Science & Technology

Unprecedented Look at Ice Stream Formation on Remote Russian Glacier [Video]

Landsat 8 false-color composite of Vavilov Ice Cap on June 24, 2018. Authors of a brand new examine suspect the pictures present the primary commentary of a transition from a glacial surge to a longer-lasting stream referred to as an ice stream. Credit score: AGU/Geophysical Analysis Letters/Whyjay Zheng.

Scientists have captured the start of a high-speed ice characteristic for the primary time on high of a Russian glacier.

In a distant archipelago of the Russian Arctic, Vavilov Ice Cap had been shifting at a glacial tempo for many years. Then, in 2013, it out of the blue began spewing ice into the ocean, flowing in what scientists name a glacial surge. However a brand new examine suggests this surge has now change into one thing fully totally different.

The authors of the new study revealed within the AGU journal Geophysical Analysis Letters have documented what they consider is the primary commentary of a transition from a glacial surge to a longer-lasting stream referred to as an ice stream.

Ice streams and glacial surges have been believed to be separate phenomena pushed by totally different mechanisms. But when the authors of the brand new examine are appropriate, glacial surges may as an alternative be an early stage of an ice stream. If surging ice can kind an ice stream on a glacier like Vavilov, then different ice caps may additionally expertise comparable fast ice loss, stated Whyjay Zheng, a Ph.D. candidate at Cornell College and the lead creator of the brand new examine.

“If that’s true, we most likely must revise our predictions for the influence of world sea stage rise sooner or later,” he stated.

From the time the surge at Vavilov started in 2013 till the spring of 2019, the ice cap misplaced 9.5 billion tons of ice, or 11 % of the ice mass of all the glacier basin.

Ice streams have been documented earlier than in Greenland and Antarctica, the place the ice sheets are typically bigger and their stream much less constrained by bedrock options. To see an ice stream in a smaller ice cap like Vavilov could be uncommon and maybe unprecedented, in keeping with the examine’s authors. And so far as the researchers know, nobody has noticed one being shaped.

“For those who look at the satellite tv for pc photos, it looks like all the west wing of the ice cap is simply dumping into the ocean,” Zheng stated. “Nobody has ever seen this earlier than.”

Zheng and different researchers at Cornell had been monitoring satellite tv for pc photos of this space since 2015, documenting the elevation change of the ice in a separate examine. After the preliminary glacial surge, Zheng stated, they determined to maintain a watch on how the ice cap modified over time.

When the researchers analyzed the satellite tv for pc photos to see how the surge had progressed, they discovered that Vavilov was nonetheless collapsing. However by 2017, the way in which it was collapsing had modified.

Landsat 8 false-color composites of Vavilov Ice Cap on July 1, 2013 (above) and June 24, 2018 (high of web page). Shear margins started to kind at the perimeters of the ice stream in 2016, showing as darkish, horizontal stripes within the picture on the precise.
Credit score: AGU/Geophysical Analysis Letters/Whyjay Zheng.

From 2013 to 2016, Vavilov Ice Cap flowed in what gave the impression to be a typical glacial surge. Ice at the glacier’s edge the place it met the Arctic Sea bulged outward in a large fan form, surging ahead for about 10 kilometers at a most velocity of 26 meters per day.

Then, in 2017, the ice fan stopped advancing. As an alternative, darkish stripes appeared on the satellite tv for pc photos, indicating crevasses that had shaped at the perimeters of the nonetheless fast-flowing ice.

Glacial surges transport huge quantities of ice in a brief period of time, usually a couple of months to a number of years. Then again, ice streams can preserve a relentless, fast stream for many years to centuries.

An ice stream is characterised by its long-lasting stream, but in addition by options referred to as shear margins that kind at the perimeters of the flowing ice. When the examine’s authors noticed these darkish stripes, Zheng stated, “We thought, wow, that is completely much like an ice stream.”

This was the primary clue that what the researchers have been seeing was an ice stream forming from the preliminary glacial surge. To search out additional proof, the examine’s authors used the satellite tv for pc knowledge to calculate the elevation change and velocity of the glacier over time.

The authors discovered that after the 2017 transition interval, the form of the glacier’s stream resembled an ice stream, indicated by its light slope and slim width. The situation of the fastest-flowing ice additionally modified after 2017, with the utmost velocity shifting from the higher a part of the glacier (typical of a surge) to the top level, or terminus, of the glacier (typical of a stream).

Not a lot is thought concerning the formation and conduct of ice streams. Due to their distant places, long-term observations of ice streams are scarce, in keeping with the authors of the brand new examine. Whereas we all know that ice streams are inclined to final for a very long time—many years to lots of of years—nobody is aware of the common lifespan of those glacier options.

Denis Felikson, a cryospheric scientist at NASA Goddard House Flight Heart who was not concerned within the analysis, stated will probably be fascinating to observe Vavilov for the subsequent a number of years to see whether or not the ice stream lasts lengthy sufficient to categorise as an ice stream. However, he stated, he believes the brand new examine exhibits sturdy proof for a transition from a glacial surge to an ice stream.

“It’s actually thrilling that they discovered this and are documenting it, as a result of now we have very restricted understanding of how these glacier behaviors work,” Felikson stated. “There are some theories on how ice streams kind, however to truly observe the opportunity of that occuring is exclusive and thrilling.”

Reference: “The Attainable Transition From Glacial Surge to Ice Stream on Vavilov Ice Cap” by Whyjay Zheng, Matthew E. Pritchard, Michael J. Willis and Leigh A. Stearns, 21 November 2019, Geophysical Analysis Letters.
DOI: 10.1029/2019GL084948

PopCash.net
Back to top button