An unmanned submarine named Ran has made fascinating discoveries beneath Antarctica’s Dotson Ice Shelf before mysteriously going silent. This autonomous vehicle spent weeks mapping the ice’s underside, uncovering structures that challenge our understanding of how melting occurs.
Professor Anna Wåhlin from the University of Gothenburg leads these missions. Her work focuses on how ocean currents erode ice shelves from underneath, impacting glacier stability and future sea levels.
Ran has been busy. During a 2022 mission, it spent 27 days navigating beneath Dotson’s ice, revealing patterns that contrast the eastern and western sides of the shelf. The east melts slowly, while the west shows signs of rapid melting.
Using sonar, Ran mapped 54 square miles beneath the ice. The results were surprising: it found flat areas, terraced steps, and teardrop-shaped pits, all formed by melting from below. These features had remained hidden until now.
Warm Water and Its Impact
Around Antarctica, warm water flows from the Southern Ocean, contributing to the melting of ice shelves like Dotson. Data shows that warm inflows focus erosion on the western side of the shelf, causing significant thinning. In fact, satellite measurements indicate that the ice shelf has been losing about 40 feet of thickness per year at some points.
Interestingly, research indicates that from 1979 to 2017, the Dotson Ice Shelf contributed approximately 0.02 inches to sea level rise. This highlights the critical role of warm currents in shaping ice dynamics.
Curious Structures Under the Ice
Where the currents are slower, the ice bottom looks like step-like terraces formed as melting occurs. In contrast, areas with faster currents are smoother with grooves. The discovery of teardrop-shaped pits, some over 900 feet long, shows how currents can carve unique shapes under the ice.
Ran also captured images of fractures in the ice, some of which have been open since the 1990s. These cracks, widened by melting, can channel warm water, accelerating ice loss.
The Bigger Picture
Since 1979, Antarctic ice loss has contributed to around 0.55 inches of sea level rise. Much of this comes from West Antarctica, where warming currents can reach ice resting above deep basins. When outer ice shelves thin or collapse, it leads to faster glacier flow and rising sea levels.
Understanding how warm water attacks the Dotson’s base gives scientists insight into how other glaciers might react to climate change. Incorporating these findings into climate models will help predict future ice loss.
Technical Challenges and Future Prospects
Ran’s missions are challenging. It must navigate without real-time communication due to the thick ice blocking signals. The team conducted 14 successful missions, collecting invaluable data on ice and ocean interactions.
However, during its last mission, Ran simply vanished after a day underground, leaving the team speculating about mechanical issues or other mishaps. Despite this loss, the data Ran gathered reshapes the understanding of melting patterns beneath ice shelves.
As scientists continue to analyze the detailed maps Ran created, they gain insights into Antarctica’s hidden dynamics. This research is essential for predicting how our planet’s changing climate will affect sea levels in the future.
For more on this research, check out the study published in Science Advances.
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