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Cold water is slowing down the fastest Greenland glacier

Studies by NASA
the Jakobshavn Glacier, the fastest flowing and Greenlandic
The fastest thinning glacier of the last 20 years has made an unexpected one
round face. Jakobshavn now flows more slowly, thickening and moving towards him
the ocean instead of retreating further inland. The glacier is added
Global sea level rise – it is losing more and more ice to the ocean than it is
Gain from the accumulation of snow – but slower.

The researchers
conclude that the slowing down of this glacier in the Greenlandic language is well known
Sermeq Kujalleq, because there has been a sea current that brings water to the region
The sea of ​​glacier became much cooler in 201

6. The water temperatures in the
The proximity of the glacier is now colder than since the mid-eighties.

In a study published today in Nature Geoscience
Ala Khazendar from NASA's Jet Propulsion Laboratory in Pasadena, California, and
Colleagues report on the change in behavior of Jakobshavn and trace the source of
the cooler water in the North Atlantic more than 600 miles (966
km) south of the glacier. The research is based on data from the oceans of NASA
Mission Melting Greenland (OMG) and other observations. [NASA'sNASAMeansingGreenland(OMG)missionusesshipsandairplanestomeasurehowoceantemperaturesaffectGreenland'svastexpansesofice

The Jakobshavn Glacier in the central western part of Greenland has contributed to one of the island's biggest contributions to sea-level rise and has decreased in mass faster.

The scientists were so shocked to find that
Khazendar said, "At first we did not believe it, we had a lot
suspected that Jakobshavn would simply continue as in the last 20 years
Years. "However, the OMG mission recorded cold water near Jakobshavn
three years in a row.

The researchers suspect that cold water has been set in motion by a climate pattern
called the North Atlantic Oscillation (NAO), which causes the North Atlantic
Every five to twenty years the ocean changes slowly between warm and cold. The
The climate pattern recently entered a new phase and cooled off the Atlantic
General. This change was accompanied by additional cooling in 2016
Waters along the Greenlandic southwest coast that flowed up the west coast,
finally he reached Jakobshavn.

When the climate pattern changes again, Jakobshavn
will most likely accelerate and thinn out again.

Josh Willis of JPL,
OMG senior investigator stated: "Jakobshavn gets one
temporary break from this environmental pattern. But in the long term, the oceans are
Heat. And seeing the oceans have such a big impact on the glaciers is bad
News for Greenland's Ice Sheet.

Water temperature and weather

Jakobshavn, located on
Greenland's West Coast drains about 7 percent of the island's ice surface. because
of size and importance for sea level rise, NASA scientists and others
Institutions have been watching it for many years.

suggested that the rapid retreat of the glacier began in the early 2000s
Loss of ice shelf of the glacier – a floating extension of the glacier, which slows down
his river. When ice shelves dissolve, glaciers often accelerate in response. Jakobshavn
accelerates every year since the loss of the ice shelf and its front
(where the ice reaches the ocean) has retreated. It has lost so much ice
In 2003 and 2016, its thickness shrank 500 feet from top to bottom (152)

The research team
previous data on sea temperature combined with data from the OMG mission,
which measured the ocean temperature and salinity around the entire island
the last three summers. They found that in 2016 water in Jakobshavns fjord
Cool down to temperatures that have not been seen since the 1980s.

"To trace the source of the cold waters off Jakobshavn was a
Challenge, "said Ian Fenty of JPL, a co-author of the study. There
are enough observations to see the cooling, but not really enough to find out
where it came from. "With an ocean model called Estimating the
Circulation and climate of the ocean (ECCO) to fill in the gaps pursued the team
the cool water upstream (towards the south) to a current, the water around the southern tip of
Greenland and north along the west coast. in the
In 2016, the water in this current cooled more than 2.7 degrees Fahrenheit (1.5

Although the last few
The winters were relatively mild in Greenland itself, they were much colder and cooler
windier than usual over the North Atlantic. The cold weather collapsed
with the switch in NAO climate pattern. Under the influence of this change
The Atlantic Ocean near Greenland cooled by about 0.5 degrees Fahrenheit (1
Degrees Celsius) between 2013 and 2016. These generally cooler conditions set in
the stage for the rapid cooling of the ocean current in the southwest of Greenland
Early 2016. That summer, the cooler waters near Jakobshavn arrived
It was time for Jakobshavn to slow down dramatically.

The team suspects that
Both the widespread cooling in the Atlantic and the dramatic cooling of the waters
which reached the glacier were driven by the displacement of the NAO. If so, that
Cooling is temporary and warm water returns when the NAO turns into a warm water
another phase.

Further implications

The climate of warming
has increased the melting risk for the entire land ice worldwide, but many factors
can accelerate or slow down the speed of ice loss. "For example," said Khazendar,
"The shape of the bed under a glacier is very important, but not
Fate. We have shown that sea temperatures can be just as important.

Tom Wagner, NASA
Program scientist for the cryosphere, who was not involved in the cryosphere
Study, said: "The OMG mission used new technologies
That allowed us to observe a natural experiment, much like we would in one
Laboratory in which fluctuations in sea temperatures to control the
River of a glacier. Their findings – especially about how fast the ice is
responds – is for the projected sea level rise both near and close
Distant future.

The paper on the new research in Nature Geoscience
is titled "Jakobshavn"
20 years of acceleration and thinning interrupted by regional ocean cooling. "
Besides JPL, co-authors at Remote Sensing Solutions in Barnstable,
Massachusetts and the University of Utrecht in the Netherlands.

News Media Contact

Esprit Smith
Jet Propulsion Laboratory, Pasadena, California,
Written by Carol Rasmussen
Earth Science News Team of NASA


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