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.
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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.