From the University of Southampton
A new study of satellite data from the last 19 years reveals that fresh water from melting glaciers has caused the sea-level around the coast of Antarctica to rise by 2cm more than the global average of 6cm.
Researchers at the University of Southampton detected the rapid rise in sea-level by studying satellite scans of a region that spans more than a million square kilometres.
The melting of the Antarctic ice sheet and the thinning of floating ice shelves has contributed an excess of around 350 gigatonnes of freshwater to the surrounding ocean. This has led to a reduction in the salinity of the surrounding oceans that has been corroborated by ship-based studies of the water.
“Freshwater is less dense than salt water and so in regions where an excess of freshwater has accumulated we expect a localised rise in sea level,” says Craig Rye, lead author of the paper that has been published in the journal Nature Geoscience.
In addition to satellite observations, the researchers also conducted computer simulations of the effect of melting glaciers on the Antarctic Ocean. The results of the simulation closely mirrored the real-world picture presented by the satellite data.
“The computer model supports our theory that the sea-level rise we see in our satellite data is almost entirely caused by freshening (a reduction in the salinity of the water) from the melting of the ice sheet and its fringing ice shelves,” says Craig.
“The interaction between air, sea and ice in these seas is central to the stability of the Antarctic Ice Sheet and global sea levels, as well as other environmental processes, such as the generation of Antarctic bottom water, which cools and ventilates much of the global ocean abyss.”
The research was carried out in close collaboration with researchers at the National Oceanography Centre and the British Antarctic Survey.
###
The full paper Rapid sea-level rise along the Antarctic margins in response to increased glacial discharge is published in Nature Geoscience.
Rapid sea-level rise along the Antarctic margins in response to increased glacial discharge
Craig D. Rye, Alberto C. Naveira Garabato, Paul R. Holland, Michael P. Meredith, A. J. George Nurser, Chris W. Hughes, Andrew C. Coward & David J. Webb
- Nature Geoscience (2014) doi:10.1038/ngeo2230
The Antarctic shelf seas are a climatically and ecologically important region, and are at present receiving increasing amounts of freshwater from the melting of the Antarctic Ice Sheet and its fringing ice shelves1, 2, primarily around the Antarctic Peninsula and the Amudsen Sea. In response, the surface ocean salinity in this region has declined in past decades3, 4, 5, 6, 7, 8, 9. Here, we assess the effects of the freshwater input on regional sea level using satellite measurements of sea surface height (for months with no sea-ice cover) and a global ocean circulation model. We find that from 1992 to 2011, sea-level rise along the Antarctic coast is at least 2 ± 0.8 mm yr−1 greater than the regional mean for the Southern Ocean south of 50° S. On the basis of the model simulations, we conclude that this sea-level rise is almost entirely related to steric adjustment, rather than changes in local ocean mass, with a halosteric rise in the upper ocean and thermosteric contributions at depth. We estimate that an excess freshwater input of 430 ± 230 Gt yr−1 is required to explain the observed sea-level rise. We conclude that accelerating discharge from the Antarctic Ice Sheet has had a pronounced and widespread impact on the adjacent subpolar seas over the past two decades.
===========================================
Fortunately, they provide an SI file, seen here: http://www.nature.com/ngeo/journal/vaop/ncurrent/extref/ngeo2230-s1.pdf
Figure S4 is telling:
It seems there is a “pause” that has developed in SLR around Antarctica starting around 2005 continuing through 2012.
For reference, this map from NOAA/NESDIS shows that there is in fact about 2 cm of SLR around some parts of Antractica, but the main SLR is a big red patch in the Western Pacific:
While the Rye et al. paper says ice melt from the continent is the cause, it may also be simply a matter of winds. Note that the red spotch of SLR on the map above is mainly an issue of winds and ENSO. Around Antarctica, we have a strong circumpolar wind pattern, as is seen in the video below about ozone over Antarctica:
That circumpolar wind pattern around Antarctica can act as a sea level rise enhancer, as described in this paper:
Rapid subsurface warming and circulation changes of Antarctic coastal waters by poleward shifting winds
Spence et al. 2014
Abstract
The southern hemisphere westerly winds have been strengthening and shifting poleward since the 1950s. This wind trend is projected to persist under continued anthropogenic forcing, but the impact of the changing winds on Antarctic coastal heat distribution remains poorly understood. Here we show that a poleward wind shift at the latitudes of the Antarctic Peninsula can produce an intense warming of subsurface coastal waters that exceeds 2 °C at 200-700 m depth. The model simulated warming results from a rapid advective heat flux induced by weakened near-shore Ekman pumping, and is associated with weakened coastal currents. This analysis shows that anthropogenically induced wind changes can dramatically increase the temperature of ocean water at ice sheet grounding lines and at the base of floating ice shelves around Antarctica, with potentially significant ramifications for global sea level rise.
Bottom line: I’m not much worried about the claims made about SLR in Antarctica being due to ice melt. There may be some enhancement, but to say it is the sole reason, when other fcators are clearly at play is just your typical climate alarmism at work.
UPDATE: Having written this piece late in the evening, my fatigue must have caused me to forget this graphic. Temperature over Antarctica seems to to be ever so slightly negative trending.
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So the fact that Antarctic sea ice has been rapidly increasing over the last few years has passed them by then? Or is it an inconvenient fact that must be overlooked in the name of climate alarmism?
I just read the abstract:
So is the hole in the ozone layer getting bigger or smaller?
If it’s growing then the cooling can be explained.
But it is getting smaller.
So I don’t think this paper sheds mush light on the matter.
Not much light though. The final paragraph reads (my emphasis):
‘We SPECULATE that the period through which we are now passing MAY be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects MAY instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, MAY continue to warm at an accelerating rate.’
Yet another hypothesis built upon the hypothesis that CO2 emissions MAY cause significant warming. The trouble is that the latter hypothesis has now gained the status of a faith.
“…while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties.”
The effect of ozone depletion is to let more SW ( UV ) solar energy enter the troposphere. Cooling stratosphere and warming oceans.
http://climategrog.files.wordpress.com/2014/07/tls_icoads_70s-20s.png
http://climategrog.wordpress.com/?attachment_id=988
Since UV penetrates to some depth it takes several years to heat the bulk of water. It appears from that graph that it takes 5 or 6 years to regain something like a stable level after a relatively step-like event of a major eruption.
The suggests relaxation response with a timeconstant of about 1.5 years to adjust to the new radiative balance. That would explain the delayed warming.
“We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals.”
Interestingly, this paper takes a similar approach of using step functions that I have used in looking Mt Pinatubo effects, so is talking the same language. Looking at their figure 3 , the ozone step response of the MIT ocean only model takes about 20y to settle.
Three of four time longer than what I found in SH SST response to changes in global stratospheric ozone.
Looks like some of the “parameters” of the negative feedbacks in their model need tweaking.
I don’t think the sea ice is nearly as important as the AIS volume, which is declining. See Helm, V., Humbert, A., and Miller, H.: Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2, The Cryosphere Discuss., 8, 1673-1721, doi:10.5194/tcd-8-1673-2014, 2014
M Courtney says:
So I don’t think this paper sheds [mush] light on the matter.
Mush does not need light; it grows best in the dark.
Here is a crazy idea. Maybe the increasing ice, which is increasing mass, caused increasing gravity which caused increasing sea level.
Crazy if you are considering sea-ice which is floating and very thin, but very relevant to changes in the mass of the Antarctic icecap which have a considerable effect on sea-levels. A higher sea-level would suggest a thickening icecap, but of course that is an absolutely forbidden thought….
Not a so forbiden thought in a case of a decreasing sea lvl…..if by any chance there was or will be a reverse and a sea lvl decreament observed then the models will be showing that been due to the thinning and loss of icecap mass….and voila again AGW…..:))
For as long as there a model mentioned don’t be surprised while any thing possible under the sun is due to AGW.
As far as models concerned anything ever was, is and always will be due to AGW.
One thing these models got right though……never ever daring to piss off their “masters” by disagreeing with the expectation to support the AGW, anytime anywhere requiried……otherwise they get fried or tortured till they at last get it right… 🙂
It seems that my silly comment was not clear. The ice on the continent is increasing so the gravity of the continent would increase and like the moon pull more water toward it.
Gravity just isn’t that influential. However … increased ice over the continent would lead to isostatic changes (the continent sinks proportionate to mass gained and the plasticity of the mantle beneath. Increased mass also creates some really odd conditions beneath the ice cap where pressure leads to supercooled, high-pressure water (stays in the liquid phase), which is discharged from beneath the edges of the ice with interesting results.
So they call the poleward winds anthropogenically induced with no scientific evidence whatsoever?
The only anthropogenic cause they talk about is CO2 yet there has been no global warming for 17 years so how can it be causing the ice melt.
Also they talk about the Arctic warming faster than the rest of the planet hence the lack of Antarctic ice melt, now they expect us to believe that the antarctic is melting and the Arctic cooling.
Wow…just…wow.
I’m sorry, but a SL rise of 2mm (+/- 0.8mm)/yr for a period of 19 yrs results in a 3.8cm (+/- 1.5cm) rise. That means a maximum rise, along the Antarctic coast, of 5.3cm and a minimum of 2.3cm over that 19 year period. A claim that the SL rise is 2cm over the Global average is preposterous. If the Average Global SL rise over the same time period is 6cm, then the Antarctic SL rise has been 0.68cm less (at the maximum), and 3.72cm less (at the minimum) than the average and 2.68 to 5.72 cm less than what they are claiming – which is “fresh water from melting glaciers has caused the sea-level around the coast of Antarctica to rise by 2cm more than the global average of 6cm”.
Uh ho. 19 years!
But just yesterday we had this wonderful story on WUWT.
It’s a good thing these people aren’t on trial.
Mike Tremblay September 1, 2014 at 12:49 am
“I’m sorry, but a SL rise of 2mm (+/- 0.8mm)/yr for a period of 19 yrs results in a 3.8cm (+/- 1.5cm) rise. “
Rye et al say (in press release):
“A new study of satellite data from the last 19 years reveals that fresh water from melting glaciers has caused the sea-level around the coast of Antarctica to rise by 2cm more than the global average of 6cm.”
The abstract says:
“We find that from 1992 to 2011, sea-level rise along the Antarctic coast is at least 2 ± 0.8 mm yr-1 greater than the regional mean for the Southern Ocean south of 50° S.”
How is this inconsistent?
Look on the bright side; if the Antarctic sea level has risen 2cm more than the global average, somewhere else has risen 2cm less than the global average
Sorry about my ignorance, I always thought the Antarctic remained below freezing (I am aware the Arctic rises above). So, the temp DOES go above freezing – allowing ice to melt? Is that correct? Would someone be kind enough to answer?
So, please could they explain how the “ice sheets are melting”. Sublimation is possible by the application of a lot of sunlight , otherwise how in hell’s name does ice melt at -20 to -70°C ?
Marlow Metcalf
September 1, 2014 at 12:15 am
Here is a crazy idea. Maybe the increasing ice, which is increasing mass, caused increasing gravity which caused increasing sea level.
and the extra weight is making the land mass sink ?
Grace, don’t know what pile of …………… you appeared from but it has warped you mind.
“The recent Appell affair”
I have forgotten this or missed it. What is the “Appell affair”?
Fully agree.
markstoval
A character by the name of David Appell created a number of false persona who posted to a series of WUWT threads with the clear intention of causing disruption and destruction of discussions. Some of these persona were vary strange individuals and some acted in support of each other (well, in reality they were the same person).
The matter first came to light when Appell could no longer control his infantile glee and sent an email to our host which boasted what Appell was doing and said his purpose was to “mess with {our host’s} head”.
Richard
I agree, RSC. I think “troll” used be used with caution.
Marlow Metcalf says: September 1, 2014 at 12:15 am “Here is a crazy idea. Maybe the increasing ice, which is increasing mass, caused increasing gravity which caused increasing sea level.”
To have an increased sea level due to gravity would need, for the increased sea level to remain increased, lesser gravity in that area. Rather difficult to see how actual gravity could be reduced unless there is marked change in the earth’s mantle or core.
Increasing ice would have no effect – since ice floats, it displaces its own mass of water, therefore there would be only the minutest effect on local gravity due to the mass of ice above the level of the observer (or since the observer is up there but is calibrating it at sea level, the effect on general sealevel in the vicinity would be negligible other than edge of the iceberg.
However, since some of the tabular icebergs are massive, could this local reduction in gravity due to the mass of ice above sea level have caused a “local” increase in sea level which is being averaged out by the satellite to produce the anomaly?
Correct.
Actually the increased mass of a growing icecap does attract the water in surrounding oceans and pull up the sea-level. This effect is surprisingly strong and amounts to several meters for the entire Antarctic icecap. Actually this is a confounding factor in any historical measurements of sea-level near Antarctica since we don’t know changes in the local gravity field with any precision before GRACE.
Notable about the NOAA visualisation map are the large areas of grey near the poles. Presumably these mark the region where there is no satellite data.
‘A region which spans more than a million square kilometers.’
7% of the continent. Which leads one to wonder: How much is the rest of the continent GAINING in snow and ice accumulation?
Why is it we never hear the other half of the equation?
Maybe because of this (comment down thread).
Thanks Jimbo! ‘Not seen in 60 yers.’ Now Why does that sound like the signal of a cycle? *g*
Why does a simple paper like this need eight authors? It must have cost the taxpayers a fortune.
Obviously all eight of them needed funding!
Blamesharing.
Greater sea level rise in the western Pacific, where the trade winds drive the warmer less dense surface water in the equatorial pacific; who should be surprised, I’m not. After all it’s just basic high school physics.
Yes there is nothing new under the sun.
What’s the provenance of the NOAA mapping, and for what period? shows 6cm in front of my place. “Who should be surprised” – I am.
This may not be much but I think this would have been noticed.
Local measurements don’t seem to indicate anything. Longer term? Nada.
2 cm is less than an inch. Now just how far does the ice extend outwards from the shoreline and just how deep/tall is the ice both on shore and that floating over the sea?
There are other things to worry about such as paying the taxes to keep the CAGW grant gravy train rolling
How do we know that these observations are not demonstrating the combined effect of apsis and nodal rotation variations in the orbit of the moon on earth’s oceanic tides in the Antarctic?
“The melting of the Antarctic ice sheet and the thinning of floating ice shelves ”
These are the thinning ice shelves discovered by Chris Turney?
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ rescearch grants
I blame it on poor climate “science” communication. If Professor Turkey had known about this disastrous sea level rise, the Ship of Fools fiasco might never have happened.
Or it could have been not enough sad scientist faces, we may never know…
Oh geez, I could have done without that ugly vision in my head. I think I will go cut some grass, after I take a great big scientist and release a lot of methane
I dont know why WUWT gives any attention to this AGW drivel article and journal Once you see this
“amounts of freshwater from the melting of the Antarctic Ice Sheet and its fringing ice shelves” when it is blatantly obvious that Antarctic Ice sheet is freezing more (increasing) for the past 3 years. Check out CT today (a warmist site but has to show the data).
“While the Rye et al. paper says ice melt from the continent is the cause, it may also be simply a matter of winds.”
Rye et al says that salinity has reduced. Winds couldn’t cause that, nor sea ice changes. It needs a source of fresh water. Rye et al say 350 Gtons have been added.
“The computer model supports our theory that the sea-level rise we see in our satellite data is almost entirely caused by freshening”
That’s basically just an Archimedes calculation. Equilibration of pressure with the less dense fresher water.
Nick: what is the other half of the equation? How many gigatons are being re-deposited upon the continent?
Ummm… their error range is ~107% of their model’s calculated value. I’m not gonna give that freshening WAG much of a chance of being correct.
I thought it was a simple Archimedes calculation…..
Nick writes “Rye et al says that salinity has reduced. Winds couldn’t cause that, nor sea ice changes.”
Increasing sea ice can certainly change the influx of fresh water each summer. Over winter the water freezes and we can no longer accurately measure the sea level in the region under the ice of unknown thickness’s and furthermore the mixing over the winter months would homogenize the salinity in the region ready for the summer melt.
Lest you forget http://sunshinehours.wordpress.com/2014/08/31/antarctic-sea-ice-extent-aug-31-2014-still-climbing-still-setting-daily-records/ LOL
Decreasing Salinity could also be caused by increasing sea ice. Has the sea ice around Antarctica been inreasing?
I would have thought that increasing sea ice would increase salinity as the ice doesn’t dissolve so much salt – meaning the layer beneath the new ice is saltier?
Unless the flow of saline infused bottom water has increased? But where do they get the idea of thinning sea ice? I see this only in the area affected by geothermal forces. AFAIK, overall sea ice has increased quite dramatically and the majority of south pole SST have cooled slightly, and there has been no warming over the majority of Antarctica.
From wik…
Antarctic bottom water is formed in the Weddell and Ross Seas, off the Adélie Coast and by Cape Darnley from surface water cooling in polynyas and below the ice shelf.[2] A unique feature of Antarctic bottom water is the cold surface wind blowing off the Antarctic continent. The surface wind creates the polynyas which opens up the water surface to more wind. This Antarctic wind is stronger during the winter months and thus the Antarctic bottom water formation is more pronounced during the Antarctic winter season. Surface water is enriched in salt from sea ice formation. Due to its increased density, flows down the Antarctic continental margin and continues north along the bottom. It is the densest water in the free ocean, and underlies other bottom and intermediate waters throughout most of the southern hemisphere. The Weddell Sea Bottom Water is the densest component of the Antarctic bottom water.”
So yes, the surface is initially saltier, but this is cooled and more dense, so with more sea ice, more salt may be flushed down. Very cold very dense water.
Sea ice loses salt as it ages, at least as I understand it. The whole salinity issue revolves around a complex set of possibilities. The paper only really addresses one. And worse, no one seems to want to address the potential of these various processes acting together. The discussion of the formation of eskers related to the development of ice sheets here is noteworthy. The article is unfortunately paywalled.
http://www.sciencedirect.com/science/article/pii/S0277379108002539
The gist is that there are extensive water circulation systems beneath ice sheets and ice accumulation conditions have profound effects (in models anyway) one chemistry, circulation patterns, and a host of subglacial phenomena. The conditions and behaviour of water, ice and till beneath glaciers is “problematic.”
Setting records daily, to go along with record cold
http://www.antarctica.ac.uk/about_antarctica/teacher_resources/resources/factsheets/factsheet_geostats_print.pdf
Go to Google Earth and draw a piece of 1000km by 1000km in any part of the Antarctic Ocean.
Once the temperature reaches 4ºC , water begins to expand.
http://krhall.files.wordpress.com/2010/09/intermolecular-forces.pdf
So what we see is a cooling effect.
1 million sq km eh. Will their next study be to East Antarctica? We have had some extreme snowfalls there in recent years.
Perhaps it’s volcanoes under the ice. See http://joannenova.com.au/2014/05/that-west-antarctic-melting-couldnt-be-caused-by-volcanoes-could-it/.
Quite possible in areas at least.
funny..I always thought fresh water froze faster than salty, which is why we used a brine bath to make icecream.
so fresh “fluffy”?? water sits higher.
aww cmon.
You’re right, it does freeze faster, but, fresh water will float on top of brine until mixing equalizes the distribution of solutes in the water. That, however, takes time. Columbus found that out in the Caribbean in fact. They intended to fill water butts from freshwater pools on a limestone island. Dropping the buckets in as deep as they could, to retrieve the coldest water, they were shocked to find the water in the buckets was salt. His crew though they were being teased by demons. In fact the pool was open to the sea.
Around Antarctica the circumpolar winds and currents tend separate Antarctica from rapid interaction with the rest of the planet. That slows mixing between the water around and air over the continent and the rest of the world. So, if fresh water accumulation out-paces mixing and dispersion, you develop anomalous situations that are limited by the rate the water will disperse outward across the Antarctic circumpolar current surrounding the continent.