An international team of scientists from Scripps Institution of Oceanography, UC San Diego discovered the mysterious disappearance of a deep, large, ice-covered lake on the Antarctic ice shelf, baffling researchers.
The rare and mysterious event is said to have occurred during the 2019 Antarctic winter at the Amery Ice Shelf, East Antarctica, with an estimated 600-750 million cubic meters of water, roughly twice the volume of Sand Diego Bay, disappeared.
Unraveling the Mysteries of the Disappearing Antarctic Lake
Researchers utilized radar satellite imaging which allows them to see despite polar nights to pin the timing of the events through a week or less in June. A study published in the journal Advancing Earth and Space Science, entitled "Rapid formation of an ice doline on Amery Ice Shelf, East Antarctica," illustrates how once drained, there was a crater-like depression left in the Antarctic ice shelf surface, which covers roughly 11 square kilometers. The depression is known as an ice "doline" containing fractured remnants of the ice cover.
Roland Warner, lead author and glaciologist from the Australian Antarctic Program Partnership, explains that the team believes that the weight of water accumulation in the deep lake opened a fissure in the Antarctic ice shelf beneath the lake, a process named hydrofracture, which causes water to drain to the ocean below reports Phys.Org.
Hydrofracture and its Effects on the Mysterious Lake Disappearance
The process known as hydrofracture implicates the collapse of significantly smaller ice shelves in the Antarctic, where the meltwater forms on its surface during the austral summer. However, it is often not seen driving through the ice with a thickness of 1,400 meters on the Amery Ice Shelf.
The austral winter was captured by a green-light laser on NASA's ICESat-2, which transmits photon pulses to accurately locate reflection points of each photon received back from Earth.
Helen Amanda Fricker, co-author and glaciologists at Scripps Institution of Oceanography says that the team was excited at the details provided by ICESat-2, eliminating the processes occurring on the Antarctic ice sheet at a fine spatial scale. She adds that meltwater on ice shelf surfaces can cause collapses, ultimately leading to sea-level rise once grounded ice is no longer prevented; it is vital to understand the various processes that weaken the Antarctic ice shelves.
In recent years, with the rise of air temperatures, ice shelves have been experiencing greater surface melting. Most model projections for future warming show continuing trend creating numerous more melt lakes. This, therefore, increases the widespread risks of hydrofracturing that could lead to ice shelves completely collapsing, permitting a faster discharge of ice from grounded ice sheets and significantly increasing sea levels.
The mysterious lakes' uplift created a new lake of shallow arm front of the original one. Researchers perceive that by the next melt season, the lake will be filled in days at roughly more than a million cubic meters per day, overflowing into the cavity.
The team explains that the future of the new crater-like crevice in the lake is uncertain. It may accumulate meltwater and drain it again to the ocean frequently or reopen other fissures.
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