Yesterday, at 2:07 PM CA time (4:07 PM EDT), Rob Spooner posted the following comment in the Unthreaded n+2 thread:
http://www.climateaudit.org/?p=5978#comment-353931
I’ve been asked to move a comment to this thread (or unthread), so here it is. I have run into a small problem with some NASA methodology. Looking at http://climate.nasa.gov/keyIndicators/ and just eyeballing the graph on the right, Sea Level Change 1993-present, I find that the data corresponds very closely with a straight line that they helpfully provide. The straight line begins at 1993.0 and end around 2009.5. It rises from about -23 mm to + 20, or 43 mm during a period of 16.5 years.
The caption reads “3.4 mm/year (estimate).” Now my methodology for getting the average would be to divided the rise of 43 mm by the 16.5 years, but that gets 2.6 mm/year. NASA would seem to be using some other methodology. Not division? I guess it’s something so important I wouldn’t understand.
My curiosity led me to look at the link indicated in the comment, and I happened to download the graphic to which he was referring to examine it more closely:
[For whatever reason, the right hand side of the graphics was clipped when downloaded despite the fact that they looked normal on the NASA website.]
Rob was in fact correct that his assertion that the trend listed in the graphic did not reflect either the slope of the trend line nor the change calculated using the two endpoints of the series.
Normally that would be the end of the story, however, I happened to visit the site again this morning. To my surprise, the graph now looked like this:
There was an indication that the graph was updated 08.20.09, but no other indication that anything had changed. I don’t know if Rob had informed them of the error or whether they had “coincidentally” discovered it themselves.
The changes in the graph are interesting. The rate for the historical data on the left dropped a remarkable 30% 15% overnight from 2 mm/year to 1.7 mm/yr and the latest data trend dropped a more modest amount. The vertical scales changed in both graphs (150mm does seem more impressive than 15 cm). The source for the latest data plot also seems to have changed presumably accounting for the change in scaling.
Anyway, I am glad to see that the sea levels are not rising as fast as they were yesterday…
Climate Audit 
160 Comments
I have been corresponding with NASA about this and many other errors on that page since July 19th, to no avail.
I have submitted a formal Request for Correction per The Quality of Information Guidelines. They have acknowledged receipt of this formal request but have not responded.
The only change since July 19th is that the changed the text above the Sea Level section from “last updated 7.15.09 to “last updated 7.51.09”
============================================
My use of the feedback form on the webpage resulted in this August 5th response from the site manager:
It was shortly after that they I filed an official request for correction.
Re: Charlie (#1), maybe informality works best. I just picked a name at random from the NASA site, hoping to find somebody with some knowledge, and wound up with evidently the right person. He seems to have taken my comments more to heart than your formal request.
However, there are still two odd things. The first is that the graph from 1993 is not just a little longer time period with new scales. It’s an entirely different set of data. Although the caption still reads “Inverse barometer applied,” just like yesterday, this is a graph with inverse barometer not applied. I don’t actually understand why that would cause such a large change in a two-decade-long slope, and maybe some expert reading this can fill me in. But clearly, there are two datasets the produce remarkably different slopes and this is the one that yields the steeper one.
But not quite steep enough for the alarmists, so they helped it along. The new source, which as Phil notes is no longer Colorado but “AVIS,” uses the data and arrives at 3.33 mm/year “by applying the postglacial rebound correction (-0.3 mm/year).” Say what?
Turns out that the bottom of the ocean is dropping because dry land formerly under ice sheets has been rising since the end of the last Ice Age. So this “correction” changes the definition of sea level to some height above the average bottom of the ocean, which is certainly not what most educated people would expect.
If you take away the early years of the century, the rise from about 1930 was fairly steady around 2 mm/year. The satellite measurements, which may have contributed something due to solely to technology, have shown about 3 mm since 1993, maybe 1 mm faster than before. The extra .3 mm is an additional 30% and comes very close to fraud.
The AVIS site contains the following statement: “Precise monitoring of changes in the mean level of the oceans, particularly through the use of altimetry satellites, is vitally important, for understanding not just the climate but also the socioeconomic consequences of any rise in sea level.”
The USA is not metric, so this is hard for me, but it looks the ocean is rising relative to land about 3 mm/year, 3 cm/decade or about an inch. The “socioeconomic consequences” of the rising seas, of which about .4 inches per decade are at most attributable to global warming, seem pretty hard to discern.
Interesting — apart from the change in origin and scale, new new graph on the right looks like a smoothed version of the old graph on the right.
BTW,
Wouldn’t that be a drop of 15%?
RomanM: Yeah, I hadn’t finished my first cup of coffee when I wrote it … but I found the error myself and fixed it without being told. 🙂
Re: Hu McCulloch (#2), “new new graph on the right looks like a smoothed version of the old graph on the right. ”
Actually the data has a different hyperlink for the data source. The older webpage used the U of Colorado data with 60 day smoothing but without plotting the actual data points.
See http://sealevel.colorado.edu/current/sl_ib_ns_global.jpg for the graph that fits the description of “seasonal signal removed, inverse barometer applied”.
At first glance, it appears to be the same satellites, but slightly different processing.
Now they are using CLS/CNES/Legos as the source with 6 month smoothing after removal of annual and semi-annual signals.
I’ll wait a day or two to see what what other changes they have made, and then do another look at it.
—————–
My formal Request for Correction also had some general requests about doing an appropriate review of the HADCRU3 data, so I won’t be surprised if that gets changed to GISS.
My request also contained the suggestion that they add Ocean Heat Content graphs, with the same sort of Historical + Current format, the the long term study showing the 3 most cited long term Ocean Heat Content reconstructions and the short term showing ARGOS data.
—————————-
My philosophy was that while guys like Steve McIntyre and Hu McCulloch were looking in detail at peer-reviewed papers, that I’d take a look at what is being disseminated to the general public using our tax dollars.
I have several other projects going, where first I start with informal inquiries and requests for correction, with more formal follow-ups as required.
Charlie
One of my suggestions in the formal Request for Correction was that the historical graph be relabeled in mm rather than cm.
I suspect that the request has actually made a difference.
After making the intial submission, I added a few items, including the “-38% per decade since 1979” on the Sea Ice section of the page Global Climate Change. That particular item hasn’t been corrected.
Nor has the bogus smoothing of the Global Temperature Graph been corrected. The last 3 years of the smoothed line are perfectly flat. Even with the 20 year smooth of the CRU homepage there is a downturn.
Other interesting items on the page include the Sea Ice Extent in March 2009 being 5.85 million sq km. (It was actually a bit more than 15 million sq km).
The above list is not exhaustive — it is incredible how many errors that page has.
Romanm:
By my calculation after inputting the data in R and pleading with UEA to release the data, is that 2mm per year to 1.7mm per year is a 15% reduction. Auditors need to be extra careful, like people who live in glass houses!
Re: bernie (#4),
There are three types of mathematicians: those who can count and those who can’t.
Re: romanm (#7),
Mathematics doesn’t have much to do with actual numbers anyway. Arithmetic or Physics well they are concerned with actual numbers.
The reason the right end of the images is truncated is that it is actually a separate image on the NASA site.
Re: deadwood (#5),
I can see that now. The right side is called SeaLevelGraphicAnim.jpg. It allows the dot to flash and displays the latest value on a rollover.
It’s curious the new graph makes their alarmist point even more. The first set of graphs (and data) show a 70% increase in the rate of change in slope, while the second set of graphs show a whopping 96% change. Clearly Global Warming is real and we’re destroying the planet. But then after all, what good is a set of graphs if it’s not sufficiently scary?
The change to mm helps their point as well. A lot of people ignore the units and only look at the number, so 150 mm is more scary than 5.9 inches. Remember, perception is reality, even if reality is not scary.
As far as the historical data is concerned they’ve actually added new data back to 1870 and on to 1993.
Re: Phil. (#9),
Also as far as the right hand graph is concerned they reference a different source rather than the University of Colorado.
Re: Phil. (#11), you say:
Unfortunately, the link is, not to put too fine a point on it … is dead. I hates it when they do that. No such file exists.
Their filename in the link is given as:
There is nothing in the folder that says “PGR_Adjust”. There is one with “GIA_Adjust”. Are they the same? Who knows. I assume that they are adjustments for isostatic rebound, but I don’t know.
w.
Re: Willis Eschenbach (#48),
I downloaded the file earlier and did some calculations using R. I think the GIA file is the one you want. The trend matches the advertised value and the plot is identical. The ncdf file contains a time variable as days since 1950 in increments of approximately 10 days. The NoGIA has a trend exactly .3 mm /yr less so in fact GIA refers to the glacial adjustment – presumably PGR is GIA in French. The other sets as I recall involved seasonal adjustments.
Re: Frazzled (#54),
So do us a favor. Hunt up a link for the summary of the paper and post it here. That the way this cooperative effort works.
Re: RomanM (#55),
Good point! You only had to ask… Paper here (subscription wall): http://www.nature.com/nature/journal/v457/n7228/full/nature07675.html
News and Views here (subscription wall): http://www.nature.com/nature/journal/v457/n7228/full/457391a.html
Paper Abstract:
The annual cycle in the Earth’s surface temperature is extremely large—comparable in magnitude to the glacial–interglacial cycles over most of the planet. Trends in the phase and the amplitude of the annual cycle have been observed, but the causes and significance of these changes remain poorly understood—in part because we lack an understanding of the natural variability. Here we show that the phase of the annual cycle of surface temperature over extratropical land shifted towards earlier seasons by 1.7 days between 1954 and 2007; this change is highly anomalous with respect to earlier variations, which we interpret as being indicative of the natural range. Significant changes in the amplitude of the annual cycle are also observed between 1954 and 2007. These shifts in the annual cycles appear to be related, in part, to changes in the northern annular mode of climate variability, although the land phase shift is significantly larger than that predicted by trends in the northern annular mode alone. Few of the climate models presented by the Intergovernmental Panel on Climate Change reproduce the observed decrease in amplitude and none reproduce the shift towards earlier seasons.
News and Views Abstract:
It’s cold in winter and hot in summer. But the latest analysis illustrates the need to put observational data at the forefront of attempts to achieve a more detailed understanding of the annual temperature cycle.
Re: Frazzled (#59),
hmm. Read the paper, a few paragraphs in I found that they used CRU data. Stopped reading. CRU data is anecdotal. there is no access to the CRU data sources or methods. Next.
Re: steven mosher (#89),
Ouch. No possible response to that criticism. OK, I will henceforth give up any pretense at justifying climate science as a discipline but I will confidently base all my future actions on Schumacher winning in F1. Oh bugger…
Re: Frazzled (#123),
I wonder if frazzled knows I believe in AGW.
Re: steven mosher (#127),
The fundamentalist warmers consider the lukewarmers to be apostates. There is no warming but Catastrophic Warming, and Gore is it’s messenger.
Re: steven mosher (#89),
Actually, based on that profound critique, I’ve decided that science is useless. All progress is a heep of hooey. Big Bang? Big Boo. Evolution? EvoBollux! I know Mr Mosher didn’t mean it quite that way, but for heavens sake its enough to make even a hard core athiest gag!
I wonder if the satellite data has been compared to existing tide gauge data to ensure that the earlier data is robust OR visa versa. It seems fishy that acceleration occurs at the beginning of the use of satellites.
Re: jack mosevich (#12),
This is a favourite alarmist trick used by the IPCC as well as NASA. In fact if you compare apples with apples, according to a paper by SJ Holgate the rate of sea level rise from tide gauges over the last 50 years is …. 1.7 mm/yr!
They do the same with CO2 (click on ‘evidence’). Historic data from ice cores, where any short term changes would be smoothed out by diffusion, are spliced onto the modern direct measurements, to create a scary hockey-stick picture.
There’s no way that that’s the only tide gauge record they could have chosen (and notice it changed?), but they managed to get thirteen extra years, and now instead of some number of gauges, they just say it’s from CSIRO. Now here’s the best part-there is no reason why they would chose a particular record AFAIK, but they clearly have made a (subjective?) decision-these all are supposed to represent the same thing as tbey “historical data” graph. One of them is-possibly-the same!:
Now here’s the kicker: None of these seem to be in agreement with this:
or this:
Which are from:
Click to access S304-Shum_Global_Sea_Level_Rise.pdf
and
Click to access sealevel_change_poster_holgate.pdf
Respectively.
Somebody should audit these sea level “reconstructions”-I smell Hockey Team shenanigans.
Re: Andrew (#13),
In Andrew’s last link, Simon Holgate reports:
“Decadal rates of sea level change during the twentieth century.” Simon Holgate, Proudman Oceanographic Laboratory, Liverpool, UK, Natural Environmental Research Council
That appears to be a 26% reduction in rate of rise from the first to second half of the last century!
Curious how that is interpreted as a dramatic “increase” in ocean rise!
The time frame for the historical has been changed increasing the length of the period 13 years.
The trendline on the 3.33 curve does not look quite right. The area
above the trend-line and the area below should be about equal if a
linear regession is used. It does not look like this is the case
for the picture shown.
Re: Jim (#13),
As I mentioned in the post, the graph was cut off (as explained by deadwood) because the graph actually consists of two separate pieces. Lookinbg at it on the source web site is a better indicator of the fitted line.
Oh, by the way, I wonder if it’s pure coincidence the graph starts at about the Dalton Minimum, when temperatures had been the coldest in a while. Showing the rise from a minimum level is misleading, to say the least.
This leads to my blockbuster study soon to be released: “Gravitational Pull of Satellites cause Ocean rise: A Robustly Scary Study Demands Quick Political Action”
Maybe I’m missing something, but why are they comparing two different time frames? Why isn’t 1880 to Present displayed?
Re: Jeff Alberts (#19),
They are missing a good alarmist bet by not doing so. The combined graph would show a fairly large upswing at the joinpoint since the ratio between the vertical and horizontal scales of the graph on the right is twice that of the one on the left.
Re: Andrew (#20),
The newer spam filter is occasionally picking up comments posted by people on what appears to be a somewhat random basis. I have been going in to release them at periodic intervals.
From what I can tell, it appears from their data I have found on the Aviso web site that a correction is applied which increases the trend by .3 mm/yr:
Damn it. I haven’t been able to post comments in forever. I want to say that I have serious doubts about the “historical data”. I smell Hockey team shenanigans. The reason is that the “historical data” curve looks nothing like several others I have seen- sea level “reconstructions” if you will. It seems to be one of these:
Which don’t even agree with one another. Whatever the NASA curve respresents, it sure isn’t “global sea level change” with any where near the accuracy implied by a single curve without error bars…
http://www.guardian.co.uk/environment/2009/aug/21/climate-change-nile-flooding-farming
Found this today on the U.K. Guardian web site. Anybody know if there are geological reasons for the Nile delta sinking? After all, the SE of England is sinking (& the NW of Scotland rising) still due to rebound from the ice age.
Re: mstewart (#21),
This is OT, but I will try an answer: The Nile Delta is almöst certainly sinking, essentially all deltas are. The reason is that new sediments are continually added by the river and the weight causes srustal sagging. This is easily seen in the Mississippi delta where the depth to basement is almost 10 km in places.
However the current – and serious – erosion has little to do with either this slow sinking or sea level rise. It is an inevitable and indeed foreseen result of the building of the Assuan dam and (especially) the High Dam. This means that there is no longer any Nile floods, that deposits new sediment, instead the sediment settles in Nasser lake (which is silting up rather quickly). Meanwhile the sea keeps gnawing at the bars that protect the delta and which are not being replaced any longer. Ultimately there will be a shallow bay stretching up approximately to Cairo. Unless Nasser Lake fills up first, and the waters start spilling over the dam.
By the way essentially the same thing is happening in Louisiana where flood control keep the water confined the main channels, where sediment piles up higher and higher, while the delta erodes (exacerbated by subsidence due to oil and gas extraction).
Now all these things are perfectly well understood by geologists and hydrologists, but since remedies are very expensive and very impopular (like allowing the Mississippi delta to flood a couple of months a year) nothing is likely to be done.
By the way Egypt was never a colony (unless you count the Ottoman empire back in the early 19th century), so that bit about “colonial masters” is just PC doubletalk.
Re: tty (#27), I’ll accept Egypt being a colony when it was part of the Roman Empire.
Re: tty (#27),
tty,
You are right about the effect of the Aswan dam. If delta flooding is curtailed then, inevitably, the delta sediments will not be renewed and the sea will encroach. This has long been understood by geographers and others. But apparently not by Guardian journalists or climate campaigners!
Re: mstewart (#21), All river deltas sink unless sediment is added. as soon as the dams on the nile were built, the delta started to sink.
Re: mstewart (#21),
This is some data from Israel:
http://www.fig.net/pub/fig_2002/Ts4-6/TS4_6_shirman_melzer.pdf#page=9
The difference in the left graph appears to be b/c the original ran from a time period of 1880-1990 and the updated ran from 1880-1993.
If the extra three years reduced the trend by that much (over the course of 110+ years), one wonders why they didn’t just modify the graph on the right to start at 1990 instead of 1993. Seems that it would’ve amplified the trend, no?
Re: Scott (#23),
I believe that the satellite data they are using begins in 1993.
From the fact that the original value was given as 2 rather than 2.0, I would surmise that in fact the 2 mm./yr. represented a rounding of a value which does not differ much from the 1.7 mm. From the observation made by Bob H. (#9), it is clear that reducing the posted value for the Historical data amplifies the “increase” in the Latest data trend. The statement:
from the Evidence page has a nice ring to it.
This graph on wiki makes a similar comparison:
http://en.wikipedia.org/wiki/File:Recent_Sea_Level_Rise.png
With all of the “noise,” it would be amazing to see that there is a statistical difference in the trend.
hmm.
Click to access AIRSValP2doc.pdf
interesting document. The validation plan for SST and land surface temp is perhaps something of interest
to folks. Looking for the validation data now
Point 1:
I just love how all these temperature, CO2, and sea level graphs all seem to start sometime after 1860. 1880 or 1900.
There is lots data out there with temperatures, CO2 and sea levels from at least 1700. Funny how they always get ignored.
Point 2: Especially the Dutch (and all those areas shown in AIT) can now breath a sigh of relief.
Just an FYI the right way to capture images that are split (like this one was, it had an animated gif butted on the right end to make the dot blink) is to do a screencap and then crop the image.
For those who don’t know, here is how to do this:
1) center your browser window to the area of interest, making sure all is visible
2) Press these two keys in sequence while holding down ALT
ALT + PrtScrn
3) This copies the browser window as a bitmap to your Windows clipboard
4) Open a paint/graphics program and paste the clipboard as a new image using CTRL+V or Edit > Paste
5) Crop to area of interest, and save as a new graphic
Here is my result today:
Re: Anthony Watts (#30),
Good info! Thanks for the heads up, Anthony.
Re: romanm (#31), Anthony – For years, I had been pressing the same “al print screen” that you suggest for screen grabs. Then one day on a whim I tried just “print screen” by itself, and it worked exactly the same. “Alt” isn’t necessary.
Re: Navy Bob (#32),
That is only true for the smaller screen where the browser window is full screen. On bigger screen sizes like I run 1920×1200 I very rarely run te browser full screen.
PrtScrn gives you the whole screen to the clipboard
Alt-PrtScrn gives you the current active Window. I find it easier to deal with when I have just the Window capture to edit, but to each his/her own.
– Anthony
Re: Anthony Watts (#30),
If your not going to edit the screen capture you don’t need to open a graphics program. You can paste into any application that will accept images (Word, Wordpad, ect).
Re: Anthony Watts (#30),
Or you can download Gimp for Windows and use its image capture stuff.
Navy Bob:
alt+print screen captures the active window, such as browser. print screen by itself captures the entire desktop.
You probably didn’t notice because your browser took up your entire desktop.
Re: jeez (#34), jeez, anthony – You’re right – it does take up the whole screen – although it’s pretty big – 1440 pixels wide. I only use multiple windows when I’m multitasking, e.g., word, photoshop, web layout simultaneously.
If you are on a MacIntosh it is Shift-Command-4 and it lets you draw a capture window. The image is saved as a .png file on the desktop.
I would recommend clicking the NASA link, and then clicking the links for the respective sources. The source for the recent satellite data is a French organization (and even thought it’s not clickable, notice that the older data was from U of Colorado). What’s even more interesting is that the long-term trend is from some Australian organization who’s website has a clear whiff of activism (and note the caveats regarding data usage…), where the older version had no cited source at all.
It appears that they simply chose different sources from before. What the justification for doing that is, your guess is as good as mine. But there doesn’t seem to be any original NASA content in any of this, they’re just going out and picking sources from the internet.
Just out of curiosity, I took the University of Colorado Sea Level data (the raw data, seasonal signal not removed and no inverse barometer) and separated it into two sections, 1993 to 2005 and 2006 to 2008. The linear regression of the 444 data points from the 13 years 1993 to 2005 gave a slope of 3.46 mm per year. For the 66 data points from the three years 2006, 2007, and 2008, the slope was 2 mm per year.
I guess I needed something to do.
Data link: http://sealevel.colorado.edu/results.php
Sea levels are a little like sea temperatures and land based temperatures- historic ‘global’ data tends to be very sparse and is consequently interpolated, but the results are treated as scientific enough to be parsed to fractions. Also the parameters change frequently, so we may be comparing an apple with an orange rather than another apple. We also tend to place too much reliance on Satellites (short time scale and potentially inaccurate) or tide gauges (susceptible to changes in the local environment and not always well maintained)In other words each system has their drawbacks and the idea of a global sea level must be queried, let alone the precise figures that are produced.
This is is a recent abstract
M Ablain, A Cazenave, G Valladeau, S (2009)
“A new error budget assessment of the global
Mean Sea Level (MSL) determined by TOPEX/Poseidon and
Jason-1 altimeter satellites between January 1993 and June
2008 is presented using last altimeter standards. We discuss
all potential errors affecting the calculation of the global
MSL rate. We also compare altimetry-based sea level with
tide gauge measurements over the altimetric period. Applying
a statistical approach, this allows us to provide a realistic
error budget of the MSL rise measured by satellite altimetry.
These new calculations highlight a reduction in the rate of sea
level rise since 2005, by 2 mm/yr. This represents a 60%
reduction compared to the 3.3 mm/yr sea level rise (glacial
isostatic adjustment correction applied) measured between
1993 and 2005. Since November 2005, MSL is accurately
measured by a single satellite, Jason-1. However the error
analysis performed here indicates that the recent reduction in
MSL rate is real.”
This abstract comes from “Continental Shelf Research” and emanates from a well respected UK University-it is strictly a ‘local’ study but matches information from Proudman plus observations.
“Mean sea-level trends around the english channel over the 20th century and their wider context.
Ivan Haigha, , , Robert Nichollsa, and Neil Wellsb,
a School of Civil Engineering and the Environment, University of Southampton, Highfield Campus,Southampton, SO17 1BJ, UK
b School of Ocean and Earth Sciences National Oceanography Centre, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK
Received 1 May 2009; revised 23 July 2009; accepted 24 July 2009. Available online 8 August 2009.
Abstract
This paper provides estimates of rates of change in mean sea level around the English Channel, based on an extensive new hourly sea level data set for the south coast of the UK, derived from data archaeology. Mean sea level trends are found to vary by between 0.8 and 2.3 mm/yr around the Channel. The rates of mean sea level change are calculated by removing the coherent part of the sea level variability from the time series of annual mean sea level before fitting linear trends. The improvement in accuracy gained by using this approach is assessed by comparing trends with those calculated using the more traditional method, in which linear trends are fitted directly to the original records. Removal of the coherent part of the sea level variability allows more precise trends to be calculated from records spanning 30 years. With the traditional approach 50 years is required to obtain the same level of accuracy. Rates of vertical land movement are approximated by subtracting the mean sea level trends from the most recent regional estimate of change in sea level due to oceanographic processes only. These estimated rates are compared to measurements from geological data and advanced geodetic techniques. There is good agreement around most of the UK. However, the rates estimated from the sea level records imply that the geological data suggests too much submergence along the western and central parts of the UK south coast. Lastly, the paper evaluates whether the high rates of mean sea-level rise of the last decade are unusual compared to trends observed at other periods in the historical record and finds that they are not.”
Click to access Trends_section1&2.pdf
This is written by many of our old friends including Phil Jones and Mike Hulme-page 19 gives the sea level data. The information was ‘extended’ from a paper by one of the scientists at Proudman
http://www.pol.ac.uk/ntslf/products.php
This page provides access to the actual individual station records
http://www.pol.ac.uk/ntslf/trends.php
Various UK (cherry picked)stations such as Bournemouth and Devonport confirm the Uni’s observations whilst Fishguard extends it up the Welsh coast.
http://www.pol.ac.uk/psmsl/author_archive/jevrejeva_etal_1700/
above is reconstruction from 1700 which is the grand daddy of all sea level charts
Amsterdam from 1700 (van Veen 1945)
Liverpool since 1768 (woodworth 1999)
Stockholm since 1774 (Ekman 1988)
These three are taken to represent global figures since 1700 although much data is missing and has been subsequently imaginatively interpolated. It comments on the differences even in the same ocean basin between tide gauges of up to plus or minus 6cm
Click to access 2008GL033611.pdf
This is the pdf from 1700 link
There is much juggling and adjustment of figures on sea levels that are of a dubious provenance to begin with. Sea levels seem to rise and fall in cycles-just like temperatures and there is nothing to show that what is currently happening is out of the ordinary if looked at in a historic context
Tony Brown
Re: Tony Brown (#43),
Thank you for taking the time to provide links to various sources of sea level data and analysis. They should provide readers some orientation in the pysical complexities of sea level. The simplistic notion that thermal expansion of oceans or melting of glaciers chiefly drive sea level variations can scarcely survive even preliminary scrutiny. And the idea that for any geophysical variable a 15-yr “trend” can be meaningfully compared to a century-long one is mathematically misguided even under the best of circumstances. Here we have the circumstance of entirely different measurement methods, each with it’s own problems. They cannot be solved by simple statistics.
A large part of the claim that sea level rise is accelerating is because people are compairing tide guages from the past data to satelite altimetry for recent years. In fact tide guages still show a current sea level rise of about 1.8mm per year. There is an interesting graph on page 5 of this article that shows the divergence between satelite and tide guages http://earthobservatory.nasa.gov/Features/OceanCooling/ Other studies including GPS (Global and Planetary Change 57 (2007) 396–406) studies usually find the rate of rise to be about 1.8 mm per year. CARL WUNSCH has said in 2007 “Estimates made here produce a global mean of about 1.6 mm
yr1, or about 60% of the pure altimetric estimate, of which about 70% is from the addition of freshwater.
Interannual global variations may be dominated by the freshwater changes rather than by heating changes.
The widely quoted altimetric global average values may well be correct, but the accuracies being inferred
in the literature are not testable by existing in situ observations. Useful estimation of the global averages
is extremely difficult given the realities of space–time sampling and model approximations. Systematic
errors are likely to dominate most estimates of global average change: published values and error bars
should be used very cautiously.” And, “It remains
possible that the database is insufficient to compute
mean sea level trends with the accuracy necessary to
discuss the impact of global warming—as disappointing
as this conclusion may be. The priority has to be to
make such calculations possible in the future.” Journal of Climate 15 Dec. 2007
Re: Gary (#42),
There is nothing wrong with this a priori, what’s wrong is that they are comparing the sattelite trend of about 15 years length to the trend over the full length in a record which is over a hundred years long. Now if they compared the decadal trends throughout the tide guage records with with the handful you can find in the sattelite record, there is nothing odd going on at all:
Decadal rate of sea level rise from satellites (red curve) appended to the decadal rate of global sea level rise as determined from a 9-station tide gauge network for the period 1904-2003 (blue curve) and from a 177-station tide gauge network for the period 1948-2002 (adapted from Holgate, 2007).
Holgate, S. J., 2007. On the decadal rates of sea level change during the twentieth century, Geophysical Research Letters, 34, L01602, doi:10.1029/2006GL028492.
http://sealevel.colorado.edu/current/sl_ib_ns_global.txt
Re:
It’s ironic that NASA purposedly doesn’t use satellites’ temperatures to replace junk stations and prefer multi-adjusted satellites’ sea level data to replace perfectly consistent tidal gauges. Because in the former, it’s an inconvenient truth of cooling, in the latter, it’s a convenient lie of “near doubling of sea rise rate”.
It’s one more evidence, if neeeded, they know they are acting like exagerating advocates and not scientists.
“The hockey stick, Ee-Gore! It’s ALIVE! ALIVE!”
Ok, based upon the information available at the JASON-1 site, they set the change in ocean level from 1992 to present at 58 mm. So, for seventeen years, that produces the 3.4 mm/yr number they provided in the right graph. But if you just add that value to the entire record going back to 1870, that produces a trend line of of only 1.58 mm/yr. I believe we have a clear instance of cherry picking here.
If you take the numbers from the graph for 1870 to 1930, the trend looks like only 0.83 mm/yr. But most that increase came between 1870 and 1910, so the period of actual growth showed a rise of roughly 1.25 mm/yr. Between 1930 and 1950, the amount of growth equaled that of the preceding sixty years, representing a rate of 2.5 mm/yr. Between 1950 and 1990, the rate seems to have settled again, showing as something on the order of 1.5 mm/yr.
It looks like the rate of expansion has increased again in the near twenty years since the end of the first graphic. But we do have to remember that there has been a change in metric used here. The last twenty years have been based upon satellite measurement, while the preceding 120 were based upon tide measurement in selected harbors around the world. The general measurement standard for harbor tide gauges is not millimeters, but rather feet and inches in the English system, meters and centimeters in the metric system. The millimeter levels for the sea level metric were determined by averaging all of those measurement for the years across the entire world.
CSIRO, who provided the chart at the left, show error bars on the older data that are +/-50 mm. So it is difficult to say that the current rise is unprecedented, as the early data is not profoundly reliable.
The comparison is the last 15 years vs 120 years. Can someone cherry pick the highest 15 year period from 1870 – 1990 (I’m not sure how to do it statistically, but eyeballing says there would be equivalent periods to the present). It would be an interesting comparison.
Something I never see mentioned regarding sea level is that to determine sea level at a given point you must measure all high and low tides for 18.6 years. Sun, moon, earth gravity and rotation.
National Ocean Survey has a national network of tide gauges and records sea level about every ten minutes at every gauge. They made a national reduction of the data in 1960 and again in 2001. The NOS rep for Florida told me the rise was 3.5 cm.
I love this discussion – real science in action!
PS After all the Steig stuff on this site, I went back to that issue of Nature and couldn’t help but notice the Article (yes, Article, not Letter, i.e. Nature’s premier category of paper) in the same issue on changing seasons due to climate change. It also appears to have an accompanying commentary from a statistician. Did any of you auditors notice that?? Or do you only go for Team stories?? Anyway, your choice of course, but might be worth a look…
Re: Frazzled (#49), Call it what you will but Steve has always been primarily interested in the influential “mainstream” literature. I don’t think that study got much buzz, but “Antarctica is warming after all! Take that Crichton!” raised such a stir, I mean, how could we ignore it?
Not fair? Life isn’t fair.
Re: Andrew (#52),
Fair point, but you really should take a look at the Article before offering an opinion: I bet it will be much more central to the next IPCC report than the Steig Letter (it deals with issues of a much more global nature), which makes me wonder about your implicit reluctance to dig deeper.
It’s not all about “The Team” you know… plus the paper in question got almost as much press coverage as Steig’s Antartica story at the time (or didn’t you notice?). Anyway, I offer it as a suggestion… 22 January issue of Nature, with a News and Views commentary from David Thomson. A good read, especially if you dislike modelling!
Re: Frazzled (#54), I’m not reluctant to dig deeper. I’m not digging at all. It’s everyone else that has been doing the digging about stuff.
And no, I didn’t notice. I don’t pay that much attention. But that’s me.
Re: Andrew (#61),
You seemed pretty sure about what this site should/should-not be doing earlier.
I just take it at face value: an ‘audit’ site that should be concentrating on ‘auditing’ stuff that, in the grander scheme of things, need ‘auditing’. I was simply pointing out stuff that I thought had been missed. (Yes, there’s a lot of climate science out there, much of it inconsequential to the layman, but some carries more real weight than others, regardless of what impressions you get from press coverage…)
Re: Frazzled (#66), It is not reasonable to expect everyone here to both 1. Know how things work here and 2. Be able to do what everyone else here can do. I am sure how things work around here because I’ve seen people go through the motions, not because I have done the grunt work myself. If anybody takes interest, maybe that paper will be “audited”. It wasn’t before probably because everyone was wrapped up in other things. Or maybe it really isn’t that important, so nobody payed attention. What’s your damage anyway?
Re: Frazzled (#59), Let’s examine this closely:
Basically “whether the models suck or not doesn’t matter”. In other words no matter how much or how little warming their ultimately is, which we can only get out of models or guess work at this point, we should be alarmed. “the observational evidence for human influence on the climate system is overwhelming” 1. What is the nature of the “human influence” 2. What is it’s magnitude 3. Missouri. “Stine and colleagues’ paper adds to that evidence” In what way? Seems like such a detail is independent of the cause of any change, no? Especially since models get it wrong. “If we do not stop polluting Earth’s atmosphere” Emotional/political statement, not scientific at all. What’s the point of responding to such nonsense? Opps, “invective”…”we may not have enough time left to develop models sophisticated enough to show what is obvious in the data now.”-what is “obvious in that data” is that whatever warming is going on is proceeding at a slow enough pace to virtually disappear for twelve years. Such a slow motion emergency is not a “maybe” gonna kill us before we can model it-it’s definitely not gonna kill us before we get better models.
He’s a statistician, but he’s obviously also a political advocate. And he also has very little idea what he is talking about from what I can tell.
Re: Andrew (#74),
How can I respond to that, other than to say READ THE GODDAM MATERIAL!! Yes, if you just take the words in the abstracts (which I dug out on request, remember!) you can pick out phrasing or even sentences that in isolation will annoy. But surely this site is above that! It’s an “audit” site, for heavens sake, and the details MATTER!
I am not pushing an agenda here (although I do have my beliefs, which no doubt a [small] number of you will agree with)… but what I am pushing is intellectual honesty in these debates. And that means listening to dissenting views, and taking on board relevent information when it comes to light – even if that information is unwelcome in some sense (i.e. conflicts with your world view). That happens to me most days, so I am not expecting of others what I don’t expect of myself!
Well, its nearly 3am in Europe, so I am going to sign off now (yes, I’m a lilly-livered limey commie). But I do hope to rejoin this discussion again before too long… and that includes debating with you, kim!
Re: Frazzled (#75),
I commented on the “statistician”‘s quote. I did not comment on the paper. The paper looks interesting. Maybe I’ll comment on it in the future. Or maybe I won’t. But maybe others will. I just don’t feel the obligation-I’ve never “audited” anything in my (short so far) life. I come here for discussion not homework. I certainly didn’t accuse you of pushing any agenda (unless you are the mysterious “statistician”?)
And you should not make assumptions about the folks here. You have no idea what the distribution of opinions is.
Re: Frazzled (#78),
When all else fails, try Caps Lock?
Re: Frazzled (#57),
What is your opinion of all those AGW proponents who are actively working to prevent any digging at all? I’m referring to the on-gong obstructionist efforts of AGW proponents who refuse to release data, refuse to fully describe methods and procedures and refuse access to computer code. There is a side in this AGW debate that resists and resents “digging deeper” — but it isn’t represented by CA.
Given the current almost unprecedentedly average arctic and antarctic icecaps does anyone know where all this extra water is coming from?
1.7mm spread across the planet seems like quite a lot to me for it simply to have appeared.
Re: BrianMcL (#53),
It only taks a fairly small (relative to the total mass) annual loss of mass to the sea from Greenland and Antarctica and other land based ice to raise the sea level by a mmm or so a year. See Cazenave et al., 2009 for a total budget.
Changes in the phase of the annual cycle of surface temperature; A. R. Stine1, P. Huybers2 & I. Y. Fung1 is a copy of the Nature article that isn’t behind a paywall.
This non-climatologist’s impressions on first reading are:
1) A well written paper. Clear descriptions of what was actually done and what the results were. It seems more open and transparent than most articles.
2) They present both their findings and findings that aren’t 100% in agreement — for example the study of Central England Temps that show seasons shifting later, while this paper sees overall hemispheric shift of seasons in the earlier direction.
3) They observe that “Few of the climate models presented by the Intergovernmental Panel on Climate Change
reproduce the observed decrease in amplitude and none reproduce the shift towards earlier seasons.” and in the body of the text:
“The IPCC model results do not appear to give us an explanation of
the observed trends, except to suggest that the answer involves something
that the models do not capture. We thus retreat to a simple,
conceptual model to explore how local processes may cause variability
in l and G consistent with the observations.”
People are still doing real science.
Re: Charlie (#58),
Indeed! And to quote directly from the closing remarks of the accompanying News and Views (by a *statistician* I should stress, with reservations about the models):
Finally, independent of any shortcomings in the models, we must remember that the observational evidence for human influence on the climate system is overwhelming. Stine and colleagues’ paper adds to that evidence. If we do not stop polluting Earth’s atmosphere, we may not have enough time left to develop models sophisticated enough to show what is obvious in the data now.
Thoughts??
Re: Frazzled (#59),
The ‘observational evidence of human influence on climate’ is not overwhelming except regionally. The evidence of human influence by greenhouse gas effect is not there. Evidence of warming, by unknown cause, is there, so why shouldn’t seasons change? Besides, we’re cooling now; expect the seasons to regress.
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Re: kim (#63),
Sure, honey, when you think yourself capable of it.
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Re: kim (#63),
Thanks. Just what I/we were looking for.
Re: Frazzled (#67),
Heh, read it twice; more if necessary.
======================
Re: kim (#68),
Once is enough, chuck 🙂
Re: Frazzled (#69),
Sneers only persuade the gullible at certain blog sites. Please teach me what you find to sneer at in my critique.
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Re: kim (#70),
I see no critique, just partial invective. Critique I can cope with: read the paper (and News and Views) I mentioned earlier, then maybe we can discuss. I’ve read them, but that doesn’t mean I believe every word of them… but you probably already assume that I do, which does not bode well for sensible conversation. Shame.
Re: Frazzled (#71),
There is no invective, even partial, in comment #63. Can you respond to my critique of the paper you show us or not?
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Re: kim (#72),
[Sigh] What critique?? Give me some evidence that you’ve read the paper (AND News and Views), then maybe there’s potential grounds to engage… sorry to be blunt, but nothing in your former comments indicates that you HAVE read the material, and I’m not in the slightest bit interested in rhetorical arguments (although I feel that I’ve stumbled into one now, more fool me).
Sweeping statements of personal opinion presented as “fact” just don’t do it for me, regardless of the subject matter (except perhaps King Crimson, who are beyond criticism).
Re: Frazzled (#73),
How amusing; you’ve been disarmed and that paper delegged by four short sentences in comment #63. Shall I come closer?
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Re: Frazzled (#76),
I’m not sure that King Crimson are entirely “beyond criticism” but we’d have to debate this on another blog!
Re: kim (#66),
Eh, it’s #66 not #63 that lacks the invective, even partial, and has the four strokes.
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Re: Frazzled (#62),
Here’s what I noticed. They are quite explicit in that paper that the discovered phase shift isn’t likely to be from increased GHG’s. They suggest drier soil or possibly increased aerosols as mechanisms. So I’m not seeing how this is more evidence of man’s responsibility via GHG’s. Isn’t the paper in fact quite contradictory to that hypothesis? They seem in fact to be saying there’s something unnatural going on but it’s not CO2 or methane release. Thomson didn’t seem to spot that one.
I’m glad they acknowledged that “we lack a good model for natural variability”. Yes, quite! Tell that to Hadley and the IPCC because they’ve been trying to tell us for years that they could in fact model natural variability to the extent of being able to separate out man’s influence. And indeed that idea formed the major plank in the mountain of “evidence” that Thomson alludes to. Can we now all finally conclude that Hadley and the IPCC were in fact lying through their teeth about that?
Re: JamesG (#95),
Thank you! I finally feel that my modest efforts were not in vane! (I don’t agree 100% with your assessment of the paper, but that’s beside the point) The whole point of ‘auditing’ (as I naively see it) is that it should be across the board… singling out particular groups for abuse (Team Team Team [snip-language]) does nothing to further conceptual and/or scientific progress.
Re: Frazzled (#122),
Your efforts to measure wind direction?
Re: Calvin Ball (#126),
Spelling Nazi alert!
Re: JamesG (#95),
Hey, some people read papers! This is GOOD!!!
RomanM: Some of us read enough to know when the rest is not of interest. Enough OT! The next time this is brought up in this thread, it will likely disappear and leave no forwarding address.
Re: Frazzled (#157),
Thanks RomanM… I’ve been told and will obey 🙂
Re: Frazzled (#62),
Harrumph. All life forms alter their local environment in an attempt to enhance their own survival. In the biological world, it is survival of the fit enough to live long enough to reproduce; not survival of the fittest, and chance has a lot to do with which sets of individuals are fit enough at any given time and place. I am pretty sure that bacteria, single celled plants, fungi, multicellular plants, multicellular animals, and man; in that order, represent the order of the effectiveness of the biological alteration of Earth’s environment. We are simply *now* more aware of our own effects on the local environment. And we are at least one order of magnitude more aware of our own effects than we are of the effects of the other parts of the biological world.
That’s easy, 7/51/09 is 8/20/09, right? And there it is.
Also, extend the graph to the present and the recent rate of rise is even less.
There is something rotten at the seashore, and I can smell it all the way over here.
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Re: kim (#60),
Good ‘ol “kim” with his/her well-developed sense of smell. Can we have some serious discussion here??
Your post RomanM nudged me to finish an article on much the same data.
Intended to be fairly accessible, might be too chatty for some.
http://ccgi.flute.plus.com/thor/concept/weather/data-analysis/jason-and-sea-level/
Apologies if the server is very slow.
Re: Tim Channon (#68),
Will take a look at it tomorrow. it’s late here.
Frazzled and Andrew, please take a deep breath. An initial glance at the paper’s SI makes it appear that someone is fitting a simple sinusoidal curve to temperatures. I’m not sure why this should be of interest, but I will take a look at it as well.
I am sorry. The “before” and “after” data for the 1870 to 1993 plot are not the same. The differences may be subtle but they are real. I do not see mathematically how the shapes of the peaks and valleys can change from the “before” to the “after” without at least some of the raw data being different in the “after”. Can someone explain this to me? In my field of electrical engineering, we have a saying: the data are the data. Am I wrong?
Two quick thoughts:
1. They certainly have access to the U Colo sea level stats through July 2009, and that graphic shows 3.2 mm year sea level increase. Not much of a difference, but why not use the latest info?
2. I’d like to see one graph combining all the yearly sea level detail, so that we can see the context, e.g. the dip in sea level in the late 1980s, and see how that compares to the increases since 1993, when satellites began to measure sea level increase. Not an issue of accuracy, just of understanding the situation a bit better with one’s eyeballs.
The updated JPL NASA page lists CISRO as the data source and shows a historical graph that ends in 1993 with no overlap with the satellite data. In looking on the CISRO site, I find a graphic that combines tide gauges from 1870-2007 and has the satellite data overlaid for the last few years. In my opinion, this gives a more objective view of the total trend. From CISRO sea level homepage:
I’ll suggest to NASA that they use the graph with the combined tide gauge and satellite data because it puts the short term satellite data in clearer context.
Re: Charlie (#90),
And here it is obvious that the sea level increase from 1930 to 1960 was significantly larger than from 1960 to 1990, although the CO2 level skyrocked during the latter interval.
Hence CO2 has nothing to do with sea level increase, right?
If you follow the climate.nasa.gov sea level page back to the CLS/Cnes/Legos source of the bottom right figure in Roman’s post, you get to http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/, which has what appears to the source data, with both 2-month and 6-month smoothing, and 3.33mm/yr trend for the satellite data from 10/92-2/09.
However, there is an additional map-graph, with a caption that admits that there is a lot of regional variation, from as little as -10 to as high as +10 mm/yr. This makes the 3.33 mm sound more like a drop in the bucket, to be hyperbolic. (A quart in the bucket would be less metaphoric, but still it’s small in comparison to the total variation.)
The site has the data for both graphs.
The Caspian Sea seems to be included in the global sea level picture, even though it doesn’t connect to the rest of the “sea”.
Re: Hu McCulloch (#91),
HU’s second graphic speaks volumes. Anyone who remembers how mountains form and looks at that graph realizes immediately that the AGW crowd is preying on people’s ignorance with the sea level canard. The surface of the earth, from the bottom of the oceans to the tops of the mountains, is not stationary.
Who was it that used a single sea gauge (in Hong Kong?) to extrapolate doom and gloom sea levels in 100 years?
Re: stan (#93),
I have your tall tale beat.
80 meters! Can anybody top that?
Re: Hu McCulloch (#91), Nice addition, Hu, with that image of regional variability.
So what is the AGW explanation for the regional variation? Can “the models” reproduce it? Given the inability of “the models” to reproduce regional variability in temperature rise, I would imagine they fare no better reproducing regional variability in sea level rise.
My instinct would be look to long term trends in zonal versus meridional atmospheric circulation to explain this. But I only got through my sophomore year of climatology (actually, physical geography) before I switched to economics, so what do I know?
Re: Hu McCulloch (#91), interesting art you have there!
So ignoring the far reaching error bars (particularly locally), strong sea level rise seems to be concentrated in the South Pacific. Does this make sense physically? Is it simply the case for this time period due to El Nino events or something?
The band going across the Southern Hemisphere seems to alternate pretty quickly between dark blues and reds, as it does in a few other areas…which doesn’t seem to make a lot of sense physcally. I think that goes to reflect how much error needs to be read into the readings.
Re: Hu McCulloch (#91),
That second graph is indeed very telling.
Look at all that Southeast Asian glacier run-off!
Re: Hu McCulloch (#91), world map – could the biggest differences be due to the slow ongoing land rise still happening following the Ice Ages, which affected the Northern Hemisphere landmasses principally? NH rise, balanced by SH fall.
.
Re: Ecotretas (#132), heck Ecotretas, that looks like one helluva piece of work you’ve done. Recent sea levels falling !?? I want to see it on Watts Up. Pity your slide show is very difficult for some folk like me to look at on screen. Best format in my opinion is pdf with A4 “landscape” presentation (so that each slide/page fits the normal screen). Re: PaulM (#146), It seems that in the light of Ecotretas showing that surface stations actually show a recent overall FALL in sea level, (assuming he is correct) these corrections to the satellite figures sure need to be ferreted out and audited.
Changes in average barometric pressure and water temperature are the likely causes of regional variation of sea level. A comparison of the global plot of sea level to changes in SST over the same time span might be instructive. Gridded Argo data on average temperature of the top 700m would be even better, but it doesn’t go back that far.
Total ocean volume is the measure of interest for looking at the budget of melting land based ice and thermal expansion (basically ocean heat content). That’s the reason for the GIA correction.
“The vertical scales changed in both graphs (150mm does seem more impressive than 15 cm).”
More bitchin. The change makes the scales on both graphs consistent. You can’t help making nasty insinuations when you have no idea, can you?
Re: slownewsday (#98),
Yes, it does… and they just noticed that it wasn’t consistent before?
Am I wrong in thinking that waves form a componant in sea level measurements? If so, could some of these variations be due to different wave sizes?
DaveJR “Am I wrong in thinking that waves form a component in sea level measurements?”
The wave height or sea state does affect radar reflection, but this effect is removed during processing of the data. This is one of many, many corrections/adjustments during the processing of the data.
Table showing adjusts and Basics of Altimetry review the processing.
Just like in satellite measurements of surface temperatures, they do some sanity checks and correlations with measurements on the surface to try and get accurate readings.
Satellite data excels in the area covered and the density of measurements. Surface-based readings have more straightforward corrections, although as we have seen in the USHCN and sufacestations.org discussion, even just measuring temperature involves lots of processing.
Regarding the chart of spatial rates of rise – does anyone know exactly what the satellite sensors are measuring? It is distance from the water surface to the satellite, or is it thickness of the water? I’m having a really hard time picturing how the level can be rising on the west side of the pacific and falling on the east over that kind of timescale.
Re: Calvin Ball’s post 104. Can someone point us to the methodology of satellite surface elevation measurement.
I ask, because I understand that recent technology locating center of mass of earth relative to surface stations provides accuracy of 3mm of a slowly moving target. I imagine that satellite orbital geometry is driven by center of mass of earth and affected by other external forces as well.
So how could they be coming up with measurements that are smaller than the known locational accuracy of the satellites themselves? or are these sea level elevations derived by comparison with surface “bench marks?”
There’s something about the Present Data graph.
Has anyone noticed the 15mm bonus? Why does the chart not start at 0mm in 1993?
Re: Bob McDonald (#106), the problem isn’t the y-axis, which could be marked zero anywhere. The graph used to start negative and now starts positive. Doesn’t matter.
What matters is that the data on which the graph is based has “inverse barometer not applied” although the caption reads otherwise. For some reason that I can’t find, this substantially changes the slope.
And that a .3 mm/year “postglacial rebound correction” has been applied, tilting the line more steeply, although there is no indication (a) what it is, or (b) why it’s .3 mm/year, or (c) why anyone cares.
Re: Calvin Ball’s post 104. Can someone point us to the methodology of satellite surface elevation measurement? I ask because I imagine that satellites orbit the center of mass of the earth which oscillates and with current technology the location of center of mass seems known only to about 3mm.
Maybe they are using comparisons with land surface bench-marks, a practice which might compensate for orbital variations, but…..
oops. sorry.
Conversely, the fine detail of GRACE satellite measurements is being used to evaluate major hydrological changes. e.g.
Improvement of global hydrological models using GRACE data Güntner, A. (2008) Surveys in Geophysics, 29, 4-5, 375-397 DOI: 10.1007/s10712-008-9038-y.
“Mining” groundwater in India for irrigation is seriously dropping the water table with catastrophic projections (resulting in mass starvation), far more serious than (reasonable) consequences projected for anthropogenic global warming from CO2. See:
Tiwari et al. (2008) Variations in the total water storage in the major river basins of India from GRACE satellite gravity data, Eos Trans. AGU,89(53), Fall Meet. Suppl., Abstract : G13A-0646.
Big Gulp, Asian style: Increased irrigation is rapidly depleting India’s groundwater
See figures at: NASA Satellites Unlock Secret to Northern India’s Vanishing Water
Satellite data show Indian water stocks shrinking Groundwater depletion raises spectre of shortages. Quirin Schiermeier 12 August 2009 | Nature 460, 789 (2009) | doi:10.1038/460789a
Pumping 54 km^3/year of groundwater in India compared to ocean surface area of 3.6*10^8 km^2 is about 0.015 mm/year increase in ocean level.
i.e. Pumping fossil groundwater for irrigation in India alone causes 0.9% increase in the 1.7 mm/year long term rise in ocean level!
“Global groundwater withdrawals total 700-800 km3/year (Shah et al. 2000)” or 14 times as large (cited by: Konikow, L.F., and Kendy, E., 2005, Groundwater depletion: A global problem: Hydrogeology Journal, v. 13, p. 317-320.)
This suggests that about 0.2 mm/year, or 12% increase in the long term sea level rise of 1.7 mm/year, is coming from global groundwater depletion.
PS T.G. Huntington apparently addresses this issue in: Can we dismiss the effect of changes in land-based water storage on sea-level rise? Hydrological Processes Volume 22 Issue 5, Pages 717 – 723
Re: David L. Hagen (#112),
“In Water for food, water for Life: a comprehensive assessment of water”, David Molden (Fig. 10.1 p 399) shows groundwater withdrawal in India now exceeds ~254 km3/year.” (2007) Earthscan Pubs. ISBN-13: 978-1844073962
That suggests global groundwater depletion now exceeds 1000 km3/year or 0.27 mm/year rise in oceans.
That suggests agricultural groundwater depletion may contribute 16% to the historical 1.7 mm/year rise in ocean level.
(Anyone have quantitative current estimates of groundwater extraction?)
Inverse barometer correction means correction of sea level to constant barometric pressure, specifically 101,325 Pa. Consider a large body of water with varying barometric pressure across the surface. The surface level will be lower where the pressure is higher than average and higher where the pressure is lower. To a first order, a 1 mbar (100 Pa) change in pressure causes a 10 mm change in level. Hurricane storm surge is caused in part by the low pressure in the eye of a hurricane.
Re: DeWitt Payne (#112), OK, about what I figured. But it doesn’t explain how GSL can be affected over almost two decades by what would seem to be transitory effects. Is it not correct that the global average barometric pressure is essentially constant? Is it possible that in the early 90’s, high pressure was more common over the ocean and now is seen more often over land?
I’m just making stabs.
Re: Rob Spooner (#114),
Barometric pressure changes will have the most effect on the regional MSL (the lower chart), not the global average MSL. Thermal expansion is not likely to be evenly distributed globally either.
Re: DeWitt Payne (#112), Nitpicking…usually see HPa in meteorology, since the ration of HPa to mbar is 1:1
Re: Rob Spooner (#114), Doesn’t look like it to me:
http://www.cdc.noaa.gov/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Sea+Level+Pressure&level=2000&lat1=90&lat2=-90&lon1=180&lon2=-180&iseas=0&mon1=0&mon2=0&iarea=1&typeout=2&Submit=Create+Timeseries
Re: Andrew (#115),The graph you sent me to shows shows what appears to be global barometric pressure (I interpret all that stuff at the top to be saying “everywhere” the long way), then it does seem to show a downward trend. In which case, “inverse barometer removed” is going to accentuate the rise. It looks like the drop from early 90’s to mid 00’s is about .2 mb, or referring to the DeWitt Payne (#112) posting, about 2 mm. Or a bit over .1 mm per year.
Not a lot, and not enough to explain the difference between the graph on Thursday and its replacement on Friday. The remaining item is “seasonal signals removed” or not. How could this affect a multi-year plot?
Is it me, or did sea level rise just increase by around 10mm over 15 years from one graph to the newer?
From eyeballing the first graph is approx. 38mm over 15 years (2.5mm/year) and on the newer is approx. 47mm over 15 years (3.1mm/year).
My question is did the data set change, had they screwed up the first graph or did they change the scale to make it fit the 3.3 value they want? Secondly, how does someone manage to screw something up something a simple as a graph with a linear trend line and get published on the site with no one checking it? Dont NASA have QA protocals or review their work? If I made a mistake like that in one of my reports and it wasnt picked up in the peer review I would be chastised!
Re: Frazzled (#124),
Please continue this OT discussion in Unthreaded n+2 which is intended for such things.
I personally did not particularly find the papers that you suggested very interesting. Your statement that “auditing should be across the board” is somewhat naive since it does not take into account the time and resources available for the purpose. IMHO, with such limited resources, one tends to choose audits from papers (on either side of the issue) that make outrageous claims and/or are important from a standpoint of future usage in major documents or for policy decision making. As well, I also like to select cases where the statistics in the papers are either non-existent or misused. In such cases my skills are handy and it has the side effect of providing some education to others who may read the audit.
The two papers you suggested did not meet any of the criteria that I list above. The statistician (more an engineer with interests and expertise in signal time series) really did not say anything of substance. he seems to believe in AGW although he expressed some realistic observations which I and some others here might agree with:
End of discussion for me. Take it to unthreaded if you continue this with others.
Perhaps another downward adjustment is necessary.
Re: maksimovich (#128), Some weeks ago I emailed the first author, M. Ablain, asking what was used as a datum point for the measurement of sea level change. The reply was courteous and thoughtful and was stated (in my few words here) to be the frame of reference to which satellite orbits are measured.
It is interesting that the authors claim that sea level has not changed measurably for several years, with the implication that the estimated rate of change is slowing as the measurements get better.
There is also relevant data from several Pacific Islands at
http://www.globaleducation.edna.edu.au/globaled/go/cache/offonce/pid/3111
The last time I checked, a few weeks ago, the month of June 2009 (from memory) showed no change here either.
I also have a confusion about barometric corrections, unless there is a time-variant asymmetry of baro pressure over land versus sea. One might expect that globally, the baro effect overt he oceans would be constant when integrated over periods of years, with zero correction required.
Likewise, with thermal expansion, the temperature of the whole global ocean system has to rise before there is expansion. If the top 500 m are getting hotter, it remains a requirement to show that the lower levels are not getting colder.
There is some difficulty in believing old estimates of sea level change and I prefer the ones with new equipment especially designed.
Re: Geoff Sherrington (#147),
Inverted barometer corrections apply only locally , when the barometric pressure record is known. No correction is called for the global average, because the total mass of the atmosphere is invariant.
The interesting thing about the new Pacific Island observations you reference is that they show a dip in sea level during the super El Nino of 1997-98. So much for primitive notions of thermal expansion!
Maksimovich, 128, is there a link to the paper you quote?
Re: j ferguson (#130),
Try looking here.
Re: romanm (#131),
Thanks much. From reading the paper as well as others it referenced, I was able to understand how the system works and how the accuracy of its measurements were not premised on the intended orbit, but on the actual orbit as best discovered from the ground. This makes my concern about surface altitude determinations relative to geocenter locations moot.
Re: j ferguson (#133),
It also looks like at least some of the acceleration in MSL increase in the 1993-2008 period was related to the 1998 and 2003 El Nino’s. The reduction in MSL rate for 2005-2008 also confirms the nearly flat Ocean Heat Content curve over the same time period from ARGO data.
NASA’s data is quite tricky. They use data from only 23 tida gauges, and only until 1993. They then conveniently changed to satellite data.
Data from 53 tide gauges, till end of June 2009, distributed all over the world, suggests a decline of sea level by almost two feet, by 2100, if it continues the downward trend observed over the last three years. Even considering the average value for the last 9 years, this would lead to a rise of only one inch during the XXI century.
The original data and report is available through http://ecotretas.blogspot.com/2009/07/sea-level-decline.html
Ecotretas
Will this alter the prediction of 200 million climate refugees by 15%?
Really, bewteeen the absence of warming, absence of sea rise, absence of sea ice loss and absence of increases in all of the observations falsely attributed to AGW how does this charade continue very much longer?
To get back to the original thrust of this thread, the source from which NASA gets information for their Key Indicators post-1993 graph of sea level is AVISO (which I thought was AVIS until I realized that the globe at the end was a clever way of writing “O”). And AVISO’s graph is not a graph of sea level. It’s a graph of a proxy for ocean volume, which comes from adding .3 mm/year to the rise in sea level as reported by satellite altimetry.
The argument for this is that the subsidence of the ocean floor due to post glacial rebound of dry land (it’s essentially a zero-sum game) “masks” the true extent of thermal expansion due to “modern climate change.” If you’re doing research on this, it may be useful to know, but this is not a correction. It’s a redefinition. That’s OK, but not if you continue to use the same words.
“Sea level” in the minds of most people, and certainly all journalists, is the level of the sea relative to some standard. It is NOT the volume. When AVISO makes the adjustment without any explanation, and NASA repeats the result without even mentioning the adjustment, it’s plain intellectual dishonesty.
Re: Rob Spooner (#136),
The graph without the glacial rebound effect is
At first I thought that the glacial rebound effect should be removed, since it isn’t in the tide gauge data, but in looking more closely at the CISRO data the tide gauge record also appears to have a correction for glacial rebound added in.
I think the text on the JPL-NASA webpage about 23 tide stations is left over from the previous data source. The CISRO data seems to be coming from some papers by Church & White in 2006 and 2004. Links to the data and papers can be found at http://www.pol.ac.uk/psmsl/author_archive/church_white/
I haven’t yet checked to see if indeed this is the dataset used by NASA for the graph but they look the same in a quick visual check.
Church and White in their 2006 have this to say about trends and acceleration of sea level trends:
Using the higher number of 1.84mm/yr and adding in another 0.14mm/yr due to acceleration since of trend since 2001 has the estimated tide gauge rate at 2.0mm/yr in 2009. Still a long ways from 3.3mm/yr seen in the satellite record.
We will know in 20 years what is real, and what is merely short term and decadal variations, like those spread throughout the tidal gauge history.
Re: Charlie (#140),
Why wait? From Andrew (#48), I think that the fact that the satellite “acceleration” is clearly decadal variability can be shown now.
Re: Charlie (#141),
The glacial rebound correction for a tide gauge corrects for the local rebound not the global. A tide gauge is located on land. That particular piece of land may be rising or falling relative to the center of the earth due to glacial rebound effects.
Further to my earlier post 43Re: Tony Brown (#43),
Good succinct post Rob Spooner #136
We are being bamboozled by science which likes to have a nice graph to explain everything, unfortunately the real world is more complicated than that. Global sea levels are -like global temperatures-a nonsensical artefact dreamt up in a computer laboratory.
This is the latest IPCC assessment which confirms sea level calculations from 1993 are by satellite.(page 5 onwards)
Click to access ar4-wg1-spm.pdf
The sea level calculations rely on an enormous number of variable factors including pressure, location, tides, warmth of oceans, structures, storms, wave heights (which it detracts), surges, stasis, location of the gauge/sensor, slope of the underlying strata etc. The accuracy of measurements is said to be 3cm (10 times the level of the alleged annual rise) but in reality is often vaguer than that because of the inherent difficulties of measuring.
Observed real world sea levels generally simply do not show the rate of increase suggested by the IPCC (although this varies enormously from place to place for reasons cited above)
Both the following sites give a good description of the satellite process-which is being constantly refined- but doesn’t get significantly more accurate as the inherent flaws in measuring capabilities can’t be resolved.
Click to access 15_1_jacobs_et_al.pdf
http://jchemed.chem.wisc.edu/Journal/Issues/1999/dec/abs1635.html
The following sites deals with problems of satellite accuracy and data;
http://www.ocean-sci.net/5/193/2009/os-5-193-2009.html
http://www.climateaudit.org/?p=859
This with reliability;
http://lightblueline.org/satellite-tracking-sea-levels-set-launch
The UK Environment Agency -where possible like to use physical tide gauges as well when developing flood defence schemes, which are both visually observed or can send data electronically. Best of all is gathering information from local people such as the Harbour master or those who work the fishing boats and who know what is really happening.
Modern Sea level rises -where happening- are not being seen in context as another of those regular cycles that stretch back much further than the satellite records into the depths of recorded time.
As Ron mentions in his post Aviso makes use of a proxy to determine volume and adds in .3mm from satellite altimetry which has its own flaws.
Tony Brown
As opposed to the Gospel according to Luke Warmer:
I though sea change is caused by:
1. Earth’s core is cooling;
2. As earth’s core cools, it shrinks;
3. As core shrinks, the earth shrinks;
4. As the earth shrinks, the fixed amount of seawater has less area to cover, and thus the depth increases (following from V=l*w*h);
Thus, the only affect AGW should have on sea level change may be to slow thermal transfer from the hotter core, slow cooling, and thus, slow sea change- true?
The 1870-1993 graph is distinctly non-linear and seems to comprise a slow rate from 1870-1930 and faster rate from 1930 onwards. Can anyone check how similar the rate rise is from 1930-1993 to see how it compares to 1993+?
Re: Rob Spooner (#136),
Beyond the expected adjustments for satellite track and for quality control (atmospheric conditions measurement errors), they also make at least three other possible adjustments to the data.
Two were mentioned earlier in the the thread:
The GIA (glacial isostatic adjustment) is an increase in the trend of .3 mm/yr due to presumable a study which showed that the ocean basin volume was changing at that rate due to reshaping itself when the glacial ice melted thousands of years ago.
The IB (inverse barometer) adjustment supposedly takes into account that changes in atmospheric pressure can affect the sea level (by compressing the water?) so an adjustment is made to the same pressure.
The third one surprised me – there is a sizable seasonal variation in the global sea level. I didn’t see that on their website, and I am not sure what would cause it (unequal amounts of water in the northern and southern hemispheres?). I located the anonymous ftp directory at the AVISO site which contains the various time series in netcdf format. There are series for global and regional ocean basins as well as the various combinations of the adjustments and separate and combined series for the satellites.
For example, here is a plot of the combined satellite data, GIA and IB applied. The plot shows a comparison of the data with and without the seasonal adjustment:
I am not sure how the correction is actually made. Since the data is a sequence of measurements 10 days apart, it is not as simple as subtracting monthly averages. R has the ability to read the files so anyone wanting to play with them if they wish to figure it out. 😉
Re: RomanM (#144),
The GIA corrections would be worth looking into. For the GRACE satellite data, see the paper
“Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo”, Cazenave et al, Global and Planetary Change 65 (2009) 83–88.
I havent read the paper carefully but look at fig 1, which is quite striking – the raw data shows no change at all in ocean mass.
A figure of 2.1mm/yr arises purely from the ‘GIA correction’.
And how is the correction obtained? From modelling only, and the result depends on the modelling assumptions!
Meanwhile the AVISO page that Rob refers to lists 11 different corrections, most of which are obtained from models. Many of these corrections are huge – for example the ‘dry troposphere’ one is of the order of 2.3m !
Re: PaulM (#146),
What is more, the “Dry troposphere” correction seems to be based on model estimates, which brings the logic around to an irregular circlar shape.
Re: Geoff Sherrington (#149),
IIRC, the dry troposphere correction just assumes the dry adiabatic lapse rate. That’s pretty solid. It’s the wet troposphere correction that needs models as there just aren’t enough direct measurements of water vapor distribution.
Re: DeWitt Payne (#150),
I stand corrected. Sorry, just recovering from a big computer crash and thoughts not together yet.
Re: PaulM (#146),
So to summarize and clarify, you’re saying that the paper says that there’s no net increase in water in the oceans, and those graphs at NASA are showing the effects of rising ocean floor (and possibly thermal expansion of water)?
Re: Calvin Ball (#152),
That’s not quite what it says. GRACE measures local g which would be a function of not only the mass of water, but the mass of the rest of the Earth. If the sea floor moves down relative to the geoide, and we know it does but are somewhat uncertain how much and where, and nothing else changes local g decreases. There’s also the density difference between rock and water. The raw data showing no change in apparent mass is indeed consistent with an increase in sea level and ocean mass. Besides, GRACE also shows Greenland and Antarctica are losing mass and that water has to go somewhere.
Re: Calvin Ball (#152),
a couple thoughts on gravity…
The formerly ice-bound continents are rising. The ocean floor is lowering in response to the crustal movement. So as the ocean floor lowers GMSL lowers as well. The rising crustal mass also affects the regional gravitational field. If you are standing on a beach looking out at the beautiful sea, the rising continental crust at your back will have the effect of reducing the vertical component of g at that point in space you occupy. Also the lowering oceanic crust in front of you as well as the lowering mass of water will have the effect of reducing the vertical component of g at that point in space.
I confess to not having yet read the GRACE reports. If one takes the changes in g as calculated by the GRACE platform at face value, there is something causing a reduction in the vertical component of gravity over Antarctica and Greenland. Whether that reduction is due to lessening of the ice mass or movement or settling of the ice or crustal mass cannot be determined by the GRACE measurements alone.
FWIW, this is a pretty good summary of the method. That answered my questions of how it’s done.
Given that they seem to be able to produce, in more-or-less real time, a decent map of the ocean floor, and the sea surface, wouldn’t it actually make more sense to calculate total oceanic volume than trying to talk about sea level? It seems to me that the climatically significant number would be how much water is in the oceans. Or is the temperature data so sparse, that we can’t convert mass to volume accurately?
Re: Calvin Ball (#156), thanks, now I understand altimetry measurements a little better. However, the URL said “known tidal corrections are applied as well” but an icky bitty wind, and tide levels are seriously affected. How in Heaven’s name can one then presume to get trustable data?
What with Ecotretas, which I hope can be investigated further, I’m now beginning to wonder if we’ve got yet another major kerfuffle over the most basic data – or am I becoming a data alarmist?
Actually I don’t think so. John Daly has a brilliant collection of some 250+ global temperature records, nearly all rural, several very long, showing no real global temperature rise at all. Especially revealing is the record local to the childhood home of David Suzuki who claims – falsely, as the record shows – that the winter season has shortened (the cause has to be global warming).
Lucy,
Unfortunately, Blogspot doesn’t have PDF upload capabilities. I have the PDF file available through e-mail, please request it at ecotretas at gmail.com
If anyone is interested in discussing the underlying data, please don’t hesitate to contact me.
Ecotretas
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