In ancient Greek mythology, the Sirens were haunting creatures that could lure sailors with eerie songs and music, often causing the seafarers to shipwreck along rocky shores. Now, scientists on a research mission to the Ross Ice Shelf may have just inadvertently found the Antarctic analogue to these mythical fiends.
Fortunately, the spine-chilling songs are not likely to mesmerize any sailors; the frequency of the music is far too low to be heard naturally by the human ear. That doesn't make the sounds any less spooky, however.
Researchers first stumbled upon the sounds after placing 34 seismic sensors at various locations deep under the snow layer that sits atop the Ross Ice Shelf, a massive structure that collectively makes up Antarctica's largest ice shelf. The purpose of the research was to monitor changes in how this sensitive shelf shifts and moves with the seasons, and with the rapidly warming climate. They weren't expecting to hear such sinister-sounding songs, however.
"It's kind of like you're blowing a flute, constantly, on the ice shelf,” said Julien Chaput, lead author of the new study, in a press release.
Researchers made the sounds audible by speeding them up around 1,200 times. You can listen yourself by hitting play on the video atop this article.
What's causing the sound?
No Sirens have been discovered making the songs ... not yet anyway. What's actually doing the singing is the landscape itself, as it's blown on by chilling, high-speed winds that sweep across the shelf. As these Antarctic winds whistle over the snow dunes, they create vibrations that can cause even the deep ice to rattle, ever so subtly. Changing air temperatures, as well as the shapes and numbers of dunes, can all affect the pitch of the music.
"Either you change the velocity of the snow by heating or cooling it, or you change where you blow on the flute, by adding or destroying dunes," explained Chaput. "And that's essentially the two forcing effects we can observe."
Studying these sounds, researchers can learn a great deal about a subject far more frightening than mythical monsters. They can learn more about how ice sheets are responding to a world that's rapidly being altered by global warming. Polar regions are undergoing extreme shifts, and the condition of the so-called firn — the ice that's at an intermediate stage between snow and glacial ice — is one of the most important indicators of the health of an ice shelf. This is the layer that researchers can turn their ears toward thanks to this research.
More haunting than a Siren, are the cries of the world's depleting ice shelves. Bone-chilling though they are, let's hope they continue to croon for centuries to come. It will mean that we've at least been able to slow the heedless onslaught of global climate change.