Antarctica's hidden channels beneath ice sheets are a terrifying secret that could put the world at risk. A new study has revealed that these channels can trap warm water and accelerate the ice's deterioration, leading to instability that causes land ice in Antarctica to flow into the ocean. This small-scale warming process needs to be included in future models to form a more accurate picture of how sea-level rise will impact the world in coming decades.
The Fimbulisen Ice Shelf in East Antarctica is an especially cold part of the frozen continent, making it less vulnerable than the Thwaites Glacier in warmer West Antarctica. However, scientists from the iC3 Polar Research Hub in Tromsø, Norway, have discovered hidden mechanisms beneath the Fimbulisen Ice Shelf that could radically alter our sea level rise timeline.
The study, published in the journal Nature Communications, found that the shape of the ice shelf underside is not just a passive feature. It can actively trap ocean heat in exactly the places where extra melting matters most. Underneath the Fimbulisen Ice Shelf, small channels can create circulation systems that keep warm water trapped against the glacier itself, increasing the melting rate by an order of magnitude and leading to other instabilities that leave the ice shelf more vulnerable than scientists originally expected.
Exploring the underside of a glacier is far from easy. In early 2024, an underwater research project by the University of Gothenburg suffered a huge setback when its AUV submersible "Ran" disappeared beneath the icy depths of Thwaites Glacier. In the current study, scientists used a detailed map of the underside of the Fimbulisen Ice Shelf coupled with advanced modeling of the ocean cavity that lies beneath it. They then compared two ice-shelf-underside conditions—smooth or channeled—in both cooler and warmer water conditions, which gave them a good idea of how the channels impact temperature and water mixing.
The study found that even small amounts of warmer water can substantially increase melting within the channels. As a result, the channels can grow and, in the worst case, weaken the stability of the entire ice shelf. If these channels do indeed grow in size and weaken the overall structure, they may eventually cause the ice shelf to fail and allow land ice to flow into the ocean. In 2023, National Oceanic and Atmospheric Administration (NOAA) scientist Nicole Schlegel explained why such an outcome could be disastrous.
"Thousands of meters of ice sit on land," Schlegel said in a NASA press statement. "If the ice shelves are thinned or changed, then that decreases their ability to hold back the ice that’s on the land. More interior ice comes into the ocean, it speeds up, then you have a contribution to sea level rise."
Future models will have to include what the researchers call "small-scale melting processes" that can end up having very large consequences. If not, humanity could end up forging ahead without knowing just how great the threat truly is.
