Skip to content

New Paper On Sea Level Rise Adjusts The Data To Match The Models

January 18, 2015

By Paul Homewood




I meant to have a look at this paper last week, but with the kerfuffle over GISS, it had to go on the back burner.

This is the Abstract:


Estimating and accounting for twentieth-century global mean sea-level (GMSL) rise is critical to characterizing current and future human-induced sea-level change. Several previous analyses of tide gauge records1, 2, 3, 4, 5, 6—employing different methods to accommodate the spatial sparsity and temporal incompleteness of the data and to constrain the geometry of long-term sea-level change—have concluded that GMSL rose over the twentieth century at a mean rate of 1.6 to 1.9 millimetres per year. Efforts to account for this rate by summing estimates of individual contributions from glacier and ice-sheet mass loss, ocean thermal expansion, and changes in land water storage fall significantly short in the period before 19907. The failure to close the budget of GMSL during this period has led to suggestions that several contributions may have been systematically underestimated8. However, the extent to which the limitations of tide gauge analyses have affected estimates of the GMSL rate of change is unclear. Here we revisit estimates of twentieth-century GMSL rise using probabilistic techniques9, 10 and find a rate of GMSL rise from 1901 to 1990 of 1.2 ± 0.2 millimetres per year (90% confidence interval). Based on individual contributions tabulated in the Fifth Assessment Report7 of the Intergovernmental Panel on Climate Change, this estimate closes the twentieth-century sea-level budget. Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records4. The increase in rate relative to the 1901–90 trend is accordingly larger than previously thought; this revision may affect some projections11 of future sea-level rise.



In short, they are claiming that the rise in sea levels during the 20thC was much less than originally thought. This would mean that sea level rise since 1993 had accelerated more than believed.

They arrive at this conclusion because their models suggest that glacial melting, thermal expansion etc cannot account for all of the rise of 1.6 to 1.9mm pa. They then use more models to recalculate a figure of 1.2mm between 1901 and 1990, which they say neatly fits their first model.


In doing so, they negate many earlier expert studies, such as Church & White, who found in 2006 that:


Here, we extend the reconstruction of global mean sea level back to 1870 and find a sea-level rise from January 1870 to December 2004 of 195 mm, a 20th century rate of sea-level rise of 1.7 ± 0.3 mm yr−1 and a significant acceleration of sea-level rise of 0.013 ± 0.006 mm yr−2.


Or Bruce Douglas:


The value for mean sea level rise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880–1980 is 1.8 mm/yr±0.1.


These scientists, and many others who have come to similar conclusions, are all highly expert and experienced in this field, so it would seem to be astonishing that their work could be overturned so easily.

With this background, it would have seemed logical for the authors of this new study to question why their models did not fit the data. After all, the data would suggest that maybe glacial melt was greater than they thought in the early 20thC, or that global temperatures were actually higher than the constantly revised and adjusted numbers they had been given to work with.

But no, they ploughed ahead to make the data fit the models.


Now, of course, they might just be right. But, on the other hand, another paper published only a month earlier, (and, to the best of my knowledge, not publicised as this one has been), suggests that they are totally wrong.







The global mean sea level (GMSL) changes derived from modelling do not match actual measurements of sea level and should not be trusted. Compilations of individual tide gauges of sufficient quality and length provide much more reliable information. The present work is a contribution towards a better understanding of the observed of sea levels in India and its relation to worldwide observations. The latest average relative rate of rise of worldwide sea levels from a compilation of 170 stations with more than 60 years of data returns an average relative rate of rise +0.25 mm/year. The individual rates of rise are about constant in between subsequent updates suggesting the absence of any acceleration. Observation in key sites suggests a similarly stable pattern. Along the coastline of India, the average rate of rise of sea level is +1.06 mm/year computed by considering the 11 longest tide gauges of average length 51 years. Shorter records may overrate the sea level rate of rise because of the local phasing of the quasi-60-year oscillation. In the longest records, the rates of rise are decreasing since 1955. The lack of any GPS monitoring of the vertical position of the tide gauge does not permit the determination of the absolute rates of rise.



Of course, academics will always disagree, but these findings are pretty damning for the made up numbers from the Carling Hay paper.

It is hard to see how it ever found its way through peer review.  

  1. Retired Dave permalink
    January 18, 2015 7:26 pm

    I still maintain that when it becomes obvious to all that the potentate is indeed totally garment-less some folks are going to have mental health issues, just as some Christians did in the mid-late 19th century when it became obvious that the world was not 6000 years old. Oh! of course some still think that it is.

    • A C Osborn permalink
      January 18, 2015 7:48 pm

      Some think the world started around 1900, they appear to know nothing of Earth’s history.

  2. January 18, 2015 7:29 pm

    With all the splitting of hairs on sea-level rise, I am left wondering what makes current sea-level rise much different from rates in the last 150 years. I mean, when will Miami, Florida be uninhabitable?

    • manicbeancounter permalink
      January 18, 2015 8:57 pm

      It depends. Assume that nothing is done about flood defenses, and the critical level is just 6 feet.
      If you extrapolate from tide gauges, then that could be 1000 years.
      If you extrapolate from satellite readings, then it could be in 500-600 years.
      If you extrapolate from the top-end estimate of the IPCC report then it could be 150-200 years.
      If you listen to Professor Harold Wanless (A senior geology professor in Miami, who also chairs the science committee for the Miami-Dade Climate Change Advisory Task Force) then it could be before the end of this century.

      • January 20, 2015 3:44 am

        Thanks Manic! I appreciate the link and your calcs…I’ll keep checking on Miami.

  3. HenryP permalink
    January 18, 2015 7:35 pm

    ….In the longest records, the rates of rise are decreasing since 1955……

    which is what one would expect, given the natural climate change we are experiencing.

    A question to ponder further to the above would be to know exactly how accurate were the measurements 88 years ago?

  4. manicbeancounter permalink
    January 18, 2015 7:42 pm

    I am a bit confused by reference 4 as in this comment.

    “Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records (4).”

    Click on the reference and you get

    4. Church, J. A. & White, N. J. Sea level rise from the late 19th to the early 21st century. Surv. Geophys. 32, 585–602 (2011)

    Church & White begin the abstract with:-

    “We estimate the rise in global average sea level from satellite altimeter data for 1993–2009….”

    Can you spot the reason for my confusion?

    • A C Osborn permalink
      January 18, 2015 7:50 pm

      Yes, the real, actual Tide Gauge measurements do not count and have to be adjusted.
      You may not believe this but the BEST “Final” data set is also based on exactly the same ideology.

    • January 18, 2015 9:44 pm

      We estimate the rise in global average sea level from satellite altimeter data for 1993–2009 and from coastal and island sea-level measurements from 1880 to 2009. For 1993–2009 and after correcting for glacial isostatic adjustment, the estimated rate of rise is 3.2 ± 0.4 mm year−1 from the satellite data and 2.8 ± 0.8 mm year−1 from the in situ data. The global average sea-level rise from 1880 to 2009 is about 210 mm. The linear trend from 1900 to 2009 is 1.7 ± 0.2 mm year−1 and since 1961 is 1.9 ± 0.4 mm year−1. There is considerable variability in the rate of rise during the twentieth century but there has been a statistically significant acceleration since 1880 and 1900 of 0.009 ± 0.003 mm year−2 and 0.009 ± 0.004 mm year−2, respectively. Since the start of the altimeter record in 1993, global average sea level rose at a rate near the upper end of the sea level projections of the Intergovernmental Panel on Climate Change’s Third and Fourth Assessment Reports. However, the reconstruction indicates there was little net change in sea level from 1990 to 1993, most likely as a result of the volcanic eruption of Mount Pinatubo in 1991.

    • January 18, 2015 11:11 pm

      I think they mean that they get the same 3mm/yr rise since the 1990’s as Church & White found

  5. January 18, 2015 9:37 pm

    Thanks, Paul. An excellent article.
    It seems like sea level rise is very difficult to measure.
    According to the Sea Level Research Group, University of Colorado, the mean rate of global sea level rise is 3.2±0.4 mm/yr.
    This Includes a “global mean glacial isostatic adjustment (GIA)” correction of 0.3 mm/yr. The GIA uncertainty is at least 50 percent (I prefer to remove it, so it is 2,9±0.4 mm/yr).
    (Measurements from the TOPEX and Jason series of satellite radar altimeters)
    See (2014-11-04, has not been updated since).

  6. January 19, 2015 2:12 am

    Reblogged this on

  7. January 19, 2015 4:50 am

    Tide records are very dodgy because they not only record the increase in sea level but also the falling of the land along the seashore.

    Land sinks in some places because of extraction of groundwater (Jakarta in Indonesia).

    In other places geological plates move up and down.

    In still other places the weight of sediment brought down by major rivers such as those in Bangladesh and the Nile in Egypt depresses the river deltas, ..

    Yet in other places the land along the seashore is falling because the Earth’s crust is still adjusting to the melting of the glaciers.

    The last of these results from the decline of the “forebulge” an isostatic phenomenon well known to geologists that affects the east coast of the USA. The phenomenon was described by the experts who advised the state commission responsible for the study, but omitted from the report of the commission, presumably because it was an inconvenient truth.

    • TomK permalink
      January 19, 2015 2:28 pm

      So…..Is there not some effect on sea level that is attributable to water that is being displaced by sediment that is settleing to the bottom of the oceans? I would think the sediment amounts river by river would be somewhat sporadic but here again the global average sediment load carried by all rivers in aggregate would likely be more uniform.

  8. January 19, 2015 7:12 am

    Pinatubo eruption in 1991 depressed sea levels around world for a few years (ie SLR was negative). After a bit sea levels bounced back, then in 1997/8 there was an exceptionally large El Nino which raised sea levels around the world.

    The net effect of Pinatubo and 97/8 El Nino was for a short term rate of sea level rise was higher than normal, even measured by tide gauges.

    Was this due to CO2 – no
    Was this the start of long term trend – no

    Post 2002 even satellites show a rate SLR than 3mm/year. Perhaps they forgot to adjust it.

    In any case what are the errors on satellite measurements? Steve Goddards shows graphs which indicate the error is a similar size to the measurements – in other words there is little or no sea level rise.

    I have fitted a linear trend to all sites which PSMSL has records for. 1/3 of sites have a negative rate of sea level rise (though as been pointed out this includes land movement).

  9. January 19, 2015 9:57 am

    Paul, as on last year”s ‘wettest winter ever’, your recent calm, informative coverage of the great ‘2014 hottest year ever’ hysteria has, with a little help from those Woodfromthetrees graphs, been unsurpassed and much appreciated!.

    • Bloke down the pub permalink
      January 19, 2015 3:40 pm

      Always a pleasure to see you here Mr Booker. Just wondered if the double h in your name is a local dialect?

  10. Bloke down the pub permalink
    January 19, 2015 3:38 pm

    From the Indian paper- ‘The lack of any GPS monitoring of the vertical position of the tide gauge does not permit the determination of the absolute rates of rise.’

    Considering the scope for error in measuring SL from satellites, and the problems with subsidence and uplift of tidal gauges, isn’t the best way to overcome these deficiencies by regular gps surveying of all tidal gauges? If this is being done by someone, then there should be little room for doubt over where any discrepancies lay.

  11. January 19, 2015 6:58 pm

    I have Booker’s book, something about the global warming nonsense, with graphs, etc, which set me out to do my own investigations……

  12. Retired Dave permalink
    January 19, 2015 10:44 pm

    Modellers have always doubted real world data – the stuff is just a bloody inconvenience to them.

    You know the saying if it looks like a duck, walks like a duck, squawks like………. Well I can think of times when only the modeller thought it vaguely resembled a bird – and that was at day 6. 75 years should be a breeze (pun intended).

  13. January 20, 2015 2:53 am

    Reblogged this on Agenda 21: Your Freedom Under Attack and commented:
    With increased seal level rise claims the greens can claim even more shoreline from legitimate owners. It is Agenda 21 for sure.

  14. December 22, 2015 9:40 am

    We are apparently going to lose the rail links to the south west in the next 20 years due to sea level rises a new report has forecast.

Comments are closed.

<span>%d</span> bloggers like this: