Antarctica’s Thwaites Glacier Retreat Faster than Expected – with Spine-Chilling Consequences

“Our results suggest that pulses of very rapid retreat have occurred at Thwaites Glacier in the last two centuries, and possibly as recently as the mid-20th Century,” said Graham.

“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,” said marine geophysicist and study co-author, Robert Larter, from the British Antarctic Survey.  

To collect the imagery and supporting geophysical data, the team, which included scientists from the United States, the United Kingdom, and Sweden, launched a state-of-the-art orange robotic vehicle loaded with imaging sensors called ‘Rán’ from the R/V Nathaniel B. Palmer during an expedition in 2019. Rán, operated by scientists at the University of Gothenburg in Sweden, embarked on a 20-hour mission that was as risky as it was serendipitous, Graham said. It mapped an area of the seabed in front of the glacier about the size of Houston – and did so in extreme conditions during an unusual summer notable for its lack of sea ice. This allowed scientists to access the glacier front for the first time in history.

Anna Wåhlin, a physical oceanographer from the University of Gothenburg who deployed Rán at Thwaites, said, “This was a pioneering study of the ocean floor, made possible by recent technological advancements in autonomous ocean mapping and a bold decision by the Wallenberg foundation to invest into this research infrastructure. The images Ran collected give us vital insights into the processes happening at the critical junction between the glacier and the ocean today.” 

“It was truly a once in a lifetime mission,” said Graham, who said the team would like to sample the seabed sediments directly so they can more accurately date the ridge-like features. “But the ice closed in on us pretty quickly and we had to leave before we could do that on this expedition,” he said.

While many questions remain, one thing’s for sure: It used to be that scientists thought of the Antarctic ice sheets as sluggish and slow to respond, but that’s simply not true, said Graham.

“Just a small kick to Thwaites could lead to a big response,” he said. 

According to the United Nations, roughly 40 percent of the human population lives within 60 miles of the coast. “This study is part of a cross-disciplinary collective effort to understand the Thwaites Glacier system better,” said Tom Frazer, dean of the USF CMS, “and just because it’s 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.”

The study was supported by the National Science Foundation and the UK Natural Environment Research Council through the International Thwaites Glacier Collaboration (ITGC). The 2019 expedition was the first in a 5-year project dubbed THOR, which stands for Thwaites Offshore Research, and also included team members from a sister project called the Thwaites-Amundsen Regional Survey and Network Integrating Atmosphere-Ice-Ocean Processes, or TARSAN.

For more information, read this companion story authored by Graham and the team.