Rapidly retreating doomsday glacier clinging ‘by its fingernails,’ study confirms

New research unveiled Monday suggests that the West Antarctic Thwaites Glacier—an enormous ice mass with the potential to trigger catastrophic sea level rise—could retreat far more quickly in the coming years than scientists previously anticipated as fossil fuel-driven planetary warming continues to accelerate.

Dubbed the “Doomsday Glacier,” Thwaites has been the subject of scientific concern for decades given its immensity—it is roughly the size of the U.S. state of Florida and, if melting continues at the current pace, it could raise global sea levels by 11 feet or more.

But a new study published in Nature Geoscience offers a first-of-its-kind look at the body’s transformation over time, finding that “sustained pulses of rapid retreat have occurred at Thwaites Glacier in the past two centuries.”

“Over a duration of 5.5 months, Thwaites’ grounding zone retreated at a rate of >2.1 km per year—twice the rate observed by satellite at the fastest retreating part of the grounding zone between 2011 and 2019,” the analysis notes. “Similar rapid retreat pulses are likely to occur in the near future when the grounding zone migrates back off stabilizing high points on the sea floor.”

Robert Larter, a marine geophysicist with the British Antarctic Survey, saidMonday that the research shows Thwaites “is really holding on today by its fingernails, and we should expect to see big changes over small timescales in the future—even from one year to the next—once the glacier retreats beyond a shallow ridge in its bed.”

To explore past changes to the glacier and help chart out its possible future, a team of scientists led by Alastair Graham of the University of South Florida’s College of Marine Science traveled to West Antarctica to observe the sea floor in front of Thwaites using a sensor-equipped autonomous submarine.

“Over two extended survey missions, we targeted submarine troughs previously hypothesized as conduits for warm water access to the glacier grounding line,” Graham and study co-authors Lauren Simkins and Anna Wåhlin wrote in a summary of their expedition. “At both sites, the sea-floor also comprised of sills that likely served as former stabilizing points for the grounding zone of Thwaites. “

“For Thwaites, the importance of our results lies in two take-home messages. The first is that Thwaites has undergone significantly faster rates of retreat in the past than it is experiencing right now,” they continued. “This finding raises the potential upper ‘speed limit’ on our expectations for Thwaites behavior in the near future.”

“Second, our results show that very short (several months duration) pulses of non-linear grounding zone retreat occur, especially where the ice is retreating from flattish sea floors or flat-topped ridges,” they added. “These phases of rapid retreat are corroborated by modern observations, and demonstrate, collectively, that drastic changes in grounding line position might be expected, even from one field season to the next.”

In a statement, Graham warned that “just a small kick to Thwaites could lead to a big response.” Researchers have cautioned that several feet of global sea level rise could have devastating consequences, displacing tens of millions of people.

Tom Frazer, dean of the University of South Florida’s College of Marine Science, said that just because the glacier is “out of sight, we can’t have Thwaites out of mind.”

“This study is an important step forward in providing essential information to inform global planning efforts,” Frazer added.