Thwaites Glacier, capable of raising sea levels by several feet, 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 likely do in the future. They found that sometime in the past two centuries, the base of the glacier broke away from the sea floor and retreated at a rate of 1.3 miles (2.1 kilometers) per year. That’s double the rate scientists have observed in the past decade or so. This rapid decay likely occurred “as recently as the middle of the 20th century,” Alastair Graham, the study’s lead author and a marine geophysicist at the University of South Florida, said in a news release. It suggests that Thwaites has the potential to undergo a rapid retreat in the near future once it recedes past a ridge of seafloor that helps keep it in check. “Thwaites is really holding on today, and we should expect to see big changes over short periods of time in the future — even from one year to the next — once the glacier retreats past a shallow ridge in the bed of,” Robert Larter, a marine geophysicist and one of the study’s co-authors from the British Antarctic Survey, said in the release. 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 just a portion of the West Antarctic Ice Sheet, which contains enough ice to raise sea levels as much as 16 feet, according to NASA. As the climate crisis has accelerated, this region is being watched closely because of its rapid melting and capacity for widespread coastal destruction. Thwaites Glacier itself has concerned scientists for decades. As early as 1973, researchers questioned whether it was at high risk of collapse. Nearly a decade later, they discovered that—because the glacier is grounded on the sea floor rather than on dry land—warm ocean currents could melt the glacier below, causing it to destabilize below. Because of this research, scientists began to call the area around Thwaites the “weak bottom of the West Antarctic Ice Sheet.” In the 21st century, researchers began documenting the rapid decline of Thwaites in an alarming series of studies. In 2001, satellite data showed that the ground line was receding by about 0.6 miles (1 km) per year. In 2020, scientists found evidence that warm water was indeed flowing at 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 prevents ice from flowing freely into the ocean, could break up within five years. “From the satellite data, we see these large fractures spreading across the surface of the ice shelf, effectively weakening the ice fabric, sort of like a windshield crack,” said Peter Davis, an oceanographer at the British Antarctic Survey. CNN in 2021. “It’s slowly spreading across the ice sheet and eventually it’s going to break into many different pieces.” Monday’s findings, which suggest the Thwaites are capable of receding 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 news 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 sea floor so they can determine when the previous rapid retreats took place. 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 small kick to the Thwaites could lead to a big response,” Graham said.
