On March 15, 2022, the Conger ice shelf in East Antarctica – a floating platform the size of Rome – will break away from the continent. Since the beginning of satellite observations in the 1970s, the shelf’s tip has been disintegrating into icebergs in a series of calving events, as glaciologists call them.
Conger has already been reduced to a 50km-long, 20km-wide strip connected to Antarctica’s vast continental ice sheet at one end and ice-covered Bowman Island at the other. Two calving events on March 5 and 7 further reduced it, separating it from Bowman and precipitating its final collapse a week later.
What triggered the collapse of Conger ice shelf?
The world’s largest ice shelves surround Antarctica, extending the continent’s ice sheet into the icy Southern Ocean. Smaller ice shelves can be found in Greenland, northern Canada, and the Russian Arctic where continental ice meets the sea. They can control the loss of ice from the interior of the sheet into the ocean by limiting the amount of grounded ice that flows upstream. When an ice shelf, such as Conger, is lost, the grounded ice that was previously held behind the shelf may begin to flow faster as the restraining force of the ice shelf is lost, resulting in more ice tumbling into the ocean.
Because they buttress the upstream flow of ice from the bordering ice sheet, ice shelves are sometimes referred to as Antarctica’s “safety band.” Little of the Antarctic ice sheet melts near the surface, where snow accumulates. Instead, the majority of the continent’s ice is lost through calving and melting along the undersides of floating ice shelves.
What does the collapse entail?
Parts of ice shelves break and detach naturally: ice shelves generally go through cycles of slow growth punctuated by isolated calving events. However, in recent decades, scientists have observed several large ice shelves completely disintegrate.
It is too early to say what caused the Conger ice shelf to collapse, but it does not appear to have been caused by melting at the surface – there are no signs of any ponds atop the ice shelf. The most recent series of events also preceded the March 18 record high air temperatures in Antarctica.