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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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.
???