Have you ever wondered what lies beneath those colossal ice sheets in Antarctica ? Scientists too, and now a new study published in the journal Science reveals what they have found under the depths of the Antarctic ice.
unexpected find
A team of researchers from Columbia University (USA) has discovered, for the first time, thanks to electromagnetic techniques, a huge system of actively circulating groundwater in sediments deep in West Antarctica.
“Scientists had hypothesized that there might be deep groundwater in these sediments, but until now no one has gotten detailed images,” said Chloe Gustafson, study leader and student at Columbia University’s Lamont-Doherty Earth Observatory. . “The amount of groundwater we found was so significant that it probably influences ice flow processes. Now we need to find out more and figure out how to incorporate that into the models.”
According to experts, water is key to understanding the behavior of the frozen form of glaciers. Meltwater is known to lubricate the base of a glacier and accelerate movement out to sea. In addition, this groundwater may exist in similar conditions on other planets or moons that release heat from their interiors.
“You can imagine a frozen cap on top of a liquid interior, whether it’s completely liquid or liquid-saturated sediments,” says Kerry Key, associate professor of earth and environmental sciences at Columbia University. “What we see in Antarctica can be thought of as potentially analogous to what we might find on Europa or on other ice-covered planets or moons.”
More implications
The existence of this unexpected reservoir of actively circulating groundwater in sediments deep in West Antarctica also has implications for the release of large amounts of carbon that were previously stored by seawater-adapted communities of microbes. “Groundwater movement means there is potential for more carbon to be transported to the ocean than we had previously considered,” says Gustafson.
Most of Antarctica’s sedimentary basins lie below present-day sea level and are thought to have formed on the seafloor during warm periods when sea levels were higher. In a warmer climate scenario, these ice shelves could recede, allowing ocean waters to re-invade the sediments, and the glaciers behind them could raise sea levels around the world.
The researchers focused on the Whillans Ice Stream, one of the fast-moving streams that feed the Ross Ice Shelf, the world’s largest, and used a technique called magnetotelluric imaging to map the sediments beneath the ice over a six-year period. weeks. Depending on location, sediments extend below the ice base from half a kilometer to almost two kilometers before touching bedrock. It was found that the sediments are loaded with liquid water to the bottom. They calculated that if they were able to extract the groundwater from the sediments in the 100 square kilometers they mapped on the surface , it would form a lake that ranged from 220 to 820 meters deep.
In the last decade, airborne electromagnetic techniques have been used to image shallow groundwater in the upper 100 to 200 meters below some thin glaciers and permanently frozen areas of the McMurdo Dry Valleys: but those techniques can only see through about 350 meters of ice. The Whillans ice stream is about 800 meters thick.
The new study is just a start in addressing a myriad of questions, the researchers say. “Confirmation of the existence of deep groundwater dynamics has transformed our understanding of ice stream behavior and will force modification of subglacial water models.”
Referencia: “A dynamic saline groundwater system mapped beneath an Antarctic ice stream” by Chloe D. Gustafson, Kerry Key, Matthew R. Siegfried, J. Paul Winberry, Helen A. Fricker, Ryan A. Venturelli and Alexander B. Michaud, 5 May 2022, Science.
DOI: 10.1126/science.abm3301
