Seafloor Images
NASA/James Yungel/Flickr

Combined research efforts from the United States, the United Kingdom, and Sweden found evidence of a surprising and distressing history in the seabed in front of the Florida-sized Thwaites Glacier in Antarctica. The glacier, which scientists often use to make global sea level rise predictions, is currently in rapid retreat that has experts concerned about the threat to the 40% of the population in locations at risk, and this latest exploration of the seabed suggests the retreat could hasten even further.

The study, part of the five-year-long Thwaites Offshore Research (THOR) project, revolved around the first-ever high-resolution mapping of the area using the sensor-laden “Rán” robotic vehicle. Over a 20-hour period, the team mapped a section of the seafloor in front of Thwaites approximately the size of Houston, Texas.

Through the imaging, the team could gauge the glacier’s past retreat – by examining more than 160 parallel ridges created as Thwaites’s edge moved with the daily tides – and found that the current rate of retreat is slow compared to past rates. The researchers analyzed these half-mile-deep ridges and used computer model-predicted tidal cycles to conclude each rib formed in a single day. The study’s findings suggest that, during the last 200 years, the glacier retreated at a rate more than double the modern rate and its front piece lost contact with a seabed ridge, which creates grim concerns for the future rate of retreat and sea level rise.

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

The team planned to sample seabed sediments so as to better identify the time of rapid retreat, but conditions necessitated an early exit for Rán. The team will look to take those samples during future THOR studies as it works to provide important “essential information to inform global planning efforts.”