In the fight against climate change, a new frontier has come forward: the stability of Antarctic ice shelves. Recent field research, led by the Cooperative Institute for Research in Environmental Sciences, or CIRES, showed that these enormous structures of ice are not simply bending under the weight of meltwater but are actively fracturing. This has big implications for global sea levels and-in turn-coastal security.
Antarctica’s ice shelves serve as crucial brakes and prevent glacier ice from directly surging into the ocean. However, as air temperatures rise, glacier ice is melting and forming pools on these floating ice shelves substantially increasing their weight. The added weight bends the ice, and, as scientists have only recently discovered, it also causes it to fracture. This fracturing can lead to the sudden collapse of these ice shelves, accelerate sea level rise, and thus have a potentially disastrous outcome for coastlines around the world.
“Ice shelves are extremely important for the Antarctic Ice Sheet’s overall health as they act to buttress or hold back the glacier ice on land,” said Alison Banwell, a CIRES scientist at the Earth Science and Observation Center. Her new study, published in the Journal of Glaciology, represents the first field-based observation of ice shelves fracturing from surface meltwater.
Banwell and her research team from the University of Cambridge, University of Oxford, and University of Chicago did their research on the George VI Ice Shelf in the Antarctic Peninsula. In November 2019, they installed a camp next to a surface depression that was known to gather meltwater on the surface of the ice. With high-precision GPS stations, water-pressure sensors, and a time-lapse camera setup, they recorded changes on the ice surface in great detail.
Work resumed in November 2021 after being disrupted due to the COVID-19 pandemic. The remaining instruments picked up records of significant ice movement and the formation/drainage of a meltwater lake during the record-high melt season of 2019/2020. The data indicated that the weight of meltwater accumulated was causing the center of the lake’s ice to flex downward about a foot, and the horizontal distance between the edge and center of the lake was growing, too, showing that circular fractures were both initiating and widening.
“This is an exciting discovery,” Banwell said. She believes these kinds of circular fractures were integral in the chain reaction style lake drainage process that helped to break up the Larsen B Ice Shelf in 2002. Thousands of meltwater lakes suddenly drained, which contributed to the shelf’s collapse.
This has implications that are far more than academic. It will be useful to improve models of the stability of Antarctic ice shelves, as it is then that the particular conditions under which fracture occurs become understandable. This knowledge is important to anticipate what the consequences of these collapses mean in terms of global sea levels and coastal security.
Indeed, the growing evidence bolsters the urgency of addressing the causes of climate change even clearer. Antarctic ice shelves are a reminder of wider impending environmental problems that require ongoing scientific research and care for the environment to resolve such global threats.