It was the rift watched ‘round the world.
After weeks of anticipation, a huge iceberg the size of Delaware was discovered in July 2017. Split from the Antarctic Peninsula (SN: 7/12/17). Satellite images reveal that the Southern Ocean eventually disintegrated the abandoned iceberg A68. Researchers now believe they know the forces that caused that final breakup.
Polar scientist Alex Huth of Princeton University and colleagues combined observations of the iceberg’s drift with simulations of ocean currents and wind stress. Iceberg A68a, which is the largest remnant of the original, was captured in a tug-of war of ocean currents and the The iceberg was probably torn apart by the strain of these opposing forcesThe team reports on October 19th Science Advances.
After A68’s separation from the Larsen C ice shelf, researchers had questions — such as what creatures live on the seafloor in the ice’s dark shadow (SN: 2/8/19). The iceberg is itself a mystery. It took some time to get moving., who remained in the area for around a year.SN: 7/23/18). Satellite images from December 2020 show that the berg was only two-thirds its original size.
New simulations show that A68a likely met its end. On December 20, 2020, the long, slender “finger” at one end of the iceberg drifted into a strong, fast-moving current. The current did not affect the rest of the ice. The tension caused the berg to rift, and the finger was sheared off. Within a few days it broke apart.
Shear stress is a previously unknown mechanism for large iceberg breakup, and isn’t represented in climate simulations, the team says. The Southern Ocean’s melting of huge bergs can provide freshwater sources for the ocean surface. This, in turn can have a huge impact on the ocean circulation as well as the global climate.
