New Study: Melting ‘glue’ Explains World’s Largest Iceberg Doom
The thinning of an icy “glue” that holds fractured ice together may drive ice shelf collapse in Antarctica, according to a new study.
Ice shelves are massive stretches of ice that build up over many thousands of years, Live Science previously reported. But warming air and rising ocean temperatures have been driving ice shelves to disintegrate. Many of Antarctica’s ice shelves have fractured or collapsed in the past couple of decades, according to the new study, but exactly what’s accelerating the ice loss has been unclear.
To figure this out, a group of glaciologists zoomed in on rifts on Antarctica’s Larsen C Ice Shelf, which calved a Delaware-size iceberg called A68 in July 2017.
The split of A68, an iceberg approximately 2,240 square miles (5,800 square kilometers) in area, reduced the size of Larsen C by 12 percent, Live Science previously reported. Larsen C is the third ice shelf on Antarctica’s western peninsula to undergo massive ice loss in the past two decades.
The prevailing theory was that these splits were happening due to a process known as hydrofracturing, in which pools of melted ice on the surface of ice shelves seep through the cracks and expand once they freeze again, co-author Eric Rignot, a professor of Earth system science at the University of California, Irving, said in a statement. “But that theory fails to explain how iceberg A68 could break from the Larsen C ice shelf in the dead of the Antarctic winter when no melt pools were present.”
Rignot and his colleagues analyzed hundreds of rifts, or fractures, in the Larsen C Ice Shelf, using a model of ice sheets and sea level changes developed by NASA, as well as data from satellites and research aircraft. They zoomed in on 11 cracks and modeled three melting scenarios.
Two out of the three scenarios focused on the role of “melange,” a mix of windblown snow, frozen seawater and ice shelf fragments that exists inside and around rifts and typically works to seal the fractures, according to the statement.
In the first scenario, the glaciologists modeled what would happen if the ice shelf thinned due to melting; in the second, they modeled what would happen if the ice melange thinned; and in the third, they modeled what would happen if both the ice shelf and the melange thinned. Their simulations showed that the thinning of the melange controlled the rate at which the rift opened.
If the ice shelf thinned but the melange remained just as thick, the rift widening slowed down with time. In other words, the melange acted as a “healing” glue, fusing parts of the cracks. If both the ice shelf and the melange thinned, rift widening also slowed but not as much as it did in the first scenario. If the ice shelf remained the same but the melange thinned, as in the third scenario, the average annual rate of the rift widening increased from 249 to 367 feet (76 to 112 meters).
Just like sea ice, melange is vulnerable to the effects of warming oceans and rising air temperatures. “The melange is thinner than ice to begin with,” lead author Eric Larour, NASA Jet Propulsion Laboratory research scientist said in the statement.
Just 32 to 66 feet (10 to 20 m) of melange thinning is enough to reactivate a rift, or start to unzip it and trigger a major calving event, the authors wrote in the study. Reactivating a rift can trigger ice shelves to retreat decades before water ponding would cause hydrofractures on the ice sheet surface, they wrote.
“The thinning of the ice melange that glues together large segments of floating ice shelves is another way climate change can cause rapid retreat of Antarctica’s ice shelves,” Rignot said. “With this in mind, we may need to rethink our estimates about the timing and extent of sea level rise from polar ice loss — i.e., it could come sooner and with a bigger bang than expected.”
The findings were published online Sept. 27 in the journal Proceedings of the National Academy of Sciences.
See more here: livescience.com
Header image: Beck / NASA Operation IceBridge
Bold emphasis added
Editor’s note: I get the impression we are now supposed to believe ‘climate change’ is the ONLY cause of iceberg calving.
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richard
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Antarctica rarely gets above zero degrees and in the vast East Antarctica there has been no melting. Only West Antarctica where there is a concentration of geothermal activity has there been any melting.
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Andy
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Exactly Richard. The peninsula sees much higher temperatures as it’s not far from Patagonia, and it’s on top of multiple active volcanoes which the alarmists constantly ignore.
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Jerry Krause
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Hi Andy,
In your comment are you ignoring the factor known as LATITUDE???
Have a good day, Jerry
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richard
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https://notrickszone.com/2020/01/21/no-alarm-nasa-data-show-antarctica-temperature-trends-undergoing-nothing-unusual/
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Jerry Krause
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Hi Richard and PSI Readers,
It is SO DIFFICULT TO SEE THE OBVIOUS!!!
In articles such as this I have yet to read: PRESSURE MELTS ICE!!!
And the explanation of this easily demonstrated fact is that ice is less dense than liquid water. Hence pressure breaks apart the structure of ice which makes ice less dense than liquid water.
And we know that ice is good thermal insulator and that the interior of the Earth is understood to be very hot. Hence, there is nothing at the base of a thick ice ice sheet over solid ground that is colder than 0C (32F).
But ice sheets which ‘float’ on liquid salt water which has a temperature below the normal melting point of pure water (which ice generally is) only freeze to a thickness of say 3 meters or 9 feet to be conservative in my estimation. For pressure melts the pure ice at the base of the ice sheet. Any floating ice thicker than this is due to the formation of pressure ridges due the expansion of freezing water or the influence of prevailing wind pushing the ice sheet against a mineral shore (coast). The Earth is a very dynamic place.
Have a good day, Jerry
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ЯΞ√ΩLUT↑☼N
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Ice is useless water, except in drinks.
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tom0mason
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Yet another so called science paper that is just a “melange” of theory with ‘would have’, ‘could have’, ‘should’, and imaginary ‘if this, or if that’ and glued together with probably unreal and unverified ‘modeled data’.
Nothing but more pre-fossilized coprolite semantically dressed up to look like real evidence based science.
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Jerry Krause
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Hi TomO,
Long time no read. Wellcome back!!!
Have a good day, Jerry
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