Last updated June 26, 2018 at 11:41 am
Very fluid mantle pushing up ‘memory foam’ crust by four centimetres a year.
The Earth’s crust in West Antarctica is rising at one of the fastest rates of any glaciated area on the planet, scientists using GPS data have found.
They say the bedrock is being pushed up by the fluid mantle by 41 millimetres a year, compared with 30 millimetres a year in Greenland. And it is getting faster. In 100 years, the uplift rate will be up to three and a half times faster than they are now, the study found.
But the discovery is actually good news and could, the scientists say, help stabilise the ice sheet and slow the rise in sea levels.
“It’s good news for Antarctica,” lead author Valentina Barletta of the Technical University of Denmark and Ohio State University told reporters.
Much of the West Antarctic ice sheet rests on the seabed and is held down by the weight of ice above. As it rises rapidly the ice sheet will be lifted on to land where it is less likely to break up than it would be under warming ocean water.
Barletta said the Earth was rising a bit like a hard memory-foam mattress
“When the ice melts and gets thinner, Earth re-adjusts and immediately rises by a few millimetres, depending on the amount of ice lost,” she says. “It re-adjusts slowly for several thousand years after the melting. In Scandinavia, the bedrock is rising by about 10 mm a year.”
But rather than thousands of years, in the Amundsen Sea Embayment the process is taking place over centuries or even decades.
“This tells us that the mantle below is very fluid and moves quickly when the weight of the ice has been removed,” Barletta said.
The team made their measurement using GPS sensors placed on bedrock around the Amundsen Sea, but were confirmed by data from the European Space Agency’s GOCE mission, which ended in 2013.
Standing for the Gravity Field and Steady-State Ocean Circulation Explorer, GOCE mapped tiny variations in Earth’s gravity field to generate a model, which is used to investigate the structure of inner Earth.
Jörg Ebbing from Kiel University in Germany and who runs ESA’s GOCE+Antarctica study, said, “GOCE has revolutionised the ability to study Earth’s global gravity field.
“It allows us to probe deep into the Earth’s interior. We can model the structure of the lithosphere using both gravity and seismic data.
“Understanding Earth’s interior is extremely important if we are to comprehend the state of our planet, including its resources and hazards.”
The paper was published in Science.