Is Sea Level Rise Accelerating?

Guest post by Paul Homewood

 

image

 

It is generally accepted that sea levels increased during the 20thC at a rate of about 185mm or about 7”. Furthermore studies suggest that there was no acceleration in this rate during that time. One of the best known studies was by Bruce Douglas, who produced the above graph from Tide Gauge records for 23 geologically stable sites.

Satellite monitoring of sea level, which began in 1993, however, shows that the current rate of increase is about 2.8mm/year.

image

 

So, question – has the rate of sea level rise really accelerated in the last two decades. In this study, I will be extending Douglas’s work up to 2011 to find out.

 

 

 

Methodology

Douglas based his work on tide gauge records from PSMSL, (The Permanent Service for Mean Sea Level), and used the following criteria :

  • Each record should be at least 60 years in length
  • Not be located at collisional plate boundaries
  • At least 80% complete
  • Show reasonable agreement at low frequencies with nearby gauges sampling the same water mass
  • Not be located in regions subject to large post glacial rebound. 

    He subsequently identified 23 sites that met these criteria. (These are listed in Appendix A). The tide records at each site were adjusted for any post glacial (isostatic) rebound, i.e any rise or sinking of the land, so as to isolate the eustatic sea level, i.e. the quantity of water in the ocean.

    Of Douglas’s 23 sites, only 12 have full or nearly full records since. (Newlyn’s records go up to 2009, but are included). From these 12 stations, I have reconstructed the Douglas graph.

    A point I will keep emphasising is that I am not trying to establish “the actual amount of sea level rise”, but am looking to quantify “the relative rate of change”. In other words, is the current rate of rise greater (or smaller) than the rise during the last century.

    Bearing this in mind, my reconstruction is not adjusted for isostatic rebound. There are two reasons for this :-

    1) Any such adjustment is adding a certain amount of subjectivity, which is absolutely not necessary.

    2) As the objective is to compare the rate of sea level change between 1900-2000 and 2001-2011, the isostatic factor is irrelevant, as it is, to all intents and purposes, a fixed amount.

     

    Reconstruction

    Figure 1 shows the spaghetti graph for each station, which naturally does not tell us a huge deal. However Figure 2 averages all twelve stations together, with a cumulative three year running average plot, exactly as Douglas did.

    image

    Figure 1

    image

    Figure 2

    Two things stand out :-

    1) The new reconstruction indicates a sea level rise from 1900-2000 of 168mm, actually a pretty good fit with the original Douglas calculation of 185mm. The difference between the two datasets can be ascribed to two factors :-

    a) No adjustment for isostatic rebound in the new reconstruction.

    b) The elimination of the 11 stations, which do not have recent records.

    We have already discussed isostatic rebound and this does not affect the trend line of the graph one way or the other.

    As for the reduction in the number of stations, Appendix A shows that there are now no Southern Hemisphere sites in the new dataset. Could this be skewing the average? More on this later, though.

    2) The sea level rise has stuck pretty close to the long term trend (red line), both throughout the record, but more significantly in the last decade. This is our first indication that there has been no acceleration in the trend, at least in these 12 stations. Contrast the last decade, for instance, with the period 1940-60 when levels were consistently rising faster than trend.

    Before we look more closely at the figures, it is worth remembering that the three year average used above combines both the 2011 La Nina and the 2010 El Nino in the 2011 average, thus smoothing out any ENSO variability. (With no such smoothing, the 2011 figure would show a sharp drop.)

     

    A closer look

    We don’t have to rely on eyeballing the graph in Figure 2. Figure 3 shows the year on year changes in sea level (rather than the cumulative change).

     

    DOUGLAS UPDATE_htm_m55835242

    Figure 3

    While there is considerable inter annual variability, the 10 year running average indicates no upward trend. But we can actually go one step further, by focusing in on the 10 year average and therefore a much smaller range, as shown in Figure 4.

    DOUGLAS UPDATE_htm_ef9a71a

    Figure 4

    The red line is the trend and actually shows a small decline since 1900, although the last 10 years are slightly higher than trend at 2.15mm/year. However, the 10 year figures are comparing 2011 with 2001, when sea levels were lower than usual, having declined for two years, as Figure 2 illustrates.

    Figure 5 gives a broader perspective by listing the average annual increase to 2011, depending on which start year is selected.

    Start Year mm/yr increase to 2011
    1990 2.20
    1991 1.41
    1992 0.23
    1993 1.00
    1994 1.44
    1995 0.35
    1996 1.09
    1997 -1.08
    1998 0.65
    1999 0.78
    2000 1.89
    2001 2.15

    Figure 5

     

    Bearing in mind the increase in the 20thC was 1.68mm/yr, there has been nothing unusual in trends since the 1990’s, regardless of which year you compare with. Indeed, the evidence would suggest a declining trend.

     

    Southern Hemisphere

    As previously mentioned, the reconstruction now includes no Southern Hemisphere sites, with three New Zealand sites (Auckland, Dunedin and Lyttleton) and two Argentine sites (Buenos Aires and Quequen) disappearing because of the lack of recent records. Could the recent trend be biased because of this?

    Although there are now no sites with records back to 1900 in the Southern Hemisphere, there are a few with continuous records since the 1960’s. In New Zealand and Argentina, Wellington and Palermo respectively fit the bill. To these I have added two Australian stations, Port Adelaide and Port Lincoln. There are no such records available in other Southern Hemisphere countries. The sea level changes are plotted in Figure 6 and make interesting reading.

     

    SOUTH HEMISPHEE_htm_m557ab7ee

    Figure 6

    There is a clear decline in the trend, which the actual figures emphasise. Between 1966 and 2000, sea levels rose by 2.99mm/year, at the four stations averaged together. (1966 is the earliest year that we have records for all four sites). By comparison, between 2000 and 2010, they actually fell by 1.73mm/year. Furthermore, because there are no records for any of these sites in 2011, the plot finishes in 2010, when global sea levels appeared to be higher than normal.

    In other words, the exclusion of Southern Hemisphere stations, far from causing the reconstructed sea level trends to be understated, seems to have had the opposite effect. (For the record the New Zealand and Australian stations show falls since 2000, whilst Palermo shows an increasing trend).

    Let me make this clear. I am not claiming this small sample is representative of the Southern Hemisphere as a whole. But I would claim that it is a reasonable substitution for the stations excluded from the original Douglas study.

    Church & White

    In 2011, John Church and Neil White published their paper, “Sea Level Rise from the Late 19th to the Early 21st Century”. This attempted to reconcile sea level measurements from tide gauges and satellites. They concluded that between 1993 and 2009, sea levels rose by 3.2mm and 2.8mm per annum as measured by satellites and tide gauges respectively, as shown below in Figure 7.

     

    MediaObjects/10712_2011_9119_Fig4_HTML.gif

     

    Figure 7

    Global average sea level from 1990 to 2009 as estimated from the coastal and island sea-level data (blue with one standard deviation uncertainty estimates) and as estimated from the satellite altimeter data from 1993 (red). The satellite and the in situ yearly averaged estimates have the same value in 1993 and the in situ data are zeroed in 1990. The dashed vertical lines indicate the transition from TOPEX Side A to TOPEX Side B, and the commencement of the Jason-1 and OSTM/Jason-2 records

    Two things stand out though.

    1) 1993 is used as the starting point (being the start of the satellite record). However, as Church and White themselves point out :

    “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. “

    In other words, the trends have been calculated from an abnormally low point in the long term record. (Shades of 1979 and satellite temperatures!). This dip can be seen very well on the original Douglas graph, shown again below.

     

    image

     

    2) The exercise stops in 2009, when sea levels were at a cyclical peak, as confirmed by both satellite records and tidal gauges.

    So Church and White are comparing an unusually low point in the cycle with an unusually high one. Of course, their choice of dates was purely circumstantial, but, particularly over such a short period of time, such a choice of dates renders their results pretty meaningless. (Figure 5 shows just how much difference the choice of start dates can make). Satellites suggest a drop of 5mm from 2010 to 2011. Based on this, Church and White’s tidal gauge estimate of 2.8mm/year becomes 2.2mm/year, from 1993 to 2011.

     

    Is 2011 unrepresentative?

    Both satellites and tide gauges confirm that sea levels fell in 2011 with La Nina. So, is using 2011 as the end year disguising an accelerating trend?

    I would answer this in two ways :-

    1) As previously mentioned, I have opted for a 3 year average, in order to replicate the Douglas exercise. This has conveniently averaged together the 2009/10 El Nino and the 2010/11 La Nina within the 2011 “3 year average”, and consequently giving a robust underlying number. (Over the next two years this number should decline as the 2009 and 2010 figures are removed from the average, assuming, of course, no new El Ninos).

    2) I have also shown 10 year averages, which to some extent dilute and smooth out  changes in a single year. (For interest, if sea levels in 2010 and 2011 are averaged together in the reconstruction, the 2011 figure is increased by about 10mm. If the average annual increases in Figure 5 were calculated against the 2010/11 average, the increase since, for example, 1993 would be 1.56mm/year , instead of 1.00mm).

     

    Conclusions

    In the reconstructed analysis, there is no evidence of an acceleration in the long term rate of sea level rise, which remains at below 2mm/year. Furthermore an analysis of Southern Hemisphere sites suggests a slowing down in the rate. The sample sizes in both cases are small and give limited geographical coverage. Nevertheless, they give a similar coverage to the original Douglas study, which has generally been accepted as giving an accurate assessment of 20th Century rise. (For instance, the IPCC quote a figure of 1.7mm/year).

    The divergence with satellite data can, logically, only be due to one or more of the following factors :-

    1) The original Douglas study is based on an unrepresentative sample or inaccurate records. If this is so, it would suggest that the rise of 1.85mm/year, that Douglas calculated for the 20th Century, is significantly understated.

    2) Satellite measurements are wrong.

    3) The relatively short satellite record is too short to give a accurate long term trend, particularly as it starts at a low point in the cycle.

    4) The exclusion of 11 stations from the reconstruction has reduced the true rate of sea level rise. It would appear, however, hugely unlikely and coincidental that these 11 stations had a rapidly increasing trend, while the other 12 showed no trend change at all. In any event, we have seen that this is not the case in the Southern Hemisphere analysis.

    One final comment. From this study, it appears that the number of reliable tidal gauge sites, with reasonably long and complete records, is on the decline. Is too much reliance being put on satellites? Maybe. But when sea level rise is such an important and controversial topic, I find it both astonishing and rather sad that this is being allowed to happen.

     

    References

    1) PSMSL data is available here.

    2) Further information is available from the University of Colorado Sea Level Research Group.

    3) Details of the Bruce Douglas study are here.

     

    APPENDIX A

    LIST OF SITES

    Location Country/State Sea Level
    mm
    2000
    Sea Level
    mm
    2011
    Increase
    mm/yr
    1900-2000
    Increase
    mm/yr
    2000-2011
    Trieste Italy 7060 7070 1.44 0.91
    Santa Monica CA 6996 7011 2.19 1.36
    San Francisco CA 7050 7086 1.53 3.27
    San Diego CA 7059 7115 1.49 5.09
    Marseilles France 6990 7035 0.82 4.09
    Fernandina FL 7262 7225 2.22 -3.36
    Brest France 7133 7115 1.97 -1.64
    Honolulu HI 7044 7068 1.36 2.18
    Key West FL 7211 7215 2.16 0.36
    Newlyn UK 7097 7157 1.46 6.66
    Pensacola FL 7064 7095 2.51 2.82
    La Jolla CA 7060 7104 1.63 4.00
    AVERAGE 1.68 2.14

    LIST OF SITES ORIGINALLY IN DOUGLAS, BUT EXCLUDED DUE TO LACK OF RECENT RECORDS

    Location Country/State
    Auckland NZ
    Balboa Panama
    Buenos Aires Argentina
    Cascais Portugal
    Cristobal Panama
    Dunedin NZ
    Genoa Italy
    Lagos Nigeria
    Lyttleton NZ
    Quequen Argentina
    Santa Cruz Tenerife
About these ads
This entry was posted in Sea level and tagged , , , , , , , . Bookmark the permalink.

139 Responses to Is Sea Level Rise Accelerating?

  1. mikelorrey says:

    It should be obvious that if the southern hemisphere has zero sea level change, and all the sea level change is in the northern hemisphere, that that change is all due to post-ice-age rebound issues, period.

  2. Leg says:

    Paul: Thanks for the article. For some reason I was not fully aware of the variability of the sea level from year to year and your graphs show that clearly. Would you or someone kindly illuminate me as to the theorized reasons for the variability? I suspect the heating and cooling cycles of the oceans plays a large role, but what else influences the variability?

  3. gerrydorrian66 says:

    Again thanks for the debunking of more lies by the Establishment. The thing is, if they’ve read their Republic, they’ll know that truth (says “Socrates”) is subservient to political purposes; by which definition the real inconvenient truths are the ones we tell, the ones that schoolchildren and students are not to be allowed to hear.

  4. crosspatch says:

    What I can’t understand about tide gauges is why it is so difficult to make them. For example, it should a fairly simple matter to do something like place a device on the Golden Gate bridge that has a GPS device that knows its current altitude and can determine the distance to the surface of the water below. There are many other such bridges, the Chesapeake Bay Bridge Tunnel would be a perfect example. You can account for any changes due to changes in altitude of the measuring device and get an accurate measurement to the surface of the water below. Having a network of tide gauges on bridges over salt water shouldn’t be a huge problem, I wouldn’t think.

  5. Brian H says:

    H/T to me (I think). ;)

    The manufacture and marketing of trends is particularly prominent in CS-oceanography. The underwater cabinet meeting will be an embarrassment for the ages!

  6. Juraj V. says:

    Personally, I have yet to see a photo before-after of some harbor or cliff, which shows higher sea level today than in 1900 or so. So far, I have seen none but saw a lot of pictures, which looks about the same.

  7. phlogiston says:

    No. Its decelerating.

  8. Kelvin Vaughan says:

    Start the graph in 2011. Wow it’s going up a lot faster now! Looks about 10mm a year.

  9. shortie of Greenbank says:

    I would say, just from looking at the list, that it is too small a list due to it being concentrated in only a few geographical areas, France, CA or I gather California and FL or Florida.

    Then you look at the numbers and few of these geographically close locations are the slightest bit similar to each other in results.

    Newlyn in the UK, must be hell since 2000…….

  10. Harriet Harridan says:

    Poorly written introduction: “It is generally accepted that sea levels increased during the 20thC at a rate of about 185mm (1.85mm/yr)….. Satellite monitoring of sea level, which began in 1993, however, shows that the current rate of increase is about 2.8mm/year.”

    So sea level is accelerating – and then you claim it’s not. Lose the “However” to make the intro make sense.

  11. Jens Bagh says:

    Were sea levels to be rising this would slow down the rotation of the earth. Has any change been noted in the rate of change of rotation and if so how does this compare to the present study?

  12. Philip Bradley says:

    To quantify the impact of volcanic eruptions we average monthly GSL data from 830 tide gauge records around five major volcanic eruptions. Surprisingly, we find that the initial response to a volcanic eruption is a significant rise in sea level of 9 ± 3 mm in the first year after the eruption. This rise is followed by a drop of 7 ± 3 mm in the period 2–3 years after the eruption relative to preeruption sea level. These results are statistically robust and no particular volcanic eruption or ocean region dominates the signature we find. Neither the drop nor especially the rise in GSL can be explained by models of lower oceanic heat content. We suggest that the mechanism is a transient disturbance of the water cycle with a delayed response of land river runoff relative to ocean evaporation and global precipitation that affects global sea level. The volcanic impact on the water cycle and sea levels is comparable in magnitude to that of a large El Niño–La Niña cycle, amounting to ≈5% of global land precipitation.

    http://www.pnas.org/content/104/50/19730.full

    Volcanic eruptions increase precipitation, then decrease it. Presumably because the aerosols seed precipitating clouds, and reduce solar insolation and hence ocean evaporation.

    The mainstream argument that volcanic eruptions reduce solar insolation and reduce thermal expansion of the oceans was never plausible.

  13. Ecotretas says:

    Good work!
    I had noticed the same 3 years ago, when I did a little study on the same issue. It is a pity that Cascais, in Portugal, one of the oldest in the World, isn’t being recorded… I used 53 stations then, with the same criteria as Douglas. Please see at:
    http://ecotretas.blogspot.pt/2009/07/sea-level-decline.html
    The complete report is at:
    http://www.slideshare.net/Ecotretas/sealevel-1792065

    Ecotretas

  14. Spector says:

    I wonder if the satellite measurements are referenced to the center of the Earth or some average ‘Land Level’ that could reflect gradual minor changes in the effective radius of the surface of the Earth due to minor changes in the average interior temperature of the Earth.

  15. Agnostic says:

    I found this to be an extremely interesting and balanced post. Clear about what is being claimed and what is not being claimed., with justifications and pointing out possible problems. Also, very clearly written and easy to digest. Thank you.

  16. jh says:

    Point of information.
    How does the eruption of a volcano affect measured rise in sea level?

  17. polistra says:

    I don’t know why anyone would even think that a mathematically-adjusted “measurement” from thousands of miles out in space should compete with a painstakingly careful direct measurement of the real thing! The direct measurement should instantly replace all simulations.

  18. Bloke down the pub says:

    Comparing the figures for Newlyn with those of Brest, it seems odd that while their older rates of change were similar, the recent rates have diverged with Brest going negative and Newlyn strongly positive. As comparatively close sites which might be expected to keep in step, I wonder if the reason that Newlyn stopped reporting was that it had started to subside?

  19. richard verney says:

    It does not appear, from observational evidence, that sea level rise is accelerating, or at any rate, not to any alarming extent. From observational evidence, there is little reason to be concerned as to sea level changes in the next 100 or so years.

    It would be interesting to see the following plots:

    1. estimated annual sea level change due to estimated glacier melt, plotted against observed sea level change.
    2.estimated annual sea level change due to observed sea temperature, plotted against observed sea level change.
    3.estimated annual sea level change due to estimated glacier melt and observed sea temperature change, plotted against observed sea level change.
    4. estimated sea level change due to estimated isostatic rebound, plotted against observed sea level change.
    5, plots 1 to 3 above but ‘adjusted’ for estimated annual isostatic rebound.

    It is important to get a grasp on why sea levels are changing (if they are indeed changing) and to what extent this truly correlates with conjecture, ie glacier melt and thermal expansion.

  20. AllanJ says:

    Nice report.

    CAGW theory says there is a link from carbon dioxide to global warming to ice melting to sea level rise. Implicit in this report is the question of whether sea level rise has accelerated in response to the late twentieth century rise in atmospheric CO2. Mr. Homewood has confined himself to the data. I will speculate beyond the data to say that this report would seem to be another pretty solid “fail” for CAGW theory.

  21. AJ says:

    It looks like, as in politics, all sea level rises are local.

  22. Otter says:

    Bloke down the pub~ please keep us aBrest of the situation!

  23. Mike Jonas says:

    Just how alarming are these sea level rises of less than 2mm pa?

    Global sea level rose by about 120 m during the several millennia that followed the end of the last ice age (approximately 21,000 years ago)…” IPCC report AR4 FAQ 5.1
    That’s 5.7mm pa. More if you take out the last 2,000 years when they say it stabilised. They also say the 20thC rise was about 1.7mm pa.

    Global average sea level was likely between 4 and 6 m higher during the last interglacial period, about 125,000 years ago, than during the 20th century…” IPCC report AR4 TS.3.5
    At 1.7mm pa – OK say 2mm pa – it would take 2,000 years to rise 4m, ie. to the height of 125,000 years ago. We will be running out of fossil fuels in just a fifth of that time, maybe even less.

  24. M Courtney says:

    Bloke down the pub says:
    May 16, 2012 at 2:32 am
    You ask about Newlyn’s accelerating sea level rise.

    Just a thought but the National Trust has started (about 2008) to concrete in the causeway to St Michael’s Mount (just around the bay). I’ve thought that fixing the rocks down, instead of letting the sand flow beneath as the Victorians did, was likely to cause a change in the flows. Although the need to do that may be indicative of a change anyway.

    Perhaps the tides in the bay have been changed.

  25. spangled drongo says:

    I live in the southern hemisphere and a waterfront house property of an uncle and aunt where I stayed as a boy in 1946 used to have the king tides come up on the lawn [it was flat, low lying land]. I was talking to my cousin a couple of days ago and he still lives in the same area but a different house. He has been a keen boating man all his life and he said that the king tides do exactly the same thing at the old house sealevel-wise that they did 66 years ago. He cannot detect any change in SLR.

  26. Geoff Smith says:

    What is the point of posting this when you have posted several other articles discussing how there has been NO rise in sea level.
    I am finding this site is going around in circles and getting to bogged down in political crap

  27. @Bloke Down The Pub

    Comparing the figures for Newlyn with those of Brest, it seems odd that while their older rates of change were similar, the recent rates have diverged with Brest going negative and Newlyn strongly positive.

    I guess this shows just how variable sea level can be in the short term. In the 1990’s, sea level was falling at Newlyn, so in comparing 2009 with 2000, we are comparing to an unusually low year.

    The rate of increase over, say, 20 years shows nothing unusual happening.

    BTW – Newlyn is sinking at about 1.1mm/yr.

    http://notalotofpeopleknowthat.wordpress.com/2012/04/16/sea-level-changes-at-newlyn/

  28. 3mm a year ? an Australian expert disagrees
    – You can listen to a podcats from the Alternate Reality,
    Climate Commissioner : Tim “Wrong-Again” Flannery told us “in the next DECADE ‘or so’ we will see significant sea level rise of UPTO a metre”

    10’30” in to the podcast

    …… (note “the get out of FAIL phrases” : ‘or so’ & UPTO)
    – he said that just after being asked about his OWN waterfront house
    (I paraphrase) “my property is 6m above the water” … “it won’t be effected for thousands of years”

  29. Ian W says:

    The La Nina of the El Nino Southern Oscillation is caused – so Bob Tisdale tells us – by upwelling of cold water due to winds pushing the hotter surface water of the equatorial Pacific to the West. The El Nino is the warm surface water returning in a Kelvin wave to the East. If this is the case ENSO does not alter the actual volume of the oceans merely the distribution of warm and cold waters in the equatorial Pacific. Why is it that the different mixing of warm and cold water in the equatorial pacific should show up as a rise or drop in ‘global’ seal level?

    It appears illogical.

  30. Baa Humbug says:

    Pretending to measure sea (ocean) levels to millimetres and fractions of millimetres on a monthly and yearly basis is at best a statistical hobby.

    Sea levels take millenia to change enough for anyone to worry about. No decision maker is going to make decisions about what may or may not happen in hundreds of years time.
    The sea level rise meme is just plain stupid waste of time.

  31. Paul S says:

    When putting together a tide gauge ensemble in order to err.. gauge recent sea level trends it’s a good idea to check against the satellite data to see if your station choices are representative of recent regional patterns of sea level change:

    http://www.aviso.oceanobs.com/fileadmin/images/news/indic/msl/MSL_Map_MERGED_Global_IB_RWT_NoGIA_Adjust.png

    One third of your stations are situated in California, which has seen a small negative sea level trend since 1993. You have zero stations around Australia, East Africa or South East Asia: a larger portion of the world which has seen sea level rising much faster than the global average. The fact that this ensemble doesn’t contain recent acceleration is, unfortunately, meaningless if you want to talk about global sea level trends: the sample is simply not representative.

  32. Jimbo says:

    But…….but……the glaciers are melting (worse than we thought), thermal expansion has kicked in, snowpack / ice cover is in rapid decline so you must be wrong. There has to be an acceleration – all that melting ice has to go somewhere.
    /END SARC.

    Message for Warmists: The IPCC finds no evidence of acceleration. All the scare stories are based on IF and climate models. Observations win every time.

  33. Ian_UK says:

    In a debate in the UK parliament last night, the leader of the Green Party stated that the British government is planning to upgrade the Thames Barrier to cope with a projected (IPCC, of course) sea level rise of 1.9m. The above report (and similar studies) suggest this would be a waste of money. I’ve written to my MP asking if the story’s true, if so, how much it will cost and what due diligence the government has carried out to justify the expense. I don’t expect to get a sensible answer, though.

  34. Dave says:

    I have a hard time believing that sea level rise can even be measured using tide gauges. The surface area of the world’s oceans and the topography of its bottoms are in a state of constant change due to plate tectonics. Undersea volcanic activity also displaces water. To assume that these processes have no effect on sea level as measured by a mechanical gauges fixed at (slowly) moving locations seems a bit naive to me. How does one separate the signal from unquantifiable changes to the volume of the oceans from the increase in sea height due to melting glaciers? I would put more stock in satellite measurements.

  35. Latitude says:

    Like UHI, satellite measurements are added to…..
    satellites fall out of orbit…..you would subtract not add
    Then an additional addition for the ocean floor sinking……………../snark

  36. knots340 says:

    Why is no one doing the obvious? The data is in the form of sea level vs time, so take the derivative which gives the velocity in mm/year; which is the slope of the trend line. Next take the second derivative which will give the acceleration. What is that value? I would guess, given an almost perfect straight line fit to the data, that the acceleration is very close to zero.

    This is just elementary calculus. Reminds me of what Prof. Brown said in a previous thread of people doing analysis that would not even yield a passing grade in intro. calculus.

  37. @ Richard Verney

    It would be interesting to see the following plots:

    1. estimated annual sea level change due to estimated glacier melt, plotted against observed sea level change.
    2.estimated annual sea level change due to observed sea temperature, plotted against observed sea level change.

    Back in 2006 Bruce Douglas put out a paper which suggested the “theoretical” sea level increase (as caused by melting glaciers, thermal expansion etc) was actually less than the tidal gauges suggested.

    http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/RateAndCauses.pdf

  38. @ Paul S

    The fact that this ensemble doesn’t contain recent acceleration is, unfortunately, meaningless if you want to talk about global sea level trends: the sample is simply not representative.

    The aim was to replicate Bruce Douglas’s study, not to create a new global assessment.

    Incidentally sea levels at Port Adelaide and Port Lincoln in Australia show sea levels falling in the last decade.

  39. phlogiston says:

    knots340 says:
    May 16, 2012 at 6:02 am
    Why is no one doing the obvious? The data is in the form of sea level vs time, so take the derivative which gives the velocity in mm/year; which is the slope of the trend line. Next take the second derivative which will give the acceleration. What is that value? I would guess, given an almost perfect straight line fit to the data, that the acceleration is very close to zero.

    The derivative i.e. change of seal level in mm/year is given at Climate4you.

    Go to the ocean page and scroll to near the bottom. The rate of change mm/yr has been falling for 15 years and for most of the last year was below zero.

  40. Brad says:

    They can more easily cook the books using satellites, thus LET THE REAL DATA DIE and let the models and the manipulation live!

  41. Ian-Uk said

    ‘In a debate in the UK parliament last night, the leader of the Green Party stated that the British government is planning to upgrade the Thames Barrier to cope with a projected (IPCC, of course) sea level rise of 1.9m.’

    It is complete nonsense of course. Here is a BBC report that almost gets to the heart of the matter

    http://news.bbc.co.uk/1/hi/5092218.stm

    John Prescott deemed that London would get tens of thousands of houses in the Thames Gateway. The EA refuse to allow developers to breach national flooding guidelines by building on sites without protection and developers dont want to build without some guarantee that the houses they build won’t flood and purchasers will be able to get insurance. There is no such IPCC projection as 1.9m in any accepted timescale such as 2100 and around 30cm seems more likely which includes land sinking and a continuation of the very modest sea level rise over the last century.

    The green party have scare mongering form on this, but are right inside the govt environment committees and make outlandish claims that few dare to question.

    I asked Caroline Lucas what temperature reduction would be achieved if their harsh policy of co2 reduction was implemented-after much deliberation they refused to tell me. (the answer is so embarassingly small they wouldn’t want to let their troops know).

    tonyb

  42. M Courtney says:

    May 16, 2012 at 3:47 am
    “Bloke down the pub says:
    May 16, 2012 at 2:32 am
    You ask about Newlyn’s accelerating sea level rise. Just a thought but the National Trust has started (about 2008) to concrete in the causeway to St Michael’s Mount (just around the bay)’

    —– ——-

    In my article here I wrote about changes in sea level in a historic context from the Holocene to the Romans..

    http://judithcurry.com/2011/07/12/historic-variations-in-sea-levels-part-1-from-the-holocene-to-romans/

    A couple of paragraphs in you will see a reference to a ‘longer document.’ This will take you to the full article which carries out an extensive study on the sea levels around St Michaels Mount. Current Levels appear to be slightly lower than those experienced by the Romans when they used the harbour for collecting tin.
    tonyb

  43. Watchman says:

    This is not a hemispheric distribution of sites, but rather almost entirely four distinct clusters – Calfornia coast (one small area of eastern edge of the Pacific), Florida (which at least covers two seas), two very close readings in Brest and Newlyn (Britanny and Cornwall are parallel peninsulas – so the divergence in results needs explanation there) and a cluster in the mediterranean. Nothing in the Indian or Artic oceans, or on the western edge of the Pacific. Only one observation not on a continental shelf as well – which might be significant. If this is the information we have to go on, I would be reluctant to base anything on it.

  44. The sites lost from Douglas include 3 in New Zealand (quite a cluster!) and 2 in Panama and 1 on a volcanic island (Tenerife). These I would deem unacceptable from a tectonic point of view. Are you measuring sea level change or change in the rise of the ground (distance to the center of the earth) from tectonic forces and magma displacement? So, no loss there.

    Let’s look at the stations that are used:
    Hawaii – Volcanic Island
    San Diego, Santa Monica, San Francisco, La Jolla – a stones throw from a major tectonic plate boundary with movement of 50 mm per year!
    3 in Florida – a suspicious cluster that I would rather treat as one location with three redundant readings. If Florida moves, they all move.
    Trieste Italy – another plate boundary, micro plate to be sure, but Italy sticks above the water for a reason.

    I think a separate study needs to be done using tide gauges anchored into granitic plutons and measure sea level, glacial rebound and all. Favor the passive margins of continents.

  45. Hector M. says:

    About the dropped Argentine sites: Quequen is indeed a seaside location, but Buenos Aires is at the upper part of the River Plate freshwater estuary, and could not possibly be used to gauge sea level, I guess.

  46. alcheson says:

    Excellent article. TIde gauges are the way to go for monitoring sea levels. After all, what is really important is the relative change of sea level with respect to land. Forget the rebound correction used by the warmists, that is stuipid for determining if a city or shoreline is going to be submerged under water. Satellite data may be interesting but not is better than monitoring sea level were it actually counts – on the ground right at the waters edge.
    Satellite data is too easily corrupted by personal biases since numerous “corrections’ have to be made to the data. Following tide gauges also lets you monitor individual locations, some could be going up and some down, allowing you to determine if a particular location has a potential problem that has nothing to do with the overall sea level change.

  47. Seems like you missed out finding recent data. For a start have a look that the paper by P J Watson “Is There Evidence Yet of Acceleration in Mean Sea Level Rise around Mainland Australia?” Journal of Coastal Research Mar 2011. For Fremantle in WA records go back to 1897. Sydney Habour (Fort Denison) goes back to 1914. There is a paper “The Sea Level at Port Arthur, Tasmania, from 1841 to the Present” by Hunter et al in Geophysical Research Letters

  48. Richard "BAJA" Bell says:

    Like many thousands of the worlds population who go down to enjoy the sea, I have been walking on the same beach on the south coast of the UK for over 50 years. NOTHING HAS CHANGED and I do not expect it too. Could any sane person really notice any kind of rise measured in a fraction of an inch ( or euro mm ! ) .

    Just like a tiny temperature rise over a time period IT IS IRRELEVANT ………most people go on holiday to a hot country for the specific purpose of being in a warmer climate than they usually live ……… in a lot of cases this will be on a beach somewhere in the world, which most likely has not changed either !!!

    Paraphrasing my favorite weather guru ENJOYS THE SEA IT THE ONLY SEA YOU’VE GOT

  49. Sorry the above was posted before I finished. The latter paper is GPRL no7 2003. but you should able to find more recent information on the BOM web site. The sea level rise at Port Arthur from 1841 averages 0.8mm/yr. A similar rise is presently occuring on the East Coast of the Australian mainland Port Kembla, Sydney, Newcastle, Brisbane and Bundaberg which all have records of over 60 years.

  50. We are all aware of the diurnal Oceanic Tides. And we should be always keep in mind that when we speak of a 1.8 mm/yr or better 180 mm/century trend, it needs to be compared with a 1000 mm (Tuvalu) -10000 mm (Anchorage, AK) daily tidal amplitude.

    But there is also the lesser know, Earth Tide where the Moon deformes the Earth’s Mantle and crust by as much as 384 mm — twice a day. So, there is no tidal gauge that is at a constant elevation. Just another complication. ;-)
    “Eppur si muove”

  51. Urederra says:

    Tenerife is not a Country neither a State, It is an island. Last line should read Santa Cruz de Tenerife Spain.

    Just being picky.

  52. Keith Battye says:

    This one simple analysis shoots the CO2 driven AGW narrative in the head. CO2 rises over the entire period and we are told that this causes the Earth to warm , catastrophically, yet if this were the case the signal would show as accelerating sea level rise.

    No acceleration , no link to CO2. Perhaps we are being lied to over the “rising global temperature ” too. Perhaps we are being lied to over the anthropogenic component of CO2 in the atmosphere. This nonsense has gone on for too long now and it has ceased to be amusing.

  53. Kasuha says:

    I welcome this as a nice and solid analysis of changes in sea level rise rate. Thank you very much for your hard work.
    I’d only suggest to completely avoid discussion about true sea level change rates as without compensating for isostatic rebound you can’t get any realistic values. Yes I agree isostatic rebound itself is black magic but it’s part of what’s really happening.

  54. Phil. says:

    Ian_UK says:
    May 16, 2012 at 5:23 am
    In a debate in the UK parliament last night, the leader of the Green Party stated that the British government is planning to upgrade the Thames Barrier to cope with a projected (IPCC, of course) sea level rise of 1.9m. The above report (and similar studies) suggest this would be a waste of money. I’ve written to my MP asking if the story’s true, if so, how much it will cost and what due diligence the government has carried out to justify the expense. I don’t expect to get a sensible answer, though.

    Well you should take a look at the statistics on how frequently the barrage has had to be deployed over the years, definitely increasing.
    In the 1980s there were four closures, 35 closures in the 1990s, and 75 closures in the first decade of this century.

  55. jayhd says:

    I’ve boated on the Chesapeake Bay and the Atlantic Ocean for over fifty years. Someone please explain to me how normal tides, storm tides, waves (of all kinds) and all the other various naturally occurring phenomena that cause the depth of the water under my keel to increase or decrease on a regular basis are factored out when someone is trying to calculate an overall increase or decrease in sea level?

    Jay Davis

  56. Paul S says:

    Paul Homeward

    The aim was to replicate Bruce Douglas’s study, not to create a new global assessment.

    The title of the post is ‘Is sea level rise accelerating?’. Conclusion possibility (1) above is ‘The original Douglas study is based on an unrepresentative sample or inaccurate records.’ I’m pointing out that this is clearly the case: the sample (at least the cut-down one presented here) is highly unrepresentative.

    Incidentally sea levels at Port Adelaide and Port Lincoln in Australia show sea levels falling in the last decade.

    I’ve downloaded both of these. The 2001 to 2010 trend at Port Adelaide is ~5mm/yr and at Port Lincoln is ~2.5mm/yr. The best case for your contention is found by starting at 2000, a local maximum: Port Adelaide produces 2mm/yr, Port Lincoln is flat. That does lead me to another point: these tide gauge records provide a measure of coastal sea level change, which is not necessarily representative of the global mean at decadal timescales. Figure 2 from Prandi 2009 shows that a flat coastal trend from 2000 to 2007 is actually consistent with a ~3mm/yr global trend.

  57. agfosterjr says:

    Jens Bagh says:
    May 16, 2012 at 1:03 am
    Were sea levels to be rising this would slow down the rotation of the earth. Has any change been noted in the rate of change of rotation and if so how does this compare to the present study?
    =============================================================================
    Oddly enough, LOD responds to sea level rise differently depending on whether the source is thermal expansion or melting ice. Of course thermal expansion adds no mass, but it does move it further from the center of gravity so that it flows toward expanding shallow coasts. It just so happens that shallow coasts are concentrated nearer to the poles than would be expected at random, much reducing the rate at which thermal expansion increases LOD or even reversing it, whereas rise due to melted ice should increase LOD by about .1ms per cm. So to determine the overall effect we have to know what fraction of rise is due to which source, when in fact the rise is so miniscule that neither satellites nor gauges can measure the combined effect accurately.

    Still, LOD places limits on possible ice mass transfer, but core/mantle coupling is suspected of having a greater decadal effect on earth rotation. The earth’s loss of angular momentum can be calculated by measuring the rate of lunar recession. Secular deceleration of earth rotation can be calculated from ancient astronimical observations. The former gives a rate of 2.3ms/century and the latter yields 1.7. The difference is attributed to isostatic adjustment. The past couple of years have seen LOD hang around 1ms over the 1800 standard, meaning .5ms/century, a third of the normal. And since the advent of the atomic clock LOD has hardly increased at all, though it fluctuates on a number of time scales.

    The core/mantle excuse is only good up to a point–time wise and amplitude wise: catastrophic sea level rise would certainly increase LOD to an easily measured rate, and this is not happening. J2 –a measure of earth curvature–can theoretically distinguish between core angular momentum contribution and sea level contribution to LOD, hence between thermal and mass expansion of the sea, but as with temperature and tide gauge measurements, noise predominates.

    I might add that the LIA and MWP can be roughly inferred from reconstructed LOD. –AGF

  58. Jim G says:

    mikelorrey says:
    May 16, 2012 at 12:18 am
    “It should be obvious that if the southern hemisphere has zero sea level change, and all the sea level change is in the northern hemisphere, that that change is all due to post-ice-age rebound issues, period.”

    Agree, not to mention where does the water in the bowl go if any part of the bottom rebounds upward? I grew up in an area which had minor quakes due to rebound and they were interesting to say the least.

  59. DR says:

    Pictures. Where are the pictures? There should be thousands upon thousands of examples of sea levels encroaching on docks, moors etc. over the past 100 years. Where are they?

  60. Paul S says:

    mikelorrey says:
    May 16, 2012 at 12:18 am
    “It should be obvious that if the southern hemisphere has zero sea level change, and all the sea level change is in the northern hemisphere, that that change is all due to post-ice-age rebound issues, period.”

    AVISO provide a tool, with which you can isolate hemispheric sea level rise. The Southern Hemisphere trend from 1993 is about 3.25mm/yr, Northern Hemisphere is 2.17mm/yr. These plots are produced without GIA correction, I would think the hemispheres are more even after taking that into account.

  61. Ian says:

    The question, ultimately, is whether there is a detectable increase in the rate of sea level rise, which needs to occur if the dire predictions of Messrs Hansen et al. are to be realized. There does not seem to be convincing evidence that such acceleration is occurring, despite the claims of accelerating “climate change” over the last half of the 20th C. Interesting abstract of a 2011 paper on the situation around the US, from the Journal of Coastal Research. The authors appear to have determined that the rate of sea level rise is decelerating around the US. They also extended the 1992 Douglass study, and a study by Church & White (2007), and find similar evidence for a small deceleration of the rate of sea level rise.

    J. R. Houston and R. G. Dean (2011) “Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses”. Journal of Coastal Research: Volume 27, Issue 3: pp. 409 – 417.

    Abstract:

    Without sea-level acceleration, the 20th-century sea-level trend of 1.7 mm/y would produce a rise of only approximately 0.15 m from 2010 to 2100; therefore, sea-level acceleration is a critical component of projected sea-level rise. To determine this acceleration, we analyze monthly-averaged records for 57 U.S. tide gauges in the Permanent Service for Mean Sea Level (PSMSL) data base that have lengths of 60–156 years. Least-squares quadratic analysis of each of the 57 records are performed to quantify accelerations, and 25 gauge records having data spanning from 1930 to 2010 are analyzed. In both cases we obtain small average sea-level decelerations. To compare these results with worldwide data, we extend the analysis of Douglas (1992) by an additional 25 years and analyze revised data of Church and White (2006) from 1930 to 2007 and also obtain small sea-level decelerations similar to those we obtain from U.S. gauge records.

  62. Ian says:

    Oops..Church & White is 2006.

  63. @ Stephen Rasey

    I think a separate study needs to be done using tide gauges anchored into granitic plutons and measure sea level, glacial rebound and all. Favor the passive margins of continents.

    The stations were selected by Douglas originally. It would be nice to select many more to give a wider coverage, but according to Douglas, no others gave long enough records or matched his other criteria.

  64. Not exactly pictures of docks being flooded, but here is a map of New Orleans subsidence rates.
    Anything on the yellow-red side of the scale is subsiding at greater than 5.5 mm/yr, with the airport in the 10-20 mm/yr range. (average of years 2002-2005)
    http://earthobservatory.nasa.gov/IOTD/view.php?id=6623

    FYI, New Orleans sits atop 40,000 feet of Mississippi River Delta sediment that has been slowly dewatering and compacting since the Jurassic – about 100 million years.

  65. @ Hector M

    Buenos Aires is at the upper part of the River Plate freshwater estuary, and could not possibly be used to gauge sea level, I guess.

    Apparently the gauge is smack bang in Buenos Aires and ran from 1905-1987.

    http://www.psmsl.org/data/obtaining/stations/157.php

  66. @Kasuha

    I’d only suggest to completely avoid discussion about true sea level change rates as without compensating for isostatic rebound you can’t get any realistic values.

    Thanks. According to Bruce Douglas the isostatic adjustments were “typically ~3cm/ century”, and of course could go either way.

  67. agfosterjr says:

    I should have made it clear that the 1.7ms/century deceleration is attibuted to tidal friction, not sea level rise, so that LOD increase since 1800 is 1ms less than normal. If it is wrong to attribute this to CAM then it would suggest ice growth at the poles. And half the time CAM causes a decrease in LOD–it is only assumed that at present it increases it, though magnetic field studies are invoked to buttress the CAM argument. –AGF

  68. @ Paul S

    I’m pointing out that this is clearly the case: the sample (at least the cut-down one presented here) is highly unrepresentative.</i.

    Which raises the question, was it ever representative? Was sea level really increasing during the 20thC at 1.8mm/yr?

  69. agfosterjr says:

    Total rewrite: I should have made it clear that the 2.3ms/century deceleration is attributed to tidal friction, not sea level rise, leaving the 1ms departure from normal 1.7ms since 1800 to be explained. If it is wrong to attribute this to CAM then it would suggest ice growth at the poles. And half the time CAM causes a decrease in LOD–it is only assumed that at present it increases it, though magnetic field studies are invoked to buttress the CAM argument. –AGF

  70. Ian says:

    Houston & Dean then exchanged replies with everyone’s favourite – Stefan Rahmstorf (it would be interesting to read the article and then subsequent exchanges: pity it’s all paywalled):

    Stefan Rahmstorf and Martin 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(3), 409–417. Journal of Coastal Research: Volume 27, Issue 4: pp. 784 – 787.

    J. R. Houston and R. G. Dean (2011) Reply to: Rahmstorf, S. and Vermeer, M., 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(3), 409–417. Journal of Coastal Research: Volume 27, Issue 4: pp. 788 – 790.

    On sea rise in Australia, there’s a 2011 article from PJ Watson. He finds no substantive evidence of any increasing rate of sea level rise around Oz.

    P. J. Watson (2011) Is There Evidence Yet of Acceleration in Mean Sea Level Rise around Mainland Australia?. Journal of Coastal Research: Volume 27, Issue 2: pp. 368 – 377.

    Abstract.

    As an island nation with some 85% of the population residing within 50 km of the coast, Australia faces significant threats into the future from sea level rise. Further, with over 710,000 addresses within 3 km of the coast and below 6-m elevation, the implication of a projected global rise in mean sea level of up to 100 cm over the 21st century will have profound economic, social, environmental, and planning consequences. In this context, it is becoming increasingly important to monitor trends emerging from local (regional) records to augment global average measurements and future projections. The Australasian region has four very long, continuous tide gauge records, at Fremantle (1897), Auckland (1903), Fort Denison (1914), and Newcastle (1925), which are invaluable for considering whether there is evidence that the rise in mean sea level is accelerating over the longer term at these locations in line with various global average sea level time-series reconstructions. These long records have been converted to relative 20-year moving average water level time series and fitted to second-order polynomial functions to consider trends of acceleration in mean sea level over time. The analysis reveals a consistent trend of weak deceleration at each of these gauge sites throughout Australasia over the period from 1940 to 2000. Short period trends of acceleration in mean sea level after 1990 are evident at each site, although these are not abnormal or higher than other short-term rates measured throughout the historical record.

  71. Re: Phil @ 8:42 am – In the 1980s there were four closures, 35 closures in the 1990s, and 75 closures in the first decade of this century.

    From: Sea level – The Thames Barrier Statistics, (2003)
    http://www.ff.org/centers/csspp/pdf/16-CSPP-thamesbarrier.pdf

    It is true that the Thames Barrier has been closing with increased frequency;
    however, the reasons behind this have little to do with global climate change.
    According England’s Centre for Ecology and Hydrology (from a report
    developed in cooperation with England’s Department for Food, Environment
    and Rural Affairs):
    “Historical records of rising tide levels in London reflect the fact that SE England
    is tilting downwards at around 30 cm a century, and that settlements have
    narrowed the river – the width of the Thames at Westminster is now about
    one-third of its width in Roman times.”
    “Because the Thames River Barrier is now subject to different operating
    rules, it may be less useful as an indicator. The barrier is now closed to retain
    water in the Thames River
    as well as to lessen the risk of flooding. (It was
    closed on 9 successive tides at the start of 2003.) Thus, the number of closures
    has increased greatly in recent years. This indicator would only be useful if it
    were possible to distinguish the number of closures made specifically to lessen
    flood risk.”
    … but since the river channel has been greatly modified and since the region
    has been sinking due to development and other geological influences,
    even a true indicator of flooding potential would not clearly reflect the influence
    of climate changes. Thus, the use of the Thames Barrier statistics by Mr. King
    to demonstrate climate change is not a fair use of the data.

    ref: Indicators of Climate Change in the U.K., 2003. Centre for Ecology and
    Hydrology. (http://www.nbu.ac.uk/iccuk/)

  72. agfosterjr says:

    It’s worse than we thought, but I hate to leave mistakes:
    LOD should have increased by 2 x 1.7ms = 3.4ms since 1800, but has only increased by 1ms, leaving 2.4ms or 1.2ms/century to be explained. Maybe CAM, maybe not. –AGF

  73. @ Homewood 10:36: It would be nice to select many more to give a wider coverage, but according to Douglas, no others gave long enough records or matched his other criteria.

    I believe the too many stations Douglas chose fail a tectonic setting test. Long records are probably to be had from China, Japan, Hong Kong, India, Persian Gulf, Scandinavia, Gibralta, Lagos and Luanda. New York, Boston, and the sea faring town of New England probably have long records, too. Gather them all. Group them by tectonic setting. Let the data speak for themselves. Don’t cherry pick the locations by some isostatic rebound criteria.

  74. AnonyMoose says:

    If you’re wondering if removing the Southern Hemisphere stations might affect the rate, simply get the data from the obsolete stations and calculate the rate for those. If their rate is the same as the global, then their data in the original study did not affect the global rate of the original study. It’s too bad that we can’t see their current data, but at least you can check what their rate used to be.

  75. David Porter says:

    How can it be rising? The level, according to Josh, still only comes half way up a duck.

  76. Bill Parsons says:

    Gasp! 20 Cm? In only 130 years?

    Quick. EVERYBODY! Don’t stop to think. Run the other way. High ground is this way… Er, no, this way… oh Woe is us!

    Now I understand Al Gore’s reticence about beach-front property… er, wait.

  77. @ Stephen Rasey

    I believe the too many stations Douglas chose fail a tectonic setting test. Long records are probably to be had from China, Japan, Hong Kong, India, Persian Gulf, Scandinavia, Gibralta, Lagos and Luanda. New York, Boston, and the sea faring town of New England probably have long records, too. Gather them all. Group them by tectonic setting. Let the data speak for themselves. Don’t cherry pick the locations by some isostatic rebound criteria.

    I presume Douglas had good reasons to pick the stations he did and leave out the ones you suggest.

  78. Mark Bofill says:

    Honestly don’t undestand this, anyone give me the basic idea why the satellite measurements are so substantially different from the tide gauges? I had somebody argue with me not long ago that sea level rise ‘accelerated’ because the older tide gauge data showed a smaller increase than the satellite data does now. This article suggests I was right to doubt this claim, but I still can’t explain the satellite / tide gauge discrepancy because I don’t understand it at all. Heelp?

  79. agfosterjr says:

    To put the rate of sea level rise in perspective, the Atlantic Ocean is widening at 10 times the rate of sea rise. Dust and landfill accumulate faster. Tells–ancient city mounds made of dust and debris–grew faster than the sea rises. And as we know, coral has grown fast enough to keep up with most or all past rates. Plenty of geological processes dwarf the rate of sea rise, making its modern measurement more theoretical than problematic. –AGF

  80. Dave Wendt says:

    In Appendix A sea level is given for each site for 2000 and 2011 with the values all being in the general vicinity of 7 meters +/-. My question is 7 meters relative to what exactly?

  81. Ian says:

    An interesting presentation on sea level rise and estimates of trends: http://publicwiki.deltares.nl/download/attachments/76616483/present.pdf

    Section 4 covers the problems of overestimating the trend in sea level rise – where forecasts do not match observations, but analysis exaggerates the trend. Problems identified included: sensitivity to starting period (so, cherry picking the start); sensitivity to the end period (cherry picking the end); use of the “nodal cycle” (starting at the bottom of a cycle, terminating at the top); improper calculation of trends; using trends obtained from different datasets to argue for an increase in rate of rise; application of “corrections”, etc.

    Certainly a fraught area of study: the problem is more complex and results are far less clear than those promoting alarm would care to admit. Gee, isn’t that unusual?

  82. JustSaying says:

    Paul S: The 2001 to 2010 trend at Port Adelaide is ~5mm/yr and at Port Lincoln is ~2.5mm/yr. but…. The historic tide gauge records from Port Adelaide and Outer Harbour are one of the more important datasets from the Australian region purporting to show a significant rate of local sea level rise. However, geological evidence including radiocarbon dated palaeosea level indicators, indicates that most of this rise is due to subsidence of the land. The subsidence is significant but localized, and can be largely attributed to human activities associated with port development, reclamation and industrialization….

    The tide gauge data from Port Adelaide and Outer Harbour have been used in global sea level rise calculations without adequate local neotectonic correction. Although outside the zone of greatest land subsidence, three‐quarters of the secular rise in mean sea level of 2.5–2.9 mm/year indicated by the tide gauge records can be attributed to land level changes. Hence the local sea level trend is a rise of 0.7 mm/year.
    From A. P. Belperio “Land subsidence and sea level rise in the Port Adelaide estuary: Implications for monitoring the greenhouse effect”, Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia
    Volume 40, Issue 4, 1993 [OK so it's quite old :-)] pp 359-368

  83. pk says:

    this business of measuring sea level is a hundred times worse than herding ten thousand cats with two dogs.

    firstly i worked for thirty plus years at a shipyard on the west coast. my desk was about 100 feet from the waters edge. it was, depending on the tide anywhere from six to fifteen feet below sealevel.

    secondly there is this matter of measurement. if you take ten sheets of standard copy machine paper then their thickness is approximately 1 MM. or .039″. for the folks that like to throw that figure around remember that machinests work to .0005″ all day every day and some work to .0001″ (the limit where thermal expansion can be detected on the shop floor) as a normal thing. the engraved lines on insturments are about .006″ wide and most individuals with a little training can “split the line”.

    if you are trying to measure sea level in a station in a harbor then have you considered the following variables. tides, in southern california in a south facing harbor, the tidal variation between spring extreme high tide and spring extreme low tide can be as much as 12 feet (and it happens in a matter of about 12 hours). then there is the business of temperature. the railroad people who have literally miles of steel rail to measure consider that the coeficient of expansion of steel is .0001″ per inch per degree farenheight change in temperature. so for the soul that wants to hang a tidal guage from the golden gate bridge, just when do you take the measurement . the bridge is probably about 3/16″ (.187″) taller in the afternoon than it was in the morning. (you can’t say we will do it at 1200 local time because the high tide low tide cycle works on about a 11.5 hour period.) besides if you would care to walk across a really large bridge you would find that out in the middle they bounce up and down quite a bit naturally [getting stopped out in the middle of a suspension bridge during a traffic jam at rush hour can be quite scary what with the swaying, and bouncing that they do.]
    then there is that thing that all harbors have called “surge”. in the los angles/long beach harbor it is a very long period “wave” that takes about 15 minutes to happen. in simplification it is a change in the local appearent sealevel that changes with weather, temperature, large ships going by, small ships going by, tugboats with fuel barges manuevering…….. of course the occasional tsunami contributes……. even a rowboat twenty feet from the guage can affect the readings. then we have the chop. what effect does chop have on the sealevel guage. i know that they are hidden in vertical pipes at the waters edge (used to do a bit of fishing beside one) with inlet holes down pretty deep. but do the lads ever consider that the wind that blows chop toward the gauge also moves water towards it and vice versa therby giving a false reading………………..

    i guess that what i’m leading up to is that there are so many variables in measuring ocean levels that the authority on this must be a world class statistician who grew up in huntington beach ca and is working at either a major estuary or harbor having gotten his/her degree at Pepperdine. (its within sight of the Pacific Ocean).

    remember, its the dumb little things that will mess you up.

    C

  84. Billy Liar says:

    notalotofpeopleknowthat tidal observations are corrected for the ‘inverse barometer’ – a 1mb (0.03″Hg) increase in local atmospheric pressure will depress your local sea level by very close to 1cm (0.4″). A low pressure system over your locality at 975mb (28.79″Hg) will increase your local sea level by ~15 inches. Kinda puts the annual mm level changes into perspective.

    Stephen Rasey says:
    May 16, 2012 at 7:06 am

    I think a separate study needs to be done using tide gauges anchored into granitic plutons and measure sea level, glacial rebound and all. Favor the passive margins of continents.

    John Daly (“Still Waiting for Greenhouse) thought that Australia was tectonically stable and much less affected by PGR than either Europe, Asia or North America. He has a table on this page:

    http://www.john-daly.com/ges/msl-rept.htm

    showing that:

    Eleven of the 27 stations [in the National Tide Facility Survey 1998] recorded a sea level fall, while the mean rate of sea level rise for all the stations combined is only +0.3 mm/yr, with an average record length of 36.4 years. This is only one sixth of the IPCC figure. There was also no obvious geographical pattern of falls versus rises as both were distributed along all parts of the coast.

    But there’s more. It was shown earlier that Adelaide was a prime example of local sea level rise due to urban subsidence. It’s two stations in the above list are the only ones to record a sea level rise greater than the IPCC estimate. The same NTF survey pointed out the Adelaide anomaly and directly attributed it to local subsidence, not sea level rise, on the grounds that the neighboring stations of Port Lincoln, Port Pirie and Victor Harbour only show a rise of +0.3 mm/yr between them. If we exclude Adelaide from the list, the average sea level rise for the other 25 stations is then only +0.16 mm/yr, or less than one tenth of the IPCC estimate.

  85. Mark from Los Alamos says:

    Very nice! This just might be the most useful data for understanding global warming that exists.

    Once corrections are made for isostatic rebound and land subsidence, the multi-year average rate of sea level rise is a direct measure of the warming rate – more warming of the ocean means more thermal expansion of the water and more warming also increases the ocean volume through melting of continental ice masses. What this data says is that the ocean (and glaciated land mass) was warming just as fast from 1900 to 1910 as it warmed from 2000 to 2010. Since the sea-level rise has been ruler-straight for the last 100 years, and since CO2 concentrations were far lower in 1900 than 2000, one can conclude that CO2 isn’t the dominant factor in creating the heat balance disequilibrium that has existed for the last 100 years.

  86. Latitude says:

    Mark Bofill says:
    May 16, 2012 at 12:25 pm

    Honestly don’t undestand this, anyone give me the basic idea why the satellite measurements are so substantially different from the tide gauges?
    ==========================
    Because, since satellites fall out of orbit….and get closer to the earth……satellite measurements are adjusted up……just like UHI

  87. For the record, the tidal gauges for the two Australian sites read :-

    Port Adelaide – 1966 – 6875mm
    2000 – 7021mm
    2010 – 6988mm

    Port Lincoln – 1966 – 6897mm
    2000 – 7034mm
    2010 – 6975mm

  88. agfosterjr says:

    pk says:
    May 16, 2012 at 1:54 pm
    =============================================================================Very interesting. Still, your desk was below sea level; apparently the pumps never gave out. And the complications you describe remain miniscule compared to the problems with measuring global T, and could be more easliy overcome.

    As for the wakes of boats, here’s something you might find interesting–I read in an old book about sea level on Lake Geneva that reported consistent changes measured right when the steamers entered or left harbor–on the opposite shore! While initially we conceive of boat propulsion as resulting from propeller thrust, the fact remains that the prop current can only push water against water, which must ultimately result either in a circumpolar current or in a transfer of energy to the lithosphere. Such a transfer is effected by a small rise in sea level on the shore. Similarly the lift of a plane is accomplished by increasing the air pressure beneath and behind it. The point being, the wake of a boat is in fact higher than the surrounding water.
    Cheers, –AGF

  89. mbur says:

    Erosion?……………………………………….!.WUWT.
    Thanks for all the interesting articles and comments.

  90. Olle Lundblad says:

    Mark from Los alamos.Your remark is quite convincing,but there is one more point to discuss:According to IPCC (AR4.5) sea level increase is depending on two factors Ocean temp
    and ice melting ,about half for each factor.If ocean temperature and ice melt can be presumed
    varying together,then they must have been nearly constant all the time since 1880.Means the ocean temperature has not increased at all.Where is the CO2?

  91. pk says:

    @agfosterjr:
    its a pretty common thing to be fishing on a quay wall and see small waves breaking on the wall and the only reasonable explanation was a ulcc going by a mile away and thirty minutes past.

    what i was trying to illustrate is that there are so many variables in this matter that its not particularly bright to make hard rock claims of sub millimeter activity or movement.

    the reason for my desk being below sealevel was that a benchmark that was surveyed monthly and established in 1943 had dropped 23 feet by 1953 and then re risen by about 15 feet by 1968.

    the cause of sinkage was attributed to subsidence caused by oil “recovery” activities. the rerise was attributed to steam injection to enhance that recovery.

    C

  92. Tom Harley says:

    Broome in the NWest of Australia had the main town centre built at the high tide mark before 1900, for the Pearling Induistry, and is still there, at the same high tide mark in 2012.

  93. spangled drongo says:

    Can satellites ever correctly measure MSL?

    http://www.esri.com/news/arcuser/0703/geoid1of3.html

  94. Philip Bradley says:

    jh says:
    May 16, 2012 at 2:08 am
    Point of information.
    How does the eruption of a volcano affect measured rise in sea level?

    The aerosols released affect the amount of water vapour in the atmosphere, and hence the amount of water in the oceans.

    As the study I quoted above shows, the effect is large, several times larger than the ‘normal’ annual rate of sea level rise and continues over several years.

    Which suggests that a component of sea level rise may result from reductions in anthropogenic aerosols (overwhelmingly in the NH) and may partially explain the NH – SH sea level change differences.

  95. jpenhall says:

    All the evidence in fact shows that contrary to the IPCC’s claims, sea-level rise is not accelerating. UK oceanographer Simon Holgate (2008) analysed nine long sea-level records for the period 1904-2003. He found that between 1904 and 1953, sea-level rise was 2.03 mm per year, compared with 1.45 mm per year for the period 1953-2003.

    Further proof that sea-level rises are not increasing, as the climate models predict, comes from a paper by Phillip Watson (2011). Based on century-long tide gauge records from Fremantle, Western Australia (1897 to present); Auckland Harbour in New Zealand (1903 to present); Fort Denison in Sydney Harbour (1914-present); and Pilot Station at Newcastle (1925 to present), Watson concluded there was a consistent trend of weak deceleration from 1940 to 2000. Climate change researcher Howard Brady of Macquarie University was quoted in The Australian of Friday 22 July 2011, p. 1, as saying that the recent research meant sea level rises accepted by CSIRO were already dead in the water as having no sound basis in probability. He added that divergence between sea-level trends from climate models and sea-level change from the tide-gauge records was now so great that it was clear there is a serious problem with the model.
    For further evidence that the IPCC’s case is a massive fraud, please go to my website:
    http://jpenhall.wordpress.com/2011/04/02/why-i-remain-a-climate-sceptic-in-relation-to-human-emissions-of-co2/
    John Penhallurick

  96. E.M.Smith says:

    In all these studies of sea level rise, there is talk of warming water and talk of isostatic rebound, but precious little about sediment filling in the oceans.

    The entire Grand Canyon washed down the Colorado river and filled in a large chunk of the Gulf of California. That has to count for something. How about all the other tons of sediment per day washing down the global rivers?

    http://chiefio.wordpress.com/2011/04/01/where-did-the-grand-canyon-go/

    Then there is all the volcanic “stuff” from all the ocean floor volcanoes and rifts. Just ignored?

    Frankly, the floor of the ocean is relatively thin and under strong compression from the spreading zones in the middle. Think maybe something 10 miles thick and 1000+ miles long can ‘buckle’ a bit some times? Up and down? We ASSUME the ocean floor is static when we know it isn’t static. That, IMHO, is a problem…

  97. Andrew says:

    Excellent post, Paul. Very clear, well-written and informative. I particularly liked the table showing how start year effects the 2011 result, and your expose of Church & White’s post-normal science approach to the analysis. Many thanks.

  98. tallbloke says:

    agfosterjr says:
    May 16, 2012 at 9:06 am
    Oddly enough, LOD responds to sea level rise differently depending on whether the source is thermal expansion or melting ice. …

    I might add that the LIA and MWP can be roughly inferred from reconstructed LOD. –AGF

    Thanks for the interesting comment. I’ve reposted it for discussion.
    Please link the LOD reconstruction you refer to.
    http://tallbloke.wordpress.com/2012/05/17/a-g-foster-jr-lod-and-sea-level/

  99. Keith Battye says:

    To say nothing of the variation in air pressure.

  100. Paul S says:

    Paul Homewood says:
    May 16, 2012 at 10:50 am

    Which raises the question, was it ever representative? Was sea level really increasing during the 20thC at 1.8mm/yr?

    The climatic influences on spatial sea level change patterns tend to somewhat even out over a centennial scale. You can see this effect in the Appendix A table above: the 2000-2011 trends range between -3.4 and +6.7, while the 1900-2000 trends have a much smaller range of 0.8 to 2.5. I think it may be possible that a hypothetical ensemble of 23 differently-situated suitable tide gauges might produce a significantly lower or higher trend over the 20th Century, but highly unlikely. Of course, the Douglass study is not the only one to look at this issue. There have been several papers (e.g. Holgate 2007, Jevrejeva 2008, Church & White 2011), each using different selection criteria and statistical techniques, and all arriving at estimates between 1.5 and 2mm/yr. This should really give us confidence that we know the “true” trend within a fairly tight range of uncertainty.

    Regarding the Port Adelaide and Lincoln data, as I pointed out earlier the 2000 datapoint represents a local maximum in these locations and indeed at a global coastal level. However, the linked Prandi 2009 paper demonstrates conclusively that a fairly flat coastal trend from a high point around 2000 is actually fully consistent with a 3mm/yr global trend (and Southern Hemisphere trend) when the open oceans are included.

  101. Canman says:

    Those 100 year sea level rise charts are the closest things that I see to a straight line in all of climate chartdom. About a foot a century.

  102. According to Prof. Nils Axel Morner sea levels have remained unchanged during to 20th century within fairly narrow margins that are certainly not as large as the figure quoted in your report.

  103. Thank you for a balanced and very well written article based on real and available data. I find it very convincing. You deserve a prize for this.

  104. Eric Adler says:

    Paul Homewood mentioned the Church and White 2011 paper, which looks at data since 1993 was influenced by a one time event, Pinatubo. This is a fair criticism. Church and White mention that in their abstract.

    http://www.springerlink.com/content/h2575k28311g5146/fulltext.html

    “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. ”

    One point not mentioned by Homewood is that Church and White say that their data shows that sea level rise has accelerated during the 20th century. They say in the abstract:

    “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”

    Why does Homewood fail to consider this point as worthy of discussion and instead focus exclusively on the Douglas paper, which has a much smaller data base which provides results that are less statistically significant.

    Also sea level rise in the Southern Hemisphere has been larger than the northern hemisphere. Ignoring the Southern Hemisphere also seems like a major flaw in the analysis.

  105. jayhd says:

    Again I ask. How are normal tides, abnormal tides and all the other naturally occurring phenomena that cause the sea level to rise and fall on a regular basis get factored out when calculating sea level change – especially when people are claiming changes in millimeters?

    Jay Davis

  106. ferd berple says:

    According to Wikipedia, Sea levels are at a historic low. Based on past evidence they have nowhere to go but up.

    http://en.wikipedia.org/wiki/File:Phanerozoic_Sea_Level.png

    Anyone wanting to confirm sea level rise only need consult the British Admiralty charts from 200-300 years ago. They are the most accurate record on earth to confirm any change. Yet they are ignored by researchers. Why? Because they show no appreciable change in sea level over the past 200-300 years.

    Thus, because these records show no change, researchers search all over the earth until they find proxies that show sea level change, and these are what they report. Researchers found long ago that o one pays for negative results. If you want future grants, you need to report only positive results.

  107. @ Eric Adler

    One point not mentioned by Homewood is that Church and White say that their data shows that sea level rise has accelerated during the 20th century. They say in the abstract:

    “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”

    The objective was to measure whether any acceleration had taken place since 1993.

    If you look at the Church & White graph, it is clear that the acceleration took place from about 1940 onwards, after a flat period in the early century. The real question is whether the aceleration has increased in the last 2 decades.

    http://www.springerlink.com/content/h2575k28311g5146/fulltext.html

  108. @ferd berple Re @ Phanerozic sea level low.

    Yes, but we are at a high-water mark within the last 20,000 years.
    http://commons.wikimedia.org/wiki/File:Post-Glacial_Sea_Level.png
    From Fleming 1998, 2000 and Milne 2005.
    A beautiful chart with t and z error bars.
    Total rise of >120 m of sea level since the glacial maximum.
    Oops! Keep everything in constant units for understanding…. make that
    Total rise of >120,000 mm of sea level rise in 10,000 years
    …(from 18 kyba to 8 kyba) (avg 12 mm/yr during the melt.)
    Uncertainty at any given station to be about 10,000 mm
    But total uncertainty across stations suffering different tectonic forces of >30,000 mm.

    A closeup of the past 7000 years:
    http://commons.wikimedia.org/wiki/File:Holocene_Sea_Level.png
    shows 4000 +/- 2000 mm rise in 7000 year (avg: 0.3 to 0.9 mm/yr)
    again you see a tectonic imprint on the locations of the data.
    Tahiti show evidence that it has tectonicly subsided by 10,000 mm in 7000 years, probably from cooling of the old magma chamber and general aging (thickening) of the oceanic crust causing isostatic depression.

  109. @Billy Liar,
    Sorry, when putting my list of alternate stations to use, I thought of Australia and neglected to included it before submittal. Also S. Africa. Australia is probably the most stable of all the tectonic plates that also has tidal records. By all means include them. How Douglas chose three in tectonically active New Zealand and skipped Australia is a tale that needs to be told.

    But to put it simply, I’d use every tidal gauge I could find in Australia as well as Florida, most of Africa (1), East China Sea, Vladivostok, Southern India, Eastern S. Am. I’d also include New York and New England and Baltic Sea ports since Brest and Newlyn were included and highlight all these as tectonically stable, but probable isostatic rebound stations.

    (1) Lagos is a failed triple point rift arm, but probably stable today, so I’d included it provisionally. I’d avoid NE Africa (Nile Delta, Red Sea rift) and Atlas Mtn NE Africa.
    Gobal Tectonic map:
    http://denali.gsfc.nasa.gov/research/lowman/Lowman_map1_lg.jpg

  110. Paul Vaughan says:

    agfosterjr (May 16, 2012 at 9:06 am) wrote:
    “LOD places limits on possible ice mass transfer, but core/mantle coupling is suspected of having a greater decadal effect on earth rotation.”

    That narrative has been eroded by climate …(& AGW-twisted too):

    Buis, A. (2011). NASA study goes to Earth’s core for climate insights.
    http://www.nasa.gov/topics/earth/features/earth20110309.html


    agfosterjr (May 16, 2012 at 10:52 am) wrote:
    “If it is wrong to attribute this to CAM then it would suggest ice growth at the poles.”

    Sounding more like Sidorenkov (2003 & 2005).

    …So a question that has been on my mind:
    How would that affect subcrustal flow topology and how would that affect the geomagnetic field?

    Sensible routes towards sound answers to such questions begin with very careful data exploration, not assumption-laden abstract theoretical fantasy.


    pk (May 16, 2012 at 1:54 pm) wrote:
    “the wind that blows chop toward the gauge also moves water towards it and vice versa therby giving a false reading……………….. “

    Someone with proper appreciation for wind. Bravo.

    http://i49.tinypic.com/219q848.png
    http://i40.tinypic.com/16a368w.png
    And p.4 here: http://wattsupwiththat.files.wordpress.com/2011/10/vaughn-sun-earth-moon-harmonies-beats-biases.pdf

    Solar cycle acceleration determines the variable lead of the solar-terrestrial thread [ http://upload.wikimedia.org/wikipedia/commons/0/00/Lead_and_pitch.png ]. (That’s simple “rise over run” grade 9 math for anyone who bothers to think for a second.) …But keep in mind that different terrestrial fields have different asymmetries. All have an annual cycle, but those annual cycles don’t all align (e.g. geomagnetic vs. climate equinoxes vs. solstices). The family of modulations demands more careful study. Agreement on disentanglement of parallel modulation &/or multi-directional coupling will hinge on more widespread lucid awareness of the nature of nonuniform multivariate moduli of spatiotemporal continuity. Based on instinct and quick visual inspection, it looks like (aside from unevenly-spaced data issues) it will be quite easy to tie multidecadal sea level acceleration to solar cycle acceleration via wind (when time & resources permit, as the months unfold).

    Regards.

  111. @Paul Homewood, I presume Douglas had good reasons to pick the stations he did and leave out the ones you suggest.

    Let’s look at criteria #2 again
    2.Not be located at collisional plate boundaries

    My objection is particularly in the use of 4 costal California stations, one in Italy, and possibly Marseilles. As for California, true, the San Andreas Fault is commonly referred as a strike-slip tectonic boundary, but that is only its primary component of its 50 mm/yr movement. The California Coastal Range owes its existence to that fault movement. It is compressional is some places, tensional in others, creating mini basins. These 4 stations make up one third of the database. Eliminating “collisional” plate boundaries is much too iffy a criteria. These 4 stations are simply too close to one of the most active plate boundaries in the world to anchor a global sea-level rise study.

    Trieste and Marseilles are associated with the mini plates of the Med. Some of the most active volcanos in the world are associated with plate movement that created Italy. Trieste is smack in the middle of a compressional zone between the Apennines and Dinaric_Alps and is at the foot of the Swiss Alps. I can’t imagine a much worse place to pick a tectonically stable tidal gauge. On the face of it, Trieste violates Douglas’s #2. http://scienceblogs.com/highlyallochthonous/2009/04/medtect.png Marseilles might be in a tensional zone, but it’s probably ok.

    Brest and Newlyn are only 200 km apart!
    New York and New England ports aren’t included because of Isostatic rebound, but Brest and Newlyn, further north than NYC, are?

    The clustering that is in this 12 point database and Douglas’s original 24 point database is eye-opening.

  112. Smokey says:

    Paul Vaughan says:

    “Agreement on disentanglement of parallel modulation &/or multi-directional coupling will hinge on more widespread lucid awareness of the nature of nonuniform multivariate moduli of spatiotemporal continuity.”

    Glad to see you’re back, Paul.☺

  113. agfosterjr says:

    Paul Vaughan says:
    May 17, 2012 at 12:40 pm
    ==========================================================================
    Can’t make heads or tails out of your solar weave. Would you mind explicating? –AGF

  114. agfosterjr says:

    jayhd says:
    May 17, 2012 at 7:07 am
    Again I ask. How are normal tides, abnormal tides and all the other naturally occurring phenomena that cause the sea level to rise and fall on a regular basis get factored out when calculating sea level change – especially when people are claiming changes in millimeters?

    Jay Davis
    ========================================================================
    By figuring the average. But yes, easier said than done. –AGF

  115. kim2ooo says:

    Mr Homewood:
    Clarification please.
    [" Of Douglas’s 23 sites, only 12 have full or nearly full records since. (Newlyn’s records go up to 2009, but are included). From these 12 stations, I have reconstructed the Douglas graph."]

    Included or excluded?

  116. pk says:

    Paul Vaughan:
    perhaps i should have shot my mouth off about hurricane surges also.
    aaaaah well.
    C

  117. Paul Vaughan says:

    agfosterjr (May 17, 2012 at 3:00 pm) wrote:
    “Can’t make heads or tails out of your solar weave. Would you mind explicating? –AGF”

    Before we start getting into the dozens of ways the robust pattern can be isolated:

    Do you understand Figure 3a & 3b (pdf p.24 & p.25) from the following article?

    Dickey, J.O.; & Keppenne, C.L. (1997). Interannual length-of-day variations and the ENSO phenomenon: insights via singular spectral analysis.
    http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/22759/1/97-1286.pdf

    Regards.

  118. Kim2000

    Yes, I have included Newlyn in the analysis.

  119. jayhd says:

    agfosterjr,
    By figuring the average – there’s the rub. Extraordinary events, such as Northeasters and hurricanes among other things, cause extraordinary surges that have nothing to do with sea level. These events really skew the results if we simply figure the averages. And the smaller the number of gauging stations used, the bigger the bias these one-off events introduce. Unless this issue is addressed adequately in the methodology used, any “average” computed is absolutely worthless. Especially if we are only talking about millimeters!

    Jay Davis

  120. agfosterjr says:

    jayhd says:
    May 18, 2012 at 6:30 am
    ===================================
    I don’t know how barometric pressure averages out at a given location. We know that sea currents have a significant long term effect, e.g., opposite sides of Panama. So does density (short term), allowing satellites to track T and haline variability. If low pressure surges have not been modeled out, then the record should show higher sea levels in hurricane years at any gauges affected only if high pressures don’t even out the record. The weight of the whole atmosphere is fairly constant.

    Polar air is denser–is the Arctic Ocean lower than a hypothetical geoid? Academic maybe–I doubt the difference could be measured, even if it were a foot–what with a pear shape and all. –AGF

  121. Billy Liar says:

    Stephen Rasey says:
    May 17, 2012 at 12:36 pm

    Many thanks for your reply.

    This is a fascinating topic! I have enjoyed reading your input and that of AGFoster Jnr too.

  122. agfosterjr says:

    Paul Vaughan says:
    May 17, 2012 at 10:52 pm
    ========================================
    At least there is text: “Fig. 3. The reconstructed LOD time series (in ms) obtained by combining the variance associated with two pairs of temporal principal components (T-PCs) (a) Annual
    component: Principal components (PCs): PCs 3 and 4; (b) Semi-annual components: PCs 5
    and 6.”

    But what I see is a couple of worn out screws with all useful data removed. And you provide no text to what appears at a glance to be useful data if any explanation were provided: x = day of year; y = year. I guess yellow is hot and torquoise is cold–increments unspecified. Is this global T? Semi-annual spectrum? Reminds me of Frost’s “Choose Something Like a Star.”
    –AGF

  123. As a counterpoint to the Douglas work, I have done some analysis on the Church & White study. They reckon their tidal gauge figures correlate pretty well with the satellite numbers, so it’s a useful paper.

    http://notalotofpeopleknowthat.wordpress.com/2012/05/18/sea-level-risea-look-at-church-white-2009/#more-1258

  124. Peridot says:

    Ian_UK says:

    May 16, 2012 at 5:23 am

    In a debate in the UK parliament last night, the leader of the Green Party stated that the British government is planning to upgrade the Thames Barrier to cope with a projected (IPCC, of course) sea level rise of 1.9m. The above report (and similar studies) suggest this would be a waste of money. I’ve written to my MP asking if the story’s true, if so, how much it will cost and what due diligence the government has carried out to justify the expense. I don’t expect to get a sensible answer, though.

    I was glad to read Stephen Rasey’s reply as I was beginning to think I was a lone voice about the Thames Barrier (NOT Flood Barrier). I use logic and a lot of reading to form an opinion. The fact the Barrier was build in entirely the wrong place for a flood barrier (way upriver at Shoreditch), the complete absence of ‘containment’ ( a massive job needing high embankments all the way to the coast of the estuary on both sides) and the complete absence of photos of the storm-surge water smashing into the closed barrier (very sexy confirmation of saving London from floods – how could have they forgotten to take them?). TheThames water-level in the ‘important’ parts of London, affected by over-extraction due to over-population in an area warmer and drier than anywhere else in Britain, frequently became low and unsightly. The Barrier was decided upon in the 70s during the Global Cooling scare. Rising sea-levels were not an issue.

    The last word I read about the new higher barrier was that after many years of chatter by the Environment Agency and assorted greens it had been shelved for 50 years. Is this being brought up again?

  125. Peridot

    For what it is worth, tidal gauges at Sheerness in the Thames Estuary show an increase since 1970 of 1.3mm/yr. (Isostatic changes account for about 0.7mm of this)

    More relevantly, we have never since had anything approaching the 1953 great flood which absolutely decimated huge tracts of land down the East coast and into the Low Countries, killing ten of thousands,.The Barrier of course would not have stopped this as it merely protected London.

    Indeed a similar occurrence would spell disaster for other areas as the Barrier would simply stack up water further down the estuary, where flood protection is no better than it was then.

  126. Paul Vaughan says:

    @agfosterjr (May 18, 2012 at 9:22 am)

    My impression from engaging in these online climate discussions is that many participants don’t have a knack for reproducing the graphs of others from scratch.

    I note your comments here…
    http://tallbloke.wordpress.com/2012/05/17/a-g-foster-jr-lod-and-sea-level/
    …asking about TB’s SSBz LOD T graph:
    http://tallbloke.files.wordpress.com/2009/11/ssb-z-lod-temp.jpg

    To reproduce:

    1. Go here:
    http://ssd.jpl.nasa.gov/horizons.cgi

    2. Set up:
    Ephemeris Type : VECTORS
    Target Body : Solar System Barycenter [SSB] [0]
    Coordinate Origin : Sun (body center) [500@10]
    Time Span : Start=1650-01-01, Stop=2180-01-01, Step=1 MO
    Table Settings : quantities code=1; reference plane=BODY EQUATOR; CSV format=YES
    Display/Output : plain text

    This will give dates, x, y, & z.

    3. Lag z by 20 years.

    4. Smooth lagged z by twice Jupiter’s period (which is 11.8663089875917 years according to NASA J2000).

    That will get you close enough to see what TB’s doing. Maybe then you can inquire about what other little tweaks TB has done.

    Note: I’m not judging TB’s claims here. I’m just helping you with calculations to expedite your discussion with TB.

    Now: These (TB’s) are VERY simple calculations that take only a few minutes. The solar-terrestrial-climate weave graph I’ve shared (that summarizes how the solar cycle subtly nudges decadal westerly wind anomalies) requires substantially more quantitative sophistication. If you are serious about understanding and willing to engage in respectful, sensible dialog, let me know. This sea level thread might not provide the optimal time & place for productive discussion, but I’m sure WUWT &/or Climate Etc. will give other suitable occasions for incrementally advancing exchanges as time passes.

  127. Paul Vaughan says:

    addition to Paul Vaughan (May 18, 2012 at 12:39 pm) …

    By the way, Tallbloke, if you’re reading here:

    You can get the SAME pattern amplified by a factor of 10 in the (x,y)-plane with a SIMPLE rotation of the coordinate frame (like I told you years ago). In a spreadsheet this literally takes only a few seconds:

    =+X*COS(THETA)+Y*SIN(THETA)

    Claims that the pattern can only be found on the z-axis are perfectly false. Much worse: Such claims indicate shallow or absent conceptual understanding of spatiotemporal aggregation criteria basics.

    This is not an attack on tallbloke. I’m simply seizing this perfect opportunity to again warn everyone to redouble their efforts to avoid costly ignorance of spatiotemporal aggregation criteria fundamentals.

    Apologies to Paul Homewood for going off-topic to address quantitative issues raised by AGF & tallbloke. Mr. Homewood: Thanks for an interesting article that has impacted my medium-term climate exploration priorities.


    jayhd [Jay Davis] (May 18, 2012 at 6:30 am) wrote:
    “By figuring the average – there’s the rub. Extraordinary events, such as Northeasters and hurricanes among other things, cause extraordinary surges that have nothing to do with sea level. These events really skew the results if we simply figure the averages. And the smaller the number of gauging stations used, the bigger the bias these one-off events introduce. Unless this issue is addressed adequately in the methodology used, any “average” computed is absolutely worthless. Especially if we are only talking about millimeters!”

    Well-said generally speaking, but far from being “worthless”, with very careful attention to aggregation criteria that stuff is THE SIGNAL, NOT the noise. (Maybe we just need to rename the variables under study.)

    “Apart from all other reasons, the parameters of the geoid depend on the distribution of water over the planetary surface.” — N.S. Sidorenkov

    Best Regards to All.

  128. Larry Butler says:

    I apologize for not being a scientist, but I’ve lived on the water most of my 67 years, many of which I owned or had access to some very substantial dockage, exactly the kind all the sea level guages around Charleston, SC, USA are mounted to. I’ve actually visited all these crudely-made instruments-mounted-in-plastic-pipes around here. EVERY dock, EVERY ONE, without exception, SINKS into whatever you drive its pilings into…even bedrock. They sink a lot! Some sink right out of sight, others simply fall over as the pluff mud is always moving, a thick liquid.

    My lack of education in these matters aside, I bet every tide
    guage ever deployed will tell you the sea level is rising lots more than the tiny few cm quoted in all these sea-level-is-rising pronouncements…NOT because the sea level is rising or falling, but because the DOCK IS SINKING!

    By the way, I asked around several professional mariners and we have a CONCENSUS on this observation, which I know is much more important these days than evidence and science….

  129. Bill Price says:

    The CRC Science Panel said SL has been and is rising and land subsiding, for net SL rise trend of 18″/ 100 y for the NC Outer Banks.
    Dr. Pilky says 1′ foot rise could cause up to 2 miles of inundation of tidelands.
    Comparing surveys from the 1850’s, 1900’s, 1950’s with today doesn’t seem to show much if any inundation.
    Why?
    Bill Price / Pine Knoll Shores NC.
    PS: Why are there many millions in Government grant funding to prove SL is rising in Greenland, Antarctica, the Himalayas and other exotic locals, but no grant funding to study the US coast line?

  130. Bill Price says:

    Mr. Homewood ,
    You note, the tidal gauges at Sheerness in the Thames Estuary show an increase since 1970 of 1.3mm/yr.
    I understand there are paintings of the Tower Of London – Water Gate from the 1600 or 1700’s.
    Does comparison with current views show SLR, or has the “Pool” been so greatly modified as to
    be unreliable?
    Thanks ,
    Bill Price – Pine Knoll Shores, NC

  131. agfosterjr says:

    Larry Butler says:
    May 19, 2012 at 2:39 pm
    ==============================
    Well there’s obviously only one thing to be done: put all the gauges on floating docks! Seriously, your comment threatens to cast doubt on the tide gauge record as bad as AW has cast doubt on the T record. And pk reports a drop of 23 feet in 10 years! I wonder if that’s a coastal record (I’m aware of 100 feet in 70 years in Cedar Valley, Utah (http://www.sltrib.com/ci_14705878). Makes sea level insignificant. –AGF

  132. Paul Vaughan says:

    @agfosterjr

    I’m drafting a coarse outline of methods. It will take weeks, maybe months due to competing vital obligations. In the meantime, here’s a summary of the weave using a different method: http://i49.tinypic.com/2jg5tvr.png .

    =
    Does anyone have a link to (plain-text-webpage-format) sea-level data resampled to equally-spaced?

  133. pk says:

    agfosterjr:
    the drop i referred to being at Long Beach Naval Shipyard, was owned up to by standard oil when the U.S. Navy took them to federal court. it was attributed to pumping oil out from under the southern end of terminal island during the middle 40’s to the middle 50’s. SO antied up about $1.5 million to stabilize a large dry dock (they built it up about 20 feet [remember that by the time the court case was over with the area had risen somewhat from steam/saltwater injection] as it was, the north end of the machine shop was still about 14′ lower than the south end when they closed the yard in 1997).

    c

  134. More on the clustering of the database sites:
    Brest and Newlyn are only 200 km apart! Rasey above

    It turns out that 3 stations: Santa Monica, La Jolla, San Diego are within 180 km
    All are within 120 km of the San Andreas main fault, without measure to the splinter faults.
    La Jolla is a day’s walk from San Diego, less than 20 km.

    Now the 3 stations in Florida are Pensacola – Fernandia – Key West
    which makes a nice 550 km, 680 km, 800 km triangle.
    For the 1900-2000 span, the range is 2.16 – 2.51 mm/yr (a diff of 0.35)
    But for the 2000-2011 span, the range is -3.36 to +2.82. (a diff of 6.18 mm/yr)
    Somewhere the rock is moving, not the water. Either that or there is more noise in the system than an 11 year trend can detect.

    Brest – Marseilles – Trieste make a triangle of
    890 – 780 – 1420 km

    Brest – Fernandia, FL = 6700 km
    Pensacola – San Diego = 2930 km
    Santa Monica – San Francisco – 580 km
    San Francisco – Honolulu – 3800 km
    Honolulu – Trieste = 12,703 km Over the North Pole.
    Actually, Trieste – San Francisco is shorter = 9750 over (Great Circle over Iceland)
    (all measured by Path tool in Google Earth).

    So there is quite a gap in Eastern Hemisphere data between Trieste and Hawaii.
    All points are North of the Equator.

  135. agfosterjr says:

    Paul Vaughan, thanks for your time. You can reach me at Yahoo. –AGF

  136. Yes! Yes! Yes! More underground water is drained to sea; more snow on mountains is melted than added and drained to the sea as water. Sea level rise is not due to GW though. GW and CC are two consequences besides many other. For details about the cause and solution to CC please visit to devbahadurdongol.blogspot.com

  137. I blundered onto a FAQ page from the PSMSL website. It had some assertions about how salinity, currents, winds, and temperatures change the sea level 1 to 2 meters, thats 1000 to 2000 mm, from the geode at different places around the world.

    Permanent Service for Mean Sea Level
    http://www.psmsl.org/train_and_info/faqs/

    [1]…These currents lead to differences between the MSS and the geoid of 1-2 m, even after averaging out time dependent motions such as tides. The differences in the MSS generated by the currents means that the Atlantic is 1m lower on the north side of the Gulf Stream than further south.

    [3]Sea level is about 20 cm higher on the Pacific side [of the Panama Canal] than the Atlantic due to the water being less dense on the Pacific side, on average, and due to the prevailing weather and ocean conditions. Such sea level differences are common across many short sections of land dividing ocean basins.

    [4]…Note also that the tides have opposite phase on the two sides of Panama, so, if there was a sea level canal, there would be major tidal currents through it. </blockquote

    All this was in response to a comment from David Springer on ClimateEtc in reference to a rather blocky sea-level curve from Aten-Bollich-2002-Fig30,
    http://www.texasbeyondhistory.net/coast/images/ap7-Aten-Bollich-2002-Fig30.jpg

    Kinda hard to get excited about even 3 mm/year when currents might provide 2000 mm of noise. But even if you want to get excited about 1 mm/year or 3 mm/year vs 10 mm/year (CAGW view), you have to have A LOT of tidal gauges to filter out current and salinity noise. 24, even if evenly space around the world on stable cratons, doesn’t provide nearly enough redundancy to reduce the standard error of the mean. it is the same issue Willis has with NOAA’s alleged temperature precision of the ocean from even thousands of Argo floats.

Comments are closed.