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Iceberg the size of Luxembourg dislodged
28 febrero 2010, 12:51 am
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Massive Iceberg Collision Could Alter Ocean Currents

A 60-mile-long iceberg roughly the size of Luxembourg shaved off a new iceberg after crashing into a glacier.

Fri Feb 26, 2010 08:40 AM ET | content provided by Owen Pye, Associated Press

THE GIST:

  • A giant iceberg struck a glacier in Antarctica, displacing another block of ice.
  • The new iceberg holds roughly the equivalent of a fifth of the world’s annual total water usage.
  • The iceberg has been nuzzling and shifting alongside the glacier for about 18 years before this month’s dislodging.

A massive iceberg struck Antarctica, dislodging another giant block of ice from a glacier, Australian and French scientists said Friday.

The two icebergs are drifting together about 62 to 93 miles (100 to 150 kilometers) off eastern Antarctica following the collision on Feb. 12 or 13, said Australian Antarctic Division glaciologist Neal Young.

“It gave it a pretty big nudge,” Young said of the 60-mile (97-kilometer) -long iceberg, about the size of Luxembourg, that collided with the giant floating Mertz Glacier and shaved off a new iceberg. “They are now floating right next to each other.”

The new iceberg is 48 miles (78 kilometers) long and about 24 miles (39 kilometers) wide and holds roughly the equivalent of a fifth of the world’s annual total water usage, Young told The Associated Press.

The iceberg that hit the Mertz Glacier is called B9B and had broken free from another part of Antarctica in 1987. It has been nuzzling and shifting alongside the Mertz for about 18 years before this month’s dislodging, said Benoit Legresy, a researcher with the LEGOS laboratory for geophysical studies in Toulouse, France.

“It was a slow process,” Legresy said. He said B9B was “sitting there, it must have been pushed and pulled by the current every day and used as a hammer to bang on the other one by the ocean currents.”

The dislodging occurred because of the iceberg’s latest location and water that had warmed during Antarctica’s summer, leaving less sea ice, Legresy said.

Some experts are concerned about the effect of the massive displacement of ice on the ice-free water next to the glacier, which is important for ocean currents, while others are less concerned.

Experts say this type of iceberg calving happens from time to time and these are not record large icebergs.

This area of water had been kept clear because of the glacier, said Steve Rintoul, a leading climate expert. With part of the glacier gone, the area could fill with sea ice, which would disrupt the sinking ability of the dense and cold water.

This sinking water is what spills into ocean basins and feeds the global ocean currents with oxygen, Rintoul explained.

As there are only a few areas in the world where this occurs, a slowing of the process would mean less oxygen supplied into the deep currents that feed the oceans.

“There may be regions of the world’s oceans that lose oxygen, and then of course most of the life there will die,” said Mario Hoppema, chemical oceanographer at the Alfred Wegener Institute for Polar and Marine Research in Germany.

But oceanographer Mike Meredith of the British Antarctic Survey said he doubts that will happen. There are other places around the world where oxygen sinks with cold water and for this to be a problem it would have to last over many years or decades.

The icebergs, weighing 860 billion tons and 700 billion tons respectively, are in water over the Antarctic Continental Shelf, Young said.

“We expect them to head west along the Antarctic coastline,” he said.

Young said it was not likely they would reach as far north as Australia, and noted icebergs move slowly.

Oxygen levels being fed into the world’s ocean currents are now changing “and the overturning circulation currents will respond to that change,” Rintoul said. Observing what happens “will … allow us to improve predictions of future climate change,” he added.

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Un iceberg del tamaño de Vizcaya se desprende de la Antártida

Los científicos temen que el bloque de hielo, procedente del glaciar Mertz, afecte a la circulación de los océanos y a la vida marina en la zona

EL PAÍS – Madrid – 26/02/2010

Una masa de hielo del tamaño de Vizcaya (2.500 kilómetros cuadrados) se ha desprendido de la lengua del glaciar Mertz en el Este de la Antártida al chocar con esta lengua un iceberg gigante a la deriva conocido como B-9B (de 97 kilómetros de longitud), según revelan las imágenes captadas por los satélites. La colisión se produjo hace tres semanas y ahora los dos icebergs flotan sin rumbo. Los científicos temen que este fenómeno afecte a la circulación de los océanos en todo el mundo y a la vida marina en la región.

La preocupación es que este desplazamiento masivo de hielo -el iceberg del tamaño de Vizcaya podría abastecer de agua a una tercera parte de la población mundial durante un año- altere la composición del agua del mar en la zona y el flujo normal del agua salada, densa y fría que transporta oxígeno a las corrientes oceánicas profundas. “La eliminación de esta lengua de hielo podría reducir el nivel de salinidad en el océano y afectar al ciclo de vida en el fondo del mar”, ha dicho Rob Massom, uno de los científicos responsables de la División Antártica Australiana, a la agencia Reuters. Según Mario Hoppema, oceanógrafo del Instituto Alfred Wegener para la Investigación Polar y Marina de Alemania, “como consecuencia de este fenómeno, puede haber áreas oceánicas que pierdan oxígeno y, consecuentemente, muera la vida marina que hay allí”.

A una mayor concentración de sal, mayor densidad del agua y un mayor flujo de la misma hacia el fondo del océano. La desaparición de ese gran bloque de hielo podría hacer descender ese flujo de agua, que se desparrama sobre la plataforma continental y conduce a ésta hacia el fondo del océano. Tal proceso actúa como una banda transportadora de las corrientes a los distintos océanos. Una alteración de ese flujo del agua hacia las profundidades modificaría el sistema de circulación de los océanos, que juega un importante papel en el clima global.

Massom ha subrayado que el desprendimiento de hielo del Mertz no está relacionado con el cambio climático, sino que tiene que ver con los movimientos naturales de las placas de hielo.

El iceberg B-9B es parte de otro más grande, de 5.000 kilómetros cuadrados, que se desprendió en 1987, convirtiéndose en una de las mayores masas de hielo de la Antártida. Este gigantesco iceberg estuvo a la deriva en dirección oeste antes de encallar en 1992. Recientemente, se soltó, quedando junto al Mertz.

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Comentario por Melanie

Thank you. It’s good to share important information.

Comentario por platicandocontarket




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