A new study reveals that the groundwater system, found in sediments deep in West Antarctica likely to be in the form of a wet sponge, is revealing an unexplored part of the region and may have implications for how the frozen continent reacts to the climate crisis.
“People have assumed there may be deep groundwater in these sediments, but so far, no one has done any detailed imaging,” said lead author of the study, Chloe Gustafson, a postdoctoral researcher at UCSD’s Scripps Institute. Oceanography, in a news release.
“Antarctica has 57 meters (187 feet) of sea-level rise potential, so we want to make sure that we integrate all the processes that control how ice flows from the continent into the oceans. Groundwater is currently a process that is missing in our models of ice flow” , added via email.
The ice sheet covering Antarctica is not all solid. In recent years, researchers in Antarctica have discovered hundreds of interconnected liquid lakes and rivers contained within the ice itself. But this is the first time that large amounts of liquid water have been found in sediments under the ice.
The authors of this study, which was published in Science on Thursday, 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 the Canadian territory of Yukon.
Gustafson and her colleagues spent six weeks in 2018 mapping the sediments under 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, sediment, rocky freshwater, and saltwater and create a map from these different information sources.
“We filmed from the ice sheet to a distance of approximately five kilometers (3.1 miles) Co-author Kerry Key, associate professor of Earth and Environmental Sciences at Columbia University, said in a separate statement.
The researchers calculated that if they could squeeze groundwater from the sediment in the 100 square kilometers (38.6 square miles) they drew at 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 approximately 420 meters (1378 feet) tall,” Gustafson, who conducted the research as a graduate student at Columbia University’s Lamont-Doherty Earth Observatory, said in the statement.
“At the shallow end, our water will rise to the middle of the Empire State Building about halfway. At the deepest end, there are approximately two Empire State Buildings stacked on top of each other. This is significant because subglacial lakes in this area range from 2 to 15 meters ( 6.6 to 49 feet.) This is like one to four stories of the Empire State Building.”
How did you get there?
The maps revealed that the water became more saline with depth, as a result of the formation of the groundwater system.
Ocean waters likely reached the area during a warm period 5,000 to 7,000 years ago, saturating the sediments with salty seawater. As the ice progressed, the fresh meltwater generated by pressure from the top and friction at the ice base was pushed into the upper sediments. It may continue to percolate 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 in relation to the climate crisis and rising sea levels.
The slow draining of water from the ice into the sediment would have prevented water from accumulating at the base of the ice – preventing the ice from moving forward toward the sea.
However, if the surface ice sheet is thin, the pressure drop may allow these deeper waters to rise. This upward movement will soften the base of the ice and speed up its flow.
Winnie Chu, assistant professor at Georgia Institute of Technology, wrote in a commentary on the research, which was published in the journal Science. She did not participate in the study.
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