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GISS & The Tampered ERSST Dataset

January 19, 2016

By Paul Homewood 




We are all doubtlessly familiar with Thomas Karl’s infamous “pausebuster” paper from last June. It achieved its aim of getting rid of the inconvenient pause largely by massive tampering with sea surface temperatures in NOAA’s Extended Reconstructed Sea Surface Temperature (ERSST) dataset.

The effect of their adjustments is shown on the GISS graph, published last July:




Note the veritable hockey stick starting in 1998. WUWT has already gone into great detail to discredit the whole exercise, so I don’t want to revisit that.

But there is an interesting background to ERSST which may shed light on motivations.

ERSST is not the only SST dataset, there are also Reynold’s OISST and the Met Office’s HADISST. In January 2013, GISS made this seemingly innocuous statement:




I made a bit of a fuss at the time, because the change added about 0.03C to the latest global temperatures, a small change, but, as we know, just one of series of small changes all in the same direction.

When I emailed Reto Ruedy of GISS (who I must say is always helpful), he replied:


Last week Dr. Hansen decided to switch to ERSST for the ocean temperatures rather than using our Hadley/Reynolds combination. We will write a note concerning that change with an analysis of its effect.

However, since the margin of error for these estimates even for the most recent years is about +-0.05 C, differences of the order 0.03 C are well within that margin of error, hence not significant.

I personally like the switch, since now all our basic data (land and ocean) come from the same source which simplifies the description of what we are doing.

Thank you for your interest,

Reto Ruedy


It all sounded very innocent at the time, although maention of “Dr Hansen deciding to switch” should perhaps have raised alarm bells. It is now becoming clear that plans were already afoot to get rid of that pesky pause. NOAA, of course, were already using ERSST. How much more convenient it would be for GISS to switch to the same dataset.

  1. January 19, 2016 1:27 pm

    Hansen is not a benign spectator. He has shown himself to be a principal “science liar”.

  2. January 19, 2016 2:00 pm

    Thanks, Paul. GISS is becoming more irrelevant.
    Note the incredible effect of the current El Niño in the 2015 spike.
    Note also how their global graphical products lack gridlines.

  3. David Richardson permalink
    January 19, 2016 3:06 pm

    Well just another massaging of a dataset. The amounts are always small, but frequent and always in the same direction – cooling past and warming the recent. The analysis at the WUWT link shows what has been done.

    Every new version has been altered in the same way, while assuring us that it is “new and improved”.

    If you don’t like what the data tells you change it.

  4. January 19, 2016 5:37 pm

    Reblogged this on Climate Collections.

  5. Dorian permalink
    January 19, 2016 7:31 pm

    In short, all this is saying, is that it is better to have convenient data than honest data.
    Reto Ruedy, where does it say that data collection convenience is more important in science, than accurate data? Simplification SHOULD NOT even enter your lexicon, Ruedy, if you are a serious scientist! Science is not about simplification, it is about understanding Nature whether it is simple or not!

    Once again Science suffers at the hands of a good-for-nothing!

    What next, science by lounge chair?

    Unbelievable! Ruedy you should be fired for incompetence, or at every least, laziness!

  6. Joe Public permalink
    January 19, 2016 7:42 pm

    “However, since the margin of error for these estimates even for the most recent years is about +-0.05 C, differences of the order 0.03 C are well within that margin of error, hence not significant.”

    I call bullshit.

    +-0.05K around +0.03K, leads to the range effectively being revised to -0.02K to +0.08K.

  7. nightspore permalink
    January 19, 2016 8:20 pm

    Given all the controversy surrounding AGW and the enormous implications for energy (and other) policies, I find the blandness of Ruedy’s remarks possibly significant in itself. Is this an example of blandness as brazenness? I don’t know, but at this point in the game I think it’s a distinct possibility.

  8. xmetman permalink
    January 20, 2016 4:30 pm


    Sorry I’ve had to post a comment to contact you again but it is on a very similar subject to this GISS article and I think you may find it of interest.

    It’s took me quite a bit of effort to gather the evidence which I believe to be correct, although I’m still waiting a reply from the Met Office to confirm what I’ve found, I think a week is enough time to come up with a reply to what were very simple questions.


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