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.
@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
@ur momisugly Mike Jonas: the NASA eclipse web pages (URL below) give estimates for ΔT (the difference between Terrestrial Dynamical Time – broadly time based on the earth’s position in its orbit round the sun – and Universal Time – based on the earth’s daily rotation about the NS polar axis) from 500 BCE to date, which I think can show the estimated changes in LOD and the standard error for the historical records.
URL: http://eclipse.gsfc.nasa.gov/SEcat5/deltat.html
Sea level scientists don’t want to leave all the cheating, adjusting and lying to climatologists. Scientific race to the bottom. Fire them all.
On the Sea Level Reference Page, I suggest adding the following sub-heading to this graph:
NB! As of May 5th 2011, this graph no longer represents actual sea level rise.
A G Foster and TimC – thanks for your replies. I should have done more thinking and reading first!
About GIA : Have I got this one stuffed up too? The Colorado Uni web page says “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.“. So the GIA adjustment doesn’t relate to actual sea level at all – it is explicitly a sea level increase which has not happened. So there are no circumstances in which adding in the GIA adjustment is meaningful for sea level. All uses of the Colorado Uni sea level data should always therefore first deduct 0.3mm p.a.
“Correcting” for sea level rise is such a crock! It’s obvious they don’t want people to look at the chart an conclude there is not problem. If they present a chart that purports to depict sea level rise, it should be that and only that. If they want to then present a second chart corrected for what they think they know, fine, but don’t mess with the chart of the primary measurement. These people should be fired.
@TimC : What is it about the definition of sea level RISE that you don’t understand???
The “scientists” involved in this have zero integrity and we taxpayers should stop paying them for this crap.
Something fishy about the LOD stuff, too. If ice melts from high elevation and flows into the sea, raising the sea level, how can anybody say lengthens the day? That water is getting closer to the center of mass, which would speed the rotation, not slow it. And, if magma flows under formerly glacier covered land, raising the land level, didn’t it have to flow from somewhere else, lowering the level where it came from? Maybe liquid rock is a lot more compressible than I’m giving it credit for being? Why does every imaginable natural phenomenon trend in the favor of warmists or else the data has to be massaged until it does?
@A G Foster says:
May 6, 2011 at 1:49 pm
Look, the problem is to figure out whether the mass of the ocean is changing. To know this you have to keep track of sea level, and you have to know if it’s warming and if the basins are changing.
We can’t measure all that stuff. The whole point of looking at sea level is get some idea of all that other stuff. Now, when sea level doesn’t do what the theory says it should do, the “scientists” are going about adjusting the data to fit the theory. No matter how you spin it, that is what they’re doing.
The bottom line is that if you live at a coastal area, there is no evidence that you have anything to worry about from climate change. It hasn’t made much difference to sea level rate of change.
@jim: excuse me?
Sea levels are rising according to all the satellite altimetry measurements, compared with measurements as at past dates.
The ocean basins are also getting bigger according to the recent GIA analysis. This has the effect of slightly reducing the sea levels.
If you would rather take actual rises, net of the GIA reductions, just reduce the figures by 0.3 mm/year as CU suggest.
If you would rather focus on interesting data such as the total volume of water in the oceans (to get a handle on whether the net amount of water running off icesheets and glaciers is increasing due to higher global temperatures, or staying pretty much constant) you have to add the GIA adjustment, as CU are now doing, to get the true level of rise due (principally) to increases in the volume of water in the basins – ie. the water run-off from land-based ice.
Clear now?
@TimC
Indeed if you want to measure the volume of water then you need to take out such factors as the size of the bucket. But the volume of water is not what is of interest – it is the sea LEVEL ! Which is why the name of the academic group publishing this is : Sea Level Research Group, University of Colorado. So the size of the bucket is extremely important. There are many many factors which affect sea level – they could also take of such factors as sedimentation input, or basin subsidence. Why not throw out mid ocean ridge spreading as well ?? Or rock lost to subduction. The point is that its not correct to just throw out those factors which are inconvenient because they might be causing sea level to drop. If you want to be measuring global sea level then you need to be measuring global sea level – not some artificial number representing something else.
And referring to your other post : its not magma which is “flowing around” in the mantle. Magma is molten rock. The mantle is solid, not liquid.
Not satisfied with the responses to my Qs:
“What is the academic mainstream rationale for assuming constant GIA?”
“What’s the academic mainstream rationale for assuming constant GIA?”
Anyone able to succinctly answer the Q as posed?
@ur momisugly ImranCan: This is just down to clear labelling. The CU graph doesn’t actually plot absolute sea levels: it plots ΔMSL (mm) on the Y axis against time. ΔMSL is change in sea level as from an arbitrary datum (the individual satellite’s altimeter reading at a given time/date) – I don’t think these are absolute figures, all referenced to a “standard” height on the geoid.
All that’s needed is clear labelling, so everyone understands precisely what is being plotted. The WUWT reference pages now make it crystal clear that CU’s graph includes this GIA adjustment; if you think the CU web page itself does not make this clear you will have to take it up with them!
And yes, the magma is indeed the molten rock under the mantle – but it very slowly flows according to relative pressures on the mantle such as from a mile’s depth of water or (lack of) a mile’s depth of ice.
@ur momisuglyPaul Vaughan: I really think you should raise this with CU, if the papers mentioned in the GIA FAQ on their website don’t give you the answer.
P. Solar, I’ve just taken a look at interannual GMSL’ & GMSL”. You’ve got a serious leverage problem in your trend lines because of seasonal components. For each difference you take, you need to integrate over dominant modes. Bear in mind that the further y-outliers are from the x-mean, the worse the leverage problem. Your seasonal components are introducing a leverage problem in the worst possible place – i.e. at the extremes. I recommend trading your gaussian filters for repeat 1 year moving averages for starters. (The dominant temporal mode of terrestrial variations is KNOWN, so gaussian isn’t the best option.) You’ll need 1 application on the raw (non-anomaly) data and then n additional applications for the nth derivative. See Maraun & Kurths (2005) section 3 for more. Sometimes repeat 6 month smoothing is also needed; it depends on the nature of the series (i.e. on whether there’s a semi-annual component).
Are we to believe it is sensible to assume GIA has no seasonal component? No interannual component? Whenever time & resources permit, this is going to be a very tedious audit to undertake.
TimC & Foster
Your view of this matter is clear – it is useful to know what the changes in ocean vol are and you are happy to learn that the bucket changes +0.3*A of ocean in mm^2. Surely you are aware, though that the issue of d msl has been entirely about inundation of low-lying countries and regions and the catastrophe to be wrought.
To cripple real and useful data to morph it into some completely different and less useful metric has got to be viewed with great scepticism, especially when the higher numbers obtained will then be illegitimately used for the same purpose (watch and see if I am wrong). How are you going to handle the Maldives being under a metre of virtual seawater and yet remain high and dry – why should a country, harbour engineer or navigator have to subtract a factor added on to the sea level series to find out how much actual water they’re dealing with. You had the hubris to say that only a few commenters showed that they understood the issue. Indeed, you showed yoirself to be acquainted with the smaller egghead issue that allowed you to add value to your smaller specialty of LOD. The commenters you impugn rightly understand the larger issue here.
@ur momisugly Gary Pearse: thank you for that, but on your “hubris” remark I would be grateful if you would clarify where I have ever said in any comment under this Article – or at all – that “only a few commenters … understood the issue”. I’m not aware of ever having made such a comment.
There has been a very straightforward change in CU’s method. Instead of plotting ΔMSL, CU are now plotting ΔMSL + 0.3*y, where y is the number of years (or part years) elapsed to the time the data is taken. Anyone can easily reverse out this adjustment. I personally think this is a sensible and helpful step to adjust for GIA. CU obviously think so too, otherwise they wouldn’t have made the change. The change, and reasons for making it, are properly documented on CU’s website.
If you are uncomfortable with CU’s new method I can only suggest that you approach the CU people direct. It’s not in my power to change CU’s methods nor do I want to – as I said in my first comment under this Article I just can’t see what all the fuss is about.
Re. Gary Pearse at 1:23:
No rational person can ever make a catastrophe out of a sea level rise of 30cm/century. The only way Hansen could make any case at all was by claiming a tipping point for Greenland–if melting hits a certain point the ice basin could collapse, leading to melting unprecedented in the last 100,000 years. But posters here have aptly pointed out on other 0ccasions that during much warmer periods that never happened. I’ve spend some effort in other arenas showing what a farce the Bangladeshi sea threat is: land subsidence due to millions of tube wells is orders of magnitude greater than sea level rise. Sedimentation due to supposedly increased Himalayan melting is also on the rise, and seemingly quite able to keep up with current and future sea level rise. Beach formation continues to be reported on the Ganges Delta. Yes, the threat of sea level is a complete farce–none of us said otherwise. I’ve countered anthropologists who claimed Eskimo villages were being inundated, noting that low lying Pacific islands are usually the more recently populated–they are periodically annihilated, and it has always been like that. They couldn’t care less between 10 meter waves whether the sea has gone up or down a foot in the last century.
But that doesn’t mean that every effort should not be made to accurately gauge the true ice/water balance on the planet, and I applaud CU for its efforts to do just that. So here’s the skinny on LOD and GIA. Over a century ago Assyrian tablets were deciphered which showed eclipses occurring two hours off what would be expected, so astronomers compiled data from these, Chinese and Greek sources to determine the rate of the earth’s rotational deceleration. George Darwin, son of Charles, calculated that the earth and moon separated two and a half billion years ago. This deceleration was attributed to tidal friction: a constant tidal bulge lags and drags 2 hours behind the maximum tidal pull.
With the first primitive satellite telemetry it was discovered that the earth is shaped like a pear, and the flat top was attributed to the fact that the globe was still recovering from the last ice age. Then mirrors were put on the moon and laser ranging produced the rate of lunar recession. The comparative contributions of lunar and solar tides are easily calculated, and the loss of terrestrial angular momentum to the moon could be determined by the lunar laser ranging (LLR).
Atomic clocks were put into action back in the 50’s, when LOD was determined mainly by stars crossing a telescopic view, and LOD could be studied with new precision, and compared with what LLR showed showed was due to tides (2.3ms/century). LOD increase calculated from ancient eclipses was only 1.7ms/century. The difference was attributed to GIA, .6ms/century.
But since the invention of atomic clocks no such deceleration has been detected–rotation has been up and down but stable on average (google “leap second” in Wikipedia). This presents a considerable problem for proponents of dangerous melting, since after all, melting is what sets the globe up for the following rebound. Just as the globe speeds up due to rebound, it slows down due to melting, and all this happens because the mantel is part elastic and part plastic. That is, there is instanteous GIA due to loading and there is slow, inelastic GIA, still going on 7000 years after the ice disappeared. The .6ms/century is a fairly reliable estimate of LOD change due to GIA. But the current acceleration is possibly due to GIA from the LIA, or heavy snow in Antarctica, or both.
At any rate, far from advancing the cause of the alarmists, LOD is a serious problem that most alarmists don’t know anything about. Just like they don’t know anything about Capt. Cook’s hundred foot pack ice. We skeptics like to think we are smarter than the warmists, so it’s somewhat dismaying to see legitimate science condemned as warmist propaganda–it hardly helps our cause. –AGF
TimC – Colorado Uni are supposedly giving us sea level data. The data is called “Global Mean Sea Level Time Series”, “Raw Data”. If I want the sea level, I now have to take 0.3mm p.a. off their data, because the data is not raw, it has been adjusted by something which is explicitly not part of the actual sea level. There are no circumstances in which I can obtain a sea level without taking 0.3mm p.a. off their data. How stupid is that?
@TimC
I am not sure how to say this more clearly.
1) If they are removing factors like ‘basin size’ then they are no longer reporting sea level (whether it is a delta or an absolute). They are reporting something else. I have taken it up directly with CU.
2)The mantle is not molten. There is NO magma flowing around and making basins bigger. What is ‘flowing’ is mantle rock – at that temerature and pressure it behaves like a plastic and has rheological properties that allow it to flow. At surface the rocks name is peridotite and it is mostly composed of magnesium and iron minerals like olivine and pyroxene. Magma (which you keep referring to) is what comes out of volcanoes or mid ocean ridges is created via different processes such as mantle upwelling which causes decompression resulting in partial melts – that is liquid magma.
You can’t just ‘wing’ these terms and bandy thenm around without displaying ignorance. Sea level is sea level (and not volume) and the mantle is the mantle (and not magma).
@ur momisugly Mike Jonas: (a) if you look at CU’s release notes, two paragraphs down from their “Raw data” hyperlink, you will see they already make adjustments to the data far more complex than just adding +0.3*y; (b) “Global Mean Sea Level Time Series (seasonal signals removed)” is (in my view anyway) still perfectly descriptive; (c) on an earlier point, governments of counties at risk of inundation (who can’t afford to employ sharp-eyed scientists to read release notes) actually have more time to play with before they are inundated than might first appear because of the adjustment; (d) the adjustment is anyway only 3cm per century – not exactly a huge figure and (e) it’s really no use banging on at me, you have to make your point to the CU people, or get over it.
@ur momisugly ImranCan: Free dictionary definition for magma: “the molten rock material under the earth’s crust from which igneous rock is formed by cooling”. Isn’t it this that flows, because it’s molten?
@Tim O'Donovan C
There is always a danger when one uses Websters as a basis for proclaiming scientific knowledge.
The mantle is not liquid. It is a viscous solid. And there is not a pool of magma which is flowing around down there. Magma is a very specific product of partial melt of mantle material caused under specific circumstances upwelling at eg. mid ocean ridges and/ or mantle plumes (like under Hawaii). It is true that magma originates from mantle rock, but it is not present generally.
@ur momisugly ImranCan: what I actually said to another contributor (substituting the definition, for clarity): “the earth isn’t expanding: [the molten rock material under the earth’s crust] is just slowly flowing away from the ocean basins (which are therefore dropping) into the formerly glaciated land areas no longer bearing the weight of all that ice, which are rising. It’s rather like squeezing a toothpaste tube with the cap on – the total volume is unchanged.”
We don’t have to be PhDs to comment here, and I didn’t assume I was addressing one (I have a science masters from long ago but my actual career is in law). Without all the abstruse technical details, I think my comment above adequately described the processes at play.
They are really screwing with the data to make it go their way….
http://theinconvenientskeptic.com/2011/05/sea-level-update-more-upward-revision-found/
@TimC
“Without all the abstruse technical details, I think my comment above adequately described the processes at play.”
Other than the fact that the mantle is NOT molten, you are spot on.