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The most advanced Earth observation laser ever launched by NASA has spotted two more subglacial lakes under the Antarctic ice.
The discovery could help scientists understand a “plumbing system” hidden under the frozen continent that may hold secrets about its future.
Seen from above, the Antarctic ice sheet looks like a calm, perpetual sheet of ice, but it hides hundreds of meltwater lakes where the ice sheet meets the bedrock of the continent, said the Nasa.
The space agency’s Ice, Cloud and land Elevation 2 satellite, or ICESat-2, has enabled scientists to accurately map subglacial lakes.
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The satellite measures the height of the surface of the ice which, despite its enormous thickness, rises or falls as the lakes fill or empty under the ice cap.
The hydrological systems under the Antarctic ice sheet have been a mystery for decades.
That started to change in 2007, when Helen Amanda Fricker, a glaciologist at the Scripps Institution of Oceanography at the University of California at San Diego, made a breakthrough that updated the classical understanding of subglacial lakes in Antarctic.
Using data from the original ICESat in 2007, Fricker first discovered that under the rapid ice currents of Antarctica, an entire network of lakes connect to each other, actively filling and draining over time.
Previously, these lakes were thought to hold meltwater statically, without filling or emptying.
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Matthew Siegfried, assistant professor of geophysics at the Colorado School of Mines in Golden, Colorado, and principal investigator of the new study, said: “The discovery of these interconnected systems of lakes at the interface of the ice bed that move the water, with all these impacts on glaciology, microbiology and oceanography – this was a great discovery of the ICESat mission.
“ICESat-2 is like putting on your goggles after using ICESat, the data is so precise that we can really start to draw the lake’s boundaries on the surface.”
To study regions where subglacial lakes fill and drain more frequently with satellite data, Siegfried worked with Fricker, who was instrumental in designing how the ICESat-2 mission observes polar ice. from space.
Siegfried and Fricker’s research shows that a group of lakes, including Lakes Conway and Mercer beneath the Mercer and Whillans Ice Streams in West Antarctica, are experiencing a period of drainage for the third time since the original ICESat mission began. to measure changes in altitude over area in 2003.
The two newly discovered lakes are also found in this region.
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In addition to providing vital data, the study found that the contours or boundaries of lakes can gradually change as water enters and leaves reservoirs.
“We’re really mapping all the height anomalies that exist at this point,” Siegfried said. “If there are lakes that are filling and emptying, we will detect them with ICESat-2.”
Accurate measurements of basal meltwater are crucial if scientists are to better understand Antarctica’s subglacial plumbing system and how all of this freshwater might alter the speed of the ice sheet above or the circulation of the ocean into which it ultimately flows.
Fricker said: “These are processes taking place under Antarctica that we would have no idea about if we didn’t have satellite data.
“We have struggled to get good predictions about the future of Antarctica, and instruments like ICESat-2 are helping us to observe at the scale of the process.”
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