Antarctica's vast Ross Ice Shelf has been "caught" in remarkable new observations – something that could help scientists track their changes remotely.
Winds blowing across snow dunes on the shelf cause the surface of the Texas ice sheet to vibrate and produce an almost constant set of seismic "sounds" described in a recent study just released.
The Ice Shelf ̵
Much of this was due to the Ross dependency claimed by New Zealand.
It supported adjacent ice sheets on mainland Antarctica and prevented ice flow from land to water, like a cork in a bottle.
As ice shelves collapsed, ice flowed more quickly from land into the sea, increasing the sea level.
Shelf shelves throughout Antarctica have been thinned out, and in some cases have shattered or retreated, b Due to rising ocean and air temperatures.
Earlier observations have shown that Antarctic ice floes can collapse suddenly and without obvious warning signs, which occurred when the Larsen B ice shelf on the Antarctic Peninsula suddenly collapsed in 2002.
To better To understand the physical properties of the shelf, researchers buried 34 sensitive seismic sensors under their snow-covered surface.
The sensors enabled researchers to monitor the shakes of the ice shelf and study its structure and movements for more than two years from late 2014 to early 2017
Ice shelves are covered with thick, often several meters deep, snow cover covered with massive snow dunes, like sand dunes in a desert.
This layer of snow acts as a fur coat for the underlying ice, insulating the underlying ice by heating and even melting at elevated temperatures.
When the researchers began to analyze seismic data on the shelf, they noticed something strange: their fur
Looking closer at the data, they discovered winds blowing over the massive snow dunes and the snowstorm of the ice sheet Knocking caused a colossal drum.
They also noticed the pitch of this seismic buzzing changed as the weather changed the surface of the snow layer.
They found the ice vibrating on different frequencies when strong storms rearranged the snow dunes or when the air temperatures went up or down at the surface, what the seismic speed changed waves went through the snow.
"It's a way you blow a flute, constantly, on the ice shelf," said Julien Chaput, a geophysicist and mathematician at Colorado State University, and lead author of the new study.
Just as musicians could change the pitch of a note on a flute by changing which holes flowed through the air or how fast it flowed, the weather conditions on the ice shelf could change the vibration frequency. "Chaput explains that changing his dune-like topography . "
"Either you change the speed of the snow by heating or cooling, or you change where you blow on the flute by adding or destroying dunes," he said. 19659002] "And these are essentially the two forced effects we can observe."
The hum was too low to be audible to human ears, but the new results suggest that scientists using seismic stations could continuously monitor ice shelf conditions in near real time.
Examining the vibrations of an insulating snowpack on an ice shelf could give scientists a sense of how they are responding to changing climatic conditions, said Douglas MacAyeal, a glaciologist at the University of Chicago.
Changes The seismic humming of the ice shelf could indicate whether melting ice or cracks have formed in the ice, which could indicate whether the ice shelf is fragile.
"The ice shelf response shows us that we can very well track sensitive details about it," Chaput said.
"Basically, we have a tool to really monitor the environment and its impact on the ice shelf."
When the Ross Ice Shelf collapses, scientists say it will have a significant impact on global sea-level rise.
The wider West Antarctic ice sheet stores an equivalent sea level rise of 3.2 m, while the much larger East Antarctic ice sheet contains an estimated 58 m of sea level rise.
Before 2012, Antarctica lost ice at a steady rate of 76 billion tons per year – a 0.2 mm per year contribution to sea-level rise
But since then, there has been a strong tripling.
Between 2012 and 2017, the continent lost 219 billion tons of ice per year – a contribution of 0.6 mm per year.
And between 1992 and 2017, the Antarctic ice sheet lost about three trillion tons of ice – an average sea-level rise of about 8 mm.
During these 26 years, ocean-driven melting tripled West Antarctic ice loss rates, from 53 billion to 159 billion tons per year
The rate of ice loss from the Antarctic Peninsula increased from about 7 billion to 33 billion tons per year Year as a result of the collapse of the ice sheets.
In the West Antarctic, ice shelves were eaten by warm seawater and those in the waters of Amundsen and Bellingshausen are up to 18 percent thinner than in the early 1990s.
On the Antarctic Peninsula, where air temperatures rose sharply, the ice floes collapsed when their surfaces melted.
In total, 34,000 square kilometers of ice-floe had been lost since the 1950s.