Climate graphic of the week: Iceberg break from Brunt Ice Shelf
Glaciologists are monitoring whether the mass is at risk of causing damage as it is carried by the current
Glaciologists have been closely observing the many cracks in the Brunt Ice Shelf for years, but in late 2019 a new rift was spotted.
Satellite imagery showed the crack cutting across the ice shelf towards another large crack, captured by the Copernicus Sentinel-1 mission as it also monitors for changes in ice dynamics, air and ocean temperatures.
Observations showed the region north of the new crack was the most unstable, according to the European Space Agency, and indicated it was moving at a rate of about 5m per day.
The crack was near an area where, Nasa reported, the flow of ice is “impeded by an underwater formation that causes pressure waves, crevasses, and rifts to form at the surface.”
Finally, in late February, the crack widened rapidly before the iceberg finally broke free from the rest of the 150m thick floating ice shelf, the ESA said. The agency was continuing to watch for further significant effects.
“Over the following weeks and months, the iceberg could be entrained in the swift southwesterly flowing coastal current, run aground or cause further damage by bumping into the southern Brunt Ice Shelf,” said Mark Drinkwater, the head of mission science at the ESA. “So we will be carefully monitoring the situation.”
The iceberg was dubbed A-74, based on the Antarctic quadrant in which it was sited. Even at 1270 square km, Nasa said the iceberg was dwarfed by the so-called A-68 which broke from the Larsen C Ice Shelf in 2017 and was five times the size.
The ESA noted the Brunt Shelf break did not pose a threat to the presently unmanned British Antarctic Survey’s Halley VI Research Station, which was repositioned in 2017 to a more secure location after the ice shelf was deemed unsafe.