An iceberg floats in Andvord Bay, Antarctica. An iceberg the size of urban Sydney has broken away from east Antarctica, but not due to climate change, the Australian Antarctic Divisions (AAD) said. File photo

Canberra - An iceberg the size of urban Sydney has broken away from east Antarctica, but not due to climate change, the Australian Antarctic Divisions (AAD) said on Tuesday.

The 1,636-square-kilometre table iceberg "calved" from the Amery Ice Shelf, the third-largest on the ice continent, located between Australia's Davis and Mawson research stations, on September 26.

The iceberg, officially called D-28, separated from the front of the ice shelf, which scientists had been monitoring closely since the early 2000s, according to AAD, an Australian government agency.

It had been predicted that a large iceberg would break off between 2010-2015.

"We don't think this event is linked to climate change," said Helen Amanda Fricker, a professor at the US-based Scripps Institution of Oceanography. 

"It's part of the ice shelf's normal cycle, where we see major calving events every 60-70 years."

The last major calving event on the Amery Ice Shelf, which has an estimated floating ice area of 60,000 square kilometres, was in 1963-64.

"We knew it would happen eventually, but just to keep us all on our toes, it is not exactly where we expected it to be," Fricker said. 

Ice shelves are floating platforms of ice attached to coastlines.

Ben Galton-Fenzi, a glaciologist with AAD, said the fracture will not directly affect sea levels.

"But what will be interesting to see is how the loss of this ice will influence the ocean melting under the remaining ice shelf and the speed at which the ice flows off the continent," he said.

dpa