Antarctic ice shelves hide a big secret that threatens our coasts

A new study led by researchers from the University of Cambridge has revealed that Antarctic ice shelves contain significantly more meltwater than previously estimated, with potential implications for global sea level rise.

The research, published in Nature Geoscience, utilised artificial intelligence techniques to map slush - water-soaked snow - across Antarctic ice shelves.

The study found that during the peak of the Antarctic summer, a staggering 57% of all meltwater on ice shelves exists in the form of slush, while the remaining 43% is held in surface ponds and lakes.

This discovery challenges previous assumptions and highlights a critical gap in current climate models.

Dr. Rebecca Dell, the lead author from Cambridge's Scott Polar Research Institute, explained that while satellite imagery has been used to map meltwater lakes, identifying slush has been challenging due to its visual similarity to cloud shadows.

Slush and pooled meltwater contribute to 2.8 times more meltwater formation than predicted. (Photo: AFP)

The team employed machine learning techniques to analyze optical data from NASA's Landsat 8 satellite, enabling them to differentiate slush from other features across 57 Antarctic ice shelves between 2013 and 2021.

The research also uncovered that slush and pooled meltwater contribute to 2.8 times more meltwater formation than predicted by standard climate models. This discrepancy is attributed to the fact that slush and water absorb more solar heat than ice or snow, accelerating the melting process.

The implications of these findings are significant for ice shelf stability and sea level rise predictions. As climate change intensifies, increased meltwater formation on ice shelves could lead to instability or collapse. These floating ice structures act as crucial buttresses against the flow of inland glacier ice into the ocean, which could further affect coastal cities across the world.

Professor Ian Willis, a co-author of the study, emphasized the potential impact of slush on the hydrofracture process, where meltwater weight can create or enlarge icefractures. While slush may not cause hydrofracture in the same manner as liquid water, its presence needs to be considered in future ice shelf stability predictions.

The research underscores the importance of improving climate models to account for the role of slush in Antarctic ice dynamics. As warming continues, regions of Antarctica currently free from water or slush may begin to change, with far-reaching consequences for ice stability and global sea levels.