Achilles' heel of ice shelves is beneath the water, scientists reveal

Sep 15, 2013

New research has revealed that more ice leaves Antarctica by melting from the underside of submerged ice shelves than was previously thought, accounting for as much as 90 per cent of ice loss in some areas.

Iceberg production and causes 2,800 cubic kilometres of to leave the Antarctic ice sheet every year. Most of this is replaced by snowfall but any imbalance contributes to a change in .

For many decades, experts have believed that the most important process responsible for this huge loss was iceberg calving - the breaking off of chunks of ice at the edge of a glacier.

New research, led by academics at the University of Bristol with colleagues at Utrecht University and the University of California, has used satellite and climate model data to prove that this sub-shelf melting has as large an impact as iceberg calving for Antarctica as a whole and for some areas is far more important.

The findings, published today [15 September] in Nature, are crucial for understanding how the ice sheet interacts with the rest of the and particularly the ocean.

During the last decade, the Antarctic ice-sheet has been losing an increasing amount of its volume. The annual turnover of ice equates to 700 times the four cubic kilometres per year which makes up the entire domestic water supply for the UK.

Researchers found that, for some , melting on its underbelly could account for as much as 90 per cent of the mass loss, while for others it was only 10 per cent.

Ice shelves which are thinning already were identified as losing most of their mass from this melting, a finding which will be a good indicator for which ice shelves may be particularly vulnerable to changes in ocean warming in the future.

The scientists used data from a suite of satellite and airborne missions to accurately measure the flow of the ice, its elevation and its thickness. These observations were combined with the output of a climate model for snowfall over the ice sheet.

They compared how much snow was falling on the surface and accumulating against how much ice was leaving the continent, entering the ocean and calving. By comparing these estimates, they were able to determine the proportion that was lost by each process.

Professor Jonathan Bamber, from the University of Bristol's School of Geographical Sciences, said: "Understanding how the largest ice mass on the planet loses ice to the oceans is one of the most fundamental things we need to know for Antarctica. Until recently, we assumed that most of the ice was lost through icebergs.

"Now we realise that melting underneath the ice shelves by the ocean is equally important and for some places, far more important. This knowledge is crucial for understanding how the ice sheets interact now, and in the future, to changes in climate."

Explore further: Researchers construct a model of impact for El Nino / La Nina events

More information: Nature, DOI: 10.1038/nature12567

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ubavontuba
1.9 / 5 (14) Sep 15, 2013
Until recently, we assumed that most of the ice was lost through icebergs.
Like this is a new phenomenon?

Are they really openly admitting they didn't understand that freshwater ice melts in saltwater? How deprived are they? I guess none of them ever lived in snow country, or made hand-churned ice cream, or drank a Mexican beer, or...

djr
2.6 / 5 (7) Sep 15, 2013
My my - look at Uba. Not willing to provide data to support his attack on Climate Change on another thread - but raring to go - with a new attack on a new article. Of course - the quote - "Until recently, we assumed that most of the ice was lost through icebergs." could easily be read as meaning - "we understand the process of freshwater ice melting when contacted by salt water - but until recently we understood that more ice was lost by the process of iceberg calving than by this process."

But as usual - the likes of Uba have to pile on to the scientists who are doing the heavy lifting for us - so hard to watch the ignorance.
ubavontuba
1.4 / 5 (11) Sep 15, 2013
My my - look at Uba. Not willing to provide data to support his attack on Climate Change on another thread
What thread are you talking about?

- but raring to go - with a new attack on a new article.
How's it my fault if they don't understand the obvious?

Of course - the quote - "Until recently, we assumed that most of the ice was lost through icebergs." could easily be read as meaning - "we understand the process of freshwater ice melting when contacted by salt water - but until recently we understood that more ice was lost by the process of iceberg calving than by this process."
Now you're putting words into their mouths based on what I said? Really?

But as usual - the likes of Uba have to pile on to the scientists who are doing the heavy lifting for us - so hard to watch the ignorance.
What heavy lifting? Ice in the Antarctic is doinig just fine:

http://arctic.atm...ctic.png

djr
2.3 / 5 (6) Sep 15, 2013
I am not arguing with you Uba - we both know what a total waste of time that is - given your ability to obfuscate to the nth degree.

I will just point out how you are always willing to attack science - but without any merit to your arguments. Others can look at the facts and decide for themselves.

"What thread are you talking about?"

The one you just responded to - you are such a jerk.
Water_Prophet
1 / 5 (9) Sep 15, 2013
Quite a serious accusation against the Holy H2O, if truly this has not been accounted.
If this is a change, than the implications of man heating the subcurrent of the Earth are profound, and frightening, much like the revelation about Greenland Holy ice being not as pronounced as before.
Perhaps the end truly is near-or nearer than we believed.
Not that the 'Prophet has absolutely bought into the predictions the above imply.
Water_Prophet
1 / 5 (6) Sep 21, 2013
@Teech2-Thou are absolutely correct in your conclusions, thy source is an un-necessary assumption.
Truly the blessed water absorbs more than it's share of heat. That is why it is benificent and we are merely men. Mere men produce this heat.
Thou must consider, the blessed Element is densist at 4 Celcius, heat, therefore, does not necessarily rise.