Antarctica’s Amery Ice Shelf just calved it’s biggest iceberg in over 50 years. D28, as it’s called, covers an area of 1,636 sq km, slightly smaller than the Isle of Skye, in Scotland.
Because of its size, the berg will have to tracked and monitored as it could pose a hazard to shipping in future.
Amery calved a much bigger iceberg of 9,000 sq km in area, in the early 1960’. The third largest ice shelf in Antarctica, Amery is a key drainage channel for the east of the continent.
Prof Helen Fricker of the Scripps Institution of Oceanography told BBC News: ‘’The calving of bergs at the forward edge of the shelf is a very natural behaviour.’’ To balance the weight of snowfalls upstream, calving berg is how the ice streams maintain stability.
Expecting a calving event, scientists have been keeping an eye on an area known as “Loose Tooth”, just east of where the recent calving took place. Loose Tooth is a bit wobbly but still attached while D28 broke off instead. Prof Fricker described D28 as “the molar compared to a baby tooth.”
Prof Fricker’s prediction in 2002 that Loose Tooth would break off between 2010 and 2015 was not far off.
“I am excited to see this calving event after all these years. 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,” she said.
Fricker is convinced this event is not linked to climate change. Satellite data dating back to the 1990s has shown Amery mostly in balance with its surroundings, in spite of experiencing strong surface melt in summer.
“While there is much to be concerned about in Antarctica, there is no cause for alarm yet for this particular ice shelf,” Prof Fricker added.
Meanwhile, the Australian Antarctic Division will keeping a keen eye on their instrumentation in the area for any reaction by Amery to the event. The loss of such a big berg could change the stress geometry across the front of the ice shelf which could effect the
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 cracks and perhaps the stability of Loose Tooth. D28 is estimated to be about 210m thick with a weight of 315 billion tonnes of ice.
The US National Ice Center name the areas from a classification system which divides the Antarctic into quadrants.
The D quadrant covers the longitudes 90 degrees East to zero degrees, the Prime Meridian. This roughly covers Amery to the Eastern Weddell Sea.
A68, which broke away from the Larsen C Ice Shelf in 2017 currently covers an area more than three time bigger than D28.
Currents and winds will move D28 westwards and it will probably take quite a few years to break apart and melt entirely.