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ENSO Trends

August 31, 2013
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By Paul Homewood

 

In the news this week has been a paper by Yu Kosaka and Shang-Ping Xie, “ Recent global-warming hiatus tied to equatorial Pacific surface cooling”.

The paper has been well covered by WUWT, and essentially claims that the recent halt in global warming has been due to natural factors. As the abstract quotes:-

 

Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase.

 

Most are aware, but just to recap, global temperatures tend to rise during El Nino periods, and drop with La Nina conditions. Although these events can alternate from year to year, over the longer term there are periods when one or the other dominate, as can be seen in the NOAA graph below. (ENSO stands for El Nino/Southern Oscillation – Reds are El Ninos)

 

ts

http://www.esrl.noaa.gov/psd/enso/mei/

 

These cycles last about 30 years, and are connected to the Pacific Decadal Oscillation, although the science is not well understood, (see here). The period from around 1975 to 2005, however, shows as one dominated by El Nino events, just as the one from 1950-75 was by La Ninas.

Kosaka & Xie, in their paper, are referring to the fact that we have recently returned to predominantly La Nina conditions. To put this all into perspective, I thought I would plot the actual trends, using the data from NOAA.

 

 

image

http://www.esrl.noaa.gov/psd/enso/mei/table.html

 

The Kosaka paper specifically talks about “decadal trends”, so we need to look at the 10-year running average.

It is clear from this that the positive, El Nino phase has ended. But it is also clear that , if the trend follows the 1950-75 period, the 10-year average will drop much further. At the moment, the 10-year average is in neutral territory, a cross over zone.

If the authors are correct, the “global warming hiatus” may well last another two decades, and may see not just a standstill but a fall in temperatures.

 

Remember as well that the Atlantic Multidecadal Oscillation, or AMO, is also in the middle of its warm phase, and as a result increases global temperatures – see here. When both the AMO and PDO are in cold phase together, if the authors are correct, there will be global cooling.

 

tsgcos.corr.innLL0fpST

http://www.esrl.noaa.gov/psd/cgi-bin/gcos_wgsp/tsanalysis.pl?tstype1=91&tstype2=0&year1=1900&year2=2012&itypea=0&axistype=0&anom=0&plotstyle=0&climo1=&climo2=&y1=&y2=&y21=&y22=&length=&lag=&iall=0&iseas=0&mon1=0&mon2=11&Submit=Calculate+Results

4 Comments
  1. August 31, 2013 3:04 pm

    Reblogged this on CraigM350.

  2. R2Dtoo permalink
    August 31, 2013 5:25 pm

    Simple and to the point. Let the data do the talking. Thanks Paul

  3. Dan Pangburn permalink
    September 1, 2013 1:43 am

    Average global temperature history since 1975 is like a hill. We went up the hill from 1975 to 2001 where the average global temperature trend reached a plateau (per the average of the five government agencies that publicly report average global temperature anomalies). The average global temperature trend since 2001 has been flat to slightly declining but is on the plateau at the top of the hill. Claiming that the hill is highest at its top is not very profound. The temperature trend has started to decline but the decline will be slow; about 0.1 K per decade for the planet, approximately twice that fast for land areas.

    GW ended before 2001. http://endofgw.blogspot.com/

    AGW never was. http://climatechange90.blogspot.com/2013/05/natural-climate-change-has-been.html

  4. Brian H permalink
    September 1, 2013 2:02 am

    It’s perverse that to defuse dangerous climate meme manipulation at the global politics level, we are reduced to hoping for cyclical global cooling to show its muscle, which will result in great suffering and expense.

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