From the British Antarctic Survey
New projections of ‘uneven’ global sea-level rise
Reporting in the journal Geophysical Research Letters researchers have looked ahead to the year 2100 to show how ice loss will continue to add to rising sea levels
Sophisticated computer modelling has shown how sea-level rise over the coming century could affect some regions far more than others. The model shows that parts of the Pacific will see the highest rates of rise while some polar regions will actually experience falls in relative sea levels due to the ways sea, land and ice interact globally.
Reporting in the journal Geophysical Research Letters researchers have looked ahead to the year 2100 to show how ice loss will continue to add to rising sea levels. Scientists have known for some time that sea level rise around the globe will not be uniform, but in this study the team of ice2sea researchers show in great detail the global pattern of sea-level rise that would result from two scenarios of ice-loss from glaciers and ice sheets.
The team, from Italy’s University of Urbino and the UK’s University of Bristol, found that ice melt from glaciers, and the Greenland and Antarctic ice sheets, is likely to be of critical importance to regional sea-level change in the Equatorial Pacific Ocean where the sea level rise would be greater than the average increase across the globe. This will affect in particular, Western Australia, Oceania and the small atolls and islands in this region, including Hawaii.
The study focussed on three effects that lead to global mean sea-level rise being unequally distributed around the world. Firstly, land is subsiding and emerging due to a massive loss of ice at the end of the last ice age 10,000 years ago when billions of tons of ice covering parts of North America and Europe melted. This caused a major redistribution of mass on the Earth, but the crust responds to such changes so slowly that it is still deforming. Secondly, the warming of the oceans leads to a change in the distribution of water across the globe. Thirdly the sheer mass of water held in ice at the frozen continents like Antarctica and Greenland exerts a gravitational pull on the surrounding liquid water, pulling in enormous amounts of water and raising the sea-level close to those continents. As the ice melts its pull decreases and the water previously attracted rushes away to be redistributed around the globe.
Co-author Professor Giorgio Spada says, “In the paper we are successful in defining the patterns, known as sea level fingerprints, which affect sea levels.
“This is paramount for assessing the risk due to inundation in low-lying, densely populated areas. The most vulnerable areas are those where the effects combine to give the sea-level rise that is significantly higher than the global average.”
He added that in Europe the sea level would rise but it would be slightly lower than the global average.
“We believe this is due to the effects of the melting polar ice relatively close to Europe – particularly Greenland’s ice. This will tend to slow sea-level rise in Europe a little, but at the expense of higher sea-level rise elsewhere.”
The team considered two scenarios in its modelling. One was the “most likely” or “mid-range” and the other closer to the upper limit of what could happen.
Professor Spada said, “The total rise in some areas of the equatorial oceans worst affected by the terrestrial ice melting could be 60cm if a mid-range sea-level rise is projected, and the warming of the oceans is also taken into account.” David Vaughan, ice2sea programme coordinator, says, “In the last couple of years programmes like ice2sea have made great strides in predicting global average sea-level rise. The urgent job now is to understand how global the sea-level rise will be shared out around the world’s coastlines. Only by doing this can we really help people understand the risks and prepare for the future.”
Co-author Jonathan Bamber, of Bristol University, says, “This is the first study to examine the regional pattern of sea level changes using sophisticated model predictions of the wastage of glaciers and ice sheets over the next century.”
GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2012GL053000
The gravitationally consistent sealevel fingerprint of future terrestrial ice loss
- Sea-level fingerprints of future terrestrial ice melt are studied
- SLR in Arctic ocean mainly due to ocean response with small ice melt impact
- SLR due to ice melt critical to Equatorial Pacific Ocean and Oceania
Giorgio Spada, Jonathan L. Bamber, Ruud Theodorus Wilhelmus Leonardus Hurkmans
Abstract
We solve the sea-level equation to investigate the pattern of the gravitationally self-consistent sea-level variations (fingerprints) corresponding to modeled scenarios of future terrestrial ice melt. These were obtained from separate ice dynamics and surface mass balance models for the Greenland and Antarctic ice sheets and by a regionalized mass balance model for glaciers and ice caps. For our mid-range scenario, the ice melt component of total sea-level change attains its largest amplitude in the equatorial oceans, where we predict a cumulative sea-level rise of ~25 cm and rates of change close to 3 mm/yr from ice melt alone by 2100. According to our modeling, in low-elevation densely populated coastal zones, the gravitationally consistent sea-level variations due to continental ice loss will range between 50 and 150% of the global mean. This includes the effects of glacial-isostatic adjustment, which mostly contributes across the lateral forebulge regions in North America. While the mid range ocean-averaged elastic-gravitational sea-level variations compare with those associated with thermal expansion and ocean circulation, their combination shows a complex regional pattern, where the former component dominates in the Equatorial Pacific Ocean and the latter in the Arctic Ocean.
The BAS does some good science, especially in geology, but some of their claims are out of the mad box or reported before any real analysis of the data. Another model based claim probably using a model that assumes that glaciers are all melting etc. etc. etc.. Some glaciers melt and shorten but others grow and it is surprising how easy it is to ignore those that grow if you believe in AGW.
Models can be useful but empirical measurement is far better and follows reality.
One might suspect that if you added water to the world’s oceans, it would tend to migrate towards the equator due to the spinning of the Earth, so that amount of local seal level rise would be a function of latitude.
Models confirming models?
“Sophisticated computer modelling”… lost me right there …. how about rigorous
data measurement and collection….
Another piece of J-science. What warming oceans? What melting icecaps? Greenland doesn’t appear to lose anything significant and whatever it loses is more than made up for by the growing East Antarctica ice shield. And a percentage loss on either side would have no perceptable effect on the shapes of the geoid, so that is a complete red herring.
I know this is mostly about ice and uneven sea level rise but seeing as ice, terrestrial rebound and heat induced expansion are debated endlessly, I think it would be as well to remember the contribution of human induced groundwater loss- which ends up in the oceans. I think it gets ignored because its not as epic as continental ice sheets sliding into the sea en masse.
Here’s a recent report from NASA on groundwater loss in the (not so) Fertile Crescent. It comes from data recorded by the two GRACE satellites, which can measure gravitational anomalies at or near the Earth’s surface including water loss. The report sheds light on why sea levels are rising (although NASA doesn’t care to mention the obvious link, preferring to focus on the freshwater resources issue):
http://www.nasa.gov/mission_pages/Grace/news/grace20130212.html
A few sime calcs throw this loss into perspective:
The earth’s oceans cover 335 million square km
The loss quantified in the report is 144 cubic km
This equates to a 0.43mm rise in sea level over 7 years.
That might not seem like much but it is a huge contribution to sea level rise considering 1) The measured rise is between 1.7mm/yr and 3.3mm/yr (the now-disputed satellite data)
2) This is a tiny portion of the worlds land surface and, according to the report, less than India’s loss.
That means that the Fertile Crescent plus India have contributed 1mm or between 1/12th and 1/23rd of the sea level rise in 7 years. If you add in Bangladesh, SW United States (the GRACE satellites had already found California alone had lost 30 cubic km), the vast reserves being depleted in N. Africa and many other areas around the world, groundwater loss is a significant contributer to sea level rise. Yet, it is hardly ever mentioned as a major culprit. I even wonder if some researchers are convieniently forgetting it. after all, shaving off a few tenths of a millimetre due to a non-climate cause of sea level doesn’t serve their case at all.
I’m sure it’s interesting work and fine if people use it as a planning tool but…
Roman London can be between 6 to 8m below the current city street level. A large area of fertile land called Doggerland once existed in what is now the North Sea and we inhabit upland which would have been considered second rate. New York was once a beautiful, mosquito plagued bit of swampy forest.
We created problems for ourselves when we decided that what we have now is how it should always be and that engineering was a bad way of dealing with change. Are we King Canute?
Gosh I really wish I was as bright as some of the other commenters here. Able, without even reading the paper, to dismiss this work as rubbish because of their superior intelligence and knowledge. Able, in a few seconds of thought, to cut through to the heart of the matter, spotting glaring errors that teams of so-called scientists, who have no doubt spent entire careers studying the subject-matter, have stupidly missed.
How such intellects are wasted carping on about AGW! Anthony, you need to organize some sort of program to harness these wonderful minds that you have gathered around you, and set them to work on some of the world’s real problems. We’d have fusion power cracked in a few weeks, I’m sure. Mars terraformed and colonized by 2015.
An interesting article probably, but really, the gravitational pull of the Antarctic ice cap ??? OK, I’ll think about that, but on the surface (sorry about that) it seems kind of unlikely to have a significant or even measurable affect on sea level.
Anyway, I think what we have here is probably an elaborate model based on numerous somewhat iffy assumptions with no empirical verification. I’m not sure that the world needs more of those.
As far as I can tell, the paper itself is paywalled.
Models are always interesting. How well they predict actual events always seem to be a challenge. Virginia Institute of Marine Science (VIMS) says their data show an acceleration of the rate of sea level rise of 0.3 mm/yr but have some qualifiers on statistical significance of data. Their report, at least, had standard deviations for predicted rise between now and 2050. I was beginning to think that climate-related reports couldn’t get published with such things as that. http://www.vims.edu/newsandevents/topstories/boon_slr.php
Asa usual with these type of reports there is one MAJOR problem . There is no significant ice loss anywhere. Even Cryosphere today (a warmist site) is showing global ice right on normal.
The team considered two scenarios in its modelling. One was the “most likely” or “mid-range” and the other closer to the upper limit of what could happen.
And the lower limit wasn’t alarming, so we don’t talk about it, eh?
On the highly dubious assumption that there will be significant warming over the rest of the century, that means the atmosphere should be able to hold more moisture, which in turn means more precipitation over the parts (+99%?) of Greenland and Antarctica that will experience no glacial melting.
It is probably safe to assume this is one of many relevant factors which have been ignored in these models.
Sophisticated computer modelling has shown…
This was the point where I stopped taking their results seriously.
Nigel Harris says:
February 21, 2013 at 4:10 am
Gosh I really wish I was as bright as some of the other commenters here. Able, without even reading the paper, to dismiss this work as rubbish because of their superior intelligence and knowledge. Able, in a few seconds of thought, to cut through to the heart of the matter, spotting glaring errors that teams of so-called scientists, who have no doubt spent entire careers studying the subject-matter, have stupidly missed.
======
Well yes, Nigel, it might help if you were a bit brighter. And perhaps a fraction less abrasive.
BTW, the press release was posted at Science Daily several days ago, so some of us have had an opportunity to look it over and come to some conclusions.
Nigel Harris says: (February 21, 2013 at 4:10 am)
“We’d have fusion power cracked in a few weeks, I’m sure. Mars terraformed and colonized by 2015.”
If all the wasted billions of dollars/euros/whatever currency were put to solving these kind of things instead of to the nonexcisting problem of CO2 induced Global Warming, you would be surprised at what could have accomplished.
And the good people here at WUWT have seen too much modelling to take every new study seriously. The modelling these days is almost everytime contaminated with presumptions that have nothing to do with reality and are not backed by real life measurements.
‘The Cause’ is responsible for a lot of miserable research and ditto science.
Nigel Harris: Just maybe these “persons of superior intelligence” simply noticed something obvious.Just like a child can see that the emperor has no clothes.
We in Finland lived next to the Soviet Union for decades.The AGW-religion has now entered similar phase that they had before the collapse; worn out Breshnevian mantras try to keep the faithful true to the “cause”. Only the brainwashed ones believe.
With Obama, you too can now taste the socialism.The sickening feeling that the leaders are actually against you.
I spotted an uneven bit of sea level off the south coast of the UK today…
Sorry – it was a wave…
Don K February 21 2013 at 4:11 am I have lingering doubts also.
Not that this is my strong point, but it seems difficult to imagine the vector of gravitational pull of Antarctic ice mass significantly affecting the South Seas on two grounds.
The mass of ice in the Antarctic which is actually increasing,would presumably attract more water towards the South Pole, reducing the level of sea water further away from it.
Even with ice accretion at the Antarctic you would think that the variations in the circulation of the core of the earth would make this incremental change just noise in the measurement of local gravity.
“while some polar regions will actually experience falls in relative sea levels”
…..then that wouldn’t be called sea level rise, would it?
“The model shows that parts of the Pacific will see the highest rates of rise”…..
….Most Pacific islands are sinking (subsiding). It is the usual fate of islands formed in oceanic settings that, when they come to the end of their active (volcanic) life they cool down and move into deeper ocean waters….
http://books.google.com/books?id=E8DEhXra8CAC&pg=PA26&lpg=PA26&dq=pacific+subsiding&source=bl&ots=sBLCJYA1R-&sig=fawp9w06CWiix06yFVH5I7oH3Ik&hl=en&sa=X&ei=PRgmUYOEIZOM9ASLzoH4Dw&ved=0CEgQ6AEwAw#v=onepage&q=pacific%20subsiding&f=false
Variations in subsidence rates along intermediate and fast spreading mid-ocean ridges
The most notable region displaying unusual behaviour is the East Pacific Rise between 9°S and 22°S. In this region, the western flank of the ridge is subsiding at 200–225 m Myr−1/2 while the eastern flank is subsiding at ‘normal’ rates of 350–400 m Myr−1/2
http://gji.oxfordjournals.org/content/87/2/421.refs
Batman’s Hill in Melbourne was leveled for the railway in the 1850’s. A 18 meter high steel marker shows where it stood. The Australian Bureau of Meteorology has its headquarters at 700 Collins Street which is, as most of Docklands, 2 meters above sea level.
I assume being on level 5 of the building means they will survive the modeled rise/rate of rise /sarc.
My old dad used to say – “Don’t listen to what folk say, look at what they do.”
“Thirdly the sheer mass of water held in ice at the frozen continents like Antarctica and Greenland exerts a gravitational pull on the surrounding liquid water, pulling in enormous amounts of water and raising the sea-level close to those continents.”
?? – Ice has less mass than water so it should be the other way round? Anyway plate boundaries that are coastal and have been crumpled such as the West coast of the US have considerably more gravitational mass than the Greenland Ice sheet as is evident by the lack of buoyancy of rocks. Therefore any coastal region that has above average mass for a plate should be pulling in more ocean. However, I would have thought the twice daily tides caused by the moon and the winds that circulate the Earth would get in the way of what would be a slow redistribution?
Aw come on guys, they’re using “sophisticated” computer modeling! That makes it so much more reliable and accurate when you bother to label it as sophisticated.
Just remember the root of that word, “sophist.” That should clue you in to the level of deception involved when engaging with the fanatical warmistas.
I read the following:
So I ask myself how did the Pacific basin respond during the warmer Holocene Climate Optimum?
How did the Polynesians respond during the Roman Warm Period?
How have the coral island atolls responded in recent decades to rising sea levels?
Nigel Harris – Your ham-handed sarcasm is noted. In rebuttal I would make the point that any scientific paper that says “our sophisticated computer models show…” isn’t worth a carrot and you don’t need to be a scientific genius to know that.
Furthermore scientists wrongly assume that applying the scientific method to any question will yield the true answer. Often it is better to look around you and discuss your observations with others who have also looked around. The conclusions you reach will most likely be a close match to reality.
I live by the sea (Holyhead, Wales) and have not observed any sea level rise. My friends and acquaintances, who include a marine engineer, a ship captain, a coastguard, and a port controller, are also of the opinion that there is no discernible rise in the sea level either here or , the other side of the Irish Sea, in Dublin.
Why would we even bother to listen to an academic with a computer model ?
Anecdotal evidence is very useful sometimes. If you heard gunshots and somebody, wide-eyed with fear, ran up and told you there was a gunman on the loose taking potshots at people would you
A) Get the **** out of Dodge
B) Wait until a distinguished scientist has published a peer-reviewed paper on the situation.
???
I recently visited Hawaii. The Hawaiian Islands have numerous “fossil” shorelines indicating rapid changes in sea level in the recent geological past. I visited a couple.
From “The Roadside Geology of Hawaii” page 235
“North of the old sugar mill at Kahuku, southeast of milepost 14, look for a hardened bed of pale boulders and patches of ancient reef rock seaward the highway. The is an old shoreline 25 feet above sea level. An old reef on the brushy slopes inland is about 100 feet above sea level. They apparently formed when sea level stood high between the ice ages.”
A hundred feet! It kinda puts a potential 60 cm rise into perspective.
As one who is following our sun’s rapid decline of activity; I would ask what the models show for ice growth with a drop of world temps into the next minimum? Mankind has much more to fear from the next “Little Ice Age”, massive death tolls from crop failures of the Irish and Scots come to mind. Let’s hope the Bond cycle doesn’t sync with this current pattern or a major volcanic event occurs.
Scute says:
February 21, 2013 at 3:47 am
You should add to just that fertile crescent aquifer water being extracted worldwide. Google “Cubic Kilometers” “Fossil Water” – you will find that at least 3 times as much ground water is being extracted elsewhere and returned to the water cycle increasing sea level. Libya, Saudi Arabia and even Texas.
If the paper is available outside a paywall it would be interesting to compare the actual amounts of liquid water in cubic kilometers from ice melt in comparison to deep aquifer releases.
How is the IPCC’s temperature projections turning out? They spent their careers making their projections and they were WRONG.
Perhaps you can:
like fuel poverty, homelessness, hunger, over-fishing, malaria, pollution, maternal health………………………. instead of focusing on gas phantoms of your own making.
Lubos Motl has an article written a couple of years ago relating ice loss and sea level decrease near Greenland.
http://motls.blogspot.com/2010/06/if-greenland-melted-sea-level-in.html
Rockhound says:
February 21, 2013 at 5:36 am
I recently visited Hawaii. The Hawaiian Islands have numerous “fossil” shorelines indicating rapid changes in sea level in the recent geological past. I visited a couple.
==================================
Fair enough. However keep in mind that the Hawaiian Islands aren’t the most tectonically stable place on the planet. While the more Northwesterly Islands are certainly sinking (IIRC, the most northwesterly volcanic outcrop still above sea level is about 1000 km NW of Oahu), that doesn’t preclude areas closer to the hot spot rising or falling due to activities in the crust/mantle below them.
On my list of things to look into is why there are not all that many wave benches and elevated coral reefs in areas thought to be tectonically stable. If you pick some coral islands at random and can find their maximum elevation it’s most often only a few meters. Seems like if ancient sea levels were higher, there should be elevated reefs everywhere coral islands exist.
Erosion, maybe.? It’s a puzzlement.
BTW, I think some Pleistocene deposits in the islands have been reinterpreted as tsunami debris, but that doesn’t sound likely for the one you visited.
Stephen Skinner says:
February 21, 2013 at 5:09 am
“Thirdly the sheer mass of water held in ice at the frozen continents like Antarctica and Greenland exerts a gravitational pull on the surrounding liquid water, pulling in enormous amounts of water and raising the sea-level close to those continents.”
?? – Ice has less mass than water so it should be the other way round? Anyway plate boundaries that are coastal and have been crumpled such as the West coast of the US have considerably more gravitational mass than the Greenland Ice sheet as is evident by the lack of buoyancy of rocks. Therefore any coastal region that has above average mass for a plate should be pulling in more ocean. However, I would have thought the twice daily tides caused by the moon and the winds that circulate the Earth would get in the way of what would be a slow redistribution?
======================
Mostly, I think you’re right, however their point seems to be that the Antarctic and Greenland icecaps are piled on top of (largely) land surface and add to its gravitational attraction on the surrounding ocean. If the icecaps (partially) melt you get additional water in the oceans, plus isostatic rebound, plus a change in the gravitational attraction. I have trouble believing the latter is significant, but I don’t have numbers to back up my gut on that.
You are aware that the sea isn’t really level? The deviations are small. but measurable and are, I’m assured, used in roughly mapping sea floor geography. Presumably, they have been confirmed by sonar. I read recently that seamounts only a km or so high can be identified and mapped using sea level variations. Static Variations in sea level due to sea bottom topography, wind patterns , rotation are NOT the same thing as sea level changes due to ice melt, runoff, glacial isostacy, tectonics. Sometimes folks have trouble keeping that straight.
A competition!
Opening sentences that make you stop reading.
“Sophisticated computer modelling…” is my early favourite.
Don Kay says:
BTW, I think some Pleistocene deposits in the islands have been reinterpreted as tsunami debris, but that doesn’t sound likely for the one you visited.
=================================================================
Yes several of the islands have coral debris from tsunami events high up on their shores. The book differentiates between the two.
I didn’t visit Lana’i , but “Roadside Geology of Hawaii” has this to day about fossil beaches at Shipwreck Beach and Reef:
“Fossil burrows are abundant in the layers of coarse calcareous beach rock that must have accumulated when sea level was higher than it is today. The layers slope gently seaward as they do in modern beaches”
“The exposed beach rock indicates that the sea level must have been higher in the recent geologic past, possibly 150,000 years ago. If Lana’i is sinking, why is the beach rock exposed? Sudden changes in global climate force rapid waxing and waning of polar ice caps and consequently, of sea level. In comparison, the rate of isostatic sinking is very slow. Lana’i is [not] sinking fast enough to drown the beach rock yet”.
That last line should read:
“Lana’i isn’t sinking fast enough to drown the beach rock yet”.
A couple of years ago I was at a lecture where the speaker (who has since become a “celebrity TV Scientist” favoured by the BBC) claimed that due to the developed countries of the Northern hemisphere building so many reservoirs the impounded water had caused a ‘bulge’ and affected the Earth’s spin and gravity . . . and hence the climate!
I wonder if that was factored into the models?
More to the point is such a claim feasible?
I like these scientist who use modells. Theiy always get the answers they want.
I find the entire premise of the paper dubious to the extreme, unless the “differences” they are talking about in SLR around the globe are on the scale of mm, a cm at most. The ocean is in a state of isostatic balance. Granted that there are inhomogeneities in the Earth’s mass distribution and that the surface is actively but slowly deforming, the planet is still a set of nested equipotential surfaces, and, allowing for the fact that the Earth is a rotating frame and the ocean is in a state of constrained dynamic flow, the surface closely oscillates around a single equipotential equilibrium because to the extent that it does not creates a fast store of energy driving it back towards equilibrium.
The idea of “uneven” SLR is something of a myth. There can be uneven subsidence of the ground, uneven uplift of the ground. There could in principle be alteration of the oceanic conveyor belt, real changes in ocean currents that affect how water piles up a bit here or there as its temperature and salinity change, although only the gods know how or if that sort of thing will happen in a circulation that we cannot really fully explain or predict anyway with chaotic and strongly coupled nonlinear aspects anyway. There could even be (as the article somewhat absurdly asserts) changes in local gravitation, again more or less impossible to predict because they have to be predicated on dubious predictions or understanding of how those changes will occur. All put together, we’re talking deltas of millimeters, not tens of centimeters, because the ocean is powerfully isostatic.
I could be mistaken about this — to be certain I’d have to look at the numbers and assumptions — but it does sound a bit doubtful that this is something to actually worry about. It is safest to say that when this year’s SLR of 3 whole millimeters occurs, it will occur pretty much uniformly all over the world’s oceans, within noise and some equilibrium decay times, and that if one smooths (coarse grain averages) SLR over a decadal time scale, it is uniformly distributed all over the planet within around 0.1%, or a millimeter per meter of rise.
rgb
Co-author Jonathan Bamber, of Bristol University, says, “This is the first study to examine the regional pattern of sea level changes using sophisticated model predictions of the wastage of glaciers and ice sheets over the next century.”
Gotcha!!! Pocket OED, 1925: Sophisticated, to spoil the simplicity or purity or naturalness of, corrupt or adulterate or tamper with.
Seems familiar, when will they ever learn? 😉
A few years ago took the UN’s numbers for groundwater irrigation and applied that amount of water to the oceans. Of course it won’t all end up there, but as a matter of perspective towards the 3mm SLR we see annually, the amount of water used for irrigation each year is the equivalent of 2.2mm SLR.
Odd conclusions.
See, the ever-larger “ice masses” in central Greenland and interior Antarctica are laying on top of two very different geologic structures.
In Greenland, the interior of the island (the bedrock) has been forced DOWN by the weight of the ice about it. So, from west to east, looking at a cross-section of the island, you see:
a very short very steeply-rising coastal mountain range with typical Alpiine glacier. Very short, very narrow, very steep glacier-cut valleys. The glaciers are < 40-60 km long (sea edge to tp of mountain), perhaps 50 meters thick (if that much where they hit the ocean's water)), and very narrow (1 km to 2 km wide) at the mouth. Remove Greenland's ice, and you'll see Norway's fjord's and valleys. But bedrock (the mountain tops) is visible on these mountains. The ice doesn't "cover" the tops of the coastal ranges, and the interior ice mass doesn't "flow" over the coastal ranges "into the sea." Rather, the coastal glaciers -like mountain glaciers anywhere, gradually gets less and less thick until, at the top of any typical Alpine glacier, the ice vanishes and the bare rock appears. New snow and ice falls, it presses down on the relatively steep slopes of the upper glacier, and pushes the accumulating masses DOWN towards the interior or DOWN towards the sea. Glacier ice thickness increases as the glacier length increases (always pushing down towards the sea) until there is a more-or-less balance between the resistance of the rock below the glacier, the mass of ice below the specific point pushing back uphill, and the weight of ice above pushing down.
At the interior of the Greenland island, the accumulating ice is higher than the exterior mountain ranges (3000+ meters) – BUT the interior bedrock is LOWER than sea level. The interior ice has pushed down the sea floor rock AND the continental crust BELOW sea level. If all of the interior to melt – before the sea floor rock and crust rebounds – you'd see a very narrow "belt" of coastal mountain ranges around an interior sea about 1000 meters deep.
Now, one very strong argument against blindly accepting the GRACE satellite "studies" that claim to have found massive Greenland ice losses is the simple problem that the GRACE space studies don't know how much the interior bedrock has dropped, how fast that drop has occurred, what the original levels were at any given time, and what the recent changes have, and what they will be. For example, we KNOW by measurements of teh WWII airplanes that have been found covered by 300 feet of new ice and snow that the interior ice mass has gotten thicker in the immediate 70 years. (Airplanes cannot "sink" into the ice because their wings and fuselages keep them "floating" – and ice above the airplane wing has been deposited (and not melted off) sicne the aircraft landed.) But, how much has the interior bedrock dropped due to that weight? How much resistance (lag time) is there between a deposition of say 10 gigatons of ice and the lowering of the bedrock? What is the net change in weight of the island as ice lands in the interior and pushes down the bedrock, and what is the "rise" in the caostal mountians from that push down in the interior? There have only been TWO measurements of the interior rock levels in Greenland. The second interior core drilling, I understand, failed. Thus, we have no history of Greenland's bedrock levels, no baseline for knowing if it is going up or down, and no historical knowledge to declare it is going up (or down) any faster or slower than it has ever gone up (or down) before.
Nor do we have interior top-of-ice measurements over any long enough period to really know what the ice cap is actually doing? Other than the aircraft "ice deposits" from 1940-2012, and the frequent "cover-ups" of new ice and snow over Cold War radar and meteorlogical sites and radio towers, we don't know the change in relative heights of Greenland's ice either: But, do note that NO Greenland "relative ice measurement" (like buried towers or buried DEW station domes) shows ANY station becoming "less covered with ice" over the past 60 years. So, ice appears to be accumulating whereever ice is found in central Greenland. (Coastal glaciers – all very short and very narrow) may or may not show changes.)
Thus, even though GRACE believes it is correcting for bedrock movement by measuring with GPS the TOPS of the coastal mountains (which are going up) are they not really correcting for bedrock changes in the interior (600-800 km away) by assuming that – “if the tops of the mountain ranges around Greenland’s interior ice mass are going up, then the bottom of the bedrock between the mountain ranges must also be going up by the same amount”? That assumption is, by the way, the only justification for declaring there is any loss of Greenland’s ice cap.
Could an increase in hieght of the coastal mountian ranges (becasue the interior ice is pushing down the central bedrock) cause an increase in nearby ocean water? Well – think about it and run the numbers. The central weight goes up due to an increasing ice mass of 100+ meters , the middle of the island gets heavier, the center rock goes down, the edges of the island go up (by 1 or two meters? 10 or 20 meters???) , the mountain slopes get steeper (by 1 or 2% ??) and the coastal glaciers get accelerated by a 1 – 10% so melt faster ?) and therefore the nearby ocean waters get “attracted” to the Greenland coast. (By 1 mm? 1/10 mm?)
At what time do these “scientists” stop waving their hands and actually look at the numbers they are extrapolating about?
We have CAGW extremists claiming in the classroom and on TV and in front of Congress that “hotter climates” casued more water vapor caused more storms like Katrina and Sandy.
But actual global and regional temperatures in September 2005 and in October 2012 WERE NOT HIGHER than earlier by measured amounts that could cause such a storm. October’s 1/5 of one degree higher global temperatures could NOT have caused the effect that the CAGW extremists want for their future grants and salaries. Need for their political purposes. Desire for their religious fervor to cut energy supplies to the world’s population.
“The BAS does some good science, especially in geology, but some of their claims are out of the mad box or reported before any real analysis of the data. Another model based claim probably using a model that assumes that glaciers are all melting etc. ”
You have misunderstood what they did.
1. There is no “real data” about what will happen if ice melts in greenland and antarctica. To understand what will happen you have to model it. you cannot run the experiment to see.
2. This is no different that modelling what would happen if a asteroid hit the earth. You put in known physics. you see what your best science predicts.
3. The Hypothetical is this: ASSUME that the ice melts. Then answer the question
A) where will the water go.
There are three ways to answer this question. ASSUME the ice melts. I know you think it wont. but, THIS exercise asks you to put on your curiousity hat. What if?
What if the ice melts. can you predict or make an estimate about the sea level rise?
Three answers.
1. we cant know
2. Errr figure out what that ice volume translates into water volume, spread that water
equally over the globe.
3. Err we know that just spreading it equally is wrong because our best science say that
gravity plays a role and rebound plays a role.. So, try to use what we know to calculate
A BETTER ANSWER than #1 ) I dunno. or #2) the water spreads equally.
Only here at WUWT would people not get that climate science is not a lab science. We dont get to melt greenland and measure where the water goes. Duh. We know that IF it melts that since that ice is “landed” the amount of water on the planet will increase not decrease.
We know that the first order answer — the water spreads evenly– is wrong, but its better than #1 which is just ignorant. So the best we can do is REDUCE the wrongness of #2 by using the best science we have. Not perfect science. Not settled science. Just the best we have
If I’m not doing this simple math wrong, the gravitational force exerted by the Greenland ice on objects within a few thousand kilometres is basically the same order as that exerted by the moon. Somebody feel free to point out my error – not like I compute gravitational forces regularly or anything…
If this is correct:
Mass of greenland ice: 2.67 x 10^18 kg
Mass of moon: 7.35 x 10^22 kg
Distance earth to moon: 3.84 x 10^8 m.
given F = g x m1 x m2 / (r^2),
then for any unit mass m2, the force between the moon and m2 is:
(6.67 * 10 ^ – 11) * (7.35 * 10 ^ 22) * m2 / (3.84 * 10 ^ 8)^2 = 12.77m2 * 10 ^ -5 N.
where for Greenland ice, lets take an r of 5 x 10^3 km for the sake of argument:
(6.67 * 10 ^ – 11) * (2.67 * 10 ^ 18) * m2 / (5 * 10^6) = 3.56m2 * 10 ^ -5 N.
I wouldn’t-a-thunk-it, but that’s what the math looks like. Note that I’ve made no argument regarding what this does to sea level, was just trying to get a feel for the plausibility of scale of forces here.
Here is a new sea level curve that may be of interest:
Figure 2 in: http://rockbox.rutgers.edu/kgmpdf/09-Wright.GlobalPlanet.pdf
Late Pleistocene Sea level on the New Jersey Margin: Implications to eustasy and
deep-sea temperature
Wright, et.al 2008 in Global and Planetary Change 66 (2009) 93–99
It is a time-reversed X-axis, today at left, 150 ka at right.
What’s with the anthropomorphising of sea level? Fingerprint?
… sea-level variations (fingerprints) …
if ‘fingerprints’ means ‘variations’ what’s wrong with using ‘variations’ throughout the paper?
I suspect a pathetic attempt at ‘climate communication’.
uhm, screwed up the Greenland ice computation a bit there. ~grin~
(6.67 * 10 ^ -11) * (2.67 * 10 ^ 18) * m2 / (5 * 10 ^ 6) ^ 2 = .71 * 10 ^ -5 = 7.1 * 10 ^ -6 N
Still sort of surprising to me.
You are aware that the sea isn’t really level? The deviations are small. but measurable and are, I’m assured, used in roughly mapping sea floor geography. Presumably, they have been confirmed by sonar. I read recently that seamounts only a km or so high can be identified and mapped using sea level variations. Static Variations in sea level due to sea bottom topography, wind patterns , rotation are NOT the same thing as sea level changes due to ice melt, runoff, glacial isostacy, tectonics. Sometimes folks have trouble keeping that straight.
Agreed. The deviations are small but measurable and nearly static as sea floor topography is a very, very slowly varying function. Nevertheless, the areas of the tectonic plates underlying the oceans and continents is very large, so even small changes as the plates move around can have significant effects on overall ocean level or its apparent depth relative to the local land surface.
I like the way you separate the “local” changes from global ones — overall SLR is driven by average temperature (thermal expansion), the melting of land based ice, and tectonics, where the latter is, I would guess, spectacularly difficult to accurately measure or estimate as it would require a detailed measurement of the precise location of the Earth’s crust in some absolute coordinate frame. We can probably manage that for the land surface at this point, but I’m infinitely dubious about our ability to do so for the ocean floor. Locally, water may pile up a bit more or less here or there as the decadal oscillations vary and oceanic currents wander around or local changes occur in topography that are somehow distinct from the more global tectonic changes, but they have very little global effect in SLR and are at most small perturbations of the globally varying level.
There is a large energy cost to making the ocean surface deviate too much from a coriolis-corrected gravitational equipotential. It’s an open system with heat inputs and outputs, so it can self-organize to sustain small deviations as water warms and expands in one place SO that it provides pressure gradients driving currents to someplace else, but most of that stuff is well-established and stationary too. Predicting changes from this stationary behavior is second or even third order stuff, and my gut says that the changes will be very, very small compared to those associated with direct thermal, melt, or tectonic/volumetric effects.
And I have a very hard time believing that we need to be terribly concerned about the gravitational field of the Greenland or Antarctica ice packs, given that it would take millennia to significantly alter the ice mass in either case even if it warmed significantly. We’re talking a lot of mass, all of it insulated by the mass on top of it. Also, there is that pernicious 1/r^2 in the law of gravitation.
rgb
rgb
Do the models tell us what the oceans will look like during the more likely scenario of increased glaciation?
We know that the first order answer — the water spreads evenly– is wrong, but its better than #1 which is just ignorant. So the best we can do is REDUCE the wrongness of #2 by using the best science we have. Not perfect science. Not settled science. Just the best we have
Which is perfectly reasonable. Of course a true cynic would note that it really is equivalent to making a hypothesis like “A gamma ray burst hits the Earth” or “Supposed the supervolcano under Yellowstone suddenly became active” or “the Earth gets hit by a 10 km asteroid” — things that are pretty unlikely but possible, in any short term time frame. Fun to think about, in a slightly twisted sort of way, but completely irrelevant to the climate debate even though in all three cases they would have enormous climate consequences.
Except that the results aren’t going to be presented as being completely irrelevant, are they? Nobody will bother to tell people that it would take a few thousand — or even tens of thousands — of years to melt the ice in Greenland or Antarctica, and that over the same time frame other changes would occur that would very likely make the “predicted” changes disappear into the noise associated with more important local changes (that themselves have to be predicated into the model or the icecaps won’t melt in the first place). Chances are good that people will take these predictions seriously as the basis of claims that the ocean is going to rise a lot here instead of there, and money will be spent to ameliorate a prediction of damage made on the basis of a model that even the modellers knew wouldn’t actually occur in a time frame relevant to contemporary human endeavor.
Many places are starting to spend money — in many cases a rather lot of money — to proactively prevent damage from a hypothetical rise of sea level that models predict will be as large as a meter or more by 2100. In the meantime the actual data for SLR shows that SLR rates have held approximately steady at less than 10 inches per century over the entire interval over which they have been measured, some 140 years. In order to reach the goal of a meter plus by 2100, the rate of SLR would have to more than triple, sustained, for the next 87 years, to order of a centimeter a year (which still wouldn’t do it, but would get close). At a whole centimeter a year, one would have decades to deal with the consequences before it became a serious issue anywhere in the world, and we haven’t the slightest actual evidence that it will reach a centimeter a year ever.
So the reason WUWT readers are less inclined to play the “nifty what-if science” game is because they see past the nominal result to the political subtext and the way the science will be distorted by those seeking to profit from exaggerated or misused claims. This happens all the time, right? Superstorm Sandy is evidence of climate change! So is Katrina! So is the latest major weather event, no matter what it is!
SLR is the single most important aspect of catastrophic climate change predictions. There is likely to be almost no net damage at all from global warming, anthropogenic or otherwise, especially if it takes place at a decadal crawl as it has for most of the last several hundred decades. Yes, patterns of rainfall and drought might change, but they change all the time anyway (see “Great Dust Bowl” or look at the paleoclimate evidence of drought distributions over the Holocene) and it isn’t likely that the changes we see will be qualitatitively or quantitatively particularly different than what we get naturally all the time. An argument can be made than on average the world would benefit from being warmer — it certainly has in all of the warm periods in the historical record.
No, the real argument for catastrophe is all SLR. If the ocean rises a meter or more in a century, it will flood a fairly predictable amount of shoreline and displace coastal or island residents. This has a computable, predictable cost, and that cost is very high because people like to live along ocean shores because of the climate and economic advantages to be found there. Take away SLR, and the “catastrophic” prediction devolves to egregious assertions of massive droughts or catastrophic superstorms, both of which are easily refuted by the actual data if one can just shut up the people that are openly lying about it in the political media.
Which is fine, but it makes SLR a politically crucial issue, because there is no cause for alarm in any possible mix of the gauge level or satellite derived SLR measurements! It isn’t that the ocean is doing alarming things, it is that we predict that eventually it will do alarming things. Maybe. If all the hypotheses and what-ifs that go into the models are right. If the water that melts in greenland or antarctica actually makes it to the ocean instead of just re-freezing (an instructive exercise is to compute the heat needed to melt all that water) and guestimate the time frame required for it to melt given surface to volume, albedo, and variation of surface forcing).
So when an article appears predicting the outcome of something that will almost certainly never happen, something that if it started to happen today might actually complete by the year 7500 CE, one does indeed have to be a bit cynical about whether or not it won’t appear in a lead article in some newspaper that is interpreted in just the right way to panic the residents of Patagonia or some island in the South Pacific into thinking that they mean that all of this is going to happen in the next thirty or forty years as that meter and a half SLR finally starts to happen.
rgb
uhm, screwed up the Greenland ice computation a bit there. ~grin~
(6.67 * 10 ^ -11) * (2.67 * 10 ^ 18) * m2 / (5 * 10 ^ 6) ^ 2 = .71 * 10 ^ -5 = 7.1 * 10 ^ -6 N
Still sort of surprising to me.
This isn’t a good estimate for an icepack, however, because the ice isn’t distributed in anything one could fantasize into a ball (as in the famous “assume a spherical cow” problem:-), but rather in a sheet that is always negligibly thin compared to its area. The correct estimate computation is to take a circular disk of mass and integrate to find the total field at a point on the rim and/or at points past the rim. I’m too busy to do the calculus right now, but it probably isn’t too difficult in plane polar coordinates (certainly easy if one has a handy quadrature program in e.g. matlab or octave). Maybe I’ll do it later if I have time during recitation or while administering an exam this afternoon. It’s tricky because the mass now varies with r^2 AND the field varies with 1/r^2, which makes both the geometry and scaling difficult. With ball it is simple — the mass scales like r^3, the field of the mass like 1/r^2, so the net variation is linear in r. I think that means that your estimate above is too high, but I’d want to do the computation before swearing to it as it is easy to guestimate wrong.
rgb
We need to take a very realistic view of these (very distance future! as RGB pointed out above ) “potential” sea level changes based on those very real-today-near-instananeous sea level changes we do see.
Lunar tides lift the sea (at mid-ocean) by tens of centimeters every hour every day. The tidal “lift” occurs every day, twice a day, and will level-out the world’s oceans accordingly. (By the way, does the actual mass of ocean water actually “move” around the world, or does it really only get-lifted “up” towards the moon and sun by becoming slightly less dense directly under the moon each hour so that the surface of the ocean water moved up relative to the “perfect sphere” we measure tide heights against? Something to think about.)
A river’s floods (the Mississippi-Missouri for example) greatly lift the river’s water level up at New Orleans by tens of feet each spring, which then will lift the Gulf of Mexico by tens of millimeters near the river mouth, and the edge of the Gulf by 1/000 of a millimeter. But that level then goes back down again in the days after a flood.
The Med is lower than the Atlantic measurably due to the water evaporating from it each day that is replaced by the currents flowing past Gibraltar. But the net height of the Med does not change year-to-year.
Near instantly, a tidal wave (tsunami) will lift the ocean surface by tens of centimeters – the rise moving at near the speed of sound in water across thousands of kilometers. But that rise is also dropped just as fast. So you can prove that short-term changes in ocean height are meaningless – they all go right back down again just as fast as the immediate cause goes away!
This then allows a near-permanent ocean “hill” to be measured over sea mounts, near coasts, or around Greenland or the Antarctic. Day-to-day transients “wash” right over the permanent rise in sea level caused by gravity. IF – and a very big “if” is there! – there were any change of 1/1000 inch in Greenland’s “gravity mass” it would be balanced out by the movement of water around Greenland within 12 hours – the next 12″ tide would go up by 12.001 inch and retreat 12.000 inch to match the change.
More accurately, as at Baytown TX and in Japan and in the San Franciscan Bay and the Everglades when ground water was pumped out, the apparent ground level will drop 2 meters in 10-20 years, then promptly go right back up again when water is restored by aquifers or by pumping replacement water back down.
Thank you R A Cook. Well writen and well thought out.
Nothing in concrete so to speak.Lets a person to jump
to his/her own conclusions.Thank you much!
Alfred
rgbatduke says:
February 21, 2013 at 9:38 am
…
This isn’t a good estimate for an icepack
———————–
Yup absolutely. Just a quick glance between meetings. I agree that treating a 1000 by 2000 km chunk o’ ice as a point mass for estimating gravitational forces at 1000 km scales isn’t a very satisfactory way to go.
I wonder if I could still do that integral.. It’s been awhile. Probably be a fun exercise later while waiting for my kid at hockey.
TinyCO2 says:
> Roman London can be between 6 to 8m below the current city street level.
Street level has nothing to do with sea level. Archeologists always have to dig for their data; as a rule, the older is the epoch of their interest, the deeper they have to dig. Why is that so?
There are two effects co-operating to push things underground. First, on a long enough time scale, active soil acts like a fluid. There is convective transport of matter in soil, due to worms and insects burrowing, plants growing and water flowing. Dense objects sink. Put a cubic foot of concrete out in your backyard and see how much it will sink during the next 30 years. I predict anywhere between 2 and 6 inches in temperate climate.
The second effect is soil forming. It combines dust accumulation with the fixation of atmospheric gases. You can’t have live soil without the surface level rising. Six metres in a couple thousand years is not a big deal. In London, in particular, there’s several extra feet of soil just from the human bodies buried there over time.
Mosh, the first two words are “We solve”…
Reporting in the journal Geophysical Research Letters researchers have looked ahead to the year 2100 to show how ice loss will continue to add to rising sea levels
unless somebody used a time travel machine to measure the future ice loss/temperature in 2100 they took the temperature data/projected melt from another model, one of those models that are already out of sync with the reality.
http://hockeyschtick.blogspot.com/2013/02/new-paper-finds-climate-models-are.html
http://hockeyschtick.blogspot.com/2013/02/new-paper-finds-climate-models.html
Turtles, turtles, turtles all the way down…
Religion did not change much.
Reality in the Pacific shows a different picture:
http://mclean.ch/climate/Sea_Level_Tuvalu.htm
http://hockeyschtick.blogspot.com/2013/01/inconvenient-truth-sea-level-rise-is.html
NOAA 2012 report too:
http://hockeyschtick.blogspot.com/2012/12/noaa-2012-report-finds-sea-levels.html
For our mid-range scenario, the ice melt component of total sea-level change attains its largest amplitude in the equatorial oceans, where we predict a cumulative sea-level rise of ~25 cm and rates of change close to 3 mm/yr from ice melt alone by 2100.
The average of tide gauges measure about 1mm per year which fits good with a minimal melting in Greenland, ice surplus in the Antarctica
http://mclean.ch/climate/Sea_Level_Tuvalu.htm
and depletion of “fossil water” on the continents which makes more then half of the sea level rise:
http://www.sealevel.info/
http://hockeyschtick.blogspot.com/2013/01/new-paper-finds-potential-glacier.html
I find the UC with the 3.2 mm/year as being the supporters of the expanding earth theory. If the seas measured by satellite raise in average 3 mm/year, but the seas in relation to coasts raise only 1 mm/year, it must be that the earth is expanding each year 4 mm (2 mm on each “side”). Hm…
[UC ? Mod]
Jeff says:
February 21, 2013 at 3:37 am
“Sophisticated computer modelling”… lost me right there …. how about rigorous
data measurement and collection….
*
Took the words out of my mouth.
Steven Mosher says:
February 21, 2013 at 8:17 am
Steve I see that you brought your straw man with you today.
Logical fallacy, how we love thee, let us count the ways:
straw man: “Only here at WUWT would people…”
false premise: “ASSUME the ice melts”
misdirection: “THIS exercise asks you to put on your curiousity hat”
appeal to emotion: “what would happen if a asteroid hit the earth. ”
appeal to authority: “using the best science we have.”
Q. Ever wonder what scientists did in ‘the time before computer models’?
A. They collected data.
Let’s giver it a try: From wiki (cringe), not my favorite source. “Summit camp est. April 1989. Originally a summer station only, the station had been manned year round since the early 2000s, with a winter population of 4 to 5.” (It is the ONLY station maintained in the interior. This biome represents 80% of the Greenland land/ice form. Translation: Every thing about Greenland is extrapolation and guess work. Short timeline for the database.)
http://en.wikipedia.org/wiki/Summit_Camp
“The climate is classified as polar, and the weather is highly variable and harsh. Typical daily maximum temperatures at Summit Camp are around −35 °C (−31 °F) in winter (January) and −10 °C (14 °F) in summer (July). Winter minimum temperatures are typically about −45 °C (−49 °F) and only rarely exceed −20 °C (−4 °F). Annual precipitation is about 3,000 mm (118.1 in), much of which falls as sleet or snow, which is possible in any month. Inland, the snow line in summer is at an altitude of about 300 m (984 ft). The highest temperature at Summit Camp was 3.6 °C (38.5 °F), recorded on July 16, 2012; the lowest recorded temperature is −67.2 °C (−89.0 °F).[6][7] In July 2012, satellite imagery showed there was an “unprecedented” melt of the Greenland ice sheet. In just four days from 8 July, the area of thawed surface ice grew from 40% to almost 97% of the entire ice sheet surface.[9]”
Translation: In July 2012 there was an anomalous 8 day warm excursion above freezing that maxed at 3.6 deg C. Typical daily max for July is -11 deg C. Excuse me but that is FREAKING COLD for July.
How about “What if pigs could fly”. Get real.
rgbatduke says:
February 21, 2013 at 9:19 am
Excellent post.
“This will affect in particular, Western Australia, Oceania and the small atolls and islands in this region, including Hawaii.”
I live in the faraway land of Western Australia and I’m sure our diligent investigative media are preparing tomorrow morning’s front page headline … “WA to drown before everybody else”.
We all know journalists scour WUWT for the latest climate change research (heh heh) and this one must surely satisfy the needs of our weekend press. Truth is that their lack of research skills means they’ll miss this opportunity for another sensational story, which is a good thing in a perverted way.
If I’m wrong and this nonsense does get media coverage, West Australians frantically preparing their life boats might wish to take a 20 minute break and read up on their local sea levels and land subsidence … http://www.waclimate.net/perth-sea-levels.html
Some notes from WUWT 5/16/2012 Is Sea Level rise Accelerating
Much of the thread was about conclusions about a study by Bruce Douglas using 23 tidal stations that Paul Homewood reduced to 12 stations to look for evidence of recent acceleration. What first caught my eye was the questionable geologic stability of the 12 sites, then how geographically clustered they were. Then, the noise apparent in the last decade of the records precluded any conclusion about acceleration.
Followed closely by May 28, 2012 4:45 pm that found an explanation for significant noise in tidal gauges.
So if there are current, temperature, and salinity factors that can distort the local sea level from the geode by 1000 mm, then what will it take to reject differences in rates of 1 mm/yr as just noise?
Steven Mosher says: February 21, 2013 at 8:17 am
Three answers.
1. we cant know
2. Errr figure out what that ice volume translates into water volume, spread that water
equally over the globe.
3. Err we know that just spreading it equally is wrong because our best science say that
gravity plays a role and rebound plays a role.. ….
We know that the first order answer — the water spreads evenly– is wrong, but its better than #1 which is just ignorant. So the best we can do is REDUCE the wrongness of #2 by using the best science we have. Not perfect science. Not settled science. Just the best we have.
Moser is of course entirely correct here. And it is an interesting exercise, as retreating sea levels at the poles would slow the melting of the Greenland and Antarctic ice sheets. Self regulation. Similar work carried out by Gomez: http://www.nipccreport.org/articles/2011/mar/16mar2011a4.html
But rgb (rgbatduke says:February 21, 2013 at 9:19 am) is correct too; this is only likely to occur over a large time scale that is full of other unpredictable events, that it becomes a bit pointless. It is simply an academic exercise.
Steven Mosher says:
February 21, 2013 at 8:17 am
After reading that well thought out and explained comment, my only question is … who are you, and what have you done with the real Steven Mosher?
Actually, my only difficulty is with #2, you say:
I make a very clear distinction between two classes or fundamental types of models—single-pass, and iterative.
Iterative models are harder to build, harder to get good answers out of, harder to debug, and harder to test and evaluate. This is because they are structurally different—an interative model takes it’s own output and uses it as input, eternally. The other makes one calculation and is done.
For example, F = M A, force equals mass times acceleration, that’s a model … and it’s a single-pass model.
A climate model, on the other hand, is an iterative model, hugely complex and difficult to debug, test, or understand the results of the tests.
So it is not true that a model is a model is a model, that F=MA is somehow equivalent to an interative climate model. There are fundamental structural differences. In particular, in a single-pass model a slight error is acceptable. In an iterative model, that error will often increase with each iteration … very, very different beasts.
In this case, they’re using an iterative climate model to determine what melts, with a weight-balance model to determine how the meltwater distributes. The weight-balance model is likely iterative as well, but of a much better sub-type. This type I call an iterative equilibrium model—it adjusts and recalculates the values until equilibrium is reached and then the process stops. I have no problem with that kind of model. Note that this differs from a climate model, which neither stops nor reaches equilibrium.
Having written and built and bug-tested a number of both iterative as well as single-pass models in a variety of applications and disciplines, I don’t trust (non-equilibrium) iterative models like climate models without serious testing. Particularly not this BS deal the modelers think is testing. I want proper verification and validation, like NASA does with any mission-critical software … with hundreds of billions of dollars at stake, not to mention the restructuring of the global economy, I am astounded that the AGW supporters are touting what by and large are home-made, crappily written, patched-together by a thousand un-documented kluges, untested, unverified, unvalidated trash software I wouldn’t trust to run my toaster. By and large the models are amateur hour on steroids, scientists aren’t programmers and it shows. And then the machine labors mightily behind closed door, and the portal opens, and they hand out three selected runs … what about the other 18 runs they left on the cutting room floor? What did those runs show?
How is that science in any sense?
THAT is my beef, not with models in general, but with the garbage that passes for programming and documentation, and the shocking paucity of validation, verification, and rigorous stress-testing of the modern iterative climate models.
I agree with you that we should do whatever we can to improve our ability to do “what if” calculations. On some tests, humans do worse than chimpanzees. This means that often the problem is not what we don’t know.
The problem is that what we do know is wrong … and that’s the difficulty with climate models. Many, many times they have been proven to be wrong, which leaves us doing worse than chimpanzees.
All the models showed a big temperature rise from 1995 to now, for example. People that believed and depended on that incorrect forecast rise lost whatever depended on it … and as a result, instead of what you want, which was
your model gives you A WORSE ANSWER to the question at hand, whatever it might be.
In other words, you assume the complex iterative computer model will outperform another model of continuation of the past, or a back of the envelope estimate, or other simpler methods, that it will give a BETTER ANSWER that whatever is in hand.
This year marks my 50th anniversary of writing computer programs, I wrote my first one in 1963. Me, I’ve seen stupendous computer model failures too many times to make any such unwarranted assumptions of a BETTER ANSWER … that’s the tantalizing siren call of computers that has lured many a good programmer to their doom.
Regards, and thanks for the interesting comment,
w.
I agree Willis. F=MA can be verified empirically so a good model.
My first bitch about this modeled ”research” is that these people stayed the warm indoors instead of doing some experiments in reality. Prof. Nils Axil Morner is a sea level expert. His research is based on measurement not model output. His reports can be relied upon to be very close to reality.
The one piece of research I have come across, from BAS, was a geological paper by a young PhD student who spent one whole summer on the icecap traveling hundreds of miles by skidoo to get rock specimens to prove her plate tectonic theory of where Antarctica was joined to Africa 100Ma ago. Good paper that was the culmination of months of work, travel in hostile conditions and near death falls into crevasses on the ice cap. That is what science requires at times and I felt honoured to have met this young lady just after her PhD was awarded.
Well, this confirms that the models were correct:
Quote from wunderground
Why care about Arctic sea ice loss?
If you remove an area of sea ice 43% the size of the contiguous U.S. from the ocean, like occurred in September 2012, it is guaranteed to have a significant impact on weather and climate. The extra heat and moisture added to the atmosphere as a result of all that open water over the pole may already be altering jet stream patterns in fall and winter, bringing an increase in extreme weather events. The record sea ice loss in 2012 also contributed to an unprecedented melting event in Greenland. Continued sea ice loss will further increase melting from Greenland, contributing to sea level rise and storm surge damages. Sea ice loss will also continue to crank up the thermostat over Arctic permafrost regions. This will potentially release a significant fraction of the vast amounts of carbon currently locked in the permafrost, further accelerating global warming.
http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2352
http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2352
1/5th of sea ice volume measured and confirmed the models were indeed correct since @1980.
Anyone who claims to be able to forecast the sea levels – or anything else for that matter – nearly a hundred years in the future is either a fool or a liar – or both.
Even if the climate models were ‘right’ it would still be impossible, the climate system is far too complex. The Met Office can’t even forecast the weather a few weeks in advance, for Heaven’s sake.
Obviously the climate models are not ‘right’, as almost certainly they are built on false assumptions, most notably that CO2 is by far the biggest forcing. All the models predicted warming that hasn’t happened, as clearly shown in the leaked IPPC report. I suspect that a model based entirely on red noise would actually do better than the IPCC models.
And yet these idiots think their models can predict the state of the world at the end of the century. Unbelievable.
Chris
Mark Bofill says:
February 21, 2013 at 10:14 am
rgbatduke says:
February 21, 2013 at 9:38 am
…
This isn’t a good estimate for an icepack
———————–
Yup absolutely. Just a quick glance between meetings. I agree that treating a 1000 by 2000 km chunk o’ ice as a point mass for estimating gravitational forces at 1000 km scales isn’t a very satisfactory way to go.
I wonder if I could still do that integral.. It’s been awhile. Probably be a fun exercise later while waiting for my kid at hockey.
———————————————
Mostly what I discovered last night waiting for my kid at hockey is that I definitely need a review of trig substitutions for integrations. I didn’t go polar coords (probably mistake #1 🙂 ) so I got stuck trying to integrate K((a^2)+(x^2))^-(3/2) where a goes 0 to whatever distance. To think I knew calc. in my youth. Oh well.
I find the UC with the 3.2 mm/year as being the supporters of the expanding earth theory. If the seas measured by satellite raise in average 3 mm/year, but the seas in relation to coasts raise only 1 mm/year, it must be that the earth is expanding each year 4 mm (2 mm on each “side”). Hm…
[UC ? Mod]
Appologies, CU … was thinking at “University of Colorado”
http://sealevel.colorado.edu/content/2013rel1-global-mean-sea-level-time-series-seasonal-signals-removed
Evie Jones says:
February 22, 2013 at 3:33 am
Well, this confirms that the models were correct:
Yes Jones, models confirm the same models, at least they are consistently biased.
Sea ice loss will also continue to crank up the thermostat over Arctic permafrost regions. This will potentially release a significant fraction of the vast amounts of carbon currently locked in the permafrost, further accelerating global warming.
Hm, I wonder, it did not release that vast amounts of carbon when it was significant warmer during the holocene or the previous interglacials, maybe because of the package is written : “punishment for human sinns, wait until anthropocene is called”? Or why?
Some keep on whining on Arctic sea ice loss at 80° and willfully ignore Antarctic sea ice gains at 60°, wonder why?
When you stay in a sunny day in winter on your feet in Alaska, do you get the same amount of solar radiation as when you lay on the beach in Mexico in summer?
In addition to this, have you ever saw light reflexibility on water graph, depending on the incident angle, or have these all been banned from wikipedia by our wiki-vigilantis?
The world is not flat as in the flat disc model with constant solar input.
Well -breathless pause- I’m certainly pleased to hear that they are using sophisticated compuetr modelling! I mean, who knows what kind of GIGO one might get if they used the un-sophisticated type?
Need I put /sarc?
“Don’t talk to me about Sifistication, Love — I’ve been to Leeds!”
TinyCO2 says:
February 21, 2013 at 4:05 am
…
New York was once a beautiful, mosquito plagued bit of swampy forest.
Maybe that’s why the Dutch handed it to the Brits in exchange for some Asian real estate.
Sea level rise – what’s wrong with just going to the waterfront and seeing how high the tide gets to?
O yes I forgot – SLR and AGW only happen where you cant see them.
BTW Arctic ice extent is still close to record in the last decade according to DMI and Norsex. Legacy warm water from the prior warming decades is flowing into a cooling Arctic, thus the abruptly higher summer-winter swings. We’re leaking heat at the pole big-time.
IF sea level rise is significant due to AGW, just as the 100-200 m SL changes at the beginning and end of interglacials are, then it is unnecessary to nit-pick about gravitational bulges. You notice it where-ever you are in the world.
So if it is necessary to nit-pick about uneven SLR to demonstrate an AGW effect on sea level, or revisit the past nostalgically to when real scientists measured gravity fields for fine-tuning ICBM navigation, then it means one thing very clearly: sea level rise or fall from AGW is NOT BIG ENOUGH TO BE SIGNIFICANT.