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.
they always correct upwards don’t they
Interesting stuff. Wonder why they only plotted the three first weeks of January?
And this basin stuff is just unbelievable! Someday, they will be adding even more mm rise, for the water that is presently in dams, and should be at sea…
Ecotretas
The trend since early 2002, when the Jason satellites came into play, is only 2.3 mm/yr. Without all the convenient adjustments it is lower still.
Even though the actual sea level is what they purport to measure, they decide to add a small positive adjustment every year for the fact that some parts of the land are rising due to rebounding from the last ice age. Measurements are measurements where I come from, & if my local tide guage showed a rise of 2.7mm a year because the land is rising by 0.3mm, than that must be the true reading. Do they also adjust for the fact that any rising land areas are also increasing the sea-level rise in those areas which are not rising? I can’t see how this adjustement is anything other than an artifice to satisfy the CAGW believers.
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.
Sorry, they lost me with adding then subtracting, then saying it didn’t matter and I could use the previous reading without the addition?
And still researching La Nina?
My head hurts.
The GIA seems irrelevant to me. As I understand it, sea level is measured in reference to land. If they were reporting on sea volume, then I could see making a case for that. At least they added the caveat that we can ignore the GIA if we want to.
So we are no longer measuring actual sea level but adjusted values bases on assumptions. The actual levels are what we want not ( well the sea is actually rising more than actually measured because of xyz so its worse than we thought).
As far as La Nina causing a drop in sea level, surely this is spurious. An upwelling of cold water is not cooling the ocean overall. In fact because the surface is colder the ocean would be losing less energy overall in those cooler areas compared to energy absorbed from the sun. There would be a drop in sea level locally but this would be reflected by a rise elsewhere.
“we have made many improvements to our data (new orbits, new tide model, new corrections)….”
Models are data now? Really?
How do you ‘improve’ data? Data is a recorded physical measurement of some characteristic. Any adjustment to the data, without retaining and disclosing the original data, invalidates it.
“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. ”
Aren’t these same global ocean basins also subject to siltation inflows from river deltas, wind blown dust from desert regions , volcanic eruptions and lava flows directly into the oceans, and even in-falling debris from space? Are these also factored into their ‘global ocean basin models’? All of these natural effects contribute to naturally rising sea levels by making the basins slightly smaller. They should be subtracted from the overall trend.
And do they also play off against each other the movements of the various tectonic plates? Eg India is pushing into Asia, which enlarges the Indian Ocean, but Africa is tearing itself apart, which diminishes the same ocean. They might also want to take into account the rise & fall of various plates as a result of earthquakes. The more you think about it, the more complicated a simple idea like sea level becomes.
Aha! So the deepening of the basins is creating a 0.3mm increase? Or zero apparent increase is now actually 0.3mm/yr?
Whatta crock.
Huh, the new data’s knocked the average rate-rise down from 3.4 to 3.1 mm/year i see.
I wish i could still find their data of the tidal gauge and satellitte data together. they used to have it all on one graph, it ws a great resource- but i haven’t been able to find it for ages.
Isotasy to the rescue (of rising sea level)! It is now rising the thickness of an ink line faster than before because of….ice that already melted. A new tide model? Does that change how the Bay of Fundy’s tides work?
Regardless, at 31 mm/decade, it’s not rising like Some WTWT catastrophists would have us believe…so why do they keep screaming that it is?
Methinks putting in the GIA is a little naughty if the principal metric of practical significance is the actual rise in sea level compared to levels on land. Of course, if we’re interested in oceanic volume, then that’s another story.
“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), ”
How was this calculated given the extent of the glaciations, the total land mass and the area and volume of the oceans?
How was this 0.3 mm/year able to calculated and added to the overall calculation without affecting the prior uncertainty +/- 0.4 mm/year?
It does not seem possible to calculate the affect of isostatic rebound on the global average sea level to 0.3 mm/year with +/- 0.00 mm/year uncertainty.
I don’t buy it. It looks like they added a constant so that the rate did not change.
3.1 mm/year +/- 0.4 mm/year.
“Simply subtract 0.3 mm/year if you prefer to not include the GIA correction.”
It is not a ‘correction’ it is a Constant Value added to have the data match the previously specified trend line.
Does anyone believe that by co-incidence adding the ‘GIA correction’ results in Exactly the same 3.1 mm/year +/- 0.4 mm/year that we saw in 2010_rel4?
I don’t buy it, it smells bad.
“the global ocean basins are getting slightly larger over time as mantle material moves from under the oceans into previously glaciated regions on land”
OK, how does that work? (Honest question, not my usual sarcasm).
“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”
So La Nina has been hard at it, unsuspected, since 2008?
(Sorry, sarcasm back on again…….must try harder…….)
So down from 3.2mm/yr to 2.9 if you don’t count their latest ‘adjustment.’ With any luck we may stay below even the adjusted line for a few decades if the apparent cycle in Tokyoboy’s Japan tide chart is real and worldwide.
From http://sealevel.jpl.nasa.gov/technology/
From its vantage point 1336 kilometers (830 miles) above the Earth, the US/European Jason-1 and OSTM/Jason-2 ocean altimeter satellites measure the height of the ocean surface directly underneath the satellite with an accuracy of 4-5 centimeters (better than 2 inches).
n.b. centimetres not millimetres 🙂
throw in an unsubstantiated positive 5mm fiddle factor over the period of the graph. Cross calibrate with previous satellite to maintain the positive trend (c.f Mann, trees and real life) and admit that the surface of the earth moves as in the case of Japan’s 8 foot coastline shift earlier this year
and then be amazed that your latest measurements show a decrease you cannot explain
A 5 cm increase over 17 years measured by 3 different instruments accurate to 5cm from a height of 830 miles
I’m scared we are all going to drown :-S
:-))
Dave
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),
Translation: “We believe that the recent fall in sea level will decrease the apparent rate of rise by 0.3 mm/year, so we’ve adjusted this out.”
Bug shmug.
So, if we don’t like the GIA correction, just remove it.
How about they don’t include the GIA correction and tell people if
they want to increase the rate of GMSL…
wait, oh yeah, that would be double dippin…. my bad.
/sarc
They’ve dropped Envisat from the record. Without explanation.
Here’s their data which I saved from the old Colorado website:
http://members.westnet.com.au/jonas1/ColoradoUniArchivedData.txt
I have very quickly graphed the old and new data, and I have not checked it carefully!!!
Graph of old data:
http://members.westnet.com.au/jonas1/ColoradoUniOldData.jpg
Graph of new data:
http://members.westnet.com.au/jonas1/ColoradoUniNewData.jpg
Graph of the differences:
http://members.westnet.com.au/jonas1/ColoradoUniDiff.jpg
Interesting.
By my calcs, the overall trend in the new data is less than in the old data, even though they say they have added 0.3mm p.a.
Also, there is a clear downturn in the data in recent years. They say “La Ninas”, I say PDO cooling phase.
In haste …..
What’s all the fuss? If the ocean basins are getting larger due to GIA then there should be some adjustment so that the decadal/centennial data is self-consistent. And it’s not the fact that sea levels are rising that’s important, but rather the 2nd order differential – any acceleration or deceleration in the rate of rise – that’s crucial.
If it’s feasible to reverse out thermal expansion effects due to ENSO, PDO, AMO et al that’s even better – this will eventually give true self-consistent altimetry data on decadal/centennial timeframes so we can then see whether there is any substance at all in this CAGW scare.
The only really important issue is that all adjustments to the data are properly documented.
Since I had last archived raw data (in 2010.6057) several new cycles appear in this data, that were not available before:
2004.1173
2006.8864
2008.6782
2008.7325
2008.814
2009.0311
Ecotretas
vaporware.
So the rate over the last 19 years is 3.1mm/year. That comes out at 310mm/century.
In old money that is 12.2 inches.
OVER A FOOT! IT’S WORSE THAN WE THOUGHT!