Data from a comprehensive study into Thwaites Glacier is painting a bleak picture. An international research team has found that a protective ice shelf will likely collapse within five years, which will speed up the destabilization of the West Antarctic ice sheet.
Thwaites Glacier spans 120 km (75 miles) along the west coast of Antarctica, and it’s a key focus for climate scientists, including the International Thwaites Glacier Collaboration (ITGC). This large glacier is particularly vulnerable to climate change – and the effects of its demise would be devastating.
“Thwaites is the widest glacier in the world,” says Ted Scambos, US lead coordinator for ITGC. “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 2 ft (0.6 m). And it could lead to even more sea-level rise, up to 10 ft (3 m), if it draws the surrounding glaciers with it.”
Recognizing those stakes, the ITGC was formed in 2018 to study Thwaites Glacier and monitor changes over five years. Almost 100 scientists are involved, collecting data on the ice and the surrounding water, and modeling changes into the future.
One of the most important structures is the Thwaites Eastern Ice Shelf, a floating mass of ice that braces about a third of the glacier, slowing the speed at which ice flows into the ocean. The ice shelf itself is pinned to an underwater mountain, which has kept it and the glacier relatively stable.
If Thwaites were to collapse, it would drag most of West Antarctica’s ice with it
But the ITGC found that the Thwaites Eastern Ice Shelf is under assault from multiple angles. Long channels are forming underneath the ice shelf, which allows water to flow more easily and melt the ice more efficiently.
Radar imagery shows large cracks are propagating towards the center of the ice shelf at a rate of up to 2 km (1.2 miles) per year. Worse still, these cracks are heading right for a weak zone of thin ice, which would trigger a zigzag rift pattern that would ultimately cause the entire ice shelf to collapse. The researchers calculate that this is likely to happen in as little as five years – and once the ice shelf is gone, the glacier will destabilize faster.
The mainland section of Thwaites Glacier is already under threat too. A submarine robot was sent down to examine the grounding zone, where the ice is anchored to the bedrock below. They found that the ocean water there is relatively warm and salty, which is melting the ice from underneath. Worse still, the floating ice shelf rises and falls with the tide, which works to pump water towards the glacier’s grounding zone.
The team also modeled what would happen as Thwaites Glacier retreats further inland. Very tall ice cliffs are likely to form along the ocean front, which can break off into the sea and lead to a very rapid retreat of the glacier and eventually, a collapse. This, the team says, could happen within a few decades or a few centuries.
“If Thwaites were to collapse, it would drag most of West Antarctica’s ice with it,” says Scambos. “So it’s critical to get a clearer picture of how the glacier will behave over the next 100 years.”
The ITGC will continue to study Thwaites Glacier for the next three years. The current work was presented at the AGU Fall Meeting.
Source: CIRES
