The Brunt Barrier, an ice shelf in Antarctica, cracking, January 25, 2023 ©BelgaImage
Some ice shelves in Antarctica, which researchers thought would remain stable for centuries, are proving vulnerable as the planet warms. This is what emerges from a study by the University of Utrecht, in which the KU Leuven also participated. The results of the study were published Thursday in the scientific journal Nature Climate Change.
When meltwater lakes threaten Antarctica
Ice shelves are floating chunks of ice that are attached to the land and thus form a land ice barrier. If the plates break up, melting land ice can flow faster into the sea, causing sea levels to rise. 75% of Antarctica is surrounded by these ice shelves.
One of the reasons an ice shelf can break off is because of the formation of meltwater lakes. When an ice shelf has cracks, water from these lakes can flow into the cracks. In this way, the plate can break in a short time. More than 60% of Antarctic ice shelves, including the Ross Ice Shelf, the largest ice shelf in the world, have such cracks.
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«That is why it is important to know when and under what conditions such meltwater lakes appear», explains researcher Stef Lhermitte (KU Leuven). “They were generally assumed to form at a temperature of -5°C. We have now plotted the amount of meltwater on an ice shelf once morest the amount of precipitation for the first time».
It is enough to be above -15° C to weaken these platforms
Relatively little snow falls on some ice shelves, such as the Ross Ice Shelf. When a lot of snow falls, it acts like a sponge and prevents the formation of melt lakes. However, it finally turns out that meltwater lakes are already starting to form at an average annual temperature of -15° C. According to the latest climate models, these temperatures might already be reached at the end of this century, with average global warming.
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«The results were logical, but it is remarkable how clear the impact of snow on the threshold of meltwater lake formation is.says Lhermitte. “Antarctica is currently a huge sleeping giant, which is extremely important for global sea level rise, especially for Western Europe. Our research has contributed to a better understanding of this».
