Monday, September 16, 2013

Achilles' heel of ice shelves is beneath the water, scientists reveal - Phys.Org

16 hours ago

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

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 climate system 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 ice shelves, 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: Warm ocean drives most Antarctic ice shelf loss, research shows

More information: Nature, DOI: 10.1038/nature12567

Journal reference: Nature

Provided by University of Bristol

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User comments : 7

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ubavontuba

2.6 / 5 (5) 15 hours ago

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 / 5 (4) 10 hours ago

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.

Franklins

-1 / 5 (4) 9 hours ago

Comment's rank below your filter threshold ... show
ubavontuba

2.3 / 5 (3) 8 hours ago

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

1 / 5 (3) 7 hours ago

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.

ubavontuba

-1 / 5 (2) 6 hours ago

Comment's rank below your filter threshold ... show
Water_Prophet

1 / 5 (2) 6 hours ago

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.

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

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

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 climate system 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 ice shelves, 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: Warm ocean drives most Antarctic ice shelf loss, research shows

More information: Nature, DOI: 10.1038/nature12567

Journal reference: Nature

Provided by University of Bristol

Thermal intake of melting ice as compared to thermal capacity of earth
created5 hours agoThough this topic mentions climate change, I don't think it really is about it that, strongly anyway. I've just joined...
How much water is in the atmosphere?
createdSep 11, 2013At any given moment do scientists have an idea of how much water is in the atmosphere? Can we compare it to how much...
Younger Dryas - likely the result of meteor impact
createdSep 10, 2013Origin and provenance of spherules and magnetic grains at the Younger Dryas boundary Yingzhe Wu, Mukul Sharma,...
the devil(bermuda)triangle
createdSep 06, 2013the northern part of the Atlantic ocean near Bermuda is prone for more tropical cyclones . many ships and jets are...
Younger Dryas - again
createdSep 03, 2013Pre-publish article: ...
What caused the mechanism of Plate Tectonics to begin?
createdSep 03, 2013Billions of years ago, something must have triggered rifts and the seperation of the first landmasses into the first...

More from Physics Forums - Earth

Related Stories

Warm ocean drives most Antarctic ice shelf loss, research shows

Jun 13, 2013

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.

Sediment wedges not stabilizing West Antarctic Ice Sheet

Sep 03, 2013

The stability of the West Antarctic Ice Sheet is uncertain as climate changes. An ice sheet such as the West Antarctic Ice Sheet that is grounded well below sea level on a bed that slopes toward the interior of the sheet ...

Mathematician uses skills to study Greenland's retreating glaciers (w/ Video)

Sep 11, 2013

Many outlet glaciers in Greenland feed ice from the land into fjords, where discharge of icebergs and melting of the glaciers by warmer ocean waters contribute to rising sea levels.

The contribution of the Greenland ice sheet to sea-level rise will continue to increase

Jul 10, 2013

New research has shown surface ice melt will be the dominant process controlling ice-loss from Greenland. As outlet glaciers retreat inland the other process, iceberg production, remains important but will not grow as rapidly.

Sea level rise: New iceberg theory points to areas at risk of rapid disintegration

Jul 22, 2013

In events that could exacerbate sea level rise over the coming decades, stretches of ice on the coasts of Antarctica and Greenland are at risk of rapidly cracking apart and falling into the ocean, according to new iceberg ...

Melting water's lubricating effect on glaciers has only 'minor' role in future sea-level rise

Aug 12, 2013

Scientists had feared that melt-water which trickles down through the ice could dramatically speed up the movement of glaciers as it acts as a lubricant between the ice and the ground it moves over.

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16 hours ago

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22 hours ago

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Sep 13, 2013

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Sep 13, 2013

Southwesterly wind shear has taken its toll on hurricane Humberto, and NASA's TRMM satellite noticed that in rainfall data.

NASA sees system 93L become Tropical Storm Ingrid, now soaking eastern Mexico

Sep 13, 2013

NASA and NOAA satellites have been tracking the progression of low pressure System 93L through the Caribbean Sea and into the southwestern Gulf of Mexico over a week's time, and it became Tropical Storm Ingrid ...

NASA sees Tropical Depression Gabrielle approaching eastern Canada

Sep 13, 2013

Eastern Canada is now expecting some winds and rain from Tropical Depression Gabrielle as it transfers its energy to a cold front. NASA's Aqua satellite captured an infrared image of Gabrielle that showed ...

User comments : 7

Adjust slider to filter visible comments by rank

Display comments: newest first

ubavontuba

2.6 / 5 (5) 15 hours ago

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 / 5 (4) 10 hours ago

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.

Franklins

-1 / 5 (4) 9 hours ago

Comment's rank below your filter threshold ...

show
ubavontuba

2.3 / 5 (3) 8 hours ago

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

1 / 5 (3) 7 hours ago

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.

ubavontuba

-1 / 5 (2) 6 hours ago

Comment's rank below your filter threshold ...

show
Water_Prophet

1 / 5 (2) 6 hours ago

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.

More news stories

Study shows projected climate change in West Africa not likely to worsen malaria situation

As public-health officials continue to fight malaria in sub-Saharan Africa, researchers are trying to predict how climate change will impact the disease, which infected an estimated 219 million people in ...

Scientists discover cosmic factory for making building blocks of life

Scientists have discovered a 'cosmic factory' for producing the building blocks of life, amino acids, in research published today in the journal Nature Geoscience.

Report: Climate change to shift Kenya's breadbaskets

Kenyan farmers and agriculture officials need to prepare for a possible geographic shift in maize production as climate change threatens to make some areas of the country much less productive for cultivation while simultaneously ...

Tropical forest carbon absorption may hinge on an odd couple

A unique housing arrangement between a specific group of tree species and a carbo-loading bacteria may determine how well tropical forests can absorb carbon dioxide from the atmosphere, according to a Princeton ...

NASA sends drones to track hurricanes' secrets

A pair of converted military drones are the US space agency's newest tools for tracking hurricanes and tropical storms, with the aim of improving forecasters' ability to predict them.

Africa's 'right-on' whale capital

Perched away from the world on the rocky southern tip of Africa, the town of Hermanus rose to global whale-watching renown almost by chance.

Japan nuclear-free as last reactor switched off

Japan went nuclear-free on Monday as it switched off its last operating reactor for an inspection, with no date scheduled for a restart amid strong public hostility to atomic power.

Superconductivity to meet humanity's greatest challenges

The stage is now set for superconductivity to branch out and meet some of the biggest challenges facing humanity today.

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Phobias—whether it's fear of spiders, clowns, or small spaces—are common and can be difficult to treat. New research suggests that watching someone else safely interact with the supposedly harmful object can help to extinguish ...

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Prescribing of strong opioid medications for non-cancer pain in the United States has nearly doubled over the past decade, reports a study in the October issue of Medical Care.

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