Sea Level Update: More Upward Revision Found

I have to say I was looking forward to the eventual release of the Global Sea level data from the University of Colorado because it was clear from the last update in August that 2010 was going to show a significant drop in sea level from 2009 and I was curious how it would be dealt with.  Now it is clear that the latest update included a substantial revision to the data, not just the recent data, but all the data.  I guess I should not be surprised by this as it has happened with numerous other data sets.  If the data doesn’t support your view, do a revision that fixes the problem.

Nor is this a trivial change.  It adds on average 2.6 mm to the global sea level, but not surprisingly it does so more as time goes forward.  That average of 2.6 mm is from 1993-2010.  The average difference in 2009-2010 is a stunning 4.7mm. After enough tweaking they managed to get 2010 to show a minor increase in sea level from 2009.  Here is the version difference between the data that was released last fall and the most recent version.

The Inconvenient Skeptic

Adjustment to the Seasonal Signal Retained, Inverse Barometer Applied data from the University of Colorado.

There is a trend in the adjustment of 0.25mm/yr.  So over the course of the past 18 years the cumulative addition to the new version is the most recent 4.5mm offset.  I suppose that is a valid peer-reviewed way to ensure that the data matches the theory.  This type of revision is really becoming all too common in data that is supposed to be public and paid for by tax dollars.

Here is the full scale comparison of the two versions of what is supposed to be the same data.

The Inconvenient Skeptic

(Red) New Version of sea level (Purple) Version that was valid until a few weeks ago.

The scale does make it hard to see how the versions are different today, so I will also show the versions since 2004.

The Inconvenient Skeptic

(Red) New Version of sea level (Purple) Version that was valid until a few weeks ago.

I still have lots of number crunching to do on this, but it is clear that they are not going to play science in a proper manner.  There is still a lot of looking through the update and the switch over to Jason-2 which appears to be the justification for switching over to the revised tick up in the global sea level.

I will also be looking at the acceleration for the new data as well which will clearly have a bias as the other data is simply not available for the update.  The timing of this with the IPCC energy report means that there is lots of information to sort through over the next couple of weeks.  Updates will be available as I get them completed.

Posted in Ocean: Sea Level and SST by inconvenientskeptic on May 9th, 2011 at 6:21 am.


This post has 10 comments

  1. Mike Jonas May 9th 2011

    They added 0.3mm p.a. to compensate for GIA. In other words, they have added a 0.3mm p.a. amount to sea level which did not actually happen.

  2. Mike Jonas May 9th 2011

    re the drop in sea level from 2009:
    I have done another couple of graphs, using the new data, which I think are illuminating: I did a least squares linear fit for two line segments, where the ‘flex point’ was itself optimised not pre-chosen:
    It clearly shows how the rate of sea level increase has slowed (from ~3.53mm p.a. to ~1.94mm p.a).[including the +0.3mm p.a. GIA]
    The second graph has the first trend line extended:
    It shows that the 2010 El Nino was insufficient to bring the sea level back to the original trend. To my mind, that indicates that the cause of the lower recent rate is not the La Ninas, as Colorado Uni suggest (they don’t claim it, only suggest it), but could be the PDO phase. The reasoning behind this is that El Ninos in the past appear to have caused at most temporary increases, not a change in trend. There is presumably no reason why La Ninas should behave differently.

    I have emailed the graphs and this suggestion to Colorado Uni for their comment.


  3. inconvenientskeptic May 9th 2011

    Yes. I have read they are trying to compensate for the expanding surface of the ocean for a total rise of 3-4 cm. Amusing justification.

    But it is also clear from the time fixed difference that they are not consistently applying anything. The effect is that they are adding more rise to the sea level with time. They are no longer just reporting the data.

  4. A G Foster May 9th 2011

    The first question is, should they measure sea level from the the shore or from the ocean bottom? That is, do we want to know how much water is in the ocean, or how fast it is creeping up the shoreline? I suppose an alarmist would be more interested in the latter, but a scientist in the former. And a scientist would have little trouble keeping track of definitions. Basin loading must be dealt with. It’s not imaginary, and the important thing is to know how much ice is melting, and how the mantel is responding. This has little to do with the threat of rising seas, which for the most part is imaginary.

    Now you might object, if we add the effect of basin subsidence why should we not subtract the effect of thermal expansion? That is, if we are not going to define sea level from the surface, why should we worry about volume rather than mass? Well we need to keep track of all three measurements, and the least important is shore measurement, even if you live in Amsterdam or Dacca.

    But surely you should take into account any subsidence of the measuring station. If millions of tube wells are dropping your gauge ten times faster than the sea is rising, that’s something you might want to know. And once you take subsidence into account it is no longer “raw” data. It is simply “useful” data, depending on your purposes. Then I ask, why will you adjust data for shoreline subsidence and not for basin subsidence, if your purpose is to determine ocean volume?

    We don’t want to confuse molarity with molality, and most sophomore chemists don’t. Nor do we wish to confuse various levels of adjustment of sea level measurement, and there is no excuse for doing so. But the fact that sea basins fill faster than they appear because of subsidence is something that must be taken into account at some point, and there is no reason to condemn it as sleight of hand. Such skepticism is a little too convenient. –AGF

  5. Alas, just “reporting the data” doesn’t get you much in the research funding game…

  6. inconvenientskeptic May 9th 2011


    The measurement is satellite. The land plays little role in the measurements used for this. I will put some estimates of how foolish this idea of spread is in the next sea article.

  7. Bruce May 9th 2011

    What a lesson.

    1) Notice big drop in the poster boy for vlimate change

    2) Stop publishing data

    3) Adjust data

    4) Come up with bogus excuse for adjusting data

    5) Publish new bogus data

    6) Claim that the data shows that AGW is “worse than we thought”.

    7) Question why no one trusts ANYTHING that a climate scientist says or writes…blames it on bad messaging.

  8. Richard111 May 10th 2011

    For sea level rise are we assuming an increase in the VOLUME of the sea water? If so, there must be a corresponding increase in mass, therefore the sea bottom could sink? What are the satelites measuring?
    There must be mass transfer from the poles to the equator if sea level is rising due to increasing volume. Would this not influence the rate of rotation of the planet? Has this been observed?

  9. inconvenientskeptic May 10th 2011


    Most of the change in level is associated with change in temperature. The seasonal changes that happen are associated with the summer and winter in the SH. When the ocean warms up there, the sea level rises. In the SH winter the reverse happens.

    Variation in temperature is the primary source of the recent change in sea level.

    See this.

  10. David A May 11th 2011

    Dear John

    Thank you for all your hard work on this. It should not be, but is surprising how this is done. I think it is a huge issue and I hope the skeptic community gets together to thouroughly audit this. Is Steve McIntyre involved?

    I remember the old orginal UC SL chart which WAS on Anthony Watts sea page. That chart showed things almost flat since the end of 2005. I liked seeing the seasonal changes as well. I would like to see what that chart would look like without the changes, but updated WITHOUT the new methods, and left with the seasonal changes. I cannot even find a screen shot of the old chart.

    BTW one minor quibble about a comment you left at WUWT.
    John Kehr says:
    May 10, 2011 at 4:45 am
    “Since TSI is how the warmists try to discredit Milankovitch I remain skeptical. While total TSI might matter somewhat, it matters more where that energy is striking the Earth. That is why the Earth is colder in January when the Earth is closest to the sun and warmist in July when it is farthest from the sun.”

    I like this subject because the seasonal TSI change is about 6%. However the fact is that ONLY the atmosphere is cooler January, when in fact the earth is probably warming, (via the southern ocean absorbtion of TSI in to it, and this energy intake may exceed the earths increased albedo due to greater snow cover in the norethern winter.

Web Design & Dev by

Mazal Simantov Digital Creativity