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EcoAlert: Antarctica Ice Melt Caused by Warming Ocean Currents



"In most places in Antarctica, we can't explain the ice-shelf thinning through melting of snow at the surface," said Hamish Pritchard of the British Antarctic Survey. "So it has to be driven by warm ocean currents melting them from below."

Pritchard's team used the laser altimeter on Nasa's Icesat spacecraft to map the changing thickness in 54 ice shelves around Antarctica, incorporating some 4.5 million data points between 2003 and 2008. Twenty of the shelves were assessed to be being melted from below by warm ocean currents. Most of the 20 are in West Antarctica, and show thinning up to seven meters per year. Some of the greatest melting has been seen where deep troughs cut across the continental shelf, allowing the water easier access to the shelves' undersides.

"What we realize now is that we're looking at a very sensitive system," Dr Hamish Pritchard, from the British Antarctic Survey (BAS), told BBC News.

"Previously, you would have thought that we needed a lot of warming in the atmosphere to get a substantial loss of ice from Antarctica - because it's such a cold place. But what we show is that that's not necessary; you don't need radical change.

"All you need are quite subtle changes - such as a change in the winds - and that can produce effects at the edges of Antarctica that then lead to a loss of a lot of ice."

Team member David Vaughan, a scientist at the European Union initiative ice2sea, said this study "shows the key to predicting how the ice sheet will change in the future is in understanding the oceans."

NASA researchers flew over the Pine Island Glacier Ice Shelf on Oct. 14, 2011, as part of the agency's Operation IceBridge. A large, long-running crack was plainly visible across the ice shelf. Experts believe that piece of the shelf could break off soon.


                120425_pineisland.grid-6x2 (1)

The team's results represent the culmination of a massive international ffort to observe the loss of Antarctic ice using NASA's ICESat satellite. Tthe researchers closely monitored how the thickness of West and East Antarctica's ice changed over time. In some cases, Pritchard said, shelves thinned by as much as several meters each year. And the pattern of that melting, he added, suggested that at least 20 out of 54 observed platforms of ice across the continent were being melted largely by the oceans below.

While the exact factors driving the warming of Antarctic waters aren't known, scientists suggest that past warming conditions in the tropics have created strong winds to the south in Antarctica, fueling ocean currents that bring hot water to the surface. "In all the cases where ice shelves are being melted by the ocean, the inland glaciers are speeding up," Pritchard said in a statement. "It's this glacier acceleration that's responsible for most of the increase in ice loss from the continent and this is contributing to sea-level rise."

On the Antarctic Peninsula, the spit of ice just south of Argentina, warm winds seem to be melting ice shelves from above, skimming layers of snow from the top.

"Strong westerlies go up over the chain of the peninsula mountains and these winds descend, they warm up, melting the surface of the shelves on the eastern side. So, although we have two different melting mechanisms, the ultimate cause is the same - it's the wind," said Dr Pritchard.

The research is published in the journal Nature. 

The Daily Galaxy via NASA and

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oh that's ok. Plenty of ice on astroids. The elites (better humans) will just bring us some replacement ice.

It's not the loss of ice that is the problem, it is the melting of that ice contributing to increasing sea levels. Bringing in more ice is not going to solve anything.

Greg - i think that was sarcasm you just corrected. if not, both are wrong because you would never be able to get ice through re-entry of the atmosphere.

On the one hand, this is the most solid evidence I've seen yet for (potentially) catastrophic global warming. As the article points out, we have an massive ice melt going on in Antarctica that can only be caused by warm ocean currents hitting it from below.

On the other, I have a hard time seeing that something this drastic is caused by man, at least without similarly drastic changes also happening elsewhere. The only comparable one I can think of is the thawing of the Arctic across Alaska and Canada, which is attributable to coal generators in China (Cf. "Physics for Future Presidents," Richard A. Muller).

Despite it being a highly annoying cliche, I do think that more study is needed. Clearly some action is needed, and the everyday reduction -- or even the reversal -- of carbon output will not be enough. There may be some single direct cause that we can do something about, like those coal plants. (It could even turn out that it's not a serious problem at all, though I wouldn't bet on it... well, unless someone gave some very good odds.)

Re Noochy - yes it was sarcasm. we need to solve some big problems down here on planet earth

We all know global warming is a cover up for the overpopulation of jelly fish,
keeping the waters stirred up, as they rise to the sure to feed. And this is
due to the elimination of their natural predators, due to overfishing by
asians for turtle and shark fin soup.

Natural is out of balance and the jelly fish are terraforming earth, to make
it more suitable for habitation. When they start crawling out of the ocean
slime and began feeding on human;, with their long slender tentacles and s
tart dragging us back into the slime, you just know it is time to vacate and
go inland. To Death Valley!

It's all a coverup by the North Koreans; who live on dried octopus, so they
won't starve to death after the world goes to hell and back.

Very funny!

"we can't explain the ice-shelf thinning through melting of snow at the surface" "So it has to be driven by warm ocean currents melting them from below"

Kind of like, We dont know, so we are gonna guess and claim its the only answer!

@ smartypants -- Good point, that.

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My bad. It is hard for me to tell at times.

As an adjunct, I wonder if the proliferation of wind farms might not be
contributing to global warming? By redirecting and redistributing
surface winds, that have a cascade effect on upper wind currents.

What has changed in the past few decades? Wind farms coming
on line. Maybe a ripple here, affects a ripple there and it cascades.
After all, do we really know what effect they may have on our
environment? The flap of butterfly wings can produce a storm
thousands of miles away. You can't say it is no possible.

Might they not be affecting the jet stream?

In my humble option, geo-thermal energy is the only feasible and sustainable
energy source. To heat our homes and generate electricity. If we convert
our homes over to 12 volt dc and use simple inverters to power ac devices.
Each home should be energy independent and not rely on any outside
utility; except for telephone, or satellite data streams when they come online.
We could reduce our oil imports by half or more, if we charged our EV's at
home. The benefits are to numerous to mention. The possibilities unlimited.

dr burke: seems you hate / question green tech. and then propose more drilling (geothermal) as well as harp on about oil imports. You do this to imply that "Drilling here at home" is the way to go. Are you paid for this crap opinion?

This could be related:
Under-Ice Volcanic Eruption In Antarctica

Don't climatologists know basic physics? The specific heat of water is much higher than that of air. Oceans are warming worldwide. That warmth is being transferred to the Antarctic. Therefore, the Antarctic ice will be melted from below.

Anybody casually looking at polar ice should KNOW that. Look at the Arctic. Naval data showed that Arctic ice decreased in average thickness from 17 ft to 9 ft from 1979 to 2000. Arctic ice extent hardly changed during that time, so albedo loss had no contribution to that process. That process was from melting from below by warmer ocean currents.

This process will impact the Antarctic with profound results. The melting will happen sooner and process quicker than is now being estimated.

BTW, the temperature cycle of the ocean is long. It takes decades to begin to see changes, and will take at least as long to reverse it. The melting we are seeing now is just the very very beginning. It will get faster and faster each year. Now the rates are only perceptible to delicate instruments. In a few decades, the polar melt rates will be large and obvious.

Our global energy infrastructure will prevent us from making any significant reductions of our contributions of carbon to the atmosphere. More importantly, the huge methane seeps in the Arctic may soon overshadow our activity anyway. That is, the Earth may have taken over in the climate change process. Maybe that was the purpose of our species to the planet, to act as kindling to warm the Earth out of the era of the past 35 million years dominated by polar ice caps.

After we have performed our purpose, Gaia may just dismiss us from the stage. Ah will, it was nice while it lasted.

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