought that might have been a point to rejoice rather than disparage.

  3. kenskingdom Says:

    Imagining has no part to play in climate analysis. We shall see what happens when it happens. This El Nino is NOT an example of “stronger El Ninos followed by stronger La Ninas”.

  4. craigm350 Says:

    Reblogged this on CraigM350.

  5. tailingsproject Says:

    Thanks Ken for presenting all the SOI charts.

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  7. cementafriend Says:

    Hi ken, Interesting about the 1941-42 SOI. That was when Dr W Kreutz in Germany and a scientist in India (I think the name is Misra) separately measured CO2 levels in the atmosphere close to the present (380-400+ppm) see for a note about Kreutz.
    re SOI for recent times I do not trust BOM so I take my SOI from the Qld Long Paddock
    (Qld has a Public Sector Ethics Act which applies to all Qld Public Sector including Universities & Local government I do not think the long paddock people would fiddle with the figures)
    The explanation says “A Troup SOI of -10 means the SOI is 1 standard deviation on the negative side of the long-term mean for that month” Prolonged periods of -10 or lower (10-18 months – see graph for 1998, 1941 or 1905) are regarded as El Nino periods while prolonged periods of +10 or higher (10-14 months see 2011 or 1975) are regarded as La Nina periods.
    All the best for Christmas and New Year

    • kenskingdom Says:

      BOM has recently gone from -8 to -7 over 3 months (plus NINO 3.4 over 10, and another value I can’t recall) as El Nino indicator. I like the Long Paddock ‘phases’ as they are good indicators of changing conditions.
      The Commonwealth has a public service act as well and high expectations. The BOM has its own high sounding standards which they don’t meet. I wouldn’t put any more trust in a Qld entity- treat all with scepticism.

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