A giant sheet of ice measuring 260 square kilometres has broken off a glacier in Greenland, according to researchers at a US university.
Professor Andreas Muenchow of Delaware University says the
block, which separated from the Petermann Glacier on the north-west coast of Greenland, is the largest Arctic iceberg to calve since 1962.
There was enough fresh water locked up in it to "keep all US public tap water flowing for 120 days," Professor Muenchow says.
He says it's not clear if the event was due to global warming. Records on the seawater around the glacier have only been kept since 2003.
The ice island could become frozen in place over winter or escape into the waters between Greenland and Canada, the BBC reports. If it moves south, Professor Muenchow says, it could interfere with shipping.
Thousands of icebergs calve off Greenland's glaciers annually, but they are seldom so large.