NASA scientists follow the melting ice of Greenland, and the results are not good



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ONBOARD A NASA RESEARCH PLANE ON GREENLAND – The waving ice fields 500 feet below NASA's plane leave room for blue-green water dotted with irregular pieces of bleached ice, sometimes of the size of battleships, some up to 15 buildings of history.

Like almost every other glacier in Greenland, the Kangerlussuaq Massif is melting. In fact, the frozen giant island has experienced one of its biggest fonts recorded this year. NASA scientist Josh Willis is now studying this phenomenon closely, hoping to understand precisely how global warming is eating away at Greenland ice.

Specifically, he wants to know if the melting is caused more by hot air or by hot seawater. The answer could be crucial for the future of the Earth.

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The water brings more heat to something frozen faster than air, as anyone who has already thawed a steak under the tap knows.

If Willis' theory that much of the damage is caused by water turns out to be correct, he says, "Greenland is much more likely to melt faster than we thought." That means that the sea is rising faster and coastal communities are flooded. more.

Greenland contains enough ice to raise the level of the world's seas if it were to melt. In a single day this month, it lost a record of 13.7 billion tonnes according to one estimate.

"It's a bit scary," Willis said, looking down at an area filled with water rather than ice. "We are watching the pack ice disappear before us."

Climate change is eating away Greenland's glaciers in two ways. The most obvious way is to use the warm air above, which was brutal this summer, with a European heat wave in July running like a hair dryer on the ice. The other way is to use warm, salty water, partly from the Gulf Stream of North America, nibbling the coastal glaciers from below.

When the ice scientist from the University of Georgia, Tom Mote, who was not part of this project, started studying Greenland glaciers in the early 90s, the researchers really did not think that the watershed in the early 90s was a good thing. Water was an important factor.

Willis' project – called Oceans Melting Greenland, or OMG – shows that this is the case. Now the question is how much and how fast.

What Willis measures is water more than 660 feet from the surface, hotter and saltier than objects in contact with the air. It is this deep water that does the biggest damage.

To measure this, NASA spent five years cruising the island with a 77-year-old DC-3 built for the Second World War. Willis, project manager Ian McCubbin and mechanic Rich Gill lay long cylindrical probes through a special tube in the floor of the aircraft, watching the sensors parachute and then diving into the icy water.

McCubbin then waits for a tone on her computer telling her that the probe is under water and that she is measuring temperature and salinity. When all five flight probes start reporting – with a sound, McCubbin calls "AOL fax or modem" – from top to top, with Willis.

Meanwhile, pilots Andy Ferguson and Don Watrous lead the plane towards the blue-green spots, searching for the next target and pointing out the impressive giant icebergs and the signs of retreating glaciers on the radio.

As the data was retransmitted by a $ 2,000 probe located at the bottom of the water near Kangerlussuaq in eastern Greenland, it seems first that the temperature has not changed much in the past year or so. two, which could be good news. But this is only one data point. Every year for the past four years, NASA has been interested in the whole of Greenland, and the numbers as a whole are not so comforting.

If water plays a much larger role than scientists thought, it could mean that the seas will rise faster and higher than expected. That's because 90% of the thermal energy produced by climate change is routed to the oceans, Willis said. Hot water provides "better value for money" than air when it comes to melting ice, Willis said.

The Jakobshavn Glacier, the rapidly shrinking glacier on the more densely populated West Coast of Greenland, illustrates how essential sea water is to melting. In recent years, it has suddenly started to grow a bit, probably because of a cooling of the waters as a result of a temporary change in the time and configuration of the water currents, said Willis.

In general, the oceans heat up much more slowly than the air, but they stay warmer longer. Water weakens glaciers and causes icebergs to thaw. These icebergs eventually melt, which adds to the sea.

"Some are as big as a city," Willis said.

A 2019 study by Danish climatologist Ruth Mottram examined long-term data on 28 glaciers in Greenland. Almost all are melting, with only one or two that could be considered fairly stable.

"A receding glacier looks like carelessness, but backing up is a sign that something is happening," Mottram told the Associated Press.

A study conducted in 2017 concluded that coastal glaciers and ice caps – what Willis is currently studying – reached a "critical threshold" for ice loss in 1997 and have since deteriorated rapidly. A NASA satellite has revealed that the Greenland ice cap was losing about 255 billion metric tons a year between 2003 and 2016, with the loss rate generally worsening.

It will take centuries for all of Greenland's ice cap to melt, but the key question is how fast. If hot water plays a more important role than scientists suspect, by 2100, Greenland alone could cause a rise in sea level of 3 to 4 feet (more than 10%). 39, one meter), said Willis.

Other scientists, such as Ted Scambos of the University of Colorado, claim that Greenland's contribution to sea level rise by 2100 would probably be closer to 30 cm (1 foot).

It's a big spread.

"I tend to go to the highest number, but hopefully a lower number," said Christopher Shuman, a Baltimore County glaciologist from the University of Maryland, whose family owns the property. along the coast.

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