Footage shows the Thwaites’ underbelly is melting much faster and will be gone soon.

Using a torpedo-shaped undersea robot called IceFin, scientists have filmed the famous Thwaites Glacier’s underbelly, concluding from the video that it’s melting at a much faster speed that calculated earlier and will disappear relatively soon.

The Florida-sized ice shelf floating off the coast of Antarctica will cause the ocean level to rise about 30 centimeters within a few years, if it collapses, while its complete destruction will add a volume pushing water level another three meters by tugging nearby chunks of ice, a group of scientists explained in two papers (one, two) for the journal Nature. 

Location of the Thwaites Glacier in Antarctica. Credit: RBS

Researchers said after examining what is called the Doomsday giant that it is fairly simple underneath, flat underside, though the robot found that 10 percent of it is way more complex.

There are terraces, for instance, of vertical walls over 9 meters high where melting is happening much faster than in flat areas. That small portion is contributing 25 percent of the melting that they could see.

And it’s even worse: as those features melt, they may be sending shocks through the system.

The Thwaites’ melting isn’t due to rising atmospheric temperatures above, but from rising ocean temperatures below. Its grounding line has retreated some 16 kilometers inland since the late 1990s, which means that now more of the glacier’s ice is making contact with warm saltwater.

Icefin also measured the salinity, temperature, and oxygen content of the water, giving scientists fresh data to compare with past figures.

They observed that where the glacier’s underside is smoother, melting is happening at a much slower rate than where the topography is jagged. That’s because a layer of cold water rests where the ice is flat, insulating it from warmer ocean water like a liquid blanket. But where the topography is sloped and irregular, there are more vertical surfaces where warm water can attack the ice, including making incursions from the side, the study said.

Understanding how Thwaites Glacier is breaking apart is important to figure out how quickly it will make sea levels rise. Right now, scientists use simple models to predict this, assuming the ice underneath is mostly flat or sloped. That's because they lacked advanced tools like IceFin to explore these areas in detail or computer power to process data about a complex and vast region.

The discoveries made by Icefin help make better models of the glacier. It's like a puzzle piece that helps us understand the stability of Antarctica.  

More videos about the glacier are here.