| Iceberg A-68 | |
| Type: | Tabular iceberg |
| Map: | Antarctica |
| Part Of: | Larsen C ice shelf (originally) |
| Water Bodies: | South Atlantic |
| Area: | 5800km2 (at break) |
| Length: | 175km (109miles) (at break) |
| Width: | 50km (30miles) (at break) |
Iceberg A-68 was a giant tabular iceberg adrift in the South Atlantic, having calved from Antarctica's Larsen C ice shelf in July 2017.[1] [2] [3] By 16 April 2021, no significant fragments remained.
With a surface area of 5800km2, twice the size of Luxembourg, over a quarter the size of Wales, and larger than Delaware,[4] it was one of the largest recorded icebergs, the largest being B-15 which measured 11000km2 before breaking up. The calving of reduced the overall size of the Larsen C shelf by 12 percent.[5]
Historical data shows that many icebergs that break off from the Antarctic Peninsula reach South Georgia and the South Sandwich Islands.[6]
The name was assigned by the US National Ice Center. It broke into parts with the mother berg dubbed . The larger child icebergs were designated in order of birthing, as,,,,, and in January 2021, splitting almost in half to birth . On 30 January 2021, Iceberg broke into other icebergs called,,,,, .
was part of Larsen C, a section of the Larsen Ice Shelf. Scientists found the crack beginning to form in November 2016. Scientists assess that "didn't just break through in one clean shot, [but] it formed a lace-network of cracks first." The resulting iceberg was around 175km (109miles) long and 50km (30miles) wide, 5800km2 in area, 200m (700feet) thick and weighed an estimated one trillion tonnes.[7] [4]
Satellite images from the ESA and EU's Copernicus Program show that as the iceberg moved, it was gradually shrinking and splintering, forming more icebergs in the process.[8]
Scientists are looking into the possibility of the ice shelf collapsing as a result of the split with, or whether the iceberg was the "cork" for Larsen C that allows ice to flow more freely into the sea, thereby contributing to rising sea levels.[9]
Post November 2017, satellite images showed that was slowly drifting northward, with a widening gap to the main shelf. The gap was approximately 5km (03miles) wide and contained a thin layer of loose, floating ice and a cluster of more than 11 'smaller' bergs, one much larger than the others.
A British expedition on intended to sample the marine life at the cleavage line in March 2018, but had to turn back due to thick sea ice.[10] During 2018, continued to drift northwards.[11] In 2018 or 2019, a large chunk almost broke off and was named, with the mother iceberg now being .[12]
On 6 February 2020, began moving into open waters.[13] On 23 April 2020, a chunk measuring about broke off the iceberg and was named .[14]
On 4 November 2020, it was reported that was approaching South Georgia Island and that there was a strong possibility that the iceberg might run aground on the shallower continental shelf near the island, posing a grave threat to local penguins and seals. A spokesman from the British Antarctic Survey stated that the iceberg could become stuck for a number of years, causing disruption to wildlife and the local fishing industry.[15]
On 9 December 2020, the Royal Air Force released video footage of, 150 km off South Georgia. The RAF conducted reconnaissance flights over the iceberg on 18 November and 5 December 2020.[16]
, a part of the iceberg was just from South Georgia, but the concern seemed to have lessened. National Geographic reported that "[s]cientists expect the iceberg ... to either anchor in the shallow waters around the island or move past it in the coming days."[17] On this date it was also reported that a corner had been knocked off, most likely due to impact with the seabed.[18] The new free floating iceberg has been designated .[19]
On 22 December 2020, images from ESA's Sentinel-1 radar satellite showed that had experienced a major break-up. Two of the larger fragments were named and .[20] A modeling study demonstrated that this break-up was likely triggered when part of A-68A became positioned within stronger ocean currents than the rest of the berg, generating enough tension along its body to break it into pieces.[21]
On 28 January 2021, Sentinel-1 discovered that the southern third of had broken away. The new segment was named, with an area of around 950km2. The imagery shows these two bergs around 135 km south-east of South Georgia drifting close together.[22] [23]
On 30 January 2021, Iceberg broke up into other icebergs called,,,,, and .[24] [25]
On 15 February 2021, it was reported that British scientists had arrived at the remnants of, and had deployed a robotic glider to measure seawater salinity, temperature and chlorophyll close to the remaining blocks of ice to ascertain effects on local marine life.[26]
On 16 April 2021, the largest fragment was down to 3 nautical miles in length and the U.S. National Ice Center, which names, tracks, and documents Antarctic icebergs, discontinued tracking,[27] as the Center only studies icebergs that are at least 20 sq. nautical miles, or that measure 10 nautical miles on the longest axis.[28]