Huge Antarctic Ice Shelf Headed for Collapse
The Wilkins Ice Shelf has been cracking in new places recently and images released by the European Space Agency show that it will probably very soon break off entirely. A 62 square mile piece broke off in May 2008.
Angelika Humbert of Muenster University stated, “During the last year the ice shelf has lost about 1800 square kilometers (694 square miles), or about 14 percent of its size.” The Wilkins Ice Shelf is currently about the size of Jamaica, though it has already been diminished by about 30 percent.
In January the British Antarctic Survey found that an array of very large ice chunks were breaking off and separating from the area. “The cracks in the Wilkins ice shelf and the chunks of ice that are splitting away from the ice-shelf….they’re kind of shopping mall chunks of ice and some are floating off into the ocean.” About 8 other such ice shelves there have been lost. At least one of them had been intact for approximately 10,000 years. Recent research has indicated that the loss of Antarctic ice shelves could actually shift the axis of the earth.
The Wilkins shelf is held together by a narrower strip of ice that has been thinning and growing weaker due to melting. Reportedly shaped like an hour glass, with the narrowest portion being the connecting bridge for the larger end pieces, the shelf is now estimated to collapse entirely very soon. The narrower part of the shelf has been estimated at 40 km wide down to 500 meters at the thinnest section. In 1950 the narrow connecting strip was 100 km wide.
The disintegration of such enormous masses of ice is thought to be indicative of the power of global warming to cause very disruptive, if not catastrophic change to the natural environment. One measurement that is tied to the loss of the ice shelves is the temperature increase in the area over the last fifty years of 5 degrees Fahrenheit.
Image Credit: National Ice and Snow Data Center
Other Images, Public Domain and NASA
The dude does bring up some valid points!
RT
http://www.privacy.at.tc
Just how does breaking off of pieces of the Wilkins ice shelf raise ocean levels. Would not the ocean level go down ever so slightly as the iceberg melted?
If you fill a glass with ice cubes to the top, then fill the glass with tap water to near the top and let it sit at room temperature for 24 hours – does the glass overflow?
Nuf Said?
Another way to see this effect is if you freeze water in a bottle. We all know that we have to leave some room for expansion or the bottle will burst as the water freezes.
Ice displaces more volume than water. So the only ice that adds to the volume of the water is any ice that is above the water – and we all know – that’s just the tip of the iceberg!
Interfacer.
A couple of important facts were left out of the article. That part of Antarctica with the Wilkins Ice Shelf includes a string of the most active volcanoes on that continent. The 5°F rise alluded to in the article is heavily biased by temperature sensors not far from the volcanic active area. If the temperature sensors on the Antarctic peninsula were removed, the remaining temperature sensors located elsewhere on the continent would show a distinct cooling trend over the past decade.
Nope … you have it wrong guys. a) Much of this water exists above sea level … therefore as it melts it … guess what? … runs INTO the sea, thus affecting water levels. b) the current ice sheet acts as a plug, stopping other land-bound glaciers from moving toward the coast and facing the same fate, thus also raising the ocean levels. At least that’s how it works with the Greenland glaciers, and I can only assume that it is a similar case in the Antarctic.
Or to put it another way … if you fill up a glass to the brim, then keep dumping ice cubes into it from the counter does it run over? ’nuff said.
OK, I’m not going to comment on other’s comments… it hurts to read them. However…
Yes, The melting of the ARCTIC ice won’t affect the sea levels, as that ice sheet is already floating within the ocean, and won’t displace volumes of water.
However, most of the ice in the ANTARCTIC sits ontop of a giant continental rock shelf ABOVE THE WATER LINE. So if that falls into the ocean, it’s like filling up the glass of water first, THEN putting the ice in, which therefore = overflow. Hence, the problem of rising sea levels.
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The glass analogy above is a useful one, but inaccurate. From what I understand the main problem with sea levels is not that these ice shelfs are breaking up–it’s that they hold land ice in place. When the ice shelfs are gone, the land ice falls into the water causing sea level to rise.
So to look at the glass of ice water analogy again, it’s as if the ice cubes are slowly melted overnight–and this causes someone to throw another handful of ice cubes on the top–and the glass overflows.
Hmmm, Had a look at my old atlas from the 70’s and antarctica had less ice then, than it does now. So I did a little research and it seems the glaciers and ice shelves have been increasing eratically since a huge melting back in the 1940’s. It seems ‘calving’, where vast areas of ice fall away usually precedes massive surges in glaciers and ice shelves.
Dynamics of Antarctic Glaciers in the 20th century can be found at http://www.cig.ensmp.fr/~iahs/redbooks/a208/iahs_208_0209.pdf and is an eight page PDF file which gives much more information.
The gentleman who wrote the above report is Russian – and, after doing their own research, the Russians don’t seem too bothered about climate change!! I wonder why?