BBC: Esa's Cryosat mission sees Antarctic ice losses double


mentalfloss
#1
Esa's Cryosat mission sees Antarctic ice losses double

Antarctica is now losing about 160 billion tonnes of ice a year to the ocean - twice as much as when the continent was last surveyed.

The new assessment comes from Europe's Cryosat spacecraft, which has a radar instrument specifically designed to measure the shape of the ice sheet.

The melt loss from the White Continent is sufficient to push up global sea levels by around 0.43mm per year.

Scientists report the data in the journal Geophysical Research Letters.

The new study incorporates three years of measurements from 2010 to 2013, and updates a synthesis of observations made by other satellites over the period 2005 to 2010.

Cryosat has been using its altimeter to trace changes in the height of the ice sheet - as it gains mass through snowfall, and loses mass through melting.

'Big deal'

The study authors divide the continent into three sectors - the West Antarctic, the East Antarctic, and the Antarctic Peninsula, which is the long finger of land reaching up to South America.

Overall, Cryosat finds all three regions to be losing ice, with the average elevation of the full ice sheet falling annually by almost 2cm.


Cryosat's double antenna configuration allows it to map slopes very effectively
In the three sectors, this equates to losses of 134 billion tonnes, 3 billion tonnes, and 23 billion tonnes of ice per year, respectively.

The East had been gaining ice in the previous study period, boosted by some exceptional snowfall, but it is now seen as broadly static in the new survey.

As expected, it is the western ice sheet that dominates the reductions.

Scientists have long considered it to be the most vulnerable to melting.

It has an area, called the Amundsen Sea Embayment, where six huge glaciers are currently undergoing a rapid retreat - all of them being eroded by the influx of warm ocean waters that scientists say are being drawn towards the continent by stronger winds whipped up by a changing climate.

About 90% of the mass loss from the West Antarctic Ice Sheet is going from just these few ice streams.

At one of them - Smith Glacier - Crysosat sees the surface lowering by 9m per year.


Some western ice streams such as Pine Island Glacier are retreating and thinning rapidly
"CryoSat has given us a new understanding of how Antarctica has changed over the last three years and allowed us to survey almost the entire continent," explained lead author Dr Malcolm McMillan from the NERC Centre for Polar Observation and Modelling at Leeds University, UK.

"We find that ice losses continue to be most pronounced in West Antarctica, along the fast-flowing ice streams that drain into the Amundsen Sea. In East Antarctica, the ice sheet remained roughly in balance, with no net loss or gain over the three-year period," he told BBC News.

Cryosat was launched by the European Space Agency in 2010 on a dedicated quest to measure changes at the poles, and was given a novel radar system for the purpose.

It has two antennas slightly offset from each other. This enables the instrument to detect not just the height of the ice sheet but the shape of its slopes and ridges.

This makes Cryosat much more sensitive to details at the steep edges of the ice sheet - the locations where thinning is most pronounced.

It also allows the satellite to better detect what is going on in the peninsula region of the continent where the climate has warmed rapidly over the past 50 years.

"The peninsula is extremely rugged and previous satellite altimeters have always struggled to see its narrow glaciers. With Cryosat, we get remarkable coverage - better than anything that's been achieved before," said Prof Andy Shepherd, also of Leeds University.

Future change

The GRL paper follows hard on the heels of two studies that have made a specific assessment of the future prospects for the Amundsen Sea Embayment.

One of these reports concluded that the area's glaciers were now in an irreversible retreat.

The other paper, considering one of the glaciers in detail, suggested the reversal process could take several hundred years to be completed.

A loss of all the ice in the six glaciers would add about 1.2m to global sea level.

This is still a small fraction of the total sea-level potential of Antarctica, which holds something like 26.5 million cubic km ice (or 58m of sea-level rise equivalent). But the continent has been largely insulated from some of the warming influences taking place elsewhere in the world and it is important, say scientists, to keep a check on any changes that are occurring, and the speed with which they are happening.

Prof Duncan Wingham proposed the Cryosat mission and is its principal investigator. He told BBC News: "We lack the capability to predict accurately how the Amundsen ice streams will behave in future.

"Equally, a continuation or acceleration of their behaviour has serious implications for sea level rise. This makes essential their continued observation, by Cryosat and its successors."

Prof David Vaughan of the British Antarctic Survey, who was not involved in the Cryosat survey, commented: "The increasing contribution of Antarctica to sea-level rise is a global issue, and we need to use every technique available to understand where and how much ice is being lost.

"Through some very clever technical improvements, McMillan and his colleagues have produced the best maps of Antarctic ice loss we have ever had. Prediction of the rate of future global sea-level rise must begin with a thorough understanding of current changes in the ice sheets - this study puts us exactly where we need to be."

BBC News - Esa's Cryosat mission sees Antarctic ice losses double
 
captain morgan
+1
#2  Top Rated Post
Loc posted this earlier... Read it and learn

Antarctica’s ice losses on the rise – with a sanity check


From Geophysical Research Letters and the University of Leeds:


Three years of observations show that the Antarctic ice sheet is now losing 159 billion tonnes of ice each year — twice as much as when it was last surveyed. See below for some sanity check calculations on why 159 billion tonnes really isn’t much more than a flyspeck in the scheme of things.

Antarctica’s ice losses on the rise


From Climatesanity: Conversion factors for ice and water mass and volume


If one cubic kilometer of water (i.e., one gigatonne of water) is spread evenly over the entire 361 million square kilomters, the thickness of the new layer of water will be given by:

1 km³ / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns.

Or, in terms of gigatonnes:

1 Gt x (1 km³/Gt) / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns / Gt

That is, one cubic kilometer of water (i.e., one gigatonne of water) will add less than 3 millionths of a meter to the oceans!


here:


Antarctica’s ice losses on the rise – with a sanity check | Watts Up With That?
 
petros
#3
Sea ice or continental? If continental how are warm waters melting continental ice? Magic water that flows up hill and since when did it start snowing on the polar desert to dramatically stop because of global warming. Global warming will make the opposite happen. It would precipitate rather than stay a desert.
 
mentalfloss
#4
Quote: Originally Posted by captain morgan View Post

Loc posted this earlier... Read it and learn

Antarctica’s ice losses on the rise – with a sanity check


From Geophysical Research Letters and the University of Leeds:


Three years of observations show that the Antarctic ice sheet is now losing 159 billion tonnes of ice each year — twice as much as when it was last surveyed. See below for some sanity check calculations on why 159 billion tonnes really isn’t much more than a flyspeck in the scheme of things.

Antarctica’s ice losses on the rise


From Climatesanity: Conversion factors for ice and water mass and volume


If one cubic kilometer of water (i.e., one gigatonne of water) is spread evenly over the entire 361 million square kilomters, the thickness of the new layer of water will be given by:

1 km³ / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns.

Or, in terms of gigatonnes:

1 Gt x (1 km³/Gt) / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns / Gt

That is, one cubic kilometer of water (i.e., one gigatonne of water) will add less than 3 millionths of a meter to the oceans!


here:


Antarctica’s ice losses on the rise – with a sanity check | Watts Up With That?

I feel dirty for actually clicking the link for this douche, but the comments on his own damn site show his calculation is wrong.

The whole internets knows Watts has no credibility except for you guys lol
 
petros
#5
How can you get dirtier than being sh-t on and enjoying it?
 
mentalfloss
-1
#6
I'm sorry you're too chicken sh-t to reveal who you are investing in.
 
Praxius
#7
All of this is just more "blah blah blah" and "Whu wah wah wah wu" like Charlie Brown's teacher.

And another report released last week said we're all Fk'd now anyways because the big chunks that fell off recently can't be fixed and it's too late to do anything to turn things around.

Even if Al Gore's fanatical crap took hold of the world and people started making changes this still would have happened because any real "Change" needed to be done a lot earlier when people were freaking out in the mid/late 80's.

If it's all hype and fear mongering then we have nothing to worry about.

If Global Warming is true, then it's too late to do anything now and we're all screwed anyways, so there's no point worrying about that either.

Either way, if dramatic changes are taking place, good.... The Earth needs a new look and I was getting bored of the old one. Humanity needs a challenge.
 
petros
#8
Quote: Originally Posted by mentalfloss View Post

I'm sorry you're too chicken sh-t to reveal who you are investing in.

It's a secret? Why would it matter? Why don't you have investments? Who do you work for? I'll invest in them and you can be one of my peons.
 
mentalfloss
#9
Quote: Originally Posted by petros View Post

It's a secret?

Yes?
 
taxslave
#10
Not being real good at math but being somewhat logical I have to question the numbers. Since the bulk of an iceberg is already submerged and the weight of the rest is also displacing water should it not follow that melting glaciers will have zero or close to influence on seal level? From the calculations I have seen no one seems to be taking this into account while anyone that knows about boats does automatically.
 
petros
#11
Quote: Originally Posted by mentalfloss View Post

Yes?

No....
 
Zipperfish
#12
Quote: Originally Posted by taxslave View Post

Not being real good at math but being somewhat logical I have to question the numbers. Since the bulk of an iceberg is already submerged and the weight of the rest is also displacing water should it not follow that melting glaciers will have zero or close to influence on seal level? From the calculations I have seen no one seems to be taking this into account while anyone that knows about boats does automatically.

Yes, we must have completely overlooked that! What a revelation. Thank you, taxslave. This changes everything.
 
petros
#13
If he is unsure explain to him why he is either right or wrong.
 
mentalfloss
#14
Quote: Originally Posted by petros View Post

No....

Then show your partisanship card.
 
petros
#15
Quote: Originally Posted by mentalfloss View Post

Then show your partisanship card.

What card? I'm not a party loser. Are you?
 
coldstream
#16
Funny how reports of the return of the ice packs to the Arctic has disappeared from the mainstream media... after it was touted that they were gone forever. I wonder what they'll come up with when the normal cycles bring back the ice back at the South Pole. I know they'll come up with something.
 
mentalfloss
#17
Quote: Originally Posted by petros View Post

What card? I'm not a party loser. Are you?

Then who do you work for?
 
petros
#18
Quote: Originally Posted by mentalfloss View Post

Then who do you work for?

Me..
 
mentalfloss
#19
Quote: Originally Posted by petros View Post

Me..

Living in a retirement home doesn't count.
 
Zipperfish
#20
Quote: Originally Posted by coldstream View Post

Funny how reports of the return of the ice packs to the Arctic has disappeared from the mainstream media... after it was touted that they were gone forever. I wonder what they'll come up with when the normal cycles bring back the ice back at the South Pole. I know they'll come up with something.

Actually on the decadal scale (since satellite measurements began in 1979) artic sea ice has significantly decreased while antarctic ice has (not-so-significantly) increased. You can see the charts on National Sea and Ice Data Center.

Your confusion is understandable though because in the last year Arctic sea ice recovered substantially in comparison to the season before (although still not matching levels back to 1979) whereas a recent study found that important glaciers on the Western Antarctic ice sheet are breaking up (although the Antarctic as a whole continues to gain ice).

The media will focus on whatever is happening that day. The media generally have a memory of around 4 months.

Quote: Originally Posted by petros View Post

If he is unsure explain to him why he is either right or wrong.

Floating sea ice will have a minimal impact on sea level since it is already displacing volume in the water (there is minimal sea level rises due to the density difference between salt water and freshwater (of which sea ice is composed). Ice on land that slips into the sea, on the other hand adds it's full volume to total sea level (minus the slight rise in elevation of land that was being pushed down by the ice).
 
petros
#21
Quote: Originally Posted by mentalfloss View Post

Living in a retirement home doesn't count.

I'm only semiretired at 46. I hope you get to be so lucky. Work hard son.
 
MHz
#22
Quote: Originally Posted by taxslave View Post

Not being real good at math but being somewhat logical I have to question the numbers. Since the bulk of an iceberg is already submerged and the weight of the rest is also displacing water should it not follow that melting glaciers will have zero or close to influence on seal level? From the calculations I have seen no one seems to be taking this into account while anyone that knows about boats does automatically.

I think the theory is that the ice forms on land and then hits the oceans. If you put a punch of icecubes in a tub with water in it the level will be higher when the ice goes in. That being said the Oceanic crust has about 60,000 km (http://www.geo.umass.edu/faculty/wil...%20Chapter.pdf) of spreading rifts that is several miles deep in a lot of locations. If that spreading is measured at a rate of and 2cm/year how much water is that that would be needed and no rise in oceanic levels would happen, if the same amount of land is not subducted at the same depth the levels in the ocean should be dropping and to rise the amount of ice would first have to fill up that new area. That could be 3,600,000 cubic km of new space in the oceans that would need that much water to stop from dropping. The Atlantic would seem to show that spreading is greater than 'subduction'.

Quote: Originally Posted by mentalfloss View Post

Living in a retirement home doesn't count.

That isn't called living, it is called waiting to die.
 
Cliffy
#23
Unprecedented B.C. glacier melt seeps into U.S. climate change concerns

The mountains of British Columbia cradle glaciers that have scored the landscape over millennia, shaping the rugged West Coast since long before it was the West Coast.
But they're in rapid retreat, and an American state-of-the-union report on climate change has singled out the rapid melt in British Columbia and Alaska as a major climate change issue.

Unprecedented B.C. glacier melt seeps into U.S. climate change concerns - British Columbia - CBC News