Mammoth iceberg could alter ocean circulation: study

Feb 25, 2010 by Marlowe Hood
Penguins (C) drift on an ice floe beneath a cathedral iceberg in the Southern Ocean in the Australian Antarctic Territory in 2006. An iceberg the size of Luxembourg knocked loose from the Antarctic continent earlier this month could disrupt the ocean currents driving weather patterns around the globe, researchers said Thursday.

An iceberg the size of Luxembourg knocked loose from the Antarctic continent earlier this month could disrupt the ocean currents driving weather patterns around the globe, researchers said Thursday.

While the impact would not be felt for decades or longer, a slowdown in the production of colder, dense water could result in less temperate winters in the north Atlantic, they said.

The 2550 square-kilometre (985 square-mile) block broke off on February 12 or 13 from the Mertz Glacier Tongue, a 160-kilometer spit of protruding into the Southern Ocean from East Antarctica due south of Melbourne, researchers said.

Some 400 metres (1300 feet) thick, the iceberg could fill Sydney Harbour more than 100 times over.

It could also disturb the area's exceptionally rich biodiversity, including a major colony of emperor penguins near Dumont d'Urville, site of a French scientific station, according to the scientists.

"The ice tongue was almost broken already. It was hanging like a loose tooth," said Benoit Legresy, a French glaciologist who has been monitoring the Metz Glacier via satellite images and on the ground for a decade in cooperation with Australian scientists.

The billion-tonne mass was dislodged by another, older iceberg, known as B9B, which split off in 1987.

Jammed against the Antarctic continent for more than 20 years, B9B smashed into the Metz tongue like a slow-motion battering ram after it began to drift.

Both natural cycles and manmade contribute to the collapse ice shelves and glaciers.

Tide and constantly beat against exposed areas, while longer summers and rising temperatures also take a toll.

"Obviously when there is warmer water, these ice tongues will become more fragile," said Legresy, who works at the Laboratory for Geophysics and Oceanographic Space Research in Toulouse, southern France.

The Metz Glacier Tongue, fitted with GPS beacons and other measurement instruments, could provide crucial insights into how these influences should be apportioned.

"For the first time, we will have a detailed record of the full cycle of a major calving event -- before, during and after," he said.

Since breaking off, the iceberg -- along with the newly mobile B9B, which is about the same size -- have moved into an ajoining area called a ploynya.

Distributed across the Southern Ocean, ploynyas are zones that produce dense water, super cold and rich in salt, that sinks to the bottom of the sea and drives the conveyor-belt like circulation around the globe.

If these icebergs move east and run aground, or drift north into warmer climes, they will have no impact on these currents.

"But if they stay in this area -- which is likely -- they could block the production of this dense water, essentially putting a lid on the polynya," Legresy explained.

The Metz Glacier Polynya is particularly strong, and accounts for 20 percent of the "bottom water" in the world, he added.

Eventually, the icebergs will die a natural death, but their lifespan depends on where they go.

Adrift, they could melt in a could of decades. If they remain lodged against the Antarctic landmass, they could persist far longer.

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freethinking
1.7 / 5 (18) Feb 25, 2010
Both natural cycles and manmade climate change contribute to the collapse ice shelves and glaciers.

Yea right, blame AGW. I believe it was Atlantian who contributed to the collapse of the ice shelves using their spaceships. Please anyone disprove this theory.
Megadeth312
3.2 / 5 (11) Feb 25, 2010
Both natural cycles and manmade climate change contribute to the collapse ice shelves and glaciers.

Yea right, blame AGW. I believe it was Atlantian who contributed to the collapse of the ice shelves using their spaceships. Please anyone disprove this theory.


Why? Sounds solid to me =P
Parsec
3.9 / 5 (11) Feb 25, 2010
Anything that raises the temperature contributes to the collapse freethinking. Any type of climate change. Even if you don't think AGW is correct, and believe that the rapid run up in global temps is being caused by little men in spaceships, any increase in temp caused by man-made climate change (or anything else) would be a contributer. I would suggest that you not get your panties in an uproar just because they didn't also mention spaceships.
vanderMerwe
3.7 / 5 (3) Feb 26, 2010
I think that a butterfly could fart and all the hysterical watermelons would claim that it would "disrupt the ocean currents driving weather patterns around the globe"
mary_hinge
4.5 / 5 (2) Feb 26, 2010
Parsec- your comment about climate septics thinking that spacemen might be responsible is not too far off the mark...apparently they think there are "Astrological....dynamics" too.
Checkout this South Dakota House resolution 1009. The telling quote (my emphasis)is:
" 2) That there are a variety of climatological, meteorological, ASTROLOGICAL, thermological, cosmological, and ecological dynamics that can effect world weather phenomena and that the significance and interrelativity of these factors is largely speculative"
I'd love to know what they mean by Thermological!
rgw
4.3 / 5 (3) Feb 26, 2010
This 'mammoth' iceberg is approximately 1000 square miles and maybe a mile thick. These dimensions make this iceberg an insignificant speck in relation to anything in Anarctica and even less significant in comparison to the vast extent of the oceans. Even the 'tiny' Southern Ocean is 7.8 MILLION square miles and 2-3 miles deep. Anarctica is 5.4 million square miles covered in ice at least a mile thick! This iceberg's actual impact on anything is a tiny fraction of 1 percent (approx 2/100 of 1 percent)Even less when factored against the vast amount of water in the oceans.
DGBEACH
4 / 5 (5) Feb 26, 2010
Since it no longer is attached to Antarctica, isn't it now there for the taking?...all that fresh water...with changing rain patterns around the world and whole societies soon to be out of water, why couldn't we harvest the ice for our consumption?
joefarah
2 / 5 (8) Feb 26, 2010
"Both natural cycles and manmade climate change contribute to the collapse ice shelves and glaciers"

I'm assuming this means, 99.9999% natural cycles and .00001% manmade CC. That would satisfy the "both" "contribut[ing]" criteria.