Nevertheless, the ecosystem and wildlife around South Georgia will certainly have felt the impact of the colossal iceberg's visit. By the time it reached the shallow waters around South Georgia, the iceberg's keel had reduced to 141 metres below the ocean surface, shallow enough to avoid the seabed which is around 150 metres deep. ![]() However, this new study reveals that it collided only briefly with the sea floor and broke apart shortly afterwards, making it less of a risk in terms of blockage. All of these potential outcomes were feared when A68A approached South Georgia. This can be disruptive in several different ways the scour marks can destroy fauna, and the berg itself can block ocean currents and predator foraging routes. If an iceberg's keel is too deep it can get stuck on the sea floor. Frequent measurements allowed us to follow every move and break-up of the berg as it moved slowly northwards through iceberg alley and into the Scotia Sea where it then gained speed and approached the island of South Georgia very closely." "A68 was an absolutely fascinating iceberg to track all the way from its creation to its end. ![]() Laura Gerrish, GIS and mapping specialist at BAS and co-author of the study said: Altogether, the iceberg thinned by 67 metres from its initial 235 m thickness, with the rate of melting rising sharply as the berg drifted in the Scotia Sea around South Georgia. However, once it began its northwards journey across Drake Passage it travelled through increasingly warm waters and began to melt. However, a side effect of the melting was the release of a colossal 152 billion tonnes of fresh water in close proximity to the island - a disturbance that could have a profound impact on the island's marine habitat.įor the first two years of its life, A68A stayed close to Antarctica in the cold waters of the Weddell Sea and experienced little in the way of melting. The authors show that the berg had melted enough as it drifted to avoid damaging the sea floor around South Georgia by running aground. Researchers from the Centre for Polar Observation and Modelling (CPOM) and British Antarctic Survey (BAS) used satellite measurements to chart the A68A iceberg's area and thickness change throughout its life cycle. Around Christmas 2020, the berg received widespread attention as it drifted worryingly close to South Georgia, raising concerns it could harm the island's fragile ecosystem. At 5719 square kilometres in extent - quarter the size of Wales -, it was the biggest iceberg on Earth when it formed and the sixth largest on record. The US space agency says it is unclear whether the small overall increase in sea ice expanse is a sign of meaningful change because ice areas vary considerably from year to year and from sector to sector.Ĭonsidered individually, only the Ross sea sector had a significant positive trend, while sea ice extent has actually decreased in the Bellingshausen and Amundsen seas.In July 2017, the A68A iceberg snapped off the Larsen-C Ice Shelf on the Antarctic Peninsula and began its epic 3.5 year, 4000 km journey across the Southern Ocean. Since the start of satellite records in 1979, total Antarctic sea ice has increased by about 1% a decade, according to Nasa. However, before melting it could present a danger to ships, Young said. Scientists believe the iceberg off Macquarie will break up and melt rapidly as it meanders northwards. The first was about 190 miles long and 23 miles wide. Several huge icebergs broke off from Antarctica's Ross ice shelf and the Ronne ice shelf in 2000 and are now drifting away from Antarctica. We know there are also a few more icebergs 100km-200km to the west of the island." "Throughout the year several icebergs have been drifting slowly northwards with the ocean current towards Macquarie Island. ![]() Neil Young, an Australian Antarctic division glaciologist, said: "The iceberg is likely to be part of one of the big ones that calved from the Ross ice shelf nearly a decade ago. Scientists have said it is rare for icebergs to be seen so far north. Estimated to be about 50m high – from the waterline – and 500m long, the iceberg is now about five miles (8km) off the north-west of Macquarie island, halfway between New Zealand and Antarctica south-west corner of the Pacific Ocean.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |