Thwaites Glacier, capable of raising sea levels by several meters, is eroding along its underwater base as the planet warms. In a study published Monday in the journal Nature Geoscience, scientists mapped the glacier’s historical retreat, hoping to learn from its past what the glacier will do in the future.
They found that sometime in the past two centuries, the base of the glacier broke away from the seafloor and retreated at a rate of 2.1 kilometers per year. That’s double the rate scientists have observed over the past decade or so.
This rapid decay possibly occurred “as recently as the mid-20th century,” Alastair Graham, lead author of the study and a marine geophysicist at the University of South Florida, said in a news release.
It suggests that the Thwaites have the ability to undergo a rapid retreat in the near future, once it recedes past a seafloor ridge that helps keep it in check.
“Thwaites is really holding on today by its fingernails, and we should expect to see big changes on small time scales in the future, even from year to year, once the glacier retreats beyond a shallow ridge in his bed,” Robert. Larter, a marine geophysicist and one of the co-authors of the British Antarctic Survey study, said in the statement.
The Thwaites Glacier, located in West Antarctica, is one of the widest on Earth and is larger than the state of Florida. But it’s only a fraction of the West Antarctic Ice Sheet, which contains enough ice to raise sea levels up to 16 feet, according to NASA.
As the climate crisis has accelerated, this region has come under close scrutiny because of its rapid melting and capacity for widespread coastal destruction.
Thwaites Glacier itself has worried scientists for decades. As early as 1973, researchers wondered if it had a high risk of collapse. Almost a decade later, they discovered that because the glacier sits ashore on a sea floor, rather than dry land, warm ocean currents could melt the glacier from below, causing it to destabilize from below.
It was because of this research that scientists began to call the region around the Thwaites the “Weak Bank of the West Antarctic Ice Sheet”.
In the 21st century, researchers began to document the rapid retreat of the Thwaites in an alarming series of studies.
In 2001, satellite data showed that the ground line was receding about 0.6 miles (1 kilometer) per year. In 2020, scientists found evidence that warm water was flowing through the base of the glacier, melting it from below. And then, in 2021, a study showed that the Thwaites Ice Shelf, which helps stabilize the glacier and prevent ice from flowing freely into the ocean, could break up within five years.
“From the satellite data, we’re seeing these large fractures extending across the surface of the ice shelf, essentially weakening the fabric of the ice — a bit like a windshield crack,” said oceanographer Peter Davis of the British Antarctic Survey. CNN in 2021. “It’s slowly spreading across the ice shelf and will eventually break up into many different pieces.”
Monday’s findings, which suggest the Thwaites is capable of retreating at a much faster rate than recently thought, were documented in a 20-hour mission in extreme conditions that mapped an underwater area the size of Houston, according to a press release.
Graham said this research “was really a once-in-a-lifetime mission,” but that the team hopes to return soon to collect samples from the seafloor so they can determine when the previous rapid retreats occurred. That could help scientists predict future changes in the “doomsday glacier,” which scientists had previously assumed would be slow to change, something Graham said this study disproves.
“Just a little kick to the Thwaites could trigger a big response,” Graham said.