RealClimate logo

Note 3/23/2021: we had a few hiccups with comments after moving the site to https/SSL. Hopefully they're fixed now. Please let us know if there are remaining issues.

Is Sea-Level Rise Accelerating?

Filed under: — stefan @ 12 July 2011

A few months ago a paper by Jim Houston and Bob Dean in the Journal of Coastal Research (JCR) cast doubt on whether global sea level rise has accelerated over the past century or so. As things go these days, ‘climate sceptics’ websites immediately heralded this as a “bombshell”. A rebuttal by myself and Martin Vermeer has now been published in JCR.

The keystone of the argument by Houston & Dean is the fact that a prominent global sea level reconstruction (Church & White 2006) shows no acceleration since 1930. Which raises the question: why 1930, given the sea level data set starts in 1870? The reason becomes immediately evident when looking at the acceleration starting from any arbitrary date (Fig. 1).

Figure 1. Acceleration of sea-level rise (i.e., twice the quadratic coefficient) from different starting years up to 2001 in the global tide gauge data set of Church and White (2006; red line with uncertainty band). Note that after ~1960 the calculation gets excessively ‘noisy’ because the time interval gets too short to robustly compute acceleration. I graphed this right away after reading the Houston & Dean paper, and a few days later Tamino independently came up with a similar plot – it’s the obvious thing to do. The blue line shows the same quantity from the sea-level hindcast of Vermeer & Rahmstorf (2009) computed from global temperature data.

Around 1930 we see a unique minimum in the acceleration curve – I will explain the cause of this shortly. Other start dates either before or after this minimum show positive acceleration. Picking 1930 for this analysis is thus a classic cherry-pick, and according to the authors that is no accident. They write in the paper: ‘Since the worldwide data of Church and White (2006)…appear to have a linear rise since around 1930, we analyzed the period 1930 to 2010.’ The interval was thus hand-picked to show a linear rise rather than acceleration.

Connection to temperature

Houston & Dean use their result to question the future acceleration of sea level rise predicted by Vermeer & Rahmstorf (2009) for the 21st Century as a consequence of global warming. They argue that the 1930s acceleration minimum calls into question the semi-empirical link between global temperature and global sea level proposed by us in that paper. However, it is clear they never bothered to check this, because quite the opposite is the case: our semi-empirical formula predicts this acceleration minimum, as the graph above shows. As it turns out, this is an expected outcome of the mid-20th-Century plateau in global temperature.

If one subtracts out the non-climatic sea level change due to water stored in artificial reservoirs on land, as we did in Vermeer & Rahmstorf (2009), then the agreement between the acceleration curve predicted from global temperature with the actually observed curve is even better (graph below). Thus, the 1930s acceleration minimum pointed out by Houston & Dean supports our approach and projections rather than challenging them.

Figure 2. The same as Figure 1, but here the sea-level data are corrected for water storage in artificial reservoirs (Chao, Wu, and Li, 2008).

Regarding our projections of future sea level rise, Houston & Dean write:

it is not clear that the acceleration necessary to achieve these comparatively large projected rises in mean sea level over the course of the 21st century is evident in tide-gauge records.

That is a puzzling statement. Why would the acceleration we expect only for the 21st Century already show up in tide gauge records of the 20th? Since we expect a temperature rise to cause an acceleration of sea level rise, the acceleration in the 20th Century (which has seen only 0.7 ºC of global warming) must obviously be much smaller than that expected for the 21st Century, for scenarios of a many times greater warming.

Further issues raised by Houston & Dean

Houston and Dean raise a number of further points (beyond the Church & White global data set) on which we just cite the brief summary statements and refer the readers to our journal comment for more detail:

  • Many U.S. tide gauges show a deceleration; since 1930, most of them do.

However, again, 1930 is a special choice, and U.S. tide gauges only provide a regional signal, not a global one.

  • The authors’ extension of the Douglas (1992) sea-level compilation shows a sea-level deceleration for 1905–2010.

But this data set is not a properly area-weighted global average but is instead highly biased to the Northern Hemisphere. It is known that the twentieth-century acceleration is largely found in the Southern Hemisphere (Merrifield, Merrifield, and Mitchum, 2009), and the only two Southern Hemisphere groups in the extended Douglas data set indeed show acceleration.

  • Decadal trends in tide gauge compilations show large variations over the full record, and the most recent decadal trends are not unusual.

However, these variations in decadal tide gauge trends are not a climate signal but rather are dominated by sampling noise due to the inadequate number of tide gauges.

  • The satellite altimeter record shows a slight deceleration since 1993.

But this time interval is far too short to draw any conclusions.

In our comment we conclude:

None of this supports a lack of acceleration in global sea-level rise, as compared to what is expected from global warming. Outside a few starting years around 1930, global sea-level reconstructions robustly show a modern acceleration of sea-level rise in conjunction with global warming.

For the evidence, just have a look at some of the references listed below.

p.s. I just see that JCR also carries a reply by Houston & Dean to our comment. This largely focuses on our supposedly “selective” use of data, because we show the acceleration of sea level rise ‘only’ for starting years from 1870 (the start of the data set) to 1970 (after which the computation is too noisy to be meaningful by anyone’s standard). This is slightly ironic given that Houston & Dean focused only on the rather unique start year 1930. Houston and Dean further argue that the data already become too noisy around 1940 because “decadal fluctuations begin to dominate records shorter than about 60 years, and accelerations become increasingly meaningless for starting years in Figure 1 greater than about 1940”. We disagree: while this may be true for individual records it is not true for the global sea level reconstruction shown. The 2-sigma range and the fact that the curve is smooth until then shows it is meaningful up to about 1960; we continued the graph up to 1970 in order to show (rather than just claim in the text) how the uncertainty explodes after 1960. In any case, by showing the plot until 1970, we allow readers to see the full potentially meaningful range and judge for themselves whether they see any significant difference between the data and our model. That our model is somehow called into question by the observed sea level acceleration was, after all, a key claim in Houston & Dean’s original paper.

Houston & Dean excuse the strong northern-hemisphere bias introduced by their simple averaging by saying that “this criticism would apply to any study of sea-level rise”. That is not true; the sea level data set we use (Church and White 2006) and also the temperatures (GISS) use an area-weighted averaging scheme that makes sure the northern and southern hemispheres are properly represented in proportion to their surface areas, regardless of the data density.

But at least on one thing we agree. As Houston & Dean state in their final sentence, we indeed predict a much larger acceleration of sea level rise in the 21st Century than is observed in the 20th Century. That is a direct logical consequence of the fact that we expect much larger warming in the 21st than in the 20th.

Update 24 July: A related case of “lack of acceleration” – also from the Journal of Coastal Research – is expertly treated by Tamino here: How Not to Analyze Tide Gauge Data. It does raise some questions about the quality of peer review at JCR.


PIK sea level pages


Church, J. A., N. J. White, 2006: A 20th century acceleration in global sea-level rise. Geophysical Research Letters, 33, L01602.

Douglas, B. C., 1992: Global sea level acceleration. journal of Geophysical Research-Oceans, 97, 12699-12706.

Houston, J., R. Dean, 2011: Sea-level acceleration based on US tide gauges and extensions of previous global-gauge analysis. Journal of Coastal Research.

Merrifield, M. A., S. T. Merrifield, and G. T. Mitchum, 2009: An Anomalous Recent Acceleration of Global Sea Level Rise. Journal of Climate, 22, 5772-5781.

Rahmstorf, S. and M. Vermeer, 2011: Discussion of: Houston, J.R. and Dean, R.G., 2011. Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses. Journal of Coastal Research 27, 784–787.

Vermeer, M., S. Rahmstorf, 2009: Global Sea Level Linked to Global Temperature. Proceedings of the National Academy of Science of the USA, 106, 21527-21532.

192 Responses to “Is Sea-Level Rise Accelerating?”

  1. 51
    Tilo Reber says:

    Sekerob: “Help nearby, there is the inimitable Google and low…”

    Yes, unfortunately Barton was wrong. I used monthly data that came up to date, Barton used yearly data that didn’t. For some inexplicable reason Barton seemed to think that trending yearly data was more accurate than trending monthly data.

    Barton claimed that my flat trend was based on ENSO cherry picked end points; I showed Barton that you could use ENSO corrected data and still get the same flat trend. Of course there was no chance that Barton was going to let me give my side on his web page.

    I’m assuming that since Gavin let you attack me on a subject that had nothing to do with the thread, that he will let me defend against that attack.

  2. 52
    schmert says:

    Response: This is called the “Inverse Barometer” affect and can be corrected for ( has graphs with and without this correction). Basically, if you have a atmospheric low pressure system compared to a high pressure system, sea level is just a little higher (for a 10mb difference in atmos. pressure, you get a 10cm rise in local sea level). It doesn’t make much difference to the long term global trends but it does reduce the variance a little. – gavin

    You do need to know that when you’re trying get the Nimitz into a port with a Sand Bar ?!

    From what I can tell and from my personal conversation Professor Corrine the biggest problem with accurate readings is the actual effects of the escalators : I saw a schematic about 10 years ago and they’re swinging widely, but they’re not shutting down, the tips seem to feed of ice, oscillating, feeding the convection current, preferring cold to warm rather vice versa ? : i strongly suspect theirs a few other issues involved.

    the key driving mechanisms of the chaos of the planet’s weather systems, and that’s the question of whose budget ?

    and it’s not being factored into the equation : and that’s an ask nicely we might be able to get a military satellite re-directed.


  3. 53
    Martin C says:

    #39 Didactylos says . . .

    If more than 40 years of data is required to get a better ‘trend’ , then see the following link – it contains a chart showing global cumulative sea level change for 1900 to 2002

    []. The slide I am referring to is the 14th slide in the presentation. And this presentation is concerned about sea level rise from C02 warming . . .

    Not much of an acceleration on the plot, and you mention with this article, the acceleration is small and hard to see.

    Yet even IF sea level rise were accelerating by 0.2 mm/yr), starting with a 3.2 mm/yr increase (per the University of Co. website), the increase in sea level over 20 years would only be about 4 1/4 inches. Easy to adapt to. But let’s watch the data over the next 5-10 years to see how the trend is changing first.

    [Response: Am afraid you’re still not getting the time scale involved. In our Vermeer and Rahmstorf 2009 paper we use ~15-year averaging for the data. The entire satellite record is one data point (which very nicely fits our model, although this point is not used in calibration). To get the next data point which might give some reasonably independent info we now have to wait another 15 years. Anything shorter is noise – judging from the past data – and not in any way correlated with the temperature evolution. -stefan]

  4. 54
    Benjamin says:

    Quote : [Response: Is it conceivable that linear extrapolation is not the optimum way to assess risk? – gavin]

    Well, that’s what is implied in the reply paper as they use x=At^2+Bt+C …

  5. 55
    simon abingdon says:

    So, not only is the rate of sea-level rise accelerating (a horizontal blue or red line would show that), but the rate of acceleration is itself increasing, and until recently not just linearly (a line of constant slope would show that), so the rate of acceleration has itself been accelerating. Phenomenal.

  6. 56
    simon abingdon says:

    Correction, the rate of acceleration increase has itself been accelerating.

  7. 57
    simon abingdon says:

    And since the rate of acceleration increase = the acceleration of the acceleration, we can say that (between about 1940 and 1960) the acceleration of the acceleration was accelerating.

  8. 58
    t_p_hamilton says:

    Simon, the acceleration is not necessarily changing. The x axis is NOT time, so you can’t take the slope as being the third derivative. Ironically the captcha is years.

  9. 59
    Sekerob says:

    # 51 Tilo Reber says: 13 Jul 2011 at 12:17 PM

    If so, I owe both you and BPL an apology for dragging out an old expired document, last revised Feb.2011. Could not see anything wrong with it after perusing, before posting.


  10. 60
    simon abingdon says:

    tph The x-axis does look rather like time and the blue line being shown as a smooth curve, your point must be one of some subtlety.

  11. 61
    NikFromNYC says:

    The latest Church & White update includes a plot of a simple average of tide gauges, plotted in hard-to-see yellow on top of darker plots that obscure it’s linear nature, one that shows no trend change going back 150 years:

    What is labeled “mean sea level” in their final up-swinging graph is not really actual sea level but one “corrected” for the estimated effect land based water reservoirs, this correction is not referenced except as a “private communication.”

  12. 62


    Please don’t apologize, Sekerob. A cherry-pick remains a cherry-pick, whether measured in months or in years.

  13. 63
    Paul S says:

    #61, NikFromNYC – You’re a bit confused there. The reservoir correction is based on Chao et al. 2008, which is referenced as… Chao et al. 2008.

    The personal communication reference is for the impact of ground water depletion which offsets some of the reservoir correction.

  14. 64
    NikFromNYC says:

    #63 Paul S referenced Chao’s claim that reservoirs have subtracted 3 cm from the sea level. I point out that this means that minus AGW-caused enhanced sea level rise, a seemingly unexplained natural dive in sea level of 3 cm has been nearly exactly avoided, due to the trend in tide gauges being so linear (larger image of the Church & White 2011 plot here: That seems a bit odd, given that T has been rising in that same 150 years. Minus a mechanism for this avoided dip, the argument that actual sea level should be replaced by a virtual one is much less convincing.

  15. 65
    EFS_Junior says:

    The rebuttal of the rebuttal of the rebuttal.

    Are HD the zen masters of the cherry pick? Absolutely!

    From there 2nd paragraph in their reply to RV, HR state;

    “In Figure 1, RV show only the data that agree with their
    model. On the x axis of Figure 1, record lengths are shorter
    than 60 years for starting years after around 1940. It happens
    that at around 1940 the acceleration shown is approximately
    zero. Thus, as seen in Figure 2, the record from 1940 to 2001
    has a strong linear trend with decadal fluctuations but
    approximately no acceleration. If the record from 1940 to
    2001 has zero acceleration, how is it then possible that all
    shorter records (starting years after 1940) shown in Figure 1
    have positive accelerations that increase as record lengths
    shorten? It is not possible. Again, RV only plot the data as long
    as they agree with their model. If the plot is extended, e.g., to
    the starting year of 1985, the acceleration is 20.044 mm/y2,
    more than twice the range shown for negative accelerations in
    Figure 1. If the plot is extended further, the folly of analyzing
    records shorter than approximately 60 years becomes increasingly
    obvious. The acceleration for a starting year of 1995 is
    20.51 mm/y2, about 25 times the range shown for negative
    accelerations in Figure 1. RV compare their model to data as
    long as there are positive accelerations and do not continue the
    plot when accelerations become negative, which must happen
    for the overall record from1940 to 2001 to have an acceleration
    of approximately zero.”

    So who exactly, a priori, are assuming acceleration as the only possible answer, in the strict physics based sense anyways? HR are.

    “It is not possible.”

    Exactly, but only if you a priori choose a constant curvature (in time as the independent variable as opposed to temperature as the independent variable) quadratic term, which does not have a shread of physical basis whatsoever.

    HR then go on to suggest that RV only present data results (Figures 1 & 2) that support their modelling assumptions.

    But that is not the case, as HR so blatantly prove themselves, by choosing start years of 1985 (17 years of observational data) and even 1995 (now down to just 7 years of observational data).

    Seriously? Seriously!

    As RV rightly point out, these start dates are just too short, statistically speaking, to inform anyone about anything.

    “the folly of analyzing records shorter than approximately 60 years”

    Really? Really!

    “Houston and Dean (2011) considered only tide-gauge records with lengths greater than 60 years, noting that shorter record lengths are ‘‘corrupted’’ by decadal fluctuations.”

    So apparently, “tide-gage records” longer than 60 years are not ‘‘corrupted’’ by decadal fluctuations.

    Didn’t know that.

    So, according th HR, I cannot go O(120) or O(100) or O(60) or O(40), I can only go O(71) or O(80), or somesuch.

    I must use “tide-gage records” only and I must concentrate them CONUS, apparently.

    Are HR engaged in begging the question? You betcha!

    See my first post on the 87th CERB meeting, whence it was required that this be published in some form somewhere within the entire body of the peer reviewed literature, the outcome being this JCR publication.

    You see, the USACE needs better guidance on SLR than they have had to date.

    They’ll cherry pick which IPCC guidance the like and throw out IPCC guidance they don’t like.

    They’ll crerry pick an a priori quadratic curvature they like and throw out all other models they do not like.

    They’ll cherry pick the start year, the tide gages and their locations that they like and throw out all other data sources and timeframes they do not like.

    Whom better to “advise” the USACE on new and improved SLR guidance than the former (Director Emeritus) of the USACE ERDC and a former (Professor Emeritus) long standing CERB member themselves?

    Conflict of interest you say? You betcha!

    The USACE does not define, in and of itself, it’s own Mission Statements, those are accomplished only through Acts of Congress and the Executive branches.

    This has become a rather long post (but I’m not entirely done yet, there will be future posts if the moderators here would be so kind as to let them through), so I’ll end it right aboot here.

  16. 66
    One Anonymous Bloke says:

    #60 Simon Abingdon, yes it is rather subtle, but if I can understand it anyone can. The years along the bottom are start dates – think carefully what that means about the points on the line. (I think I have this right – please someone correct me if not!)

  17. 67
    t_p_hamilton says:

    Simon:”tph The x-axis does look rather like time and the blue line being shown as a smooth curve, your point must be one of some subtlety.”

    Yes, it LOOKS like time, it is NOT time (my original comment). Instead it is how many years worth of data (present – minus that date) to compute a single acceleration that spans the whole time period. That is why the error bars are larger for more recent “years” even though the measurements in recent years is more precise and more accurate (also two different things subtly different).

    [Response: Correct. -stefan]

  18. 68
    Ibrahim says:

    Maybe related?
    “the warmest year in the extended Greenland temperature
    record is 1941, while the 1930s and 1940s are the
    warmest decades.”
    Extending Greenland temperature records into the late eighteenth century
    B. M. Vinther,1 K. K. Andersen,1 P. D. Jones,2 K. R. Briffa,2 and J. Cappelen3
    Received 24 October 2005; revised 11 January 2006; accepted 28 February 2006; published 6 June 2006.

    The Antarctic (excluding the peninsula) didn’t realy warm since 1955 according to Giss and hadcrut.

  19. 69
    Paul S says:

    #64, NikFromNYC – The build-up of reservoirs has been gradual, as you can see on Church & White (2011) Figure 7, so both the ‘uncorrected’ and ‘corrected’ versions look pretty linear at a glance. Their detection of acceleration used the ‘uncorrected’ reconstruction, in case that is your concern.

    ‘That seems a bit odd, given that T has been rising in that same 150 years. Minus a mechanism for this avoided dip, the argument that actual sea level should be replaced by a virtual one is much less convincing.’

    According to the HadCRUT record the trend from 1850 up to about 1930 is flat. Real temperature increase occurred after this point. Could that be a reasonable mechanism for avoiding a dip?

    In order to build coherant long-term global records of sea level change some adjustments are necessary. The most well known is the correction for glacial isostatic adjustment – this is performed to ensure we are actually measuring the height/volume of the sea and not changes in height of the land.

    The Chao 2008 adjustment is different because it quantifies something that actually has affected the height/volume of the oceans. Whether a study uses the adjustment should depend on the focus. Church & White 2011 didn’t use it to draw their main conclusions because they were concerned simply with how sea level has changed. Conversely Vermeer & Rahmstorf (2009) is concerned specifically with how climate changes affect sea level, so it is imperative that non-climatic influences be taken into account.

  20. 70
    simon abingdon says:

    tph Thanks for the explanation. I have a question which may help me to understand, or not. If the x-axis were labelled in the reverse direction with more recent years (1970, fewer years’ accumulated data) on the left and earlier years (1870, more years’ accumulated data) on the right, the blue line would seem to be trending to about 0.02 mm/yr2, the presumably best result that 140 years of accumulated data can give us. (Sorry for wasting your time if this is hopelessly wrong.)

  21. 71
    Hank Roberts says:

    > CERB …
    > it was required that this be published in …
    > the peer reviewed literature, the outcome
    > being this JCR publication.

    For convenience, with applause, let me refer readers back to your earlier post. The academic publication was needed so regulations based on these assumptions could be arguably justifiable, to go on with stupid policies.
    They don’t need good science, just any basis to argue for continuing to do what they’ve been doing. That’s how it works.

    That earlier post is at:

    A brief excerpt:

    “… The seeds of their paper in JCR can be seem in the 87th CERB meeting;
    … read the Dean and Houston presentations as well as the discussion sessions including the comments from Mr. Headland.”

    The huge new industry now dedicated to “sand engineering” and “coastal nourishment” is in the service of real estate developers — fools building on sand islands that we have known for decades are moving.

    Thanks for a wonderful series of comments.

    Policy folks, look into this long story, folks, it goes back decades, has been reported on over and over, and continues in complete defiance of the science.

  22. 72

    Stefan.Did you considered the anthropogenic depletion of the aquifers?
    Can you give,please, an order of magnitude of the impact on the sea level?

  23. 73
    JCH says:

    alexandriu doru @ 72

    They discuss AGW depletion (what are the odds) in the rebuttal in JCR: starting with the last paragraph on page 785.

  24. 74
    Paul S says:

    #72, alexandriu doru – Church & White (2011) incorporates an adjustment for aquifer depletion into one figure and notes that it ‘offsets perhaps a third of [reservoir storage] over the last five decades’.

    Reservoir storage changes over that period have been estimated to have lowered sea level by about 3cm so that would mean 1cm of observed sea level rise over the past 50 years is attributable to aquifer depletion.

    I think it’s early days though. There will probably be a few papers on it over the next year.

  25. 75
    t_p_hamilton says:

    Simon, if the graph order of dates was reversed, then the graph would be the left-right mirror image. That said, the fit for the 100 year period 1870-1970 has the best value, about 0.016 mm/yr^2. This means that sea level rise, whatever it was around 1870, is now 1.6 mm/yr more (not a stretch given we are around 3 mm/yr now, and in order to get 1000 mm by 2100, that is an average of 10 mm/yr for the century – that means a significant acceleration is to come.

  26. 76
    Sekerob says:

    62 Kevin McKinney says: 13 Jul 2011 at 4:37 PM

    Just waiting on BPL to come around and write “Why Tilo Reber [Is Still, And Again] Wrong” if he even can be bothered to waste his time. It was a tactical apology [to shut him up in a OT, surely nowhere going polemic that could have ensued]… You know it, I know it, most know it, it makes diddely squad difference taking monthly or annual, provided there’s enough data points [years however sliced and diced] to draw meaningful conclusions from.

    (Posted in parts to find the partion that causes it to be flagged as spam.)

  27. 77
    Sekerob says:

    Entertaining is the new memê of Cryosat-2 being pre-heroed by the denial-ists, who’re hoping of course that it will rubbish all prior science. Maybe PIOMAS had it wrong, but would their trend change by any significance? No hope [for them] in heck. The team will have a new reference to refine their model, for it would be foolish to drop the effort… in case Cryosat-2 fails… it’s a limited mission after all and only numb-brains will put all eggs in one basket.

    Those of [willfully chosen mostly] limited capacitance will cling to 1998 as departure point [when cooling started], soon 2010, and the usual places that persist on drawing graphs from 2001 [with their cover-up act of ”randomly” switching to 20 or 30 years data… but then only when it suites them]

    No wonder what an Attack is on denialosphere scale. The super-sensitivity act when telling when their hair looks ruffled at the left ear, peddling the ”picture” of then it all being wrong :D

    PS, it is still baffling to take any series that started and ended just as BPL described at the beginning of his write-up, point 2 at top, and then 3 years later the subject ”bluffing” BPL was wrong.

    Sorry, too much spill of spiel in the head… wasting everyone’s time :P

    re CAPTCHA: flippancy. scomens

    (seems the filter did not like the alternate for horse manure)

  28. 78
    Dixon says:

    [Response: See above. You can cling to La Niña-related dips if it makes you feel better, but the long term trend is up. – gavin]

    So how long would I have to wait with the points at their current level before the CAGW hypothesis is falsified?

    [Response: Well, you’d first have to tell me what the ‘CAGW’ hypothesis was and what predictions are supposed to follow for sea level rise. Since I do not see this hypothesis defined anywhere in the IPCC report, I am not really clear what source you are referencing. Thanks. – gavin]

  29. 79
    Hank Roberts says:

    This may help put the issue clearly:

    By Orrin Pilkey, James B. Duke Professor Emeritus of Geology, Duke University
    Co-Author with Rob Young of The Rising Sea (Island Press)

    “Of all the various anticipated impacts of global climate change, sea level rise will likely be the first to produce a human catastrophe on a global scale….

    … the Intergovernmental Panel on Climate Change (IPCC) threw up their hands on this issue and in 2007 issued only a partial prediction. The panel said that sea level could be expected to rise 11 to 23 inches by the year 2100 but this number, they pointed out, included mainly thermal expansion and did not include the meltwater contribution from the great ice sheets. Unfortunately, many groups have mistakenly assumed the 11-to-23-inch prediction to be the total anticipated sea level rise. The IPCC is a committee of 2000 plus scientists, which perhaps explains the fuzzy wording of the sea level rise prediction that has led to widespread misinterpretation.

    Panels from various states and nations have since filled in the predictive gap and come up with their own predictions….”

    Here, I think, is Pilkey’s answer to Dixon’s question, the conclusion of that article:

    “… For the sake of the beaches we can only hope that a real retreat policy will be instituted and as communities are abandoned, their buildings will be demolished and removed. Otherwise we can expect that within 40 to 60 years, the world’s beaches will begin to be lined with debris from abandoned and deteriorating buildings providing much hazardous material to pollute the oceans.

    If our beaches are to survive for our grandchildren’s enjoyment, the time has come to plan the big withdrawal.”


    So, Dixon, you’re standing on the tracks and a train is coming: do you wait to see if it’s an illusion? Insist on your right of way? Do something to avoid being hit? What if it’s your grandchildren in harm’s way?

  30. 80
    SecularAnimist says:

    gavin wrote: “… you’d first have to tell me what the ‘CAGW’ hypothesis was …”

    I believe it is the hypothesis that at some point in the future, anthropogenic global warming (‘AGW’) will cause catastrophic (‘C’) effects.

    Like, for example, catastrophically destructive effects like record-breaking droughts, heat waves, flooding, violent storms, degradation of coral reefs, etc. occurring all over the world simultaneously, incurring billions of dollars in damages and negatively affecting agricultural output.

    I suppose one could say that the hypothesis that such events will occur in the future has been “falsified” since such events are already happening now.

  31. 81
    Hank Roberts says:

    I think Pilkey makes the point that it’s our preparation — or failure to prepare — that determines whether a catastrophe happens. That’s true more and more as the science informs our choices.

    Making bad choices is the catastrophe — it’s a human choice.

    “According to the book ‘Denial of Disaster: The Untold Story and Photographs of the San Francisco Earthquake and Fire of 1906,’ not only were the defects in earthquake and fire resistance repeated in the rebuilding, but “building code standards were actually reduced from those in effect before the Great Fire….
    … days after the earthquake, The Chronicle reported that the Real Estate Board resolved that the phrase “the great earthquake” would hitherto be known as “the great fire.”
    … seismic safety did not play as large a role in the rebuilding as one might expect. The primary focus was less ‘pre-quake’ mitigation (improving building and fire codes) than ‘post-quake’ preparedness (establishing a more robust system of water supply for firefighting).”

    Denial–it’s not just for earthquakes.
    It’s very often about real estate prices.

  32. 82
    SecularAnimist says:

    Hank Roberts wrote: “Of all the various anticipated impacts of global climate change, sea level rise will likely be the first to produce a human catastrophe on a global scale …”

    Well, I would submit that that hypothesis has already been falsified:

    Drought, flooding and other extreme weather events are already producing a human catastrophe on a global scale.

    Which does, I suppose, have an upside: coastal cities depopulated by famine will be easier to evacuate when they are eventually inundated by rising seas.

  33. 83

    Sekerob, “tactical apology”–copy that, but we *do* have The Borehole in effect, remember!

  34. 84
    Hank Roberts says:

    Sec, I didn’t write that; it’s a quote from the linked article.

  35. 85
    SecularAnimist says:

    Hank — I know. I meant to write “Hank Roberts quoted” but wrote “Hank Roberts wrote” out of mechanical habit and didn’t catch it until I had clicked the Submit button. Sorry ’bout that.

    Seriously though — it really does seem “likely” to me that agricultural failures resulting from AGW-driven megadroughts will be “the first to produce a human catastrophe on a global scale”, long before rising sea levels have a comparable impact.

    And indeed, this is already happening on a continental scale in Africa, and the impact of unprecedented, intense, prolonged droughts on agriculture in Russia, China, Australia, and elsewhere is already impacting the world’s food supply.

    And it seems entirely possible that acceleration and intensification of such droughts could lead to world-wide crop failures in a matter of years, rather than decades. We could be literally just a few years away from an unprecedented global famine, which makes it hard for me to get worked up about the possible impacts of sea level rise a century from now.

  36. 86
    EFS_Junior says:

    With people like these, do we really need enemies?

    (This is directly germane to Houston and Dean and their previous publically held opinions as expressed through their writings in the ASBPA and FSBPA.)

    It starts right aboot here, (CERC-95-4) “The Economic Value of Beaches” by James R. Houston);

    And ends (to date anyways, except for the aforementioned thread topic) right aboot here (The ASBPA’s Shore & Beach Vol. 76, No. 4, pp. 22-26), “The economic value of beaches – A 2008 update” by James R Houston);

    There’s even an ASBPA PR with this one (“New Study shows beaches are a key driver of U.S. economy”;

    There is some in between stuff though;

    THE ECONOMIC VALUE OF BEACHES A 2002 UPDATE (S&B, V70, N1, pp. 9-12) by James R Houston




    INTERNATIONAL TOURISM AND U.S. BEACHES (S&B, V64, N2, pp. 3-4) by James R. Houston

    COASTAL FORUM I. BEACH NOURISHMENT (S&B, V63, N1, pp. 21-24) by James R. Houston

    Conflict of interest, you say? You decide. :(

    And what does Robert Dean have to say aboot all this through the auspices of the FSBPA, you say?

    Wait for it, you guessed it, a BAU policy (move along, nothing to see here, it’s all just a scare tactic), why heck, the Dutch, and even Dubai, are building into the oceans, so heck maybe we should also (by implication);

    But wait, the lead author, Todd Walton appears to have (admittedly slightly) moved the goal posts somewhat from his earlier views;

    (The opinions expressed in this article do not necessarily represent those of FSBPA) (downloadable PDF)

    So is the ASBPA’s Shore & Beach a peer-reviewed journal? Why yes, err, sort of, as they themselves state;

    But apparently anyone can “volunteer” to be a peer reviewer;

    and I quote;

    “ASBPA peer reviews every article that is published in Shore & Beach journal. We need peer reviewers with a wide range of expertise. In addition to qualifications, it is important to understand that timeliness is critical. We will let you know ahead of time when articles should be expected, but they need to be turned around in a week’s time period if at all possible. Slow peer review means the journal is delayed. If you are interested in being a peer reviewer, please fill out the form below:”

    So yes, you too, can be a peer reviewer of S&B.

    But dag nab it, hurry up aboot it, time’s a wastin’, we have beaches to fill (with buildings and people and things and very much mulla thank you very much, oh, and lest we forget, sand, lots and lots of sand, enough sand to last the eons, and if sand won’t work, we’ll build sand berms (think CCC), and sand fences, and geotextiles, and levees, and dykes (no, not those types of dykes, get your filthy mind out of here right aboot now), and retaining structures, and walls made of straw, no make that walls made of sticks, no make that walls made of bricks, no make that walls of concrete and steel, and even dams, dam it) and what not.

    So what does S&B’s peer review consist of you say?

    Well it’s right here;

    in a nice Q&A fill in the blanks type of peer review (with much space left over for comments even ;-).

    Now go to the ASBPA’s links section, see the first two links? Hmm, are they just playing politics, or policy, or science? You decide. :(

    The ASBPA even has a nice “The Beachonomics Quiz” right aboot here;

    (Choices are numbered, answers are lettered, what’s up with that?)

    Why yes, you too can strive to flip burgers at a beach near you, after all, we’re just a service economy nation now anyways, or so I’ve been told, many a time, by the MSM. Life’s a beach after all, right? :(

    Well I have my own one question quiz, called The Paintonomics Quiz;

    You are aboot to paint a room that has only one entrance/exit (no windows or axes or explosive devices or etcetera’s), four corners, one of those four corners has a hole in the floor, which below it contains shark infested waters (but you don’t know this for sure, as you’ve never ventured into this corner, even at the pleading of many others, for you to do so for your own safety), do you;

    1) Paint your way to safety (via the entrance/exit, call this one mitigation).
    2) Paint yourself into one of the three corners sans the hole (call this one BAU) and wait for the paint to dry (timescale O(100) years).
    3) Paint yourself into the corner with the hole, look down, see only dark waters, and say, aw, what the heck, I can swim, and time’s a wastin’ anyways, gotta go (call this one adaptation, of the worst sort, mind you).

    Hmm, which to choose, well I wasn’t born three days before The Day After Tomorrow (BTW, Al Gore’s favorite film, or so I’ve been told at WUWT (I kid, I kid)) you know, so I would choose A (in keeping with the ASPCA nomenclature, mind you).

    Wow, another rather long post (but I’ll have more to say (further critiques on the HD paper, as well as current (actually expired as of July 1, 2011) USACE SLR guidance (EC 1165-2-211 for those of you who want to jump ahead).

    DISCLAIMER: I do not now currently work for the USACE in any capacity, the views expressed here are my own (except for the cited documents which are the works of others), and my real name is Francis E. Sargent (most people call me Frank, but my birth name is Everett F. Sargent, Jr., thus the EFS_Junior screen name (moderators, fell free to edit out my true identity as you so see fit, but I have nothing to hide)).

  37. 87
    JCH says:

    EFS – just a layperson here. I think it’s ironic that many of the skeptics who tout Houston and Dean’s SLR study in blog comments also complain incessantly about people choosing to live on floodplains or areas commonly battered by hurricanes.

    Also, in the 1970s I lived in my Uncle’s beach house on Emerald Isle. At that time there still was a lot of open land. It was a short walk to a live-oak forest. His house was a former USMC barracks building. When I went back in the 1980s, there were expensive homes as far as the eye could see. Took all the fun out of it, and I’ve never gone back.

  38. 88
    Hank Roberts says:

    > for those of you who want to jump ahead

    sample from the first page of hits:
    Don’t miss the errata sheet, so your calculations come out as they should.

    Lovely charts and graphs:

  39. 89
    JCH says:

    Hank, on the lovely charts and graphs, compare Hansen-Sato page 15. The H-S graph is showing the vast majority of a 5 meter rise as occurring in the latter half of the 21st century. I have no way of knowing the correct presentation, but to me that seems a more reasonable presentation of the how SLR will play out. Whether the final number is less than 1 meter or greater, graphs that show a pronounced take off in next few years look wrong to me. Hansen’s curve shape makes more sense. If there isn’t a certain number by 2017, I can just hear the blog hooting to call whole thing off.

  40. 90
    Hank Roberts says:

    JCH, I gave that link as an _example_ of what you can searching on the publication that EFS_Junior says will be worth looking into further.

    > I have no way of knowing … but to me it seems

    You’re illustrating an error scientists work hard to avoid.

  41. 91
    Hank Roberts says:


    Recent changes in the Earth’s oblateness driven by Greenland and Antarctic ice mass loss

  42. 92
    George Ennis says:

    Stefan, I am not a scientist, although I do have a background in the identification and measurement of risk. I just wanted to let you know after reading some of the comments on here and your responses that Job is being asked to return the award for patience since there is obviously a better candidate for the prize; you.

  43. 93

    #91 Hank, I know some are shy to say this, but I don’t believe that mass transfers in the Gigatons have no effects on plate tectonics. At least I think so. As we “Humanform” the planet further it will be quite a different world. I read 36 gigatons a year from glaciers to oceans.

  44. 94
    Jeff Jones says:


    What cities are currently being depopulated by famine or other catastrophes?

  45. 95
    Hank Roberts says:

    Jeff, you misread that
    > coastal cities depopulated by famine will be
    > easier to evacuate when they are eventually …
    but I think it’s herring bait for this topic

    Sea level rise allows time to plan for dismantling what can’t be protected along the coasts. Hard to imagine us being smart enough for the long term, isn’t it?

  46. 96
    sidd says:

    Mr. Davidson wrote expressing his concern that ice melt might affect plate tectonics. I doubt this is the case because movements of plates on the order of centimeters a year such as cause the Boxing Day earthquake a decade ago or the Sendai more recently represent far larger momenta and energies than are involved in either ongoing isostatic rebound from the last glacial maximum or the effects of current ice melt. I fully expect India to keep invading Asia for example, as she has through several stades.

  47. 97
    Pete Dunkelberg says:

    @ 79 Hank quoting Orrin Pilkey ““Of all the various anticipated impacts of global climate change, sea level rise will likely be the first to produce a human catastrophe on a global scale….”

    Not at the snail’s pace predicted here. Climate disruption is coming on much faster. Floods, droughts, heat waves, that sort of thing. Then ocean acidification. Then no food for a billion people. Fossil fuel profits high though.

  48. 98
    Ricki says:

    You are correct about the plate movements, but the triggers to release the stresses are another thing. Re-distribution of the mass will cause changes in the temporal patterns of earthquakes, not where they occur.

    Unfortunately, sea level rise is not going to be a gradual thing. We will see big impacts when coastal storms occur, so the damage to property will not be a gradual thing but a sudden thing.

  49. 99
    Martin Vermeer says:

    SecularAnimist #85, you are quite right that sea level rise is just one of a number of potential impacts due to AGW, and not the most short-term urgent one. Yet when you say “which makes it hard for me to get worked up about …” I think you fall victim to an optical illusion.

    It is the same optical illusion that those people fall for that think it is enough to bring emissions to zero in order to stop AGW; of course it isn’t, that will only stop the rise in atmospheric concentrations, and temperature. With sea level it is one level worse still: even stopping the rise in temperatures will not stop sea level rise, only make it continue indefinitely, humanly speaking forever. It’s like the tired old metaphor of an ocean liner heading for an iceberg taking a long, long time to change direction.

    Now, while it unfortunately is impossible to rule out a calamity in the near term that would completely wipe out civilization, I don’t think we should base our planning on assuming this: there likely will we a human civilization over the remainder of this century, fighting a witches’ brew of climate and other impacts on a resource-depleted planet. Major sea level rise will be one more ingredient, and one which at that point in time can no longer be usefully mitigated. That we should have been doing now.

  50. 100
    Hunt Janin says:

    I have the strong imprssion that only two countries — the Netherlands and the UK — are now making any national efforts to deal with future sea level rise. Know of any others?