Doomsday Glacier map to shed light on future sea levels

A team from the British Antarctic Survey has completed the first map of the ground beneath West Antarctica's Doomsday Glacier, which is the size of Great Britain and could raise global sea levels by 65 cm (25 in) in the coming centuries as it melts.

Covering an area of 192,000 km² (74,000 miles²), Thwaite Glacier got the nickname Doomsday Glacier because it's the widest glacier in the world and its retreat and instability has raised fears that it could collapse, significantly raising sea levels.

The likelihood of this happening in the near future depends on a number of factors, not the least of which is the ground that Thwaite rests on – especially the leading edge that sits below sea level where it is most susceptible to melting.

To learn more about this, the BAS team used a number of different methods to find out what lies below the ice, including aircraft-mounted deep-penetrating radar as well as gravity and magnetic sensors. No single sensor could produce a complete survey, but by using multiple approaches, it allowed for overlaps to fill in the gaps and create a 3D map of the glacier and the underlying geology.

The worst case scenario would have been for the glacier to be resting on a layer of sediment that would act like slippery mud, speeding up its movement. Instead, what the team found was a complex geological patchwork dating back 100 million years, the time when New Zealand parted company with Antarctica.

In place of a thick layer of sediment, most of the ground was made up of granite and other igneous rocks, with the sediments resting in a series of basins sitting toward the back of the glacier. Exactly how this will affect the speed of Thwaite's retreat or how much the melting water will raise sea levels is still to be determined, but given that Thwaite glacier accounts for 4% of present sea level rises, it's an important question to consider.

"We hope that by showing the detailed geology, and how it correlates with the basal friction, future models of glacial retreat will have lower uncertainty, as the controls of the basal processes will be better understood," said Dr Tom Jordan, a geophysicist with the British Antarctic Survey (BAS). "No single scientific study could ever match the sheer scale and challenge of climate change. But it is the incremental building of all the individual scientific studies like this that allows us to understand and tackle that challenge."

The research was published in Science Advances.

The video below discusses the Thwaite glacier survey.

Source: British Antarctic Survey