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Home / Science / The fastest-thinned Greenland glacier threw NASA scientists for a round. It actually grows.

The fastest-thinned Greenland glacier threw NASA scientists for a round. It actually grows.



Greenland's fastest-flowing and fastest-declining glacier recently gave scientists a real brain weakness, realizing that instead of shrinking, the glacier is actually getting fatter, they said in a new study.

The glacier – known as Jakobshavn, located on Greenland's west coast, still contributes to sea-level rise, but loses less ice than expected. Instead of diluting and retreating inland, the ice thickens and moves toward the ocean, the researchers found.

The big question: why does this happen? [Images: Greenland’s Gorgeous Glaciers]

A team of scientists from the United States and the Netherlands found after a long mess that the glacier is likely to grow due to colder ocean currents. In 201

6, a current flowing past the Jakobshavn Glacier was cooler than usual, making the water near the glacier the coldest it had been since the mid-1980s.

This cooler current came from the North Atlantic, more than 600 miles (966 kilometers) south of the glacier, according to NASA's Oceans Melting Greenland (OMG) mission and other observations.

The findings completely surprised the scientists. "At first we did not believe it," said research scientist Ala Khazendar, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, in a statement. "We had pretty much assumed that Jakobshavn would just go on like in the last 20 years." But the cold water is not an isolated case. Data from OMG shows that the water has been cold for three consecutive years.

The front of the Icelandic Jakobshavn Glacier, where icebergs cool off.

(Photo: © John Sonntag / NASA / OIB)

It seems that cold water is the result of a climate pattern known as the North Atlantic Oscillation (NAO) that slowly turns the northern Atlantic Ocean between warm and cold Water about every 20 years, the researchers said. The cold phase has just begun and generally cooled the Atlantic, they said. In addition, an additional cooling of the waters around Greenland's southwest coast made for a cool glacier.

However, this crisp change will not last forever. As soon as the NAO climate pattern returns, the Jakobshavn will probably melt faster and become thinner again,

"Jakobshavn gets a temporary break with this climate pattern," said Josh Willis of the Jet Propulsion Laboratory and director of the OMG investigator, said in the statement , "But in the long run, the oceans are warming, and seeing the oceans have such a big impact on the glaciers is bad news for Greenland's ice sheet."

Huge ice loss … then small gain

Scientists have been watching Jakobshavn with concern for decades. After Jakobshavn lost his ice shelf in the early 2000s (an ice shelf forces a glacier to flow more slowly into the ocean as if dirt clogged the drain), he began losing ice at an alarming rate. Between 2003 and 2016, the thickness decreased (from top to bottom) by 152 meters.

  A broader view of the calving front of the Jakobshavn Glacier, as shown by a NASA research aircraft flying above them.

A broader view of the calving front of the Jakobshavn Glacier, as shown by a NASA research aircraft flying above them.

[Image: © John Sonntag / NASA]

But in 2016, the waters of Greenland's southern tip cooled to the west, cooling more than 1.5 degrees Celsius (2.7 degrees Fahrenheit). Meanwhile, the NAO climate pattern has caused the Atlantic Ocean near Greenland to cool by about 0.5 ° C (1 ° C) between 2013 and 2016. By the summer of 2016, these cooler waters reached the glacier, and this is probably the reason why Jakobshavn slowed his speed The ice loss rate in the ocean, the researchers said. [Image: Greenland’s Dramatic Landscape]

Overall, Jakobshavn has grown by about 30 meters (100 feet) between 2016 and 2017, the researchers found. However, as mentioned earlier, the glacier still contributes to the global rise in sea level, as it still loses more ice to the sea than it gains from the accumulation of snow, the researchers said.

The results reveal how high water temperatures are affecting glacier growth, said Tom Wagner, program scientist at NASA's headquarters for the Cryosphere, the frozen part of the Earth.

"The OMG mission deployed new technologies that enabled us to observe a natural experiment, much like we would in a laboratory," where variations in sea temperatures were used to control the flow of a glacier "Wagner, who was not involved in the study, said," Their insights – especially on how fast the ice reacts – will be important for the projection of sea-level rise in both the near and distant future. "

The study was published online in the journal Nature Geoscience on March 25.

Originally published on Live Science .


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