A BLOCK OF ICE more than 1,500 square kilometres in area has broken off the Amery Ice Shelf in Antarctica. But researchers say the production of this iceberg, called D28, is not due to climate change, however it could speed up further melting.
The iceberg, about the size of greater London, officially named D-28, separated from the ice shelf on 26 September. The iceberg is 1,636 square kilometres in size, about 210m thick and contains some 315 billion tonnes of ice as reported by the Australian Antarctic Division.
The phenomenon called ice calving, the breaking away of a mass of ice from a glacier, iceberg etc is part of the ice shelf’s normal cycle. Ice calving events occur naturally every 60-70 years.
This recent occurrence is the first major calving event on the Amery ice shelf since 1963-64. 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.
The Amery ice shelf is the third largest in Antarctica and is located between Australia’s Davis and Mawson research stations.
Ben Galton-Fenzi, a glaciologist with the Australian Antarctic Program, noted “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,”
However, it’s possible the loss of such a big berg will change the stress geometry across the front of the ice shelf. This could influence the behaviour of cracks, and even the stability of the area.
Additionally the scale of the berg means it will have to be monitored and tracked because it could pose a future hazard to shipping.
In 1960s Amery calved a bigger iceberg which was an incredible 9,000 sq km in area.
Amery is the third largest ice shelf in Antarctica, and is a key drainage channel for the east of the continent.
The shelf is essentially the floating extension of a number of glaciers that flow off the land into the sea. Losing bergs to the ocean is how these ice streams maintain equilibrium, balancing the input of snow upstream.
D28 will be carried westward by nearshore currents and winds. It’s estimated to take several years for it to break apart and melt completely.