24 Apr 2024 | West Antarctic Ice Sheet

Accelerated melting of floating portions of ice in Antarctica

The melting of the floating portions of the West Antarctic Ice Sheet is accelerating due to a newly discovered feedback loop, as outlined in a study published in Science Advances. This research sheds light on the mechanisms behind the melting of ice shelves beneath the ocean’s surface, which were previously unclear.

The West Antarctic Ice Sheet has been losing mass in recent decades, contributing to global sea level rise. If fully melted, it could raise global sea levels by approximately five meters. Warm Circumpolar Deep Water (CDW) flowing beneath the ice shelves is melting these shelves from below. Given that much of the West Antarctic Ice Sheet lies below sea level, it is particularly vulnerable to this warm water intrusion.

Previous observations and models showed eastward undercurrents transporting warm water to cavities under the ice shelves, but the driving mechanism remained unclear. The study’s simulations, conducted by researchers from the University of California Los Angeles, MIT, and the University of Southampton, revealed that the deep current carrying warm waters toward the ice shelves is driven by the melting caused by these warm waters.

Researchers found that as the warm water touches the ice, it melts it and mixes with melted ice, creating a swirling motion. This swirling motion pushes more warm water towards the ice, making the melting process even faster. This motion further drives a current along the seafloor slope and carries more warm water toward the ice shelf. As more ice melts, the current strengthens, perpetuating the feedback loop. This feedback loop, not previously accounted for in scientific models, could significantly impact the speed of ice shelf melting and the stability of the West Antarctic Ice Sheet over time.

Losing these floating ice shelves means the glacial ice sheets on land are freed to slide more rapidly into the ocean. Therefore, from New York to Mumbai to Shanghai, millions of people residing in coastal cities are susceptible to sea level rise as the West Antarctic Ice sheet rapidly melts, and over one-third of the world’s population that is found within 62 miles (100 km) of the shore is at risk of coastal flooding. We need drastic and fast paced carbon emission cuts to save our coastal cities.

Read more about sea level rise and global risks.

Link to the above story on Climate Risks Daily: Feedback Loop Accelerating Ice Shelf Melting in West Antarctica Revealed

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Image: Schematic illustrating the mechanism of Antarctic Slope Undercurrent formation (Source: Si, 2024)