For the first time, Columbia University scientists have mapped a massive groundwater system actively circulating in sediments deep in West Antarctica.
They say such systems, perhaps common in Antarctica, It may have hitherto unknown effects on how the frozen continent reacts to climate changeOr maybe even how he contributes to it. The research was published in the journal Science.
In recent years, researchers in Antarctica have discovered hundreds of liquid lakes and rivers interconnected within the ice itself. s It has captured thick basins of sediment under the ice, likely containing the largest reservoirs of water ever.
“People have assumed there may be deep groundwater in these sediments, but so far, no one has done any detailed imaging,” lead study author Chloe Gustafson, who conducted the research as a student at UCLA, said in a statement. At the Lamont-Doherty Observatory at Columbia University.
“The amount of groundwater we found was so great that it probably affects the processes of ice flows.. Now we need to learn more and figure out how to incorporate that into the models.”
through decades, Scientists have flown radar and other instruments over the Antarctic ice cap to image underground features. Among many other things, these expeditions revealed sedimentary basins sandwiched between ice and shale. But airborne geophysics can usually only reveal the approximate outlines of these features, not the water content or other features.
In one exception, a 2019 survey of the McMurdo Dry Valley in Antarctica used helicopter-mounted instruments to Documenting a few hundred meters of subglacial groundwater under about 350 meters of ice.
But most The known sedimentary basins of Antarctica are much deeper and most of their ice is much thicker, outside the range of airborne devices. In some places, researchers have drilled the top few meters of ice down into the sediment. Therefore, models of ice sheet behavior only include hydrological systems just inside or below the ice.
This is a huge deficiency. Most of the sprawling sedimentary basins in Antarctica lie below current sea level, sandwiched between ground ice intertwined with a bedrock layer and floating sea ice shelves adjacent to the continent.
They are believed to have formed on the sea floor during warm periods, when sea level was higher. If ice shelves recede in a warmer climateocean water can re-invade sediments and the glaciers behind them can advance and raise sea levels around the world.
In the new study, researchers focused on the 60-mile-wide Whillans Ice Stream. One of six fast-moving currents that feed the Ross Ice Shelf, the largest in the world, the size of the Canadian Yukon Territory.
Their analysis showed that, depending on the location, the sediment under the ice bed extends from half a kilometer to nearly two kilometers before it touches the bedrock. They confirmed that the sediments are filled with liquid water to the bottom. The researchers estimate that if it were completely removed, it would form a column of water 220 to 820 meters high, at least 10 times higher than the shallow hydrological systems within and at the ice base, and possibly much higher.
However, the researchers say, if the surface of the ice becomes thinner – a distinct possibility as the climate warms – the direction of water flow could reverse. The pressures above will decrease and Deep groundwater can begin to flow towards the base of the ice.
This can increase the lubrication of the ice base and increase its forward movement. Also, if deep groundwater flows, it can transfer geothermal heat naturally generated in bedrock; This may melt the ice base and push it forward. But it is not clear if and to what extent.
*With information from Europa Press
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