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Antarctic lake suddenly disappeared

Side view of frozen Antarctic lakes  The right part drains the water.
A before-and-after comparison of the ice-covered lake on Antarctica’s Amery Ice Shelf. Shown blue around the edge of the ice, with the lake looking out to the left. To the right, the water has drained. and the ice above was crumpled and bent in response. Pictured here was taken by Landsat 8 during a summer day in 201
9. Photo by Landsat 8/ UC San Diego.

Now you see it, now you don’t don

Scientists saw the icy lake on the Amery Ice Shelf in Antarctica in April 2019, but in June of that year the lake has drained only doline left which is a sinkhole like a crater that is covered with debris the lake used to be Scientists believe that the weight of the accumulated ice created a large rift beneath the lake. which was vented in June in what they said was “rare event”

The team of scientists published their study in the journal peer-reviewed Geophysical Research Letters On June 23, 2021, lead author Roland Warner from the Australian Antarctic Program Partnership at the University of Tasmania said:

We believe that the weight of the water accumulated in this deep lake has opened a fissure in the ice shelf below the lake. which is a process known as hydrofracturing causing the water to flow out into the ocean below

Hydrofracture It is the fracture of rocks caused by water. Often while freezing Scientists have seen the birth hydrofracturing On an ice shelf in Antarctica But they’ve never seen it on such a large ice shelf. The Amery Ice Shelf, where the lake once stood, is 4,590 feet (1,400 meters) thick.

How to watch in the darkness of the polar winter

The Amery Ice Shelf is located at 69 degrees south. June is winter in the Southern Hemisphere. which is almost always dark at this ice shelf Scientists used the green laser instrument aboard NASA’s ICESat-2 to see what was happening on the ground below. It basically gives scientists a vision in the dark. The laser sends light waves to the surface. reflected back And scientists were able to record the travel time of light.

In this way, they could see the disruption on the ice shelf. The surface of the ice fell 260 feet (80 m) as the lake drained. Massive water loss on the ice shelf makes the mezzanine lighter. Thus, the surroundings of the lake rebounded 118 feet (36 m).

The black cube on the graph shows the southern winter dark hours.
At the location of the Amery Ice Shelf, 69 degrees south of the Earth, darkness reigned in June. with only a dim twilight shining through the day. Image via Antarctica.gov.

The University of Minnesota’s Polar Geospatial Center has produced maps that show the disruption is also changing the landscape around the newly created doline, with an area of ​​23 square miles (60 square kilometers).

Helen Amanda Fricker of the Scripps Institution of Oceanography at UC San Diego said:

It is exciting to see ICESat-2 in detail the processes occurring on the ice sheet at such a fine scale. This is because the water that melts on the surface on the ice shelf can cause it to collapse. This will ultimately cause sea levels to rise when crushed ice is no longer trapped. It is important to understand the process by which the ice shelf is weakened.

Billions of cubic feet of water lost at sea

Scientists measured the doline that displaces the lake at 4.25 square miles (11 square kilometers). They estimate that 21 to 26 billion cubic feet (600 to 750 million cubic meters) of water flows into the ocean twice the volume of the bay. San Diego

Jonathan Kingslake of Columbia University said:

This sudden event is evidently the culmination of decades of melt water accumulation and storage under an insulating ice cap.

Manhattan computer graphics with large blue blocks towering over one section.
To visualize the amount of water lost on the Amery ice shelf, this computer graphic shows 21 to 26 billion cubic feet of water atop Manhattan. Image by Philipp Arndt/Scripps Institution of Oceanography at UC San Diego.

The uplift from the disruption created a new shallow lake that was replenished during the next melting season over the course of a few days. It overflowed into the old doline cavity when ICESat-2 crossed the doline again a few days later and took further measurements. A melt channel was found to cut into the doline that was 65 feet (20 m) wide and 10 feet (3 m) deep.

a glimpse of a warm future

In the future, as warmer temperatures in Antarctica cause more surface ice to melt. Hydrolysis will continue to break the ice shelf and allow more water to flow into the ocean. and increase sea level rise Now researchers have seen that thick layers of ice can also experience the birth of hydrofracturing which must be considered in forecasts for future global warming.

The snow-white landscape is dotted with dark teal and crumpled.
The Landsat 8 satellite captured an image of melt water on the Antarctic Amery ice shelf during the summer. Image via UC San Diego.

Investigators are uncertain about Doleine’s future. and whether it accumulates more dissolved water and drains it more often? In the meantime, they will keep an eye on it.

Bottom line: For years, meltwater accumulated in Antarctica’s Amery Ice Shelf lakes suddenly drained into the ocean during the winter of 2019.

Source: Rapid ice formation on the Amery Ice Shelf, East Antarctica.

Through the UC San Diego Institute of Oceanography Scrippsps

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