Guest post by Paul Homewood
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.
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.
Figure 1
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).
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.
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.
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.
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.
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
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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.
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.
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.
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.
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.
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
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.
@ur momisugly 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
@ur momisuglyferd berple Re @ur momisugly 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.
@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
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.
@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.
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.☺
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
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
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?
Kim2000
Yes, I have included Newlyn in the analysis.
Paul Vaughan:
perhaps i should have shot my mouth off about hurricane surges also.
aaaaah well.
C
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.
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
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
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.
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
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
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?
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.
@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.