Antarctic icecap is melting more slowly than previously estimated, scientists find

Nov 29, 2012
Antarctic icecap melt slower than thought

(Phys.org)—The Antarctic icecap is melting more slowly than previously estimated, according to new estimates based on satellite measurements and GPS sensors on the ground.

The authors of the study, published in Nature, estimate an annual total ice loss of 69 billion tonnes, plus or minus 18 billion – between half and a third of previous estimates, and equivalent to only around 0.19mm of sea-level rise a year.

Changes in vary across the continent. The area along the coast is losing ice at a fast and accelerating rate, whereas West Antarctica as a whole is roughly stable and is gaining substantial amounts of ice.

Antarctica is warming due to worldwide but it's still extremely cold; away from where the ice flows into the warming sea, it's very difficult for large volumes of ice to melt, so changes in ice mass in the continent's interior may have more to do with global patterns of precipitation – that is, how much it snows, replenishing ice stocks – than with the air temperature.

Recent ice- from has been largely counterbalanced by mass gain in the interior, so the continent's total contribution to sea level is less than previously believed. In the longer term, though, the scientists behind the study say that if temperatures keep rising, this balance cannot be depended on. Antarctica holds enough water to raise sea level by around 59 metres, so if it starts to melt more quickly there is the potential for a dramatic increase in the already worrying rate of sea-level rise.

'The concern is that sea levels are already rising about 3mm a year, but it now turns out that's without a large contribution from in Antarctica,' says Dr Rory Bingham of Newcastle University, one of the paper's authors. 'There are some areas with very heavy loss of ice mass, but at the moment the gain in ice mass in East Antarctica is largely compensating. Worryingly there are signs of acceleration in the regions of heavy mass loss. Should this continue sea-level rise could accelerate substantially.'

He says that the continent's western reaches already seem less stable than elsewhere, with fast changes to ice mass in places like the Pine Island Glacier where warmer seawater and air temperatures are promoting melting.

The findings will help scientists understand the history of the Antarctic ice since the last ice age, which has huge implications for how it will respond to climate change over the next few centuries, and hence how much it might contribute to global rise.

During the last ice age, there was far more ice covering Antarctica. It was so heavy that it deformed the Earth below, forcing the hot rocks of its mantle away from Antarctica and causing the surface of the land to sink. Ever since the end of the ice age removed much of that weight of ice, the land has been slowly rebounding as the mantle has flowed back into the region - a process called Glacial Isostatic Adjustment, or GIA.

This makes it hard to measure changes in how much ice there is using satellites. The GRACE satellites have sensitive instruments to read minute variations in the strength of the Earth's gravity field caused by differences in the amount of mass from place to place - areas where the planet's crust is thicker have more mass, for example. Their results show a clear trend of decreasing mass in the Antarctic. But this fall in mass is made up of a combination of two trends - on the one hand ice melting causes mass to fall, and on the other GIA adds to the continent's mass by adding rock underneath it. Scientists haven't been sure exactly how much GIA has been happening, meaning they couldn't accurately estimate the rate of ice melt.

The new paper addresses that problem, assessing the rate of GIA - and hence also of ice loss - far more accurately than has ever before been possible. The researchers drew on earlier work by members of the same team installing on the rare rocky outcrops poking through the Antarctic icecap. This let them measure the speed of the rock's rebound directly. For this paper, they created a new model of GIA into which to feed the results. They could then subtract the GIA estimates from the readings of the overall change in the mass of the Antarctic provided by GRACE to pinpoint the contribution of ice melting.

They concluded that the landmass has been gaining mass more slowly than earlier estimates suggested, meaning that in order to make the figures add up the loss of ice must also have been slower than had been assumed.

Bingham says the GRACE satellites probably won't be flying for much longer, and that it's vital replacements are launched soon so that researchers can continue to monitor changes in the land and ice mass of Antarctica over time.

Explore further: Melting ice cap opening shipping lanes and creating conflict among nations

More information: King, M. et al., Lower satellite-gravimetry estimates of Antarctic sea-level contribution, Nature 491, 586-589 (22 November 2012) doi:10.1038/nature11621.

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User comments : 26

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Shootist
2.3 / 5 (22) Nov 29, 2012
You can just hear the grief as the author wails that the Antarctic ice isn't cooperating with the Greens, Reds and other enviro-fascists.
FrankHerbert
2.8 / 5 (16) Nov 29, 2012
But I thought it was all a conspiracy anyway? Why would they report this if so?

PS: Moron
ScooterG
1.8 / 5 (21) Nov 29, 2012
You can just hear the grief as the author wails that the Antarctic ice isn't cooperating with the Greens, Reds and other enviro-fascists.


LOL

The only time physorg will publish a report on something that does not edify global warming is when that report can be used to edify global warming. Comprende??

Global warming is nothing, it's everything, it's magical - and it represents everything that's bad about capitalism.
CapitalismPrevails
2.4 / 5 (17) Nov 29, 2012
Somebody better save this article to their hard drive. It'll probably get censured!
djr
3.6 / 5 (14) Nov 29, 2012
The only time physorg will publish a report on something that does not edify global warming is when that report can be used to edify global warming. Comprende??

So you have made your point - you don't think that physorg is a trusted source of information. Now piss off - leave those of us that respect phyorg to learn - and you can go read some flat earth, or young earth creationist web sites. Why do you feel compelled to attack physorg all the time? Just piss off and let us enjoy our science.
runrig
4.1 / 5 (9) Nov 29, 2012
You can just hear the grief as the author wails that the Antarctic ice isn't cooperating with the Greens, Reds and other enviro-fascists.


Actually, quite the opposite in my case and to anyone who knows the science. If you read the article and/or understood the science - it meets the expectations GW science has .....
"Antarctica is warming due to worldwide climate change but it's still extremely cold; away from where the ice flows into the warming sea, it's very difficult for large volumes of ice to melt, so changes in ice mass in the continent's interior may have more to do with global patterns of precipitation – that is, how much it snows, replenishing ice stocks – than with the air temperature."
You lot continue to equate warming with melting. It's not that simple - when it is cold enough the rain eqivalent snowfall rises ( air at -10C carries more WV than air at -12C ). This fighting melting on the peripheries of such a massive frigid continent. Basic meteorology.
ScooterG
1.8 / 5 (19) Nov 29, 2012
Just piss off and let us enjoy our science.


If the same scientific protocols used to support AGW were applied in any other scientific discipline, they would be laughed off this website.

Junk science is abhored by the members of physorg...unless that junk science concerns climate change, in which case junk science is revered.
Jeddy_Mctedder
1.7 / 5 (12) Nov 29, 2012


point is-----models may be useful, but they are looking at a chaotic system. micro predictions about a macro chaotic system are absurd. it is one thing to say global warming is occuring , it is another thing entirely to claim models of this system can be so accurate as to tell us how much more devastating natural catastrophes will be in the next 100 years because of the additional climate forcing due to manmade c02 production expectation.

the lie is that the modelers' hyperspecific predictions of large systems on a short duration is called science. it's as much science as gambling on stocks day to day is mathematically solveable as a function of economic theory.
it aint. you can explain the stock markets macro behavior with finance and economics, not its day to day behavior.
tony10cents
1 / 5 (5) Nov 29, 2012
anyone ever filled a glass with ice and water to the rim and watch the ice melt why doesn't it spill over?
ubavontuba
1.4 / 5 (10) Nov 30, 2012
lengould100
3.3 / 5 (7) Nov 30, 2012
anyone ever filled a glass with ice and water to the rim and watch the ice melt why doesn't it spill over?

Wow, you denialist kiddies are getting dumber all the time LOL.

Interesting quote from the article.
Antarctica holds enough water to raise sea level by around 59 metres,
That's about 183 feet for you american deniers.

I strongly agree, we're getting dead sick and tired of the stupidity of you religious denialists predictability on this site. You're just hurting what you think is your cause.
Egleton
2.3 / 5 (8) Nov 30, 2012
"Global warming is nothing, it's everything, it's magical - and it represents everything that's bad about capitalism"

There is no Capitalism. The USA is a Fascist State. A Fascist State is where industry and the Government are indistinguishable. You have the best politicians that money can buy.
ScooterG
1.8 / 5 (15) Nov 30, 2012
"Global warming is nothing, it's everything, it's magical - and it represents everything that's bad about capitalism"

There is no Capitalism. The USA is a Fascist State. A Fascist State is where industry and the Government are indistinguishable. You have the best politicians that money can buy.


Some industry in the US is in bed with the government, but not all.

Big Climate Change is one industry that is.
FrankHerbert
3.8 / 5 (10) Nov 30, 2012
AGW deniers: Explain to me how this article fits into your conspiratorial worldview.
runrig
3.4 / 5 (5) Nov 30, 2012

Junk science is abhored by the members of physorg...unless that junk science concerns climate change, in which case junk science is revered.


Climate science is no more "junk" than any other science - it just happens to be the one you focus on and dislike being told your worldview is wrong. Correction .... dislike being told ( equates with socialism ) and take the contrarian view by default. Are you also the type that thinks weather forecasts are worthless because they are occasionally wrong? Well they would be wouldn't they - because they are forecasts. You just have to go with the probabilities, especially if it is of such import as AGW. A truly glass half-empty type I suspect.
ScooterG
1.6 / 5 (13) Nov 30, 2012
Climate science is no more "junk" than any other science - it just happens to be the one you focus on and dislike being told your worldview is wrong.


You are wrong...dead wrong.

No other science I know of is promoted by known hucksters who are followed and revered by obvious enviro-nazis; who as a matter of practice and principal utilize false and mis-leading data, all for the purpose of shaking-down consumers, disrupting economies, and disrupting people's lives.

The leopard don't change his spots, and history don't lie.
lengould100
3.6 / 5 (9) Nov 30, 2012
ScooterG every time I decide to take you guys on I provide you irrefutable references which prove your claims are incorrect, and all you guys can provide is references to some guys personal blog, or to "research" supported by the likes of Cato Institute or some coal company. Talk about real, as you put it, "-nazis; who as a matter of practice and principal utilize false and mis-leading data, all for the purpose of shaking-down consumers"

Give it up. PLEASE. And PLEASE get the heck off the genuine science sites.
runrig
3.4 / 5 (5) Dec 01, 2012
Climate science is no more "junk" than any other science - it just happens to be the one you focus on and dislike being told your worldview is wrong.


You are wrong...dead wrong.

No other science I know of is promoted by known hucksters who are followed and revered by obvious enviro-nazis; who as a matter of practice and principal utilize false and mis-leading data, all for the purpose of shaking-down consumers, disrupting economies, and disrupting people's lives.

The leopard don't change his spots, and history don't lie.

I'm sorry but that comment says more about you than ever does your comments about the objects of your anger/derision. There is a psychological name for it I believe. Suffice to say that that stance is not welcome here - this a science website - and those of us of that background find it offensive. Why waste our/your time. We plainly are not going to change your mind and neither you ours.
ubavontuba
1.7 / 5 (11) Dec 01, 2012
I'm sorry but that comment says more about you than ever does your comments about the objects of your anger/derision. There is a psychological name for it I believe. Suffice to say that that stance is not welcome here - this a science website - and those of us of that background find it offensive. Why waste our/your time. We plainly are not going to change your mind and neither you ours.
But he's right.

In any other field of science, scientists behaving as so many of the AGW proponents do, would be sidelined into obscurity (at best). Almost every study they perform is obviously biased with the ideal that whatever they find must be a result of AGW.

This has resulted in many conflicting studies. Some asserting Antarctica is melting rapidly, due to AGW. Others claiming the Antarctic icesheets are rapidly growing, as a result of AGW.

In the example above, it doesn't even matter which study is actually correct, as both are equally biased.

gregor1
1.4 / 5 (9) Dec 01, 2012
The trouble is you true believers don't quite get the scientific method. This requires that you make an hypothesis which you then try to disprove. If you only accept the evidence that supports your hypothesis then you are guilty of confirmation bias and are building a quasi-religion. It was evident from the beginning when the term skeptic was used as a term of derision that this was happening. Skepticism is science.You can't be an activist and a scientist because objectivity is a basic requirement. The fact that many of you resort to name calling and abuse indicates the your objectivity has long since gone out the window.
gregor1
1.5 / 5 (8) Dec 01, 2012
Scientists do science, activists do spin.It's the spin that we now see unravelling spectacularly in study after study. The above is just one of many. In the following quote from 1989 we see Stephen Schneider, professor of climate science from Stanford making his decision to turn to the dark side public.

"To do that we need to get some broadbased support, to capture the public's imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have. This 'double ethical bind' we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both." (Quoted in Discover, pp. 45–48, Oct. 1989)
gregor1
1.5 / 5 (8) Dec 02, 2012
Interesting that they don't mention the Icesat data which shows Antarctica gaining ice.
http://wattsupwit...-losses/
ScooterG
1.4 / 5 (9) Dec 02, 2012
I'm sorry but that comment says more about you than ever does your comments about the objects of your anger/derision. There is a psychological name for it I believe. Suffice to say that that stance is not welcome here - this a science website - and those of us of that background find it offensive. Why waste our/your time. We plainly are not going to change your mind and neither you ours.


Ha!

Re AGW: Fraud/extortion are what bother me most. Second to that would be the millions of wasted dollars the taxpayers are shelling out.
VendicarD
3 / 5 (4) Dec 03, 2012
Probably because Antony Watts is a washed up radio weather announcer who makes his living by denying the reality of CO2 enhanced climate change.

He wrote the nonsense article you are referencing.

Who are you going to use next as a scientific reference? A chronic liar like Mit Ronmey?

"Interesting that they don't mention the Icesat data which shows Antarctica gaining ice." - GregorTard
ubavontuba
1 / 5 (5) Dec 03, 2012
Probably because Antony Watts is a washed up radio weather announcer who makes his living by denying the reality of CO2 enhanced climate change.

He wrote the nonsense article you are referencing.

Who are you going to use next as a scientific reference? A chronic liar like Mit Ronmey?

"Interesting that they don't mention the Icesat data which shows Antarctica gaining ice." - Gregor1
Gregor1's data concerns NASA Icesat science. Are you suggesting you have a problem with NASA Icesat science?

gregor1
1 / 5 (4) Dec 03, 2012
He hates the science so he tries to shoot the messenger