From the University of California – Irvine something that pretty well makes Steig et al 2009 even more irrelevant, since in that paper they did a survey of air temperatures and then smeared them around the continent using some Mannian style math, which was later shown to be faulty by O’Donnell et al.
UC Irvine found that ocean currents cause most of the observed melt, so air temperature really isn’t much of an issue.
Warm ocean drives most Antarctic ice shelf loss, UC Irvine and others show
Findings are a game changer for future forecasts about thawing continent
Irvine, Calif. – Ocean waters melting the undersides of Antarctic ice shelves, not icebergs calving into the sea, are responsible for most of the continent’s ice loss, a study by UC Irvine and others has found.
The first comprehensive survey of all Antarctic ice shelves discovered that basal melt, or ice dissolving from underneath, accounted for 55 percent of shelf loss from 2003 to 2008 – a rate much higher than previously thought. Ice shelves, floating extensions of glaciers, fringe 75 percent of the vast, frozen continent.
The findings, to be published in the June 14 issue of Science, will help scientists improve projections of how Antarctica, which holds about 60 percent of the planet’s freshwater locked in its massive ice sheet, will respond to a warming ocean and contribute to sea level rise.
It turns out that the tug of seawaters just above the freezing point matters more than the breaking off of bergs.
“We find that iceberg calving is not the dominant process of ice removal. In fact, ice shelves mostly melt from the bottom before they even form icebergs,” said lead author Eric Rignot, a UC Irvine professor who’s also a researcher with NASA’s Jet Propulsion Laboratory in Pasadena. “This has profound implications for our understanding of interactions between Antarctica and climate change. It basically puts the Southern Ocean up front as the most significant control on the evolution of the polar ice sheet.”
Ice shelves grow through a combination of land ice flowing to the sea and snow falling on their surfaces. The researchers combined a regional snow accumulation model and a new map of Antarctica’s bedrock with ice shelf thickness, elevation and velocity data captured by Operation IceBridge – an ongoing NASA aerial survey of Greenland and the South Pole. (Rignot will host a planning session of Operation IceBridge scientists at UC Irvine on June 17 and 18.)
Ocean melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of Antarctica’s ice shelves, accounted for only 15 percent. Meanwhile, less than a dozen small ice shelves floating on relatively warm waters produced half the total meltwater during the same period.
The researchers also compared the rates at which the ice shelves are shedding ice with the speed at which the continent itself is losing mass and found that, on average, the shelves lost mass twice as fast as the Antarctic ice sheet did.
“Ice shelf melt can be compensated by ice flow from the continent,” Rignot said. “But in a number of places around Antarctica, they are melting too fast, and as a consequence, glaciers and the entire continent are changing.”
Other authors are Jeremie Mouginot and Bernd Scheuchl of UC Irvine and Stanley Jacobs of Columbia University. Funding was provided by NASA, the National Science Foundation, and the National Oceanic & Atmospheric Administration.
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“game change” – haha Rignot wrote papers on this years ago. Nobody actually thinks that air temperature caused the changes in Antarctica.
Tim Folkerts says:
June 13, 2013 at 7:54 pm
Desert Yote says: “What ever the reason, it has nothing to do with atmospheric CO2. “
It is always interesting to see people who are 100% sure of anything in climate science. Especially when pretty everyone else agrees that CO2 has some effect on the global temperatures.
“That would be like towing a semi-trailer with a moped.”
Or like towing a space shuttle with a pickup truck.
###
Yes, the 170,000 lb Space Shuttle is well within the towing capacity of that truck which was designed to tow. Your point?
“REPLY:
For example, here it is claimed that the Larsen B ice shelf collapse due to warming air temperature.
http://www.climatehotmap.org/global-warming-locations/larsen-b-ice-shelf-antarctica.html”
That article also talks about the influence of the warming ocean on the collapse of Larson B.
I would call it simple accuracy, or comparing apples with apples. The Cryosphere Today data is about sea ice, not ice shelves.There was no ‘comparison’ made, it was a simple mistake on the part of the poster. If someone wants to tie together these different components in scientific terms, then there is nothing to stop them. I simply pointed out that it was a different metric to the research. Isn’t it important to be accurate?
From the news article, it seems that primacy of cause has shifted to ocean warming, rather than air temps dismissed entirely. We’ll have to wait and see when the study comes out, otherwise we are at risk of overinterpreting the media release.
So Antarctic ice mass is decreasing, and the major contributor is warmer-than-before water circulating around it. Kevin Trenberth’s “missing heat” is melting the Antarctic ice (latent heat) instead of warming the surface and lower troposphere.
Sounds like global warming to me.
Well, pending confirmation that the Antarctic ice actually is melting (ice extent is increasing, but that isn’t perfectly proportional to mass), and assuming that the energy of the melt really does match the missing heat. The results, as reported here, do not contradict the main claim that increased CO2 is causing increased heat retention in the climate.
To back up my latter point, from the article:
Perhaps the other 45% of shelf loss is air temp related? We won’t know until the paper comes out.
It should go without saying that this is just one paper, and should not be hailed as definitive.
REPLY: “Perhaps the other 45% of shelf loss is air temp related?” Oh please, perhaps fairies are using the ice in flavored drinks. Just as plausible. This is one of the those moments I’m pretty sure you are just an SkS shill (since you live in Australia), and that you don’t understand how ocean-air interaction works. The peninsula has warmer air temperatures partly because of the warmer ocean currents, partly because of waster heat from the camps where the temperature is measured, something we covered in previous essay here at WUWT. Take a troll time out. – Anthony
dah!
I’m sceptical about warmer water causing ice shelf melt.
We know a lot ice has been lost from the Larsen A, B & C ice shelves, but all 3 are surrounded by sea ice that doesn’t melt in the SH summer. I find warmer air and warmer water unsatisfactory explanations (with a couple of specific exceptions covered below), because why aren’t they also melting the much thinner sea ice?
I can think of 3 reasons for the Larsen ice shelf melt
1. Increased Foehn winds, which have their greatest effect close to shore where the ice shelves are.
2. Decreased clouds. The ice shelves have rock particles embedded, whereas sea ice doesn’t. Hence they will have a lower surface albedo.
3. Increased warm water upwelling near the coast, and hence under the ice shelves. I don’t think this likely for a couple of reasons. Mainly, the sea ice close to shore between the ice shelves isn’t melting.
I think 2 is the likeliest, and essentially the same phenomena, embedded black carbon is melting the Arctic sea ice.
John of Okham would be happy.
The article is about floating ice shelves melting from underneath. Melting of floating ice should have only a minor effect on sea level. Fill a glass with ice cubes. Add water to the brim. Some will float. Does the water overflow when the ice cubes melt?
Trenberth’s heat is tied up in at least two missing variables, no worries.
And on that note, 60 percent of the Earth’s freshwater tied up in glaciers, wow, think about how many fracking wells that could facilitate or how many water bottles that would be…Makes my brown eyes turn green.
Hey, Larry Kirk, #[:)] (I was going to let you remain anonymous; thought you’d written a little more ambiguously than you intended and didn’t want to make a big deal about it). Well, good for you to step right up and own your own statement.
Apparently, the warming of the system remark was about rising sea levels and I misunderstood you.
(BTW, I have not seen any evidence of an overall, globally manifested, rise in sea level.)
Good luck with those mangoes! (hope it is, indeed, warm enough)
***************************
@ur momisugly Kajajuk — LOL. This site is fun. Apparently, in your part of the world, “Duh” is pronounced (and written: “Dah.” [or did you accidentally omit the “Ta?”]
In the U.S., “Duh” = well, that was obvious…
and “Dah” (usually with a few “aaa’s” added) would be used to make someone sound just plain stupid, e.g., “I’ve been to…. daaah…. 57 states… not …. uh… daaaaah… counting Alaska and Hawaii…. .” I WONDER WHO SAID THIS IN 2008? #[:)]
And, of course, from “The Simpsons” TV show,
“D’oh!” means basically — “Oooh, rats! I just messed up (or blew it)!”
John of Ockham would be a very unhappy climatologist.
D’oh!
Richard Hill says:
June 13, 2013 at 11:04 pm
———————————–
Interesting analogy, perhaps it could be improved with ice cube frozen to the lip of the glass and a 1,000 cubes adjacent to the ‘shelf’ cube; then the first cube melts as more cubes are added to the stack…
Yes. But ice shelves also impede the flow of land-based ice (they are extensions of land-based ice over the water), so as they disintegrate, more ice can flow off the continent, a point that the researchers make.
Larry Kirk says:
June 13, 2013 at 9:20 pm
I agree – although the CAGW climate boys would rather us consider the Earth as a closed system in order to point the finger at evil CO2. The long and short of it, is that the Earth is ‘isolated’ but not ‘closed’ with respect to fixed input and output of radiative energy. The minute but long term changes in incoming OR outgoing energy are what cause the major climate changes and that must certainly be considered as a ‘natural’ process.
Add in the undoubted time lag that it takes for such changes to affect the biosphere (how long at an extra 1 w/m2 would it take to heat up the ocean, even half a degree, a bloody long time, I’ll wager!) and it as clear as the nose on ones face that there is virtually no way to correlate any current measurements to recent changes. How long does it take for deep ocean water to circulate? we can only guess, but again, it will be a long long time. I find it simply amazing that these basic premises of time lags between cause and effect are absent in the majority of climate related publications.
Folk mention scale issues (moped and space shuttle, etc) but that’s just peanuts to the time it takes to warm an ocean IMHO ! A more accurate analogy might be trying to move/pull saturn using a moped! So, even though we ‘think’ we have warmer oceans based on our very limited temporal observations, we don’t see the moped – or at least the climate boys keep inventing it – CO2, AGW, etc.
So they might try looking at the idea that the heat source is localised there and spreads, as can be seen in the NASA sea area anomaly maps perfectly clearly, about twenty five years after they were told to . Those who tried to investigate got a quick kick out the door when it came to funding given the power of the AGW lobby.
If I recall correctly therer are a plethora of volcanic hot water vents in that area (below) which was maintained heated up the water temps therel BTW Steig and Nature should be shut down. They are a disgrace to Science (well, at least all the climate editors need to be fired from Nature)
And there was me thinking the Antarctic Ice Sheet was actually a lot larger than average.
Sea ice sheet, sorry.
Looking at Bob Tisdale’s chart for Southern Ocean SST: http://bobtisdale.files.wordpress.com/2013/06/14-southern.png – it seems to have gone through a significant downwards step change in 2006-2008, and despite a short-lived blip up this January, it’s still below the levels of both the 80s and the 90s.
It is virtually impossible to measure snowfall in Antarctica for several reasons. Firstly a blizzard is not falling snow it is blown snow. I have observed gales on the polar plateau where the blown snow was over 1000 m high with no cloud and blue sky above. The snow gauge in the Wright Valley measured 5mm water equivalent for the 12 months from Dec 1884 to Dec 1985 but was this snow blown off the Plateau or actual fallen snow ?
After the sea ice in McMurdo Sound broke out we had a lot of low cloud coming up the dry valleys every day, where the cloud touched the mountains it left snow behind. Only once in 4 months did we get any falling snow at Vanda Station (30 km inland) and that had totally ablated within a couple of hours of the snowfall stopping. The humidity in the valley before the sea ice broke out was about 7% after the break out it rose to 50 to 80 % during the day if I recall correctly.
Conclusion – most snow that accumulates in Antarctica is by accretion from water vapour in the air, not by snowfall.
The temperature of the water under the sea ice was -1.96°C which is the freezing point of sea water down there. As the water is in contact with huge amounts of ice that is not surprising. New winter ice freezes best if there are no storms while it is forming, then it remains clear and can radiate heat from the water beneath to space. If it gets covered with snow (snow does occur in coastal regions) or broken up by wave action, then it reflects a lot of heat back to the ocean rather than radiate it to space so the ice formed is not at thick as that formed without snow or wave action. Hope that info is useful to somebody.
Kev-in-Uk says:
June 14, 2013 at 12:19 am
Larry Kirk says:
June 13, 2013 at 9:20 pm
——————————-
points well appreciated.
The culinary arts of John of Ockham has made a sham of climatology.
I’m a bit of an Antarctic watcher, living in Australia we feel its extensive influence right up into the sub tropics and sometimes further. For anyone interested the University of Wisconsin has a great satellite composite of the complexities of the weather systems that traverse the Southern Ocean, and Meteoexploration.com (map room) offer current, temp, humidity, cloud, wind and pressure data.
I’d just like to make a couple of points: firstly anyone who believes that rising air temps are melting the Continental ice clearly doesn’t check the 2m temperatures very often because the vast majority of the area never even gets close to zero let alone above zero. And secondly, the ‘bit that sticks out towards South America’ i.e. the only bit where there is any melting is clearly exposed to ocean currents.
But what I find really awesome is the vast reservoir of ice and the ‘robust’ ice formation that takes place there each winter, it would appear that there’s more than enough ‘cold’ down there to ‘catastrophically’ chill the entire planet several times over.
As we speak there is a big chunk of Antarctica where the 2m temperature is minus 55 C…and the temperature at 10,000m is minus 60 C, now that’s what I CALL and adiabatic lapse rate!
Time to throw another log on the fire.