One of the biggest icebergs ever recorded, a gigantic slab roughly the size of East Anglia, is about to float loose into the world's oceans, scientists say. The iceberg, 183 miles long and 22 miles wide, is breaking away from the Ross ice shelf in Antarctica, the region of the continent closest to New Zealand.
The ice shelf regularly sets frozen chunks adrift, and the appearance of what is effectively a new floating island is not thought to be connected to global warming. But the size of this berg is exceptional.
"This is a very big iceberg, close to a record if not a new record," said Matthew Lazzara, a scientist at the Antarctic Meteorological Research Centre in Wisconsin. "It's not often that you see them of this magnitude."
Dr David Vaughan, a glaciologist at the British Antarctic Survey, said: "It may not be the biggest, but it's certainly a big one. It's not a climate warming thing. This is what ice shelves do."
The shelf splits when the steady build-up of fresh ice from glaciers and snowfalls makes its size unsustainable. Antarctica produces a massive iceberg once every ten years or so, although this may be the biggest since humanity began scientific monitoring of the region.
Big icebergs can eventually drift as far north as Cape Town, but there is no immediate emergency for shipping. Their progress is stately. Assuming the new monster berg, which is about 230m (750ft) thick, manages to clear the sea floor, it will circle Antarctica at a gentle one knot for up to 20 years before drifting north into warmer waters and starting to melt.
"From that moment we start measuring its life span in months rather than years or decades," said Dr Vaughan. "It's anybody's guess where the last bits of it will end up."
He was sceptical about the dangers to shipping the iceberg might pose. "It's hard to hit an iceberg that stands 100ft out of the water, is hundreds of kilometres long and has been mapped ever since it was born," he said.
The real menace to vessels like the Titanic, which sank after hitting an iceberg in 1912, is from waterlogged icebergs known as "growlers", which lurk low in the water.
The new iceberg is not thought likely to be carrying much in the way of wildlife with it, although as it scrapes the seafloor it will churn up clouds of microscopic sea creatures which draw scavenging seabirds like the albatross.
Dr Vaughan declined to be stirred by the sheer scale of the iceberg. "That's kind of Antarctic trainspotting," he said. "It doesn't do any harm, but don't expect me to put a bobble hat on and worry about it."
In 1987, an iceberg with an area of 2,450 square miles broke from the Ross ice shelf. It had a mass of around 1.4 trillion tonnes and could have supplied everyone in the world with 240 tonnes (2.4m litres) of pure drinking water. The largest ever iceberg is thought to be a 1956 behemoth, which measured 207 miles long by 62 miles wide.
