Scientists Discover Ancient River Landscape Hidden Beneath East Antarctic Ice Sheet
The landscape likely remained buried under ice for 34 million years.
According to a new study, global warming could uncover an ancient river landscape that has been preserved under the East Antarctic ice sheet for millions of years.
While the mass retreat of ice on the continent has not yet reached the ancient landscape, future conditions may change due to predicted climate warming, as stated in an article published in the journal Nature Communications on Tuesday.
Ice has been present in Antarctica for about 34 million years, but prior to this, the continent was relatively warm, with a climate similar to that of modern-day southern South America, such as the Patagonia region in Argentina and Chile, says Stuart Jamieson, author of the research and a researcher studying glacier behavior, long-term evolution, and landscape evolution at Durham University in the United Kingdom. There is evidence that at some point, Antarctica had tropical vegetation, including palm trees, Jamieson told ABC News.
Scientists recently discovered a large river landscape in Antarctica that existed at that time, located in the Aurora Subglacial Basin within the Denman and Totten glaciers. The river was supposed to flow from the middle of the continent to the coast between 34 and 60 million years ago, when other modern continents, such as Australia and India, separated from Antarctica and the supercontinent Gondwana, Jamieson said.
The landscape, estimated to have been under the ice shelf for 14 to 34 million years, was discovered using satellites and ice-penetrating radar.
According to Jamieson, researchers knew a lot about the topography under the ice sheet before they developed this technique, flying on radar-equipped planes to see the shape of the landscape beneath it. However, planes cannot fly everywhere, so there were large gaps between the places where planes flew and took measurements, he noted.
According to the study, the landscape consists of three raised blocks carved by rivers, separated by deep troughs located only 217 miles from the edge of the ice sheet. These blocks formed before glaciation, when rivers crossed the region and reached the coastline, which opened during the breakup of the Gondwana supercontinent.
When Antarctica began to cool slightly, small glaciers grew in the valleys of the rivers, according to Jamieson. But then a major cooling occurred, leading to the expansion of the East Antarctic ice sheet, which grew and covered the entire continent, burying the river landscape underneath it, Jamieson said.
"When this happens, it's like putting the landscape in a deep freeze, and it's almost like freezing it in time," Jamieson said.
According to the researchers, the breakup of the Gondwana supercontinent also led to the formation of valleys between the mountain blocks before the highlands were covered in ice.
Results show that the ice in this region has mainly remained stable for millions of years, despite intermittent warm periods. According to Jamieson, researchers hope to obtain samples of deposits and rock formations to learn more about the vegetation and ecosystem that existed during the river's activity.
However, according to the study, climate warming could lead to the retreat of ice in this region for the first time in at least the last 14 million years.
While Western Antarctica has experienced the greatest ice loss on the continent, especially the so-called "Doomsday Glacier," which could raise sea levels by 10 feet if it completely melts, the ice shelf located in East Antarctica contains the equivalent of 60 meters—or almost 200 feet—of sea-level rise, according to the study.
According to a study published earlier this month, it may already be too late to prevent significant melting in West Antarctica, even with the most ambitious efforts to mitigate the consequences.