As we surmised in earlier posts, the crozon.colorado.edu website was a test run. Here’s the newest graph from the revised http://sealevel.colorado.edu/
They write about the update:
Welcome to the new webpages from the University of Colorado sea level group! We apologize for the delay in updating our sea level releases, but the transition to these new web pages took longer than we thought. In addition, we have made many improvements to our data (new orbits, new tide model, new corrections) which ultimately had little effect on global mean sea level, but brought us up to date with the latest advances in the field.
One important change in these releases is that we are now adding a correction of 0.3 mm/year due to Glacial Isostatic Adjustment (GIA), so you may notice that the rate of sea level rise is now 0.3 mm/year higher than earlier releases. This is a correction to account for the fact that the global ocean basins are getting slightly larger over time as mantle material moves from under the oceans into previously glaciated regions on land. Simply subtract 0.3 mm/year if you prefer to not include the GIA correction.
You may also note that rate of sea level rise over recent years has been less than the long-term average. This is believed to be due to the recent La Nina’s we have been experiencing, though research on this is continuing. We will soon add a plot to the web site illustrating this effect.
Let us know if you spot any bugs in the new web pages. Thanks for your interest!
Comments welcome.
No, if CU is claiming to report “Sea Level” then they shouldn’t be adding a 0.3mm/year correction to their sea level graph.
It would be much more credible for CU to have another graph titled “Sea Volume” which adds the 0.3mm/year correction.
Interestingly, CU is now claiming that:
Sea Volume Rate of Increase = Sea Level Rate of Increase + 0.3mm/year.
Yet they are keeping the misleading title of “MSL” on this graph.
My question is, if Sea Volume stops increasing at all, does that still mean that Sea Level will be DECREASING by 0.3mm/year?
@ur momisugly ImranCan: re your last, thank you – I am glad to agree.
I think the “GIA Corrected note” under the upper left legend to be wholly inadequate. For instance, what GIA correction? Today it is 0.3 mm/yr for the past 15 years, Last month it was nothing. What will it be next year? So it is inexcusable not to be specific here about the amount and direction of the GIA correction.
CU should put the “With +0.3 mm/yr GIA Correction” immediately below the “Seasonal signals removed.” Note in the lower right.
What could be the objection to this extra bit of documentation? … Unless you prefer to hide the decline of the the rate.
TimC
I apologize for the collateral damage of my remark re impugning other commenters who have opposed the conversion of the sealevel series to a delta volume of ocean series – you are innocent of that.
AG Foster
I apologize for impugning your LOD specialty and I thank you for a very enlightening rundown on the significance of LOD and the factors that contribute to it. I suggest a full post on this interesting topic.
But you don’t get off scott-free! We shouldn’t have to extract a metric like msl from a halfway-to-ocean-volume-change metric especially when the name remains sealevel series. Also, knowing the MO of the alarmist, this new metric will ‘confirm’ that ocean levels are rising quicker than we thought. I would be happy to leave them with their delusions if they didn’t have the ear of our law makers and taxation pals. You are correct that a foot or so of water isn’t going to be catastrophic by 2100 but try googling agw or climate change and sea level rise and see what reasonable people are up against.
TimC says:
May 7, 2011 at 6:48 pm
@ur momisugly Catcracking: if you look at the CU site explanation for the GIA adjustment (URL below) you will see reference to papers from Peltier in 2002 and 2009 which I think identified the effect. Although GIA is very gradual on a yearly basis it amounts to 3cm/century which can’t just be ignored – it is a real effect on MSLs, recently identified, which has to be taken into account:
URL: http://sealevel.colorado.edu/content/what-glacial-isostatic-adjustment-gia-and-why-do-you-correct-it
Tim,
Obviously you miss my point that it is not a coincidence that they suddenly now incorporated a new correction factor to mislead people by to “hide the decline”. Why did they not apply it earlier?
As you point out they did not just learn about it yesterday, since the date of your referenced referenced papers on the subject is 2003 and 2007.
The MSM will conviently report the “corrected” numbers rather than the raw data to keep the fear of rising sea level on the table.
Catcracking: thanks, I take your point but isn’t it rather paranoid keep looking over our shoulders all the time, for fear of what others will say?
For me it’s more important to have data providing the most informative and useful insights into the natural world, wherever this takes us in the AGW debate. At some time all the controversy will be over – better sooner than later even if it turns out the sceptical position was more wrong than the warmist position (I think it will all be a matter of degree – pun partly intended!)
Re: Gary Pearse says:
May 9, 2011 at 11:45 am
I assure you I am no expert on the subject. For genuine expertise see Richard S. Gross in “Treatise on Geophysics,” vol. 3, 239-294: “Earth Rotation Variations–Long Period.” If you are affiliated with an institution this can be requested online at
http://www.elsevier.com/locate/permissionusematerial
And I have to agree with TimC–we’re making a mountain out of a molehill here. We certainly would insist on corrections for shoreline subsidence, so why not basin subsidence? But then I would have to agree, it could no longer be called “sea level data” –sea depth data, yes. But it never was “raw” data. As for timing, I don’t think they expect it to keep going down. It’s been rising for 7000 years, fairly steadily. This 10% correction is not in the same ballpark with claims of “tripling.” It is a step forward, however clumsy.
We need to be able to step back and forth across the divide between paranormal alarmist science and normal science, and to distinguish between the two. If the pseudoscience didn’t exist nobody would be complaining here, and the alarmists are not to be taken seriously in a discussion between serious scientists. –AGF
It’s equally important for the data to be given a name that ISN’T misleading.
Rename it!
I agree that they don’t expect it to keep going down.
But the idiots that made silly claims about future sea level rise probably didn’t take the increasing size of the basin into consideration. Those silly claims need some support in order to prevent embarrassment.
Utilizing this adjustment and continuing to call it sea “level” provides a bit of support.
It would be not only interesting but useful to compile a list of those who have made the unsubstantiated claims of sharp sea level rise. Time to google. –AGF
sealevel.colorado.edu does not respond this morning.
This has to be the single most stupid thing I have read all day.
“This is a correction to account for the fact that the global ocean basins are getting slightly larger over time as mantle material moves from under the oceans into previously glaciated regions on land.”
Does that not suggest, and it stands to reason, that as result of the basin getting bigger, water levels would necessarily decrease. Further, the expansion of the sea floor results in mountain building and an increase in land elevation. While keeping my comments basic to the statements, where am I wrong?
They are doing it the wrong way.
If the continents are rising the sea level rise is the satellite measurement minus(!) continental rise.
So the value that makes sense is to subtract the GIA from measured sea level, resulting in a 2.6 mm/year sea level rise which comes closer to the tide gauge sea level estimates.
As a geologist I don’t understand the statement “This is a correction to account for the fact that the global ocean basins are getting slightly larger over time as mantle material moves from under the oceans into previously glaciated regions on land.” Besides making my head hurt this statment doesn’t seem to make sense. If the ocean basins are getting bigger which is true because of plate spreading of the ocean ridges which produce mantle material, how does it move into previously glaciated regions on land. Somewhere there is an escalator that carries magma from the spreading ocean basins to the surface where previously glaciated areas once existed. Only in Boulder Colorado.
my bold. Note this is not just the sea level but the rate of change of sea level. Assuming what they have written is correct that is not a linear but a quadratic increase (an accelerating increase) in GMSL.
Well that would explain it. A quadratic increase in GMSL (volume proxy) would give a quadratic increase in total heat energy. This is exactly what would be the result of an exponential increase in CO2 ( ln(exp(CO2)) = linear forcing = quadratic rise in Temp ).
It’s hard to see how the mantle rebound could be acceleration 11000 years down the line. They have just written themselves a “CO2 fingerprint” into the data with this change.
It’s a small adjustment but every little helps. As the temp record starts to diverge from the CO2 trend , this will ease it back into line.