Published in Science Advances, the study highlights previously unknown mechanisms driving the melting of ice shelves beneath the ocean surface.
Significant mass loss from the West Antarctic Ice Sheet in recent years has been a major factor in global sea level rise. Complete melting of this ice sheet would potentially raise global sea levels by approximately five meters.
Research indicates that Circumpolar Deep Water (CDW), significantly warmer than local freezing temperatures, is flowing beneath these ice shelves, causing melting from below. This vulnerability is heightened as much of the ice sheet is below sea level, susceptible to further retreat due to this warm water.
Prior studies and models have shown that eastward undercurrents carry this warm water to cavities under the ice shelves. However, the driving mechanisms of these undercurrents were not well understood until now.
Professor Alberto Naveira Garabato, a co-author from the University of Southampton, explains, "Our findings indicate a positive feedback loop where accelerated ice shelf melting generates more freshwater, strengthening the undercurrent and increasing heat transport to the ice shelves."
"This process could hasten ice shelf melting, potentially destabilizing the West Antarctic Ice Sheet in future," he added.
Researchers from the University of California Los Angeles, MIT, and the University of Southampton employed high-resolution simulations to study the dynamics involved.
Dr. Alessandro Silvano, also from the University of Southampton, noted, "The simulations demonstrate that the deep current carrying warm waters to the ice shelves is propelled by the melting it induces."
These models show that when CDW interacts with the ice shelf, it melts the ice, mixing with the lighter, melted freshwater. This mixture rises, stretching the CDW layer vertically, creating a swirling motion. If a coastal trough is present, this motion can drive a current along the seafloor slope, directing more warm water towards the ice shelf.
The formation of this underwater current occurs further from the ice shelf, strengthening as more ice melts and pushing even more warm water towards it.
Dr. Silvano emphasized, "Models that exclude cavities under ice shelves likely miss this positive feedback loop. Our findings suggest it is a critical factor affecting ice shelf melt rates and the overall stability of the West Antarctic Ice Sheet."
Research Report:Antarctic Slope Undercurrent and onshore heat transport driven by ice shelf melting
Related Links
University of Southampton
Beyond the Ice Age
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