Scientists are concerned that an enormous, ice-covered lake in Antarctica disappeared suddenly.
Researchers believe this disappeared act occurred during the 2019 Antarctica winter on the Amery Ice Shelf. It involved an estimated 21 billion to 26 trillion cubic feet (600,000,000 to 750,000,000 cubic meters) of water that was roughly twice as large as San Diego Bay.
Scientists who used satellite observation to record the astonishing disappearing act claim that the lake was drained in three days, after the ice shelf below it collapsed.
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"We believe that the weight of water that accumulated in this deep-lake opened a fissure on the ice shelf underneath the lake. This process is known as hydrofracture." Roland Warner, a University of Tasmania glaciologist and lead author of a new study detailing the event, stated in a statement. He said that the water flowed into the ocean below, much like Niagara Falls. It would have made for an amazing sight.
Hydrofracturing is a natural process that uses the same physical principles used in hydraulic fracturing or fracking to extract oil and gas from bedrock. It occurs when water, which is denser than ice, opens huge cracks in ice sheets, and then drains into seawater. The entire structure of the sheet is compromised by this giant fissure. Researchers are concerned that melting water streams and lakes will continue to grow on Antarctica's surface, which could lead to more hydrofracturing events. This could lead to ice shelves (including those anchored to ground) to collapse, raising sea levels beyond current projections.
The team published their study June 23 in Geophysical Research Letters. It stated that "Antarctic's surface melting has been projected by double by 2050, raising concern about the stability of all ice shelves." Hydrofracture and Flexure are still poorly understood, and the ice-sheet models don't yet reflect realistic treatment of these phenomena. (Flexure refers to the stretching of the underside ice-shelf due to the melting water above it. It is also a potential cause for the breakdown of ice-shelves.
Warner and his colleagues took aerial measurements to see the dramatic outpouring. They used observations from NASA's ICESat-2 satellite. This satellite takes readings by sending pulses of laser light off of a target and measuring how long it takes for them to reflect. Scientists can calculate the elevation of a target using this time delay.
The lake's surrounding area was freed from the water's weight after the deluge. It rose 118 feet (36m) from its original location. An enormous fracture known as an ice doline created an area of approximately 4.25 miles (11 km) along the lake bed. The lake was flooded with water within days. It reached a maximum flow rate of 35 million cubic feet (one million cubic meters) per hour during the summer 2020. Researchers aren't sure if this water will cause new fractures or already dissolve through an old fracture, and end up in the ocean.
Warner stated that the fracture could accumulate meltwater or flow to the ocean more often. It appears that the fracture was briefly reopened during the 2020 summer melt season. This is definitely something to keep an eye on. This event raises new questions about the frequency of deep-iced lakes on ice shelves, and how they evolve.
Original publication on Live Science