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A deep crack on on Antarctica's Larsen C ice shelf has nearly severed off one of the largest icebergs ever recorded:
One of the largest icebergs ever recorded — 2,500 square miles, about the size of Delaware — is about to break off Antarctica, according to the European Space Agency. The iceberg could speed up the break-off of other ice chunks, eventually eating away at a barrier that prevents ice from flowing to the sea.
The impending iceberg is being carved from one of the continent's major ice shelves, called Larsen C. Scientists have been monitoring Larsen C for months now, as a deep crack has slowly extended over the course of 120 miles. Only about three miles of ice are keeping the iceberg attached to the shelf, ESA says. No one knows when it will break off — it could be any moment — but when it does, the iceberg will likely be 620 feet thick (about the height of the Waldorf Astoria hotel in New York) and contain roughly 1 trillion tons of ice. It'll be drifting north toward South America, and could even reach the Falkland Islands. "If so it could pose a hazard for ships in Drake Passage," Anna Hogg from the University of Leeds, said in a statement.
Also at BBC.
(Score: 4, Informative) by kaszz on Thursday July 06 2017, @10:32AM (23 children)
Volume of water added: 1 trillion tons of ice = 1e12 m³ (approximately)
Total surface [hypertextbook.com] area of Earth seas: 3.618e14 m²
Added sea height from this ice block: 1e12 / (361800000*1000^2) = 0.002764 meters = 2.8 mm
How it affects Gulf Stream etc is another matter.
(Score: 2, Informative) by Anonymous Coward on Thursday July 06 2017, @10:35AM (2 children)
This ice is already in the water though?
(Score: 2) by bob_super on Thursday July 06 2017, @06:16PM (1 child)
A good part of it was on land until fairly recently.
(Score: 0) by Anonymous Coward on Thursday July 06 2017, @09:19PM
I honestly don't know, but we seem to have a constant stream of articles about this so you would think we would know if these articles were worth anything.
(Score: 1) by shrewdsheep on Thursday July 06 2017, @10:40AM (3 children)
The biggest factor in rising sea levels (at this moment) is thermal expansion. Potentially, this ice could lower sea temperatures, causing thermal shrinkage. Doing the exact calculations is left as an exercise.
(Score: 2) by acid andy on Thursday July 06 2017, @11:00AM (2 children)
Surely the cooling effect of that block of ice would only be very temporary whereas the greenhouse effect (probably responsible for that ice melting to begin with) is much more prolonged so the net result over the longer term is still increased thermal expansion. Is that why you qualified your statement with "at this moment"?
Of course the warmer air that is melting the ice will warm up the surface of the sea slightly at the same time as well.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by TheRaven on Friday July 07 2017, @09:26AM (1 child)
sudo mod me up
(Score: 0) by Anonymous Coward on Friday July 07 2017, @10:30AM
This will decrease the albedo of the surface and increase it's heat capacity, but that isn't what the greenhouse effect refers to.
(Score: -1, Troll) by Anonymous Coward on Thursday July 06 2017, @10:55AM (2 children)
The volume of this over-hyped ice cube is already .62% displaced. Further, since the water it is dissolving into is nearly the same temperature as the ice, the thermal delta coefficient is infinitesimally small.
A few cloudy days over the vast sea region causes more than enough radiated surface cooling to render the net effects insignificant.
#hype #junkscience #clickbait
(Score: 2) by acid andy on Thursday July 06 2017, @11:02AM
That doesn't matter. The point is that over time, on average, they are both getting warmer.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 0) by Anonymous Coward on Thursday July 06 2017, @02:56PM
0.62%? As in 0.0062 of the total?
(Score: 3, Informative) by c0lo on Thursday July 06 2017, @11:34AM (6 children)
No added sea height, it's an iceberg. It it already floating and Archimedes eureka-ed it's dislocating a volume of water equal in weight with its own.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by kaszz on Thursday July 06 2017, @11:58AM (5 children)
It was not an iceberg when it was attached to the rest of the ice continent. And when it melts enough to let the top slip down below the water level the sea level will increase additionally too.
(Score: 1, Informative) by Anonymous Coward on Thursday July 06 2017, @12:35PM (3 children)
The volume shrinks when ice melts. You are clueless.
(Score: 2) by kaszz on Thursday July 06 2017, @02:05PM (2 children)
Sure, but will it shrink enough to matter in relation to other factors?
(Score: 3, Informative) by MrGuy on Thursday July 06 2017, @04:49PM (1 child)
It will shrink exactly to occupy the volume it currently displaces.
A floating object displaces exactly enough water to exactly balance the object's weight. i.e. an object floats at a height where the volume of the submerged portion would, if completely filled with water, have the same weight as the whole floating object.
The "trick" here is that the weight of the water IN THE ICEBERG doesn't change when it melts. If you measured the weight of the iceberg before it melted, and measured the resulting water after it melted, they'd weigh the same. Which means that the pre-melted iceberg and the post-melted iceberg displace the exact same amount of water. So the melting of the iceberg won't affect the sea level any.
Now, if the iceberg shelf was NOT currently floating (e.g. it was a kind of ice bridge over the ocean that was sitting ABOVE where it would "naturally float"), then you'd be correct that the calving off of the iceberg WOULD raise sea levels when the iceberg entered the water for the first time. My understanding is that's not how the antarctic ice shelves work (which makes sense - a 125-mile long chunk of ice being held higher than gravity would tell it to my a 3-mile frozen section would be fighting TREMENDOUS leverage at the narrow attachment point, and would certainly have broken off by now).
(Note for nitpickers - Yes, I'm ignoring some factors that technically come into play here, for example of the salinity of the iceberg and the salinity of the water it floats in aren't equal, the difference in density WOULD have an impact. Also, as the water warms post-melting, it actually shrinks slightly (up to 4 degrees C), then starts expanding. Those are things that can be factored in once we're clear on the general principals.)
(Score: 2) by c0lo on Thursday July 06 2017, @06:10PM
(imagination running amok,'ey?)
How about a piece of ice sustained by the sea bottom all the size? Like sea frozen there, then snow piling on top until the weight is too much to allow the ice to float?
In the extreme case, make the initial sea depth being zero and have only snow piling on top and compacting as ice?
Sounds familiar? Those are glaciers. When they melt, the sea level rises. Like the Greenland icesheet meltdown [sciencemag.org]
(yes, one can imagine glaciers that are actually advancing in the sea without calving icebergs - too thick to start with when pushed by the ice sheet behind. Or just surface melting until lightweight to stat floating. In both cases, the sea level will grow because of the water displaced or the result of melting)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Informative) by c0lo on Thursday July 06 2017, @01:03PM
Do you know why is called a "shelf"? Because it's floating, even when attached to the land mass.
Don't confuse it with glaciers - true, glaciers give birth to ice shelves, but Larsen C was floating since a long time ago; the imminent calving won't change the sea level.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by aclarke on Thursday July 06 2017, @01:48PM (4 children)
Thank you. I saw "size of Delaware" and thought WTF. Then I saw 2,500 sq.mi and thought WTWTF.
None of that explains to me how many American football fields that is. The answer is 58,000 American football fields for anyone who is confused by all these other meaningless measurements.
(Score: 3, Interesting) by kaszz on Thursday July 06 2017, @02:19PM (3 children)
Whenever I see measurements like "American football field" it kind of implies the author is generally not worth any attention span or time. Its very origin implies people that spend more time on football than science and as such know less than those that do spend their attention on science.
The practical aspect is that every football field is slightly different and the measurement is very bigoted against people that don't involve themselves with that as they will not have a real life experience sufficiently internalized to matter. And measurements like square meter may be hard to grasp in the beginning but with time a person will get reference points and so can make sense of the abstract number. At this stage with the benefit that the measurement unit learned is consistent across nations and subjects.
(Score: 2) by FatPhil on Thursday July 06 2017, @03:09PM (1 child)
So, karma-whoring, let's call this school of icebergs (as it will whelp) nearly a third the area of Wales, and more than a fifth the area of Belgium.
South Americans - you're on you're own. Shall we call it an East Falkland, and if you can't relate to that, then don't even think of invading it!
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by darnkitten on Friday July 07 2017, @12:28AM
Converting into recognized scientific measurements---
Slightly more than .3 Waleses or .2 Belgiums, and slightly smaller than the East Falklands.
Based on Kaszz's calculations and a bit of internet searching, the meltwater would fill about 400 million Olympic sized swimming pools, the unmelted ice around 430 million.
Unfortunately, I was unable to determine how many Libraries of Congress could be filled, as I was able to find the number of volumes held by the LofC, but not the spatial volumes of the buildings themselves, nor even the average volume of the books therein.
(Score: 2) by aclarke on Thursday July 06 2017, @03:15PM
I modded your comment as informative, then decided to respond with a genuine thank-you. The football fields comment was meant as a joke.
(Score: 2) by MrGuy on Thursday July 06 2017, @04:35PM
Someone's got to translate that into fractions of the Empire State Buildings for me, which is the preferred standard New York City building of measure.
You can't tell me something is about "twice as tall as the building on the southeast corner of 47th and broadway" and expect it to mean something to me. We need standards here, people!