One of the largest icebergs in history is set to be created when a vast expansion of ice breaks away from Antarctica.
The rapid growth of a rift in December has left only 20km of ice preventing the 5,000 sq km iceberg from floating clear in early 2017.
The iceberg will be almost four times the size of Cornwall (1,349 sq km) and nearly as big as Yorkshire (6,066 sq km).
- Video shows Nasa's air surveys of the region (no sound)
The breakaway is set to occur on the most northern major shelf in Antarctica, Larsen C, which floats at the edge of the western section of the world's most southerly continent.
UK-based scientists who are researching the effects of a warming climate on the 350m-thick Larsen C ice shelf said the event will "fundamentally change the landscape of the Antarctic Peninsula".
The breakaway is expected to make the whole of the shelf vulnerable.
The Larsen C ice shelf has been watched closely by Nasa and scientists at the Swansea-based Project MIDAS since the Larsen A ice shelf collapsed in 1995 and the Larsen B ice shelf rapidly broke up seven years later.
A statement on the Project MIDAS website said: "Larsen C may eventually follow the example of its neighbour Larsen B, which disintegrated in 2002 following a similar rift-induced calving event."
However, the project team said the event will be geographical rather than climate-based and is unlikely to alter sea levels in the short term.