Recent expeditions to the Dotson Ice Shelf in West Antarctica have uncovered unusual and never-before-seen patterns beneath the ice.
These discoveries, made possible through advanced underwater mapping techniques, provide new insights into the melting processes of Antarctica’s ice shelves, contributing to our understanding of how glaciers erode and their potential impact on sea levels.
Unveiling the Hidden Underside of the Ice Shelf
Scientists from the University of Gothenburg and the University of East Anglia led an expedition to map the underside of the Dotson Ice Shelf. Utilizing a remotely operated vehicle (ROV) named “Ran,” the team conducted a comprehensive survey of the glacier’s underside, traveling more than 600 miles (1,000 kilometers) and reaching depths of 1,150 feet (350 meters). This endeavor aimed to create the most detailed picture ever of the glacier’s base.
“In order to understand the ice cycle in Antarctica and how ice gets from the continent into the ocean, we need to understand how it melts from beneath, a process that is equally important as calving for moving land ice to the ocean,” said Anna Wåhlin, a professor of oceanography at the University of Gothenburg.
Discovering Unusual Patterns
The survey revealed unexpected teardrop-shaped formations on the glacier’s base, some extending up to 1,300 feet (400 meters) long. These shapes were discovered amidst peaks and valleys in the ice, indicating that the glacier’s underside is not smooth as previously thought. The researchers believe these patterns result from uneven melting caused by water currents influenced by Earth’s rotation.
“If you look closely at the shapes they are not symmetrical, they are bent a bit like blue mussels, and the reason for that asymmetry is Earth’s rotation,” Wåhlin explained. “Water moving on Earth is subject to something called the Coriolis force, which is acting to the left of the direction of motion in the Southern Hemisphere. If we are correct, there is a force balance in the layer closest to the ice where friction is balanced by the Coriolis force.”
Advanced Techniques and Their Implications
The researchers employed advanced multibeam sonar systems to map the ice shelf’s underside, revealing detailed images and providing new data on the glacier’s melting processes. These high-resolution images captured by the ROV showed that the ice melts faster at points where underwater currents erode its base, and fractures in the glacier facilitate the upward travel of meltwater.
“We have previously used satellite data and ice cores to observe how ice shelves change over time. By navigating the submersible into the cavity, we were able to get high-resolution maps of the ice underside. It’s a bit like seeing the back of the moon for the first time,” said Wåhlin.
The Broader Impact of Melting Ice Shelves
Understanding the melting processes of ice shelves is crucial for predicting future sea level rise. Although the melting of floating ice shelves does not directly contribute to sea level rise, it destabilizes the glaciers behind them, causing them to flow faster into the ocean and thus raising sea levels.
Prof. Karen Heywood from the University of East Anglia emphasized the importance of these findings. “These ice shelves are already floating on the sea, so their melting doesn’t directly affect sea level. However, ultimately the melting of ice shelves causes the glaciers on land further upstream to flow faster and destabilize, which does lead to sea level rise,” she said.
Challenges and Future Research
The team’s January 2024 follow-up expedition faced challenges when the ROV disappeared beneath the ice shelf after completing one dive. Despite this setback, the data collected has provided valuable insights, and researchers plan to continue their investigations with new equipment.
“The mapping has given us new data that we need to look at more closely. It is clear that many previous assumptions about melting of glacier undersides are falling short. Current models cannot explain the complex patterns we see. But with this method, we have a better chance of finding the answers,” Wåhlin stated.
The research, published in the journal Science Advances, highlights the need for improved models to predict the melting rates of ice shelves and their impact on global sea levels. By combining remote sensing with oceanographic field data, scientists hope to gain a deeper understanding of the processes driving these changes.
