English: Two Sentinel-1 radar images from 7 and 14 April 2017 were combined to create this interferogram showing the growing crack in Antarctica’s Larsen-C ice shelf.

Polar scientist Anna Hogg said: “We can measure the iceberg crack propagation much more accurately when using the precise surface deformation information from an interferogram like this, rather than the amplitude – or black and white – image alone where the crack may not always be visible.”
When the ice shelf calves this iceberg it will be one of the largest ever recorded – but exactly how long this will take is difficult to predict. The sensitivity of ice shelves to climate change has already been observed on the neighbouring Larsen-A and Larsen-B ice shelves, both of which collapsed in 1995 and 2002, respectively.
These ice shelves are important because they act as buttresses, holding back the ice that flows towards the sea.

The Copernicus Sentinel-1 two-satellite constellation is indispensable for discovering and monitoring events like these because it delivers radar images every six days, even when Antarctica is shrouded in darkness for several months of the year.