Huge ice tongue in Antarctica grows at astonishing rate annually

June 25th, 2008 - 3:15 pm ICT by ANI  

London, June 25 (ANI): Scientists have found that an ice structure, which has been referred to as a huge sea-ice tongue, that projects outwards from the West Ice Shelf in Antarctica, grows at an astonishing rate each year.

According to a report in New Scientist, the huge sea-ice tongue can be seen on the east side of Antarctica, and has been found to grow at an astonishing rate.

Pushing out around 3 centimetres of ice per second, the structure, that projects outwards from the West Ice Shelf, can grow to several hundred kilometres in just a few weeks.

Satellite images collected over several decades reveal that the tongue reached a record length of 800 km in May 2002, and covered an area of around 200,000 km2.

Such a large feature may represent an important biodiversity hotspot, according to the researchers who discovered it.

Similar features do occur elsewhere.

The Odden ice feature in the Greenland Sea, and the Drygalski Barrier, in the Antarctic, are both large ice tongues, but neither reaches the huge size of the West Ice Shelf tongue.

By studying images from between 1978 and 2004, Steve Rintoul at the Antarctic Climate & Ecosystems Cooperative Research Centre in Hobart, Australia, and colleagues, found that the feature grows during the Antarctic winter months in most years.

Later in the winter, shore ice obscures the tongue, but it emerges once more as the surrounding ice retreats, before finally melting away around January.

To find out what causes the ice tongue to grow to such huge size, the researchers analysed local wind and water-current data.

They concluded that ice forming around the mainland gets drawn out to sea by a sharp northward turn of the Antarctic Circumpolar Current.

This current normally flows around the Antarctic, but it is diverted away from the continent around 85deg east precisely where the tongue forms when it collides with the underwater Kerguelen Plateau.

Winds probably also contribute to the growth of the tongue and determine its size from year to year, said the researchers.

According to Ted Maksym, an ice expert with the British Antarctic Survey, the sea-ice tongue is a very interesting feature that highlights how quickly ice can change in volume. But, more research is needed to understand its relevance for wildlife.

We dont yet know how important the tongue itself is, in comparison to the currents and winds that form it, he says.

Rintoul hopes to learn more about the currents that push out the sea-ice tongue with the help of oceanographic sensors mounted on deep-diving elephant seals. (ANI)

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