How did it all start?
Large icebergs change the sea temperature around them and inject huge volumes
The A-68 is one of those icebergs.It broke off the Larsen Ice Shelf in July 2017 and has since moved steadily northward, away from the White Continent. Then its area was 5800 km² - twice as much as Luxembourg. Its size was 175 by 50 km, and its mass was a trillion tons. It is one of the largest recorded icebergs. The chipping off of the A-68 reduced the total area of the Larsen C Ice Shelf by 12 percent.
The last months and weeks have shown that helost most of its mass, so much so that it simply lost the title of "the largest iceberg in the world." However, its scale remains impressive, especially when looking at satellite imagery taken just 90 km off the coast of South Georgia.
The largest shard of the largest iceberg
British expedition to the RRS James Clark Ross set out to explore marine life on the linecleavage of A-68 in March 2018, but it had to turn back due to thick sea ice. Throughout 2018, the A-68 continued to drift north. In 2018 or 2019, a large chunk (almost 14 km x 8 km) broke off and was named A-68B, and the mother iceberg is now called A-68A.
On February 6, 2020, the A-68A began entering the open water. On April 23, 2020, a piece of about 175 square meters broke away from the iceberg. km, called A-68C.
What is the danger of an iceberg?
When A-68A broke away from the Larsen C Ice Shelf on the Antarctic Peninsula, its surface area was just over 5,800 square kilometers. km. About 70% are still intact.
On November 4, 2020, it was reported that the A-68Aapproached the island of South Georgia. There was a strong possibility that the iceberg could run aground on the shallower continental shelf near the island. Scientists were anxious to see if the A-68a's keel would get stuck on the seabed at any point, securing it in place.
This animation shows the A-68A traveling throughSouth Atlantic Ocean and sea ice concentration from 1 January 2020 to 1 February 2021. The animation uses data from the Advanced Microwave Scanning Radiometer 2 (AMSR2) aboard the JAXA GCOM-W satellite, processed by the University of Bremen, combined with data from the ESA CryoSat mission (DEM 1.2) created by the Center for Polar Observation and Modeling.
If it happened, it would become reala disaster. The iceberg's close proximity to the remote island has raised concerns that it will gain a foothold on the shore and affect the fragile ecosystem that flourishes around the island by scraping the seabed or releasing cold fresh water into the surrounding ocean. South Georgia penguins and seals would be unable to forage, especially if the ice floe were stuck in place for several years.
What happened to the iceberg in 2021?
Recently, however, the iceberg has changed again.
Satellite images showed that in the lastDuring the week, several large cracks were discovered in the iceberg, and since then it has split into several parts. These small icebergs may indicate the end of the A-68A environmental threat to South Georgia.
A-68 February 1. Credit: European Space Agency.
Previously, scientists feared the iceberg would affect the fragile ecosystem that thrives around the island.
In December 2020, the iceberg changed direction,as surface currents of the ocean, controlled by the bathymetry of the seabed, deflected it southeastward from the island, losing a huge chunk of ice in the process.
Iceberg positions A-68 obtained from the Copernicus Sentinel-3 mission. Credit: Contains modified Copernicus Sentinel (2021) data processed by ESA, CC BY-SA 3.0 IGO.
In images taken by a fleet of satellitesCopernicus, footage of the A-68A sailing over the past three years. The latest data from the Copernicus Sentinel-1 mission shows that the iceberg suffered even more damage in 2021, when a new iceberg broke off the A-68A last week. The smaller plate, named by the US National Ice Center A-68G, is about 53 km long and about 18 km at its widest point.
Soon after, a large crack formedin which A-68G escaped, which led to almost immediate spalling of two more icebergs: A-68H (about 20 km long and 9 km wide) and A-68I (about 30 km long). and 5 km wide at its widest point). Antarctic icebergs are named after the Antarctic quadrant in which they were originally seen, then by their ordinal number, and in the event of an iceberg breaking, by letter.
Satellite imagery showed that there was no timethe colossal iceberg A-68A had another amazing experience. Several large cracks were discovered in the iceberg last week and has since split into several pieces. These small icebergs may indicate the end of the A-68A environmental threat to South Georgia. New images taken by the Copernicus Sentinel-1 mission show that the iceberg suffered further damage when another iceberg broke off the A-68A last week. The smaller plate, named by the US National Ice Center A-68G, is about 45 km long and about 18 km at its widest point. Credit: Contains modified Copernicus Sentinel (2021) data processed by ESA, CC BY-SA 3.0 IGO.
The main iceberg A-68A, once the largest inthe world, now has a length of only about 60 km with a maximum width of 22 km. The cumulative group of icebergs appears to be drifting with the A-68H heading north, about 130 km from South Georgia. To date, the main iceberg A-68A appears to be heading south and is located about 225 km from South Georgia. This latest calving event may indicate that the icebergs are likely to leave the island, no longer threatening the island's wildlife.
Copernicus mission optical imagesSentinel-3, revealing the finest details of the A-68A, is only available in a cloudless environment. Sentinel-3, and soon Sentinel-6, altimeter radar measurements can track the trajectory of icebergs, and are also used to calculate estimates of geostrophic ocean currents carried by the A-68A and its children along the way. The Sentinel-1's radar imagery is unaffected by clouds and was instrumental in tracking the destruction of the A-68A.
The map below shows the variousthe position of the iceberg over its three-year journey. The map shows that during the first two years of freedom, the A-68 drifted slowly, restrained by sea ice. But as it moved in relatively open waters, the iceberg's speed increased significantly. The map also includes historical iceberg tracks based on data from several satellites, including ESA's ERS-1 and ERS-2 as part of the Antarctic Iceberg Tracking Database.
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