The landscape has likely been buried under ice for up to 34 million years.
Global warming could reveal an ancient river landscape that has been preserved under the East Antarctic ice sheet for millions of years, according to a new study.
While the continent’s massive glacial retreat has yet to touch the ancient landscape, that may change in the future with expected climate warming, according to the research paper published Tuesday in Nature Communications.
Ice has been present in Antarctica for about 34 million years, but before that the continent was relatively warm, with a climate similar to that of modern-day southern South America, such as the Patagonia region of Argentina and Chile, says Stuart Jamieson, author of the research. There is evidence that at one time, there were tropical plants, including palm trees, in Antarctica, Jamieson told ABC News.
Scientists have recently discovered a large river-carved landscape in Antarctica that existed during that period, located in the Aurora-Schmidt basins within the Denman and Totten glaciers. The river likely dried up from the mid-continent toward the coast between 34 million and 60 million years ago, around the time other modern continents like Australia and India were breaking away from Antarctica and the supercontinent Gondwana, Jamieson says. He said.
The landscape, which is estimated to have been buried under the ice shelf for between 14 million and 34 million years, was found using satellites and ice-penetrating radar.
Before developing this technology, researchers knew a lot about the terrain under the ice sheet by flying planes equipped with radar to see what the landscape looked like underneath, Jamison said. He noted that planes can’t fly everywhere, so there were large gaps between where the planes flew and where the measurements were taken.
The landscape consists of three elevated blocks carved into a river shape, separated by deep basins, and is only about 217 miles from the edge of the ice sheet, according to the study. These blocks formed before the Ice Age, when rivers crossed the area to the coastline that opened up during the breakup of the Gondwana supercontinent.
As Antarctica began to cool a bit, small glaciers grew in the river valleys, Jamieson said. But then significant cooling occurred, triggering an expansion of the East Antarctica ice sheet, which grew to cover the entire continent, burying the riverine landscape underneath, Jamieson said.
“When that happens, it’s basically like turning on a refrigerator for our little landscape, kind of freezing it in time,” Jamieson said.
The breakup of the supercontinent Gondwana also caused valleys to form between the highlands, before the highlands became glacial, the researchers said.
The results suggest that the ice over the region has remained largely stable over millions of years, despite warm periods in between. In the future, researchers hope to obtain sediment and rock samples to learn more about the vegetation and ecosystem that existed when the river was active, Jamison said.
However, a warming climate could cause ice to retreat in this region for the first time in at least 14 million years, according to the study.
While West Antarctica has seen the largest rate of melting on the continent — particularly the so-called “Doomsday Glacier” that could raise sea levels by 10 feet if it melted completely — the ice shelf in East Antarctica contains the equivalent of 60 meters — or nearly 200 feet — of sea level rise, according to the study.
It may be too late to prevent significant ice melting in West Antarctica, even with the most ambitious mitigation efforts, according to a study released earlier this month.
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