A LONE iceberg that drifted from Antarctica to Macquarie Island has started breaking up in the warmer water, with ice chunks washing up on the Tasmanian island's shoreline.
The iceberg is the first such sighting at Macquarie station since 2009 and sits about 4-5km off the coast, with several blocks of ice yesterday washing up on West Beach.
Antarctic Climate and Ecosystems CRC glaciologist Dr Jan Lieser said the iceberg likely came from East Antarctica, possibly from the Cooperation Sea.
The sea is north of the Amery Ice Shelf and west of Davis Station, 4200km from Macquarie Island.
Dr Lieser said satellite data couldn't spot the iceberg due to cloud cover and its size, which he estimated was about 50m-long on inspection of photos.
He added it would have lost 80 per cent of its mass due to contact with warmer water after escaping the Antarctic Circumpolar Current, but that it may not melt completely for months.
"It's not drifting at great speeds but it would be out of sight [of the island] by the end of the week or early next week," Dr Lieser said.
"It's on an eastern trajectory ... due to the wind and currents. It may pass through the Pacific [Ocean] below New Zealand."
Dr Lieser added seeing an iceberg so far north only happened every 10-15 years and he did not expect similar occurrences more frequently.
"It was carried by winds and waves," he said.
"Modelling is trying to understand how long they drift and last ... the bigger the iceberg, the longer it survives."
Macquarie station leader Kyle Williams said researchers could no longer see the iceberg out to sea due to fog, but they hoped to get a better idea of its movement when the weather cleared.
Update your news preferences and get the latest news delivered to your inbox.