Found in sediments deep in West Antarctica and likely in the form of a wet sponge, the groundwater system reveals an unknown part of the region, a new study reveals and may have implications for how the frozen continent responds to the climate crisis .
“People have assumed that there is deep groundwater in these sediments, but so far no one has done detailed imaging,” said lead author Chloe Gustafson, a postdoctoral researcher at UCSD’s Scripps Institute. Oceanography, in a press release.
“Antarctica has a sea level rise potential of 57 meters (187 feet), so we want to make sure we integrate all the processes that determine how ice flows from the continent to the oceans. Groundwater is currently a missing process in our ice flow models,” he added. via email.
The ice sheet covering Antarctica is not completely solid. In recent years, researchers in Antarctica have discovered hundreds of interconnected liquid lakes and rivers that reside within the ice itself. But this is the first time large amounts of liquid water have been found in sediments beneath the ice.
The authors of this study, published Thursday in Science, focused on a width of 60 miles (96.6 kilometers wide). Whillans Ice Stream, one of six streams feeding the Ross Ice Shelf, the largest in the world, the size of Canada’s Yukon Territory.
Gustafson and his colleagues spent six weeks in 2018 mapping the sediments beneath the ice. The research team used geophysical instruments placed directly on the surface to implement a technique called magnetic imaging.
This technology can detect the different degrees of electromagnetic energy generated by ice, sediments, rocky freshwater and saltwater and create a map of these different sources of information.
“We fired from the ice sheet at a distance of about three miles (3.1 miles) Co-author Kerry Key, an associate professor of earth and environmental sciences at Columbia University, said in a separate statement.
The researchers calculated that if they could squeeze the groundwater out of the sediment in the 100 square kilometers (38.6 square miles) they pulled to the surface, it would be a lake 220 to 820 meters (722 to 2,690 feet) deep. .
“The Empire State Building to the antenna is about 420 meters (1,378 feet) high,” Gustafson, who conducted the research as a graduate student at Columbia University’s Lamont-Doherty Earth Observatory, said in the statement.
“In the shallow end, our water will reach about halfway up the Empire State Building. At the deepest end, there are about two Empire State Buildings stacked on top of each other. This is important because subglacial lakes in this area range from 2 to 15 meters (6.6-49 ft). This is about one to four floors from the Empire State Building.”
How did you get there?
The maps showed that the formation of the groundwater system made the water saltier as the depth increased.
Ocean waters likely reached the area during a warm period from 5,000 to 7,000 years ago, which saturated the sediments with salty seawater. As the ice progressed, fresh meltwater generated by pressure from above and friction at the base of the ice pushed into the upper sediments. It can continue to seep and mix with groundwater today, Key said.
The researchers said there is more work to be done to understand the implications of the groundwater discovery, particularly with regard to the climate crisis and rising sea levels.
The slow drainage of water from the ice into the sediment would have prevented water from accumulating at the base of the ice, preventing the ice from advancing toward the sea.
However, if the surface ice sheet is thin, the pressure drop can cause these deeper waters to rise. This upward movement will soften the base of the ice and speed up its flow.
Winnie Chu, an assistant professor at the Georgia Institute of Technology, wrote a commentary on the research, which was published in the journal Science. She did not participate in the study.
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