The mysterious song of Antarctica – the cast

A study published last week by the American Geophysical Union documents a chaotic, low-frequency buzz on the Ross Ice Shelf, a French-sized platform that floats off the coast of West Antarctica.

The locations are caused by the wind hitting the snow dunes, and it's kind of a strange song. But, say the researchers, this is also a harbinger of one of the nightmare scenarios of climate change science: the disintegration of the largest ice floe in the Antarctic and the consequent sliding of glaciers into the ocean. .

The song slows down at the beginning of the snow. melt in the upper layers of the pack ice. That's already what happened.

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This was not music as it is thought. Days or months may elapse between each change of tone, composed of notes so low and so slow that they were inaudible to the human ears.

But if you could lie down for 1000 years on Ross's big ice platform and feel every thrill that went through it – if you were the snow itself – then you'd know the chorus.

In January 2016, the song became flat.

Accelerated thousands of times in the frequency range of human hearing, it would appear that the sound of the ice subsided to resemble a tone, a moaning whistle that lasted two weeks among the hottest never recorded on the polar continent.

A song that warned of melting snow.

If the worst fears of climatologists come true – if, during a particularly hot month of this century, the ice floe Ross, 800 km long, collapses like a crumbling border wall , allowing the interior glaciers of the Antarctic The calamity began gradually.

When a small pack ice collapsed across western Antarctica in January 2002, we were blind.

"Scientists Monitoring Daily Satellite Images of Antar The Ctic Peninsula was amazed by almost all of the Larsen B ice shelf that broke and collapsed into a little more than 'a month', writes NASA in its memorial dedicated to this 10,000 year old ice shelf.

"She collapsed between images of a satellite," said Julien Chaput, a geophysicist at Colorado State University The Washington Post . "One picture she was there, another she was not there."

But the pack ice was sick well before his spectacular death. As Chaput explains, the early stages of disintegration are insidious and largely invisible to satellites.

Repeated heat waves melt and refreeze the snow carpet at the top of the pack ice. The snow gets harder and harder

Finally, it becomes so hard that puddles of water form on the surface of the snow and fall to the surface, digging tunnels in the snow to reach the ice. below.

The ice weakens as a decaying boat hull under the onslaught of meltwater. It crackles. The magnitude of the damage is obvious to the satellites towards the end, when the entire plateau – ice, snow and everything – breaks up and dissolves in the ocean in a few days.

It is, to put it mildly, a poor warning system. for the end of the world as we know it.

But as Chaput and his team have shown in an article published last week by the American Geophysical Union, an injured pack ice will sing its troubles long before we show them.

The discovery was "a complete accident," said Chaput. Nobody expected the ice to sing.

Several years ago, another team of researchers installed dozens of seismic stations on the Ross ice floe.

Like many climatologists, they feared that the French-scale floating ice platform never collapsed like Larsen B in 2002, the titanic glaciers that were behind would be free to flee the Antarctic continent, eventually raising the level of the sea ​​of ​​several feet.

"For now, Ross' ice floe seems to be stable," said Chaput. . "But that could change extremely quickly and without notice."

The seismic stations were designed to measure what the Earth's crust and mantle do under the ice – huge earthquake-scale vibrations.

dataset from late 2014 to 2017, he noticed something in the sine waves: a subtle song, vibrating through the upper layers of snow.

"You had these heights, these incredibly defined, persistent and defined tones at each station," he said. "They were changing all the time, depending on the temperature of the air, storms and winds."

Even the movement of a snow dune could alter the frequencies, Chaput said. It was as if all the snow bed had been dug as an old phonograph record, quivering with the rustling of the atmosphere.

The notes hovered around 5 hertz, about four times more than what the human ear can detect. But Chaput could easily speed them up enough to hear – compress rhythms of several days into minutes or seconds

So it's been that he was able to hear what's going on pbaded early 2016, when a particularly hot summer arrived in Antarctica and that the phonograph jumped.

Chaput did not discover the great melting event of January 2016. As Chris Mooney wrote in The Washington Post this disrupted the scientists who had him learned at the time.

The merger of two weeks left nothing as obvious as a lake on the surface of the Ross ice floe. Instead, he turned a Texas-sized, wet and muddy snowpack when the air temperature exceeded the freezing point.

Scientists first detected it by the presence of steam clouds over the sea ice, Mooney wrote, then used microwave satellites. to confirm the damage.

But when in the music of the snow, melting was impossible to miss.

At seismic stations on the other side of the pack ice, the vibrations of the oar subside. Notes stretched in a long drone in some places, like a tornado siren. For Chaput, it sounded like a two-week whine.

"It does not seem very happy to me," he said.

Ice music, he explains, is made by the wind that pbades over Snow Dunes and sends of vibrations through billions of ice crystals compressed in the snow bed – called a "walnut".

"The snow contains 80% air, with flaky links between the crystals," said Chaput "As they weaken, the speed of movement of a wave decreases, so the tones go down." It decreases and becomes quieter. "

All this could just mean that Chaput found a depressing soundtrack for melting an ice floe.But as described in his article, the music also has potential as a & dquo; Measuring tool – something that looks like a sonogram for the health of snow and ice in times of future warming, which he expects of many others.

That does not mean that we [19659002] Ross' former pack ice crash came back shortly after the end of the heat wave at the end of January, when snow and crystals were overflowing with ties.

But on many listening stations, the sound is no longer the same. The warble now has something that looks like a grater.

"You can see the physical impact," Chaput said. "When it gets cold again, the nicotine will partially heal and rebound in some ways, but not completely."

He does not know if the Ross Ice Shelf will regain its original structure and voice, or if it has been permanently damaged, as the Larsen B ice shelf was to be long before to break.

For the moment, even imperfectly, he continues to sing.