The calving of the 1,636 sq km iceberg is not linked to climate change, scientists say, but could speed up further melting
Lisa Cox – The Guardian
A gigantic iceberg about the size of greater London has calved from the Amery ice shelf in east Antarctica, according to expert monitors.
The tabular iceberg, officially named D-28, separated from the ice shelf on 26 September. The iceberg is 1,636 square kilometres in size, or about 50 x 30km, the Australian Antarctic Division said.
Ice shelves are platforms of floating ice that form where the Antarctic ice sheet meets the ocean. Working in a similar way to architectural buttresses, they hold back the flow of the grounded ice.
The Amery ice shelf has an estimated floating ice area of 60,000 sq km and water penetrates over 550km underneath it.
It is the first major calving event on the Amery ice shelf since 1963-64 although scientists said they did not believe it was linked to climate change.
The calving occurred next to a location known as the “loose tooth” that scientists had been watching because the ice appeared to be precariously attached.
Scientists from the Australian Antarctic program, the Institute of Marine and Antarctic Studies and Scripps Institution of Oceanography have been monitoring the site for almost 20 years.
Helen Amanda Fricker, a Scripps professor, said scientists first noticed a rift at the front of the ice shelf in the early 2000s and had predicted a large iceberg would break off between 2010 and 2015.
“I am excited to see this calving event after all these years,” she said.
“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.”
The Amery ice shelf is the third largest in Antarctica and is located between Australia’s Davis and Mawson research stations.
Researchers have been studying the ice shelf since the 1960s and currently have instruments on the ice that are measuring the impact of ocean melt and ice flow.
Fricker said: “It’s part of the ice shelf’s normal cycle, where we see major calving events every 60-70 years.”
Ben Galton-Fenzi, a glaciologist with the Australian Antarctic Program, said the calving was detected through satellite imagery.
“The calving will not directly affect sea level, because the ice shelf was already floating, much like an ice cube in a glass of water,” he said.
“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.”