An enormous chunk has broken off the world’s largest iceberg, in a possible first sign the behemoth from Antarctica could be crumbling, scientists told AFP on Friday.

The colossal iceberg—which is more than twice the size of Greater London and weighs nearly one trillion tonnes—had largely stayed intact since it started slowly moving north in 2020.

It has been drifting toward the remote island of South Georgia in the South Atlantic, raising the prospect it could run aground in shallower water and disrupt feeding for baby penguins and seals.

But a chunk about 19 kilometers (12 miles) long has cleaved off.