Scientists have made an alarming new discovery in the Antarctic: the rift in the Larsen C Ice Shelf has expanded by 10 kilometers since the beginning of this year, according to reports. And if it grows by another 20 kilometers, it will create a huge iceberg that is a quarter of the size of Wales, making it one of the biggest icebergs recorded in history.

The ice shelf, which is more than a thousand feet thick, is on the eastern side of the Antarctic Peninsula. The EU’s Sentinel-1 satellite system is recording the lengthening craft. It contiuously monitors Larsen C with radar sensors, and now reports that the crack is 175 kilometers long, but it’s hard to tell when exactly it will break off.

The iceberg could affect the rest of the ice shelf structurally when it breaks away.