Using artificial intelligence techniques, a team of scientists has discovered that at the height of the Antarctic summer in January, more than half (57%) of all meltwater on Antarctic ice shelves remains in the form of slush (water-soaked snow).
This melting, which until now had not been quantified and is not taken into account in climate models, can deeply affect the stability of the ice shelves and accelerate the rise in sea level, warns the study, led by the University of Cambridge (United Kingdom) and published in ‘Nature Geoscience’. Every summer, as the climate warms, water accumulates on the surface of Antarctica’s floating ice shelves.
The melting of the poles in the Arctic and Antarctica is already a fact demonstrated by the international scientific community.
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Previous research has shown that surface lakes of meltwater can contribute to the fracturing and collapse of ice shelves, because the weight of the water can cause the ice to break up but the role of slush in the stability of ice shelves ice is more difficult to determine.
“We can use satellite imagery to map meltwater lakes across much of Antarctica, but it’s hard to map meltwater because it looks like other things, like cloud shadows, when viewed from a satellite,” said lead author Rebecca Dell of the Scott Polar Research Institute (SPRI) in Cambridge.
However, using machine learning techniques, “we can go beyond what the human eye can see and get a clearer picture of how sleet could be affecting the ice in Antarctica,” Dell says.
Satellite data Using optical data from NASA’s Landsat 8 satellite, the team, together with researchers from the University of Colorado Boulder in the United States and the University of Delft in the Netherlands, trained a machine learning model to obtain monthly records of meltwater and meltwater lakes across 57 Antarctic ice shelves between 2013 and 2021.
Since the 1990s, global warming has been twice as fast at the North Pole than anywhere else on the planet.
Photo:Getty
They found that at the height of the Antarctic summer, more than half (57%) of the meltwater on Antarctic ice shelves remains as slush, with the remaining 43% being meltwater.
“This meltwater has never been mapped on a large scale across all of Antarctica’s large ice shelves, so more than half of all surface meltwater has been ignored until now,” says Dell.
Shelf stability Meltwater affects the stability of floating ice shelves that line the Antarctic coast. As the climate warms and melt rates increase in Antarctica, meltwater – either in the form of lakes or meltwater – can seep into and fracture cracks in the ice, potentially leading to the collapse of vulnerable shelves, which in turn would cause ice from inland glaciers to spill into the ocean and contribute to sea level rise.
“Since slush is more solid than meltwater, it won’t cause hydrofracturing in the same way that lake water does, but it’s something we need to consider when predicting whether or not ice shelves will collapse.”says Ian Willis, co-author of the study at the University of Cambridge. Furthermore, it also has a great effect on melting rates.
Because sleet and lakes are less white than snow or ice, they absorb more heat from the sun, causing more snowmelt. This additional melt is not accounted for in climate models, which can lead to underestimation of ice sheet melt projections and ice shelf stability.
“In the future, places in Antarctica that are currently free of water or meltwater are likely to begin to change. As the climate continues to warm, more melting will occur, which could have implications for ice stability and sea level rise,” Willis concludes.
EFE
