The giant iceberg called A-68 that broke off in July 2017 released 152 billion freshwater, from the Larsen-C Ice Shelf of Antarctica. This was reported by the European Space Agency. Thanks to five different satellite missions of which many of the ESA, a team of scientists – from the Center for Polar Observation and Modeling in the United Kingdom and the British Antarctic Survey – have in fact been able to monitor the path of the iceberg – one of the largest ever produced in Antarctica – and follow the its path driven by winds and ocean currents. The researchers were thus able to follow the evolution of the ice giant which gradually divided into several ‘smaller’ bergs. Following him with the eye of the satellites, Scientists were able to detect the gigantic amount of fresh water released during the journey that brought the iceberg off the coast of the South Georgia islet. Once averted that the iceberg ran aground in front of South Georgia, now the alarm of the scholars is that in any case the immense quantity of fresh water released may have interfered with the local marine ecosystem.
The satellites followed the iceberg’s long ‘journey’ into the Southern Ocean and, three and a half years later, saw the main part of the ice giant – renamed A-68A – detach from the A-68 and drift away from the A-68. worrying near South Georgia. Initially what worried scientists was the risk that the berg would run aground in the shallow waters offshore, which “would not only have damaged the ecosystem of the seabed, but it would also have made it difficult for the island’s wildlife, such as penguins, to reach the sea to feed. “. Using satellite measurements, the scientists tracked how the A-68A shrank in size towards the end of its journey, which “thankfully kept it from getting stuck.” However, “the downside is that the berg released a colossal amount of fresh water equal to 152 billion tons near the island, potentially with a profound effect on the island’s marine life “ warn by the European Space Agency. When it broke away, the giant A-68 iceberg had a surface area of more than twice that of Luxembourg, “one of the largest icebergs ever recorded”, according to the ESA.
Almost immediately after forming, the iceberg lost a piece of ice and, according to the technical-scientific rules that identify icebergs, the two ice ‘stumps’, the larger berg was renamed A-68A while the smaller ‘stub’ became A-68B. In April 2020, the A-68A lost another piece subsequently called the A-68C. Esa recalls that “Antarctic icebergs are named after the Antarctic quadrant in which they were originally sighted, so a sequential number is used and, if the iceberg breaks, a sequential letter is added to the original number with which the iceberg as soon as he was formed he was ‘baptized’ “. Overall, the A-68A iceberg has thinned by 67 meters from its initial thickness of 235 meters, with the rate of dissolution soaring while the berg moved into the Scottish Sea, around South Georgia.
An article published in Remote Sensing of Environment described how researchers from the Center for Polar Observation and Modeling in the UK and the British Antarctic Survey combined measurements from different satellites to track how the A-68A has changed in the area. and in thickness during its life cycle. The A-68A’s journey was tracked using observations from five different satellite missions. ESA explains that to track how the A-68A area has changed, scientists used optical images from the Copernicus Sentinel-3 mission and the Modis instrument on the Us Terra mission, along with radar data from the Copernicus Sentinel-1 mission. “While Sentinel-1 radar images offer all-weather capability and higher spatial resolution, Modis and Sentinel-3 optical images have higher temporal resolution but cannot be used during polar night and cloudy days.” clarifies the European Space Agency. Also, to measure changes in the free edge of the iceberg, or the height of the ice above the sea surface, data from the ESA CryoSat mission and the US IceSat-2 mission were used. “Knowing the free edge of the ice means that it is possible to calculate the thickness of the entire iceberg,” explains ESA. All of these measurements together allowed the scientists to calculate how the volume of the iceberg changed and thus how much fresh water it released.
Tommaso Parrinello, ESA’s CryoSat Mission Manager, said: “Our ability to study every movement of the iceberg in such detail is thanks to advances in satellite techniques and the use of a variety of measurements. Imaging satellites record the shape of the iceberg and altitude mission data such as CryoSat they add another important dimension as they measure the height of surfaces, which is essential for calculating volume changes. “ The new study reveals that the A-68A only briefly collided with the seabed and broke shortly thereafter, making it less risky. When it reached the shallow waters around South Georgia, the keel of the iceberg had shrunk to 141 meters below the ocean surface, shallow enough to avoid the sea floor which is about 150 meters deep. If the keel of an iceberg is too deep it can get stuck on the sea floor and this can be disruptive in many ways: scuff marks can destroy fauna and the berg itself can block ocean currents and predator foraging routes. clarify from the ESA.
However, a side effect of the disbandment was the release of a colossal amount – 152 billion tons – of fresh water near the island, an ‘interference’ that scholars believe “could have a profound impact on the island’s marine habitat.” When icebergs detach from ice shelves, they drift with ocean currents and wind, releasing cool, cold meltwater and nutrients as they melt. This process affects the local ocean circulation and favors organic production around the iceberg. Anne Braakmann-Folgmann, PhD student at the Center for Polar Observation and Modeling and lead author of the study, finally explains that “This is a huge amount of meltwater and the next thing we want to understand is whether it has had a positive or negative impact on the ecosystem. around South Georgia “and” since the A-68A has taken a common route through the Drake Passage, we hope so. ”