It was the crack seen all over the world.
In July 2017, after weeks of anticipation, a massive iceberg the size of Delaware separated from the Antarctic Peninsula (Serial number: 12/7/17). Satellite images show that the orphaned iceberg, known as A68, eventually disintegrated in the Southern Ocean. Now, researchers say they have assembled the powerful forces that led to that final breakout.
Polar scientist Alex Huth of Princeton University and colleagues combined observations of iceberg drift with simulations of ocean currents and wind stress. Iceberg A68a, the largest remaining chunk of the original iceberg, was caught in a tug-of-war of ocean currents, and the tension of those opposing forces probably separated the icebergthe team reports on October 19 at Progress of science.
After the separation of A68 from the Larsen C ice shelf, researchers had questions, such as what creatures live at the bottom of the sea in the dark shadow of the ice (Serial number: 8/2/19). As for the iceberg itself, it is took a while to get movingstaying in the neighborhood for about a year (Serial number: 07/23/18). By December 2020, satellite images show, the iceberg had clearly seen some action and was only two-thirds its original size.
The new simulations suggest how A68a likely met its fate. On December 20, 2020, the long, thin “finger” at one end of the iceberg slid into a strong, swift current. The rest of the ice was left out of the current. The stress opened a crack in the iceberg and the finger was severed and broke within a few days.
Shear stress is a previously unknown mechanism for the breakup of large icebergs and is not represented in climate simulations, the team says. In the Southern Ocean, the melting of huge icebergs can be a great source of cold fresh water to the ocean surface. That, in turn, can have a huge impact on ocean circulation and global climate.