Antarctic ‘Doomsday Glacier’ at risk of receding faster than previously feared

A new study of the Antarctic seafloor suggests that the massive Thwaites Glacier, part of a larger ice sheet, could start receding faster and hasten a rise in sea levels.

The Thwaites Glacier, also known as the Doomsday Glacier for its potential to rise sea levels when it melts, is at risk of short, sudden periods of extreme melting, according to the study.

The glacier currently melts at an annual rate of about 1,000 feet to about 3,300 feet, contributing to 4% of the global rise of sea levels, the study’s authors wrote at Nature.com.

The glacier is already considered to be in fast retreat. Scientists now discovered that sometime in the past two centuries, the front of the glacier rapidly separated from the seabed ridge and retreated at a rate of more than 1.3 miles per year. That’s twice the rate observed with the use of satellites over the past decade, according to the study.

The study was conducted by University of South Florida marine geophysicist Alastair Graham and international partners.

Together with neighboring glaciers, the Thwaites Glacier “holds back enough continental ice to raise sea level by more than a meter (slightly more than one yard),” the scientists wrote.

The study also noted that a total loss of the glacier and surrounding icy basins could raise the sea level from three to 10 feet.

Unlike glaciers tied to a continental ice sheet, warm ocean water can undermine the Thwaites Glacier from beneath, eroding its connection to the seabed. The loss of support, along with greater exposure to more warm water, speeds up the receding process.

“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,” study co-author Robert Larter said.

The study looked at the seafloor almost 2,300 feet beneath the Thwaites Glacier.

An area of particular interest showed ridges in the sediment from the glacier waxing and waning on the seabed for centuries. This area was around the size of Houston, Texas; the glacier altogether is about the size of the state of Florida.

The team documented more than 160 parallel ridges that were created, like a footprint, as the glacier’s leading edge retreated and bobbed up and down with the daily tides.