Latest news with #BruntIceShelf
Gizmodo
2 days ago
- Science
- Gizmodo
Scientists Uncover Surprising Link Between Tides and Earth's Biggest Icebergs
In 2021, researchers in Antarctica noticed giant cracks developing on the Brunt Ice Shelf, an enormous stretch of ice on the continent's northwestern corner. Two years later, the fracture grew so large that a gigantic iceberg almost twice the size of New York City broke free in a process called calving, sending scientists scrambling to investigate the icy chunk, which they named iceberg A-81. A team of researchers affiliated with the British Antarctic Survey sought to understand the forces driving this 'crack behavior' in the huge ice shelf. By devising a mathematical model to account for natural forces affecting ice shelves, the researchers found that iceberg A-81—and most other icebergs, for that matter—likely snapped off from tidal forces buffeting the ice shelves in spring, when the currents are strongest. The paper, published in Nature Communications on July 24, supports common-sense assumptions about environmental forces playing a major role in driving calving events, but the proposed model could also improve prediction models for calving events, a historically challenging task. 'Understanding what controls the timing of these events is crucial, because calving not only affects the shape and melt rate of ice shelves but also their long-term stability,' said study lead author Oliver Marsh, in a statement. 'It's incredibly exciting to uncover a link between something as predictable as the tides and the dramatic, sudden process of iceberg calving.' For the paper, Marsh and his colleagues first devised a mathematical model to calculate the threshold for crack behavior in the ice shelves using ocean tides or wind patterns as potential stressors. Next, they tested their predictions against GPS and radar data, paying close attention to the subtle movements and stresses that appeared within the ice shelf over time. They noticed that the fractures tended to grow most in spring, which happens to be when tides are strongest. The model, however, is a simplified interpretation of real-life dynamics in Antarctica, the study authors admitted, and it better explains smaller, gradual changes in crack behavior. This means that more dramatic events—like extreme temperatures from climate change—will cause even bigger rifts in the ice. 'Tides and wind are key to the timing of small individual rift growth events here,' the authors wrote in the paper, 'but it is notable that an iceberg collision in 2021 caused more substantial rift growth in a single event than throughout 2020.' Nevertheless, the study marks a crucial step in modeling the role of environmental drivers in calving events, which the authors argue will subsequently inform our models of iceberg calving under such extreme atmospheric or ocean conditions. Large icebergs also influence ocean circulation and local ecosystems, so the new model could serve as a useful tool for structuring research projects in Antarctica, Marsh explained. 'Icebergs like A-81 can be thousands of square kilometers in size and account for roughly half of all ice lost from Antarctica each year,' Marsh said. 'This kind of insight brings us closer to forecasting major ice loss events and their impact on sea level with far greater precision.'
News.com.au
5 days ago
- Science
- News.com.au
Tides could help predict when huge icebergs break loose: study
Ocean tides can trigger city-sized icebergs to break off from Antarctic ice shelves, scientists said on Thursday, offering a potential way to predict these dramatic events in the future. It is not normally possible to forecast when icebergs break free, or calve, although the timing is important because these behemoths change the shape of ice sheets and affect global sea levels. Yet when a chunk of ice the size of Greater London suddenly broke off the Brunt Ice Shelf in 2023 and started drifting away, glaciologist Oliver Marsh was not surprised. Marsh told AFP he had predicted that a huge iceberg breaking off was "imminent within the next weeks to months". The British Antarctic Survey researcher had spent years studying the huge crack that would create the 550-square-kilometre (210-square-mile) iceberg named A81. As Marsh had anticipated, the calving occurred at the peak of spring tide, when there is the biggest difference between the ocean's high and low tide. New research led by Marsh, published in the journal Nature Communications on Thursday, used modelling to show that the calving was triggered by the tide, along with high winds and stress on the ice. After A81 broke off, Marsh visited the ice shelf to see how open water had replaced what had previously been "ice as far as you could see". "It was sad to see it go, in a way," he said. A81 is currently drifting up the eastern side of the Antarctica Peninsula towards the Weddell Sea. It remains to be seen whether it will come close to South Georgia island, which is an important breeding ground for penguins, seals and other animals. - 'Out of balance' - The world's biggest iceberg, A23a, ran aground not too far from South Georgia earlier this year but is not thought to pose a threat to wildlife. Now that A23a is exposed to the waves of the Southern Ocean, its "days are numbered", Marsh said. He emphasised that iceberg calving is a natural process which balances out the massive amount of snow that falls on Antarctica every year. However, "now we're out of balance", Marsh added. Antarctica loses ice in two ways -- icebergs calving and ice sheets melting. And ice sheets are melting at a rapidly increasing rate as oceans warm due to human-driven climate change, scientists have warned. "We don't know whether calving rates have gone up" because they happen relatively infrequently, Marsh said. A81 was the second of three mammoth icebergs that have broken free of the Brunt Ice Shelf since 2021. "We are expecting a very large calving event at some point from this area" in the future, Marsh said. But he could not give a timeframe. dl/gil
France 24
5 days ago
- Science
- France 24
Tides could help predict when huge icebergs break loose: study
It is not normally possible to forecast when icebergs break free, or calve, although the timing is important because these behemoths change the shape of ice sheets and affect global sea levels. Yet when a chunk of ice the size of Greater London suddenly broke off the Brunt Ice Shelf in 2023 and started drifting away, glaciologist Oliver Marsh was not surprised. Marsh told AFP he had predicted that a huge iceberg breaking off was "imminent within the next weeks to months". The British Antarctic Survey researcher had spent years studying the huge crack that would create the 550-square-kilometre (210-square-mile) iceberg named A81. As Marsh had anticipated, the calving occurred at the peak of spring tide, when there is the biggest difference between the ocean's high and low tide. New research led by Marsh, published in the journal Nature Communications on Thursday, used modelling to show that the calving was triggered by the tide, along with high winds and stress on the ice. After A81 broke off, Marsh visited the ice shelf to see how open water had replaced what had previously been "ice as far as you could see". "It was sad to see it go, in a way," he said. A81 is currently drifting up the eastern side of the Antarctica Peninsula towards the Weddell Sea. It remains to be seen whether it will come close to South Georgia island, which is an important breeding ground for penguins, seals and other animals. 'Out of balance' The world's biggest iceberg, A23a, ran aground not too far from South Georgia earlier this year but is not thought to pose a threat to wildlife. Now that A23a is exposed to the waves of the Southern Ocean, its "days are numbered", Marsh said. He emphasised that iceberg calving is a natural process which balances out the massive amount of snow that falls on Antarctica every year. However, "now we're out of balance", Marsh added. Antarctica loses ice in two ways -- icebergs calving and ice sheets melting. And ice sheets are melting at a rapidly increasing rate as oceans warm due to human-driven climate change, scientists have warned. "We don't know whether calving rates have gone up" because they happen relatively infrequently, Marsh said. A81 was the second of three mammoth icebergs that have broken free of the Brunt Ice Shelf since 2021. "We are expecting a very large calving event at some point from this area" in the future, Marsh said. But he could not give a timeframe. © 2025 AFP
