In July 2017, iceberg A-68 broke off from the Larsen C Ice Shelf along the east coast
Over the course of three and a half years, the iceberg broke apart and melted, leaving a mark in the ocean environment, especially near the remote island of South Georgia.
“Icebergs are a source of cold, fresh water.and nutrients in the Southern Ocean. However, where and how much iceberg 'content' is released is not very well understood and is not yet included in ocean models, especially for the largest icebergs,” explains Anne Braakmann-Folgmann, a doctoral student at the University of Leeds.
Credit: NASA Earth Observatory
Braakmann-Folgmann and his colleagues decidedmap the A-68A's journey. It received a new name after several pieces broke off from the massif. The researchers used satellite data to document changes in the thickness, area, volume and mass of the iceberg from the time it broke away from the ice shelf in July 2017 until it began to rapidly disintegrate in January 2021.
Credit: NASA Earth Observatory
The maps above show where and whenThe iceberg thinned as it drifted north from the Weddell Sea to the Scotia Sea, as did the thickness of the ice mass. As the iceberg drifted north, it encountered higher air and water temperatures, accelerating melting. By January 2021, as the iceberg approached South Georgia, its average thickness had decreased to 168 meters.
About 85% of the iceberg is belowsurface of the water, making measurements difficult. However, to compile the maps, scientists used data from NASA's Ice, Cloud and Land Elevation Satellite 2 (ICESat-2) and the European Space Agency's CryoSat-2. These laser and radar altimeters respectively help determine the distance from the satellite to the iceberg surface and to the surface. seas. The difference between these measurements is known as an iceberg's "freeboard"—the height of the ice above the water. Scientists can then convert this height into thickness, taking into account the density of the mass, the layer of snow above and the surrounding seawater.
Studies have shown that the melting peak occurredto South Georgia, where scientists estimate that 152 billion tons of fresh water entered the ocean in three months—the equivalent of 61 million Olympic swimming pools. Experts are still investigating the impact of all this fresh water on the properties of the local ocean.
Other ice losses occurred when large pieces broke off from the sides of the iceberg. Thinning and fragmentation increased as the massif drifted north.
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