It was the gap looked ’round the world.
In July 2017, after weeks of anticipation, a huge iceberg about the size of Delaware broke off from the Antarctic Peninsula (SN: 7/12/17). Satellite images show the orphan iceberg, known as A68, finally disintegrating in the Southern Ocean. Now researchers say they have put together the most powerful forces that led to that end-break.
Polar scientist Alex Huth of Princeton University and colleagues combined observations of the top of the iceberg with simulations of ocean currents and wind stress. Iceberg A68a, the largest remaining piece of the original berg, was caught in the course of the tug-of-war in the ocean, and the attack of opposing forces probably broke it apart through the ice, the team reports 19 Oct. Journal of Sciences.
After the A68 separation from the Larsen C ice shelf, researchers asked – what creatures live in the dark sea in the shadow of the ice (SN: 2/8/19). He took the same ice with him in time to move, staying in the neighborhood for about a year.SN: 7/23/18). By December 2020, satellite images show, the berg was clearly seen doing something and was only two-thirds of its original size.
New simulations suggest how A68a probably met its fate. On December 20, 2010, a long, thin “finger” at one end of the iceberg was moving into a strong, fast current. The rest of the ice remained outside the vein. The tension shook the berg, and within a few days the clipped finger broke off.
Shear stress is a previously unknown mechanism for large-scale iceberg fracturing, and is not represented in climate simulations, the team says. In the Southern Ocean, the melting of giant bridges can be a source of large amounts of cold freshwater reaching the surface of the ocean. That in turn can have a big impact on ocean circulation and global climate.
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