The MSM is usually several days behind the blogs on issues regarding data quality. In this case, I don’t recall reading about it on the main climate blogs, missing it isn’t impossible with my current schedule.
Fox news covered this. As we all know Fox does not deliver real news and only liberal outlets like CNN, MSNBC, NBC, BBC, CBS, etc., etc… can be trusted for ‘real’ news. So please take that into consideration. It appears that the Heartland institute may have initially uncovered the story but Sea level data published by peer reviewed scientists has a tweak in the numbers which requires a head scratching.
The University of Colorado’s Sea Level Research Groupdecided in May to add 0.3 millimeters — or about the thickness of a fingernail — every year to its actual measurements of sea levels, sparking criticism from experts who called it an attempt to exaggerate the effects of global warming.
“We have to account for the fact that the ocean basins are actually getting slightly bigger… water volume is expanding,” he said, a phenomenon they call glacial isostatic adjustment (GIA).
The above quote is in reference to the following:
Steve Nerem, the director of the widely relied-upon research center, told FoxNews.com that his group added the 0.3 millimeters per yearto the actual sea level measurements because land masses, still rebounding from the ice age, are rising and increasing the amount of water that oceans can hold.
So what they are saying is that they are correcting sea level rise for the lack of sea level rise due to increased ocean capacity created by nature.
So to sum it up, the sea level didn’t actually ‘rise’ that much, but it would have, we think, if nature would stop messing with the planet?
Well 0.3mm/year is tiny for sure right
But Taylor said that the correction seemed bigger when compared with actual sea level increases.
“We’ve seen only 7 inches of sea level rise in the past century and it hasn’t sped up this century. Compared to that, this would add nearly 20 percent to the sea level rise. That’s not insignificant,” he told FoxNews.com.
Hmm, a 20 percent increase in sea level rise because we don’t like that nature is messing with the actual sea level rise.
I have to say, if this is true, someone’s thumb is again on the scale.
Of course we all know climate scientists have “nothing to gain” from exaggeration.
the Air Vent 
The Glacial Isostatic Adjustment is discussed on this FAQ.
The philosophy of the SLRG seems to be that they want to measure the climatic changes of heat and ice melt etc. on the expansion of the volume of water, not the actual level. The problem with this is that what most people look at sea level for is to find out if and when they can expect their beach house to be inundated. But the Global Mean Sea Level (GMSL) is not the right place to look for that anyway! If people want information on that they need tide gauges. The problem with that is that the local trends can mislead people into believing warming is causing large changes, when in fact it is the local effects of subsidence and uplift that cause that.
Wait a minute; do I have this right, the land is rising so they have to give a numeric boost to the sea level so it can keep up?
Will the ocean have terran envy if it is not given affirmative action?
But, isn’t ‘inundation’ supposed to be the big threat?
I wish I was smart like those science guys…
RR
There actually is some justification for including a 0.3mm/yr adjustment if one is trying to close the budget on sea level by combining volume expansion from heat gain plus added water from icecap melt, plus mined fossil water, minus impounded water in reservoirs. In that case, we are actually trying to determine the change in volume and the glacial isostatic rebound correction makes sense.
Another point often overlooked in discussion of sea level is that the local changes in ground level are often of the same magnitude or even greater than any sea level changes. It’s kind of like the day to day variations in weather far outweighing any variations caused by climate change. To see the climate change variations, one must average over both areas and time. To see a global sea level change, one must average globally, otherwise things like ENSO, changes in currents, changes in distribution of persistent high and low pressures, and changes in local land level dominate what is seen.
Jeff
Glacial isostatic adjustment (GIA).is a geological phenomenon well enough known for quite a long time now. Basically it is used here to describe an increase in the volumetric capacity of the ocean basins due to continental “rebound” from glacial retreat as isostatic reaction to the last major ice Epoch continues. As a simple analogy: the bowl has become wider (deeper) because its’ sides are rising
The sleight of hand involved in the Sea Level Research Group report is twofold: 1) the actual extent of GIA is subject to much discussion over the accuracy of the metric; 2) the explicit alarm in the comment that if GIA was not happening, sea level rise would be bigger
Obviously, 2) above is the slickest of the assumptions (ie.if we ignore a fact, then the situation is worse than we thought)
I wonder what other adjustments are done that we don’t get told about ????????
Why does the AGW fanatical version of me spit upon thee, or worse?
FOX NEWS!!!
Evil incarnate.
You do NOT belong to our group.
That much I know.
And global warming creates snow.
And black is green:
Nick,
I have not previously encountered this adjustment, had you?
Jeff #8,
No, and the FAQ says:
“Prior to release 2011_rel1, we did not account for GIA in estimates of the global mean sea level rate,”
That release is just out, and this FAQ accompanies it.
I think the reason that it wasn’t an issue before is that it is pretty tiny, and the ability to measure 300 microns per year is recent. Then you really do have to work out what your datum is. Everything is on the move. In terms of total Earth mass, the lanfd is rising, and the centre of gravity of the sea is falling.
GMSL is currently mainly used as a proxy for ocean volume, and for that use, the GIA is the right thing to do.
And Margaret #6, you don’t have to wonder. That site lists changes as they occur – just read it.
” GMSL is currently mainly used as a proxy for ocean volume, and for that use, the GIA is the right thing to do.”
I don’t think that explains the advertisement of the data as sea level. Certainly few politicians are aware of the 20% extra. “Sea level” rise is fairly specific.
Dunno really if this is as crooked as it looks, but it don’t look good.
Jeff #10,
““Sea level” rise is fairly specific. “
Well, is it? What datum (reference level) do you think it implies?
Must have been a real lot of ‘racket ball-style’ glacial rebound by the Australian continent through most of the Holocene:
http://eprints.jcu.edu.au/1855/
I’m going over to Boston Harbor at low tide in the morning to check this out and catch a few stripers. It’s got to be in the morning because high tide tomorrow is just shy of ten feet. Makes it tough to stay dry while wading. I’ll report back if the fish are bothered by the extra 0.3 mm.
Well counselor, many would suppose that sea level rise is in relation to something. Land perhaps. However, if our pre-conceptions are unjustified, maybe the back of a sea turtle should be the datum.
😉
Jeff #14,
Yes, but which land. I think most people realise that (currently small) GMSL rise doesn’t translate well to your local beach, because local land ups and downs are often faster. They probably were using something like “global mean land level”. But that’s already hard to explain to the public, even if measurable by satellite.
Jeff – “Well counselor, many would suppose that sea level rise is in relation to something. ”
There you go again, grasshopper, assuming the definitions in Climate Science. You must wait until you are told what it is.
“But when will I be told master?”
It will be revealed when the time is right. And it is then that you will truly know.
What’s behind the green door?
===========
http://www.john-daly.com/
The Isle of the Dead is apparently an example of land rising in perfect unison with the sea for over 150 years!! Ain’t nature amazing Nick??
OK, now there’s a response from CU.
Good to see ‘doctor the sea level data’ in print and in that publication, Nick. Appropriate skepticism now rules the day for any pronouncement from authorities ‘doctoring’ the data, and surveillance, even self-imposed, that that ‘doctoring’ is not biased is now a given. Thank you for the documentation of their current consciousness of the review.
==============
I would suggest that .3mm is an interesting number. Over the last couple of years the rate of sea level rise has dropped from 3.4 to 3.1mm/yr. This will put the adjusted rise back to 3.4. Seems more like a propaganda move even if it is justified in some way. Like so many other adjustments that weren’t being made before, they bolster the Goreball Warming Case without being known to the public who only hear the total number quoted and not the history. To do it correctly they would needd to go back and adjust ALL the historic data with this so we have an apples to apples comparison over the full history of the data. If this cannot be done there needs to be two series. A historic one without the adjustment and an adjusted series as far back as a reasonable total can be computed.
Imagine you have a metal bucket almost full of water. And it’s getting warmer. And you want to know when it will overflow, due to thermal expansion of the water, and slight additions due to a dripping tap.
So you do the sums, and determine when it will overflow. But at that time, you find it hasn’t overflowed. You measure the water level, and find it has not risen as expected. So then you realize you didn’t allow for the bucket expanding with temperature as well. So you add an adjustment to the level, and discover that it really DID overflow exactly when expected.
Meanwhile, the floor under the bucket remains dry, but never mind, the MODEL shows that now it’s wet!
You couldn’t make it up!
Oh yes, you can. University of Colorado’s just done so.
And surprise, surprise, we have Nick Stokes turning syntactal somersaults trying to justify another
AGW fiddle.
OK, does anyone who is so sure CU is getting it wrong want to answer the question I asked Jeff? Precisely, measureably, what do you think the GMSL datum should be?
Nick,
It seems that at least some of the sources that CU points to don’t use the modeled adjustment.
http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/LSA_SLR_timeseries_global.php
I Googled “Nick Stokes”
Turns out he’s a fictional character
http://www.crimelab.nl/characters.php?lname=Stokes&fname=Nick
The irony, a fictional man, championing a fictional cause.
17 Kim: I DO remember that movie.Wasn’t someone overpowered and, um, “interfered with”?
Nick does what he always does, deny the obvious and ask an irrelevant question, then repeat that question again and again until he can say people will not answer him.
Pathetic really.
Andy #28,
I think it’s the lack of interest in fact that is pathetic. The complaint is that CU is making an adjustment which has the effect of shifting the datum, or reference level. That is supposed to be terrible.
Well, the relevant questions are:
1. What was the datum before?
2. What is it now?
3. Why is the old datum right and the new one wrong?
Nick-“I think most people realise that (currently small) GMSL rise doesn’t translate well to your local beach, because local land ups and downs are often faster.”
I would wager that for the definition of “most people” that matters-that is, most of all people-your statement is quite wrong. The precise problem with what they are doing is that people will think that GMSL does translate to their local sea level. Don’t get me wrong, I would love it if people were aware of the real cause of major changes in sea levels at most locations, but they don’t know. And just as subsidence will be conflated by knowledgeable people with AGW (and uplift ignored) you can be sure that people will confuse a “proxy for water volume” with trends that actually have impacts. Can’t you see how dangerously misleading this is to the public and policy makers?
The key point to remember is that Tide Gauges show no rise in sea level.
It is entirely possible the whole satellite sea level rise is just another hockey stick con job.
http://climatesanity.wordpress.com/2011/06/06/deception-from-nasa-satellites-are-true-cause-of-sea-level-rise/
Nick,
I’m not sure you are following what they did. The reference level ‘shift’ isn’t the issue, the annual trend in reference level is. A simple shift would be nothing. They are shifting it by 0.3mm/year every single year and adding that trend to the data.
OT. Chris Brown comments at Tamino’s about a new reconstruction and paper in the JoC by Christiansen and Ljungqvist. Jeff, would you consider a post or an invitation to the authors to post at tAV?
Sorry, I buggered up my link to Brown’s comment at Tamino’s: http://tamino.wordpress.com/2011/06/16/open-thread-4/#comment-51593
I thought the only important reference point was the West Side Highway in Manhatten.
Lurker,
I would like to check it out more but will be out of contact this weekend.
If someone can get it in the meantime, I would appreciate a copy by email. Otherwise, I’ll ask the authors when I get back.
Interesting, lurker. The hill ahead just looks steeper, now. Can we get the wax off the runners?
===============
Nick does what he always does,……..repeat until bored.
Here’s a blink comparator of the change:
Jeff #32,
I understand that. But when you are looking for sub-mm/yr accuracy, things that you thought were stationary, aren’t. Land has vertical velocity; seabeds move. There’s more to take into account.
Nick:
Unfortunately their explanation makes no sense…at least if what you are trying to do is produce a useful metric that reflects the encroachment of oceans on human habitat (which AFAIK is one of the main purposes. of discussing “mean ocean height”). Nor is it useful in comparing against measurements of ocean level against satellite measurement.
This “correction” is totally pointless and serves no function that couldn’t be more properly accounted for by estimating the change in the volume of the ocean in the total hydrological cycle.
Nick : “I understand that. But when you are looking for sub-mm/yr accuracy, things that you thought were stationary, aren’t. Land has vertical velocity; seabeds move. There’s more to take into account.”
If scientists want to add a correction for added ocean volume when it comes time to do energy budgets then fine. Just dont add them into a sea level “measurement”.
And to answer your earlier question, the GMSL, just like the global mean suface temperature, is a figure that indicates rate and not much else that is practical to the man on the street. The larger the figure, the larger the alarm.
Just to add some sanity to the discussion in the form of actual data, here’s NOAA’s measurement of MSL trends in feet/century for US harbors. http://tidesandcurrents.noaa.gov/sltrends/msltrendstablefc.htm. They’re all over the map, as high as 3 ft/century to a few that are even negative. It seems to me, that local MSL is all that matters. GMSL, just like global average temperature is a meaningless statistic.
Nick Stokes: “There’s more to take into account.”
Agreed. Like also a lack of monitonicity (is that a word?) – perhaps even on centennial timescales….
Once again ‘(back home’ for both of us):
http://eprints.jcu.edu.au/1855/
NB: The Holocene is littered with such stuff (thank goodness for coral and mollusc U/Th and 14C dates). Just talk to amateur and professional scuba divers about bommie stacking.
Where then the smoothly incrementing ‘datum’?
44-“It seems to me, that local MSL is all that matters”
Indeed! This is even more true of sea level than the temperature business. In case you were wondering the negative trends, mostly in fairly high latitude locations, are caused by the continuous adjustment of the land from no longer having massive glaciers covering it as in the last glaciation. Many of the larger positive trends are also consequences of local geology and have nothing whatsoever to do with global warming. These phenomena are called “uplift” and “subsidence”.
The French (Cazenave & Ablain) wrote to me that the cente of the earth was not the datum. After much discussion, one of them emailed me that the datum was a meshwork of satellites positioned relative to each other. The position of centre of the earth changes by an estimated several mm per year because the earth is a rotating plastic oblate spheriod (to a rough approximation) that develops bulges and deforms as tides slosh around. There seems to be an equatorial bulge happening at present.
An interesting question is, is the volume of free water on the earth constant? Probably not. Even leaving out melting ice, we can surmise. Free water can be released in rock metamorphism by shedding water of crystallisation. Also, there are processes like rheopexy. Does any evaporated water escape gravitational pull? Does water from undersea vents add significant amounts? Does ingestion of watery comet fragments add water? What is the relative effect of fixing water into man-made solid concrete – is it significant? What would be the sea level change from water tied up in a hypothetical doubled timber biomass?
The biggest howler asserts that rising land masses, from isostatic rebound, create larger basins. They do not. Land masses have sloping edges, so that as they rise, they encroach upon sea area and make ocean basin areas smaller, especially of the ocean bottoms move closer to eath centre from reduction in underlying magma.
Nick Stokes at 1, do you believe everything in the FAQs you were quick to note? From the FAQ, “The correction for glacial isostatic adjustment (GIA) accounts for the fact that the ocean basins are getting slightly larger since the end of the last glacial cycle.” Go on, justify it.
“Nick Stokes at 1, do you believe everything in the FAQs you were quick to note? … Go on, justify it.”
Q1, not necessarily – I just think that people looking at a “tweak in the numbers which requires a head scratching” should, while scratching, look at the reasoning behind it.
But yes, this one’s easy to justify. Isostatic rebound – continents rising, magma rising underneath. Fixed amount of magma, so some has to go down. That’s mostly under the sea. Ocean basins larger by volume, not area.
48 Nick Stokes
So you are essentially saying that the volume of water in basins stays constant in the shortish term. I’d agree with that. But, if the ocean bottoms are getting deeper, the tops must be showing more land, hence the appearance of ocean levels falling when referenced to tide marks. You can’t have it both ways.
Nick continues to refuse to address the issue of how misleading this approach of measuring water volume by proxy is to those under the impression that they are being given sea level, not “proxy for water volume”.
Pau; “GMSL, just like global average temperature is a meaningless statistic.”
Nope. GMSL is now a metaphor for the dishonesty of climate scientists.
Mt: “Here’s a blink comparator of the change”
Did they really add the -40 part of the graph to make the data look higher. And they bumped up the rate too. WOW.
What happened to the correction of the mid Atlantic ridge, and other ridges, the increase in volcanoes by a factor of 10 from previous estimates, accelleration or de-accelleration of subduction? Fixed amount of magma?!? In what sense, a scalar? How was it measured? This ignores how magma transforms without the heat and pressure of the environment it came from, to the rock, in a totally different environment, it became. How about the increase in earth’s volume from atmospheric loss, versus decrease from heat loss over the geologic periods? Has it stopped, how large is it, is it constant?
No Nick, the complaints appear valid. There are so many possible corrections that are not known since they are not measured, that the adjustment reflects the assumptions and therefore the potential bias of the authors.
Question: how much volume of water does the 0.3mm add to the ocean compared to the water lost from the ocean due to Trenberth’s 4% increase in atmospheric water vapor?
WUWT had a post on this subject May 5th with numerous comments dissecting the adjustment. I doubt Heartland should be the one credited with the discovery.
http://wattsupwiththat.com/2011/05/05/new-sea-level-page-from-university-of-colorado-now-up/
Nick Stokes:
It’s easy to justify including an adjustment for the change in basin volume of the hydrological balance equation for this, I’m not sure why you’d add it to what should be a measurable.. sea level height.
Sea level height (the real one not the made up version used here) impacts on ocean encroachment on human settlement.
This “adjusted sea level height” is a nothing, it is a totally meaningless metric. I suspect it won’t catch on, because it’s just a stupid way to make the adjustment.
Maybe in climate science circles sea level rise is mainly used as a proxy for increase in ocean volume. Not sure why that would be necessary, if you want to talk about volume, than use units of volume, but OK… whatever.
However, in the popular media, we all know that sea level rise is mainly used to scare people about inundation from global warming. And we also know that every single time the data, whatever it is (sea level, temperature, whatever) gets adjusted, it always is adjusted to look worse than it otherwise would. Every. Single. Time. One can’t help but be cynical in a case like this, even if the explanation isn’t completely unreasonable.
The bottom line is “Lets move the Goal Posts”
Nick Stokes said
June 18, 2011 at 8:05 am
OK, does anyone who is so sure CU is getting it wrong want to answer the question I asked Jeff? Precisely, measureably, what do you think the GMSL datum should be?
Nick,
Roughly speaking, sea level is measured relative to a datum plane or more properly a geoid which represents a gravitational equipotential surface for the planet. As commonly applied, the geoid follows the zero-mm/m/ft/ AMSL or what have you elevation. The common geoid presently in use is defined in the GRS80 standards. Sea level change may be driven by increased volumes of water in the oceans, but it is expressed in linear units (linear as opposed to cubic) relative to the geoid. Isostatic rebound should have little effect on the volume of the ocean basins and certainly isn’t something that it would make sense to “correct” for – not at least by adding a constant. Loading from Pleistocene ice sheets depressed the land under them, and it elevated neighboring regions – rather like pressing your thumb into clay. With the melting of these ice sheets to processes ensued. Isostatic rebound resulted in depressed areas very gradually (rock is pretty viscous) elevating after the load was removed. At the same time surrounding areas sank back toward pre-glacial rest positions. No actual change in the volume of land above sea level ensues from isostatic changes – ‘t’s why its isostatic change. This resulted historically in areas around the borders of the great ice fields that bordered the oceans sinking relative to sea level. The northern shores of the Black Sea, portions of the British Isles and norther Europe that were not under ice sank isostatically as land nearby rebounded. There are Roman-era fields and vineyards that can be observed under water along the western shores of the Crimean peninsula that are under water due to isostatic shifts – local change sin relative sea level due earth movements rather than hydrographic changes. At the same time melting ice fields also caused absolute – eustatic – changes in sea level. Large tracts of land in southeast Asia, Indonesia, and off the eastern coast of Norther America are underwater because of the effects of eustatic change in sea level, as is a significant chunk of land around the Black Sea which was inundated during the Neolithic when eustatic sea level changes elevated the Mediterranean to where it could spill through Bosporus into the Black Sea basin.
Referring back to how sea level is measured, adding a constant to sea-level measurements means that each year UC is arbitrarily redefining the elevation of the geoid they use. The words “sea level change” imply absolute – eustatic – change in sea level relative to the geoid (see any handy discussion of WGS84 and GRS80). When there is talk that low lying islands are going to be inundated due to sea level changes, the inundation will be due to a linear rise of the sea relative to the geoid. The simple point is that sea level is expressed in linear units relative to the datum geoid and volume is measured in cubic units and isn’t relative to anything. UC would seem to have a very difficult time reconciling this.
Thank you Duster!
iso– yeehah!!
Nick have you a coherent, and as well reasoned response response?? After all, you were the one who posited the fixed amount of magma that would be inherrent to the iso conditions. As in, what other iso assumptions are in lay besides magma? As several have alluded to.
Duster,
That is indeed admirably detailed. But note – an equipotential of the gravitational field – with isostatic rebound, that field changes too.
But “Referring back to how sea level is measured, adding a constant to sea-level measurements means that each year UC is arbitrarily redefining the elevation of the geoid they use.”
is quite wrong. They don’t just add a constant – that’s the sort of thing that gets garbled in blogs and Fox News. What they said in the FAQ was:
“Including the GIA correction has the effect of increasing previous estimates of the global mean sea level rate by 0.3 mm/yr.”
What they do, if they implement the Peltier theory they cite, is to compute a spatially varying correction field. They would use something equivalent to Eq (1) in this Chapter of Peltier. It makes use of glaciation history, viscoelastic mantle properties etc. Nothing like just “adding a constant”.
See all this stuff is silliness. Sea level, is sea level relative to land. Duster has provided the definition, and I have to note that CU would not be able to make an adjustment to sea level unless they had a datum already established. The datum is not the issue, the issue is whether it is rational to adjust ‘sea level’ for tectonic plate rebound which decreases actual measured ‘sea level’..
The last sentence answers itself.
If they want to use sea level as a proxy for ocean volume, then the series shouldn’t be titled ‘sea level’, it should be called ‘ocean volume anomaly’ measured in inches/mm. See how simple it is.
If you are a scientist looking to use data, then you don’t want this noise added in. You want the data and you can add your own stupid ‘volume correction’. If you are a politician with a certain political goal, this is 20 percent better than the old weak kneed sea level plot.
Call it what it is, and I have no issues with it.
It is also completely silly just on the phenomenological evidence alone!
Starting with the classical studies in the Bahamas and on the Huon Peninsula, Papua New Guinea by Chappell et al., we now have a wealth of high resolution U/Th and corrected C14 dates on un-reworked corals in unambiguous growth position from all over the world for the last <10,000 years.
The temporal resolution of that database, especially since the development of accelerator and laser ablation high res. mass spec. techniques is now <<100 years. That data base shows that frequent oscillations in global sea level for a host of possible causes are ubiquitous – even in just the last 3000 years.
So why are we now indulging the AGW crowd and especially their somewhat more academic/pedantic apologists in hair-splitting, esoteric discussions of how many archangels can balance on the head of a pin???
Jeff,
“See all this stuff is silliness. Sea level, is sea level relative to land. Duster has provided the definition,”
But that’s not what he said. He said, correctly,
“sea level is measured relative to a datum plane or more properly a geoid which represents a gravitational equipotential surface for the planet.”
That surface is determined by the distribution of mass – continents, sea, mantle, everything. And it moves.
And Steve
“So why are we now indulging the AGW crowd and especially their somewhat more academic/pedantic apologists in hair-splitting,”
It wasn’t I who put up a post about a 0.3 mm/yr adjustment.
Duster wrote – “No actual change in the volume of land above sea level ensues from isostatic changes – ‘t’s why its isostatic change.”
Are you sure that you don’t mean weight rather than volume? It’s a gravitational effect, Mn/d^2 thingo. Not all rocks have the same density. Of course, if you do mean weight, then the calculations of ocean water volume change become nigh impossible from first principles, because too little is known of the distribution and movent of rocks of specified density. Especially, Nick, rocks at spreading centres and “maga movement”. Rock movements are not everywhere at equilibrium now, probably never will be.
Indeed, sea level changes are nigh on impossible to express to the extent quoted, because it’s a tiny change rattling around inside a huge error envelope.
I’d also question whether the geoid is used as a primary reference. I think the satellite framework, related to star positions, is primary; then this is related to the geoid, which is ever-changing, but for practical convenience is often expressed by a model like GRS80.
With this little essay, I’m giving up dancing on pins on this topic. In a perfect world, there would be a credible, agreed figure for ocean level change – if any exists – measured against an agreed datum that matters. No more confusion is needed.
Maybe I can help Nick understand what is wrong with this “adjustment”-this is an unmeasured physical process involve in theoretical explanation of the the measured change. By adding this effect to the data, rather than including it into explanatory models, you corrupt the observations with 1) uncertainty and 2) what the actual measure, in this case, they become a “proxy for ocean volume” rather than an actual measure of actual sea level. To put this in terms that Nick can understand, suppose people were taking the cooling effect of anthropogenic aerosols and “adding” it as a warming back into the observed temperatures. That would be quite wrong and I suspect that even Nick can see why that would be wrong. Beyond that, it’s highly misleading to the public, who think they are getting one measure but in reality are getting something else.
TTCA #66,
No, the adjustment doesn’t introduce uncertainty, you had that already. People say that the GIA is at odds with the common understanding of sea level. What I’ve tried to bring out with this question is that, on the mm level, you don’t have such an understanding that can be expressed consistently. Jeff said it’s measured relative to land, but that’s not how we think of it – we think of land altitude relative to the sea.
I’m glad Duster came up with the proper concept – relative to a geoid, or gravity equipotential – because you probably wouldn’t have believed me. It corresponds to the common expectation that if you stay ar sea level, you won’t have to go uphill. In that context, the GIA is exactly right. If the land rises and the sea-bed falls, the grav equipot follows that motion. If the sea surface does not follow it, then it is indeed rising relative to the datum.
What the GIA provides is an estimate of the rate of movement of that datum. If you don’t have it, and stick to the GRS80 (say) without adjustment, then in due course the GRS80 will have to change (because it is no longer an equipotential) and GMSL will suddenly make a jump. I’m sure you’d love that.
Nick Stokes:
Duster doesn’t agree with your conclusions, and neither do I:
The proposed correction to sea level is entirely dumb and makes no sense regardless of the angle one looks at it.
I’ve noticed they are backing off and are now planing on providing a non-GIA product in addition to the (entirely useless) one with GIA included.
As I said above, the proper place to include isostatic rebound is in a volumetric correction to the hydrological balance. A linear correction is in the wrong units,.
You apparently though it important enough, that you came riding in on your white horse to protect the honoe of these besmirched researchers.
As an aside, the variation in sea level is around 3 mm/year for the last century. This represents a 10% correction to that. Large enough to matter.
Carrick,
the papers I have seen had the sea level rising at about 1.2-1.7mm/yr up till after the beginning of the satellite era with few or no rises near 3mm. Do you have a link handy on the 3mm for the last cent? It would be interesting to compare the papers methodology and sources. Maybe I got the denier stuff again! 8>)
Oh come on Nick. You know you have no quantitative evidence for your assertion “If the land rises and the sea-bed falls”. If you do, produce it or butt out.
Geoff #71,
It goes back to Archimedes. If you get into the bath, the water level rises. Get out, and it drops.
But OK, from the CU FAQ:
“GIA is not caused by current glacier melt, but by the rebound of the Earth from the several kilometer thick ice sheets that covered much of North America and Europe around 20,000 years ago. Mantle material is still moving from under the oceans into previously glaciated regions on land. The effect is that currently some land surfaces are rising and some ocean bottoms are falling relative to the center of the Earth (the center of the reference frame of the satellite altimeter).”
Carrick #68
“The proposed correction to sea level is entirely dumb and makes no sense regardless of the angle one looks at it.
I’ve noticed they are backing off and are now planing on providing a non-GIA product in addition to the (entirely useless) one with GIA included.”
Of course, you can give a measure relative to a defined “geoid” like GRS80. But if things move, that can’t stay fixed forever. When GRS20 or whatever comes along, the accumulated adjustment will come all at once.
Duster #59, Carrick #68
“The simple point is that sea level is expressed in linear units relative to the datum geoid and volume is measured in cubic units and isn’t relative to anything. UC would seem to have a very difficult time reconciling this.”
This isn’t true. Peltier, in this review article, shows how it is done. Eq (1), the unperturbed equation for the geoid evolution, is in length units. And so is the GIA correction, Eq 5.
Nick Stokes
Adjustments to the “geoid” related to isostatic changes that result from the redistribution of ice and water masses are not fast and do not occur all at once. These changes require 10’s of thousands of years to get anywhere near completion. As you are aware that is largely why UC felt they needed to put in a fudge factor. i.e. to cover this long ongoing process.
The isostatic movements are accommodated by gradual lateral ductile deformation in the earths mantle. Thats why the changes take so long.
Note that both the continental land area and the position of the coastline are not fixed. There are a number of shallow “continental seas” like Hudson Bay and the Baltic sea that are gradually emptying as the sea-bed rises. This water has to go somewhere, a redistribution issue. Much of it is accommodated by slow sinking in the major ocean basins. If the process goes to completion some of these shallow sea areas will eventually be above sea level. The coast will migrate landward and/or seaward elsewhere as well depending on how the water is redistributed and on other isostatic and tectonic processes.
My opinion is that the modeled adjustment UC have used can only be provisional with the current state of knowledge. However, I am in agreement with others here who see the new UC practice as adding confusion. What I want to know is whether land will be engulfed by rising sealevel, for instance low-lying coral atolls. So the question everyone most wants to know is “will the sea rise next to my place?” This is a local question. To answer the question I would begin by asking- what is happening to sea level relative to a fixed geoid (as fixed as it can be)? Then I would want to know how any additional water volume is going to be redistributed on this spinning planet and what that might do to my local sea level. These questions should be answered by careful analysis of measurements from satellites and tide gauges. These measurements can accommodate isostatic and tectonic movements, water addition/subtraction and thermal expansion/contraction. Do we really need more than that?
Rob R
“Adjustments to the “geoid” related to isostatic changes that result from the redistribution of ice and water masses are not fast and do not occur all at once. These changes require 10’s of thousands of years to get anywhere near completion.”
Yes. All that’s saying is that in the current time frame the land masses (and other parts of the surface) have a velocity, small, but substantial on a scale of mm/year. And fairly uniform, because the momentum is huge.
“My opinion is that the modeled adjustment UC have used can only be provisional with the current state of knowledge.”
Yes, so is everything in science. But it’s reached the stage where the GIA adjustment is more realistic than zero adjustment.
“So the question everyone most wants to know is “will the sea rise next to my place?” This is a local question. To answer the question I would begin by asking- what is happening to sea level relative to a fixed geoid (as fixed as it can be)? Then I would want to know how any additional water volume is going to be redistributed on this spinning planet and what that might do to my local sea level.”
The biggest question there is, what is happening to my place (land) relative to the geoid (fixed or not)? Then what is happening to the water, globally? Then, maybe, what might cause the water to pile up unevenly?
The GIA closes the water system – the second question works better. The price is taking account of a moving geoid. That isn’t the hard part of working out what is happening to your land.
Datum geoids, my ass!
Nick, this is getting hilarious. If what you claim is true, that the proper way to measure “sea level change” is to calculate the supposed volume of water and then represent it as virtual sea level in a hypothetical bowl with a fixed surface area, then the natural conclusion must be that the methodology used until now must be utterly wrong. Strange that you did not seem to notice this egregious error and attempt to correct it. 😉
Actually what they have done is to move the pea under a different shell by changing the focus of their research [bold mine]:
But that is OK because there are others who are interested in the actual sea level change:
So you see, this is all a result of a sudden realization of where their true research interests lie.
However, it occurs to me that the new methodology also has Climate Science applications in estimating “true” mean global temperatures. I can just see GISS and CRU implementing it now:
When carrying out research on global warming, the real ‘focus’ is the amount of heat energy in the system and not the actual local temperatures themselves. However, the ocean seems to absorb some of that heat energy well below the surface so that this ‘mitigates’ the apparent change in surface temperatures. The TMH (Trenberth Missing Heat) adjustment is guesstimated at .03 degrees per year so that this amount is added on to the change in the measured temperatures annually to correct for what the level of global temperatures should be as definitively shown by climate models.
Roman,
You seem to find a lot of regular science hilarious now. You could try reading some of Peltier’s papers. CU is simply implementing standard theory.
Or if you’re so scornful of geoids, perhaps you could tell us how you would define the sea level datum?
Sea level is the level of the sea relative to land. Think of it as a proxy for shoe wetness. Whichever reference datum is used for satellites, they have it nailed down fairly well when they add 0.3mm/yr as a correction for ‘land movement’.
The correction is just gaming a number which every layperson understands “sea level” and increases the scariness by 20%. Any of the climate scientists can simply report the trend in sea level rise and make the claim that you should simply have read the paper. It sounds all too familiar.
A number which means just what they say that it means.
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Nick, I have little tolerance for scientists who are more interested in propaganda than science.
There is nothing wrong with doing research on how the earth may be changing nor in CU wishing to study the volume of the water in the ocean to determine the factors that influence the amount of that volume. But as they state themselves, “There are other science questions that researchers are investigating, such as the effect of ocean volume change on local sea level rates,…”. The “local sea rates” give information on how the surface level of the ocean is changing relative to the boundary of the land area on which we live, information that is considerably more relevant to all of us who live on that land. This is simply NOT the same information as that contained in the volume change data.
Until now, the CU site had posted data on the local sea levels along with graphs depicting that data. In particular, those graphs seemed to indicate a recent slowing in the rise of that sea level. However, in the reorganization of their web site, they have decided to change the type of information they will be displaying to reflect the “focus” of their research (a focus which I do not believe has also simultaneously changed at this point in time) . The sudden decision to “implement standard theory” when that theory has been around for a long time seems like a lame excuse given that the result will guarantee rates of increase higher than those in the data which we have been viewing there in the past. You can also be sure that those higher rates will be incorrectly used by others in predictions of how much the surface level may rise in the future.
I am not scornful of geoids per se. They may be a useful approach for defining an absolute global mean sea level (as would be required for defining altitude on land or the depth of the ocean floor), but I don’t see that as necessary for measuring change in the current level of the water’s surface relative to the land boundary. Simple subtraction of consecutive relative measurements at a given point tell you the change at that point and suitably done averaging of those individual changes gives a global value. This should apply to satellite measurements as well as tide gauges. One would assume that this is the way it would work before the GIA adjustments are applied anyway.
They wish to show the adjusted data – fine, however, let’s also see the unadjusted data as well. It’s not that difficult.
Nick, I am sceptical that you would have have made such a spirited defence of University of Colorado’s new sea-level change metric had it subtracted 0.3mm/year.
In fact I believe that you would be attacking UC for confusing the Public with a metric that doesn’t relate to eustatic changes.
But that is par for the course for AGW defenders. You want to argue from whatever side is advantageous politically and science comes a poor second.
Why is Aviso sea level so different from CU?
Nick:
These are fields not scalars.
Don:
I have no idea why Nick thinks it’s such a great idea, why he feels so much energy over this nor why UC did so. NIck’s reference just makes it how clear the whole correction is to modeling assumptions. UC’s decision to keep the non-GIA corrected “true sea level anomaly” height is a good compromise.
I doubt anybody serious about the hydrological balance is going to use the GIA corrected version of sea-level height and anybody trying to make a correspondence to instrumentation is going to want the non-GIA corrected version. That’s whats so weird about this.
Nick, I think I am with you on this, as CU have come up with a new novel way to measure height. The actual height doesn’t change, but we make an arbitrary addition on top due to supposed changes. The value in doing measurements this way is we could then do the same thing for individual’s height. We could let people add to their height by losing weight, lose 20 lbs and add an inch to your height. It would help reduce obesity, law enforcement could have more fun in trying to identify if it is really the person in the passport or DL – it says he is 5’11” but he only looks like 5’8″. We can take off height if people gain weight thereby lowering their self esteem even further, what fun.
Yup I gotta hand it to those guys at CU, they deserve additional funding for measurement research. Einstein had nothing on them he just allowed the ruler to get shorter, these guys can pull a number out of their butts.
I spit, too. At the Shoreline. But not into the wind, into the ocean.
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It isn’t a question of ‘datum’, it is a question of whether an annual sea volume addition makes sense to include in a sea level plot.
And the answer is an obvious no.
67-“No, the adjustment doesn’t introduce uncertainty, you had that already.”
I meant additional uncertainty, I thought that was obvious but evidently not.
And you are still failing to grasp the point. Would you or would you not acknowledge that it would be inappropriate to call something the measured global mean surface temperature, if modeled aerosol cooling effects were added back in as warming to get a “proxy for greenhouse warming” while still dishonestly calling it “measured global mean surface temperature”? Because that would be the same damn thing.
You measure something to a fixed reference. You are saying that if the reference original chosen changes, then the measurement must be changed. This would be like saying “The Grand Kilo has lost mass, so the actual value of the kilogram must be arbitrarily changed to match!” No no no! A fixed geoid once chosen as a reference point is not to be “accounted for” changing in the actual measurement. You cease then to measure from a fixed reference point…which means you have ceased to do any measuring at all, what you are then doing is, well, I don’t know but it isn’t measurement.
This is the type of “science” I hate. If they really want to adjust for the land rising, they should be using real data instead of just linearly padding the numbers. The more meaningful way to measure that would be to measure the total volume of water in the ocean, but we obviously don’t have near enough real data to do that. For an analysis of the impacts of climate change, what really matters is the sea level rise compared to the land we all live on. I could care less about some fantasy Gaia untouched by man. I want to know the impacts of climate change on man compared to the impacts of various solutions to climate change on man. In this case, it’s pretty clear that sea level rise, which has been one of the alarmists’ biggest scare tactics with maps showing wide swaths of land taken over, has not hurt man over the last century which casts future catastrophic predictions in doubt.
There’s a new entry on the CU Blog, “GIA FAQ Updated with Peltier Reference“.
Peltier gives refs to his papers on the GIA adjustment.
He continues to miss the point that has been made so clearly by everyone here (except Nick) and says that
“There should be nothing controversial about the necessity of making this correction. Since the need of it was established 10 years ago I’m surprised that it should be attracting attention!”
If it really was shown to be necessary 10 years ago, one wonders why CU have only just this May decided to include it!
Nick: “Andy #28,
I think it’s the lack of interest in fact that is pathetic. The complaint is that CU is making an adjustment which has the effect of shifting the datum, or reference level. That is supposed to be terrible.
Well, the relevant questions are:
1. What was the datum before?
2. What is it now?
3. Why is the old datum right and the new one wrong?”
This would seem to be pretty simple Nick. The datum that was measured before was level. It should still be level, but it is not. If they want to have a new datum for volume, then have a new one. But let’s not call it “Sea Level” when that is not what it is. You know perfectly well that when the rate of sea level rise is used as a part of the global alarm system that they are not going to remove that 0.3 mm per year first. Instead they are going to use it along with pictures of Manhattan under water.
Well here is the answer to why they made the change now: A new sea level paper with a well known shape.
Click to access pnas_kemp-etal_2011_sea_level_rise.pdf
Don Keiller #82,
“Nick, I am sceptical that you would have have made such a spirited defence of University of Colorado’s new sea-level change metric had it subtracted 0.3mm/year.”
I can’t imagine that there would have been an attack to be defended. But I’m always in favor of finding out the facts.
The coefficient of expansion of sea water change quite dramatically between the temperature of the very deep ocean (say ~0 to 4C), and warm surface water (say ~20-25C). The difference is a factor of more than threefold. So it strikes me that while there is nothing inherently wrong about applying a correction for glacial rebound if you claim to be trying to better quantify the ‘real’ rate of ocean volume growth, it does seem a bit of a stretch to say that this really addresses the overall uncertainty very much. The really big uncertainties (thermal expansion vs net water volume addition and historic tide gauge variability) are not much impacted by the glacial rebound adjustment. If anything, I think adding a constant 0.3 mm per year just means the difference between 100 years ago and now (in terms of total rate of ocean volume growth)is smaller…. less relative impact from net warming.
But they still should not call the adjusted value “sea level rise”; better would be “estimated adjusted volume increase” or something, NOT “sea level” . To call the results “sea level” is willfully misleading tot he public….. they should go back to the real seal level rise. Glacial rebound is not going to change significantly over the next 1000 years or so; to add that effect and call it “sea level rise” is politically motivated rubbish of the worst kind.
Nick Stokes,
I am shocked that one as bright as you can’t see this rebound adjusted value of “sea level” for what it is: a misleading presentation that appears designed to ‘enhance’ the influence of global warming on sea level as presented to the public. This episode is exactly the kind of thing that sets off lots of people (me included!), who clearly do understand the technical issues, and it is indeed that understanding that sets them off. Climate scientists, and those who profess to support the findings of those climate scientists (including Nick Stokes) would do well to use this case as an example of exactly how NOT to present the results of climate science to the public. If climate scientists want credibility with the public, then a good place to start is not misleading people. People generally understand what the words “rising sea level” mean; using that description for something else is just deceptive.
PaulM #92,
“If it really was shown to be necessary 10 years ago, one wonders why CU have only just this May decided to include it!”
It really was. I cited Peltier’s papers earlier. Here is one from 1996 where he is grappling with one of the key issues – viscous properties of the mantle. Knowledge of this is needed, and was much improved when results from the GRACE satellite came through.
And again, it is just 0.3 mm/yr.
And again, no, SteveF #96, Scott B #91 they are not just “adding a constant 0.3 mm per year”. That isn’t how it is done. Read Peltier.
Nick Stokes # 99,
““adding a constant 0.3 mm per year”. That isn’t how it is done. Read Peltier.”
Of course that is not how it is done! Glacial rebound is a long studied effect that is reasonably well defined. This far away from the end of the last ice age the rebound rate is pretty close to constant on multi-century time scales… so the constant 0.3 mm per year is probably not far from correct. But the details of how it is done are completely irrelevant.
The issue here is how the adjustment due to rebound is “added” to the MEASURED average sea level rise and then reported as if that were the “sea level rise”, as normal people understand the words “sea level rise”. The implication being that the MEASURED sea level is rising significantly faster that we thought is was. That is simply not the case, and you known that as well as I do. The ~ -0.3 mm per year rebound contribution is NOT going to change much in the next few hundred years. Sure, it makes sense to try to better understand all the contributors to sea level rise. But just as surely it makes no sense to confuse people about the actual sea level rise. The issue (which you seem to not want to address) is why calling that rebound adjusted value the real “sea level rise” is a very bad (and IMO deceptive) way to present the data to the public.
I can see the headlines now in The Economist: “Scientists discover flaw in calculation of sea level….. it is even worse than we thought. The UN has decided to hear new complaints from South Pacific Islanders.” It is just politics Nick, not science. Please don’t be obtuse about something so simple as this… this a perfect example of an own-goal.
But Steve, the headlines weren’t in the Economist. They were on Fox News – “Research Center Under Fire for ‘Adjusted’ Sea-Level Data”
with the fair and balanced lead-in:
“Is climate change raising sea levels, as Al Gore has argued — or are climate scientists doctoring the data?
The University of Colorado’s Sea Level Research Group decided in May to add 0.3 millimeters — or about the thickness of a fingernail — every year to its actual measurements of sea levels, sparking criticism from experts who called it an attempt to exaggerate the effects of global warming.”
And the “expert” turns out to be a lawyer from the Heartland Institute. And it misleads about the adjustment. And they aren’t climate scientists anyway, they are oceanographers in the Colorado Center for Astrodynamics Research at CU.
NIck Stokes #101,
OK I get it, you simply will not engage the real issue (to wit, what they did exaggerated the measured rise in sea level by ~10%), and you prefer to carry on about Fox News. Too bad. Well, even if you will not discuss the real issue, I hope you at least understand how dumb an idea it was to substitute that new graph for the one they had been using for years, while continuing to call it the same thing.
By the way, I do not doubt that the rather extreme right wing journalists at Fox News (they don’t reach Joe Romm’s level of extreme, but they are competitive), did not do a “fair and balanced” job of covering the issue.
But they should have had nothing about sea level to comment on; that is the point.
Boballab,
I thought Mann’s new paper was part of his special Comedy Climate Series. I understand they are looking forward to when the US is bankrupt and the funds are cut off. 8>)
It’s interesting just how far Nick and his ilk have drifted to the left for Fox News to look ultraconservative. I don’t watch them…for various reasons I prefer CNN & the obviously left-leaning BBC news…but study after study has shown Fo xNews to be either centralist in their news reporting or just a bit right of center. (I think Hannity is a synonym for insanity and Beck really is a crazed circus clown, but truth will out.)
Speak of the devil, there’s a new report coming out, confirms previous studies.
Nick:
Um… since when can’t oceanographers be climate scientists too? (There is no separate profession “climate scientist”, so how did you determine this fact?)
Carrick,
I didn’t say FN was ultraconservative – that was SteveF (kind of). I said they were wrong. And yes, I implied they were not fair and balanced in this report.
Nick,
A little spoon feeding for a busy guy plz. How did the article mislead about the adjustment?
Jon’s ‘Uninformed’ is Newspeak for ‘doesn’t buy the narrative’.
=================
Jeff #106,
They said “decided in May to add 0.3 millimeters…”
which is not what they did at all. They decided to implement Peltier’s GIA. They said in their FAQ:
“Including the GIA correction has the effect of increasing previous estimates of the global mean sea level rate by 0.3 mm/yr.”
They probably should have said “approx 0.3mm/yr” for even greater clarity.
Not to worry, those good ol’ soldiers Rahmstorf and Mann are riding to the rescue:
http://thegwpf.org/science-news/3267-new-sea-level-study-divides-climate-researchers-.html
From the link #109
But other experts doubt exactly this claim. They see a major problem of the new study in the fact that it is ultimately based only on the finding from the coast of North Carolina. That could be too limited for a statement regarding global developments. “This study is therefore not suitable at all to make predictions,” says Jens Schröter from the Alfred Wegener Institute for Polar and Marine Research.
Sounds like a Lindzen-Choi result.
110-There is absolutely no comparison between extrapolating Global results from findings in North Carolina and extrapolating Global results based on the entire tropics. The first is like a tenth of a hundredth of a percent of the world, the second is fully half of the world. Take your snarky, cheap shot nonsense elsewhere.
Nick:
No doubt. Still wondering why you think these guys can’t be called “climatologists”? What makes somebody a climatologist? An IT degree?
Nick, speaking of fair and balanced. You said
Actually there were two “experts”, one was a lawyer, the other John Christy, not a lawyer at all, but an empiricist with a lot more experience than you have in constructive appropriate measures for quantifying data.. Odd how you omitted that.
This isn’t about truth, it never was, or you wouldn’t have omitted part of it.
Carrick,
What the FN report said was
“sparking criticism from experts who called it an attempt to exaggerate the effects of global warming.”
and they quoted Taylor, the Heartland lawyer, saying words to that effect.
They also quoted John Christy. But he (in the quote) didn’t say anything about an attempt to exaggerate. He merely said “To me… sea level rise is what’s measured against the actual coast…”.
When the record’s magnitude has been made larger than actual, it has been exaggerated. When the record’s magnitude has been made smaller than actual, it has been diminished. You are not suggesting, Nick, that John Christy was intimating that the record had been diminished, are you?
=============
Nick #114,
So John Christy said: “To me… sea level rise is what’s measured against the actual coast…”
Jumpin’ Jesus, I wonder how he ever came to that odd conclusion… maybe he just adopts the conventional, widespread understanding of the words “sea level”. What a denier! What a fool! He can’t possibly be a climate scientist!
Steve,
I have no criticism of Christy for expressing that view, I’m merely saying that he cannot be described here as an “expert who called it an attempt to exaggerate the effects of global warming”
And sure, he’s a climate scientist. Whether he’s an oceanographer is another question.
Nick,
This is a perfect example of what is wrong with climate science: well intentioned (but ill considered) efforts to convince a skeptical public to do what you think they need to do. It hasn’t worked so far, and it is not going to . A huge dose of humility, directness, and honesty is what climate science needs,,,, not arm waves about why an obvious distortion is not a distortion (nobody cares about a contorted understanding of the meaning of a commonly understood phrase!).
I have no doubt that the effort to “enhance” the contribution of global warming to sea level increase was well intentioned… I also have no doubt that it was disrespectful of the public and generally stupid. As I said before, it is an absolutely perfect contrary example of what climate scientists need to do to gain credibility with the public. Defending this nonsense does not help your (or their) credibility. When you are deep in a hole, and want a way out, stop digging.
?I think people get Nick wrong. He’s never claimed to believe any of the points he makes in this thread to be superior to others. Again, he is intentionally in a weak position with little to argue from. Sea level means what it says. I think he’s chosen a particularly weak space this time to which he has made little ground but hopefully enjoyed the challenge.
I’ll ask a question of him which may clarify his position, maybe not.
Nick, Do you think that the most accurate description of the modified sea level trend is ‘sea level’?
Swimming soon. Nick’s waist deep in the Big Muddy.
==========
Jeff #119,
I do not believe people get Nick wrong at all, nor do I believe that a defense of idiocy is prudent or wise. It only hurts the objectives of people like Nick to defend clearly indefensible actions. Until Nick (and others like him) object strenuously to this kind of rubbish, climate science will never improve.
Can we talk about Christiansen and Ljungvist? It sends shivers down my spine.
==============
I must confess I’m having great trouble reconciling the overall meaningfulness (to the AGW argument) of this statement by Peltier:
“When the mass-derived contribution is added to the thermosteric contribution it is
furthermore shown that the inference of the net rate of global sea level rise by the altimetric satellites
Topex/Poseidon and Jason 1 is also reconcilable over the GRACE era. It is noted those individual terms in
the budget, especially the contribution from small ice sheets and glaciers, remains insufficiently accurate.
It is demonstrated that the lingering influence of the Late Quaternary ice-age upon sea level is profound
and that closure of the budget requires an accurate model of its impact.”
with this other statement taken almost at random from the voluminous geomorphological literature of the Holocene (noting I can produce mainstream geomorphological literature references to literally dozens of such findings):
“During this ~5000 year period of high sea level, growth hiatuses in oyster beds and tubeworms and lower elevations of coral microatolls are interpreted to represent short-lived oscillations in sea-level of up to 1 m during two intervals, beginning c. 4800 and 3000 cal yr BP. The rates of sea level rise and fall (1–2 mm yr-1) during these centennial-scale oscillations are comparable with current rates of sea-level rise. The origin of the oscillations is enigmatic but most likely the result of oceanographic and climatic changes, including wind strengths, ice ablation, and melt-water contributions of both Greenland and Antarctic ice sheets. ”
So, please help me. How can Peltier say that….it is demonstrated that the lingering influence of the Late Quaternary ice-age upon sea level is PROFOUND
and that closure of the budget requires an accurate model of its impact…. when there is ample evidence of ‘recent’ (i.e. well after the Late Quaternary ice-age) centennial scale oscillations at a rate 5 – 10 times greater than a trend of post-glacial continental rebound?
I am not at all denying (sic) the reality of the effect to which Peltier refers or even questioning his ‘demonstration’. I am just not competent to do that. But I am questioning what its real significance is (i.e. to the AGW argument) in the context of a well known pre-modern era sea level ‘noise’ in even the Late Holocene?
Something doesn’t ‘gel’ here, surely?
Is this just yet another case of ‘climate scientists’ working in incestuously/doggedly ‘splendid isolation’ from other ‘normal’ science disciplines?
One thing I will note is that in the few areas I do know something about I am getting real tired of reading totally outrageous examples of post-modernist AGW group think even in the pages of Nature.
Steve,
I think he enjoys the discussion more than the point. Otherwise his points would be more pointed.
Jeff #119
“Nick, Do you think that the most accurate description of the modified sea level trend is ‘sea level’?”
Jeff, that’s why I turned it around – what do you think “sea level” actually is? Which you never really answered.
But yes, given that ambiguity, another term might be better. eg GMSL 🙂
Actually, I think I’ve been clear to my definition. It is an average measure of ocean water relative to land.
Also, the anonymous comment #79 was me. Sea level is simply a proxy for shoe wetness.
Seriously, rather than the GMSL, is there a real definition for the new series which would more accurately describe the series. IMO, sea volume anomaly would be more accurate per your initial comments.
I don’t usually agree with Nick either, and it can be frustrating – but he doesn’t ever (that I can recall) make his comments or arguments personal. I don’t recall too many discussions where people abandoned their original position (myself included). In spite of the fact that Nick pisses me off sometimes (recall the ethics discussion over “hide the decline”) he gets a pass from me. Let’s face it, the world would be a boring place without arguing over our passions. Some day Nick, we’ll go for a beer (you’re buying 🙂 ).
LL #127
“you’re buying”
Hey, what about all that oil money? When I had a beer with Mosh, as I remember he paid with a $100 bill 🙂
But yes, if you ever make it to Oz, I’d be glad to buy you a beer.