The floating ice shelf of the Thwaites glacier, one of the biggest in Antarctica and usually described as a “doomsday glacier”, is expected to experience big changes in the next 10 years that would accelerate its break up, according to a new study. This would increase its contribution to global sea level rise by as much as 25%, researchers argue.
The Thwaites glacier is located in West Antarctica and is already dumping 50 billion tons of ice per year. Currently, a third of the glacier flows slower than the rest as it’s locked by a floating ice shelf – a big extension of the glacier held in place by an underwater mountain. This acts as a roadblock, preventing a speedier flow of the upstream ice.
But that block won’t last for long, according to observations by a group of UK and US scientists that are part of the International Thwaites Glacier Collaboration (ITGC). The program collects instrument data throughout the glacier and its adjacent ocean, hoping to better understand the future of the ice sheet and the area where it floats.
A changing glacier
“Thwaites is the widest glacier in the world,” Ted Scambos, a researcher that works as part of the collaboration group, said in a statement. “It’s doubled its outflow speed within the last 30 years, and the glacier in its entirety holds enough water to raise sea level by over two feet. And it could lead to even more sea-level rise, up to 10 feet.”
The researchers at ITGC found that warmer ocean water that circulates below the eastern shelf is reaching the glacier from all angles. This water is thinning and weakening the ice from beneath, causing the glacier to lose its grip on the underwater mountain. There are already massive fractures in place that are expanding even more.
The floating extension of the glacier will likely only last for five more years, the researchers argue, based on satellite data, GPS measurements, and ground-penetrating radar observations. This will result in the glacier contribution to sea-level rise increasing by up to 25%. It currently contributes as much as 4% to the global rise.
“As it’s structured right now this ice shelf acts like a dam, but it’s not going to for very long,” associate Professor Erin Pettit of Oregon State University said at a meeting of the American Geophysical Union (AGU), where the findings were presented. “The collapse of this ice shelf will result in a direct increase in sea level rise pretty rapidly.”
The eastern shelf, with a width of 40 kilometers, currently advances by 600 meters per year. Based on the researchers’ estimations, the speed will soon increase to about two kilometers per year. They have already mapped the weaker and stronger parts of the ice shelf, suggesting a zig-zag pathway the fractures could take across the ice.
As in every recent summer season in Antarctica, the team of scientists is now on their way to the glacier to continue investigating it in every way possible. This includes deploying a submarine that will dive under the floating ice to collect data on water temperature and turbulence – factors that influence the level of melting.
Antarctica is one of the regions of the planet most affected by global warming. While global average temperatures have increased abut 1.1ºC, in Antarctica, they have already reached 3ºC. This has triggered a series of visible effects, causing glaciers to retreat, such as glaciers retreating, turning snow red, and affecting biodiversity – from penguins to polar bears.
The study’s abstract can be accessed here.