One of the largest icebergs on record has broken away from an ice shelf in Antarctica, scientists have announced.
A huge crack in the Larsen C Ice Shelf had left a vast iceberg weighing more than a trillion tonnes "hanging by a thread".
But now the rift has finally completed its path through the ice, researchers monitoring the berg have said.
The 5,800 square kilometre (2,200 square mile) mass has now calved, the team from the Swansea University-led Midas project said.
Data from Nasa's Aqua MODIS satellite detected the final breakthrough between Monday and Wednesday.
The calving of the iceberg, which is likely to be named A68, reduces the size of the Larsen C Ice Shelf by around 12% and will change the landscape of the Antarctic Peninsula forever, the scientists said.
Professor Adrian Luckman of Swansea University, lead investigator of the Midas project, said: "We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few kilometres of ice.
"We will continue to monitor both the impact of this calving event on the Larsen C Ice Shelf, and the fate of this huge iceberg.
"The iceberg is one of the largest recorded and its future progress is difficult to predict. It may remain in one piece but is more likely to break into fragments.
"Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters."
Although the iceberg weighs a trillion tonnes, it was already floating before it calved away so will have no immediate impact on sea level.
While the researchers said the calving was a "natural event", it put the ice shelf in a vulnerable position.
There are concerns that Larsen C could follow the example of its neighbouring ice shelf Larsen B, which disintegrated in 2002 after a similar event.
If the shelf loses much more area, it could result in glaciers which flow off the land behind speeding up their path to the ocean, which could have an eventual impact on sea levels - though at a very modest rate, the scientists said.