Antarctic Ice shelves hold twice as much meltwater as previously thought
New study mapped “slush” using machine learning to better understand meltwater
Slush – water-soaked snow – makes up more than half of all meltwater on the Antarctic ice shelves during the height of summer, yet is poorly accounted for in regional climate models.
Research led by the University of Cambridge, in collaboration with CIRES research scientist Alison Banwell and 2019 Visiting Fellow Ian Willis, used artificial intelligence techniques to map slush on Antarctic ice shelves and found that 57 percent of all meltwater is held in the form of slush, with the remaining amount in surface ponds and lakes.
As the climate warms, more meltwater is formed on the surface of ice shelves, the floating ice surrounding Antarctica which acts as a buttress against glacier ice from inland. Increased meltwater can lead to ice shelf instability or collapse, which in turn leads to sea level rise.
The researchers also found that slush and pooled meltwater lead to 2.8 times more meltwater formation than predicted by standard climate models since it absorbs more heat from the sun than ice or snow. The results, reported in the journal Nature Geoscience, could have profound implications for ice shelf stability and sea level rise.
“Our observation that over half of all surface meltwater on Antarctica’s ice shelves is slush as opposed to ponded meltwater is really important, especially as this slush has been missed out of previous mapping studies,” said Banwell. “Like meltwater, slush has a lower albedo than snow or ice, so it absorbs more heat from the sun, leading to even more melting through a positive feedback chain. So the results of our study have worrying implications for the future stability of Antarctica’s ice shelves.”
