A massive iceberg in Greenland has sparked a scientific debate over its threat to shipping and possible links to global warming.

The largest iceberg in almost five decades split from Greenland's Petermann Glacier last Friday and is drifting towards the Arctic Ocean.

The Petermann glacier on Greeland's northwest coast. The photo was taken in 2009. A University of Delaware researcher reported Friday that an "ice island" four times the size of Manhattan calved off from Greenland's Petermann Glacier. The last time the Arctic lost such a large chunk of ice was in 1962. [gb.cri.cn]

A University of Delaware researcher said the ice island, about 30 kms long and 10 kms wide, is four times the size of Manhattan. The last time the Arctic lost such a large chunk of ice was in 1962.

While it is drifting slowly, it is now a constant reminder of the massive maritime tragedy which sank the once-thought unsinkable Titanic passenger liner in 1912.

Some experts worry the iceberg, which is too huge to be stopped, will pose a danger to oil platforms and shipping lanes, while others think the danger is not that immediate.

Researchers are trying to draw up the trajectory of the floating iceberg. They say it is drifting toward the Nares Strait which separates Greenland's northwestern coast and Canada's Ellsemere Island.

Trudy Wohlleben, a Canadian Ice Service forecaster who first discovered the ice-split on satellite images, said the ice island is likely to break down into smaller chunks before it reaches shipping lanes and could even become lodged in a channel or stuck to land.

But she also warned that these fragments could also be very big, considering the size of the ice island.