Experts say the Delaware-sized A68 iceberg separated from the Larsen Ice Shelf in Antarctica July 2017 It may be due to a thin layer of muddy frozen water that would normally heal the rift.
University glacier California, Irvine NASAJPL determined that the aforementioned layer of ice melange was weakened by the circulation of seawater under the ice shelf. Climate change, Two-sided attack.
They created three scenarios, looking at the 11 cracks in the Larsen Ice Shelf. When the ice melange becomes thin. If both the ice shelf and the melange are thin.
Experts have determined that the Delaware-sized A68 iceberg, which separated from the Larsen Ice Shelf in Antarctica in July 2017, was due to a thin layer of muddy frozen water that would normally heal crevices. Did.
As the ice melange thinned, the rift widened and rose from 249 feet to 367 feet.
As both the ice shelves and the melange became thinner, the rift widened, but to a lesser extent.
And when the ice melange helped heal the thinning ice shelf crevice, the gap was cut from 259 feet to 72 feet.
This layer is weakened by seawater circulation under ice shelves and climate change.
As the ice melange thinned, the rift widened from 249 feet to 367 feet.
“In the first place, melange is thinner than ice,” said Eric Larour, a researcher at NASA JPL, the lead author of the study. statement..
“When the melange is only 10 or 15 meters thick, it resembles water and the ice shelf crevices are released and begin to crack.”
The differences between the three states are caused by the differences in the properties of the substances, Larour said.
In winter, warm sea water can hit the melange from below, causing crevices to spread throughout the ice shelf.
“The general theory behind the increase in large-scale iceberg delivery events on the Antarctic Peninsula was hydrofracturalization, which allows water to penetrate through ice shelf cracks that expand when water freezes again.” Lignot added. ..
“But that theory cannot explain how iceberg A68 can break from the Larsen Ice Shelf in the midst of winter in Antarctica, where no molten pool existed.”
In February, NASA’s image shows the A68 iceberg. Collapsed For the “alphabet soup” of individual pieces floating in the northern seas of Antarctica.
Given that these ice shelves are thought to prevent glaciers from entering the ocean, weakening ice shelves can further accelerate sea level rise and make ice shelves more unstable.
In a statement, one of the co-authors of the study, Eric Lignott, said, “The thinning of the ice melange that glues large pieces of floating ice shelves is a rapid retreat of ice shelves in Antarctica due to climate change. Is another way that can cause. ”
“With this in mind, we may need to rethink our estimates of the timing and extent of sea level rise due to the loss of polar ice, which can be faster and more impactful than expected. ”
Researchers used NASA’s ice sheet and sea level system model with NASA’s Operation IceBridge mission and observations from NASA and European satellites.
“Many people intuitively thought,“ Thinning the ice shelf makes it much more fragile and breaks, ”Larour added.
“We have finally begun to seek explanations as to why these ice shelves began to recede and into these configurations that became unstable decades before hydraulic fracturing acted,” Lignot said. Says.
“Thinning ice melange is not the only process that can explain it, but it is enough to explain the degradation we have observed.”
The study is published in Minutes of the National Academy of Sciences..
A-68 What is an ice mountain? What is the cause of your departure from Antarctica?
In July 2017, a large crack in the Larsen Ice Shelf in Antarctica caused the third largest ever recorded 1 trillion tonnes of iceberg to collapse from Antarctica.
The giant iceberg, called Iceberg A-68, measures 5,800 square kilometers (2,240 square miles), about the size of Delaware, and four times the area covered by Greater London.
Since the collapse of the A-68, it was unclear what would happen to the giant mass, and there was concern that it could break into pieces that were too small to be tracked by satellite and flow into the channel.
In July 2017, a large crack in the Larsen Ice Shelf in Antarctica caused the third largest ever recorded 1 trillion tonnes of iceberg to collapse from Antarctica.These detailed images were captured by equipment onboard NASA’s Landsat 8 satellite.
Experts have found that cracks are still growing in Larsen C. If the cracks continue to grow, the ice shelves can collapse.
If all of Larsen C collapses, the ice it holds could add another 4 inches (10 cm) to the world’s sea level over the years.
Many scientists argue that delivery events are not necessarily due to climate change.
Instead, it may simply reflect the cycle of natural growth and collapse of ice shelves.
Antarctica’s ice shelf eroded as layer of slushy frozen water is thinning, study finds Source link Antarctica’s ice shelf eroded as layer of slushy frozen water is thinning, study finds
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