Experts believe the Delaware-sized A68 iceberg that split from Antarctica’s Larsen C Ice Shelf in July 2017 was likely caused by the thinning of the layer of muddy frozen water that would normally heal cracks.
Glaciologists from the University of California, Irvine and NASA’s JPL have determined that the ice melange, the aforementioned layer, is weakening due to the circulation of ocean water beneath the ice shelves and climate change, a two-pronged attack.
They created three scenarios, looking at 11 cracks in the Larsen C Ice Shelf: if the ice shelf thinned due to melting; if the ice cream blend thinned out; if the ice held and the blend both got thinner.
Experts have determined that the Delaware-sized A68 iceberg that split from Antarctica’s Larsen C Ice Shelf in July 2017 was caused by the thinning of the layer of muddy frozen water that would normally heal cracks.
Once the ice blend thinned, the canyon widened, rising to 367 feet, a rise of 249 feet.
As both the ice shelf and the blend thinned, the rift widened, but to a lesser extent.
And when the ice blend helped heal fissures in the thinning ice shelf, the gap was reduced to 72 feet, from 259 feet.
This layer is weakening due to the circulation of ocean water under the ice shelves and climate change
As the ice blend thinned, the canyon widened to 367 feet, an increase of 249 feet
“The blend is thinner than ice to begin with,” the study’s lead author, NASA JPL researcher Eric Larour, said in a statement. pronunciation.
“If the blend is only 10 or 15 meters thick, it’s similar to water and the ice shelves come loose and start to crack.”
The differences in the three states are caused by the different nature of the substances, Larour said.
In winter, the warmer ocean waters can hit the blend from below and cause the canyon to extend to the entire ice shelf.
“The prevailing theory behind the increase in the calving of large icebergs in the Antarctic Peninsula is hydrofracturing, in which melt pools at the surface allow water to seep down through cracks in the ice shelf, which expand when the water freezes again,” Rignot added. .
“But that theory cannot explain how iceberg A68 could break off the Larsen C Ice Shelf in the dead of the Antarctic winter if no melt pools were present.”
In February, NASA images revealed that the A68 iceberg disintegrated into an “alphabet soup” of individual fragments floating in the ocean north of Antarctica.
Since these ice shelves are believed to prevent glaciers from entering the ocean, any weakening of the ice mix could further accelerate sea rise and further destabilize the ice shelves.
“The thinning of the ice mix that glues together large areas of floating ice shelves is another way that climate change could trigger a rapid retreat of the Antarctic ice shelves,” said one of the study’s co-authors, Eric Rignot, in the paper. a statement.
“With this in mind, we may need to revise our estimates of the timing and magnitude of sea level rise due to the loss of Arctic ice – that is, it could come earlier and with a bigger bang than expected.”
The researchers used NASA’s Ice-sheet and Sea-level System Model, along with observations from NASA’s Operation IceBridge mission and NASA and European satellites to make their observations.
“A lot of people intuitively thought, ‘If you make the ice shelf thinner, you make it much more fragile and it breaks down,’ Larour added.
“We’ve finally started looking for an explanation as to why these ice shelves started to retreat and get into these configurations that became unstable for decades before hydraulic fracturing could act on them,” Rignot said.
“While the thinning ice blend is not the only process that could explain this, it is enough to explain the deterioration we observed.”
The research is published in the Proceedings of the National Academy of Sciences.
WHAT IS THE A-68 ICEBERG AND WHAT CAUSED IT TO BREAK OUT OF ANTARCTICA?
In July 2017, a massive rupture in Antarctica’s Larsen C Ice Shelf caused a trillion-ton iceberg — the third largest ever measured — to break off the icy southern continent.
The huge chunk of ice, called iceberg A-68, measures 5,800 square kilometers (2,240 square miles), making it about the size of Delaware, or four times the area covered by Greater London.
Since the A-68 came loose, it’s remained unclear what will happen to the gargantuan mass, with fears it would break into pieces too small to track on satellite and end up in shipping lanes.
In July 2017, a massive rupture in Antarctica’s Larsen C Ice Shelf caused a trillion-ton iceberg — the third largest ever measured — to break off the icy southern continent. These detailed images were captured by instruments aboard NASA’s Landsat 8 satellite
Experts have found that cracks are still growing on Larsen C, and if they continue to grow, it’s possible the ice shelf could collapse.
If all Larsen C collapses, the ice holding it back could add another 10cm to global sea levels over the years.
Many scientists argue that a calving event was not necessarily due to climate change.
Instead, it may simply reflect an ice shelf’s natural growth and decay cycle.