Researchers Accidentally Record Eerie Sound of a Texas-Sized Ice Shelf 'Singing' in Antarctica
Singing is not a trait exclusive to humans. Just like humans, when ice cracks, it sings. Turns out, iceberg songs can be heard quite commonly in Antarctica. In 2014, a team of scientists went around to Antarctica’s Ross Ice Shelf (RIS), hoping to record seasonal changes in the ice shelf. Instead, they ended up documenting an eerie soundscape that'd perfectly fit a Halloween song, a didgeridoo piece, or the background score of a sci-fi movie about aliens. The trail of sound reverberated through the thick ice, as if the weeping ice was shedding frozen tears over the upsetting levels of global warming. The team published their research in the Geophysical Research Letters.
Shaped like a triangle-shaped rift, RIS is the largest ice shelf of Antarctica. Buttressed by glaciers from the East and West Antarctic Ice sheets, RIS is roughly the size of Spain, France, or Texas. Naturally, the ice shelf has long stirred geologists’ curiosity, but never did they think that they’d be welcomed with this bizarre drumroll of seismic tones, the moans and the groans of melting ice. Writing in the paper, the researchers described that they “found strange spectral anomalies that escaped easy explanations, suggesting high frequency trapped seismic waves in the top couple of meters of snow.”
The top couple meters of loose snow is referred to as “firn.” This firn is very vulnerable to the smallest of changes in temperature and wind patterns. When ice experiences disturbances on the surface, they get trapped in the ice as seismic waves that secretly ripple and quiver through the ice shelf. This is why the melting of firn is “considered one of the most important factors in the destabilization of an ice shelf,” Julien Chaput, a geophysicist and mathematician and lead author of the study, told Gizmodo.
Ice shelves are covered in thick blankets of snow that are topped with massive snow dunes, like dunes in a sandy desert. This snow layer acts like a fur coat for the underlying ice, insulating the ice below from heating and even melting when temperatures rise, researchers explained in a press release. So when variations in wind or temperature trigger the melting of ice, the restraining force of this thick blanket loses its power. The glacial water flowing in deeper layers starts spilling more freely into the surrounding lakes. This causes the sea levels to rise and ice to melt.
Chaput and her team tucked 34 ultra-sensitive seismic sensors in deep ice above the firn to map the vibratory structure of the shelf. They studied the data collected from these sensors over 3 years, till 2017. They found that the winds whipping over the snow dunes of RIS were causing the fur coat to constantly vibrate and rumble, as heard in the YouTube video shared by @AGUvideos. These vibrations resembled the “pounding of a colossal drum.” Glaciologist Douglas MacAyeal likened the sound to a large group of buzzing insects or cicada bugs hovering over grasses, per The Miami Herald. American comedian Stephen Colbert described it as the “song of the summer” in his talk show. “It’s kind of like you’re blowing a flute, constantly, on the ice shelf,” Chaput said in the press release.
Even more astonishing was that this seismic hum constantly changed its pitch and frequency. These changes were largely monitored by the changing weather conditions. “Just like musicians can change the pitch of a note on a flute by altering which holes air flows through or how fast it flows, weather conditions on the ice shelf can change the frequency of its vibration by altering its dune-like topography,” Chaput explained. The frequency detected originally was inaudible in the human hearing range, but it was made audible by Chaput who sped it up some 1,200 times. However creepy it may sound, the sound is a valuable nugget that can tell whether RIS is at the edge of an ultimate collapse.