Anomalous warming played a role in 2002 Antarctic ice shelf retreat: Study

NEW DELHI: A new study finds that the unique atmospheric and oceanic warming He played a role in its collapse in 2002 Antarctic Larsen B ice rinkWhen the large ice field on Rhode Island was sharply torn from it.
The study found that widespread flow acceleration and frequent calving of small icebergs could be similar warning signs in the future. the ice rink recedes In the Antarctic, say the scientists of the Pennsylvania State University (Penn State), who led the study.
The results of the study were published in the journal Earth and Planetary Letters.
Ice shelves are floating tongues of ice that are attached to land but extend and float in ocean water.
They act as buttresses that hold back glaciers on land that flow into the ocean.
Therefore, it is important to understand how they react to continuous warming predicting sea level rise right, say scientists.
The five calving pulses observed between 1998 and 2002 coincided with climatic fluctuations caused by La Niña and the Southern Annular Regime, characterized by strong westerly winds. Southern Hemisphere approach Antarctica“, the research says.
Warmer ocean waters can cut channels beneath the ice sheet, further weakening vulnerable parts of the ice shelf known as shear edges. Scientists distinguish these edges from flowing ice from stagnant ice or rock, and the areas often contain cracks and soft ice.
“The results show that warm climate fluctuations control the occurrence of calving, and the degree and rate of calving depends on the geometry and mechanical conditions of the ice shelf, in particular the strength of the weakest shear edge,” said Shujie Wang, assistant professor. of Penn State and lead author of the study.
Scientists believe that shear-edge failure in the northern part of the ice sheet may have triggered the calving pulses, and as the ice retreated, it moved away from the rocky islands that were the buttresses holding the sheet in place.
“When you pin a sheet of paper to the wall, the pins prevent the paper from falling to the floor,” Wang said. “It’s the same with ice flow – these rocky islands act as ‘fulcrums’ that anchor the ice and slow its movement towards the sea.”
The distribution of these anchor points may help determine the vulnerability of the ice sheet, as a weak shear margin with limited anchorages played a dominant role in destabilizing the Larsen B Ice Shelf and initiating a chain of small iceberg calving, the scientists reported.
“The collapse of the Larsen B ice shelf is generally considered an independent event,” Wang said.
“Our work shows that this was the last stage of calving, which began in 1998 and was driven by atmospheric and oceanic warming anomalies that weakened the ice shelf structure over time,” Wang said.
Although scientists have long known that warming air and ocean temperatures melt and weaken ice shelves from both the surface and subsurface layers, the exact processes that lead to the collapse are not well understood.
“Ice sheet loss from global warming is the fastest-growing route to sea level rise for Antarctica, but it’s difficult to predict in part because we have so few observations,” said Richard Alley, co-author of the study at Penn. State.
“The Larsen B Ice Shelf did not retain much land ice, so its loss was not particularly significant for sea level, but it provides an excellent laboratory for early warning signs and learning about ice sheet loss processes.
“The new insights gained here should help major efforts to design how warming interacts with ice shelves to control future contributions to sea-level rise,” Alli said.
Scientists collected data on the ice shelf dating back to the 1960s and analyzed changes over time using satellite observations, modeling experiments and climate reanalysis data, the study said.
Before the 2002 collapse, the ice shelf experienced a transition from regular large calving events—when chunks of ice break off into the ocean—to more frequent, smaller calvings and a faster, more widespread flow of ice toward the sea.
“Typically, large chunks of ice break off, regrow and break off again over decades,” Wang said.
“There were a lot of small calving events and the ice didn’t grow back. And when the rocky islands that supported the ice shelf retreated, it didn’t stop the flow,” Wang said.
“These small areas are important to the entire region,” Wang said.
“If you look at the ice shelf as a complex system, local areas can have a dominant effect on the entire ice shelf. These basics are important because if we don’t understand the basics, we can’t make the most accurate predictions for the future,” Wang said.

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