People send me stuff. Here we have another case of value added adjustments that increase the slope, much like temperature.
This email forwarded from Steve Case reads as follows:
The University of Colorado’s Sea Level Research Group just published the 2013 Release #1 of their Global Mean Sea Level Time Series.
![sl_ns_global[1]](http://wattsupwiththat.files.wordpress.com/2013/01/sl_ns_global1.png?quality=75)
I discovered that these periodic releases are on the net all the way back to 2011 Release #1. So I downloaded all nine of them.
2012 release #1 has 628 entries up to January of 2011 so I had Excel’s slope function calculate the rate of sea level rise for that time series of 628 entries across all nine releases.
What I found is that the rate of sea level rise has been bumped up twice since then, once in 2011 and the the latest in the current release. Here’s a link to a graph to illustrate the point:
![2vmenpv[1]](http://wattsupwiththat.files.wordpress.com/2013/01/2vmenpv1.gif)
http://oi45.tinypic.com/2vmenpv.jpg
Coupled with the GIA increase of 0.3 mm/yr that was made prior to these nine releases the rate of sea level rise has been bumped up 0.43 mm/yr in the last few years.
This sort of thing has been going on more or less regularly and it seems to go only one. way.
Here are the links to the data:
http://sealevel.colorado.edu/files/2011_rel1/sl_ns_global.txt
http://sealevel.colorado.edu/files/2011_rel2/sl_ns_global.txt
http://sealevel.colorado.edu/files/2011_rel3/sl_ns_global.txt
http://sealevel.colorado.edu/files/2011_rel4/sl_ns_global.txt
http://sealevel.colorado.edu/files/2012_rel1/sl_ns_global.txt
http://sealevel.colorado.edu/files/2012_rel2/sl_ns_global.txt
http://sealevel.colorado.edu/files/2012_rel3/sl_ns_global.txt
http://sealevel.colorado.edu/files/2012_rel4/sl_ns_global.txt
http://sealevel.colorado.edu/files/2013_rel1/sl_ns_global.txt
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Pat Moffitt says:
January 25, 2013 at 1:14 pm
Not to mention that the rate of rise has been essentially constant for a hundred years.
http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?stnid=8534720
Wow, I got a lot of answers to that! I’ll try and get round to some of the points.
M Simon, that level of time measurement should not be a problem. The best atomic clocks are accurate to within something like 0.01 ns per day, and DEMs regularly report precision of well less than a centimetre. My field experience with (much cheaper) terrestrial lidar doesn’t give me any reason to doubt this.
M Simon & Gail Combs; you question whether the statistics of the errors I used are appropriate because the thing changes. I think they are as we’re considering the average sea level height here.
The errors are affected by wave height etc, but that seems to be included in the error budget. The absolute value of sea level at each point isn’t relevant, only the error. The measurement error is typically independent for each sampling, so these are the correct stats to use assuming normal distribution of errors, which I didn’t check. Even if it differs from Gaussian, it would have to be pretty extreme to change my estimate by the two+ orders of magnitude suggested by some on here.
It’s fun to accuse scientists of fraud/stupidity/confirmation bias, but until I see the evidence before me showing that the peer reviewed work on sea level estimation from satellites is grossly wrong then I’m not buying it.
The best atomic clocks are accurate to within something like 0.01 ns per day, and DEMs regularly report precision of well less than a centimetre. My field experience with (much cheaper) terrestrial lidar doesn’t give me any reason to doubt this.
Yes. On the ground. In space? Doubtful. And it is not the accuracy of the clocks I’m questioning. It is their resolution. And the 10 pS per day you mention is not measured. It is computed. What is the RMS noise? It could be as bad as 1 ns for a given measurement although several 100s of ps variation is more likely.
So you have a noisy measurement of 60,000 different samples per day of ocean height. Now just exactly where was the zero crossing? How accurately are the tides accounted for? There are a LOT of things that can confound that height measurement.
My understanding is that it takes 10 years to see a significant difference in height at the current rate of rise.
Making accurate measurements of time is not easy. I discuss this every day on a list.
M Simon & Gail Combs; you question whether the statistics of the errors I used are appropriate because the thing changes. I think they are as we’re considering the average sea level height here.
You don’t measure an average. You compute it.
Doug Proctor says: January 25, 2013 at 3:34 pm
” ….Remember the 21 “high-quality” tidal guages that were used a few years ago to estimate a much slower rate of rise? I wonder that those 21 show …..”
About 2 mm/year over 100 years, including the 0.3 mm/year GIA adjustment.
The original 24 sites were published as Douglas etal 1997, but it does not seem to be available anywhere … here those24 sites are plotted up to about 2005 on shown on Wikipedia …
http://en.wikipedia.org/wiki/File:Recent_Sea_Level_Rise.png
Sorry – mathematical errors below … about 27.5 cm over 200 years (NOT 100 years) = 1.4 mm/year … including 0.3 GIA … so real rise is more like 1.1 mm/year……
Doug Proctor says: January 25, 2013 at 3:34 pm
” ….Remember the 21 “high-quality” tidal gauges that were used a few years ago to estimate a much slower rate of rise? I wonder that those 21 show …..”
About 2 mm/year over 100 years, including the 0.3 mm/year GIA adjustment.
The original 24 sites were published as Douglas etal 1997, but it does not seem to be available anywhere … here those24 sites are plotted up to about 2005 on shown on Wikipedia …
http://en.wikipedia.org/wiki/File:Recent_Sea_Level_Rise.png
Re Doug Proctor says: January 25, 2013 at 3:34 pm and markx says: January 27, 2013 at 6:52 am
Sea level rise acceleration was covered in WUWT in July 2011 (The battle over sea level in JCR | Watts Up With That?) and again in May of last year:
http://wattsupwiththat.com/2012/05/16/is-sea-level-rise-accelerating/
Two references using tide gauge measurements:
Is There Evidence Yet of Acceleration in Mean Sea Level Rise around Mainland Australia? P. J. Watson
http://www.jcronline.org/doi/abs/10.2112/JCOASTRES-D-10-00141.1
and
Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses J.R. Houston{ and R.G. Dean
http://www.jcronline.org/doi/pdf/10.2112/JCOASTRES-D-10-00157.1
MieScatter says:
January 25, 2013 at 3:26 am
Your assumptions are wrong! There is only one measurement a day taken at any given location!
Model away but you can’t eradicate that 11cm potential error.
DaveE.
Dodgy Geezer said:
_____________________________
January 25, 2013 at 1:29 am
…and has anyone asked the University of Colorado for an explanation…?
_____________________________
Yes I did. A while back I asked about the +0.4 mm/.yr variation between their 2004 Release #1 that you can find on the internet wayback machine and that same 1993 – 2004 time series in the current release. I got an answer back that said that they “… cannot point to any specific update that is the main cause of the differences between the 2004 and the current release. But a partial list of the more influential updates include:
– updated orbits
– updated radiometer corrections
– updated tide models
– updated sea state bias models
– updated dynamic atmosphere
A review of the release notes (http://sealevel.colorado.edu/content/release-notes) shows how we continually apply what the altimeter science community considers to be the most up-to-date set of processing parameters. In fact, the Jason-2 data is currently being re-released and updated to the GDR-D standard, and this will most likely affect the altimeter time series due to these improvements.”
Well what did I expect them to say?
It’s obvious that adjustments have been made and that UNFCCC(politics) is to blame?
who is Steve Case?
nobody knows Steve Case?
markx wrote on January 27, 2013 at 6:52 am, “…= 1.4 mm/year … including 0.3 GIA … so real rise is more like 1.1 mm/year”
That 1.1 mm/year rate of sea-level rise is exactly what I calcuated as both the median and the geographically-weighted average of the sea-level trends at 159 NOAA-selected GLOSS-LTT tide gauges (average record duration of ~85 years).
Dave Burton
webmaster, sealevel.info
Anthony, you really should se my Joanne Nova – article on this topic:
http://joannenova.com.au/2012/05/man-made-sea-level-rises-are-due-to-global-adjustments/
K.R. Frank
NOAA Climate Program Office released “Global Sea Level Rise Scenarios for the United States National Climate Assessment” in December 2012:
http://www.cpo.noaa.gov/Home/Home/AllNews/TabId/315/ArtMID/668/ArticleID/80/Global-Sea-Level-Rise-Scenarios-for-the-United-States-National-Climate-Assessment.aspx
Summary:
“Published December 6, 2012
“Global sea level rise has been a persistent trend for decades. It is expected to continue beyond the end of this century, which will cause significant impacts in the United States. Scientists have very high confidence (greater than 90% chance) that global mean sea level will rise at least 8 inches (0.2 meter) and no more than 6.6 feet (2.0 meters) by 2100.”
[End quote]
Table ES-1 provides the range of the four scenarios of global sea level rise by 2100, from 0.2 m (0.7 ft) to 2.0 m (6.6 ft). From Figure ES-1, the lowest scenario is an extrapolation of measured sea level rise. The other three scenarios presume varying degrees of acceleration of sea level rise assumed to have begin in 1992. The calculated rate for the lowest scenario would be 200 mm in 108 years, or about 1.9 mm per year.