Giant underground water system discovered under Antarctica ice

Many scientists say liquid water is the key to understanding the behavior of the frozen form found in glaciers. It is known that melt water softens its gravel bases and speeds up its march towards the sea. In recent years, researchers in Antarctica have discovered hundreds of interconnected liquid lakes and rivers located in the ice itself. They envisioned thick basins of sediment under the ice, potentially containing the largest reservoirs of water ever. But until now, no one has confirmed the presence of significant amounts of liquid water in the sediments under the ice, and no one has studied how it might interact with the ice.

In late 2018, a U.S. Air Force LC-130 Gustafson, along with geophysicist Lamont Doherty, Kerry Key, Colorado School of Mines geophysicist Matthew Siegfried, and mountaineer Megan Seifert, departed in Whillans. Its task is to better map the sediments and their properties using geophysical instruments placed directly on the surface. Far from any help if something went wrong, it would take six grueling weeks of traveling, digging in the snow, planting tools, and performing countless other tasks.

sediment in a lot of water

The team used a technology called magnetic imaging, which measures the penetration of natural electromagnetic energy generated in the planet’s atmosphere into the Earth. Glacial water, sediment, fresh, salty, and rocky water all conduct electromagnetic energy to varying degrees; By measuring the differences, researchers can create MRI-like maps of different items. The team planted their tools in snow pits for a day or two, then dug them up and moved them, eventually taking readings at about forty locations. They also reanalyzed natural seismic waves emanating from the Earth that were collected by another team to help characterize bedrock, sediments and ice.

Their analysis showed that, depending on the location, the sediment extends below the ice base from half a kilometer to nearly two kilometers before it reaches the bedrock. They confirmed that the sediment was filled with liquid water along the way. The researchers estimate that, if fully extracted, it would form a column of water 220 to 820 meters high – at least 10 times higher than the shallow hydrological systems at and at the base of the ice – and possibly much more. .

Salt water conducts energy better than fresh water, so they were also able to show that groundwater becomes saltier with depth. This makes sense, Key said, because he believes the sediments formed in a marine environment a long time ago. It is likely that ocean waters last reached the area now covered by Whillans during a warm period about 5,000 to 7,000 years ago, saturating the sediments with salt water. When the ice moved forward again, it was evident that the melt water created by pressure from the top and friction at the base of the ice had been visibly pushed into the upper sediments. Key said he may continue to filter and mingle today.

The researchers say this slow draining of fresh water into the sediment can prevent water from accumulating at the base of the ice. This can act as a curb on the forward movement of the ice. Measurements taken by other scientists at the land line of the ice stream – the point where the ground ice stream meets the floating ice shelf – show that the water there is slightly less saline than normal seawater. This indicates that fresh water flows through the sediment into the ocean, making way for more meltwater to enter and keeping the system stable.

research questions

However, the researchers say, if the surface of the ice is thin – a distinct possibility as the climate warms – the direction of the water flow can be reversed. Suspended pressures will decrease and deep groundwater can begin to flow toward the ice base. This can increase the lubrication of the ice base and increase its forward movement. (Whillans are already moving the ice toward the sea at a rate of about a meter per day—too fast for glacial ice.) Also, if deep groundwater is flowing upward, it can transfer naturally generated geothermal heat in the bedrock; This may melt the ice base and push it forward. But it is not clear if and to what extent this will happen.

“Ultimately, we don’t have significant limitations on sediment permeability or the speed with which the water flows,” Gustafson said. “Will it make a huge difference in generating an out-of-control reaction? Or does groundwater play a minor role in the grand scheme of ice flow?”

The known presence of microbes in the shallow sediments adds another suspicion, the researchers say. It is probable that this basin and others were inhabited below; And if groundwater begins to rise, it will bring in dissolved carbon that these organisms use. The lateral flow of groundwater will then send some of this carbon to the ocean. This would turn Antarctica into a hitherto unthinkable carbon source for a world it’s already swimming in. The question is whether that will have any significant impact, Gustavon said again.

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