US scientists have discovered large reservoirs of salt water under the glaciers of West Antarctica. The discovery will help to understand the mechanisms that are moving glaciers rapidly towards the sea, raising the level of the oceans.
Antarctic ice is constantly moving and drains into the sea by ice currents that form in the interior of the continent. It’s a natural process, which scientists monitor with GPS and satellite imagery.
The problem is that these currents are much faster than expected. This could mean that we are facing a total collapse of the glaciers of West Antarctica, says Heitor Evangelista, a specialist in climate change at Uerj (University of the State of Rio de Janeiro).
Glaciers on the edges of the continent act as a dam for the ice mass contained in the interior, holding and stabilizing it, mainly the Pine Island, Getz and Thwaites glaciers in West Antarctica. They already show cracking and advanced melting.
The collapse of glaciers in that region would raise sea levels by 1.3 meters. It would be an extraordinary change. For comparison purposes, from the beginning of the Industrial Revolution until today, there has been a rise of 18 cm in sea level.
“It is a very unstable scenario and conducive to a cataclysmic phenomenon, which could completely change the global sea level. And this could happen slowly or catastrophically”, says Evangelista.
The possible collapse of these glaciers is the main topic debated among Antarctic scholars today, adds the expert.
The discovered reservoirs are in an unstable region of Antarctica, below the Whillans Ice Stream, which already moves ice by about a meter a day — very fast for glacial ice.
“It is something very worrying, hence the discovery of these groundwater reservoirs has been published in the journal Science”, says the researcher.
Reservoirs may be one of the factors that explain the greater speed of ice currents, as they have been found to feed subglacial rivers and lakes, which lubricate the bases of glaciers and accelerate their slide towards the sea, raising the level of the oceans.
Previous research has shown that flooding subglacial lakes in East Antarctica increases the speed of ice flow.
Instability in the western part of Antarctica has been extensively studied for decades. Large portions of its bed are below sea level and sloping inland. The retreat of the ice edges in this region would allow the invasion of seawater, causing rapid destabilization and disintegration of the entire glacier.
Scientists have recorded record temperatures in Antarctica, shrinkage and cracks in continental and floating ice (flyes) due to global warming caused by human action. Recently, a heat wave with temperatures of up to 40°C in the eastern part of Antarctica caused the detachment of an ice cap with a surface equivalent to that of the city of Los Angeles.
The newly discovered reservoirs are contained in kilometer-deep sedimentary basins that lie beneath subglacial rivers and lakes and are separated from them by a thin layer of tilite, a sedimentary rock common in glaciers. Above the lakes and rivers is the thick layer of Antarctic ice with an average thickness of 2.5 km.
The reservoirs are made up of “fossil” marine waters, housed there more than 5,000 years ago, when the sea flooded the region in a warm period on Earth, when the glaciers were partially thawed. It is speculated that there is a connection between the reservoirs and the current sea.
“The next step is to incorporate deep groundwater into the study models,” said lead study author Chloe Gustafson, from Columbia University (USA), in an interview with Sheet.
Subglacial rivers and lakes were already known to science. It was once believed that the ice rested directly on the rocky soil of the continent. Today, it is known that these aquifers are spread across Antarctica, such as the giant and deep Lake Vostok, discovered by a Russian team in 1996 and which has live microorganisms in its interior.
For the researchers, there is also life in the reservoirs. “Our observations suggest that sedimentary basins are likely inhabited by microbial communities adapted to seawater,” they wrote in the paper.
Gustafson told Sheet that “it would be amazing if we could directly access the reservoirs, but with current subglacial drilling equipment it would be very difficult. It’s an engineering challenge.”
The discovery was made after a 2018 expedition to Antarctica made up of Gustafson, Kerry Key, Matthew Siegfried and mountaineer Meghan Seifert. They faced severe weather conditions, with freezing winds of 80 km/h, as you can see in the video (below) produced by the team.
They used an innovative method for discovery, magneto-telluric imaging. Equipment installed on the surface of the ice sends an electromagnetic signal towards the ground, and then the characteristics of the returning signals are analyzed. It works with a radar. As each substance reacts differently to the signal sent, it is possible to infer the characteristics of the materials found along the way.
The research was funded by the National Science Foundation (USA) and cost approximately US$ 500,000.
