Huge red flag for glaciers in the little-studied Antarctic region

The glaciers of Antarctica overturn the concept of “ice rhythm”. A new study of a poorly observed area on the continent finds that increasing heat is accelerating the flow of ice-water streams, which has worrying consequences for sea level rise.

The to study, published this week in Nature Communications, uses a quarter of a century of satellite recordings to observe changes in the Getz Ice Shelf in western Antarctica. The study “is the first to show that this region is accelerating over long multi-year timescales,” lead author Heather Selley said via email. “It is only with detailed maps of the places where change is occurring that we can study the physical process that leads to change.”

Selley explained that while scientists had ever observed changes in the ice level in the Getz area, they couldn’t be sure if it was due to atmospheric processes, such as less snowfall or melting ice. at the surface, or changes in ice speed. The latter is driven by warmer ocean water that undermines the floating ice and highlights the worrying effects of climate change. The new study allows scientists to more concretely link long-term ocean warming to changes in sea ice.

The results are breathtaking. The speed of the 14 glaciers studied increased on average by nearly 23% between 1994 and 2018. Three of these glaciers accelerated by more than 44%. A particularly rapid flow of ice was moving 59% faster than two decades ago.

Ice loss has also increased dramatically. Glaciers lost 315 gigatons of ice – enough to fill 126 million Olympic swimming pools – during that time. And the loss has accelerated considerably in recent years. Between 1994 and 1999 and 2000 to 2009, the area lost 5.6 and 5.8 gigatonnes per year, respectively. But between 2010 and 2018, the rate of ice loss skyrocketed to 24.8 gigatonnes of ice loss per year. This huge loss is responsible for a little more than 10% of Antarctica’s total contribution to sea level rise since the early 1990s.

The Getz Ice Shelf is in an area of ​​tremendous importance for understanding sea level rise, but relatively little is known about the area. Getz isn’t exactly on a list of tourist destinations for Antarctic cruises. It is so remote that no humans have set foot in parts of the region, and nine of the 14 glaciers in the study are not even named.

“There are only a handful of studies on Getz compared to hundreds on glaciers in the Amundsen Sea Sector (Thwaites and Pine Island),” Selley noted. “This study shows that the percentage acceleration of Getz glaciers is comparable to the acceleration measured on Thwaites and Pine Island, showing the importance of the Getz region in relation to the most rapidly evolving glaciers in Antarctica.”

Thwaites and Pine Island are among the most threatened glaciers in Antarctica. Researchers traveling to Thwaites last year pierced the floating portion of the glacier and recorded direct observations warm seawater flowing below. David Holland, a New York University glaciologist who conducted the research, mentionned in a press release at the time, it “suggests that it could experience an unstoppable setback which has enormous implications for the rise in sea levels around the world.”

The new findings concerning the Getz region add another level of concern. Antarctica has a big impact on sea level rise around the world, and understanding how the ice behaves on the continent is increasingly crucial to determining how far down we might be. Additionally, the ice tablets that are collapsing in the area behave much like corks coming out of a bottle of wine, releasing a torrent of ice into the sea and creating more instability and melting in the sea. region. The Thwaites and Pine Island Glaciers, for example, are the cork on land ice that, if submerged in the ocean, could push the seas 10 feet (3.1 meters) or more. It will be important to pay more attention to how little-studied regions like Getz prepare for the future.

“If we don’t understand why the changes are happening, we can’t model the change accurately,” Selley said. “This in turn means that we cannot reliably predict future ice loss and the contribution of Antarctic sea level.”