Foruroligende fra Antaktis - Observert fra bl.a. en NASA DC-8-72 - BBC

Larsen ice crack continues to open up

By Jonathan Amos BBC Science Correspondent

• 9 hours ago

The crack that looks set to spawn a giant iceberg in the Antarctic has continued to spread.

The rift in the Larsen C Ice Shelf has grown a further 10km since 1 January.
If the fissure propagates just 20km more, it will free a tabular berg one-quarter the size of Wales.
That would make it one of the biggest icebergs ever recorded, according to researchers at Swansea and Aberystwyth universities, and the British Antarctic Survey.
News of the lengthening crack in the 350m-thick floating ice shelf on the eastern side of the Antarctic Peninsula comes from the EU’s Sentinel-1 satellite system.

Comprising two spacecraft, this orbiting capability can continuously monitor Larsen C no matter what the weather is doing because its radar sensors see through cloud.
Their data indicates the fissure now extends for some 175km. But just how long it will take before the 5,000 sq km block finally breaks free is anyone’s guess, says Swansea's Prof Adrian Luckman.
"The rift tip has just entered a new area of softer ice, which will slow its progress," he told BBC News.
"Although you might expect any extension to hasten the point of calving, it actually remains impossible to predict when it will break because the fracture process is so complex.
"My feeling is that this new development suggests something will happen within weeks to months, but there is an outside chance that further growth will be slow for longer than that.
"Sometimes rift growth is triggered by ocean swell originating elsewhere, which is also hard to predict."

Image copyright NASA

Image caption Images taken in November last year illustrate the scale of the rift

When the berg splits away, interest will centre on how the breakage will affect the remaining shelf structure.
The Larsen B Ice Shelf further to the north famously shattered following a similar large calving event in 2002.