A Greenland glacier has started to grow again, but that does not mean what you think

The fastest-shrinking Greenland glacier has taken an unexpected turn.

Although it has been melting for 20 years, the Jakobshavn Glacier, in West Greenland, famous for producing the iceberg that sank the Titanic, has begun to grow again.

Since the 1980s, the waters have warmed around Baffin Bay, where the glacier meets the sea. However, recent data from NASA reveal that in 2016, the ocean current has become colder.

As a result, the Jakobshavn glacier ice thickens, flows more slowly and stretches out to the ocean.

The waters around the mouth of the glacier – also known as Sermeq Kujalleq in Greenlandic – are now the coolest since the 1980s.

"At first, we did not believe it," said glaciologist Ala Khazendar of NASA's Jet Propulsion Laboratory. "We thought pretty much that Jakobshavn would continue as if nothing had happened in the last 20 years."

jakobshavn retreatThe Jakobshavn Calving Front from 1851 to 2006. (NASA Earth Observatory)

But over the past three years, this cold water has continued to arrive, according to data from NASA's Oceans Melting Greenland (OMG) mission and other sources.

In a new document, Khazendar and his team identified the cause – and, yes, it's only temporary.

The team charted the current with the help of observations and an ocean modeling system developed by NASA to fill the gaps in the data.

Cooling started in the North Atlantic Ocean, 966 kilometers south of the glacier, under the influence of a climate pattern called the North Atlantic Oscillation (NAO): every five to 20 years, atmospheric pressure at the the sea fluctuates with either warming or cooling, which is then dragged northward by ocean currents on the southwest coast of Greenland.

In 2016, the water in this current was cooler by 1.5 degrees Celsius, cooling the Atlantic around Greenland by about 1 degree Celsius; this led to Jakobshavn's mouth, allowing the ice to thicken.

This seems to be a tiny increase for such a big effect, is not it? Even the researchers were surprised.

"We did not think that the ocean could be so important," said Josh Willis, OMG Principal Investigator, at the Jet Propulsion Laboratory. National Geographic.

But, inevitably, the pendulum will go back and the glacier will shrink again.

Meanwhile, the rest of Greenland's icecap is still declining; and, even if this slight growth were to continue, it would not be able to compensate for the intense losses suffered up to now.

Some of the oldest and thickest ice in the Arctic erupted last year. This is the first time it has been this way. And it happened twice.

More than half of the permanent ice in the Arctic has melted; and melting ice and snow have revealed arctic landscapes hidden for 40,000 years.

In fact, according to a UN report last year, we have passed the point of no return. The damage is done; the Arctic is warming up and we can not do anything to stop it.

Jakobshavn has been melting since the early 2000s, when it lost its ice cream. This floating ice platform slows the flow of a glacier; so, when Jakobshavn broke up, his flow increased.

Since then, its melting has accelerated and the glacier front has withdrawn from the ocean. Between 2013 and 2016, he lost 152 meters (500 feet) of thickness.

Jakobshavn has not even nearly replaced this volume, and that will probably not be the case. It is unlikely that the cooling of the NAO will exceed the warming.

"Jakobshavn is temporarily out of this climate, but in the long term, the oceans are warming up, and seeing the oceans have such a huge impact on glaciers is bad news for the Greenland ice sheets," Willis said.

This research demonstrates that the glacial recession is not a one-way trend, but does not show a reversal of climate change. This indicates that the effects are a little more complex than we thought, but that eventually this bird flew away.

"This cooling will pass," said Khazendar National Geographic. "When that happens, the glacier will retreat even faster than before."

The search was published in Nature Geoscience.

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