A huge Antarctic Lake disappeared over the course of just three days in June 2019 after the ice shelf beneath the lake collapsed, reports Ben Turner for Live Science. The fractured ice shelf sent an estimated 21 to 26 billion cubic feet of water into the ocean.
Researchers spotted the vanishing lake while poring over satellite imagery of the region and published their analysis of the event last week in the journal Geophysical Research Letters.
Roland Warner, a glaciologist at the University of Tasmania and lead author of the study, tells Becky Ferreira of Vice that in January 2020 he was monitoring the destruction wrought by last year’s catastrophic wildfires in Australia using satellite imagery when he decided to take a peek farther south.
“Looking down to Antarctica, for a break from watching the destruction, I noticed a spell of several clear days on Amery Ice Shelf and decided to see how the summer surface melt season was progressing,” he tells Vice via email. “The collapsed surface feature caught my eye.”
By looking back in time at prior satellite imagery from NASA’s ICESat-2, Warner was able to pinpoint the lake’s demise. On June 9, 2019, the lake was there, but by June 11 it was gone, according to Vice.
"We believe the weight of water accumulated in this deep lake opened a fissure in the ice shelf beneath the lake, a process known as hydrofracture, causing the water to drain away to the ocean below," Warner says in a statement. A hydrofracture is what happens when the accumulated weight of liquid water, which is denser than ice, gets too great and the ice sheet supporting it cracks.
In another statement, Warner described the sudden release of water, saying “the flow into the ocean beneath would have been like the flow over Niagara Falls, so it would have been an impressive sight."
The collapse that drained this lake like a bathtub also caused the surrounding area to rise some 118 feet because the weight of the water had suddenly been lifted, according to Live Science.
As climate change continues to drive more surface melting across Antarctica, researchers are concerned hydrofracturing could become a more widespread phenomenon with uncertain implications for sea level rise, according to Live Science.
In the study, the researchers write:
Antarctic surface melting has been projected to double by 2050, raising concerns about the stability of other ice shelves. Processes such as hydrofracture and flexure remain understudied, and ice-sheet models do not yet include realistic treatment of these processes.
Surprisingly, this icy lake is now filling up again. Per Live Science, in the summer of 2020, the lake refilled in a few days, peaking with 35 million cubic feet of water flowing into the lake in a single day.
Warner and his co-authors also hope to explore questions related to what led to the formation of such a massive lake on the surface of the Amery Ice Sheet in the first place.
“How did the lake evolve to develop its thick insulating ice lid and eventually store such a large volume of water?” Warner tells Vice. “We can look back at the surface history of the system in several decades of satellite images.”