Lake Whillans is a strange mass of water, starting with the fact that there is liquid to fill it. Despite being buried more than 2,000 feet under the Antarctic ice sheet, its temperature climbs only to zero degrees Celsius, thanks to a combination of geothermal warmth, strong friction from shaved ice, and that thick ice cover that preserves the atmosphere. protect it from the polar air. With so much pressure down there, that’s just cool enough to keep the water in the lake. Oddly enough, Lake Whillans is also full of life. A survey a decade ago found thousands of types of microscopic organisms, thought to be feeding on nutrients from seawater that flooded the basin several millennia ago, when glaciers last receded.
More recently, Chloe Gustafson, a geophysicist at the Scripps Institution of Oceanography, traveled to the distant ice sheet above Lake Whillans with another mystery in mind: What’s going on beneath that lake? Antarctic researchers have long suspected that water pipes beneath the glacier go much deeper than they could see. Any groundwater below the lake would have implications for how the ice above moves into the ocean and so it could contribute to tide. But they could not prove with certainty what the groundwater was there. It’s too deep, too ice-covered to be mapped with traditional glacial tools, like bouncing radar signals off the ice or creating explosives and listen to the shock waves.
In a published study in the magazine Science, Gustafson’s team produced a long-awaited diagram of the watery world beneath the ice. A vast underground reservoir more than a kilometer long beneath subglacial water features such as Lake Whillans, holds 10 times as much water. To see that, the researchers turned to a technique called magnetometry, or MT, which exploits natural variations in the Earth’s electromagnetic field to paint a big picture of the sediment. under. They expect similar groundwater systems to underlie other areas where ice is rapidly flowing — so-called ice streams that account for about 90 percent of the ice that goes from the mainland to the ocean. “This is part of the puzzle of why this ice is flowing the way it is,” Gustafson said. “So it’s really important to understand what’s going to happen to Antarctica.”
Scientists have long understood that the water under the ice plays an important role in the movement of the ice above it. One factor is how it alters the underlying sediment, creating grooves and planes in the terrain. Another way is to lubricate the ground, which helps the ice slide faster. “If you have water on the Slip ‘n Slide, you’ll slide pretty quickly,” says Gustafson. “If you don’t have water, you won’t get far.” Understanding subglacial hydrology is especially important for researchers racing to model particularly precarious ice regions, such as the Thwaites Glacier, a few hundred miles from Whillans. In January, a group The researchers reported that Thwaites — the so-called Doomsday Glacier, which contains enough ice to raise global sea levels by 2 feet — could collapse within five years.
But without groundwater, those models are incomplete. Slawek Tulaczyk, a professor of earth sciences at UC Santa Cruz who studied the area but was not involved in the study, said researchers have long observed more water seeping out from beneath the Whillans ice sheet than anticipated. ants. This is so strange. As the ice sheets approach the ocean, they tend to be thinner and therefore less good at insulating the ground from the icy Antarctic air. At these edges, the water tends to freeze, slowing the movement of the ice. But that’s not what glaciologists are seeing. “This is a difficult problem,” he said. Somehow the patterns they observed were “thermodynamics of hindrance”. The researchers hypothesize that nearly half of that water must have risen from untapped sources underground.
Gustafson’s team mapped it. The ice sheet above Lake Whillans lies west of Antarctica, at the foot of the trans-Antarctic peaks that divide the continent. The area was favored by scientists conducting research in the pre-GPS era because those mountains helped aid in navigation. But it’s remote. “It was the longest, most grueling camping trip of my life,” says Gustafson of his weeks trudging across the ice, digging holes where the group would leave passive listening devices for electromagnetic signals. The tools will sit there for 24 hours before the researchers dig them up and move them to the next site two kilometers away.
