Dave Burton writes:
Those NASA guys are tricky.
Click the “Update: Sea level change / Ocean rising at 3.42 mm per year” link in their latest Newsletter and you’ll see the big, bold “3.42 mm/yr” near the top of the web page, and two very similar-looking graphs of sea-level: one from satellites, and one from tide stations.
Since only one rate of sea-level rise is shown, the casual observer is likely to think that the same 3.42 mm/yr rate applies to both graphs. Here’s a screenshot:
http://climate.nasa.gov/vital-signs/sea-level/
But the 3.42 mm/yr rate does not apply to both graphs. Look closer at the scales, and do the arithmetic, and you’ll realize that the 2nd graph is actually showing a slope of only about half that claimed 3.42 mm/yr.
Since the late 1920s it shows a slope of about 1.8 mm/yr, with no evidence of acceleration. But those tricky NASA guys scaled it to look like the slope is about the same as the first graph. It’s pretty obvious why they didn’t show a rate of sea-level rise for that graph.
What’s more, the second graph is not really just from tide gauge data; it’s from tide gauge data inflated by a +0.3 mm/yr GIA “adjustment,” to subtract off the rate by which the sinking ocean floor is hypothesized to reduce sea-level rise. The real rate of coastal sea-level rise from averaged tide gauge measurements is only about 1.4-1.5 mm/yr (under six inches per century), and that rate hasn’t increased since the late 1920s.
What’s more, even NASA’s first graph, of satellite altimetry measurements, is deceptive. Like the second graph, it shows a rate which has been inflated by the addition of model-derived GIA, plus by combining the various satellite measurements it also hides the wide variations in rates measured by different satellites.
AVISO has a much more informative graph of satellite altimetry measurements, showing a rate of +2.87 mm/yr, without GIA adjustment, here:
Warmest regards,
Dave
” Look closer at the scales, and do the arithmetic, and you’ll realize that the 2nd graph is actually showing a slope of only about half that claimed 3.42 mm/yr.”
Yes, but they are almost entirely non-overlapping periods. The tide data is from CSIRO. The more recent Church and White (CSIRO) paper on tide gauges is here And it rose in both satellite and tidal about 51 mm from 1992 ro 2009. That is 3 mm/yr.
http://www.moyhu.org.s3.amazonaws.com/2016/4/church.png
NS, then you need to reconcile NASA (sat alt), NOAA (tide gauges), and CSIRO SLR metrics (dunno, seems a hodgepodge). Not me, I published on this already. You.
“NS, then you need to reconcile NASA (sat alt), NOAA (tide gauges), and CSIRO SLR metrics”
No, this post alleges a discrepancy between CSIRO and NASA. I (and Church and White) show there is no discrepancy when you look at consistent time intervals. It seems, BTW, that the answer is acceleration.
NS, please provide some traceable evidence. Cause I looked hard and did not find any, exxept for the geostationary tide gauge/sat alt discrepancy discussed elsewhere. Verifiable data only.
ristvan,
“NS, please provide some traceable evidence.”
This follows a familiar pattern. Post appears where some scientist is said to be finding contrary to the consensus. I point out where same scientist says, no, that isn’t what he’s saying. I am then castigated for quoting such an unreliable source.
Here we have a CSIRO plot presented whose trend is supposed to contradict a NASA plot. But NASA data is from 1993-present; CSIRO from 1870-2000 (which means Church). So it can’t contradict. I produce a figure from a well-known more recent paper from the same authors, in which they explicitly examine the question of correspondence with satellite data in an overlapping period, and find that it is in good agreement, and also agrees with the trend (3.42) quoted here, especially if you add the IGA adjustment, which C&W didn’t use. That, apparently, is now not “traceable evidence”. The authors have become non-persons.
Here is their full range plot, with satellite overlaid:
http://www.moyhu.org.s3.amazonaws.com/2016/4/church.png
And here is how they describe the trend in words. 2.8 mm/yr since 1993, and that is without IGA.
” the linear trend from 1880 to 1935 is 1.1 ± 0.7 mm year-1 and from 1936 to the end of the record the trend is 1.8 ± 0.3 mm year-1 . The period of relatively rapid sea-level rise commencing in the 1930s ceases abruptly in about 1962 after which there is a fall in sea level of over 10 mm over 5 years. Starting in the late 1960s, sea level rises at a rate of almost 2.4 mm year-1 for 15 years from 1967 and at a rate of 2.8 ± 0.8 mm year-1 from 1993 to the end of the record. There are brief interruptions in the rise in the mid 1980s and the early 1990s”
Oops, I gave the URL of the previous plot. Here is the full range
http://www.moyhu.org.s3.amazonaws.com/2016/4/church1870.png
My sea wall was built 8 inches above high tide…..76 years ago..
according to those graphs….high tide should be over my sea wall now
It is not, it is still 8 inches below the top of my sea wall.
Lat, my family, me included as a kid, built our seawall in 1946 [70 years ago] but the highest fine weather king tides [normal BP] used to come about an inch over and trickle into the well if we didn’t keep a levy bank around it.
The wall and well are still the same but in recent years those highest king tides are 4 to 10 inches lower.
Nick, you and F T M are certainly right that NASA should have extended the 2nd graph (“ground data,” i.e., tide-gauge measurements) to the present, like the first graph. The fact that they didn’t does make comparisons harder.
But if they had done so, the discrepancy between the graphs would have been even more obvious. The tide gauge measurements of sea-level have shown no evidence of sea-level rise acceleration since the satellites went up. The sea-level trend has been almost perfectly linear.
The rates of SLR vary with location, but not significantly with time, at least since the 1920s. Inspection of graphs of sea-level measurements from the best tide gauges shows no sea-level rise acceleration, neither since 2000, nor since 1993. Here are some examples:
Denmark:
http://www.sealevel.info/130-071_Fredericia_2016-04.png
Australia:
http://www.sealevel.info/680-140_Sydney_2016-04.png
Germany:
http://www.sealevel.info/120-022_Wismar_2016-04.png
Honolulu, HI:
http://www.sealevel.info/1612340_Honolulu_2016-04.png
For the tide-gauge measurements to actually be consistent with satellite altimetry, the rate sea-level rise would have had to have approximately doubled, approximately when the satellite measurements began (1993). But that obviously didn’t happen. If it had actually happened it would be apparent in all those tide-gauge records.
The folks at NASA & CSIRO try so hard to find evidence that acceleration that sometimes they look downright silly. Here’s an example from a 2009 NASA JPL climate symposium (I added the red circles):
http://www.sealevel.info/JPL_Fu_sealevel_noise_spikes_Slide47_cropped.png
Look at what they did!
http://www.sealevel.info/JPL_Fu_sealevel_noise_spikes_Slide48_cropped.png
As for Church & White 2011, what they reported wasn’t really sea-level. Rather, it was sea-level measurements massaged and adjusted by model-derived estimates of GIA, and groundwater extraction, and dam impoundment. (Plus, they like to use a lot of short tide gauge records, of which I disapprove.) The fact that their “sea-level rise” estimate is so strikingly different from what the best tide gauges actually measure suggests that the late John Daly’s observation is even more true today than it was when he said it:
Dave,
“The fact that they didn’t does make comparisons harder.”
Yes, but then you claim
“the 2nd graph is actually showing a slope of only about half that claimed 3.42 mm/yr”
Yes it does. Because it is a different period. It’s just a fact about the time series.
“Rather, it was sea-level measurements massaged and adjusted by model-derived estimates of GIA, and groundwater extraction, and dam impoundment.”
Mainly it is a reconstruction using EOFs. Which is necessary if you want to get a global average, which you can use to estimate sea volume (which is where GIA etc come in). The ocean as seen by satellite looks like this
http://www.moyhu.org.s3.amazonaws.com/2016/3/sealevel.png
Variations of up to 180 mm, which is large compared to tidal gauge variation (long term). . A global estimate has to be able to track that – coastal tide gauges give only a small part of he picture. You can get information from that small part only if you know the prevalent patterns in the rest. That is why they do a EOF-based reconstruction. The motivation is not to improve on the satellite measures, but to extend back beyond them in time.
As to the individual tide gauges, you need to have some way of aggregating the information. Just showing subsets of four or so doesn’t help. The Church/White method is one way. People like Jevrejeva and co do various similar things, with similar results, as in Fig 6 of C&W. It isn’t just CSIRO.
Nick Stokes: “Yes it does. Because it is a different period. It’s just a fact about the time series.”
Seriously? More tediousness – do you really believe that not only every paper that supports your view is correct, but that everything said in every paper that supports your view is correct?
It’s quite impossible to take somebody seriously who defends every single claim and statement just because you want them to be true.
I wrote, “the 2nd graph is actually showing a slope of only about half that claimed 3.42 mm/yr”
Nick Stokes replied, “Yes it does. Because it is a different period.”
No, the difference is not “because” it is a different time period. As you can see from any of the best tide gauge records of sea-level, the sea-level trend did not change when the satellites went up. There was no acceleration.
Nick also wrote, “coastal tide gauges give only a small part of he picture.”
It’s the only part that matters. Sea-level rise in the mid-ocean doesn’t matter.
That’s one of the problems with satellite altimetry: it measures the wrong thing. For instance, If the upper layer of the mid-ocean warms, the water will expand, and the surface will rise. Satellite altimeters will (if they’re accurate) detect that and report it as sea-level rise, contributing to the global average.
But it’s a strictly local effect. It’s a “bulge” in the ocean, like a iceberg but less dramatic. It doesn’t affect sea-level elsewhere. It doesn’t affect the coasts.
http://burtonsys.com/climate/iceberg_1521870c_annotated.jpg
That’s a fundamental problem with the use of satellite altimetry to measure sea-level. If GRASP ever flies, it might help fix some of the accuracy issues with sea-level measurements by satellites, but it can’t fix the fact that satellites measure the wrong thing.
Dave,
“As you can see from any of the best tide gauge records of sea-level, the sea-level trend did not change when the satellites went up.”
You are comparing two measures of global sea level and complaining of inconsistency. Individual tide gauges, even the very best, are not measures of global sea level.
“Sea-level rise in the mid-ocean doesn’t matter.”
Of course it does. People want to relate sea level rise to warming. They are trying to estimate total volume of ocean. That is why GIA is essential. In the same way as if you are trying to estimate volume of liquid in a graduated flask, and the flask has thermally expanded. You have to adjust for it.
You seem to insist that they should be talking about something else. But they aren’t. They are talking about mean global sea level.
Nick Stokes loves him some reconstructions and adjustments, don’t he?
Nick,
People want to relate sea level rise to warming.
So? Who says they are right to? Who says what they want is the right approach? Why can’t regional observations count? It doesn’t make any sense to me.
In some areas the sea level rise will be because the continent is rising–or the crust is dancing–or because the sun beats down on the equator in the middle of the nowhere ocean and the sea level bulges. what’s wrong with those anomalies?
Nick Stokes says: “The motivation is not to improve on the satellite measures, but to extend back beyond them in time.” And “People want to relate sea level rise to warming. They are trying to estimate total volume of ocean. ”
I would offer a version of an old homily:
‘Lord give me the strength to measure what I CAN measure, the patience to accept what I can NOT measure, and the wisdom to know the difference.’
The only sea level data that are reliable are those tide gauges which are verified as stationary by GPS data. Stokes knows this, but try to get him to say it out loud. There are lots of them.
“Sea level” is complex. And, actually there is no such thing as one Sea Level.
Why does someone like Stokes with his impressive resume of professional achievement continue with this process of assassinating his own character?
Must need the money…
If it were true.. Yeah for fish ! Too bad Hollywood 1 percenters with your Malibu waterfront, you will just have get the servant’s to move the sun beds up a few feet just in case . Phew the stress, the responsibility .
.3mm = .018 inches
3mm = .18 inches
I’m skeptical on being able to make any decisions on weather the world is coming to an end on numbers such as these. Call me a denier.
Wylie Baths (opened in 1907) is one of many tidal baths or “rock pools”, that were built in my home town of Sydney. I learned to swim at Wylie’s (see below) during my early youth in the early 1950’s. The tidal baths are still in existence today and used by the public, despite the supposedly accelerating “rising” sea levels, due to CO2.
http://www.australianstockimages.com.au/images/photos/eb64s_ml.jpg
OSTM/Jason-2 Products Handbook
2.3.1. Accuracy of Sea-level Measurements
Generally speaking OSTM/Jason-2 has been specified based on the Jason-1 state of the art,
including improvements in payload technology, data processing and algorithms or ancillary data
(e.g: precise orbit determination and meteorological model accuracy). The sea-surface height shall be provided with a globally averaged RMS accuracy of 3.4 cm (1 sigma), or better, assuming 1 second averages.
The following table provides a summary of specifications and error budget at the end of the verification phase.
Significant wave height 10% or 0.5 m (f)
(f) Which ever is greater
More on GRASP – search WUWT for “Finally: JPL intends to get a GRASP on accurate sea level and ice measurements”
Forgot the link for the J-2 Data Products Handbook
http://www.aviso.altimetry.fr/fileadmin/documents/data/tools/hdbk_j2.pdf
The GPS reference frame is maintained by checks with ground monuments whose precise locations are established and maintained by measurements from the GPS system. I’ve never been quite as sanguine about the inflated precision claimed for all this stuff as the guys whose checks depend upon that precision being widely accepted.
Many years ago I believe that an Egyptologist named Flinders Petrie
was caught filing down stones from the Great Pyramid to make them
fit his particular theory. His perfidy only affected a few hundred scholars.
NASA is lying to the entire world and costing billions in economic damage
to keep this UN dead cat bouncing for ever more boodle to waste and
power to snatch.
Does no one understand that NASA’s current function is to support the administration’s “story line”? Instead of criticism, I think NASA deserves our admiration for doing such a fine job of that function in spite of raw data that makes their goal extremely difficult; less imaginative souls would have thought, “impossible”. Think of the strain those boys and girls are laboring under:
“Damn, Roy! The President ain’t gonna’ like the looks of this! Fix it!”
NASA, NOAA, IRS, Dept of Labor/Bureau of Labor Statistics, DHS/Customs and Border Protection, Dept of Labor, EPA, FCC, …just to name a few of the politically corrupted agencies in the current US executive branch where the leadership are political appointees doing the political bidding of a politicallly corrupt President, who also happens to be a serial liar himself. Tom Karl and NOAA & NASA are just doing what Lois Lerner et al at the IRS were encouraged to do… that is lie for the cause, and subjugate your honor for the President’s ego.
@Joel O’Bryan, please don’t get me going on Lois Lerner and for that matter Mrs (“What does it matter” Clinton.
If NASA are going to free themselves from accusations of intentional manipulation of the presentation of this data, then they are going to have to include the 1990 to present derived from ground data.
Also they should make it clear that the adjustment of +0.3mm/yr is NOT sea level rise.
If an adjustment is made to show what SLR would, should or could be doing if the world were not the place that it is – then this is not a measure of what people may conventionally understand to be SLR.
Even CSIRO seem to be in on this attempt to misguide the media and policy makers.
It is almost impossible to find a simple single representation of the record derived from coastal gauges for the entire length of the record, using their site.
This is not to suggest that global SLR can be simply derived from averaging the coastal gauge sites.
BUT – if acceleration is present globally, then it will be clearly evidenced by acceleration in the upward trend at the sites where sea level has long been measured.
Unless we were to imagine that uplift at all of these sites has correspondingly accelerated to match the rate of SLR acceleration.
I’ve looked at heap of coastal SLR graphs, and they are generally consistently linear.
However, CSIRO have managed to find one that is not in any sense representational and THIS graph from Manila (see link) is the graph that they have chosen as their example for their website.
Either, a troubling coincidence, or willful cherry-picking and intentional misdirection of the public.
Since the Manila graph must surely be just about the least representative graph of the lot!!!
A quick google search reveals a possible explanation:
“The entire Metro Manila is sinking by several centimetres per year, estimated as one metre in four years, said Siringan, adding that in northern suburban Malabon, a fishing area compared to Venice, has been sinking by 10 centimetres a year.”
It’s hard not to conclude that both NASA and CSIRO are attempting to play games with our minds…
http://www.cmar.csiro.au/sealevel/sl_meas_tide_gauge.html
I complained bitterly when the U.C. Boulder folks made that hike in sea level to account for their contention that deepening ocean beds under the added weight of rising water was masking what absolute sea level otherwise would have been. I’ll note they only got that bright idea after absolute sea level began an embarrassing retreat and the “adjustment” they came up with was just the right amount to restore the preceding rate of sea level rise. Even if they had gotten it right, their “sea level” chart title should have been changed to “sea volume”.
“Even CSIRO seem to be in on this attempt to misguide the media and policy makers.”
I think you have the tail wagging the dog.
Great observations, indefatigablefrog!
It is amazing that CSIRO chose that misleading Manila graph. Archive.org shows that they’ve been using it as their example for at least eight years. They’re remarkably shameless!
I think Manila is the 2nd-least-representative sea-level record. The 1st is Seward, Alaska. They really did experience alarming sea-level rise in Seward!
http://www.sealevel.info/9455090_Seward_2016-04.png
NOAA used to have a graph or Manila sea-level on their site, with the bold-print warning that, “This station has two different mean sea level (MSL) trends due to apparent subsidence,” and dashed vertical lines bracketing the post-1970 surge, with the note that, “dashed vertical lines bracket any periods of questionable data.”
In late 2014 or early 2015 they removed it altogether, presumably because of data quality concerns:
http://tidesandcurrents.noaa.gov/sltrends/sltrends_global_station.shtml?stnid=660-011
I hardly know what to make of this analysis of the situation in Manila.
The internet contains a variety of references to the vulnerability of Manila to “climate change” and sea level rise.
As you and I are both aware, it is unlikely that the oceans have begun to form a new heightened region exclusively around Manila since 1960. “The Great Manila Ocean Bulge”!!!
So the alternative explanation – subsidence – is preferable to requiring the revision of all physics.
Tectonic and anthropogenic subsidence each in good measure perhaps, as a guess.
I didn’t really care all that much, until I encountered this “scientific paper” which proposes that the sea level rise in Manila must be caused exclusively by the elevation of sea relative to the static coast.
A claim born of the need for victimhood, transfer of blame and hope for international appeasements in the form of big heaps of cash money from the U.N. – perhaps.
The willful conflation of SLR acceleration and gauge movement represents a downward trend in standards in science. They do explicitly “state” that they are confident that the suddenly increased rise is NOT the result of land subsidence – (honestly – WTF?) At the start of section 3.2 page 6.
So in that case, the poor people are Manila are all threatened by a giant ocean bulge monster created by evil climate change caused by the rich west. Yeah, yeah, we get the picture!!! Have some money then…
http://www.int-res.com/articles/cr/12/c012p097.pdf
indefatigablefrog wrote, “They do explicitly “state” that they are confident that the suddenly increased rise is NOT the result of land subsidence… section 3.2 page 6.”
Wow. Just wow.
But I guess it’s no worse than erasing the entire MWP on the basis of a handful of American bristlecone pine trees and one Siberian larch.
The text prior to the CSIRO graph for Manila states:
It appears they are using Manila as an example to NOT use for SLR.
Thanks for that observation John.
Then they are totally forgiven.
And apologies for my not paying close attention.
How absurd though that this curio then lead me to discover a “scientific paper” which was explicitly claiming the opposite.
It sure is a crazy mixed up world.
My understanding is that the satellite altimetry data used in modelling the trend in mean sea level is periodically recalibrated to match the gradient of a select set of tide gauges. If this is indeed the case, can anyone advise the tide gauges used for the model time rate of sea level rise?
‘data inflated by a +0.3 mm/yr GIA “adjustment,” to subtract off the rate by which the sinking ocean floor is hypothesized to reduce sea-level rise’
Classic case of the “result” taken hostage by the assumptions in your model.
NASA Schmasa, they are a black hole for money, burning millions and claiming false success is their game, please remember their origins are Nazis, NASA was pretty much Nazi run and staffed after WWII.
Feynman said NASA lied through their teeth about the reliability of the Challenger to get more funding, which resulted in deaths. That is NASA, repeatedly making claims not backed by solid science.
We have NO idea of sea levels beyond gauges, lets be honest, we just do not have enough data and don’t understand too much, more science of great uncertainty pushed as very certain.
Sea level rises only matter to us on land, so tide gauges are the only rational option, no one cares if the sea has rises 3 to 4mm per year in the pacific and Atlantic if Tide gauges are not showing it, the water needs to kind of appear at tide gauge measurements after all, if the land is under threat from rising water levels.
Again like the global average temp, global average sea rise level means nothing and like GAT is a residue of changes we dont understand.
NASA are taking us backwards scientifically. BTW GIGO was only ever going to claim success, after all that money they spent, anyone notice how all of these massively expensive experiments seem to never meet complete failure, like the LHC GIGO BICEP2 and MANY other lines of research, no one admits defeat or that they went down a dead end because unfortunately no scientist likes to spend a few years doing a study spending millions of tax payer cash, only to fall flat on their faces, BICEP2 was a perfect example “Just because we were wrong doesn’t mean we were wrong” 😀
Such arrogance, and people still to this day believe they went to the moon in a dish washer. ROFL
They were nazis they lied, propaganda was their thing, NASA produces propaganda for the US gov
Yes I am a crazy tin foil hat wearing crazy 🙂 Only an idiot looks at those photos and footage and believes they are legitimate, they fear the VA belt in 2015 but waltzed through it in a tumble dryer decades ago.. makes sense
I don’t see a ‘Sarc’ tag, but I hope this is a spoof. Mods?
Mark wrote: “Feynman said NASA lied through their teeth about the reliability of the Challenger to get more funding, which resulted in deaths. That is NASA, repeatedly making claims not backed by solid science.”
The Space Shuttle Launch system was perfectly reliable as long as you don’t launch in freezing temperatures. The cold weather on the day of the Challenger Disaster launch prevented seals on the solid rocket boosters from sealing properly (a known issue) and caused the destruction.
Engineers who worked on the solid rocket boosters did everything in their power to get NASA to delay the launch that morning, to no avail. Their science told them it was dangerous to launch under those conditions.
Solid science wasn’t the problem, it was bureaucrats in NASA who were determined to launch even under these dangerous circumstances, for political reasons.
I have looked on sea level trends since 1750.
Ed Caryl had a very good description of what is shown by tide gauge data since 1800. (NoTricksZone April 2014) It is called Mean Sea Level (MSL), which is corrected for Post Glacial Rebound (GSR PGR).
And Physical geographer F.J.P.M. Kwaad has written a paper: Sea level change in the Middle Ages and the Little Ice Age (2012?)
What I found was this.
1750 – 1810 : 0,1000 mm pr year 0,6cm (after graph for Amsterdam half tide levels)
1811 – 1860 : 0,4142 mm pr year 2,1cm (Caryl)
1861 – 1890 : 0,9133 mm pr year 2,7cm (Caryl)
1891 – 1920 : 2,1949 mm pr year 6,6cm (caryl)
1921 – 1950 : 1,9615 mm pr year 5,9cm (Caryl)
1951 – 1980 : 0.7133 mm pr year 2,1cm (Caryl)
1981 – 2013 : 2,2624 mm pr year 7,5cm (Caryl)
Some very interesting differences in trends that I have not seen discussed. What kind of natural variations?
Sea level rise 1750 to 2013: 27,5cm
Amsterdam 1800 – 1930: 14 cm (Caryl: 13.4cm) Support the assumption that Amstrdam tide gauge is fairly representative.
These measurements show a sea level increase the last 260 years. In contrast to air temperatures they can show a much more steady ocean warming and ice melting. What is most surprising is the great uptake of energy in the climate system between 1891 and 1920.
Satellite data: 2011 – 2016: 5,557 mm pr year 2,8cm (Colorado sea level)
It is Colorado data for 5 years, 2011 – 2015. Could NASA be bold enough to show tide gauge data for the same period?
Colorado sea level data is calculated from raw data. Mean data for 2015 minus mean data for 2011.
The GIA adjustments are utterly scandalous. The basin stretching is a real world real physical occurence and, like every other real physical occurrence affects the actual sea level rise. This kind of bullshit could lead to the bizarre situation where sea levels were actually physically falling but these numpties would be stating they were “rising”. Ridiculous.
By the same principle, it would be possible for altimeters to tell us that the snowy surface of Antarctica was rising – whilst declaring that this proved that the ground underneath was rising even faster, buoyed up as the ice above melted – thus proving – net ice loss.
So,all the data goes into a big black top hat, and then we shake in a little magic sparkly GIA powder – and out comes climate change acceleration catastrophe. Every time. Well, every time unless your name is Zwally the magnificent, in which case the same trick produces net ice gain. Whoops.
I don’t expect that he’ll be asked for a repeat performance, after that fiasco.
Speaking of being tricky, on NASA’s kid page, they have a page that says “why is the earth is getting warmer” and then they proceed to show the Antarctic ice core graphs of temp and CO2. On this page, there is not one mention of the temperature leading the change while CO2 follows. I find this grossly misleading.
http://climatekids.nasa.gov/climate-change-evidence/
If they aren’t careful, they might become known as the National Association of Scan Artists.
One thing that leaps to my mind is the use of a “Glacial Isostatic Adjustment” (GIA) for Global Sea Level data – as if we were emerging from a snowball earth with globally distributed glaciers.
It’s like saying “this end of the seesaw has risen six feet, so the other end must also have risen six feet at the same time.”
The use of a GIA for *global* data is simply wrong.
I THINK what they are saying is that the extra 120 metres of water added to the oceans by melting of the NH ice cap has caused, and is still continuing to cause (because the underlying mantle is viscous and takes time to fully adjust) the ocean bed to sink isostatically by 0.3 mm/year. And this of course would be a global thing, unrelated to icecap-melting isostasy.
What they HAVEN’T said is that if we make the (not unreasonable) assumption that seabed sinking is not contracting the earth, then there has to be a corresponding rise in the land of 0.7 mm/year. The oceans make up 70% of the earth’s surface so the calculation is simple.
So there’s a 1.0 mm/year reduction in mean sea level, relative to mean land level (0.3 mm sinking sea plus 0.7 mm rising land) due to isostasy that should be applied to the satellite sea level if you want sea level RELATIVE TO LAND (which is the number that matters to those of us who live on the land). It would bring the satellite SLR down a lot closer to the tide-gauge SLR.
Tide gauges are of course situated at the coast, so they would be at a sort of hinge between rising land and sinking sea, and wouldn’t be much affected by these isostatic effects.
In detail, it would be much more complicated, but my head is aching already.
Tricky is the new normal, along with FOI stonewalling, advocacy truths, and agenda science.
“The physical reason for the necessity of this adjustment to the atimetric satellite measurements of global sea level rise is due to the fact that, due to the large mass of water that was added to the ocean basins during the last deglaciation event of the Late Quaternary ice-age, the ocean basins are continuing to subside of average by this amount.
I’m assuming that the adjustment that Nerem has been making to his analysis of the satellite altimetry observations is this adjustment that I have previously shown to be required. Presumably he has referenced my original papers in deciding to inlcude. It has always been inlcuded in the analyses being perfomed by the group of Anny Cazenave who is the leading European scientist working in this area.
There should be nothing controversial about the necessity of making this correction. Since the need of it was established 10 years ago I’m surprised that it should be attracting attention!”
— Dick Peltier, June 19, 2011
Is this the argument for adding 0,3mm pr year to rising sea level? It seems strange. Could anybody explain the logic of this to me?
From CU Sea level research group, Colorado University.
“We apply a correction for GIA because we want our sea level time series to reflect purely oceanographic phenomena. In essence, we would like our GMSL time series to be a proxy for ocean water volume changes. This is what is needed for comparisons to global climate models, for example, and other oceanographic datasets.”
Also from Colorado University: “Prior to release 2011_rel1, we did not account for GIA in estimates of the global mean sea level rate, but this correction is now scientifically well-understood and is applied to GMSL estimates by nearly all research groups around the world. Including the GIA correction has the effect of increasing previous estimates of the global mean sea level rate by 0.3 mm/yr.”
Perhaps not so strange that they will not have gps corrected sea level data, when the GIA correction is such a holy cow”
Could anybody explain where the 0.3mm of ocean floor material goes?
It causes land to rise elsewhere, especially in places like Skagway and Vaasa:
http://www.sealevel.info/9452400_Skagway_2016-04.png
http://www.sealevel.info/060-051_Vaasa_2016-04.png
Bangla Desh has been of particular concern, because of its large population very close to sea level. However, being at the mouths of both the Ganges and Brahmaputra Rivers, it receives a considerable amount of silt from the Himalayas every year, so that it is conceivable that its area is actually increasing despite generally rising sea levels. Is there any data on this?
It was pointed out at a climate conference in Guelph a few years ago that alluvium tends to settle, which in itself would tend to make BD shrink over time, if it were not offset by the fresh silt factor. Meanwhile, tidal gauges would tend to sink relative to the underlying bedrock, making them an ambiguous fixed point.
In 2015-16, there were some minor border adjustments pursuant to a 1974 treaty that added about 40 km^2 to Bangla Desh, so that any comparison should end in 2014. There should be good data on the area of East Pakistan from 1947.
How much is caused by Bangladesh, being on the northeast edge of the tiny African plate, going under the massive Eurasian continental plate at the rate of 2 mm per year?
[But Mt Everest (on the Bangladesh plate’s intersection under Asia) is going “up” by 6+ mm/year. .mod]
Exactly. So what are the consequences to Bangladesh? And does the CAGW crowd propose to alter tectonic plate movement with CO2 administration?
I am working in Bangladesh at the moment.- looking at climate resilience in the southern part of the country.
At three sites (Hiron Point (in the delta), Cox’s Bazar (further south) and Diamond Harbour (across the border in India) the rate of rise was circa 4 mm/year. At Khepupara and Charchanga in the delta it was 14.8 and 8,8 mm/year respectively.
The values are based on tide data from the PSMSL site.
CSIRO’s cited webpage does now contain the gauge data up to 2015, along with the satellite data. The gauge data actually increases a little faster than the satellite figures since 1993. See http://www.cmar.csiro.au/sealevel/downloads/CSIRO_GMSL_1880_2015.pdf .
I’ll try to link this below, but may not quite remember what I’m doing:
Didn’t work. Perhaps some else could link it correctly?
Can anybody explain how the shape of the satellite orbit is determined and the accuracy of the oblate spheriod shape of the earth (42km or 26mi shorter in diameter at the poles from the equator ) is determined and how these non perfect shapes affect the SLR satellite measurements?
That’s funny, because NOAA’s website claims that global sea rise is only 1.7-1.8 mm a year.
I’ve posted an analysis of the CSIRO data on my web site at:
http://www.climatedata.info/discussions/blogger/
My conclusions are:
– The average rate of sea level rise from 1880 to 2013 is 1.6 mm/year
– The rate of sea level rise is not constant. It is increasing at 0.014 mm/year/year.
– Superimposed on the rising sea levels is a cyclical component with a periodicity of about 50 years which is synchronous with the Atlantic Multidecadal Oscillation.
Ron, 0.014 mm/yr^2 for 84 years would be 7.8 inches by 2100.
But I’ll bet that acceleration is mostly prior to the late 1920s. Run your quadratic regression starting in 1925 or 1930, and I’ll bet you’ll get a much lower figure for acceleration.
Appreciate your posts, Dave.
Thanks for the comment.
As you suggested, I split the data set into 1880 to 1930 and 1931 to 2013. The acceleration for the first period was -0.0162 mm/year/year (note, it was negative) and +0.0158 mm/year/year for the second period.
Thanks, Ron, that’s interesting. From the graph it looks like there was a “step acceleration” in that graph right at about 1930. So either starting or ending at 1930 wouldn’t capture it.
I suspect it’s an artifact of the particular tide gauges they chose. Most individual gauges show only a very slight change in trend, if any at all, at 1930. Many of the longest gauges show a slight increase in SLR trend somewhere between 1850 and 1930, but not nearly as striking as is seen in the Church & White graphs.
One subtlety to Church & White’s approach is that they like to do a minimum-variance unbiased estimator quadratic regression. That basically means that they take into account the error bars on the data, and put a lower weight on the fuzzier data points when fitting the quadratic. I have some Perl code to do that, here:
http://www.burtonsys.com/climate/jnathaz1/codeanddata.zip
—- it’s from tide gauge data inflated by a +0.3 mm/yr GIA “adjustment,” to subtract off the rate by which the sinking ocean floor is hypothesized to reduce sea-level rise. The real rate of coastal sea-level rise from averaged tide gauge measurements is only about 1.4-1.5 mm/yr (under six inches per century), and that rate hasn’t increased since the late 1920s. —-
Since the purpose (at least as far as it affects the population of the world vs. purely academic purposes) is to determine the supposedly disastrous effects on the population of the world, the sea level data should not be adjusted. What is important is the height of the sea, not the volume of the water in the oceans.
Even if we take the highest estimate of 3.42mm/year, that is 34cm per century – about a foot – in sea level rise. If I remember correctly, the past century had a sea level rise of about 17 inches (don’t remember the cutoff dates). So, they are saying that sea level will rise slower than it did in the past 100 years, and the alarmists are saying mankind will stand around with their ankles wet and not make any adjustments in a century.
(Hundreds of years ago the Dutch figured out how to raise land from the sea.)