British Antarctic Survey reported that an iceberg nearly the size of Greater London broke off the Brunt Ice Shelf in Antarctica on Sunday.

Scientists identified substantial breaches in the ice shelf a decade ago, but two big breakdowns have occurred in the last two years. The Brunt Ice Shelf is home to the BAS Halley Research Station, which glaciologists claim is safe.

The iceberg covers around 600 square miles (1550 square kilometers). According to the experts, this event was predicted and was not caused by climate change.

In a news release, Professor Dominic Hodgson, a BAS glaciologist, said, "This calving event has been expected and is part of the natural behavior of the Brunt Ice Shelf. It is not linked to climate change. Our science and operational teams continue to monitor the ice shelf in real-time to ensure it is safe, and to maintain the delivery of the science we undertake at Halley.” 

The calving occurs during summer with record-low sea ice extent in Antarctica.

Over the last two decades, Antarctica's sea ice extent has been like a roller coaster, swinging dramatically from record highs to record lows. In contrast to the Arctic, where scientists believe climate change is hastening its effects, Antarctica's sea ice extent is highly changeable.

According to satellite data dating back to 1978, the region was still producing record-high sea ice extent as recently as 2014 and 2015. Then it dropped precipitously in 2016 and has remained lower than average ever since.

Read next: Underwater volcano in Antarctica sets off 85,000 earthquakes