An Antarctic iceberg at sunset.

An Antarctic iceberg at sunset.
Photo: Sergio Pitamitz / VWPics (AP)

The Thwaites Glacier, one of the most unstable parts of Antarctica’s ice sheet, could be gearing up for even more rapid changes than we previously thought. In a study published this week in Nature Geoscience, a team of researchers have published new images of the ocean’s floor that they say provide valuable information about how the glacier may have retreated during past warm periods. The insights could give a scary warning about the future of sea level rise.

“Thwaites is really holding on today by its fingernails, and we should expect to see big changes over small timescales in the future–even from one year to the next–once the glacier retreats beyond a shallow ridge in its bed,” study co-author Robert Larter from the British Antarctic Survey said in a press release.

Scientists have known for decades that the Thwaites Glacier, known colloquially as the Doomsday Glacier, is in trouble. In recent years, studies have found that not only is the massive glacier, which floats over the Amundsen Sea in West Antarctica, receding at a particularly alarming rate, but that warm ocean water is now mixing under the glacier, which could further destabilize it. If the 74,000-square-mile glacier collapses, it contains enough water on its own to potentially make sea levels around the world rise by anywhere from 3 to 10 feet (0.9 to 3 meters), as well as put other parts of the West Antarctic Ice Sheet at more risk of collapse. Understanding how quickly glaciers like the Thwaites respond to new inputs is vital for trying to project various sea level rise scenarios under climate change.

The study looks at ridges 700 meters under water on the seafloor, which help to provide a topographic map of sorts to document the glacier’s movements. A robotic vehicle collected the images of the ridges in 2019. These ridges reveal that about 100 years ago, the glacier sped up considerably, moving for a short period of time at about 1.3 miles (2.1 kilometers) per year. That’s about twice the rate that it’s currently moving today.

“You could say that’s good news because it’s not so bad now compared to what it was in the past,” Anna Wåhlin, one of the study’s co-author, told NBC News. “But you can also say that it’s bad news, because it could happen again.”

And, the study points out, once the glacier retreats beyond a certain ridge that’s helping to hold it back, it could be in for a lot of rapid changes—ones that previous studies have chronicled as potentially helping to destabilize the glacier even further over the next few decades.

“Just a small kick to Thwaites could lead to a big response,” the study’s lead geophysicist Alastair Graham said in the release.

Source